Prior context in audition informs binding and shapes simple features

A perceptual phenomenon is reported, whereby prior acoustic context has a large, rapid and long-lasting effect on a basic auditory judgement. Pairs of tones were devised to include ambiguous transitions between frequency components, such that listeners were equally likely to report an upward or downward ‘pitch’ shift between tones. We show that presenting context tones before the ambiguous pair almost fully determines the perceived direction of shift. The context effect generalizes to a wide range of temporal and spectral scales, encompassing the characteristics of most realistic auditory scenes. Magnetoencephalographic recordings show that a relative reduction in neural responsivity is correlated to the behavioural effect. Finally, a computational model reproduces behavioural results, by implementing a simple constraint of continuity for binding successive sounds in a probabilistic manner. Contextual processing, mediated by ubiquitous neural mechanisms such as adaptation, may be crucial to track complex sound sources over time

Higher dimensional dust collapse with a cosmological constant

The general solution of the Einstein equation for higher dimensional (HD) spherically symmetric collapse of inhomogeneous dust in presence of a cosmological term, i.e., exact interior solutions of the Einstein field equations is presented for the HD Tolman-Bondi metrics imbedded in a de Sitter background. The solution is then matched to exterior HD Scwarschild-de Sitter. A brief discussion on the causal structure singularities and horizons is provided. It turns out that the collapse proceed in the same way as in the Minkowski background, i.e., the strong curvature naked singularities form and that the higher dimensions seem to favor black holes rather than naked singularities.Comment: 7 Pages, no figure

Organizing recurrent network dynamics by task-computation to enable continual learning

Biological systems face dynamic environments that require continual learning. It is not well understood how these systems balance the tension between flexibility for learning and robustness for memory of previous behaviors. Continual learning without catastrophic interference also remains a challenging problem in machine learning. Here, we develop a novel learning rule designed to minimize interference between sequentially learned tasks in recurrent networks. Our learning rule preserves network dynamics within activity-defined subspaces used for previously learned tasks. It encourages dynamics associated with new tasks that might otherwise interfere to instead explore orthogonal subspaces, and it allows for reuse of previously established dynamical motifs where possible. Employing a set of tasks used in neuroscience, we demonstrate that our approach successfully eliminates catastrophic interference and offers a substantial improvement over previous continual learning algorithms. Using dynamical systems analysis, we show that networks trained using our approach can reuse similar dynamical structures across similar tasks. This possibility for shared computation allows for faster learning during sequential training. Finally, we identify organizational differences that emerge when training tasks sequentially versus simultaneously

Non-vacuum Solutions of Bianchi Type VI_0 Universe in f(R) Gravity

In this paper, we solve the field equations in metric f(R) gravity for Bianchi type VI_0 spacetime and discuss evolution of the expanding universe. We find two types of non-vacuum solutions by taking isotropic and anisotropic fluids as the source of matter and dark energy. The physical behavior of these solutions is analyzed and compared in the future evolution with the help of some physical and geometrical parameters. It is concluded that in the presence of isotropic fluid, the model has singularity at $\tilde{t}=0$ and represents continuously expanding shearing universe currently entering into phantom phase. In anisotropic fluid, the model has no initial singularity and exhibits the uniform accelerating expansion. However, the spacetime does not achieve isotropy as $t\rightarrow\infty$ in both of these solutions.Comment: 20 pages, 5 figures, accepted for publication in Astrophys. Space Sc

MicroRNAs targeting oncogenes are down-regulated in pancreatic malignant transformation from benign tumors

