Gallium Nitride Super-Luminescent Light Emitting Diodes for Optical Coherence Tomography Applications

The role of biasing of absorber sections in multi-contact GaN ~400nm SLEDs is discussed. We go on to assess such devices for OCT applications. Analysis of the SLED emission spectrum allows an axial resolution of 6.0μm to be deduced in OCT applications

Speech Communication

Contains research objectives and reports on three research projects.U. S. Air Force (Electronics Systems Division) under Contract AF 19(628)-5661National Institutes of Health (Grant 2 RO1 NB-04332-06)Joint Services Electronics Programs (U. S. Army, U.S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E

Gallium nitride light sources for optical coherence tomography

The advent of optical coherence tomography (OCT) has permitted high-resolution, non-invasive, in vivo imaging of the eye, skin and other biological tissue. The axial resolution is limited by source bandwidth and central wavelength. With the growing demand for short wavelength imaging, super-continuum sources and non-linear fibre-based light sources have been demonstrated in tissue imaging applications exploiting the near-UV and visible spectrum. Whilst the potential has been identified of using gallium nitride devices due to relative maturity of laser technology, there have been limited reports on using such low cost, robust devices in imaging systems. A GaN super-luminescent light emitting diode (SLED) was first reported in 2009, using tilted facets to suppress lasing, with the focus since on high power, low speckle and relatively low bandwidth applications. In this paper we discuss a method of producing a GaN based broadband source, including a passive absorber to suppress lasing. The merits of this passive absorber are then discussed with regards to broad-bandwidth applications, rather than power applications. For the first time in GaN devices, the performance of the light sources developed are assessed though the point spread function (PSF) (which describes an imaging systems response to a point source), calculated from the emission spectra. We show a sub-7μm resolution is possible without the use of special epitaxial techniques, ultimately outlining the suitability of these short wavelength, broadband, GaN devices for use in OCT application

Pass-through core measurements of magnetic susceptibility and natural gamma ray, New Jersey Coastal Plain

We measured magnetic susceptibility (MS) and core gamma radiation (CGR) on 3162 ft (963.9 m) of core recovered by the New Jersey Coastal Plain Drilling Project (Ocean Drilling Program Leg 150X) at Island Beach, Atlantic City, and Cape May, New Jersey. Integration of core lithology, core/log (MS and CGR), and downhole gamma-ray (DGR) log studies have (1) documented the core/log expression of previously determined unconformities; (2) shown that MS is a proxy for glauconite percent in the New Jersey Coastal Plain; (3) illustrated a major change in sedimentation from shelfal glauconite evidenced by very high MS values to deltaic deposition with low MS values in the earliest Miocene (ca. 22 Ma); (4) shown that comparison of MS and CGR with DGR can be used to resolve discrepancies in depth between downhole logs and cores; and (5) shown that the CGR detects some zones noted in the lithology (e.g., phosphate rich zones) that are not resolved in the DGR

Proteasome inhibition, the pursuit of new cancer therapeutics, and the adaptor molecule p130Cas

Current interest in proteasome inhibitors for cancer therapy has stimulated considerable research efforts to identify the molecular pathway to their cytotoxicity with a view to identifying the mechanisms of sensitivity and resistance as well as informing the development of new drugs. Zhao and Vuori describe this month in BMC Biology experiments indicating a novel role of the adaptor protein p130Cas in sensitivity to apoptosis induced not only by proteasome inhibitors but also by the unrelated drug doxorubicin

Determining the critical size of EUV mask substrate defects

Determining the printability of substrate defects beneath the extreme ultraviolet (EUV) reflecting multilayer stack is an important issue in EUVL lithography. Several simulation studies have been performed in the past to determine the tolerable defect size on EUV mask blank substrates but the industry still has no exact specification based on real printability tests. Therefore, it is imperative to experimentally determine the printability of small defects on a mask blanks that are caused by substrate defects using direct printing of programmed substrate defect in an EUV exposure tools. SEMATECH fabricated bump type program defect masks using standard electron beam lithography and performed printing tests with the masks using an EUV exposure tool. Defect images were also captured using SEMATECH's Berkeley Actinic Imaging Tool in order to compare aerial defect images with secondary electron microscope images from exposed wafers. In this paper, a comprehensive understanding of substrate defect printability will be presented and printability specifications of EUV mask substrate defects will be discussed

