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A molecular imprinted polymer, prepared around a tamoxifen template, has been synthesised. The feasibility of using this polymer for solid-phase extraction of tamoxifen from biological samples has been investigated. The results show that the drug can be quantitatively retained and eluted from the polymer using acetonitrile–acetic acid. Experiments with biological fluids indicate that clean traces are obtained for HPLC with UV detection using this type of protocol.

Optical modulators operating at near-infrared wavelengths are of interest for a variety of applications including bidirectional communications and optical interconnects. The fabrication of 1.06 {micro}m and 1.32 {micro}m operating wavelength strained-layer-superlattice vertical-cavity optoelectronic modulators requires the formation of a p-type ohmic contact to the InAlAs/InGaAs quarter-wave bottom mirror stack. In this study, BeAu and TiPtAu p-type ohmic contact metallization schemes were evaluated for use on molecular beam epitaxy (MBE) grown In{sub .10}Al{sub .90}As/In{sub .12}Ga{sub .88}As and In{sub .32}Al{sub .68}As/In{sub .33}Ga{sub .67}As device heterostructures. Recessed and nonrecessed transmission line measurement (TLM) structures were fabricated and evaluated as a function of rapid thermal anneal (RTA) temperatures over the range of 360 C--420 C. Atomic force microscopy (AFM) was used to determine the surface morphology of each sample for evidence of metal or material degradation. For contacts directly on InGaAs layers, TiPtAu contacts had relatively high specific contact resistance values of {rho}{sub c} {approximately} 3 {times} 10{sup {minus}4} {Omega}cm{sup 2} and displayed no dependence on the anneal. The BeAu contacts had minimum specific contact resistance values of {rho}{sub c} {approximately} 5 {times} 10{sup {minus}7} {Omega}cm{sup 2} but showed evidence of degradation at higher temperatures. Contacts directly made to InAlAs layers had minimum specific contact resistances of {rho}{sub c} {approximately} 4 {times} 10{sup {minus}5} {Omega}cm{sup 2} and were improved slightly with the addition of a thin GaAs layer.

Adhesion strength and surface morphology of commonly used n- and p-type ohmic contacts and pad metallization schemes for GaAs were investigated. GeNiAu, GePdAu, BeAu, and TiPtAu (being studied as potential ohmic contacts for internal optoelectronic devices) had quantitiative measurements made using wire bond pull testing to determine adhesion. Bond pad metals deposited as evaporated TiAu, TiPtAu, and 2-5 micron thick electroplated Au deposited on both semi-insulating GaAs and on Si{sub 3}N{sub 4}/GaAs were evaluated independently from the ohmic contact metals. In all samples was observed a strong correlation between surface treatment, surface morphology, wire bondability, and bond strength. Very high bond strengths (pull test average values above 6.5 grams force with 25 micron dia Au wire) wereobtained for n-type, p-type, and bond pad metals. Average values of 8.0 gram force were achieved with two-step GeAu/NiAu/TiPtAu metallization, while one-step deposition yielded poorer values. Adhesion was also monitored after aging at 250 C in air for four different times up to 60 hr by wire bond pull testing, with little degradation occurring.

SiC Schottky rectifiers with moderate breakdown voltages of ∼450 V and with either WSiX or Ni rectifying contacts were irradiated with Co-60 γ-rays to doses up to ∼315 Mrad. The Ni/SiC rectifiers show severe reaction of the contact after irradiation at the highest dose, badly degrading the forward current characteristics and increasing the on-state resistance by up to a factor of 6 after irradiation. By sharp contrast, the WSiX/SiC devices show little deterioration of the contact with the same conditions and changes in on-state resistance of

The H-Tx rat has inherited hydrocephalus with an onset in late gestation. Ventriculosubcutaneous shunts were placed in a group of hydrocephalic pups at 3-6 days after birth and in another group at 8-12 days after birth. Multislice proton magnetic resonance (MR) images were taken of shunt-treated pups at 7, 14, or 21 days and of age-matched control and untreated hydrocephalic rats and were subjected to quantitative analysis. Some rats were also imaged before surgery. The volume of the ventricles of untreated hydrocephalic pups increased linearly with age at a rate of 52 μl/day. The ventricles of shunted pups were reduced from the preshunt condition and were around 20% of age-matched hydrocephalic rats. There was no significant difference in the post-shunt volume between early and late shunt groups. The cortical mantle thickness in both groups of shunt-treated rats was significantly thicker than in untreated pups and close to that of control rats. It is concluded that shunt treatment at both ages reversed the hydrocephalus as measured from MR images, although other evidence from fixed brains suggests that normal morphology may not be achieved at the cellular level even for early shunts.

