3,420 research outputs found

    Dynamical Scaling Behavior of Percolation Clusters in Scale-free Networks

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    In this work we investigate the spectra of Laplacian matrices that determine many dynamic properties of scale-free networks below and at the percolation threshold. We use a replica formalism to develop analytically, based on an integral equation, a systematic way to determine the ensemble averaged eigenvalue spectrum for a general type of tree-like networks. Close to the percolation threshold we find characteristic scaling functions for the density of states rho(lambda) of scale-free networks. rho(lambda) shows characteristic power laws rho(lambda) ~ lambda^alpha_1 or rho(lambda) ~ lambda^alpha_2 for small lambda, where alpha_1 holds below and alpha_2 at the percolation threshold. In the range where the spectra are accessible from a numerical diagonalization procedure the two methods lead to very similar results.Comment: 9 pages, 6 figure

    Reuse of design pattern measurements for health data

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    Research using health data is challenged by its heterogeneous nature, description and storage. The COVID-19 outbreak made clear that rapid analysis of observations such as clinical measurements across a large number of healthcare providers can have enormous health benefits. This has brought into focus the need for a common model of quantitative health data that enables data exchange and federated computational analysis. The application of ontologies, Semantic Web technologies and the FAIR principles is an approach used by different life science research projects, such as the European Joint Programme on Rare Diseases, to make data and metadata machine readable and thereby reduce the barriers for data sharing and analytics and harness health data for discovery. Here, we show the reuse of a pattern for measurements to model diverse health data, to demonstrate and raise visibility of the usefulness of this pattern for biomedical research

    One-body dissipation and chaotic dynamics in a classical simulation of a nuclear gas

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    In order to understand the origin of one-body dissipation in nuclei, we analyze the behavior of a gas of classical particles moving in a two-dimensional cavity with nuclear dimensions. This "nuclear" billiard has multipole-deformed walls which undergo periodic shape oscillations. We demonstrate that a single particle Hamiltonian containing coupling terms between the particles' motion and the collective coordinate induces a chaotic dynamics for any multipolarity, independently on the geometry of the billiard. If the coupling terms are switched off the "wall formula" predictions are recovered. We discuss the dissipative behavior of the wall motion and its relation with the order-to-chaos transition in the dynamics of the microscopic degrees of freedom.Comment: 16 pages, 12 postscript figures included, revtex, new version completely revised accepted by Physical Review C and scheduled to appear in the issue of november 199

    Child-Abuse-Related-Deaths, Child Mortality (0-4) & Income Inequality in America and Other Developed Nations 1989-91 v 2012-14: Speaking Truth to Power.

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    The major concern for social work, namely child abuse‐related deaths (CARD), involves parental neglect. Societal neglect, when measured by child mortality rates (CMR), is considered by bodies such as UNICEF to be indicative of how a nation meets the needs of its children. This population‐based study analyses CARD and CMR for children aged from newborn to four years old between 1989–91 and 2013–15 to identify any relative child neglect in the USA and 20 other developed nations (ODN). World Health Organization data were used for CARD, CMR and undetermined deaths (UnD), a possible source of unreported CARD, juxtaposed against World Bank income inequality data. The USA had the highest number of CARD, the highest CMR and the worst income inequality. Five countries reduced their CARD significantly more than the USA, and 14 countries reduced their CMR more than the USA. Income inequality and CMR were correlated. Had the USA matched the CMR of Japan, where income inequality was narrowest, there would have been on average 16 745 fewer child deaths annually. CARD and UnD correlated, suggesting that UnD may contain unreported CARD. US CMR data indicate that services in the USA are less effective than those in ODN, possibly due to income inequality. These results will be unwelcome but child protection services must dare to speak truth to power. ‘This population‐based study analyses CARD and CMR for children aged from newborn to four years old between 1989–91 and 2013–15 to identify any relative child neglect in the USA and 20 other developed nations’ Key Practitioner Messages The richest country in the world, the USA, has the highest rates of child abuse and total child mortality in the Western world. The USA has the highest income inequality in the West, highlighting the statistical link between child mortality and poverty. Children's services should lead the call for the necessary changes and ‘speak truth to power’

    Bethe ansatz for the Harper equation: Solution for a small commensurability parameter

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    The Harper equation describes an electron on a 2D lattice in magnetic field and a particle on a 1D lattice in a periodic potential, in general, incommensurate with the lattice potential. We find the distribution of the roots of Bethe ansatz equations associated with the Harper equation in the limit as alpha=1/Q tends to 0, where alpha is the commensurability parameter (Q is integer). Using the knowledge of this distribution we calculate the higher and lower boundaries of the spectrum of the Harper equation for small alpha. The result is in agreement with the semiclassical argument, which can be used for small alpha.Comment: 17 pages including 5 postscript figures, Latex, minor changes, to appear in Phys.Rev.

    Large Orbital Magnetic Moment and Coulomb Correlation effects in FeBr2

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    We have performed an all-electron fully relativistic density functional calculation to study the magnetic properties of FeBr2. We show for the first time that the correlation effect enhances the contribution from orbital degrees of freedom of dd electrons to the total magnetic moment on Fe2+^{2+} as opposed to common notion of nearly total quenching of the orbital moment on Fe2+^{2+} site. The insulating nature of the system is correctly predicted when the Hubbard parameter U is included. Energy bands around the gap are very narrow in width and originate from the localized Fe-3dd orbitals, which indicates that FeBr2 is a typical example of the Mott insulator.Comment: 4 pages, 3 figures, revtex4, PRB accepte

    Comprehensive plasma proteomic profiling reveals biomarkers for active tuberculosis

