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  • 102001. Yang, Weiqiang
    et al.
    Pan, Supriya
    Di Valentino, Eleonora
    Nunes, Rafael C.
    Vagnozzi, Sunny
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Mota, David F.
    Tale of stable interacting dark energy, observational signatures, and the H-0 tension2018In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 9, article id 019Article in journal (Refereed)
    Abstract [en]

    We investigate the observational consequences of a novel class of stable interacting dark energy (IDE) models, featuring interactions between dark matter (DM) and dark energy (DE). In the first part of our work, we start by considering two IDE models which are known to present early-time linear perturbation instabilities. Applying a transformation depending on the dark energy equation of state (EoS) to the DM-DE coupling, we then obtain two novel stable IDE models. Subsequently, we derive robust and accurate constraints on the parameters of these models, assuming a constant EoS w(x) for the DE fluid, in light of some of the most recent publicly available cosmological data. These include Cosmic Microwave Background (CMB) temperature and polarization anisotropy measurements from the Planck satellite, a selection of Baryon Acoustic Oscillation measurements, Supernovae Type-Ia luminosity distance measurements from the JLA sample, and measurements of the Hubble parameter up to redshift 2 from cosmic chronometers. Our analysis displays a mild preference for the DE fluid residing in the phantom region (w(x) < -1), with significance up to 95% confidence level, while we obtain new upper limits on the coupling parameter between the dark components. The preference for a phantom DE suggests a coupling function Q < 0, thus a scenario where energy flows from the DE to the DM. We also examine the possibility of addressing the H-0 and sigma(8) tensions, finding that only the former can be partially alleviated. Finally, we perform a Bayesian model comparison analysis to quantify the possible preference for the two IDE models against the standard concordance ACDM model, finding that the latter is always preferred with the strength of the evidence ranging from positive to very strong.

  • 102002. Yang, Weiqiang
    et al.
    Vagnozzi, Sunny
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Nordic Institute for Theoretical Physics (Nordita). University of Cambridge, United Kingdom.
    Di Valentino, Eleonora
    Nunes, Rafael C.
    Pang, Supriya
    Mota, David F.
    Listening to the sound of dark sector interactions with gravitational wave standard sirens2019In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 7, article id 037Article in journal (Refereed)
    Abstract [en]

    We consider two stable Interacting Dark Matter-Dark Energy models and confront them against current Cosmic Microwave Background data from the Planck satellite. We then generate luminosity distance measurements from O(10(3)) mock Gravitational Wave events matching the expected sensitivity of the proposed Einstein Telescope. We use these to forecast how the addition of Gravitational Wave standard sirens data can improve current limits on the Dark Matter-Dark Energy coupling strength (xi). We find that the addition of Gravitational Waves data can reduce the current uncertainty by a factor of 5. Moreover, if the underlying cosmological model truly features Dark Matter-Dark Energy interactions with a value of xi within the currently allowed 1 sigma upper limit, the addition of Gravitational Wave data would help disentangle such an interaction from the standard case of no interaction at a significance of more than 3 sigma.

  • 102003. Yang, X.
    et al.
    Li, Duan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ren, Z. H.
    Zeng, R. G.
    Gong, S. Y.
    Zhou, D. K.
    Tian, H.
    Li, J. X.
    Xu, G.
    Shen, Zhijian James
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Han, G. R.
    Colossal dielectric performance of pure barium titanate ceramics consolidated by spark plasma sintering2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 79, p. 75422-75429Article in journal (Refereed)
    Abstract [en]

    A facile sol-gel-hydrothermal method was developed to prepare well-dispersed BaTiO3 (BT) nanocrystals with a size of about 20 nm. By using such nanopowder, dense BT nanoceramics were densified via spark plasma sintering (SPS). Dielectric measurements reveal that pure BT nanoceramics have an extremely high permittivity up to 6 x 10(4) and a low dielectric loss. On the basis of microstructure characterization and dielectric measurement, it was proposed that the polaron dipoles configured by oxygen vacancies and Ti3+ cations within the grains could contribute to the colossal dielectric permittivity of the ceramics. By using the thermally activated polaron hopping model, a large activation energy EA has been determined (0.135 eV) below the Curie temperature, possibly due to the coupling of polaron dipoles and intrinsic ferroelectric dipoles. This simple method offers the possibility to produce pure BT nanoceramics with a colossal permittivity.

  • 102004. Yang, Xi-Xi
    et al.
    Mao, Qiu-Yun
    An, Xiao-Ting
    Li, Xi-Chen
    Siegbahn, Per E. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chen, Guang-Ju
    Tan, Hong-Wei
    Theoretical study of the mechanism of the manganese catalase KatB2019In: Journal of Biological Inorganic Chemistry, ISSN 0949-8257, E-ISSN 1432-1327, Vol. 24, no 1, p. 103-115Article in journal (Refereed)
    Abstract [en]

    The mechanism of the H2O2 disproportionation catalyzed by the manganese catalase (MnCat) KatB was studied using the hybrid density functional theory B3LYP and the quantum chemical cluster approach. Compared to the previous mechanistic study at the molecular level for the Thermus thermophilus MnCat (TTC), more modern methodology was used and larger models of increasing sizes were employed with the help of the high-resolution X-ray structure. In the reaction pathway suggested for KatB using the Large chemical model, the O-O homolysis of the first substrate H2O2 occurs through a -(1):(1) coordination mode and requires a barrier of 10.9kcal/mol. In the intermediate state of the bond cleavage, two hydroxides form as terminal ligands of the dimanganese cluster at the Mn-2(III,III) oxidation state. One of the two Mn(III)-OH- moieties and a second-sphere tyrosine stabilize the second substrate H2O2 in the second-sphere of the active site via hydrogen bonding interactions. The H2O2, unbound to the metals, is first oxidized into HO2<bold> through a proton</bold>-coupled electron transfer (PCET) step with a barrier of 9.5kcal/mol. After the system switches to the triplet surface, the uncoordinated HO2<bold> replaces the product water terminally bound to the Mn</bold>(II) and is then oxidized into O-2 spontaneously. Transition states with structural similarities to those obtained for TTC, where -(2)-OH-/O2- groups play important roles, were found to be higher in energy.

  • 102005. Yang, Y
    et al.
    författare, sjutton
    Östlin, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    IMAGES. I. Strong evolution of galaxy kinematics since z = 12008In: Astronomy and Astrophysics, Vol. 477, p. 789-Article in journal (Refereed)
  • 102006. Yang, Y.
    et al.
    Liu, Y. J.
    Chen, J.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wang, H. L.
    Zhang, Z. Q.
    Lu, Y. J.
    Wu, S. Q.
    Lin, J. X.
    Crystallographic features of alpha variants and beta phase for Ti-6Al-4V alloy fabricated by selective laser melting2017In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 707, p. 548-558Article in journal (Refereed)
    Abstract [en]

    The present study investigated the crystallographic features of a variants and beta phase for Ti-6Al-4V alloy fabricated by selective laser melting. The <100>(beta) fiber texture parallel to the building direction was ascertained on the basis of a reconstruction method realized by the manipulation of stereographic projection. The SLMed alloy has no alpha/alpha' variants selection but contains a special crystallographic area exhibiting random orientation which cannot be reconstructed as a parental columnar beta grain with the present introduced method due to its nature as the overlapped area between adjacent melt pools resulting from the heterogeneous nucleation in front of the liquid-solid interface. With increasing the heat treated temperature, alpha variants selection occurs. Especially at higher temperature of 905 degrees C, the intergranular beta phase following a reversed crystallographic path as parental beta phase->alpha variants->intergranular beta phase would be precipitated, therefore the intergranular beta phase keeps the same orientation with the parental beta phase. Once the alloy was heat treated at 975 degrees C close to T-beta, the microstructure is characterized by primary alpha variants selection and a large amount of secondary a widmanstatten structure with a homogeneous orientation which accounts for the lowest tensile strength. The decomposition of twelve alpha variants proved the BOR <110>(beta)//(0001)(alpha), <111>(beta)//<2-1-10>(alpha). The misorientation between two variants sharing a common parental <100>(beta) pole with a similar color consisting of all Euler angles was identified to be [0001] (alpha)/10.53 degrees.