A comparison was made of specific contact resistivity and morphology of Ti/Al/Pt/WSi/Ti/Au and Ti/Al/Pt/W/Ti/Au ohmic contacts to AlGaN/GaN heterostructures relative to the standard Ti/Al/Pt/Au metallization. The W- and WSi-based contacts show comparable specific resistivities to that of the standard contact on similar layer structures, reaching minimum values of ∼10−5 Ω cm2 after annealing in the range 850–900 °C. However, the W- and WSi-based contacts exhibit much smoother surface morphologies, even after 950 °C annealing. For example, the root-mean-square roughness of the Ti/Al/Pt/WSi/Ti/Au contact annealed at 950 °C was unchanged from the as-deposited values whereas the Ti/Al/Pt/Au contact shows significant deterioration of the morphology under these conditions. The improved thermal stability of the W- and WSix-based contacts is important for maintaining edge acuity during high-temperature operation.

Motivated by recent interventions by the states of New Jersey and Maryland and the introduction of PJM’s Minimum Offer Price Rule (MOPR) for capacity markets, we analyze the impact of subsidized government investments in electrical generation on electricity markets. We extend the model of Joskow and Tirole (2007) to address the interconnected nature of the PJM grid by considering a market with two different locations connected by transmission lines. We assume that these lines are constrained during peak periods in a manner similar to Borenstein, Bushnell, and Stoft (2000). We find that government intervention has significant potential for adverse effects on grid resource adequacy and reliability. In our analysis, subsidized investment in baseload capacity is never optimal. Government provision of base capacity displaces competitive capacity in the short run and likely discourages the provision of peak capacity. In the long run, the threat of intervention imposes costs on suppliers in the form of an expected regulatory taking. As a result, resource adequacy decreases in both markets. If governments respond to this state of affairs by subsidizing further supply additions, expectations of intervention are reinforced and competitive capacity supply further diminishes. MOPR attempts to mitigate this vicious cycle by screening out non-economic capacity bids. To the extentMOPR succeeds in this goal and market participants view it as a credible policy, subsidized capacity additions do not perturb the efficiency of market outcomes as long as any charges to consumers to support the subsidy are lump sum in nature. In this case, subsidized resources simply succeed in capturing rents from taxpayers.

Pasteurella haemolytica is the leading cause of economic loss to the beef cattle industry in the United States and an important etiologic agent worldwide. Study of P. haemolytica is hindered by researchers' inability to genetically manipulate the organism. A new restriction endonuclease, PhaI, an isoschizomer of SfaNI (R. J. Roberts, Methods Enzymol. 65:19-36, 1980), was isolated from P. haemolytica serotype 1, strain NADC-D60, obtained from pneumonic bovine lung. PhaI recognizes the 5-base nonpalindromic sequences 5'-GCATC-3' and 5'-GATGC-3'. Cleavage occurs 5 bases 3' from the former recognition site and 9 bases 5' from the latter recognition site. A gene encoding a methyltransferase which protects against PhaI cleavage was cloned from P. haemolytica NADC-D60 into Escherichia coli. Whereas unmethylated plasmid DNA containing a P. haemolytica origin of replication was unable to transform P. haemolytica when introduced by electroporation, the same plasmid DNA obtained from E. coli which contained a cloned PhaI methyltransferase gene could do so. The data indicate that PhaI is an effective barrier to the introduction and establishment of exogenous DNA in P. haemolytica.

The aroA gene of Pasteurella haemolytica serotype A1 was cloned by complementation of the aroA mutation in Escherichia coli K-12 strain AB2829. The nucleotide sequence of a 2.2-kb fragment encoding aroA predicted an open reading frame product 434 amino acids long that shows homology to other bacterial AroA proteins. Several strategies to inactivate aroA were unsuccessful. Gene replacement was finally achieved by constructing a replacement plasmid with aroA inactivated by insertion of a P. haemolytica ampicillin resistance fragment into a unique NdeI site in aroA. A hybrid plasmid was constructed by joining the aroA replacement plasmid with a 4.2-kb P. haemolytica plasmid which encodes streptomycin resistance. Following PhaI methylation, the replacement plasmid was introduced by electroporation into P. haemolytica NADC-D60, a plasmidless strain of serotype 1A. Allelic exchange between the replacement plasmid and the chromosome of P. haemolytica gave rise to an ampicillin-resistant mutant which grew on chemically defined P. haemolytica medium supplemented with aromatic amino acids but failed to grow on the same medium lacking tryptophan. Southern blot analysis confirmed that aroA of the mutant was inactivated and that the mutant was without a plasmid.

Unpassivated AlGaN/GaN high-electron-mobility transistors show significant gate lag effects due to the presence of surface states in the region between the gate and drain contact. Low-temperature (100 °C) layers of MgO or Sc2O3 deposited by plasma-assisted molecular-beam epitaxy are shown to effectively mitigate the collapse in drain current through passivation of the surface traps. These dielectrics may have advantages over the more conventional SiNX passivation in terms of long-term device stability.

The goal of the Heavy Ion Fusion (HIF) Program is to apply high-current accelerator technology to IFE power production. Ion beams of mass {approx}100 amu and kinetic energy {>=} 1 GeV provide efficient energy coupling into matter, and HIF enjoys RD see 'Heavy Ion Accelerator Drivers.'; (2) the targets, which span a continuum from full direct to full indirect drive (and perhaps fast ignition), and have metal exteriors that enable injection at {approx}10 Hz; see 'IFE Target Designs'; (3) the near-classical ion energy deposition in the targets; see 'Beam-Plasma Interactions'; (4) the magnetic final lens, robust against damage; see 'Final Optics-Heavy Ion Beams'; and (5) the fusion chamber, which may use neutronically-thick liquids; see 'Liquid-Wall Chambers.' Most studies of HIF power plants have assumed indirect drive and thick liquid wall protection, but other options are possible.

