79 research outputs found

    Collapse of the vortex-lattice inductance and shear modulus at the melting transition in untwinned YBa2Cu3O7\rm YBa_2Cu_3O_7

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    The complex resistivity ρ^(ω)\hat{\rho}(\omega) of the vortex lattice in an untwinned crystal of 93-K YBa2Cu3O7\rm YBa_2Cu_3O_7 has been measured at frequencies ω/2π\omega/2\pi from 100 kHz to 20 MHz in a 2-Tesla field H∥c\bf H\parallel c, using a 4-probe RF transmission technique that enables continuous measurements versus ω\omega and temperature TT. As TT is increased, the inductance Ls(ω)=Imρ^(ω)/ω{\cal L}_s(\omega) ={\rm Im} \hat{\rho}(\omega)/ \omega increases steeply to a cusp at the melting temperature TmT_m, and then undergoes a steep collapse consistent with vanishing of the shear modulus c66c_{66}. We discuss in detail the separation of the vortex-lattice inductance from the `volume' inductance, and other skin-depth effects. To analyze the spectra, we consider a weakly disordered lattice with a low pin density. Close fits are obtained to ρ1(ω)\rho_1(\omega) over 2 decades in ω\omega. Values of the pinning parameter κ\kappa and shear modulus c66c_{66} obtained show that c66c_{66} collapses by over 4 decades at TmT_m, whereas κ\kappa remains finite.Comment: 11 pages, 8 figures, Phys. Rev. B, in pres

    The Entanglement in Anisotropic Heisenberg XYZ Chain with inhomogeneous magnetic field

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    The thermal entanglement of a two-qubit anisotropic Heisenberg XYZXYZ chain under an inhomogeneous magnetic field b is studied. It is shown that when inhomogeneity is increased to certain value, the entanglement can exhibit a larger revival than that of less values of b. The property is both true for zero temperature and a finite temperature. The results also show that the entanglement and critical temperature can be increased by increasing inhomogeneous exteral magnetic field

    Clinical and Imaging Features of Leukemic Retinopathy

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    Hematological malignancies may be associated with ocular manifestations in up to 50% of cases, and ocular symptoms can be the initial presentation. Retinal leukemic infiltrates may be observed in up to 3% of leukemia patients. Leukemic retinopathy may present more commonly in acute leukemias than chronic leukemias as Roth’s spot, multi-level retinal hemorrhages, cotton wool spots, or opportunistic infection secondary to pancytopenia. On the other hand, patients with chronic leukemias, such as chronic myeloid leukemia (CML), may present with leukemic retinal infiltrates and venous stasis secondary to hyperviscosity, which may lead to secondary peripheral microaneurysms and neovascularization. Vascular complication, such as central retinal vein occlusion, may also occur as a result of venous stasis. In addition, leukemic retinopathy is associated with poorer overall survival as pediatric CML patients without ocular manifestation may have twice as high 5-years survival rate compared with those with ocular manifestation. The presence of leukemic retinopathy is associated with more severe systemic disease and is correlated with hematological parameters such as white blood cells count (WBC). In addition, a positive correlation was found between ocular leukemic infiltration and agonal leukocyte count and the severity of systemic disease in an autopsy study. Therefore, the presence of retinal infiltrate may be associated with leukemia with extreme leukocytosis. Optical Coherence Tomography (OCT) is a noninvasive retinal imaging tool that can help diagnose leukemic retinopathy. Inner retina hyper-reflective lesions were observed in areas with intra-retinal hemorrhages or hemorrhagic lesions, while outer retina hyper-reflective lesions were observed in areas with whitish retinal infiltrates. In addition, the loss of the physiological hourglass appearance on cross-sectional OCT scan of retinal vessels may be seen in leukemic retinopathy. It is believed that intraluminal blood flow is responsible for the physiological hourglass appearance, consisting of two paired hyper-reflectivities inside vessel wall on OCT. In leukemic retinopathy, hyperviscosity may disrupt normal intraluminal blood flow, leading to the loss of this physiological appearance. In summary, leukemic retinopathy can be the first presentation of leukemia. Ophthalmologists can play an important role in the diagnosis of leukemia. Noninvasive retinal imaging could help us to monitor and understand the pathophysiology of leukemic retinal infiltrates. Prompt diagnosis and treatment of underlying leukemia may preserve vision and prolong survival rate