  • 102007. Yang, Y.
    et al.
    Zhang, Y.
    Fang, L.
    Halloran, M. E.
    Ma, M.
    Liang, S.
    Kenah, E.
    Britton, Tom
    Stockholm University, Faculty of Science, Department of Mathematics.
    Chen, E.
    Hu, J.
    Tang, F.
    Cao, W.
    Feng, Z.
    Longini, I. M., Jr.
    Household transmissibility of avian influenza A (H7N9) virus, China, February to May 2013 and October 2013 to March 20142015In: Eurosurveillance, ISSN 1025-496X, E-ISSN 1560-7917, Vol. 20, no 10, article id 21056Article in journal (Refereed)
    Abstract [en]

    To study human-to-human transmissibility of the avian influenza A (H7N9) virus in China, household contact information was collected for 125 index cases during the spring wave (February to May 2013), and for 187 index cases during the winter wave (October 2013 to March 2014). Using a statistical model, we found evidence for human-to-human transmission, but such transmission is not sustainable. Under plausible assumptions about the natural history of disease and the relative transmission frequencies in settings other than household, we estimate the household secondary attack rate (SAR) among humans to be 1.4% (95% CI: 0.8 to 2.3), and the basic reproductive number R0 to be 0.08 (95% CI: 0.05 to 0.13). The estimates range from 1.3% to 2.2% for SAR and from 0.07 to 0.12 for R0 with reasonable changes in the assumptions. There was no significant change in the human-to-human transmissibility of the virus between the two waves, although a minor increase was observed in the winter wave. No sex or age difference in the risk of infection from a human source was found. Human-to-human transmissibility of H7N9 continues to be limited, but it needs to be closely monitored for potential increase via genetic reassortment or mutation.

  • 102008. Yang, Y.
    et al.
    Östlin, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    IMAGES. I. Strong evolution of galaxy kinematics since z = 12008In: Astronomy and Astrophysics, Vol. 477, p. 789-Article in journal (Other (popular science, discussion, etc.))
  • 102009.
    Yang, Ye
    et al.
    Nanyang Technological University, Singapore.
    Lyubartsev, Alexander
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Department of Physical Chemistry. Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Korolev, Nikolai
    Nanyang Technological University, Singapore.
    Nordenskiöld, Lars
    Nanyang Technological University, Singapore.
    Computer Modeling Reveals that Modifications of the Histone Tail Charges Define Salt-Dependent Interaction of the Nucleosome Core Particles2009In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 96, p. 2082-2096Article in journal (Refereed)
    Abstract [en]

    Coarse-grained Langevin molecular dynamics computer simulations were conducted for systems that mimic solutions of nucleosome core particles (NCPs). The NCP was modeled as a negatively charged spherical particle representing the complex of DNA and the globular part of the histones combined with attached strings of connected charged beads modeling the histone tails. The size, charge, and distribution of the tails relative to the core were built to match real NCPs. Three models of NCPs were constructed to represent different extents of covalent modification on the histone tails: (nonmodified) recombinant (rNCP), acetylated (aNCP), and acetylated and phosphorylated (paNCP). The simulation cell contained 10 NCPs in a dielectric continuum with explicit mobile counterions and added salt. The NCP-NCP interaction is decisively dependent on the modification state of the histone tails and on salt conditions. Increasing the monovalent salt concentration (KCl) from salt-free to physiological concentration leads to NCP aggregation in solution for rNCP, whereas NCP associates are observed only occasionally in the system of aNCPs. In the presence of divalent salt (Mg2+), rNCPs form dense stable aggregates, whereas aNCPs form aggregates less frequently. Aggregates are formed via histone-tail bridging and accumulation of counterions in the regions of NCP-NCP contacts. The paNCPs do not show NCP-NCP interaction upon addition of KCl or in the presence of Mg2+. Simulations for systems with a gradual substitution of K+ for Mg2+, to mimic the Mg2+ titration of an NCP solution, were performed. The rNCP system showed stronger aggregation that occurred at lower concentrations of added Mg2+, compared to the aNCP system. Additional molecular dynamics simulations performed with a single NCP in the simulation cell showed that detachment of the tails from the NCP core was modest under a wide range of salt concentrations. This implies that salt-induced tail dissociation of the histone tails from the globular NCP is not in itself a major factor in NCP-NCP aggregation. The approximation of coarse-graining, with respect to the description of the NCP as a sphere with uniform charge distribution, was tested in control simulations. A more detailed description of the NCP did not change the main features of the results. Overall, the results of this work are in agreement with experimental data reported for NCP solutions and for chromatin arrays.

  • 102010. Yang, Yi
    et al.
    Hashimoto, Jun
    Hayashi, Saeko S.
    Tamura, Motohide
    Mayama, Satoshi
    Rafikov, Roman
    Akiyama, Eiji
    Carson, Joseph C.
    Janson, Markus
    Stockholm University, Faculty of Science, Department of Astronomy.
    Kwon, Jungmi
    De Leon, Jerome
    Oh, Daehyeon
    Takami, Michihiro
    Tang, Ya-Wen
    Kudo, Tomoyuki
    Kusakabe, Nobuhiko
    Abe, Lyu
    Brandner, Wolfgang
    Brandt, Timothy D.
    Egner, Sebastian
    Feldt, Markus
    Goto, Miwa
    Grady, Carol A.
    Guyon, Olivier
    Hayano, Yutaka
    Hayashi, Masahiko
    Henning, Thomas
    Hodapp, Klaus W.
    Ishii, Miki
    Iye, Masanori
    Kandori, Ryo
    Knapp, Gillian R.
    Kuzuhara, Masayuki
    Matsuo, Taro
    Mcelwain, Michael W.
    Miyama, Shoken
    Morino, Jun-Ichi
    Moro-Martin, Amaya
    Nishimura, Tetsuo
    Pyo, Tae-Soo
    Serabyn, Eugene
    Suenaga, Takuya
    Suto, Hiroshi
    Suzuki, Ryuji
    Takahashi, Yasuhiro H.
    Takato, Naruhisa
    Terada, Hiroshi
    Thalmann, Christian
    Turner, Edwin L.
    Watanabe, Makoto
    Wisniewski, John
    Yamada, Toru
    Takami, Hideki
    Usuda, Tomonori
    NEAR-INFRARED IMAGING POLARIMETRY OF INNER REGION OF GG TAU A DISK2017In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 153, no 1, article id 7Article in journal (Refereed)
    Abstract [en]

    By performing non-masked polarization imaging with Subaru/HiCIAO, polarized scattered light from the inner region of the disk around the GG Tau A system was successfully detected in the H band, with a spatial resolution of approximately 0 07, revealing the complicated inner disk structures around this young binary. This paper reports the observation of an arc-like structure to the north of GG Tau Ab, and part of a circumstellar structure that is noticeable around GG Tau Aa, extending to a distance of approximately 28 au from the primary star. The speckle noise around GG Tau Ab constrains its disk radius to < 13 au. Based on the size of the circumbinary ring and the circumstellar disk around GG Tau Aa, the semimajor axis of the binary's orbit is likely to be 62 au. A comparison of the present observations with previous Atacama Large Millimeter Array and near-infrared H-2 emission observations suggests that the north arc could be part of a large streamer flowing from the circumbinary ring to sustain the circumstellar disks. According to the previous studies, the circumstellar disk around GG Tau Aa has enough mass and can sustain itself for a duration sufficient for planet formation; thus, our study indicates that planets can form within close (separation. 100 au) young binary systems.

  • 102011. Yang, Yi
    et al.
    Mayama, Satoshi
    Hayashi, Saeko S.
    Hashimoto, Jun
    Rafikov, Roman
    Akiyama, Eiji
    Currie, Thayne
    Janson, Markus
    Stockholm University, Faculty of Science, Department of Astronomy.
    Momose, Munetake
    Nakagawa, Takao
    Oh, Daehyeon
    Kudo, Tomoyuki
    Kusakabe, Nobuhiko
    Abe, Lyu
    Brandner, Wolfgang
    Brandt, Timothy D.
    Carson, Joseph C.
    Egner, Sebastian
    Feldt, Markus
    Goto, Miwa
    Grady, Carol A.
    Guyon, Olivier
    Hayano, Yutaka
    Hayashi, Masahiko
    Henning, Thomas
    Hodapp, Klaus W.
    Ishii, Miki
    Iye, Masanori
    Kandori, Ryo
    Knapp, Gillian R.
    Kwon, Jungmi
    Kuzuhara, Masayuki
    Matsuo, Taro
    Mcelwain, Michael W.
    Miyama, Shoken
    Morino, Jun-Ichi
    Moro-martin, Amaya
    Nishimura, Tetsuo
    Pyo, Tae-Soo
    Serabyn, Eugene
    Suenaga, Takuya
    Suto, Hiroshi
    Suzuki, Ryuji
    Takahashi, Yasuhiro H.
    Takami, Michihiro
    Takato, Naruhisa
    Terada, Hiroshi
    Thalmann, Christian
    Turner, Edwin L.
    Watanabe, Makoto
    Wisniewski, John
    Yamada, Toru
    Takami, Hideki
    Usuda, Tomonori
    Tamura, Motohide
    High-contrast Polarimetry Observation of the T Tau Circumstellar Environment2018In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 861, no 2, article id 133Article in journal (Refereed)
    Abstract [en]

    We conducted high-contrast polarimetry observations of T Tau in the H-band, using the High Contrast Instrument for the Subaru Next Generation Adaptive Optics instrument mounted on the Subaru Telescope, revealing structures as near as 0 1 from the stars T Tau N and T Tau S. The whole T Tau system is found to be surrounded by nebulalike envelopes, and several outflow-related structures are detected in these envelopes. We analyzed the detailed polarization patterns of the circumstellar structures near each component of this triple young star system and determined constraints on the circumstellar disks and outflow structures. We suggest that the nearly face-on circumstellar disk of T Tau N is no larger than 0.''8, or 117 au, in the northwest, based on the existence of a hole in this direction, and no larger than 0.''27, or 40 au, in the south. A new structure, N5, extends to about 0.''42, or 59 au, southwest of the star, and is believed to be part of the disk. We suggest that T Tau S is surrounded by a highly inclined circumbinary disk with a radius of about 0.''3, or 44 au, with a position angle of about 30 degrees, that is misaligned with the orbit of the T Tau S binary. After analyzing the positions and polarization vector patterns of the outflow-related structures, we suggest that T Tau S should trigger the well-known E-W outflow, and is also likely to be responsible for a southwest precessing outflow coil and a possible south outflow.

