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

Childhood socioeconomic position and objectively measured physical capability levels in adulthood: a systematic review and meta-analysis

<p><b>Background:</b> Grip strength, walking speed, chair rising and standing balance time are objective measures of physical capability that characterise current health and predict survival in older populations. Socioeconomic position (SEP) in childhood may influence the peak level of physical capability achieved in early adulthood, thereby affecting levels in later adulthood. We have undertaken a systematic review with meta-analyses to test the hypothesis that adverse childhood SEP is associated with lower levels of objectively measured physical capability in adulthood.</p> <p><b>Methods and Findings:</b> Relevant studies published by May 2010 were identified through literature searches using EMBASE and MEDLINE. Unpublished results were obtained from study investigators. Results were provided by all study investigators in a standard format and pooled using random-effects meta-analyses. 19 studies were included in the review. Total sample sizes in meta-analyses ranged from N = 17,215 for chair rise time to N = 1,061,855 for grip strength. Although heterogeneity was detected, there was consistent evidence in age adjusted models that lower childhood SEP was associated with modest reductions in physical capability levels in adulthood: comparing the lowest with the highest childhood SEP there was a reduction in grip strength of 0.13 standard deviations (95% CI: 0.06, 0.21), a reduction in mean walking speed of 0.07 m/s (0.05, 0.10), an increase in mean chair rise time of 6% (4%, 8%) and an odds ratio of an inability to balance for 5s of 1.26 (1.02, 1.55). Adjustment for the potential mediating factors, adult SEP and body size attenuated associations greatly. However, despite this attenuation, for walking speed and chair rise time, there was still evidence of moderate associations.</p> <p><b>Conclusions:</b> Policies targeting socioeconomic inequalities in childhood may have additional benefits in promoting the maintenance of independence in later life.</p&gt

Doping the holographic Mott insulator

Mott insulators form because of strong electron repulsions, being at the heart of strongly correlated electron physics. Conventionally these are understood as classical "traffic jams" of electrons described by a short-ranged entangled product ground state. Exploiting the holographic duality, which maps the physics of densely entangled matter onto gravitational black hole physics, we show how Mott-insulators can be constructed departing from entangled non-Fermi liquid metallic states, such as the strange metals found in cuprate superconductors. These "entangled Mott insulators" have traits in common with the "classical" Mott insulators, such as the formation of Mott gap in the optical conductivity, super-exchange-like interactions, and form "stripes" when doped. They also exhibit new properties: the ordering wave vectors are detached from the number of electrons in the unit cell, and the DC resistivity diverges algebraically instead of exponentially as function of temperature. These results may shed light on the mysterious ordering phenomena observed in underdoped cuprates.Comment: 27 pages, 9 figures. Accepted in Nature Physic

Psychometric evidence of a brief measure of resilience in non-institutionalized Peruvian older adults

Resilience is understood as the domain of personal resources and contextual factors that allow for a successful coping and enhance positive adaptation to the different stressors during the lifespan, thereby being important for a healthy and successful aging. Nowadays, several brief instruments have been developed to measure resilience, such as the Brief Resilient Coping Scale (BRCS), an instrument that measures the ability of people to confront stress in an adaptive way. In this vein, the study provides evidence of the validity and reliability of the BRCS in non-institutionalized older adults in Peru. Two hundred thirty-six elderly people of both genders, 78.4% women and 21.6% men, with a mean age of 72.8 years (SD= 6.90), who answered the Spanish version of the BRCS and other scales to measure satisfaction with life, humor as coping, and depression. Confirmatory factor analysis corroborates the one-dimensional structure of the BRCS. The coefficients of internal consistency, Chronbach's alpha and omega, indicated an adequate reliability of the BRCS. Both the adjustment indices of the model and the values of the coefficients of reliability were higher compared to those reported in the literature. The BRCS showed positive and significant correlations with satisfaction with life and humor as coping (p < .01). Likewise, negative and significant correlations were observed with depression (p < .01). The results show that the BRCS has proved valid and reliable, supporting its use as a short measure of resilience in older Peruvians.La resiliencia es comprendida como el dominio de recursos personales y factores contextuales que permiten un afrontamiento exitoso y el logro de una adaptación positiva ante los diferentes estresores que aparecen a lo largo de la vida, siendo así importante dentro del proceso de envejecimiento saludable y exitoso. En la actualidad se han desarrollado instrumentos breves para la medición de la resiliencia como la escala breve de resiliencia (BRCS - Brief Resilient Coping Scale) que evalúa la capacidad de los individuos para hacer frente al estrés de manera adaptativa. En este sentido, el estudio ofrece evidencia de validez y fiabilidad de la BRCS en adultos mayores no institucionalizados peruanos. Se contó con la participación de 236 adultos mayores con una edad promedio de 72.8 años (DT = 6.90) de los cuales el 78.4% eran mujeres y el 21.6% hombres, quienes respondieron la versión en español del BRCS y otras escalas para medir la satisfacción con la vida, humor como afrontamiento y depresión. Mediante el análisis factorial confirmatorio se corrobora la estructura unidimensional de la BRCS. Los coeficientes de consistencia interna alfa de Cronbach y omega indicaron una adecuada fiabilidad de la BRCS. Tanto los índices de ajuste del modelo como los valores de los coeficientes de fiabilidad fueron mejores en comparación con los reportados en la literatura. La BRCS mostró una correlación positiva significativa con la satisfacción con la vida y el humor como afrontamiento (p < .01). Asimismo, se observó una correlación negativa significativa con depresión (p < .01). Los resultados muestran que la BRCS cuenta con evidencias de validez y fiabilidad que avala su empleo como medida breve de la resiliencia en adultos mayores peruanos

