Effects of a nonlinear perturbation on dynamical tunneling in cold atoms

We perform a numerical analysis of the effects of a nonlinear perturbation on the quantum dynamics of two models describing non-interacting cold atoms in a standing wave of light with a periodical modulated amplitude $A(t)$. One model is the driven pendulum, considered in ref.\cite{raiz1}, and the other is a variant of the well-known Kicked Rotator Model. In absence of the nonlinear perturbation, the system is invariant under some discrete symmetries and quantum dynamical tunnelling between symmetric classical islands is found. The presence of nonlinearity destroys tunnelling, breaking the symmetries of the system. Finally, further consequences of nonlinearity in the kicked rotator case are considered.Comment: 10 pages, 15 figure

Thermal and Sedimentation Stress Are Unlikely Causes of Brown Spot Syndrome in the Coral Reef Sponge, Ianthella basta

Background: Marine diseases are being increasingly linked to anthropogenic factors including global and local stressors. On the Great Barrier Reef, up to 66% of the Ianthella basta population was recently found to be afflicted by a syndrome characterized by brown spot lesions and necrotic tissue.\ud \ud Methodology/Principal Findings: Manipulative experiments were undertaken to ascertain the role of environmental stressors in this syndrome. Specifically, the effects of elevated temperature and sedimentation on sponge health and symbiont stability in I. basta were examined. Neither elevated temperature nor increased sedimentation were responsible for the brown spot lesions, but sponges exposed to 32°C developed substantial discoloration and deterioration of their tissues, resulting in death after eight days and a higher microbial diversity in those samples. No shifts in the microbial community of I. basta were observed across a latitudinal gradient or with increased sedimentation, with three previously described symbionts dominating the community of all sponges (Alphaproteobacteria, Gammaproteobacteria and Thaumarchaea).\ud \ud Conclusions/Significance: Results from this study highlight the stable microbial community of I. basta and indicate that thermal and sedimentation stress are not responsible for the brown spot lesions currently affecting this abundant and ecologically important sponge species

The Dose Response: Perceptions of People Living with HIV in the United States on Alternatives to Oral Daily Antiretroviral Therapy

There are two concurrent and novel major research pathways toward strategies for HIV control: (1) long-acting antiretroviral therapy (ART) formulations and (2) research aimed at conferring sustained ART-free HIV remission, considered a step toward an HIV cure. The importance of perspectives from people living with HIV on the development of new modalities is high, but data are lacking. We administered an online survey in which respondents selected their likelihood of participation or nonparticipation in HIV cure/remission research based on potential risks and perceived benefits of these new modalities. We also tested the correlation between perceptions of potential risks and benefits with preferences of virologic control strategies and/or responses to scenario choices, while controlling for respondent characteristics. Of the 282 eligible respondents, 42% would be willing to switch from oral daily ART to long-acting ART injectables or implantables taken at 6-month intervals, and 24% to a hypothetical ART-free remission strategy. We found statistically significant gender differences in perceptions of risk and preferences of HIV control strategies, and possible psychosocial factors that could mediate willingness to switch to novel HIV treatment or remission options. Our study yielded data on possible desirable product characteristics for future HIV treatment and remission options. Findings also revealed differences in motivations and preferences across gender and other sociodemographic characteristics that may be actionable as part of research recruitment efforts. The diversity of participant perspectives reveals the need to provide a variety of therapeutic options to people living with HIV and to acknowledge their diverse experiential expertise when developing novel HIV therapies

Biochemical Trade-Offs: Evidence for Ecologically Linked Secondary Metabolism of the Sponge Oscarella balibaloi

Secondary metabolite production is assumed to be costly and therefore the resource allocation to their production should be optimized with respect to primary biological functions such as growth or reproduction. Sponges are known to produce a great diversity of secondary metabolites with powerful biological activities that may explain their domination in some hard substrate communities both in terms of diversity and biomass. Oscarella balibaloi (Homoscleromorpha) is a recently described, highly dynamic species, which often overgrows other sessile marine invertebrates. Bioactivity measurements (standardized Microtox assay) and metabolic fingerprints were used as indicators of the baseline variations of the O. balibaloi secondary metabolism, and related to the sponge reproductive effort over two years. The bioactivity showed a significant seasonal variation with the lowest values at the end of spring and in early summer followed by the highest bioactivity in the late summer and autumn. An effect of the seawater temperature was detected, with a significantly higher bioactivity in warm conditions. There was also a tendency of a higher bioactivity when O. balibaloi was found overgrowing other sponge species. Metabolic fingerprints revealed the existence of three principal metabolic phenotypes: phenotype 1 exhibited by a majority of low bioactive, female individuals, whereas phenotypes 2 and 3 correspond to a majority of highly bioactive, non-reproductive individuals. The bioactivity was negatively correlated to the reproductive effort, minimal bioactivities coinciding with the period of embryogenesis and larval development. Our results fit the Optimal Defense Theory with an investment in the reproduction mainly shaping the secondary metabolism variability, and a less pronounced influence of other biotic (species interaction) and abiotic (temperature) factors