  • 102012.
    Yang, Yi
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Changzhou Vocational Institute of Engineering, China.
    Shen, Kang
    Lin, Jun-Zhong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhou, Yong
    Liu, Qiao-yun
    Hang, Cheng
    Abdelhamid, Hani Nasser
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhang, Zhen-qin
    Chen, Hong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). KTH Royal Institute of Technology, Sweden.
    A Zn-MOF constructed from electron-rich pi-conjugated ligands with an interpenetrated graphene-like net as an efficient nitroaromatic sensor2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 51, p. 45475-45481Article in journal (Refereed)
    Abstract [en]

    A novel zinc-based luminescent metal-organic framework (Zn-MOF) has been successfully constructed based on a designed flexible and electron-rich N-involved linker (HL = 4-(bis(4-(pyridin-4-yl) phenyl) amino) benzoic acid). The framework of this Zn-MOF exhibits a 2-fold interpenetrated network which is composed of (3,3)-c sheets. The Zn-MOF has a strong solid state emission at 512 nm. The luminescence signal of the Zn-MOF can be quenched efficiently by trace amounts of electron-deficient nitroaromatics, especially 2,4,6-trinitrophenol (TNP). The quenching constant (K-sv) for TNP is 2.11 x 10(4) M-1, indicating that this framework can be employed as an excellent chemical sensor for identifying and quantifying TNP. This work highlights a strategy for designing a N-involved p-electron-rich enhanced ligand with nucleophilic properties for MOF-based materials as sensors. It also paves the way toward exploring other more efficient MOF materials as sensors for determining electron-deficient nitroaromatics.

  • 102013.
    Yang, Yuzhu
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of Allenes by Catalytic Coupling of Propargyl Carbonates with Aryl Iodides in the Presence of Diboron Species2016In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 81, no 1, p. 250-255Article in journal (Refereed)
    Abstract [en]

    Bimetallic copper-/palladium-catalyzed multicomponent reaction of propargyl carbonates, aryl iodides, and diboron species was studied. This procedure can be used for synthesis of di-, tri-, and tetra-substituted allenes. Using diboronic acid, the reaction is supposed to proceed via allenylboronic acid intermediate.

  • 102014. Yang, Zhi-Yin
    et al.
    Yang, Zhen
    Zhu, Lifang
    Qiu, Chengxuan
    Stockholm University, Faculty of Social Sciences, Aging Research Center (ARC), (together with KI).
    Human Behaviors Determine Health: Strategic Thoughts on the Prevention of Chronic Non-communicable Diseases in China2011In: International Journal of Behavioral Medicine, ISSN 1070-5503, E-ISSN 1532-7558, Vol. 18, no 4, p. 295-301Article in journal (Refereed)
    Abstract [en]

    In the last three decades, people's living standards have significantly increased along with the rapid growth of the national economy of China. However, the prevalence of unhealthy behaviors and unfavorable lifestyles (e.g., smoking, excessive use of alcohol, physical inactivity, and unhealthy diets) also steadily increased, which may contribute to the growing epidemic of chronic non-communicable diseases (CNCDs) such as diabetes, coronary heart disease, stroke, and cancers. To briefly summarize the major studies from China concerning epidemic and burden of CNCDs and unhealthy lifestyles, and propose intervention strategies toward unhealthy lifestyles and behaviors aiming for effective control of the growing epidemic of CNCDs in China. We first review the major national studies addressing the epidemic and burden of CNCDs and unhealthy behaviors in China. Then, we aim to develop the preventive strategies against the increasing epidemic of CNCDs by focusing on the intervention campaign toward health unfavorable behaviors and lifestyles. CNCDs have posed major challenges to public health and the ongoing reform of health care system in China. Unhealthy lifestyles and behaviors (e.g., smoking, excessive alcohol consumpsion, physical inactivity, and imbalanced diets) are responsible for the growing epidemic of CNCDs. Adherence to healthy behaviors and lifestyles is critical for maintaining physical and mental health. Active implementation of the population-wide intervention program of health education and promotion by targeting unhealthy behaviors and lifestyles may help to constrain the growing epidemic of CNCDs in China.

  • 102015.
    Yao, Ke
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Fudan University, China; Ministry of Education, China.
    Schuch, Reinhold
    Stockholm University, Faculty of Science, Department of Physics.
    Evaporative cooling of hydrogen molecular ions in a Penning trap2014In: Hyperfine interactions, 2014, Vol. 227, no 1-3, p. 191-196Conference paper (Refereed)
    Abstract [en]

    Evaporative cooling of singly charged ions in a Penning trap is studied. The ions are created by in-situ electron bombardment of hydrogen molecules and trapped in a cylindrical Penning trap. Cooling of the ions is observed by their axial motion after trapping of a few hundred milliseconds. The ions temperature decreases by a factor of more than 6 in 800 ms, while the bunch density of the coldest ions increases by up to a factor of 10. By studying the time constants of the dependence of ion loss and axial temperature on the magnetic field strength, we exclude the effects of ions loss through the cyclotron motion on the axial ion temperature.

  • 102016. Yao, Lei
    et al.
    Garmash, Olga
    Bianchi, Federico
    Zheng, Jun
    Yan, Chao
    Kontkanen, Jenni
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. University of Helsinki, Finland.
    Junninen, Heikki
    Mazon, Stephany Buenrostro
    Ehn, Mikael
    Paasonen, Pauli
    Sipilä, Mikko
    Wang, Mingyi
    Wang, Xinke
    Xiao, Shan
    Chen, Hangfei
    Lu, Yiqun
    Zhang, Bowen
    Wang, Dongfang
    Fu, Qingyan
    Geng, Fuhai
    Li, Li
    Wang, Hongli
    Qiao, Liping
    Yang, Xin
    Chen, Jianmin
    Kerminen, Veli-Matti
    Petäjä, Tuukka
    Worsnop, Douglas R.
    Kulmala, Markku
    Wang, Lin
    Atmospheric new particle formation from sulfuric acid and amines in a Chinese megacity2018In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 361, no 6399, p. 278-281Article in journal (Refereed)
    Abstract [en]

    Atmospheric new particle formation (NPF) is an important global phenomenon that is nevertheless sensitive to ambient conditions. According to both observation and theoretical arguments, NPF usually requires a relatively high sulfuric acid (H2SO4) concentration to promote the formation of new particles and a low preexisting aerosol loading to minimize the sink of new particles. We investigated NPF in Shanghai and were able to observe both precursor vapors (H2SO4) and initial clusters at a molecular level in a megacity. High NPF rates were observed to coincide with several familiar markers suggestive of H2SO4-dimethylamine (DMA)water (H2O) nucleation, including sulfuric acid dimers and H2SO4-DMA clusters. In a cluster kinetics simulation, the observed concentration of sulfuric acid was high enough to explain the particle growth to similar to 3 nanometers under the very high condensation sink, whereas the subsequent higher growth rate beyond this size is believed to result fromthe added contribution of condensing organic species. These findings will help in understanding urban NPF and its air quality and climate effects, as well as in formulating policies to mitigate secondary particle formation in China.

  • 102017.
    Yao, Liqun
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Genome-wide identification of Grainy head target genes and their functions in Drosophila embryos2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The transcription factor Grainy head (Grh) is conserved from Drosophila to humans. Drosophila Grh plays important roles in epithelial differentiation and regeneration. To investigate the mechanisms of Grh function, we performed ChIP-sequencing and microarray gene expression analysis and identified Grh target genes in Drosophila embryos at a genome-wide scale. We found Grh ChIP peaks in the proximity of 3754 genes and showed that Grh acts both as an activator and as a repressor. 

