Inhibited spontaneous emission of quantum dots observed in a 3D photonic band gap

We present time-resolved emission experiments of semiconductor quantum dots in silicon 3D inverse-woodpile photonic band gap crystals. A systematic study is made of crystals with a range of pore radii to tune the band gap relative to the emission frequency. The decay rates averaged over all dipole orientations are inhibited by a factor of 10 in the photonic band gap and enhanced up to 2? outside the gap, in agreement with theory. We discuss the effects of spatial inhomogeneity, nonradiative decay, and transition dipole orientations on the observed inhibition in the band gap.Comment: 5 figures, update author lis

Unraveling Time Series Dynamics: Evaluating Partial Autocorrelation Function Distribution and Its Implications

The objective of this paper is to assess the distribution of the Partial Autocorrelation Function (PACF), both theoretically and empirically, emphasizing its crucial role in modeling and forecasting time series data. Additionally, it evaluates the deviation of the sum of sample PACF from normality: identifying the lag at which departure occurs. Our investigation reveals that the sum of the sample PACF, and consequently its components, diverges from the expected normal distribution beyond a certain lag. This observation challenges conventional assumptions in time series modeling and forecasting, indicating a necessity for reassessment of existing methodologies. Through our analysis, we illustrate the practical implications of our findings using real-world scenarios, highlighting their significance in unraveling complex data patterns. This study delves into 185 years of monthly Bank of England Rate data, utilizing this extensive dataset to conduct an empirical analysis. Furthermore, our research paves the way for future exploration, offering insights into the complexities and potential revisions in time series analysis, modeling, and forecasting

Exploring the Depths of the Autocorrelation Function: Its Departure from Normality

In this article, we study the autocorrelation function (ACF), which is a crucial element in time series analysis. We compare the distribution of the ACF, both from a theoretical and empirical point of view. We focus on white noise processes (WN), i.e., uncorrelated, centered, and identically distributed variables, whose ACFs are supposed to be asymptotically independent and converge towards the same normal distribution. But, the study of the sum of the sample ACF contradicts this property. Thus, our findings reveal a deviation of the sample ACF from normality beyond a specific lag. Note that this phenomenon is observed for white noise of varying lengths, and evenforn the residuals of an ARMA

A Support Vector Machine Based Approach for Predicting the Risk of Freshwater Disease Emergence in England

Disease emergence, in the last decades, has had increasingly disproportionate impacts on aquatic freshwater biodiversity. Here, we developed a new model based on Support Vector Machines (SVM) for predicting the risk of freshwater fish disease emergence in England. Following a rigorous training process and simulations, the proposed SVM model was validated and reported high accuracy rates for predicting the risk of freshwater fish disease emergence in England. Our findings suggest that the disease monitoring strategy employed in England could be successful at preventing disease emergence in certain parts of England, as areas in which there were high fish introductions were not correlated with high disease emergence (which was to be expected from the literature). We further tested our model’s predictions with actual disease emergence data using Chi-Square tests and test of Mutual Information. The results identified areas that require further attention and resource allocation to curb future freshwater disease emergence successfully

Multi-channel recordings reveal age-related differences in the sleep of juvenile and adult zebra finches

Abstract Despite their phylogenetic differences and distinct pallial structures, mammals and birds show similar electroencephalography (EEG) traces during sleep, consisting of distinct rapid eye movement (REM) sleep and slow wave sleep (SWS) stages. Studies in human and a limited number of other mammalian species show that this organization of sleep into interleaving stages undergoes radical changes during lifetime. Do these age-dependent variations in sleep patterns also occur in the avian brain? Does vocal learning have an effect on sleep patterns in birds? To answer these questions, we recorded multi-channel sleep EEG from juvenile and adult zebra finches for several nights. Whereas adults spent more time in SWS and REM sleep, juveniles spent more time in intermediate sleep (IS). The amount of IS was significantly larger in male juveniles engaged in vocal learning compared to female juveniles, which suggests that IS could be important for vocal learning. In addition, we observed that functional connectivity increased rapidly during maturation of young juveniles, and was stable or declined at older ages. Synchronous activity during sleep was larger for recording sites in the left hemisphere for both juveniles and adults, and generally intra-hemispheric synchrony was larger than inter-hemispheric synchrony during sleep. A graph theory analysis revealed that in adults, highly correlated EEG activity tended to be distributed across fewer networks that were spread across a wider area of the brain, whereas in juveniles, highly correlated EEG activity was distributed across more numerous, albeit smaller, networks in the brain. Overall, our results reveal that significant changes occur in the neural signatures of sleep during maturation in an avian brain

Investigation on polycarbonate nanomembrane production based on alpha particles irradiation

Track-etched membranes were prepared in the Dosimetry Laboratory of Agricultural, Medical and Industrial Research School by exposing polycarbonate (PC) films with a thickness of about 20 μm to alpha particles emitted from 241Am followed by chemical etching in sodium hydroxide (NaOH) at different temperatures and solution concentrations. The PC films were prepared using the method of chemical solving, forming and drying in a vacuum oven. The etching rate of PC was related to the concentration of etching solution, etching temperature and time. Therefore, a series of track-etched membranes were produced using different etching parameters. The relation between the etching rate and the etching parameters were established from experimental data and can be used to control the average pore sizes of the PC track-etched membrane. The pore sizes and their structures were studied by an optical microscope (OM) and a scanning electron microscope (SEM) and the obtained results indicated that the pores across the PC films are cylindrically shaped

Fetal Sex and Preterm Birth.

Rates of preterm birth vary between different populations and ethnic groups. Epidemiologic studies have suggested that the incidence of preterm birth is also higher in pregnancies carrying a male fetus; the male:female difference is greater in earlier preterm pregnancy. Placental or chorion trophoblast cells from pregnancies with a male fetus produced more pro-inflammatory TNFα in response to LPS stimulation and less anti-inflammatory IL-10 and granulocyte colony stimulating factor (G-CSF) than cells from pregnancies with a female fetus, more prostaglandin synthase (PTGS-2) and less prostaglandin dehydrogenase (PGDH). These results suggest that in the presence of a male fetus the trophoblast has the potential to generate a more pro-inflammatory environment. Maturation of the fetal hypothalamic-pituitary-adrenal axis and expression of placental genes, particularly 11β hydroxysteroid dehydrogenase-2 are also expressed in a sex dependent manner, consistent with the sex-biasing influences on gene networks. Sex differences in these activities may affect clinical outcomes of pre- and post-dates pregnancies and fetal/newborn wellbeing. These factors need consideration in studies of placental function and in the development of personalized strategies for the diagnosis of preterm labor and postnatal healt