860 research outputs found

    Balanced data assimilation for highly-oscillatory mechanical systems

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    Data assimilation algorithms are used to estimate the states of a dynamical system using partial and noisy observations. The ensemble Kalman filter has become a popular data assimilation scheme due to its simplicity and robustness for a wide range of application areas. Nevertheless, the ensemble Kalman filter also has limitations due to its inherent Gaussian and linearity assumptions. These limitations can manifest themselves in dynamically inconsistent state estimates. We investigate this issue in this paper for highly oscillatory Hamiltonian systems with a dynamical behavior which satisfies certain balance relations. We first demonstrate that the standard ensemble Kalman filter can lead to estimates which do not satisfy those balance relations, ultimately leading to filter divergence. We also propose two remedies for this phenomenon in terms of blended time-stepping schemes and ensemble-based penalty methods. The effect of these modifications to the standard ensemble Kalman filter are discussed and demonstrated numerically for two model scenarios. First, we consider balanced motion for highly oscillatory Hamiltonian systems and, second, we investigate thermally embedded highly oscillatory Hamiltonian systems. The first scenario is relevant for applications from meteorology while the second scenario is relevant for applications of data assimilation to molecular dynamics

    Photosynthetic Capacity within the Phantom Gas Field Project

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    Anthropogenic noise has proven detrimental to organisms like bats, owls, and certain other species whose hunting or navigation success is affected by unnatural sound. However, few studies have quantified the effects of noise pollution across multiple trophic levels. Our study is quantifying the impacts of human noise on insect abundance and herbivory, and plant physiology, using experimental noise stations compared to quiet control sites in the sagebrush steppe southwest of Boise, Idaho. I am measuring variation in leaf chlorophyll fluorescence and Normalized Difference Vegetation Index (NDVI). Both of these measurements are indirect measurements of photosynthetic capacity. We hypothesized that shrubs in “noise ON” sites will have increased insect abundance and herbivory (leaf damage), and thus declines in photosynthetic capacity, due to decreased predation on insects by birds and bats at these sites. Preliminary data suggest that photosynthetic capacity is slightly less at noise ON sites compared to control sites

    Quantum Dynamics of Solitons in Strongly Interacting Systems on Optical Lattices

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    Mean-field dynamics of strongly interacting bosons described by hard core bosons with nearest-neighbor attraction has been shown to support two species of solitons: one of Gross-Pitaevskii (GP-type) where the condensate fraction remains dark and a novel non-Gross-Pitaevskii-type (non-GP-type) characterized by brightening of the condensate fraction. Here we study the effects of quantum fluctuations on these solitons using the adaptive time-dependent density matrix renormalization group method, which takes into account the effect of strong correlations. We use local observables as the density, condensate density and correlation functions as well as the entanglement entropy to characterize the stability of the initial states. We find both species of solitons to be stable under quantum evolution for a finite duration, their tolerance to quantum fluctuations being enhanced as the width of the soliton increases. We describe possible experimental realizations in atomic Bose Einstein Condensates, polarized degenerate Fermi gases, and in systems of polar molecules on optical lattices

    Increased Volume and Function of Right Auditory Cortex as a Marker for Absolute Pitch

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    Absolute pitch (AP) perception is the auditory ability to effortlessly recognize the pitch of any given tone without external reference. To study the neural substrates of this rare phenomenon, we developed a novel behavioral test, which excludes memory-based interval recognition and permits quantification of AP proficiency independently of relative pitch cues. AP- and non-AP-possessing musicians were studied with morphological and functional magnetic resonance imaging (fMRI) and magnetoencephalography. Gray matter volume of the right Heschl's gyrus (HG) was highly correlated with AP proficiency. Right-hemispheric auditory evoked fields were increased in the AP group. fMRI revealed an AP-dependent network of right planum temporale, secondary somatosensory, and premotor cortices, as well as left-hemispheric "Broca's” area. We propose the right HG as an anatomical marker of AP and suggest that a right-hemispheric network mediates AP "perception,” whereas pitch "labeling” takes place in the left hemispher

    A concise revised myeloma comorbidity index as a valid prognostic instrument in a large cohort of 801 multiple myeloma patients