Geographic Differences in Time to Culture Conversion in Liquid Media: Tuberculosis Trials Consortium Study 28. Culture Conversion Is Delayed in Africa

Tuberculosis Trials Consortium Study 28, was a double blind, randomized, placebo-controlled, phase 2 clinical trial examining smear positive pulmonary Mycobacterium tuberculosis. Over the course of intensive phase therapy, patients from African sites had substantially delayed and lower rates of culture conversion to negative in liquid media compared to non-African patients. We explored potential explanations of this finding.In TBTC Study 28, protocol-correct patients (n = 328) provided spot sputum specimens for M. tuberculosis culture in liquid media, at baseline and weeks 2, 4, 6 and 8 of study therapy. We compared sputum culture conversion for African and non-African patients stratified by four baseline measures of disease severity: AFB smear quantification, extent of disease on chest radiograph, cavity size and the number of days to detection of M. tuberculosis in liquid media using the Kaplan-Meier product-limit method. We evaluated specimen processing and culture procedures used at 29 study laboratories serving 27 sites.African TB patients had more extensive disease at enrollment than non-African patients. However, African patients with the least disease by the 4 measures of disease severity had conversion rates on liquid media that were substantially lower than conversion rates in non-African patients with the greatest extent of disease. HIV infection, smoking and diabetes did not explain delayed conversion in Africa. Some inter-site variation in laboratory processing and culture procedures within accepted practice for clinical diagnostic laboratories was found.Compared with patients from non-African sites, African patients being treated for TB had delayed sputum culture conversion and lower sputum conversion rates in liquid media that were not explained by baseline severity of disease, HIV status, age, smoking, diabetes or race. Further investigation is warranted into whether modest variation in laboratory processes substantially influences the efficacy outcomes of phase 2 TB treatment trials or if other factors (e.g., nutrition, host response) are involved.ClinicalTrials.gov NCT00144417

Increased incidence of hypothyroidism in primary biliary cirrhosis

We examined the thyroid status of 58 patients with primary biliary cirrhosis (PBC) using total serum thyroxin, thyroid hormone binding ratio, free thyroxin index, serum TSH, antithyroglobulin, and antimicrosomal antibodies. Seven patients were known to be hypothyroid prior to the diagnosis of PBC. Six additional patients were found to have biochemical evidence of hypothyroidism. The prevalence of hypothyroidism was 12% if we include only those six PBC patients with newly diagnosed hypothyroidism or 22% if we include all 13 patients. Five of the 58 patients had evidence for an elevation of thyroid hormone binding capacity. Three hypothyroid patients had normal total thyroxins with low thyroid hormone binding ratios. Two euthyroid patients had elevated total T 4 s with low thyroid hormone binding ratio and normal FTI. The prevalence of positive antimicrosomal antibodies was 34%, including 11 euthyroid PBC patients. The prevalence of positive antithyroglobulin antibodies was 20% including five euthyroid patients. There was no association between HLA DR3 or DR5 and the patients with hypothyroidism and/ or antithyroid antibodies. Because fatigue, lethargy, and anorexia as well as hypercholesterolemia are common features of both hypothyroidism and PBC, patients with PBC should be screened for evidence of thyroid dysfunction. Thyroid disease may precede the diagnosis of PBC by several years. Therefore, the development of cholestatic liver disease in a patient with known autoimmune thyroiditis should arouse suspicion of PBC.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44393/1/10620_2005_Article_BF01311724.pd

Determining the Critcial Size of EUV Mask Substrate Defects

Determining the printability of substrate defects beneath the extreme ultraviolet (EUV) reflecting multilayer stack is an important issue in EUVL lithography. Several simulation studies have been performed in the past to determine the tolerable defect size on EUV mask blank substrates but the industry still has no exact specification based on real printability tests. Therefore, it is imperative to experimentally determine the printability of small defects on a mask blanks that are caused by substrate defects using direct printing of programmed substrate defect in an EUV exposure tool. SEMATECH fabricated bump type program defect masks using standard electron beam lithography and performed printing tests with the masks using an EUV exposure tool. Defect images were also captured using SEMATECH's Berkeley Actinic Imaging Tool in order to compare aerial defect images with secondary electron microscope images from exposed wafers. In this paper, a comprehensive understanding of substrate defect printability will be presented and printability specifications of EUV mask substrate defects will be discussed