BACKGROUND MicroRNA (miRNA) expression profiles have been described in pancreatic ductal adenocarcinoma (PDAC), but these have not been compared with pre-malignant pancreatic tumors. We wished to compare the miRNA expression signatures in pancreatic benign cystic tumors (BCT) of low and high malignant potential with PDAC, in order to identify miRNAs deregulated during PDAC development. The mechanistic consequences of miRNA dysregulation were further evaluated. METHODS Tissue samples were obtained at a tertiary pancreatic unit from individuals with BCT and PDAC. MiRNA profiling was performed using a custom microarray and results were validated using RT-qPCR prior to evaluation of miRNA targets. RESULTS Widespread miRNA down-regulation was observed in PDAC compared to low malignant potential BCT. We show that amongst those miRNAs down-regulated, miR-16, miR-126 and let-7d regulate known PDAC oncogenes (targeting BCL2, CRK and KRAS respectively). Notably, miR-126 also directly targets the KRAS transcript at a "seedless" binding site within its 3'UTR. In clinical specimens, miR-126 was strongly down-regulated in PDAC tissues, with an associated elevation in KRAS and CRK proteins. Furthermore, miR-21, a known oncogenic miRNA in pancreatic and other cancers, was not elevated in PDAC compared to serous microcystic adenoma (SMCA), but in both groups it was up-regulated compared to normal pancreas, implicating early up-regulation during malignant change. CONCLUSIONS Expression profiling revealed 21 miRNAs down-regulated in PDAC compared to SMCA, the most benign lesion that rarely progresses to invasive carcinoma. It appears that miR-21 up-regulation is an early event in the transformation from normal pancreatic tissue. MiRNA expression has the potential to distinguish PDAC from normal pancreas and BCT. Mechanistically the down-regulation of miR-16, miR-126 and let-7d promotes PDAC transformation by post-transcriptional up-regulation of crucial PDAC oncogenes. We show that miR-126 is able to directly target KRAS; re-expression has the potential as a therapeutic strategy against PDAC and other KRAS-driven cancers

Consensus Statement on the Pathology of IgG4-Related Disease

IgG4-related disease is a newly recognized fibro-inflammatory condition characterized by several features: a tendency to form tumefactive lesions in multiple sites; a characteristic histopathological appearance; and—often but not always—elevated serum IgG4 concentrations. An international symposium on IgG4-related disease was held in Boston, MA, on 4–7 October 2011. The organizing committee comprising 35 IgG4-related disease experts from Japan, Korea, Hong Kong, the United Kingdom, Germany, Italy, Holland, Canada, and the United States, including the clinicians, pathologists, radiologists, and basic scientists. This group represents broad subspecialty expertise in pathology, rheumatology, gastroenterology, allergy, immunology, nephrology, pulmonary medicine, oncology, ophthalmology, and surgery. The histopathology of IgG4-related disease was a specific focus of the international symposium. The primary purpose of this statement is to provide practicing pathologists with a set of guidelines for the diagnosis of IgG4-related disease. The diagnosis of IgG4-related disease rests on the combined presence of the characteristic histopathological appearance and increased numbers of IgG4+ plasma cells. The critical histopathological features are a dense lymphoplasmacytic infiltrate, a storiform pattern of fibrosis, and obliterative phlebitis. We propose a terminology scheme for the diagnosis of IgG4-related disease that is based primarily on the morphological appearance on biopsy. Tissue IgG4 counts and IgG4:IgG ratios are secondary in importance. The guidelines proposed in this statement do not supplant careful clinicopathological correlation and sound clinical judgment. As the spectrum of this disease continues to expand, we advocate the use of strict criteria for accepting newly proposed entities or sites as components of the IgG4-related disease spectrum