We present the design, fabrication, and characterization of a pixelated, hyperspectral arrayed component for Focal Plane Array (FPA) integration in the Long-Wave IR. This device contains tens of pixels within a single super-pixel which is tiled across the extent of the FPA. Each spectral pixel maps to a single FPA pixel with a spectral FWHM of 200nm. With this arrayed approach, remote sensing data may be accumulated with a non-scanning, "snapshot" imaging system. This technology is flexible with respect to individual pixel center wavelength and to pixel position within the array. Moreover, the entire pixel area has a single wavelength response, not the integrated linear response of a graded cavity thickness design. These requirements bar tilted, linear array technologies where the cavity length monotonically increases across the device.

In this work, we describe the most recent progress towards the device modeling, fabrication, testing and system integration of active resonant subwavelength grating (RSG) devices. Passive RSG devices have been a subject of interest in subwavelength-structured surfaces (SWS) in recent years due to their narrow spectral response and high quality filtering performance. Modulating the bias voltage of interdigitated metal electrodes over an electrooptic thin film material enables the RSG components to act as actively tunable high-speed optical filters. The filter characteristics of the device can be engineered using the geometry of the device grating and underlying materials. Using electron beam lithography and specialized etch techniques, we have fabricated interdigitated metal electrodes on an insulating layer and BaTiO3 thin film on sapphire substrate. With bias voltages of up to 100V, spectral red shifts of several nanometers are measured, as well as significant changes in the reflected and transmitted signal intensities around the 1.55um wavelength. Due to their small size and lack of moving parts, these devices are attractive for high speed spectral sensing applications. We will discuss the most recent device testing results as well as comment on the system integration aspects of this project.

We have successfully demonstrated an integrated optical system for collecting the fluorescence from a trapped ion. The system, consisting of an array of transmissive, dielectric micro-optics and an optical fiber array, has been intimately incorporated into the ion-trapping chip without negatively impacting trapping performance. Epoxies, vacuum feedthrough, and optical component materials were carefully chosen so that they did not degrade the vacuum environment, and we have demonstrated light detection as well as ion trapping and shuttling behavior comparable to trapping chips without integrated optics, with no modification to the control voltages of the trapping chip., Comment: 14 pages, 12 figures

In this paper, we describe progress towards a multi-color spectrometer and radiometer based upon an active resonant subwavelength grating (RSG). This active RSG component acts as a tunable high-speed optical filter that allows device miniaturization and ruggedization not realizable using current sensors with conventional bulk optics. Furthermore, the geometrical characteristics of the device allow for inherently high speed operation. Because of the small critical dimensions of the RSG devices, the fabrication of these sensors can prove challenging. However, we utilize the state-ofthe-art capabilities at Sandia National Laboratories to realize these subwavelength grating devices. This work also leverages previous work on passive RSG devices with greater than 98% efficiency and ~1nm FWHM. Rigorous coupled wave analysis has been utilized to design RSG devices with PLZT, PMN-PT and BaTiO3 electrooptic thin films on sapphire substrates. The simulated interdigitated electrode configuration achieves field strengths around 3×10 7 V/m. This translates to an increase in the refractive index of 0.05 with a 40V bias potential resulting in a 90% contrast of the modulated optical signal. We have fabricated several active RSG devices on selected electro-optic materials and we discuss the latest experimental results on these devices with variable electrostatic bias and a tunable wavelength source around 1.5µm. Finally, we present the proposed data acquisition hardware and system integration plans.

We design and fabricate guided-mode resonant subwavelength gratings using an active layer of barium titanate. Loss mechanisms in the metal and in the guiding layer are investigated. Modeling and experimental results are shown.

In situ gravimetric measurements and microscopic examinations were used to determine the mechanisms of oxygen removal from synthetic ilmenite disks between 823 and 1353 K. Under a hydrogen atmosphere, iron was observed to form a layer of low porosity on the surface of samples early in the reduction. This created diffusion limitations for hydrogen to the reaction front and for the escape of water vapor. A shrinking core reduction model, modified to include the growth of this iron film, was capable of predicting the conversion-time relationships of ilmenite samples. An activation energy of 43.2 ± 2.6 kcal/gmole was determined to be representative of reaction control over the temperature range 823–1023 K.

We will discuss a passive thermal emission management surface that can manipulate the direction and wavelength bands of emission. We are designing and fabricating diffractive optics in materials that support surface-polariton plasmons. We use a grating in this material to couple the thermally-generated plasmons to photons. Grating parameters, such as grating depth and duty cycle, are varied to optimize the plasmon/photon coupling efficiency. The grating configuration ensures a phased, radiative response if the plasmon decay length along the surface traverses many grating periods. All of these parameters, material indices and dimensions, determine the specular and angular "shape" of emission.

