255 research outputs found
Multi-Timescale Perceptual History Resolves Visual Ambiguity
When visual input is inconclusive, does previous experience aid the visual system in attaining an accurate perceptual interpretation? Prolonged viewing of a visually ambiguous stimulus causes perception to alternate between conflicting interpretations. When viewed intermittently, however, ambiguous stimuli tend to evoke the same percept on many consecutive presentations. This perceptual stabilization has been suggested to reflect persistence of the most recent percept throughout the blank that separates two presentations. Here we show that the memory trace that causes stabilization reflects not just the latest percept, but perception during a much longer period. That is, the choice between competing percepts at stimulus reappearance is determined by an elaborate history of prior perception. Specifically, we demonstrate a seconds-long influence of the latest percept, as well as a more persistent influence based on the relative proportion of dominance during a preceding period of at least one minute. In case short-term perceptual history and long-term perceptual history are opposed (because perception has recently switched after prolonged stabilization), the long-term influence recovers after the effect of the latest percept has worn off, indicating independence between time scales. We accommodate these results by adding two positive adaptation terms, one with a short time constant and one with a long time constant, to a standard model of perceptual switching
Dynamical Symmetry and Quantum Information Processing with Electromagnetically Induced Transparency
We study in detail the interesting dynamical symmetry and its applications in
various atomic systems with electromagnetically induced transparency (EIT) in
this paper. By discovering the symmetrical Lie group of various atomic systems,
such as single-atomic-ensemble composed of complex -level atoms, and
-atomic-ensemble and even multi-atomic-ensemble system composed of of
-level atoms etc., one can obtain the general definition of dark-state
polaritons (DSPs), and then the dark-states of these different systems. The
symmetrical properties of the multi-level system and multi-atomic-ensemble
system are shown to be dependent on some characteristic parameters of the EIT
system. Furthermore, a controllable scheme to generate quantum entanglement
between lights or atoms via quantized DSPs theory is discussed and the
robustness of this scheme is analyzed by confirming the validity of adiabatic
passage conditions in this paper.Comment: 14pages, 2figures, Phys. Lett. A, In prin
Fitting the incidence data from the city of Campinas, Brazil, based on dengue transmission modellings considering time-dependent entomological parameters
FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFour time-dependent dengue transmission models are considered in order to fit the incidence data from the City of Campinas, Brazil, recorded from October 1st 1995 to September 30th 2012. The entomological parameters are allowed to depend on temperature and precipitation, while the carrying capacity and the hatching of eggs depend only on precipitation. The whole period of incidence of dengue is split into four periods, due to the fact that the model is formulated considering the circulation of only one serotype. Dengue transmission parameters from human to mosquito and mosquito to human are fitted for each one of the periods. The time varying partial and overall effective reproduction numbers are obtained to explain the incidence of dengue provided by the models.Four time-dependent dengue transmission models are considered in order to fit the incidence data from the City of Campinas, Brazil, recorded from October 1st 1995 to September 30th 2012. The entomological parameters are allowed to depend on temperature and precipitation, while the carrying capacity and the hatching of eggs depend only on precipitation. The whole period of incidence of dengue is split into four periods, due to the fact that the model is formulated considering the circulation of only one serotype. Dengue transmission parameters from human to mosquito and mosquito to human are fitted for each one of the periods. The time varying partial and overall effective reproduction numbers are obtained to explain the incidence of dengue provided by the models113FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO2009/15098-
Microwave amplification with nanomechanical resonators
Sensitive measurement of electrical signals is at the heart of modern science
and technology. According to quantum mechanics, any detector or amplifier is
required to add a certain amount of noise to the signal, equaling at best the
energy of quantum fluctuations. The quantum limit of added noise has nearly
been reached with superconducting devices which take advantage of
nonlinearities in Josephson junctions. Here, we introduce a new paradigm of
amplification of microwave signals with the help of a mechanical oscillator. By
relying on the radiation pressure force on a nanomechanical resonator, we
provide an experimental demonstration and an analytical description of how the
injection of microwaves induces coherent stimulated emission and signal
amplification. This scheme, based on two linear oscillators, has the advantage
of being conceptually and practically simpler than the Josephson junction
devices, and, at the same time, has a high potential to reach quantum limited
