1,470 research outputs found
Distorted wurtzite unit cells: Determination of lattice parameters of non-polar a-plane AlGaN and estimation of solid phase Al content
Unlike c-plane nitrides, ``non-polar" nitrides grown in e.g. the a-plane or
m-plane orientation encounter anisotropic in-plane strain due to the anisotropy
in the lattice and thermal mismatch with the substrate or buffer layer. Such
anisotropic strain results in a distortion of the wurtzite unit cell and
creates difficulty in accurate determination of lattice parameters and solid
phase group-III content (x_solid) in ternary alloys. In this paper we show that
the lattice distortion is orthorhombic, and outline a relatively simple
procedure for measurement of lattice parameters of non-polar group III-nitrides
epilayers from high resolution x-ray diffraction measurements. We derive an
approximate expression for x_solid taking into account the anisotropic strain.
We illustrate this using data for a-plane AlGaN, where we measure the lattice
parameters and estimate the solid phase Al content, and also show that this
method is applicable for m-plane structures as well
Language Classification using N-grams Accelerated by FPGA-based Bloom Filters
N-Gram (n-character sequences in text documents) counting is a well-established technique used in classifying the language of text in a document. In this paper, n-gram processing is accelerated through the use of reconfigurable hardware on the XtremeData XD1000 system. Our design employs parallelism at multiple levels, with parallel Bloom Filters accessing on-chip RAM, parallel language classifiers, and parallel document processing. In contrast to another hardware implementation (HAIL algorithm) that uses off-chip SRAM for lookup, our highly scalable implementation uses only on-chip memory blocks. Our implementation of end-to-end language classification runs at 85x comparable software and 1.45x the competing hardware design
Interpretations arising from Wrightian and Malthusian fitness under strong frequency dependent selection
A rare case of synovial sarcoma of the prostate
Prostatic synovial sarcomas are exceedingly rare. To our knowledge, only six primary cases have been reported so far. We herein describe a primary synovial sarcoma of the prostate seen in a 25- year-old male patient, the youngest patient seen with this disease to date. He was referred to our department with the diagnosis of high-grade sarcoma of the prostate revealed by TRUS-guided biopsy. On admission he had a transurethral catheter for acute retention of urine. MRI revealed a solid prostatic tumor of 9.5 x 8 cm involving the rectum without any evidence of lymphatic or distant metastases. The patient underwent total pelvic exenteration and sigmoid end colostomy with ileal conduit. Histopathology revealed a synovial sarcoma of the prostate, immunoreactive to vimentin, Bcl–2 and cytokeratin. The patient is doing well at 18 months follow-up.Key Words: Prostatic sarcoma, prostatic malignancy, prostate, synovial sarcom
Dipeptidyl-peptidase-4 inhibitors and pancreatic cancer: a cohort study
Aims—Dipeptidyl-peptidase-4 inhibitors (DPP-4i) have been implicated with an increased pancreatic cancer risk. We therefore compared pancreatic cancer incidence and diagnostic work-up among initiators of DPP-4i versus sulfonylureas (SU) and thiazolidinediones (TZD). Methods—Medicare claims data were examined in a new-user active-comparator cohort study. Patients >65 years with no prescriptions for DPP-4i, SU or TZD at baseline were included if they had at least two claims for the same drug within 180 days. Using an as-treated approach and propensity score-adjusted Cox models, we estimated hazard ratios (HR) and 95% confidence intervals (CI) for pancreatic cancer. Diagnostic work-up was compared using risk ratios (RR). RESULTS—In the DPP-4i vs SU comparison, there were 18,179 DPP4i initiators of which 26 developed pancreatic cancer (follow-up time interquartile range 5–18 months). In the DPP-4i vs TZD comparison there were 29,366 DPP-4i initiators and 52 developed pancreatic cancer. The hazard of pancreatic cancer with DPP-4i was lower relative to SU (HR=0.6, CI 0.4–0.9) and similar to TZD (HR=1.0, CI 0.7–1.4). Excluding first 6 months of follow-up to reduce the potential for reverse causality did not alter results. Probability of diagnostic work-up post-initiation among DPP-4i initiators (79.3%) was similar to TZD (74.1%) (RR=1.06, CI 1.05–1.07) and SU (74.6%) (RR=1.06, CI1.05–1.07). The probability of diagnostic workup pre-index was ~80% for all cohorts. Conclusion—Though limited by sample size and the observed duration of treatment in the US, our well-controlled population based study suggests no increased short-term pancreatic cancer risk with DPP-4i relative to SU or TZD