Optimism during pregnancy and obstetrical outcomes: A systematic review

OBJECTIVE: To ascertain the strength of association between dispositional optimism, assessed with the Revised Life Orientation Test (LOT-R), and obstetrical outcomes, and to evaluate women's social characteristics that may lead to low dispositional optimism during pregnancy. STUDY DESIGN: The research was conducted using MEDLINE, EMBASE, Scopus, Web of Sciences, Cochrane Database, and ClinicalTrial.gov as electronic databases. The articles were identified with the use of a combination of the relevant heading term, key words, and word variants for: "optimism" or "happiness" and "pregnancy" or "obstetrical outcomes", from the inception of each database to June 2019. Review of articles also included the abstracts of all references retrieved from the search. Randomized, cohort, case-control, or case series were all accepted study designs. Only studies reporting obstetrical outcomes in women undergone LOT-R to assess dispositional optimism during pregnancy were included. Obstetrical outcomes included preterm birth, pre-eclampsia and small for gestational age fetuses. All analyses were carried out using the random effects model. Dichotomous variables were analyzed using the odds ratio (OR) with a 95 % confidence interval (95 % CI). No continuous variables were compared in the analysis. Significance level was set at P < 0.05. Heterogeneity was measured using I-squared (Higgins I2). RESULTS: Two prospective cohort studies, including 3,570 pregnancies undergone LOT-R - mostly during the second trimester - were included in the systematic review. Out of the 3,570 pregnancies included, 411 were in the lowest quartile of optimism, according to LOT-R score. Dispositional optimism showed a trend towards lower incidence of preterm birth (7.6 % vs 9.7 %; OR 0.76, CI 0.53-1.09); no difference between women at higher levels and women in the lowest quartile of optimism was found in preeclampsia and small for gestational age. Women at higher levels of dispositional optimism were significantly associated with: age ≥ 30 years; marriage or "marriage-like status"; lower rates of public assistance and smoking; white ethnicity; higher rates of higher education. CONCLUSION: There are limited data on optimism and obstetric outcomes. Higher levels of optimism, evaluated by the LOT-R tool in two studies, are associated with a non-significant decrease in preterm birth

Learning shapes cortical dynamics to enhance integration of relevant sensory input

Adaptive sensory behavior is thought to depend on processing in recurrent cortical circuits, but how dynamics in these circuits shapes the integration and transmission of sensory information is not well understood. Here, we study neural coding in recurrently connected networks of neurons driven by sensory input. We show analytically how information available in the network output varies with the alignment between feedforward input and the integrating modes of the circuit dynamics. In light of this theory, we analyzed neural population activity in the visual cortex of mice that learned to discriminate visual features. We found that over learning, slow patterns of network dynamics realigned to better integrate input relevant to the discrimination task. This realignment of network dynamics could be explained by changes in excitatory-inhibitory connectivity among neurons tuned to relevant features. These results suggest that learning tunes the temporal dynamics of cortical circuits to optimally integrate relevant sensory input

Human African Trypanosomiasis and challenges to its control in Urambo, Kasulu and Kibondo Districts, western Tanzania

A study was carried out to determine the prevalence and management of Human African Trypanosomiasis (HAT) in Urambo, Kasulu and Kibondo districts of western Tanzania. Parasitological surveys for trypanosome and other blood parasites were conducted in selected villages. Interviews with health workers were conducted to explore facility capacity to diagnose and manage HAT. Community knowledge on tsetse and availability of trypanocidal drugs was explored. Results showed that, although health facility records showed HAT is an important public health problem in the three districts, typanosomes were found in 0.6% of the examined individuals in Urambo district only. Malaria parasites with a prevalence of 12.1%, 19.7% and 9.7%, in Urambo, Kibondo and Kasulu, respectively were detected in blood samples from the same individuals examined for trypanosomes. There was poor capacity for most of the health facilities in the diagnosis, treatment and control of HAT. In both districts, communities were knowledgeable of the tsetse identity (82.4%) and had experienced tsetse bites (94%). The majority (91.4%) of the community members knew that they were at risk of acquiring HAT. However, only 29% of the respondents knew that anti-trypanocidal drugs were readily available free of charge from health care facilities. Late treatment seeking behaviour was common in Kasulu and Urambo districts. In conclusion, health facilities in western Tanzania are faced with problems of poor capacity to diagnose and manage HAT and that treatment seeking behaviour among the communities at risk is poor. Efforts should be made to strengthen the capacity of the health facility to handle HAT cases and health education to the population at risk. Keywords: Human African Trypanosomiasis, diagnosis, control, TanzaniaTanzania Health Research Bulletin Vol. 8 (2) 2006: pp. 80-8