9,373 research outputs found

    Cell biology:Collagen secretion explained

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    Cells package proteins into vesicles for secretion to the extracellular milieu. A study shows that an enzyme modifies the packaging machinery to encapsulate unusually large proteins such as collagen

    Plasmonic colloidal nanoparticles with open eccentric cavities via acid-induced chemical transformation

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    Surface-enhanced Raman spectroscopy (SERS) has been considered a promising technique for the detection of trace molecules in biomedicine and environmental monitoring. The ideal metal nanoparticles for SERS must not only fulfill important requirements such as high near-field enhancement and a tunable far-field response but also overcome the diffusion limitation at extremely lower concentrations of a target material. Here, we introduce a novel method to produce gold nanoparticles with open eccentric cavities by selectively adapting the structure of non-plasmonic nanoparticles via acid-mediated surface replacement. Copper oxide nanoparticles with open eccentric cavities are first prepared using a microwave-irradiation-assisted surfactant-free hydrothermal reaction and are then transformed into gold nanoparticles by an acidic gold precursor while maintaining their original structure. Because of the strong near-field enhancement occurring at the mouth of the open cavities and the very rough surfaces resulting from the uniformly covered hyperbranched sharp multi-tips and the free access of SERS molecules inside of the nanoparticles without diffusion limitation, adenine, one of the four bases in DNA, in an extremely diluted aqueous solution (1.0 pM) was successfully detected with excellent reproducibility upon laser excitation with a 785-nm wavelength. The gold nanoparticles with open eccentric cavities provide a powerful platform for the detection of ultra-trace analytes in an aqueous solution within near-infrared wavelengths, which is essential for highly sensitive, reliable and direct in vivo analysis.None1132sciescopu

    A compact statistical model of the song syntax in Bengalese finch

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    Songs of many songbird species consist of variable sequences of a finite number of syllables. A common approach for characterizing the syntax of these complex syllable sequences is to use transition probabilities between the syllables. This is equivalent to the Markov model, in which each syllable is associated with one state, and the transition probabilities between the states do not depend on the state transition history. Here we analyze the song syntax in a Bengalese finch. We show that the Markov model fails to capture the statistical properties of the syllable sequences. Instead, a state transition model that accurately describes the statistics of the syllable sequences includes adaptation of the self-transition probabilities when states are repeatedly revisited, and allows associations of more than one state to the same syllable. Such a model does not increase the model complexity significantly. Mathematically, the model is a partially observable Markov model with adaptation (POMMA). The success of the POMMA supports the branching chain network hypothesis of how syntax is controlled within the premotor song nucleus HVC, and suggests that adaptation and many-to-one mapping from neural substrates to syllables are important features of the neural control of complex song syntax

    Study of psi(2S) decays to X J/psi

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    Using J/psi -> mu^+ mu^- decays from a sample of approximately 4 million psi(2S) events collected with the BESI detector, the branching fractions of psi(2S) -> eta J/psi, pi^0 pi^0 J/psi, and anything J/psi normalized to that of psi(2S) -> pi^+ pi^- J/psi are measured. The results are B(psi(2S) -> eta J/psi)/B(psi(2S) -> pi^+ pi^- J/psi) = 0.098 \pm 0.005 \pm 0.010, B(psi(2S) -> pi^0 pi^0 J/psi)/B(psi(2S) -> pi^+ pi^- J/psi) = 0.570 \pm 0.009 \pm 0.026, and B(psi(2S) -> anything J/psi)/B(psi(2S) -> pi^+ pi^- J/psi) = 1.867 \pm 0.026 \pm 0.055.Comment: 13 pages, 8 figure

    Anticoagulation Control in Warfarin-Treated Patients Undergoing Cardioversion of Atrial Fibrillation (from the Edoxaban Versus Enoxaparin-Warfarin in Patients Undergoing Cardioversion of Atrial Fibrillation Trial).