    Grh regulates distinct genes in different contexts. During wound healing, Grh transcriptionally activates stitcher (stit), a gene encoding a receptor tyrosine kinase. We show that Stit activates two distinct pathways, including Src kinases and extracellular signal-regulated kinase (ERK), after injury. The tyrosine residue Y762 mediates Stit binding to the SH2 domains of Src42A, Src64B, or Drk. Src family kinases and Drk act as downstream effectors of Stit in the activation of wound response enhancers. Src family kinases control re-epithelialization, but fail to induce the dpERK accumulation after injury. In contrast, Drk is dispensable in re-epithelialization, but can induce the activation of ERK, which can therefore link RTKs to ERK-mediated Grh-dependent activation of wound response genes. In airways, Grh regulates 1152 target genes encoding various enzymes, signaling proteins, and transcription factors. Grh represses the POU-domain transcription factor Vvl (Ventral veinless). Vvl interacts with Grh and can regulate a set of Grh target genes. Grh and Vvl antagonize each other during airway maturation and tracheal tube elongation. The analysis of Grh-responsive enhancers during embryonic development and in wound healing indicates that Grh cooperates with other transcription factors, such as Vvl, to regulate target gene expression.

    In addition, we identify a novel grh PO isoform expressed predominantly in the central nervous system, epidermis, and trachea. Unlike the canonical grh (grh PI) that can regulate endogenous grh PI and grh PO, Grh PO fails to regulate the grh gene transcriptionally. Further functional analysis in the trachea suggests that Grh PO may act as a partial dominant-negative regulator of Grh.

  • 102018.
    Yao, Liqun
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Guo, Enen
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Samakovlis, Christos
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Stockholm University, Science for Life Laboratory (SciLifeLab). Universities of Giessen and Marburg Lung Center (UGMLC), Germany.
    A new grh isoform in Drosophila and functional analysis of Grh domains in DrosophilaManuscript (preprint) (Other academic)
  • 102019.
    Yao, Liqun
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Wang, Shenqiu
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Sloan Kettering Institute, USA.
    Dai, Qi
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Sloan Kettering Institute, USA.
    Orzechowski-Westholm, Jakub
    Matsuda, Ryo
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Hosono, Chie
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Bray, Sarah
    Lai, Eric C.
    Samakovlis, Christos
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Stockholm University, Science for Life Laboratory (SciLifeLab). Universities of Giessen and Marburg Lung Center (UGMLC), Germany.
    Genome-wide identification of Grainy head target genes in Drosophila reveals complex regulatory interactions between Grh and the POU-domain transcription factor, VvlManuscript (preprint) (Other academic)
  • 102020.
    Yao, Liqun
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Wang, Shenqiu
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Sloan-Kettering Institute, USA.
    Westholm, Jakub O.
    Dai, Qi
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Sloan-Kettering Institute, USA.
    Matsuda, Ryo
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Hosono, Chie
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Bray, Sarah
    Lai, Eric C.
    Samakovlis, Christos
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Stockholm University, Science for Life Laboratory (SciLifeLab). UGMLC, Germany.
    Genome-wide identification of Grainy head targets in Drosophila reveals regulatory interactions with the POU domain transcription factor Vvl2017In: Development, ISSN 0950-1991, E-ISSN 1477-9129, Vol. 144, no 17, p. 3145-3155Article in journal (Refereed)
    Abstract [en]

    Grainy head (Grh) is a conserved transcription factor (TF) controlling epithelial differentiation and regeneration. To elucidate Grh functions we identified embryonic Grh targets by ChIP-seq and gene expression analysis. We show that Grh controls hundreds of target genes. Repression or activation correlates with the distance of Grh-binding sites to the transcription start sites of its targets. Analysis of 54 Grh-responsive enhancers during development and upon wounding suggests cooperation with distinct TFs in different contexts. In the airways, Grh-repressed genes encode key TFs involved in branching and cell differentiation. Reduction of the POU domain TF Ventral veins lacking (Vvl) largely ameliorates the airway morphogenesis defects of grh mutants. Vvl and Grh proteins additionally interact with each other and regulate a set of common enhancers during epithelial morphogenesis. We conclude that Grh and Vvl participate in a regulatory network controlling epithelial maturation.

  • 102021.
    Yao, Qingxia
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bermejo Gómez, Antonio
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Pascanu, Vlad
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Yun, Yifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zheng, Haoquan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Chen, Hong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Liu, Leifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Abdelhamid, Hani Nasser
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Martin-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Series of Highly Stable Isoreticular Lanthanide Metal-Organic Frameworks with Expanding Pore Size and Tunable Luminescent Properties2015In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 15, p. 5332-5339Article in journal (Refereed)
    Abstract [en]

    A series of highly porous isoreticular lanthanide-based metal organic frameworks (LnMOFs) denoted as SUMOE-7I to SUMOE-7IV (SU = Stockholm University; Ln = La, Ce, Pr, Nd, Sm, Eu, and Gd) have been synthesized using tritopic carboxylates as the organic linkers. The SUMOF-7 materials display one-dimensional pseudohexagonal channels with the pore diameter gradually enlarged from 8.4 to 23.9 angstrom, as a result of increasing sizes of the organic linkers. The structures have been solved by single crystal X-ray diffraction or rotation electron diffraction (RED) combined with powder X-ray diffraction (PXRD). The SUMOF-7 materials exhibit robust architectures with permanent porosity. More importantly, they exhibit exceptionally high thermal and chemical stability. We show that, by inclusion of organic dye molecules, the luminescence properties of the MOFs can be elaborated and modulated, leading to promising applications in sensing and optics.

  • 102022.
    Yao, Qingxia
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Bermejo Gómez, Antonio
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Pascanu, Vlad
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Yun, Yifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zheng, Haoquan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Chen, Hong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Liu, Leifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Highly porous isoreticular lanthanide metal-organic frameworksManuscript (preprint) (Other academic)
    Abstract [en]

    As an emerging type of porous materials, metal–organic frameworks (MOFs) have the advantages over conventional inorganic porous materials in that their structures and functions are systematically and predictably designable. Isoreticular expansion is an efficient way for systematic design and control of pore size and shape for MOFs. By using our proposed strategy, a series of highly porous isoreticular lanthanide-based metal-organic frameworks with systematic pore apertures has been obtained, which afford an isoreticular series of MIL-103 structures (termed SUMOF-7I to IV) with pore apertures ranging from 7.2 Å to 23 Å. These materials demonstrated exhibit robust architectures with permanent porosity, and exceptional thermal stability and chemical stability in various solvents. The combination of luminescence property and significant porosity of these MOFs enable them as a potential platform for multifunctional purpose.

  • 102023. Yao, Qingxia
    et al.
    Su, Jie
    Cheung, Ocean
    Liu, Qingling
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Interpenetrated metal-organic frameworks and their uptake of CO2 at relatively low pressures2012In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 22, no 20, p. 10345-10351Article in journal (Refereed)
    Abstract [en]

    Adsorption-driven separation of CO2 from flue gas has the potential to cut the cost for carbon capture and storage. Among the porous physisorbents, metal-organic frameworks (MOFs) are a class of promising candidates for gas separation and storage owing to their extraordinarily high specific surface areas and pore volumes, and predesigned pore structures. Here, we report three interpenetrated MOFs composed of Zn4O clusters and rigid dicarboxylate anions, namely SUMOF-n (SU StockholmUniversity; n = 2, 3, 4). All the interpenetrated MOFs possess small pores of two different types and high pore volumes. SUMOF-2 had a structure similar to interpenetrated MOF-5, but with an extra-framework cation present in one of the two types of pores. SUMOF-3 was an interpenetrated version of IRMOF-8 while SUMOF-4 crystallized with mixed linkers, biphenyl-4,4'-dicarboxylic acid and benzene-1,4-dicarboxylic acid. Among the three SUMOFs, SUMOF-4 had the largest specific surface area (1612 m(2) g(-1)) and pore volume. Single component adsorption of CO2 and N-2 was determined at 273 K. We showed that the interpenetrated SUMOF-2 adsorbedmore CO2 than non-interpenetrated MOF-5 under 273 K and 1 bar. This may be explained by the increased electric field gradients due to the interpenetration in the MOF. The uptake of CO2 for SUMOF-2 and SUMOF-4 was significant at somewhat higher pressure. Their CO2 isotherms were close to linear, which could be beneficial for separation of CO2 via pressure swing adsorption from biogas or natural gas. On the other hand, SUMOF-3 adsorbed most CO2 at pressures relevant for CO2 capture from flue gas.