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    With growing numbers of elderly multiple myeloma patients, reliable tools to assess their vulnerability are required. The objective of the analysis herein was to develop and validate an easy to use myeloma risk score (revised Myeloma Comorbidity Index) that allows for risk prediction of overall survival and progression-free survival differences in a large patient cohort. We conducted a comprehensive comorbidity, frailty and disability evaluation in 801 consecutive myeloma patients, including comorbidity risks obtained at diagnosis. The cohort was examined within a training and validation set. Multivariate analysis determined renal, lung and Karnofsky Performance Status impairment, frailty and age as significant risks for overall survival. These were combined in a weighted revised Myeloma Comorbidity Index, allowing for the identification of fit (revised Myeloma Comorbidity Index ≤3 [n=247, 30.8%]), intermediate-fit (revised Myeloma Comorbidity Index 4-6 [n=446, 55.7%]) and frail patients (revised Myeloma Comorbidity Index >6 [n=108, 13.5%]): these subgroups, confirmed via validation analysis, showed median overall survival rates of 10.1, 4.4 and 1.2 years, respectively. The revised Myeloma Comorbidity Index was compared to other commonly used comorbidity indices (Charlson Comorbidity Index, Hematopoietic Cell Transplantation-Specific Comorbidity Index, Kaplan-Feinstein Index): if each were divided in risk groups based on 25% and 75% quartiles, highest hazard ratios, best prediction and Brier scores were achieved with the revised Myeloma Comorbidity Index. The advantages of the revised Myeloma Comorbidity Index include its accurate assessment of patients' physical conditions and simple clinical applicability. We propose the revised Myeloma Comorbidity Index to be tested with the “reference” International Myeloma Working Group frailty score in multicenter analyses and future clinical trials

    Liga de enfermagem em urgência e emergência: espaço acadêmico de educação em saúde à comunidade

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    Anais do 35º Seminário de Extensão Universitária da Região Sul - Área temática: SaúdeIntrodução: A educação em saúde pode ser concretizada de diversas formas e em múltiplos contextos, na área da saúde, e mais especificamente na área da urgência e emergência, o presente projeto de extensão tem buscado a educação em saúde como forma de capacitar a comunidade para reconhecer uma emergência e realizar seus primeiros atendimentos de maneira segura. Oferecer capacitações para a comunidade é uma forma efetiva de aumentar a sobrevida em casos de emergência. Acidentes podem apresentar-se a qualquer momento e em qualquer ambiente da vida cotidiana, a partir desse fato emergiu a ideia de proporcionar à comunidade capacitações sobre primeiros socorros, visando contribuir para o reconhecimento e para as tomadas de atitudes frente aos agravos de saúde que necessitem de ação rápida e efetiva. Objetivo: Inserir acadêmicos de graduação e de pós-graduação em Enfermagem no planejamento e desenvolvimento de ações voltadas à prevenção de acidentes domésticos e à educação para urgência e emergência envolvendo crianças, adultos e idosos. Metodologia: Vem sendo desenvolvida a prática pedagógica reflexiva, por meio de educação interativa. Esse modelo tem característica viva e oferece constante mudança, através dele o discente torna-se parte da construção do conhecimento. Resultados: A Liga de Enfermagem em Urgência e Emergência iniciou suas atividades em abril de 2017 e já tem realizado ações educativas junto à comunidade, informando e conscientizando a população sobre os processos de suporte básico de vida, prevenção de acidentes domésticos e primeiros socorros. Atualmente, conta com 30 ligantes. São realizadas reuniões periódicas nas quais ocorrem capacitações internas e planejamentos de atividades de extensão. Considerações Finais: Percebe-se que esse projeto de extensão apresenta contribuições tanto para os ligantes, quanto para a comunidade alcançada por meio de suas ações desenvolvidas, as quais proporcionam uma formação cidadã de profissionais enfermeiros, e também, educação permanente para a comunidad

    Oscillations and interactions of dark and dark-bright solitons in Bose-Einstein condensates

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    Solitons are among the most distinguishing fundamental excitations in a wide range of non-linear systems such as water in narrow channels, high speed optical communication, molecular biology and astrophysics. Stabilized by a balance between spreading and focusing, solitons are wavepackets, which share some exceptional generic features like form-stability and particle-like properties. Ultra-cold quantum gases represent very pure and well-controlled non-linear systems, therefore offering unique possibilities to study soliton dynamics. Here we report on the first observation of long-lived dark and dark-bright solitons with lifetimes of up to several seconds as well as their dynamics in highly stable optically trapped 87^{87}Rb Bose-Einstein condensates. In particular, our detailed studies of dark and dark-bright soliton oscillations reveal the particle-like nature of these collective excitations for the first time. In addition, we discuss the collision between these two types of solitary excitations in Bose-Einstein condensates.Comment: 9 pages, 4 figure