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    In the Edoxaban Versus Enoxaparin-Warfarin in Patients Undergoing Cardioversion of Atrial Fibrillation (ENSURE-AF) study (NCT 02072434), edoxaban was compared with enoxaparin-warfarin in 2,199 patients undergoing electrical cardioversion of nonvalvular atrial fibrillation (AF). In this multicenter prospective randomized open blinded end-point trial, we analyzed patients randomized to enoxaparin-warfarin. We determined time to achieve therapeutic range (TtTR); time in therapeutic range (TiTR); their clinical determinants; relation to sex, age, medical history, treatment, tobacco use, race risk (SAMe-TT2R2) score; and impact on primary end points (composite of stroke, systemic embolic event[SEE], myocardial infarction [MI], and cardiovascular death [CVD] and composite of major + clinically relevant nonmajor bleeding). Among 1,104 patients randomized to enoxaparin-warfarin, 27% were naïve to oral anticoagulants. Mean age was 64.2 ± 11 years and mean congestive heart failure, hypertension, age ≥75 (doubled), diabetes mellitus, prior stroke or transient ischemic attack (doubled), vascular disease, age 65-74, female (CHA2DS2-VASc) score was 2.6. Mean TtTR was 7.7 days (median 7 days) and mean TiTR after reaching an international normalized ratio of 2.0 to 3.0 was 71%. In 695 patients who had an INR 2. On multivariate regression, an independent predictor of extended TtTR was creatinine clearance (p = 0.02). TtTR was marginally related to stroke/SEE/MI/CVD (p = 0.06; odds ratio  0.23, 95% confidence interval 0.02 to 1.17) but not to any bleeding. Independent predictors of TiTR were previous vitamin K antagonist experience (p65, concomitant drugs or alcohol (HAS-BLED) score (p = 0.02). TiTR was related to any bleeding (p = 0.02; odds ratio  0.39, 95% confidence interval 0.16 to 0.88), but not stroke/SEE/MI/CVD. In this cohort of warfarin users with a high TiTR no difference was seen between TtTR and TiTR in relation to SAMe-TT2R2 score. In conclusion, even in this short-term study, TiTR was significantly related to bleeding events

    The clock genes Period 2 and Cryptochrome 2 differentially balance bone formation

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    Background: Clock genes and their protein products regulate circadian rhythms in mammals but have also been implicated in various physiological processes, including bone formation. Osteoblasts build new mineralized bone whereas osteoclasts degrade it thereby balancing bone formation. To evaluate the contribution of clock components in this process, we investigated mice mutant in clock genes for a bone volume phenotype. Methodology/Principal Findings: We found that Per2Brdm1 mutant mice as well as mice lacking Cry2-/- displayed significantly increased bone volume at 12 weeks of age, when bone turnover is high. Per2Brdm1 mutant mice showed alterations in parameters specific for osteoblasts whereas mice lacking Cry2-/- displayed changes in osteoclast specific parameters. Interestingly, inactivation of both Per2 and Cry2 genes leads to normal bone volume as observed in wild type animals. Importantly, osteoclast parameters affected due to the lack of Cry2, remained at the level seen in the Cry2-/- mutants despite the simultaneous inactivation of Per2. Conclusions/Significance: This indicates that Cry2 and Per2 affect distinct pathways in the regulation of bone volume with Cry2 influencing mostly the osteoclastic cellular component of bone and Per2 acting on osteoblast parameters

    Uncertainty quantification for kinetic models in socio-economic and life sciences

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    Kinetic equations play a major rule in modeling large systems of interacting particles. Recently the legacy of classical kinetic theory found novel applications in socio-economic and life sciences, where processes characterized by large groups of agents exhibit spontaneous emergence of social structures. Well-known examples are the formation of clusters in opinion dynamics, the appearance of inequalities in wealth distributions, flocking and milling behaviors in swarming models, synchronization phenomena in biological systems and lane formation in pedestrian traffic. The construction of kinetic models describing the above processes, however, has to face the difficulty of the lack of fundamental principles since physical forces are replaced by empirical social forces. These empirical forces are typically constructed with the aim to reproduce qualitatively the observed system behaviors, like the emergence of social structures, and are at best known in terms of statistical information of the modeling parameters. For this reason the presence of random inputs characterizing the parameters uncertainty should be considered as an essential feature in the modeling process. In this survey we introduce several examples of such kinetic models, that are mathematically described by nonlinear Vlasov and Fokker--Planck equations, and present different numerical approaches for uncertainty quantification which preserve the main features of the kinetic solution.Comment: To appear in "Uncertainty Quantification for Hyperbolic and Kinetic Equations
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