Breaking the Buildup-time Limit of sensitivity in Avalanche Photodiodes by Dynamic Biasing

Avalanche photodiodes (APDs) are the preferred photodetectors for direct-detection, high data-rate long-haul optical telecommunications. APDs can detect low-level optical signals due to their internal amplification of the photon-generated electrical current, which is attributable to the avalanche of electron and hole impact ionizations. Despite recent advances in APDs aimed at reducing the average avalanche-buildup time, which causes intersymbol interference and compromises receiver sensitivity at high data rates, operable speeds of commercially available APDs have been limited to 10Gbps. We report the first demonstration of a dynamically biased APD that breaks the traditional sensitivity-versus-speed limit by employing a data-synchronous sinusoidal reverse-bias that drastically suppresses the average avalanche-buildup time. Compared with traditional DC biasing, the sensitivity of germanium APDs at 3Gbps is improved by 4.3 dB, which is equivalent to a 3,500-fold reduction in the bit-error rate. The method is APD-type agnostic and it promises to enable operation at rates of 25Gbps and beyond

High-Performance Multi-Mode Ptychography Reconstruction on Distributed GPUs

Ptychography is an emerging imaging technique that is able to provide wavelength-limited spatial resolution from specimen with extended lateral dimensions. As a scanning microscopy method, a typical two-dimensional image requires a number of data frames. As a diffraction-based imaging technique, the real-space image has to be recovered through iterative reconstruction algorithms. Due to these two inherent aspects, a ptychographic reconstruction is generally a computation-intensive and time-consuming process, which limits the throughput of this method. We report an accelerated version of the multi-mode difference map algorithm for ptychography reconstruction using multiple distributed GPUs. This approach leverages available scientific computing packages in Python, including mpi4py and PyCUDA, with the core computation functions implemented in CUDA C. We find that interestingly even with MPI collective communications, the weak scaling in the number of GPU nodes can still remain nearly constant. Most importantly, for realistic diffraction measurements, we observe a speedup ranging from a factor of $10$ to $10^3$ depending on the data size, which reduces the reconstruction time remarkably from hours to typically about 1 minute and is thus critical for real-time data processing and visualization.Comment: work presented in NYSDS 201

Visual representation of National Institute of Allergy and Infectious Disease and Food Allergy and Anaphylaxis Network criteria for anaphylaxis

We present a user-friendly visual representation of The National Institute of Allergy and Infectious Disease and the Food Allergy and Anaphylaxis Network criteria so as to enhance recognition of anaphylaxis and active teaching and learning

FTIR autecological analysis of bottom-ice diatom taxa across a tidal strait in the Canadian Arctic

A recent study demonstrated that an Arctic tidal strait, where a shoaled and constricted waterway increases tidally driven sub-ice currents and turbulence, represents a “hotspot” for ice algal production due to a hypothesized enhanced ocean-ice nutrient supply. Based on these findings, we sampled the bottom-ice algal community across the same tidal strait between the Finlayson Islands within Dease Strait, Nunavut, Canada, in spring 2017. Our objective was to examine cellular responses of sea-ice diatoms to two expected nutrient supply gradients in their natural environment: (1) a horizontal gradient across the tidal strait and (2) a vertical gradient in the bottom-ice matrix. Two diatom taxa, Nitzschia frigida and Attheya spp. in bottomice sections (0–2, 2–5, and 5–10 cm) under thin snow cover (<5 cm), were selected for Fourier Transform Infrared (FTIR) spectrochemical analysis for lipid and protein content. Results from the FTIR technique strongly supported the existence of a horizontal nutrient gradient across the tidal strait of the Finlayson Islands, while estimates of particulate organic carbon and chlorophyll a concentrations were difficult to interpret. The larger N. frigida cells appeared to be more sensitive to the suspected horizontal nutrient gradient, significantly increasing in lipid content relative to protein beyond the tidal strait. In contrast, the epiphytic diatoms, Attheya spp., were more sensitive to the vertical gradient: above 2 cm in the bottom-ice matrix, the non-motile cells appeared to be trapped with a depleted nutrient inventory and evidence of a post-bloom state. Application of the FTIR technique to estimate biomolecular composition of algal cells provided new insights on the response of the bottom-ice algal community to the examined spatial gradients that could not be obtained from conventional bulk measurements alone. Future studies of sea ice and associated environments are thus encouraged to employ this technique

