Coherent spinor dynamics in a spin-1 Bose condensate

Collisions in a thermal gas are perceived as random or incoherent as a consequence of the large numbers of initial and final quantum states accessible to the system. In a quantum gas, e.g. a Bose-Einstein condensate or a degenerate Fermi gas, the phase space accessible to low energy collisions is so restricted that collisions be-come coherent and reversible. Here, we report the observation of coherent spin-changing collisions in a gas of spin-1 bosons. Starting with condensates occupying two spin states, a condensate in the third spin state is coherently and reversibly created by atomic collisions. The observed dynamics are analogous to Josephson oscillations in weakly connected superconductors and represent a type of matter-wave four-wave mixing. The spin-dependent scattering length is determined from these oscillations to be -1.45(18) Bohr. Finally, we demonstrate coherent control of the evolution of the system by applying differential phase shifts to the spin states using magnetic fields.Comment: 19 pages, 3 figure

Learning Relations from Social Tagging Data

An interesting research direction is to discover structured knowledge from user generated data. Our work aims to find relations among social tags and organise them into hierarchies so as to better support discovery and search for online users. We cast relation discovery in this context to a binary classification problem in supervised learning. This approach takes as input features of two tags extracted using probabilistic topic modelling, and predicts whether a broader-narrower relation holds between them. Experiments were conducted using two large, real-world datasets, the Bibsonomy dataset which is used to extract tags and their features, and the DBpedia dataset which is used as the ground truth. Three sets of features were designed and extracted based on topic distributions, similarity and probabilistic associations. Evaluation results with respect to the ground truth demonstrate that our method outperforms existing ones based on various features and heuristics. Future studies are suggested to study the Knowledge Base Enrichment from folksonomies and deep neural network approaches to process tagging data

A 1.3 mm SMA Survey of 29 Variable Young Stellar Objects

Young stellar objects (YSOs) may undergo periods of active accretion (outbursts), during which the protostellar accretion rate is temporarily enhanced by a few orders of magnitude. Whether or not these accretion outburst YSOs possess similar dust/gas reservoirs to each other, and whether or not their dust/gas reservoirs are similar as quiescent YSOs, are issues not yet clarified. The aim of this work is to characterize the millimeter thermal dust emission properties of a statistically significant sample of long and short duration accretion outburst YSOs (i.e., FUors and EXors) and the spectroscopically identified candidates of accretion outbursting YSOs (i.e., FUor-like objects). We have carried out extensive Submillimeter Array (SMA) observations mostly at $\sim$225 GHz (1.33 mm) and $\sim$272 GHz (1.10 mm), from 2008 to 2017. We covered accretion outburst YSOs located at $$3-$\sigma$ significance. Detected sources except for the two cases of V883 Ori and NGC 2071 MM3 were observed with $\sim$1$"$ angular resolution. Overall our observed targets show a systematically higher millimeter luminosity distribution than those of the $M_{*}>$0.3 $M_{\odot}$ Class II YSOs in the nearby ($\lesssim$400 pc) low-mass star-forming molecular clouds (e.g., Taurus, Lupus, Upp Scorpio, and Chameleon I). In addition, at 1 mm our observed confirmed binaries or triple-system sources are systematically fainter than the rest of the sources even though their 1 mm fluxes are broadly distributed. We may have detected $\sim$30-60\% millimeter flux variability from V2494 Cyg and V2495 Cyg, from the observations separated by $\sim$1 year

EmptyDrops: distinguishing cells from empty droplets in droplet-based single-cell RNA sequencing data.