There is a clear difference in cook‐off vulnerability between highly‐loaded pressed compositions such as LX‐14 (pressed 95.5% HMX/4.5% binder), which yield violent responses, and cast compositions with low loadings, such as CPX 301 (85% RDX/15% HTPB), which yield relatively mild responses. These two classes of composition differ primarily in the quantity of binder, and in the manufacturing method used in production. An experimental study was conducted in an attempt to determine the filling proportion beyond which violent responses are observed. Here we describe a series of small‐scale cook‐off experiments which studied pressed compositions of 88%, 91%, 95% and 96% HMX, mixed with cured, cross‐linked HTPB. The experiments used a novel glass‐windowed test vehicle, instrumented internally with thermocouples. A trend of increasing event violence with increasing proportion of HMX was found, although in none of the experiments was mass reaction recorded. The results from these experiments are discussed.

GaN-based microwave power amplifiers have been identified as critical components in Sandia's next generation micro-Synthetic-Aperture-Radar (SAR) operating at X-band and Ku-band (10-18 GHz). To miniaturize SAR, GaN-based amplifiers are necessary to replace bulky traveling wave tubes. Specifically, for micro-SAR development, highly reliable GaN high electron mobility transistors (HEMTs), which have delivered a factor of 10 times improvement in power performance compared to GaAs, need to be developed. Despite the great promise of GaN HEMTs, problems associated with nitride materials growth currently limit gain, linearity, power-added-efficiency, reproducibility, and reliability. These material quality issues are primarily due to heteroepitaxial growth of GaN on lattice mismatched substrates. Because SiC provides the best lattice match and thermal conductivity, SiC is currently the substrate of choice for GaN-based microwave amplifiers. Obviously for GaN-based HEMTs to fully realize their tremendous promise, several challenges related to GaN heteroepitaxy on SiC must be solved. For this LDRD, we conducted a concerted effort to resolve materials issues through in-depth research on GaN/AlGaN growth on SiC. Repeatable growth processes were developed which enabled basic studies of these device layers as well as full fabrication of microwave amplifiers. Detailed studies of the GaN and AlGaN growth of SiC were conducted and techniques to measure the structural and electrical properties of the layers were developed. Problems that limit device performance were investigated, including electron traps, dislocations, the quality of semi-insulating GaN, the GaN/AlGaN interface roughness, and surface pinning of the AlGaN gate. Surface charge was reduced by developing silicon nitride passivation. Constant feedback between material properties, physical understanding, and device performance enabled rapid progress which eventually led to the successful fabrication of state of the art HEMT transistors and amplifiers.

Maternally derived allergens may be transferred to the developing infant during pregnancy and lactation. However, it is not known how manipulation of environmental allergen levels might impact on this early-life exposure.To measure dietary egg allergen (ovalbumin (OVA)) in gestation-associated environments, in relation to maternal dietary egg intake.OVA was measured by allergen-specific ELISA in maternal blood collected throughout pregnancy, infant blood at birth (umbilical cord) and in breast milk at 3 months post-partum. Samples derived from pregnant women undergoing diagnostic amniocentesis at 16-18 weeks gestation who were not subject to any dietary intervention, and from pregnant women, with personal or partner atopy, randomized to complete dietary egg exclusion or an unmodified healthy diet before 20 weeks gestation as a primary allergy prevention strategy. Maternal dietary egg intake was monitored closely throughout the study period by diary record and serial measurement of OVA-specific immunoglobulin G concentration.Circulating OVA was detected throughout pregnancy in 20% of women and correlated with both presence (P0.001) and concentration (r=0.754, P0.001) of infant OVA at birth (umbilical cord). At 3 months post-partum OVA was detected in breast milk samples of 35% women, in higher concentrations than measured in blood. Blood and breast milk OVA were not related to maternal dietary intake or atopic pre-disposition.Rigorous dietary egg exclusion does not eliminate trans-placental and breast milk egg allergen passage. This early-life exposure could modulate developing immune responses.

Background: The severity of allergic reactions to food appears to be affected by many interacting factors. It is uncertain whether challenge-based reactions reflect the severity of past reactions or can predict future risk. Objective: To explore the relationship of a subject's clinical history of past reactions to the severity of reaction elicited by a low-dose, double-blind, placebo-controlled food challenge (DBPCFC) with peanut. Method: Cross-sectional questionnaire assessment of community-based allergic reactions and low-dose DBPCFC in self-selected peanut-allergic subjects. Reaction severity was assessed using a novel scoring system, taking account of the dose of allergen ingested. Results: Forty subjects (15 males, 23 children, 23 asthmatics by history) were studied. Only the most recent community reaction predicted the severity of reaction in the DBPCFC, but even this association was weak (r=0.37, P=0.03). Peanut-specific IgE (PsIgE) and skin prick test (SPT) weal size were not associated with community score but PsIgE level correlated well with the challenge score (r=0.6, P=0.001). Asthma did not affect the eliciting dose or challenge score directly but the association of PsIgE and challenge score was stronger in those without asthma (r=0.72, P=0.001) than in those with asthma (r=0.48, P=0.02). Conclusions: The scoring system developed appears to improve the sensitivity of assessment of reactions induced by DBPCFC. This is the first prospective study showing an association between PsIgE levels and clinical reactivity in DBPCFC, an effect that is more pronounced in non-asthmatics. This finding has important implications for the clinical care of subjects with food allergy. There is a poor correlation between the severity of reported reactions in the community and the severity of reaction elicited during low-dose DBPCFC with peanut.