  • 102024. Yao, Qingxia
    et al.
    Su, Jie
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    SUMOF-5: a mesoporous metal-organic framework with the tbo topology built from the dicopper paddle-wheel cluster and a new tritopic linker2013In: Zeitschrift fur Kristallographie, ISSN 0044-2968, Vol. 228, no 7, p. 323-329Article in journal (Refereed)
    Abstract [en]

    A mesoporous metal-organic framework Cu-3(PTB)(2)(H2O)(3) center dot guest (denoted as SUMOF-5) has been synthesized using a new tritopic linker pyridine-2,4,6-tribenzoic acid (H3PTB). SUMOF-5 is cubic with the space group Fm (3) over barm and a = 47.272(3) angstrom. The framework is built of the dicopper paddle-wheel secondary building unit (SBU) [Cu-2(OOC)(4)(H2O)(2)] and contains two different cavities of 1.22 and 2.33 nm in diameter, respectively. The framework topology follows the (3,4)-connected tbo net, and can be regarded as an extended version of Cu-3(BTC)(2)(H2O)(3) center dot guest (HKUST-1, BTC = benzene tricarboxylate). The structure of SUMOF-5 is compared to other MOFs built from dicopper paddle-wheels and tritopic linkers. SUMOF-5 has permanent porosity with a Langmuir surface area of 1733 m(2)/g and is stable in various organic solvents, which makes this material potentially useful as a crystalline carrier for loading molecular catalysts or drugs.

  • 102025.
    Yao, Qingxia
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Li, Kuo
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Peskov, Maxim V.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    A series of isostructural mesoporous metal-organic frameworks obtained by ion-exchange induced single-crystal to single-crystal transformation2012In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 41, no 14, p. 3953-3955Article in journal (Refereed)
    Abstract [en]

    A series of metal-organic frameworks representing a non-interpenetrated framework analogue of MOF-14 have been synthesized by using two different linkers, 4,4',4 ''-benzene-1,3,5-triyl-benzoic acid (H3BTB) and 4,4'-bipyridine (Bpy). Interestingly, the transition metal ions in the paddle-wheel metal clusters could be exchanged by other transition metal ions via a direct single-crystal to single-crystal transformation. This post-synthesis route can be used for synthesis of isomorphous metal-organic frameworks that cannot be obtained by direct synthesis.

  • 102026. Yao, Shuyang
    et al.
    Långström, Niklas
    Temrin, Hans
    Stockholm University, Faculty of Science, Department of Zoology.
    Walum, Hasse
    Criminal offending as part of an alternative reproductive strategy: investigating evolutionary hypotheses using Swedish total population data2014In: Evolution and human behavior, ISSN 1090-5138, E-ISSN 1879-0607, Vol. 35, no 6, p. 481-488Article in journal (Refereed)
    Abstract [en]

    Criminality is highly costly to victims and their relatives, but often also to offenders. From an evolutionary viewpoint, criminal behavior may persist despite adverse consequences by providing offenders with fitness benefits as part of a successful alternative mating strategy. Specifically, criminal behavior may have evolved as a reproductive strategy based on low parental investment reflected in low commitment in reproductive relationships. We linked data from nationwide total population registers in Sweden to test if criminality is associated with reproductive success. Further, we used several different measures related to monogamy to determine the relation between criminal behavior and alternative mating tactics. Convicted criminal offenders had more children than individuals never convicted of a criminal offense. Criminal offenders also had more reproductive partners, were less often married, more likely to get remarried if ever married, and had more often contracted a sexually transmitted disease than non-offenders. Importantly, the increased reproductive success of criminals was explained by a fertility increase from having children with several different partners. We conclude that criminality appears to be adaptive in a contemporary industrialized country, and that this association can be explained by antisocial behavior being part of an adaptive alternative reproductive strategy.

  • 102027. Yao, T.
    et al.
    Masson-Delmotte, V.
    Gao, J.
    Yu, W.
    Yang, X.
    Risi, C.
    Sturm, Christophe
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Werner, M.
    Zhao, H.
    He, Y.
    Ren, W.
    Tian, L.
    Shi, C.
    Hou, S.
    A review of climatic controls on δ18O in precipitation over the Tibetan Plateau: Observations and simulations2013In: Reviews of geophysics, ISSN 8755-1209, E-ISSN 1944-9208, Vol. 51, no 4, p. 2012RG000427-Article in journal (Refereed)
    Abstract [en]

    The stable oxygen isotope ratio (δ18O) in precipitation is an integrated tracer of atmospheric processes worldwide. Since the 1990s, an intensive effort has been dedicated to studying precipitation isotopic composition at more than 20 stations in the Tibetan Plateau (TP) located at the convergence of air masses between the westerlies and Indian monsoon. In this paper, we establish a database of precipitation δ18O and use different models to evaluate the climatic controls of precipitation δ18O over the TP. The spatial and temporal patterns of precipitation δ18O and their relationships with temperature and precipitation reveal three distinct domains, respectively associated with the influence of the westerlies (northern TP), Indian monsoon (southern TP), and transition in between. Precipitation δ18O in the monsoon domain experiences an abrupt decrease in May and most depletion in August, attributable to the shifting moisture origin between Bay of Bengal (BOB) and southern Indian Ocean. High-resolution atmospheric models capture the spatial and temporal patterns of precipitation δ18O and their relationships with moisture transport from the westerlies and Indian monsoon. Only in the westerlies domain are atmospheric models able to represent the relationships between climate and precipitation δ18O. More significant temperature effect exists when either the westerlies or Indian monsoon is the sole dominant atmospheric process. The observed and simulated altitude-δ18O relationships strongly depend on the season and the domain (Indian monsoon or westerlies). Our results have crucial implications for the interpretation of paleoclimate records and for the application of atmospheric simulations to quantifying paleoclimate and paleo-elevation changes.

  • 102028. Yao, Yuan
    et al.
    Hou, Meng-Shi
    Ong, Yen Chin
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Yangzhou University, China; Shanghai Jiao Tong University, China.
    A complementary third law for black hole thermodynamics2019In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 79, no 6, article id 513Article in journal (Refereed)
    Abstract [en]

    There are some examples in the literature, in which despite the fact that the underlying theory or model does not impose a lower bound on the size of black holes, the final temperature under Hawking evaporation is nevertheless finite and nonzero. We show that under some loose conditions, the black hole is necessarily an effective remnant, in the sense that its evaporation time is infinite. That is, the final state that there is nonzero finite temperature despite having no black hole remaining cannot be realized. We discuss the limitations, subtleties, and the implications of this result, which is reminiscent of the third law of black hole thermodynamics, but with the roles of temperature and size interchanged. We therefore refer to our result as the complementary third law for black hole thermodynamics.

  • 102029. Yaoquan, Tu
    et al.
    Laaksonen, Aatto
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Towards Fast and Reliable Quantum Chemical Modelling of Macromolecules2007In: New Algorithms for Macromolecular Simulation, 2007, p. 315-341Chapter in book (Refereed)
  • 102030. Yaoquan, Tu
    et al.
    Lennart, Nilsson
    Laaksonen, Aatto
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    A highly efficient ab initio tight-binding-like approximate density-functional2007In: Lecture Notes in Computer Science, 2007, p. 100-108Chapter in book (Refereed)
  • 102031.
    Yap, Kristiina
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Education.
    Song, Hellen
    Stockholm University, Faculty of Social Sciences, Department of Education.
    Leadership in a Cross-Cultural Context: A Qualitative Study of Cross-Cultural Leadership Competence in a Multinational Organization in China2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The essay aims to generate deeper understanding of leadership competences in a multinational organization in China, i.e. what competences that are required for managing professionals in a cross-cultural context. Previous research within this field of study discuss this topic from the perspective of Western or Chinese expatriate managers, but the authors of this study regard that it is of interest to study Chinese employees in a Western organization in China in order to understand how the global Western culture interacts with the local Chinese culture. The research questions were thus formulated to study what competences that are required in a managerial position in a multinational organization in China according to different organizational actors and documents, and what differences there are in the meaning of the various descriptions. The study has been conducted with a qualitative approach and the results indicate that To Manage, To Have Expertise and To Communicate are the most important competences needed in the managerial role. The results also indicate that the different sources are very similar in the description of cross-cultural leadership competence, which can be understood as the influence of a strong organizational culture. Finally, one can see that the younger employees differ slightly in expectations of leadership, which can be understood as leadership not being formed only by national culture but also by generational culture. In other words, the results from the study show that the meaning of cross-cultural leadership competence in this specific context is not merely restricted to the necessity of understanding national culture when exercising leadership; it is also about generational differences in culture.

  • 102032. Yar, M. A.
    et al.
    Wahlberg, Sverker
    Bergqivist, Hans
    Salem, H. G.
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Muhammed, Mamoun
    Spark plasma sintering of tungsten-yttrium oxide composites from chemically synthesized nanopowders and microstructural characterization2011In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 412, no 2, p. 227-232Article in journal (Refereed)
    Abstract [en]

    Nano-crystalline W-1%Y(2)O(3) (wt.%) powder was produced by a modified solution chemical reaction of ammonium paratungstate (APT) and yttrium nitrate. The precursor powder was found to consist of particles of bimodal morphology i.e. large APT-like particles up to 20 pm and rectangular yttrium containing ultrafine plates. After thermal processing tungsten crystals were evolved from W-O-Y plate like particles. spark plasma sintering (SPS) was used to consolidate the powder at 1100 and 1200 degrees C for different holding times in order to optimize the sintering conditions to yield high density but with reduced grain growth. Dispersion of yttrium oxide enhanced the sinterability of W powder with respect to lanthanum oxide. W-1%Y(2)O(3) composites with sub-micron grain size showed improved density and mechanical properties as compared to W-La(2)O(3) composites. Sample sintered in two steps showed improved density, due to longer holding time at lower temperature (900 degrees C) and less grain growth due to shorter holding time at higher temperature i.e. 1 min at 1100 degrees C.