Droplet-based single-cell RNA sequencing protocols have dramatically increased the throughput of single-cell transcriptomics studies. A key computational challenge when processing these data is to distinguish libraries for real cells from empty droplets. Here, we describe a new statistical method for calling cells from droplet-based data, based on detecting significant deviations from the expression profile of the ambient solution. Using simulations, we demonstrate that EmptyDrops has greater power than existing approaches while controlling the false discovery rate among detected cells. Our method also retains distinct cell types that would have been discarded by existing methods in several real data sets

Deep Sequencing the Transcriptome Reveals Seasonal Adaptive Mechanisms in a Hibernating Mammal

Mammalian hibernation is a complex phenotype involving metabolic rate reduction, bradycardia, profound hypothermia, and a reliance on stored fat that allows the animal to survive for months without food in a state of suspended animation. To determine the genes responsible for this phenotype in the thirteen-lined ground squirrel (Ictidomys tridecemlineatus) we used the Roche 454 platform to sequence mRNA isolated at six points throughout the year from three key tissues: heart, skeletal muscle, and white adipose tissue (WAT). Deep sequencing generated approximately 3.7 million cDNA reads from 18 samples (6 time points ×3 tissues) with a mean read length of 335 bases. Of these, 3,125,337 reads were assembled into 140,703 contigs. Approximately 90% of all sequences were matched to proteins in the human UniProt database. The total number of distinct human proteins matched by ground squirrel transcripts was 13,637 for heart, 12,496 for skeletal muscle, and 14,351 for WAT. Extensive mitochondrial RNA sequences enabled a novel approach of using the transcriptome to construct the complete mitochondrial genome for I. tridecemlineatus. Seasonal and activity-specific changes in mRNA levels that met our stringent false discovery rate cutoff (1.0×10−11) were used to identify patterns of gene expression involving various aspects of the hibernation phenotype. Among these patterns are differentially expressed genes encoding heart proteins AT1A1, NAC1 and RYR2 controlling ion transport required for contraction and relaxation at low body temperatures. Abundant RNAs in skeletal muscle coding ubiquitin pathway proteins ASB2, UBC and DDB1 peak in October, suggesting an increase in muscle proteolysis. Finally, genes in WAT that encode proteins involved in lipogenesis (ACOD, FABP4) are highly expressed in August, but gradually decline in expression during the seasonal transition to lipolysis

Tradeoff between Biomass and Flavonoid Accumulation in White Clover Reflects Contrasting Plant Strategies

An outdoor study was conducted to examine relationships between plant productivity and stress-protective phenolic plant metabolites. Twenty-two populations of the pasture legume white clover were grown for 4½ months during spring and summer in Palmerston North, New Zealand. The major phenolic compounds identified and quantified by HPLC analysis were glycosides of the flavonoids quercetin and kaempferol. Multivariate analysis revealed a trade-off between flavonoid accumulation and plant productivity attributes. White clover populations with high biomass production, large leaves and thick tap roots showed low levels of quercetin glycoside accumulation and low quercetin:kaempferol ratios, while the opposite was true for less productive populations. The latter included stress-resistant ecotypes from Turkey and China, and the analysis also identified highly significant positive relationships of quercetin glycoside accumulation with plant morphology (root:shoot ratio). Importantly, a high degree of genetic variation was detected for most of the measured traits. These findings suggest merit for considering flavonoids such as quercetin as potential selection criteria in the genetic improvement of white clover and other crops

Interlaminar Fracture Toughness Evaluation in Glass/Epoxy Composites Using Acoustic Emission and Finite Element Methods

© 2014, ASM International. Delamination is one of the most common modes of failure in laminated composites and it leads to the loss of structural strength and stiffness. In this paper, mode I, mode II, and mixed of these pure modes were investigated using mechanical data, Finite Element Method (FEM) and Acoustic Emission (AE) signals. Experimental data were obtained from insitu monitoring of glass/epoxy laminated composites with different lay-ups when subjected to different modes of failure. The main objective was to investigate the behavior of delamination propagation and to evaluate the critical value of the strain energy which is required for onset of the delamination (GC). For the identification of interlaminar fracture toughness of the specimens, four methods were used: (a) ASTM standard methods, (b) FEM analysis, (c) AE method, and (d) sentry function method which is a function of mechanical and AE behaviors of the specimens. The results showed that the GC values obtained by the sentry function method and FEM analysis were in a close agreement with the results of nonlinearity methods which is recommended in the ASTM standards. It was also found that the specimens under different loading conditions and various lay-up have different GC values. These differences are related to different stress components distribution in the specimens which induce various damage mechanisms. Accordingly, stress components distribution obtained from FEM analyses were in agreement with SEM observations of the damaged surfaces of the specimens