Examines trends in the mathematics scores of different racial-ethnic groups over time and analyzes how changes in family, school, and schooling measures help explain changes in the test score gaps. Although there were few positive changes between schools, the within-school experiences of black and Latino students changed for the better compared with white students when measured by student self-reported academic track placement.

In this paper, high temperature hydrogen gas sensors with GaN and SiC based Schottky diodes were studied using Pd and Pt as Schottky contacts. Here we investigated thermal stability of W and WSi based Schottky metals for high temperature gas sensing. Schottky characteristics were observed for Au/Ti/W/SiC up to 900/spl deg/C annealing.

Mannheimia(Pasteurella)haemolytica serotype 1 is the primary causative agent responsible for bovine pneumonic mannheimiosis, also known as shipping fever in cattle. The bacterium produces a variety of virulence factors, foremost of which is the exotoxic leukotoxin. The leukotoxin is a calcium-dependent cytolysin that is a member of the RTX (repeats in toxin) family and exhibits a narrow cell-type and species specificity and has biological effects only on ruminant leukocytes and platelets. The genetic organization of the leukotoxin is comprised of four genes: lktC , lktA , lktB and lktD . The lktA structural gene encodes the protoxin (pro-LktA) and lktC encodes a transacylase that post-translationally modifies the inactive pro-LktA to a biologically active wild-type leukotoxin (LktA). The LktA has been implicated as the key factor that contributes to the pathogenesis of lung injury associated with the disease and considerable efforts have been employed in abrogating toxin function while retaining immunogenicity, with an eye towards design of attenuated vaccines. We hypothesized that the pro-LktA retains the ability to cause biological effects on target cells as has been reported in the case of the closely related RTX toxin α-hemolysin (HlyA). We also examined the biological effects of an amino-terminal truncation mutant leukotoxin ΔLktA on target cells. Thus the objectives of our study were to investigate whether two different mutant leukotoxins, one a nonacylated pro-LktA, and the other lacking 344 amino acids at the N-terminal end of the LktA protein; ΔLktA, are capable of (i) binding to the β2-integrin leukotoxin receptor, (ii) inducing the elevation of second messenger intracellular calcium ([Ca 2+ ] i ), and (iii) inducing inflammatory gene expression, reactive oxygen metabolites (ROMs) and cytolysis in target cells. Our results demonstrate that neither acylation nor the amino terminal 344 amino acids are required for LktA binding but are essential for LktA-induced [Ca 2+ ] i elevation, generation of ROM, generation of the inflammatory cytokine IL-8 and cytolysis in target cells.

During our studies on tonsillar colonization by Pasteurella haemolytica, we consistently found Escherichia coli to be one of the most prominent and prevalent bacterial species in the tonsils of healthy cattle. Since tonsillar isolates have not been characterized, we grouped 124 isolates from 87 healthy cattle from eight sources by hemolytic zone size and by carbon source utilization and probed them for selected virulence genes. They formed 3 groups by hemolytic zone size and 18 groups (of 2 to 31 isolates) by their metabolic patterns. Most groups included isolates from more than one source. Two isolates contained the Shiga-like toxin gene, and nine others contained the F41 accessory gene.

This paper presents the design for a HACT-based tapped delay line for adaptive equalization of frequency selective multipath faded channels for a wireless terrestrial digital microwave communication system. This approach allows monolithic integration of the electronics and improvements in insertion loss and noise figure over the SAW approach currently used in this system. >

A contacted electroreflectance technique was used to characterize the electronic properties of AlGaN/GaN heterostructure field-effect transistors (HFETs). By studying variations in the electroreflectance with applied electric field, spectral features associated with the AlGaN barrier, the 2-dimensional electron gas at the interface, and bulk GaN were observed. Barrier-layer composition and electric field were determined from the AlGaN Franz-Keldysh oscillations. Comparing HFETs grown on SiC and sapphire substrates, the measured AlGaN polarization electric field (0.25±0.05 MV/cm) approached that predicted by a standard model (0.33 MV/cm) for the higher mobility HFET grown on SiC.

In this paper we report new experimental results on the detonation characteristics of nitromethane containing high volume percentages of essentially inert additives. In particular, we have studied the detonation of packed beds of small spherical glass and aluminium particles saturated with pure nitromethane. These mixes are found to have reduced detonation velocities and critical diameters compared to the liquid explosive alone. We conclude with a general discussion of the propagation mechanism in such materials.