  • 102033. Yar, Mazher Ahmed
    et al.
    Wahlberg, Sverker
    Abuelnaga, Mohammad Omar
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Muhammed, Mamoun
    Processing and sintering of yttrium-doped tungsten oxide nanopowders to tungsten-based composites2014In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 49, no 16, p. 5703-5713Article in journal (Refereed)
    Abstract [en]

    Innovative chemical methods are capable of fabricating nanoscale tungsten oxide compounds doped with various rare-earth elements with high purity and homogeneity, which can be processed under hydrogen into nanostructured oxide-dispersed tungsten composite powders having several potential applications. However, hydrogen reduction of doped tungsten oxide compounds is rather complex, affecting the morphology and composition of the final powder. In this study, we have investigated the reduction of tungstic acid in the presence of Y and we provide the experimental evidence that Y2O3 can be separated from Y-doped tungstic acid via hydrogen reduction to produce Y2O3-W powders. The processed powders were further consolidated by spark plasma sintering at different temperatures and holding times at 75 MPa pressure and characterized. The optimized SPS conditions suggest sintering at 1400 A degrees C for 3 min holding time to achieve higher density composites with an optimum finer grain size (3 A mu m) and a hardness value up to 420 H (V). Major grain growth takes place at temperatures above 1300 A degrees C during sintering. From the density values obtained, it is recommend to apply higher pressure before 900 A degrees C to obtain maximum density. Oxides inclusions present in the matrix were identified as Y2O3 center dot 3WO(3) and Y2O3 center dot WO3 during high resolution microscopic investigations.

  • 102034. Yar, Mazher Ahmed
    et al.
    Wahlberg, Sverker
    Bergqvist, Hans
    Salem, Hanadi G.
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Muhammed, Mamoun
    Chemically produced nanostructured ODS-lanthanum oxide-tungsten composites sintered by spark plasma2011In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 408, no 2, p. 129-135Article in journal (Refereed)
    Abstract [en]

    High purity W and W-0.9La(2)O(3) (wt.%) nanopowders were produced by a wet chemical route. The precursor was prepared by the reaction of ammonium paratungstate (APT) with lanthanum salt in aqueous solutions. High resolution electron microscopy investigations revealed that the tungstate particles were coated with oxide precipitates. The precursor powder was reduced to tungsten metal with dispersed lanthanum oxide. Powders were consolidated by spark plasma sintering (SPS) at 1300 and 1400 degrees C to suppress grain growth during sintering. The final grain size relates to the SPS conditions, i.e. temperature and heating rate, regardless of the starting powder particle size. Scanning electron microscopy revealed that oxide phases were mainly accumulated at grain boundaries while the tungsten matrix constituted of nanosized sub-grains. The transmission electron microscopy revealed that the tungsten grains consist of micron-scale grains and finer sub-grains. EDX analysis confirmed the presence of W in dispersed oxide phases with varying chemical composition, which evidenced the presence of complex oxide phases (WO-La) in the sintered metals.

  • 102035. Yarevsky, E.
    et al.
    Yakovlev, S. L.
    Elander, Nils
    Stockholm University, Faculty of Science, Department of Physics.
    Potential splitting approach to e-H and e-He+ scattering2017In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 50, no 5, article id 055001Article in journal (Refereed)
    Abstract [en]

    An approach based on splitting the reaction potential into a finite range part and a long range tail part to describe few-body scattering in the case of a Coulombic interaction is proposed. The solution to the Schrodinger equation for the long range tail of the reaction potential is used as an incoming wave. This reformulation of the scattering problem into an inhomogeneous Schrodinger equation with asymptotic outgoing waves makes it suitable for solving with the exterior complex scaling technique. The validity of the approach is analyzed from a formal point of view and demonstrated numerically, where the calculations are performed with the finite element method. The method of splitting the potential in this way is illustrated with calculations of the electron scattering on the hydrogen atom and the positive helium ion in energy regions where resonances appear.

  • 102036. Yarevsky, E.
    et al.
    Yakovlev, S. L.
    Elander, Nils
    Stockholm University, Faculty of Science, Department of Physics.
    Volkov, M. V.
    On the Scattering of the Electron off the Hydrogen Atom and the Helium Ion Below and Above the Ionization Threshold: Temkin-Poet Model2014In: Few-body systems, ISSN 0177-7963, E-ISSN 1432-5411, Vol. 55, no 8-10, p. 1057-1058Article in journal (Refereed)
    Abstract [en]

    We generalize here the splitting approach to the long range (Coulomb) interaction for the three body scattering problem. With this approach, the exterior complex rotation technique can be applied for systems with asymptotic Coulomb interaction. We illustrate the method with calculations of the electron scattering on the hydrogen atom and positive helium ion in the frame of the Temkin-Poet model.

  • 102037. Yarevsky, E.
    et al.
    Yakovlev, S. L.
    Larson, Åsa
    Stockholm University, Faculty of Science, Department of Physics.
    Elander, Nils
    Stockholm University, Faculty of Science, Department of Physics.
    Potential-splitting approach applied to the Temkin-Poet model for electron scattering off the hydrogen atom and the helium ion2015In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 48, no 11Article in journal (Refereed)
    Abstract [en]

    The study of scattering processes in few body systems is a difficult problem especially if long range interactions are involved. In order to solve such problems, we develop here a potential-splitting approach for three-body systems. This approach is based on splitting the reaction potential into a finite range core part and a long range tail part. The solution to the Schrodinger equation for the long range tail Hamiltonian is found analytically, and used as an incoming wave in the three body scattering problem. This reformulation of the scattering problem makes it suitable for treatment by the exterior complex scaling technique in the sense that the problem after the complex dilation is reduced to a boundary value problem with zero boundary conditions. We illustrate the method with calculations on the electron scattering off the hydrogen atom and the positive helium ion in the frame of the Temkin-Poet model.

  • 102038.
    Yaro, Walita
    Stockholm University, Faculty of Social Sciences, Stockholm Business School.
    The Role of Luxury Fashion Brands: A qualitative research of how the consumption of luxury fashion brands relate to young consumers' self-concept2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The market for luxury brands has outpaced other consumption categories through its growth, and has been found in continuous development. As there is an increasing amount of luxury categories, the consumption of luxury fashion brands account for the largest proportion of luxury profits, and the marketing costs for such brands has shown to surpass those of other fashion categories. Consumer researchers have throughout decades emphasized how individuals participate in consumption behavior to form their self-concept in relation to brands. However, previous research has disregarded the multidimensional perspective regarding the theory of self-concept when examining the consumption of brands. Hence, the current research paper aims to strengthen the existing self-concept theory by exploring the role in which luxury fashion brands have by focusing on how the consumption of such brands relate, and contribute, to the consumer’s self-concept. By applying a qualitative method to investigate such purpose, and involving the existing theory of self-concept, brand image, and brand personality, it appeared that luxury fashion brands has a function to operate as a confidence booster for young consumers’ perception of their self-concept. In terms of the theoretical contribution of this paper, this research further illustrates how the theoretical explanation of brand image and brand personality relates to two different dimensions of the consumer’s self-concept. The consumption of luxury fashion brands has shown a significant role in individuals’ consumption behavior by emphasizing a striving, and motivating, part in the self-concept of young consumers.

  • 102039. Yaron, O.
    et al.
    Perley, D. A.
    Gal-Yam, A.
    Groh, J. H.
    Horesh, A.
    Ofek, E. O.
    Kulkarni, S. R.
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Fransson, Claes
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Rubin, A.
    Szabo, P.
    Sapir, N.
    Taddia, Francesco
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cenko, S. B.
    Valenti, S.
    Arcavi, I.
    Howell, D. A.
    Kasliwal, M. M.
    Vreeswijk, P. M.
    Khazov, D.
    Fox, O. D.
    Cao, Y.
    Gnat, O.
    Kelly, P. L.
    Nugent, P. E.
    Filippenko, A. V.
    Laher, R. R.
    Wozniak, P. R.
    Lee, W. H.
    Rebbapragada, U. D.
    Maguire, K.
    Sullivan, M.
    Soumagnac, M. T.
    Confined dense circumstellar material surrounding a regular type II supernova2017In: Nature Physics, ISSN 1745-2473, E-ISSN 1745-2481, Vol. 13, no 5, p. 510-517Article in journal (Refereed)
    Abstract [en]

    With the advent of new wide-field, high-cadence optical transient surveys, our understanding of the diversity of core-collapse supernovae has grown tremendously in the last decade. However, the pre-supernova evolution of massive stars, which sets the physical backdrop to these violent events, is theoretically not well understood and difficult to probe observationally. Here we report the discovery of the supernova iPTF 13dqy = SN 2013fs a mere similar to 3 h after explosion. Our rapid follow-up observations, which include multiwavelength photometry and extremely early (beginning at similar to 6 h post-explosion) spectra, map the distribution of material in the immediate environment (less than or similar to 1015 cm) of the exploding star and establish that it was surrounded by circumstellar material (CSM) that was ejected during the final similar to 1 yr prior to explosion at a high rate, around 10(-3) solar masses per year. The complete disappearance of flash-ionized emission lines within the first several days requires that the dense CSM be confined to within less than or similar to 10(15) cm, consistent with radio non-detections at 70-100 days. The observations indicate that iPTF 13dqy was a regular type II supernova; thus, the finding that the probable red supergiant progenitor of this common explosion ejected material at a highly elevated rate just prior to its demise suggests that pre-supernova instabilities may be common among exploding massive stars.