Stochastic slowdown in evolutionary processes
We examine birth--death processes with state dependent transition
probabilities and at least one absorbing boundary. In evolution, this describes
selection acting on two different types in a finite population where
reproductive events occur successively. If the two types have equal fitness the
system performs a random walk. If one type has a fitness advantage it is
favored by selection, which introduces a bias (asymmetry) in the transition
probabilities. How long does it take until advantageous mutants have invaded
and taken over? Surprisingly, we find that the average time of such a process
can increase, even if the mutant type always has a fitness advantage. We
discuss this finding for the Moran process and develop a simplified model which
allows a more intuitive understanding. We show that this effect can occur for
weak but non--vanishing bias (selection) in the state dependent transition
rates and infer the scaling with system size. We also address the Wright-Fisher
model commonly used in population genetics, which shows that this stochastic
slowdown is not restricted to birth-death processes.Comment: 8 pages, 3 figures, accepted for publicatio
On the interpretation of spin-polarized electron energy loss spectra
We study the origin of the structure in the spin-polarized electron energy
loss spectroscopy (SPEELS) spectra of ferromagnetic crystals. Our study is
based on a 3d tight-binding Fe model, with constant onsite Coulomb repulsion U
between electrons of opposite spin. We find it is not the total density of
Stoner states as a function of energy loss which determines the response of the
system in the Stoner region, as usually thought, but the densities of Stoner
states for only a few interband transitions. Which transitions are important
depends ultimately on how strongly umklapp processes couple the corresponding
bands. This allows us to show, in particular, that the Stoner peak in SPEELS
spectra does not necessarily indicate the value of the exchange splitting
energy. Thus, the common assumption that this peak allows us to estimate the
magnetic moment through its correlation with exchange splitting should be
reconsidered, both in bulk and surface studies. Furthermore, we are able to
show that the above mechanism is one of the main causes for the typical
broadness of experimental spectra. Finally, our model predicts that optical
spin waves should be excited in SPEELS experiments.Comment: 11 pages, 7 eps figures, REVTeX fil
Efficacy of Pluronic F-127 gel containing green tea catechin extract on chronic periodontitis – A clinical study
Purpose: To evaluate the efficacy of pluronic F-127 gel containing green tea catechin extract as a local drug delivery system in the treatment of chronic periodontitis.
Methods: A total of 20 chronic periodontitis patients participated as per the set inclusion and exclusion criteria. Complete scaling and root planing (SRP) was done for all subjects and pluronic F-127 gel containing green tea catechin was applied on one site. The contralateral site received SRP alone. The plaque index (PI), gingival index (GI), and probing pocket depth (PPD) were recorded at baseline and on the 28th day.
Results: At the 28th-day follow-up, green tea catechin tooth sites showed significantly lower mean scores (GI = 0.55, p = 0.30 and PPD = 3.35 mm) than the corresponding SRP tooth sites (GI = 1.25, PI = 1.15, and PPD = 4.40 mm) (p < 0.05).
Conclusion: When compared to scaling and root planing alone, the local drug delivery gel containing green tea catechin as an adjuvant was more effective in reducing the clinical parameters of periodontitis.
Keywords: Adjuvant therapy, Camellia sinensis, Local drug delivery, Periodontal pocke
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