B cell receptor accessory molecule CD79α : characterisation and expression analysis in a cartilaginous fish, the spiny dogfish (Squalus acanthias)

Copyright © 2013. Published by Elsevier Ltd.Peer reviewedPublisher PD

Effect of Body Mass Index on pregnancy outcomes in nulliparous women delivering singleton babies

Peer reviewedPublisher PD

Incidence of fracture in adjacent levels in patients treated with balloon kyphoplasty: a review of the literature

The available evidence suggests that the treatment of painful vertebral compression fractures (VCFs) secondary to osteoporosis or multiple myeloma, by cement augmentation with balloon kyphoplasty (BK), is both safe and effective. However, there is uncertainty in the literature concerning the potential of the procedure to influence the risk for adjacent segment fracture. The aim of this article is to review the available peer-reviewed literature, regarding adjacent vertebral body fractures after kyphoplasty augmentation

Choosing sensitivity analyses for randomised trials: principles

Background Sensitivity analyses are an important tool for understanding the extent to which the results of randomised trials depend upon the assumptions of the analysis. There is currently no guidance governing the choice of sensitivity analyses. Discussion We provide a principled approach to choosing sensitivity analyses through the consideration of the following questions: 1) Does the proposed sensitivity analysis address the same question as the primary analysis? 2) Is it possible for the proposed sensitivity analysis to return a different result to the primary analysis? 3) If the results do differ, is there any uncertainty as to which will be believed? Answering all of these questions in the affirmative will help researchers to identify relevant sensitivity analyses. Treating analyses as sensitivity analyses when one or more of the answers are negative can be misleading and confuse the interpretation of studies. The value of these questions is illustrated with several examples. Summary By removing unreasonable analyses that might have been performed, these questions will lead to relevant sensitivity analyses, which help to assess the robustness of trial results

A new species, *Adamsia obvolva* (Cnidaria: Anthozoa: Actiniaria), from the Gulf of Mexico, and a discussion of the taxonomy of carcinoecium-forming sea anemones

Asterisks (*...*) surround words or phrases that are to be italicized.*Adamsia obvolva* is a new species of sea anemone (order Actiniaria, family Hormathiidae) from the Gulf of Mexico, symbiotic with the hermit crab *Parapagurus pictus* (Smith, 1883). The pedal disc of the anemone enwraps the gastropod shell in which the hermit crab lives, and secretes a thin, chitinous carcinoecium that lies between the pedal disc ectoderm of the anemone and the gastropod shell. The description of *A. obvolva* n. sp. highlights many of the problems confounding the systematics of actiniarians symbiotic with hermit crabs. *Adamsia obvolva*, which has been misidentified as *Paracalliactis involvens* (McMurrich, 1893), presents a suite of attributes that blur the distinction between the genera *Adamsia* Forbes, 1840, and *Calliactis Verrill*, 1869. We review definitions of these genera and emend *Adamsia* to include only those species that form a carcinoecium and have a lobed pedal disc. To better differentiate between *A. obvolva* and *P. involvens*, we investigate the syntypes of *Adamsia involvens* McMurrich, 1893, which had been transferred to *Paracalliactis*, and of its putative synonym *Urticina consors* Verrill, 1882; we redescribe the species as *Paracalliactis consors* (Verrill, 1882). *Adamsia obvolva* and *P. consors* can be distinguished by tentacle number, the cinclides on the lower column of specimens of *A. obvolva*, and cnidae distribution and size. The taxonomic changes we propose are summarized in a diagnostic key to actiniarian families and genera that live attached to gastropod shells