  • 102040. Yartys, V.
    et al.
    Noréus, Dag
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Latroche, M.
    Metal hydrides as negative electrode materials for Ni-MH batteries2016In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 122, no 1Article in journal (Refereed)
    Abstract [en]

    Structural, thermodynamical and electrochemical properties of metallic hydrides belonging to the pseudo-binary family A-Mg-Ni (A: rare earths) are reviewed and compared. Technology aspects of bipolar cells are also discussed.

  • 102041.
    Yasasindhu, Roy
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Ser sambandet mellan korrekthet och säkerhet olika ut för minnen för emotionella och neutralahändelser?2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med föreliggande studie är att testa om det finns en skillnadmellan säkerhet och korrekthet vid observation av en emotionell ochen neutral händelse. Ett annat syfte var att se om säkerhetenpåverkades positivt av bra minnesprestation. Ett experiment utfördesmed ett urval på 43 studenter där undersökningsdeltagarna fick se ettfilmklipp med antingen emotionellt eller neutralt innehåll, därefterintervjuades de angående innehållet i filmklippet och slutligen ombadsde att skatta säkerheten av varje påstående. Resultaten visade attsäkerheten vid korrekta svar var signifikant högre än vid felaktigasvar. Skillnad i säkerhet mellan emotionell och neutral observation varicke-signifikant och kunde antas bero på ett otillräckligt emotionelltinnehåll i filmklippet, eller den trygga experimentmiljön. Skillnaden isäkerheten vid korrekta och felaktiga svar gav stöd till tidigare studiersom visade att säkerheten var högre vid korrekta svar.

  • 102042. Yaseen, Najel
    et al.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Jarrar, Ghaleb H.
    Whitehouse, Martin
    U-Pb detrital zircon provenance of the Saramuj Conglomerate, Jordan, and implications for the Neoproterozoic evolution of the Red Sea region2013In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 239, p. 6-23Article in journal (Refereed)
    Abstract [en]

    The latest stage in the evolution of the northernmost Arabian-Nubian Shield is characterized by the development of volcano-sedimentary successions. In Jordan the Saramuj Conglomerate Formation is considered to be one of these post-tectonic basins. It is polymict and poorly sorted with wide range of clast compositions, roundness and size. We present the first SIMS U-Pb dating of detrital zircons from two sandstone samples representative for the conglomerate matrix and of four clasts from the Saramuj Conglomerate for provenance and age determinations. The relative probability curve for the matrix samples indicates a major contribution (85%) from c. 600 to 650 Ma, subclusters at 624 and 640 Ma, a minor source from 700 to 750 Ma, and a clear gap between 650 and 700 Ma. These ages are consistent with those obtained from andesitic, rhyodacitic, granitic and gneiss clasts (624, 642,650 and 734 Ma respectively). In contrast to the adjacent volcano-sedimentary successions in the Elat area, Sinai and the Eastern Desert, no ages older than 750 Ma were found. The good match between the known ages of the nearby exposed basement with the matrix ages and the immature nature of the sediments implies that the principal input was locally derived erosional detritus. The age of the youngest 10 detrital zircons at C. 615 Ma represents the maximum age of deposition, which is consistent with the stratigraphic position of the Saramuj Conglomerate. Clast ages of 642 Ma and 650 Ma are interpreted as evidence for a magmatic source that has not been recognized in SW Jordan. This study implies that the volcano-sedimentary successions in the northernmost Arabian-Nubian shield may be broadly coeval but have distinct provenance and therefore evolved as isolated basins. Furthermore, U-Pb zircon provenance analysis allows us to recognize igneous products that are no longer preserved and/or exposed in the region.

  • 102043.
    Yashkina, Svetlana
    Stockholm University, Faculty of Humanities, Department of Culture and Aesthetics.
    Modern Fairy Tales: The New Existence of an Old Genre: Exemplified by the Books of Alan A. Milne, Tove Jansson and Eno Raud2016Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this study is to draw new perspectives to the theoretic approach towards the complex nature of the modern fairy tale genre and its transformation. The study is exemplified by two books by Alan A. Milne about Winnie-the-Pooh (1926-1928), Tove Jansson’s eight books about the Moomintrolls (1945-1970) and Eno Raud’s four books about three funny creatures called “Nakstitrallid” in Estonian (1972-1982).

    In this thesis, I examine the disputable problem of defining the fairy tale genre in modern literature and refer to the history of the genre and storytelling tradition that have indirectly inspired all three authors in their decision to turn for fairy tale as a genre. Applying the poetical analysis, I argue that these authors contributed to the continuity of fairy tales by creating the link between folkloric heritage, novelistic literary expression and children’s imagination. This study can therefore be considered as topological, however it does not pretend to introduce the complete systematic definition of the genre as the thesis’ format does not allow such in-depth investigation.

    In the first chapter, ‘Archaic world stimulation in modern fairy tale’, I examine the dominating literary categories that refer to the folk fairy tale intertext: Bakhtin’s concept of ‘chronotope’ – category of time and space, system of fictional allegoric characters and category of fantastic. 

    In the second chapter, ‘Modern fairy tales from perspective of children’s literature’, I analyze the books of Milne, Jansson and Raud in the scope of narratological and aesthetic categories of children’s literature. The folkloric laughter intertextually reproduced by naïvism of the Moomins, the Naksitralls, and Winnie-the-Pooh’s friends, while folkloric collective hero is presented by universal harmony of a happy family and child-like protagonists.

    I came to the conclusion that poetics of folklore fairy tale still exists in these books through the intertextual dialogue. Modernism as literary method re-evaluates folkloric aspects such as nonlinear time, the blurred boarders between individual and cosmos, material and spirit, text and reality. Every new artistically unique fairy tale world resembles the new stage of the genre development. The more innovative is the story, the more sophisticated can be its poetics.

  • 102044.
    Yassarati, Annahita
    Stockholm University, Faculty of Social Sciences, Department of Sociology.
    Den kompetenta personalvetaren2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Förändringar i personalvetarens arbete har gett upphov till spänningar mellan ekonomiska och humanistiska intressen, mellan arbetsgivare och arbetstagare, samt mellan den kompetens arbetsgivaren kräver och den befintliga kompetens personalvetarna besitter (Löfgren Martinsson, 2008, 12). Denna studie ämnar, genom intervjuer med personalvetare och HR-chefer, undersöka hur kraven på formell kompetens kommer till uttryck för personalvetare. Om dessa krav ligger i linje med vad yrkesverksamma personalvetare upplever är av vikt i det vardagliga arbetet samt om  utbildningen täcker in de efterfrågade kompetenserna som personalvetare samt HR-chefer upplever krävs i arbetet. Resultatet visar, att kraven på efterfrågad kompetens skiljer sig åt beroende på vilken nivå personalvetarna är verksamma. Efterfrågad kompetens på operativ nivå, såsom grundläggande kunskaper i beteendevetenskap och arbetsrätt, analytisk förmåga, samarbetsförmåga och kommunikativförmåga med flera, överensstämmer med den kompetens som yrkesverksamma personalvetare upplever är av vikt för arbetet på en operativ nivå. Dock ansågs inte dessa kompetenser tillräckliga för avancemang till högre positioner på strategisk nivå, då ytterligare kompetenser, som strategiskt tänkande, affärsmannaskap och finansiell kunskap upplevdes krävas för arbetet. Resultatet visar att respondenterna upplevde att utbildningen tillgodoser blivande personalvetare med kompetens för arbete på operativ nivå, men brister i att uttrusta studenterna med den kompetens som krävs för arbete på strategisk nivå.