    Perception and evaluation of 23 positive emotions in Hong Kong and the Netherlands

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    Positive emotions are linked to numerous benefits, but not everyone appreciates the same kinds of positive emotional experiences. We examine how distinct positive emotions are perceived and whether individuals’ perceptions are linked to how societies evaluate those emotions. Participants from Hong Kong and Netherlands rated 23 positive emotions based on their individual perceptions (positivity, arousal, and socially engaging) and societal evaluations (appropriate, valued, and approved of). We found that (1) there were cultural differences in judgments about all six aspects of positive emotions; (2) positivity, arousal, and social engagement predicted emotions being positively regarded at the societal level in both cultures; and (3) that positivity mattered more for the Dutch participants, although arousal and social engagement mattered more in Hong Kong for societal evaluations. These findings provide a granular map of the perception and evaluation of distinct positive emotions in two cultures and highlight the role of cultures in the understanding how positive emotions are perceived and evaluated

    Education in IT Security: A Case Study in Banking Industry

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    The banking industry has been changing incessantlyand facing new combination of risks. Data protection andcorporate security is now one of the major issues in bankingindustry. As the rapid changing on technologies from time totime, the industry should be aware on new technologies in orderto protect information assets and prevent fraud activities. Thispaper begins with literature study of information security issuesand followed by focused-group interviews with five participantswithin the industry and survey analysis of “The global state ofInformation Security survey 2013” which published byPriceWaterhouseCoopers (PWC). Trends and questions werediscussed as well as possible solution. The study suggests that ITsecurity education should be made to different level of staffs suchas executives, professional and general staffs. Besides, thebanking industry should increase company-wide securityawareness and the importance of corporate security which keepthe information and physical assets secure and in a proper way

    Quantum Correlation in One-dimensional Extend Quantum Compass Model

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    We study the correlations in the one-dimensional extended quantum compass model in a transverse magnetic field. By exactly solving the Hamiltonian, we find that the quantum correlation of the ground state of one-dimensional quantum compass model is vanishing. We show that quantum discord can not only locate the quantum critical points, but also discern the orders of phase transitions. Furthermore, entanglement quantified by concurrence is also compared.Comment: 8 pages, 14 figures, to appear in Eur. Phys. J.

    Cosmological parameters from SDSS and WMAP

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    We measure cosmological parameters using the three-dimensional power spectrum P(k) from over 200,000 galaxies in the Sloan Digital Sky Survey (SDSS) in combination with WMAP and other data. Our results are consistent with a ``vanilla'' flat adiabatic Lambda-CDM model without tilt (n=1), running tilt, tensor modes or massive neutrinos. Adding SDSS information more than halves the WMAP-only error bars on some parameters, tightening 1 sigma constraints on the Hubble parameter from h~0.74+0.18-0.07 to h~0.70+0.04-0.03, on the matter density from Omega_m~0.25+/-0.10 to Omega_m~0.30+/-0.04 (1 sigma) and on neutrino masses from <11 eV to <0.6 eV (95%). SDSS helps even more when dropping prior assumptions about curvature, neutrinos, tensor modes and the equation of state. Our results are in substantial agreement with the joint analysis of WMAP and the 2dF Galaxy Redshift Survey, which is an impressive consistency check with independent redshift survey data and analysis techniques. In this paper, we place particular emphasis on clarifying the physical origin of the constraints, i.e., what we do and do not know when using different data sets and prior assumptions. For instance, dropping the assumption that space is perfectly flat, the WMAP-only constraint on the measured age of the Universe tightens from t0~16.3+2.3-1.8 Gyr to t0~14.1+1.0-0.9 Gyr by adding SDSS and SN Ia data. Including tensors, running tilt, neutrino mass and equation of state in the list of free parameters, many constraints are still quite weak, but future cosmological measurements from SDSS and other sources should allow these to be substantially tightened.Comment: Minor revisions to match accepted PRD version. SDSS data and ppt figures available at http://www.hep.upenn.edu/~max/sdsspars.htm

    Large expert-curated database for benchmarking document similarity detection in biomedical literature search

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    Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe
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