Since InGaP/GaAs heterojunction bipolar transistors (HBTs) are utilized in a wide variety of RF and other applications, a great deal has been learned about their reliability. Nevertheless, this knowledge is limited by the fact that most reliability studies heavily emphasize the stress-related evolution of a single parameter, the DC current gain, beta. We have found that interrupted stressing experiments, with complete characterization of HBTs during the interruption, can give a more complete picture of the degradation that occurs during bias stressing of HBTs. We have previously correlated electrical signatures with degradation in step-stressing of packaged InGaP/GaAs HBTs [1]. In this work we will present some results of step-stress experiments which have been conducted at the wafer level for InGaP/GaAs HBTs. Wafer-level evaluation is advantageous due to the potential for greater automation and flexibility in the testing as well as the ability to identify problems at an earlier stage in the process. The HBTs are stressed at room temperature at a constant collector voltage. Stressing is initiated at a given base current, held for a fixed time, which is typically 10 s. The applied stress is stepped up to a higher level of base current and the process is iterated until a failure is recorded. Full DC parametric electrical characterization of the HBT gets carried out initially and after certain predefined stress steps. Although the stress is typically carried near room temperature, it is understood that the junction of the HBT is effectively self-heated and can reach extremely high temperatures. A certain set of degradation processes are responsible for stress-induced failures and these occur singly or in combinations. In addition, many HBTs within a wafer and among duplicate wafers have not only a number of common failure modes, but a tendency towards a consistently realized destructive power limit. The consistency of these results and the utility of electrical signature analysis lead us to conclude that wafer-level step-stressing is an excellent tool for quickly monitoring the HBT quality. We have also found many commonalities in the wafer-level and package level results for the ceramic packages used in a previous study [1]. The degradation of HBTs by these stressing methods leads eventually to a large drop in current gain. Thus, the interrupted step stressing method arrives at the same end state as continuous, single-parameter monitoring, but with much more clarity about the degradation processes that occur on the way to the end state. The interrupted step-stress process in combination with electrical signature analysis is very likely to find the weak link in an HBT process. We will discuss the utility of the technique in terms of the opportunities to ruggedize the process. It is also possible that the identified weak link is fundamental to the technology or inconsequential in terms of meeting reliability requirements. In that case, wafer-level step-stressing is still an excellent tool for early identification of quality issues that may affect reliability through monitoring the consistency (or lack thereof) in degradation observed across different wafers over different periods of time. A.G. Baca, A.J. Scruggs, A. Gorenz, T.R. Fortune, J.F. Klem, R.D. Briggs, J.B. Clevenger, G.A. Patrizi, and C.T. Sullivan, “A Survey of Electrical Signatures Characteristic of Step-Stressed InGaP/GaAs HBTS,” ECS Transactions vol. 50 (6), pp. 273-282 (2012). Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

Great strides have been made in the development of ultraviolet LED materials and devices. Power levels in the near UV (below 390 nm) have been improved from the 10 W to the 1 mW level through improvements in the growth and design of AlInGaN alloys. High frequency AlGaN/GaN HEMTs have been developed with ft of 65 GHz and fmax of 85 GHz, all while attaining breakdown voltage greater than 100 V. A new breakthrough in the lateral overgrowth of GaN materials promises to further improve these devices.

The great scallop is a highly valued marine species. It makes its home on rocky seabeds around the British Isles and has been heavily exploited. Fears that natural stocks are showing signs of over fishing are being remedied by strict enforcement of fisheries legislation and by the development of stock enhancement practices.

Massively parallel optical interconnects are appropriate to ease the data bandwidth bottleneck that will occur in future computing applications. Vertical cavity surface emitting lasers (VCSELs) are promising sources for emerging 2D optical systems such as free space and guided wave optical interconnects. We discuss the development of high performance VCSEL arrays, including individually addressable and matrix addressable arrays. We also show the characteristics of GaAs microelectronic driver and photoreceiver chips that have been designed to interface with Si-based CMOS circuitry. Finally, the potential of these source and receiver modules for use in free space or guided wave parallel channel optical interconnect architectures will be described.

Vertical cavity surface emitting lasers (VCSELs) which operate in multiple transverse optical modes have been rapidly adopted into present data communication applications which rely on multi-mode optical fiber. However, operation only in the fundamental mode is required for free space interconnects and numerous other emerging VCSEL applications. Two device design strategies for obtaining single mode lasing in VCSELs based on mode selective loss or mode selective gain are reviewed and compared. Mode discrimination is attained with the use of a thick tapered oxide aperture positioned at a longitudinal field null. Mode selective gain is achieved by defining a gain aperture within the VCSEL active region to preferentially support the fundamental mode. VCSELs which exhibit greater than 3 mW of single mode output power at 850 nm with mode suppression ratio greater than 30 dB are reported.

Ultra high-speed digital photography has been used to record the onset and build-up of reaction in nitromethane charges that have been impacted by steel fragments. The nitromethane charges were housed in PMMA cylinders and back-lit using conventional flash bulbs. Flat plates of aluminum were glued to one end of the cylinder and PMMA plates to the other. The completed charge was positioned to allow normal impact of the projectiles through the aluminum barrier plate. The events were filmed using an Imacon 468, ultra high-speed digital image system, capable of framing at up to 100 million pictures per second. Using this system it was possible to record detailed photographic information concerning the onset and growth of reaction due to shock initiation of the nitromethane charges. The results obtained to date are consistent with the established concepts for initiation of homogeneous and heterogeneous materials.