  • 102045. Yasui, Takao
    et al.
    Ogawa, Kensuke
    Kaji, Noritada
    Nilsson, Mats
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Ajiri, Taiga
    Tokeshi, Manabu
    Horiike, Yasuhiro
    Baba, Yoshinobu
    Label-free detection of real-time DNA amplification using a nanofluidic diffraction grating2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 31642Article in journal (Refereed)
    Abstract [en]

    Quantitative DNA amplification using fluorescence labeling has played an important role in the recent, rapid progress of basic medical and molecular biological research. Here we report a label-free detection of real-time DNA amplification using a nanofluidic diffraction grating. Our detection system observed intensity changes during DNA amplification of diffracted light derived from the passage of a laser beam through nanochannels embedded in a microchannel. Numerical simulations revealed that the diffracted light intensity change in the nanofluidic diffraction grating was attributed to the change of refractive index. We showed the first case reported to date for label-free detection of real-time DNA amplification, such as specific DNA sequences from tubercle bacilli (TB) and human papillomavirus (HPV). Since our developed system allows quantification of the initial concentration of amplified DNA molecules ranging from 1 fM to 1 pM, we expect that it will offer a new strategy for developing fundamental techniques of medical applications.

  • 102046. Yatawatta, S.
    et al.
    de Bruyn, A. G.
    Brentjens, M. A.
    Labropoulos, P.
    Pandey, V. N.
    Kazemi, S.
    Zaroubi, S.
    Koopmans, L. V. E.
    Offringa, A. R.
    Jelic, V.
    Rubi, O. Martinez
    Veligatla, V.
    Wijnholds, S. J.
    Brouw, W. N.
    Bernardi, G.
    Ciardi, B.
    Daiboo, S.
    Harker, G.
    Mellema, Garrelt
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Schaye, J.
    Thomas, R.
    Vedantham, H.
    Chapman, E.
    Abdalla, F. B.
    Alexov, A.
    Anderson, J.
    Avruch, I. M.
    Batejat, F.
    Bell, M. E.
    Bell, M. R.
    Bentum, M.
    Best, P.
    Bonafede, A.
    Bregman, J.
    Breitling, F.
    van de Brink, R. H.
    Broderick, J. W.
    Brueggen, M.
    Conway, J.
    de Gasperin, F.
    de Geus, E.
    Duscha, S.
    Falcke, H.
    Fallows, R. A.
    Ferrari, C.
    Frieswijk, W.
    Garrett, M. A.
    Griessmeier, J. M.
    Gunst, A. W.
    Hassall, T. E.
    Hessels, J. W. T.
    Hoeft, M.
    Iacobelli, M.
    Juette, E.
    Karastergiou, A.
    Kondratiev, V. I.
    Kramer, M.
    Kuniyoshi, M.
    Kuper, G.
    van Leeuwen, J.
    Maat, P.
    Mann, G.
    McKean, J. P.
    Mevius, M.
    Mol, J. D.
    Munk, H.
    Nijboer, R.
    Noordam, J. E.
    Norden, M. J.
    Orru, E.
    Paas, H.
    Pandey-Pommier, M.
    Pizzo, R.
    Polatidis, A. G.
    Reich, W.
    Rottgering, H. J. A.
    Sluman, J.
    Smirnov, O.
    Stappers, B.
    Steinmetz, M.
    Tagger, M.
    Tang, Y.
    Tasse, C.
    ter Veen, S.
    Vermeulen, R.
    van Weeren, R. J.
    Wise, M.
    Wucknitz, O.
    Zarka, P.
    Initial deep LOFAR observations of epoch of reionization windows I. The north celestial pole2013In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 550, p. A136-Article in journal (Refereed)
    Abstract [en]

    Aims. The aim of the LOFAR epoch of reionization (EoR) project is to detect the spectral fluctuations of the redshifted HI 21 cm signal. This signal is weaker by several orders of magnitude than the astrophysical foreground signals and hence, in order to achieve this, very long integrations, accurate calibration for stations and ionosphere and reliable foreground removal are essential. Methods. One of the prospective observing windows for the LOFAR EoR project will be centered at the north celestial pole (NCP). We present results from observations of the NCP window using the LOFAR highband antenna (HBA) array in the frequency range 115 MHz to 163 MHz. The data were obtained in April 2011 during the commissioning phase of LOFAR. We used baselines up to about 30 km. The data was processed using a dedicated processing pipeline which is an enhanced version of the standard LOFAR processing pipeline. Results. With about 3 nights, of 6 h each, effective integration we have achieved a noise level of about 100 mu Jy/PSF in the NCP window. Close to the NCP, the noise level increases to about 180 mu Jy/PSF, mainly due to additional contamination from unsubtracted nearby sources. We estimate that in our best night, we have reached a noise level only a factor of 1.4 above the thermal limit set by the noise from our Galaxy and the receivers. Our continuum images are several times deeper than have been achieved previously using the WSRT and GMRT arrays. We derive an analytical explanation for the excess noise that we believe to be mainly due to sources at large angular separation from the NCP. We present some details of the data processing challenges and how we solved them. Conclusions. Although many LOFAR stations were, at the time of the observations, in a still poorly calibrated state we have seen no artefacts in our images which would prevent us from producing deeper images in much longer integrations on the NCP window which are about to commence. The limitations present in our current results are mainly due to sidelobe noise from the large number of distant sources, as well as errors related to station beam variations and rapid ionospheric phase fluctuations acting on bright sources. We are confident that we can improve our results with refined processing.

  • 102047. Yates, TJV
    et al.
    Thomas, JM
    Fernandez, JJ
    Terasaki, O
    Stockholm University.
    Ryoo, R
    Midgley, PA
    Three-dimensional real-space crystallography of MCM-48 mesoporous silica revealed by scanning transmission electron tomography2006In: Chemical Physics Letters, Vol. 418, p. 540-543Article in journal (Refereed)
  • 102048. Yatsyna, Vasyl
    et al.
    Bakker, Daniel J.
    Salén, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Feifel, Raimund
    Rijs, Anouk M.
    Zhaunerchyk, Vitali
    Infrared Action Spectroscopy of Low-Temperature Neutral Gas-Phase Molecules of Arbitrary Structure2016In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 117, no 11, article id 118101Article in journal (Refereed)
    Abstract [en]

    We demonstrate a technique for IR action spectroscopy that enables measuring IR spectra in a background-free fashion for low-temperature neutral gas-phase molecules of arbitrary structure. The method is exemplified experimentally for N-methylacetamide molecules in the mid-IR spectral range of 1000-1800 cm(-1), utilizing the free electron laser FELIX. The technique involves the resonant absorption of multiple mid-IR photons, which induces molecular dissociation. The dissociation products are probed with 10.49 eV vacuum ultraviolet photons and analyzed with a mass spectrometer. We also demonstrate the capability of this method to record, with unprecedented ease, mid-IR spectra for the molecular associates, such as clusters and oligomers, present in a molecular beam. In this way the mass-selected spectra of low-temperature gas-phase dimers and trimers of N-methylacetamide are measured in the full amide I-III range.

  • 102049.
    Yau, Kayan
    Stockholm University, Faculty of Social Sciences, School of Business.
    Clas Ohlsons etablering i Norge: En fallstudie ur ett situationsanpassningsperpektiv2006Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    ”When in Rome, do as Romans do”. Detta ordspråk myntades 387 e. Kr av St. Ambrose när han uttryckte ”när jag är i Rom fastar jag på lördagar; när jag är i Milano, gör jag inte det”. Efter hand kom det att innebära, ta seden dit du kommer. Detta gamla talesätt kan även tillämpas när inhemska företag utvidgar deras verksamhet utanför de nationella gränserna, där den naturliga strategin enligt St. Ambrose skulle vara en anpassning till de nya förhållandena som uppstår på en ny marknad. Anpassning kan dock komma i konflikt med de visioner, mål och strategier som företagen upprättat på hemmamarknaden. En alternativ situationanpassningsstrategi är standardisering. Syftet med denna studie är att analysera hur företag agerar vid etablering på en ny marknad. Vidare avser studien att undersöka hur och om företag tenderar att anpassa sina visioner, mål och strategier vid etablering utomlands. För att uppnå detta syfte har författaren genomfört en kvalitativ fallstudie med Clas Ohlson AB i fokus. Situationsanpassningsteorier och strategier var utgångspunkten i denna studie, vilket karaktäriserar ett deduktivt tillvägagångssätt. Intervjuer med Clas Ohlsons VD för dotterbolaget i Norge samt etableringschefen vid huvudkontoret i Insjön har genomförts för att insamla relevant information i avsikt att besvara studiens syfte. En övergripande slutsats författaren kom fram till var att en situationsanpassning inte var nödvändig i Clas Ohlsons fall. Det kan ifrågasättas huruvida Clas Ohlson endast har turen med sig eller om deras expansion i hög grad varit välplanerad. Många faktorer indikerar att det senare alternativet är det riktiga.

  • 102050.
    Yazdanfar, Darush
    Stockholm University, Faculty of Social Sciences, Stockholm Business School.
    Futures som ett mångsidigt instrument: En empirisk studie av oljebolag som använder futureskontrakt2004Doctoral thesis, monograph (Other academic)
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