Plasma levels of alpha1-antichymotrypsin and secretory leukocyte proteinase inhibitor in healthy and chronic obstructive pulmonary disease (COPD) subjects with and without severe α1-antitrypsin deficiency

BACKGROUND: Individuals with severe Z α1-antitrypsin (AAT) deficiency have a considerably increased risk of developing chronic obstructive lung disease (COPD). It has been hypothesized that compensatory increases in levels of other protease inhibitors mitigate the effects of this AAT deficiency. We analysed plasma levels of AAT, α1-antichymotrypsin (ACT) and secretory leukocyte protease inhibitor (SLPI) in healthy (asymptomatic) and COPD subjects with and without AAT deficiency. METHODS: Studied groups included: 71 asymptomatic AAT-deficient subjects (ZZ, n = 48 and SZ, n = 23, age 31 ± 0.5) identified during Swedish neonatal screening for AAT deficiency between 1972 and 1974; age-matched controls (MM, n = 57, age 30.7 ± 0.6); older asymptomatic ZZ (n = 10); healthy MM (n = 20, age 53 ± 9.6); and COPD patients (ZZ, n = 10, age 47.4 ± 11 and MM, n = 10, age 59.4 ± 6.7). Plasma levels of SLPI, AAT and ACT were analysed using ELISA and immunoelectrophoresis. RESULTS: No significant difference was found in plasma ACT and SLPI levels between the healthy MM and the ZZ or SZ subjects in the studied groups. Independent of the genetic variant, subjects with COPD (n = 19) had elevated plasma levels of SLPI and ACT relative to controls (n = 153) (49.5 ± 7.2 vs 40.7 ± 9.1 ng/ml, p < 0.001 and 0.52 ± 0.19 vs 0.40 ± 0.1 mg/ml, p < 0.05, respectively). CONCLUSION: Our findings show that plasma levels of ACT and SLPI are not elevated in subjects with genetic AAT deficiency compared MM controls and do not appear to compensate for the deficiency of plasma AAT

Accurate Real-Time PCR Strategy for Monitoring Bloodstream Parasitic Loads in Chagas Disease Patients

Infection with the parasite Trypanosoma cruzi (T. cruzi), causing American trypanosomiasis or Chagas disease, remains a major public health concern in 21 endemic countries of America, with an estimated prevalence of 8 million infected people. Chagas disease shows a variable clinical course, ranging from asymptomatic to chronic stages with low parasitaemias, whose severest form is heart disease. Diagnosis at the asymptomatic and chronic stages is based on serological detection of anti-T. cruzi antibodies, because conventional parasitological methods lack sensitivity. Current chemotherapies are more effective in recent infections than in the chronic adult population. The criterion of cure relies on serological conversion to negative, which may occur only years after treatment, requiring long-term follow-up. In this context, we aimed to develop a real-time PCR assay targeted to repetitive sequences of T. cruzi for sensitive quantitation of parasitic load in peripheral blood of infected patients. It was applied to monitor treatment response of infected children, allowing rapid evaluation of drug efficacy as well as detection of treatment failure. It was also used for early diagnosis of chagasic reactivation in end-stage heart disease patients who received immunosuppressive drugs after cardiac transplantation. This laboratory strategy may constitute a novel parasitological tool for prompt and sensitive evaluation of anti-parasitic treatment of Chagas disease