Mobility problems experienced by elderly people with a dementia are associated with falls, fractures and admission to long-term care. A hospital respite care admission is therefore often seen as an opportunity to provide physiotherapy treatment.To find whether elderly people with a dementia and a mobility problem show a greater improvement in mobility skills if given physiotherapy treatment than if given non-physical activities intervention during a hospital respite admission.A controlled randomized multicentre trial with independent blinded assessment. The Southampton Mobility Assessment (mobility score) and Two Minute Walking Test (distance walked) were undertaken at the beginning and end of the study admission and beginning of the next respite admission. Following the first assessment, participants were randomized to either physiotherapy or activities.Eighty-one participants, from 12 clinical centres, with a mean age of 81.9 years and CAPE I/O score of 2. During the study admission there was a non-significant trend for a lower reduction in mobility score of the physiotherapy group (Mann-Whitney; p = 0.614) and a non-significant trend for greater decrease in distance walked in the activities group (t-test; p = 0.325).The results of this trial do not support the positive changes demonstrated elsewhere. However, changes in respite care during the early stages of this trial may have produced differences between the sample for this trial and that for the pilot study. This trial was therefore underpowered.This trial suggests that future research needs to change the focus from clinical settings to presentations.

Optocouplers are used for a variety of applications aboard spacecraft including electrical isolation, switching and power transfer. Commercially available light emitting diode (LED)-based optocouplers have experienced severe degradation of light output due to extensive displacement damage occurring in the semiconductor lattice caused by energetic proton bombardment. A new optocoupler has been designed and fabricated which utilizes vertical cavity surface emitting laser (VCSEL) and resonant cavity photodetector (RCPD) technologies for the optocoupler emitter and detector, respectively. Linear arrays of selectively oxidized GaAs/AlGaAs VCSELS and RCPDS, each designed to operate at a wavelength of 850nm, were fabricated using an airbridge contacting scheme. The airbridged contacts were designed to improve packaging yields and device reliability by eliminating the use of a polyimide planarizing layer which provided poor adhesion to the bond pad metallization. Details of the airbridged optocoupler fabrication process are reported. Discrete VCSEL and RCPD devices were characterized at temperatures between {minus}100 to 100 C. Devices were packaged in a face-to-face configuration to form a single channel optocoupler and its performance was evaluated under conditions of high-energy proton bombardment.

To evaluate the effects of loteprednol etabonate (LE) 0.2% in reducing the signs and symptoms of seasonal allergic conjunctivitis.Randomized, double-masked, placebo-controlled, parallel group multicenter study of 6 weeks duration.A total of 135 patients with signs and symptoms of seasonal allergic conjunctivitis participated.All patients received either LE 0.2% or placebo (vehicle) four times a day in both eyes for 42 days.Bulbar conjunctival injection (primary sign) and itching (primary symptom) over the first 2 weeks of treatment was measured.A reduction in severity was seen in both LE and placebo groups for bulbar conjunctival injection (1.5 vs. 1.0 units on a 0-3 scale) and itching (3.4 vs. 3.0 units on a 0-4 scale) over the first 2 weeks. The treatment effect by these measures was -0.5 and -0.4 units in favor of LE (Por = 0.008). Resolution (i.e., the proportion of patients with signs or symptoms no longer present) at day 14 strongly favored LE-treated patients (36% and 15%; 58% and 38%, for injection and itching, respectively). Both treatments were well tolerated. One patient in each treatment group (1 of 67 and 1 of 68, respectively) had an elevation of intraocular pressure of 10 mmHg or greater during the 6 weeks of treatment.Loteprednol etabonate 0.2% was more effective than placebo in the treatment of seasonal allergic conjunctivitis. Loteprednol etabonate 0.2% had a safety profile comparable to placebo.

To determine the prevalence of antibody to bovine adenovirus (BAdV) serotypes 1-8 and 10 in calves at a farm and after 5 weeks in a feedyard.2- to 5-month-old calves of mixed English breeding (n = 100) from 4 farms.Serum BAdV antibody was measured by use of a microtitration test.Serum antibodies were found to the 9 BAdV serotypes studied. Seroconversion to each virus had occurred in some calves by the time the second serum sample had been obtained, indicating that the BAdV were present and inducing active infection in these calves.Antibody to BAdV serotypes 1-8 and 10 are present in cattle populations of the United States, indicating existence of these serotypes, although only BAdV serotypes 1-4, 7, and 10 have been isolated.