    CP asymmetry in BϕKSB \to \phi K_S in a general two-Higgs-doublet model with fourth-generation quarks

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    We discuss the time-dependent CP asymmetry of decay BϕKSB \to \phi K_S in an extension of the Standard Model with both two Higgs doublets and additional fourth-generation quarks. We show that although the Standard Model with two-Higgs-doublet and the Standard model with fourth generation quarks alone are not likely to largely change the effective sin2β\sin 2 \beta from the decay of BϕKSB \to \phi K_S , the model with both additional Higgs doublet and fourth-generation quarks can easily account for the possible large negative value of sin2β\sin 2 \beta without conflicting with other experimental constraints. In this model, additional large CP violating effects may arise from the flavor changing Yukawa interactions between neutral Higgs bosons and the heavy fourth generation down type quark, which can modify the QCD penguin contributions. With the constraints obtained from bssˉsb \to s \bar{s} s processes such as BXsγB \to X_s \gamma and ΔmBs0\Delta m_{B_s^0}, this model can lead to the effective sin2β\sin 2 \beta to be as large as 0.4- 0.4 in the CP asymmetry of BϕKSB \to \phi K_S.Comment: 13 pages, 5 figures, references added, to appear in Eur.Phys.J.

    Evidence for an Excess of Soft Photons in Hadronic Decays of Z^0

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    Soft photons inside hadronic jets converted in front of the DELPHI main tracker (TPC) in events of qqbar disintegrations of the Z^0 were studied in the kinematic range 0.2 < E_gamma < 1 GeV and transverse momentum with respect to the closest jet direction p_T < 80 MeV/c. A clear excess of photons in the experimental data as compared to the Monte Carlo predictions is observed. This excess (uncorrected for the photon detection efficiency) is (1.17 +/- 0.06 +/- 0.27) x 10^{-3} gamma/jet in the specified kinematic region, while the expected level of the inner hadronic bremsstrahlung (which is not included in the Monte Carlo) is (0.340 +/- 0.001 +/- 0.038) x 10^{-3} gamma/jet. The ratio of the excess to the predicted bremsstrahlung rate is then (3.4 +/- 0.2 +/- 0.8), which is similar in strength to the anomalous soft photon signal observed in fixed target experiments with hadronic beams.Comment: 37 pages, 9 figures, Accepted by Eur. Phys. J.

    T-Cell Memory Responses Elicited by Yellow Fever Vaccine are Targeted to Overlapping Epitopes Containing Multiple HLA-I and -II Binding Motifs

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    The yellow fever vaccines (YF-17D-204 and 17DD) are considered to be among the safest vaccines and the presence of neutralizing antibodies is correlated with protection, although other immune effector mechanisms are known to be involved. T-cell responses are known to play an important role modulating antibody production and the killing of infected cells. However, little is known about the repertoire of T-cell responses elicited by the YF-17DD vaccine in humans. In this report, a library of 653 partially overlapping 15-mer peptides covering the envelope (Env) and nonstructural (NS) proteins 1 to 5 of the vaccine was utilized to perform a comprehensive analysis of the virus-specific CD4+ and CD8+ T-cell responses. The T-cell responses were screened ex-vivo by IFN-γ ELISPOT assays using blood samples from 220 YF-17DD vaccinees collected two months to four years after immunization. Each peptide was tested in 75 to 208 separate individuals of the cohort. The screening identified sixteen immunodominant antigens that elicited activation of circulating memory T-cells in 10% to 33% of the individuals. Biochemical in-vitro binding assays and immunogenetic and immunogenicity studies indicated that each of the sixteen immunogenic 15-mer peptides contained two or more partially overlapping epitopes that could bind with high affinity to molecules of different HLAs. The prevalence of the immunogenicity of a peptide in the cohort was correlated with the diversity of HLA-II alleles that they could bind. These findings suggest that overlapping of HLA binding motifs within a peptide enhances its T-cell immunogenicity and the prevalence of the response in the population. In summary, the results suggests that in addition to factors of the innate immunity, "promiscuous" T-cell antigens might contribute to the high efficacy of the yellow fever vaccines. © 2013 de Melo et al
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