Laser pulse annealing of ion-implanted GaAs

GaAs single-crystals wafers are implanted at room temperature with 400-keV Te + ions to a dose of 1×10^15 cm^–2 to form an amorphous surface layer. The recrystallization of this layer is investigated by backscattering spectrometry and transmission electron microscopy after transient annealing by Q-switched ruby laser irradiation. An energy density threshold of about 1.0 J/cm^2 exists above which the layer regrows epitaxially. Below the threshold the layer is polycrystalline; the grain size increases as the energy density approaches threshold. The results are analogous to those reported for the elemental semiconductors, Si and Ge. The threshold value observed is in good agreement with that predicted by the simple model successfully applied previously to Si and Ge

PhylOTU: a high-throughput procedure quantifies microbial community diversity and resolves novel taxa from metagenomic data.

Microbial diversity is typically characterized by clustering ribosomal RNA (SSU-rRNA) sequences into operational taxonomic units (OTUs). Targeted sequencing of environmental SSU-rRNA markers via PCR may fail to detect OTUs due to biases in priming and amplification. Analysis of shotgun sequenced environmental DNA, known as metagenomics, avoids amplification bias but generates fragmentary, non-overlapping sequence reads that cannot be clustered by existing OTU-finding methods. To circumvent these limitations, we developed PhylOTU, a computational workflow that identifies OTUs from metagenomic SSU-rRNA sequence data through the use of phylogenetic principles and probabilistic sequence profiles. Using simulated metagenomic data, we quantified the accuracy with which PhylOTU clusters reads into OTUs. Comparisons of PCR and shotgun sequenced SSU-rRNA markers derived from the global open ocean revealed that while PCR libraries identify more OTUs per sequenced residue, metagenomic libraries recover a greater taxonomic diversity of OTUs. In addition, we discover novel species, genera and families in the metagenomic libraries, including OTUs from phyla missed by analysis of PCR sequences. Taken together, these results suggest that PhylOTU enables characterization of part of the biosphere currently hidden from PCR-based surveys of diversity

Modeling the Geographic Distribution of \u3ci\u3eIxodes scapularis\u3c/i\u3e and \u3ci\u3eIxodes pacificus\u3c/i\u3e (Acari: Ixodidae) in the Contiguous United States

In addition to serving as vectors of several other human pathogens, the black-legged tick, Ixodes scapularis Say, and western black-legged tick, Ixodes pacificus Cooley and Kohls, are the primary vectors of the spirochete (Borrelia burgdorferi) that causes Lyme disease, the most common vector-borne disease in the United States. Over the past two decades, the geographic range of I. pacificus has changed modestly while, in contrast, the I. scapularis range has expanded substantially, which likely contributes to the concurrent expansion in the distribution of human Lyme disease cases in the Northeastern, North-Central and Mid-Atlantic states. Identifying counties that contain suitable habitat for these ticks that have not yet reported established vector populations can aid in targeting limited vector surveillance resources to areas where tick invasion and potential human risk are likely to occur. We used county-level vector distribution information and ensemble modeling to map the potential distribution of I. scapularis and I. pacificus in the contiguous United States as a function of climate, elevation, and forest cover. Results show that I. pacificus is currently present within much of the range classified by our model as suitable for establishment. In contrast, environmental conditions are suitable for I. scapularis to continue expanding its range into northwestern Minnesota, central and northern Michigan, within the Ohio River Valley, and inland from the southeastern and Gulf coasts. Overall, our ensemble models show suitable habitat for I. scapularis in 441 eastern counties and for I. pacificus in 11 western counties where surveillance records have not yet supported classification of the counties as established

Description and evaluation of a pathway for unaccompanied asylum-seeking children

Objective: (1) To describe a novel integrated pathway for unaccompanied asylum-seeking children (UASC). (2) To evaluate a population engaged with this service. Design: Description of the integrated pathway (objective 1) and retrospective evaluation, using data from community paediatrics, infectious diseases (IDs) screening and a sexual health (SH) service (objective 2). Setting: Unlinked data were collected from three services across three National Health Service (NHS) trusts in London. Patients: All Camden UASC engaged with the service from 01 January 2016 to 30 March 2019. Interventions: A multidisciplinary approach prioritising the health needs of UASC including a childre and adolescent mental health service (CAMHS) clinican and a health improvement practitioner. There are low thresholds for onward referral and universal asymptomatic screening of UASC for ID. Main outcome measures: Data on demographics, unmet health needs and known outcomes. Results: Data were available for 101 UASC, 16% female, median age 16 years (range 14–17). Physical assault/abuse was reported in 67% and 13% disclosed sexual assault/abuse, including 38% of female UASC. Mental health symptoms were documented in 77%. IDs warranting treatment were identified in 41% including latent tuberculosis (25%) and schistosomiasis (13%). Interpreters were required for 97% and initial non-attendance rates at follow-up were 40% (ID) and 49% (SH). Conclusions: These data demonstrate high rates of historical physical and sexual assault/abuse, unmet physical, mental and emotional health needs among UASC and significant barriers to engaging with services. An integrated pathway has been successfully implemented and shown to deliver appropriate, joined-up care for UASC, consistent with current recommendations, with the potential to improve outcomes

Comparative genomics and understanding of microbial biology.

The sequences of close to 30 microbial genomes have been completed during the past 5 years, and the sequences of more than 100 genomes should be completed in the next 2 to 4 years. Soon, completed microbial genome sequences will represent a collection of >200,000 predicted coding sequences. While analysis of a single genome provides tremendous biological insights on any given organism, comparative analysis of multiple genomes provides substantially more information on the physiology and evolution of microbial species and expands our ability to better assign putative function to predicted coding sequences