operation. With a measured signal amplification of 25 decibels and the addition
of 20 quanta of noise, we anticipate near quantum-limited mechanical microwave
amplification is feasible in various applications involving integrated
electrical circuits.Comment: Main text + supplementary information. 14 pages, 3 figures (main
text), 18 pages, 6 figures (supplementary information
Eight common genetic variants associated with serum dheas levels suggest a key role in ageing mechanisms
Dehydroepiandrosterone sulphate (DHEAS) is the most abundant circulating steroid secreted by adrenal glands-yet its function is unknown. Its serum concentration declines significantly with increasing age, which has led to speculation that a relative DHEAS deficiency may contribute to the development of common age-related diseases or diminished longevity. We conducted a meta-analysis of genome-wide association data with 14,846 individuals and identified eight independent common SNPs associated with serum DHEAS concentrations. Genes at or near the identified loci include ZKSCAN5 (rs11761528; p = 3.15×10-36), SULT2A1 (rs2637125; p = 2.61×10-19), ARPC1A (rs740160; p = 1.56×10-16), TRIM4 (rs17277546; p = 4.50×10-11), BMF (rs7181230; p = 5.44×10-11), HHEX (rs2497306; p = 4.64×10-9), BCL2L11 (rs6738028; p = 1.72×10-8), and CYP2C9 (rs2185570; p = 2.29×10-8). These genes are associated with type 2 diabetes, lymphoma, actin filament assembly, drug and xenobiotic metabolism, and zinc finger proteins. Several SNPs were associated with changes in gene expression levels, and the related genes are connected to biological pathways linking DHEAS with ageing. This study provides much needed insight into the function of DHEAS
Health Care Support Issues for Internationally Adopted Children: A Qualitative Approach to the Needs and Expectations of Families
International audienceBACKGROUND: Families of internationally adopted children may face specific problems with which general practitioners (GPs) may not be familiar. The aim of the study was to explore problems faced by families before, during and after the arrival of their internationally adopted child and to assess the usefulness of a specific medical structure for internationally adopted children, which could be a resource for the GP. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a qualitative study using individual semistructured guided conversations and interviewed 21 families that had adopted a total of 26 children internationally in the Puy de Dome department, France, in 2003. Quantitative data were used to describe the pathologies diagnosed and the investigations performed.Our study showed that the history of these families, from the start of the adoption project to its achievement, is complex and warrants careful analysis. Health-care providers should not only consider the medical aspects of adoption, but should also be interested in the histories of these families, which may play a role in the forming of attachments between the adoptee and their adoptive parents and prevent further trouble during the development of the child. We also showed that adoptive parents have similar fears or transient difficulties that may be resolved quickly by listening and reassurance. Most such families would support the existence of a specific medical structure for internationally adopted children, which could be a resource for the general practitioner. However, the health-care providers interviewed were divided on the subject and expressed their fear that a special consultation could be stigmatizing to children and families. CONCLUSIONS/SIGNIFICANCE: A specific consultation with well-trained and experienced practitioners acting in close collaboration with GPs and paediatricians may be of help in better understanding and supporting adopted children and their families
Filarial Lymphedema Is Characterized by Antigen- Specific Th1 and Th17 Proinflammatory Responses and a Lack of Regulatory T Cells
Background: Lymphatic filariasis can be associated with development of serious pathology in the form of lymphedema,
hydrocele, and elephantiasis in a subset of infected patients.
Methods and Findings: To elucidate the role of CD4+ T cell subsets in the development of lymphatic pathology, we
examined specific sets of cytokines in individuals with filarial lymphedema in response to parasite antigen (BmA) and
compared them with responses from asymptomatic infected individuals. We also examined expression patterns of Toll-like
receptors (TLR1–10) and Nod-like receptors (Nod1, Nod2, and NALP3) in response to BmA. BmA induced significantly higher
production of Th1-type cytokines—IFN-c and TNF-a—in patients with lymphedema compared with asymptomatic
individuals. Notably, expression of the Th17 family of cytokines—IL-17A, IL-17F, IL-21, and IL-23—was also significantly
upregulated by BmA stimulation in lymphedema patients. In contrast, expression of Foxp3, GITR, TGFb, and CTLA-4, known
to be expressed by regulatory T cells, was significantly impaired in patients with lymphedema. BmA also induced
significantly higher expression of TLR2, 4, 7, and 9 as well Nod1 and 2 mRNA in patients with lymphedema compared with
asymptomatic controls.
Conclusion: Our findings implicate increased Th1/Th17 responses and decreased regulatory T cells as well as regulation of
Toll- and Nod-like receptors in pathogenesis of filarial lymphedema
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