The motor development of orphaned children with and without HIV: Pilot exploration of foster care and residential placement

<p>Abstract</p> <p>Background</p> <p>The AIDS epidemic has lead to an increase in orphaned children who need residential care. It is known that HIV leads to delayed motor development. However, the impact of place of residence on motor function has not been investigated in the South African context. The aim of the study was therefore to establish if children in institutionalised settings performed better or worse in terms of gross motor function than their counterparts in foster care. A secondary objective was to compare the performance of children with HIV in these two settings with those of children who were HIV negative.</p> <p>Methods</p> <p>Forty-four children both with and without HIV, were recruited from institutions and foster care families in Cape Town. The Peabody Development Motor Scale (PDMS II) was used to calculate the total motor quotient (TMQ) at baseline and six months later. Comparisons of TMQ were made between residential settings and between children with and without HIV.</p> <p>Results</p> <p>Twenty-one children were infected with HIV and were significantly delayed compared to their healthy counterparts. Antiretroviral therapy was well managed among the group but did not appear to result in restoration of TMQ to normal over the study period. HIV status and place of residence emerged as a predictor of TMQ with children in residential care performing better than their counterparts in foster care. All children showed improvement over the six months of study.</p> <p>Conclusions</p> <p>Foster parents were well supported administratively in the community by social welfare services but their children might have lacked stimulation in comparison to those in institutional settings. This could have been due to a lack of resources and knowledge regarding child development. The assumption that foster homes provide a better alternative to institutions may not be correct in a resource poor community and needs to be examined further.</p

Attitudes Towards End-of-Life Decisions and the Subjective Concepts of Consciousness: An Empirical Analysis

Background: People have fought for their civil rights, primarily the right to live in dignity. At present, the development of technology in medicine and healthcare led to an apparent paradox: many people are fighting for the right to die. This study was aimed at testing whether different moral principles are associated with different attitudes towards end-of-life decisions for patients with a severe brain damage. Methodology: We focused on the ethical decisions about withdrawing life-sustaining treatments in patients with severe brain damage. 202 undergraduate students at the University of Padova were given one description drawn from four profiles describing different pathological states: the permanent vegetative state, the minimally conscious state, the locked-in syndrome, and the terminal illness. Participants were asked to evaluate how dead or how alive the patient was, and how appropriate it was to satisfy the patient's desire. Principal Findings: We found that the moral principles in which people believe affect not only people's judgments concerning the appropriateness of the withdrawal of life support, but also the perception of the death status of patients with severe brain injury. In particular, we found that the supporters of the Free Choice (FC) principle perceived the death status of the patients with different pathologies differently: the more people believe in the FC, the more they perceived patients as dead in pathologies where conscious awareness is severely impaired. By contrast, participants who agree with the Sanctity of Life (SL) principle did not show differences across pathologies. Conclusions: These results may shed light on the complex aspects of moral consensus for supporting or rejecting end-of-life decisions

Ethnic differences in mental health among incarcerated youths: do Moroccan immigrant boys show less psychopathology than native Dutch boys?

Psychiatric disorders are highly prevalent among incarcerated youth. However, whereas ethnic minority youths are overrepresented in the juvenile justice system, limited research is available on their mental health. In this study, differences in mental health problems between incarcerated adolescents of native Dutch and Moroccan origin, were examined. Child Behavior Checklist and Youth Self-Report scores were compared between incarcerated adolescents of native Dutch and Moroccan origin. Their scores were also compared to those of native Dutch and Moroccan immigrant youths in the general, non-incarcerated population. Native Dutch incarcerated adolescents showed higher levels of various mental health problems than incarcerated adolescents with a Moroccan background. Compared to the general population, incarcerated youths showed higher levels of mental health problems, but this deviation was much larger for native Dutch than for Moroccan immigrant youths. These ethnic differences in mental health problems could not be explained by ethnic differences in socio-economic background and social desirable answering tendencies. Incarcerated youths of Moroccan origin show less psychopathology than incarcerated native Dutch youths, which might be explained by disparities in sentencing procedures