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    BACKGROUND. Tuberculosis (TB) kills more people than any other infection, and new diagnostic tests to identify active cases are required. We aimed to discover and verify novel markers for TB in nondepleted plasma. / METHODS. We applied an optimized quantitative proteomics discovery methodology based on multidimensional and orthogonal liquid chromatographic separation combined with high-resolution mass spectrometry to study nondepleted plasma of 11 patients with active TB compared with 10 healthy controls. Prioritized candidates were verified in independent UK (n = 118) and South African cohorts (n = 203). / RESULTS. We generated the most comprehensive TB plasma proteome to date, profiling 5022 proteins spanning 11 orders-of-magnitude concentration range with diverse biochemical and molecular properties. We analyzed the predominantly low–molecular weight subproteome, identifying 46 proteins with significantly increased and 90 with decreased abundance (peptide FDR ≀ 1%, q ≀ 0.05). Verification was performed for novel candidate biomarkers (CFHR5, ILF2) in 2 independent cohorts. Receiver operating characteristics analyses using a 5-protein panel (CFHR5, LRG1, CRP, LBP, and SAA1) exhibited discriminatory power in distinguishing TB from other respiratory diseases (AUC = 0.81). / CONCLUSION. We report the most comprehensive TB plasma proteome to date, identifying novel markers with verification in 2 independent cohorts, leading to a 5-protein biosignature with potential to improve TB diagnosis. With further development, these biomarkers have potential as a diagnostic triage test. / FUNDING. Colciencias, Medical Research Council, Innovate UK, NIHR, Academy of Medical Sciences, Program for Advanced Research Capacities for AIDS, Wellcome Centre for Infectious Diseases Research

    Wavepacket reconstruction via local dynamics in a parabolic lattice

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    We study the dynamics of a wavepacket in a potential formed by the sum of a periodic lattice and of a parabolic potential. The dynamics of the wavepacket is essentially a superposition of ``local Bloch oscillations'', whose frequency is proportional to the local slope of the parabolic potential. We show that the amplitude and the phase of the Fourier transform of a signal characterizing this dynamics contains information about the amplitude and the phase of the wavepacket at a given lattice site. Hence, {\em complete} reconstruction of the the wavepacket in the real space can be performed from the study of the dynamics of the system.Comment: 4 pages, 3 figures, RevTex

    Tracking Holocene palaeostratification and productivity changes in the Western Irish Sea: A multi-proxy record

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.The Western Irish Sea preserves an exceptionally thick (ca. 40 m) Holocene succession that is ideally suited to understanding the pattern of palaeostratification and water mass productivity changes in the region, and their relationship with sea level, sedimentation, and biota. Additionally, the presence of shallow-buried methane provides an opportunity to explore its potential impact on the local pattern of Holocene marine environmental change. Multi-proxy investigation of a cored borehole succession through the Holocene interval tracks changes from mixed to seasonally stratified conditions. In the earliest Holocene (11.2–10 ka), high productivity, mixed water conditions prevailed, with abundant and diverse foraminifera and dominant heterotrophic dinoflagellate cysts. Productivity was probably driven by high nutrient fluxes related to high rates of sedimentation (>1600 cm/kyr), in turn influenced by relatively low sea level and restricted sediment accommodation space across shelf areas to the east of the borehole site (eastern Irish Sea Basin). With rising sea level in the later part of the Early Holocene, the region evolved into a relatively lower productivity mixed water mass system, with significant changes in ecology revealed by dinoflagellate cysts and foraminifera. In the latest Early Holocene and earliest Mid Holocene (ca. 8.4–8.2 ka) a return to higher productivity is signalled by dinoflagellate cyst data; a result of seasonal stratification becoming established, evidenced by sharply increased summer sea surface temperature estimates (typically 16–17 °C) that contrast with an opposite (more positive) trend in ή18O values for benthic foraminifera. Reductions in turbulent mixing associated with stratification might have exacerbated the palaeoecological impact of shallow-buried methane associated with the borehole site, potentially evidenced by a significant change in dominant benthic foraminifera and strong, localised excursions in the benthic ή13C/ή18O record

    The Trypanosoma cruzi vitamin C dependent peroxidase confers protection against oxidative stress but is not a determinant of virulence.

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    BACKGROUND: The neglected parasitic infection Chagas disease is rapidly becoming a globalised public health issue due to migration. There are only two anti-parasitic drugs available to treat this disease, benznidazole and nifurtimox. Thus it is important to identify and validate new drug targets in Trypanosoma cruzi, the causative agent. T. cruzi expresses an ER-localised ascorbate-dependent peroxidase (TcAPx). This parasite-specific enzyme has attracted interest from the perspective of targeted chemotherapy. METHODOLOGY/PRINCIPAL FINDINGS: To assess the importance of TcAPx in protecting T. cruzi from oxidative stress and to determine if it is essential for virulence, we generated null mutants by targeted gene disruption. Loss of activity was associated with increased sensitivity to exogenous hydrogen peroxide, but had no effect on susceptibility to the front-line Chagas disease drug benznidazole. This suggests that increased oxidative stress in the ER does not play a significant role in its mechanism of action. Homozygous knockouts could proceed through the entire life-cycle in vitro, although they exhibited a significant decrease in their ability to infect mammalian cells. To investigate virulence, we exploited a highly sensitive bioluminescence imaging system which allows parasites to be monitored in real-time in the chronic stage of murine infections. This showed that depletion of enzyme activity had no effect on T. cruzi replication, dissemination or tissue tropism in vivo. CONCLUSIONS/SIGNIFICANCE: TcAPx is not essential for parasite viability within the mammalian host, does not have a significant role in establishment or maintenance of chronic infections, and should therefore not be considered a priority for drug design
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