The human myeloid nuclear differentiation antigen, MNDA, is expressed only in myelomonocytic and a subset of B lymphoid hematopoietic cells. MNDA is uniformly distributed throughout the interphase cell nucleus and associates with chromatin, but does not bind specific DNA sequences. We recently demonstrated that MNDA binds nucleolin and nucleophosmin/NPM/B23 and both of these nuclear proteins bind the ubiquitous zinc finger transcription factor YY1. Investigations of the possible effect of MNDA on the interaction between YY1 and NPM, showed that MNDA bound YY1 directly under both in vitro and in vivo conditions. The MNDA-YY1 interaction enhanced the affinity of YY1 for its target DNA and decreased its rate of dissociation. The N-terminal half (200 amino acids) of MNDA was sufficient for maximum enhancement of YY1 DNA binding and a portion of this sequence was responsible for binding YY1. MNDA participated in a ternary complex with YY1 and the YY1 target DNA element. The results show that MNDA affects the ability of YY1 to bind its target DNA sequnce and that MNDA participates in a ternary complex possibly acting as a cofactor to impart lineage specific features to YY1 function.

To determine the rate and mode of infectious spread of Pasteurella haemolytica among calves maintained under typical conditions during collection, transport, and the first month of feeding.101 two- to five-month-old Angus-crossbred calves.Samples obtained from cattle prior to and after they were transported to a feedlot were used for isolation and characterization of P haemolytica. Samples were also obtained from additional calves, some of which were sick, and these calves were then commingled with the transported calves for 3 days. A strain of P haemolytica that contains a rare deletion of the 4.2-kilobase streptomycin- and sulfonamide-resistance plasmid was inoculated into both palatine tonsils of 12 calves. Nasal secretions were aspirated from the ventral nasal meatus. Tonsillar wash specimens were procured. Pasteurella haemolytica organisms were quantitatively cultured and identified on the basis of colony morphology and response to specific antisera. Plasmids were isolated by an alkaline lysis procedure and identified by agarose gel electrophoresis.A single plasmid profile was observed from P haemolytica isolated from samples obtained prior to shipment. Commingled calves were shedding P haemolytica containing each known plasmid profile. After shipment, samples contained P haemolytica isolates with each known plasmid profile. The plasmid profile of the unique P haemolytica isolate was recovered from all 12 inoculated calves and 10 other calves. Some calves simultaneously shed P haemolytica isolates with differing plasmid profiles.Pasteurella haemolytica serotype 1 was horizontally transmitted among calves within days of commingling, which continued after calves were transported to a feedlot.

To develop a unique strain of Pasteurella haemolytica, selectable from nasopharyngeal respiratory tract secretions, that retains the ability to efficiently colonize the respiratory tract of calves.26 calves that each weighed approximately 200 kg.Rifampicin-resistant mutants of P haemolytica were developed and tested for in vitro growth rate and leukotoxin production. After instillation into the tonsils of calves, an isolate that was efficient at colonizing was selected and transformed, using electroporation, with a 4.2-kilobase (kb) plasmid encoding for streptomycin resistance. This isolate was instilled into the tonsils of 4 of 14 commingled calves to examine transmission of organisms. Nasal secretion and tonsil wash specimens were collected, cultured, and examined for P haemolytica. Serum antibody concentration was measured by means of indirect hemagglutination.Selected P haemolytica organisms colonized the tonsils and nasal passages for more than 2 weeks. Exposed calves and contact calves shed the organism, which was recovered from specimens of nasal secretions and tonsil washes. The 4.2-kb plasmid was lost during in vivo colonization.The selected rifampicin-resistant P haemolytica organism colonized tonsils and nasal passages in a manner similar to the wild-type organisms. Selective media suppressed other bacterial flora to the extent that a single colony-forming unit was detectable from 200 microl of specimen, a 100-fold improvement in detection sensitivity. The selectable strain spread rapidly among commingled calves. A 4.2-kb plasmid marker was unstable when P haemolytica replicated in vivo.

The myeloid cell nuclear differentiation antigen (MNDA) is a nuclear protein expressed specifically in developing cells of the human myelomonocytic lineage, including the end-stage monocytes/macrophages and granulocytes. Nuclear localization, lineage- and stage-specific expression, association with chromatin, and regulation by interferon alpha indicate that this protein is involved in regulating gene expression uniquely associated with the differentiation process and/or function of the monocyte/macrophage. MNDA does not bind specific DNA sequences, but rather a set of nuclear proteins that includes nucleolin (C23). Both in vitro binding assays and co-immunoprecipitation were used to demonstrate that MNDA also binds protein B23 (nucleophosmin/NPM). Three reciprocal chromosome translocations found in certain cases of leukemia/lymphoma involve fusions with the NPM/B23 gene, t(5;17) NPM-RARalpha, t(2;5) NPM-ALK, and the t(3;5) NPM-MLF1. In the current study, MNDA was not able to bind the NPM-ALK chimera originating from the t(2;5) and containing residues 1-117 of NPM. However, MNDA did bind the NPM-MLF1 product of the t(3;5) that contains the N-terminal 175 residues of NPM. The additional 58 amino acids (amino acids 117-175) of the NPM sequence that are contained in the product of the NPM-MLF1 fusion gene relative to the product of the NPM-ALK fusion appear responsible for MNDA binding. This additional NPM sequence contains a nuclear localization signal and clusters of acidic residues believed to bind nuclear localization signals of other proteins. Whereas NPM and nucleolin are primarily localized within the nucleolus, MNDA is distributed throughout the nucleus including the nucleolus, suggesting that additional interactions define overall MNDA localization.