Viral ecogenomics across the Porifera

BackgroundViruses directly affect the most important biological processes in the ocean via their regulation of prokaryotic and eukaryotic populations. Marine sponges form stable symbiotic partnerships with a wide diversity of microorganisms and this high symbiont complexity makes them an ideal model for studying viral ecology. Here, we used morphological and molecular approaches to illuminate the diversity and function of viruses inhabiting nine sponge species from the Great Barrier Reef and seven from the Red Sea.ResultsViromic sequencing revealed host-specific and site-specific patterns in the viral assemblages, with all sponge species dominated by the bacteriophage order Caudovirales but also containing variable representation from the nucleocytoplasmic large DNA virus families Mimiviridae, Marseilleviridae, Phycodnaviridae, Ascoviridae, Iridoviridae, Asfarviridae and Poxviridae. Whilst core viral functions related to replication, infection and structure were largely consistent across the sponge viromes, functional profiles varied significantly between species and sites largely due to differential representation of putative auxiliary metabolic genes (AMGs) and accessory genes, including those associated with herbicide resistance, heavy metal resistance and nylon degradation. Furthermore, putative AMGs varied with the composition and abundance of the sponge-associated microbiome. For instance, genes associated with antimicrobial activity were enriched in low microbial abundance sponges, genes associated with nitrogen metabolism were enriched in high microbial abundance sponges and genes related to cellulose biosynthesis were enriched in species that host photosynthetic symbionts.ConclusionsOur results highlight the diverse functional roles that viruses can play in marine sponges and are consistent with our current understanding of sponge ecology. Differential representation of putative viral AMGs and accessory genes across sponge species illustrate the diverse suite of beneficial roles viruses can play in the functional ecology of these complex reef holobionts

Modularity and predicted functions of the global sponge-microbiome network

Defining the organisation of species interaction networks and unveiling the processes behind their assembly is fundamental to understanding patterns of biodiversity, community stability and ecosystem functioning. Marine sponges host complex communities of microorganisms that contribute to their health and survival, yet the mechanisms behind microbiome assembly are largely unknown. We present the global marine sponge-microbiome network and reveal a modular organisation in both community structure and function. Modules are linked by a few sponge species that share microbes with other species around the world. Further, we provide evidence that abiotic factors influence the structuring of the sponge microbiome when considering all microbes present, but biotic interactions drive the assembly of more intimately associated 'core' microorganisms. These findings suggest that both ecological and evolutionary processes are at play in host-microbe network assembly. We expect mechanisms behind microbiome assembly to be consistent across multicellular hosts throughout the tree of life

Critical Consciousness and Schooling: The Impact of the Community as a Classroom Program on Academic Indicators

The present study investigates the extent to which a program guided by the principles of critical pedagogy, which seeks to develop critical consciousness, is associated with the improved academic performance of students attending a low-performance middle-school in Buffalo, New York. The students were enrolled in an in-school academic support program called the Community as Classroom, which used critical project-based learning to show students how to improve neighborhood conditions. The study found that the Community as Classroom program bolstered student engagement as reflected in improved attendance, on-time-arrival at school, and reduced suspensions. Although class grades did not improve, standardized scores, particularly in Math and Science, dramatically improved for these students from the lowest scoring categories. We suspect that given increased student engagement and dramatically improved standardized test scores, teacher bias might be the cause of no improvements in class grades. We conclude that critical pedagogy, which leads to increased critical consciousness, is a tool that can lead to improved academic performance of students. Such a pedagogy, we argue, should be more widely used in public schools, with a particular emphasis on their deployment in Community Schools

The University, Neighborhood Revitalization, and Civic Engagement: Toward Civic Engagement 3.0

This essay analyzes and syntheses key theories and concepts on neighborhood change from the literature on anchor institutions, university engagement, gentrification, neighborhood effects, Cold War, Black liberation studies, urban political economy, and city building. To deepen understanding of the Columbia University experience, we complemented the literature analysis with an examination of the New York Times and Amsterdam newspapers from 1950 to 1970. The study argues that higher education’s approach to neighborhood revitalization during the urban renewal age, as well as in the post-1990 period, produced undesirable results and failed to spawn either social transformation or build the neighborly community espoused by Lee Benson and Ira Harkavy. The essay explains the reasons why and concludes with a section on a more robust strategy higher education can pursue in the quest to bring about desirable change in the university neighborhood