Material growth and characterization for solid state devices

Manganese was used as the dopant for p-type InGaAs layers grown on semi-insulating (Fe-doped) and n-type (Sn-doped) InP substrates. Optical, electrical (Hall) and SIMS measurements were used to characterize the layers. Mn-diffusion into the substrate (during the growth of In GaAs) was observed only when Fe-doped substrates were used. Quaternary layers of two compositions corresponding to wavelengths (energy gaps) of approximated 1.52 micrometers were successfully grown at a constant temperature of 640 C and InP was grown in the temperature range of 640 C to 655 C. A study of the effect of pulses on the growth velocity of InP indicated no significant change as long as the average applied current was kept constant. A system for depositing films of Al2O3 by the pyrolysis of aluminum isopropoxide was designed and built. Deposited layers on Si were characterized with an ellipsometer and exhibited indices of refraction between 1.582 and 1.622 for films on the order of 3000 A thick. Undoped and p-type (Mn-doped) InGaAs epitaxial layers were also grown on Fe-doped InP substrates through windows in sputtered SiO2 (3200 A thick) layers

Material growth and characterization directed toward improving III-V heterojunction solar cells

In addition to the existing materials growth laboratory, the photolithographic facility and the device testing facility were completed. The majority of equipment for data acquisition, solar cell testing, materials growth and device characterization were received and are being put into operation. In the research part of the program, GaAs and GaA1As layers were grown reproducibly on GaAs substrates. These grown layers were characterized as to surface morphology, thickness and thickness uniformity. The liquid phase epitaxial growth process was used to fabricate p-n junctions in Ga(1-x)A1(x)As. Sequential deposition of two alloy layers was accomplished and detailed analysis of the effect of substrate quality and dopant on the GaA1As layer quality is presented. Finally, solar cell structures were formed by growing a thin p-GaA1As layer upon an epitaxial n-GaA1As layer. The energy gap corresponding to the long wavelength cutoff of the spectral response characteristic was 1.51-1.63 eV. Theoretical calculations of the spectral response were matched to the measured response

A Bovine Monstra Duplica

Double monsters are pathological deviants from identical twins, in that the embryos are joined in some manner. The embryos may be symmetrically united and developed, or one of the individuals may he arrested in its development. In describing the morphological relationships of the calf of this study, the right and left sides will refer to the animal\u27s right and left respectively. From a superficial examination of this specimen it appears to be a single-bodied calf with two heads, an extra leg with two hooves protruding from the hack a short distance caudal to the vertex of the two heads, and two tails. These facts indicate that there are two animals in this union, hut this indication is not carried out on the ventral surface as there are only four teats and one opening for the umbilical vessels to enter the body

Observed limiting cases of horizontal field coherence and array performance in a time-varying internal wavefield

Author Posting. © Acoustical Society of America, 2008. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 124 (2008): EL97-EL103, doi:10.1121/1.2947630.Using a moored source and horizontal/vertical line array combination, horizontal coherence properties of high signal to noise ratio (>=20 dB) 100–1600 Hz signals have been measured. Internal waves in the area of the measurement created moving episodic sound-speed anomaly structures, influencing coherence length. Measured horizontal coherence scales for 100 Hz ranged from 5 to 20 acoustic wavelengths, and were inversely related to the sound-speed anomaly strength. Horizontal field properties were compared with fields computed using modal decompositions of the vertical signals. The comparison allows azimuthal field coherence properties to be studied apart from normal-mode interference effects.This work was funded by grants to Boston University and the Woods Hole Oceanographic Institution from the Ocean Acoustics Program at the U.S. Office of Naval Research, including an ONR Postdoctoral Fellowship award to the first author

In situ hybridisation and S1 mapping show that the presence of infiltrating plasma cells is associated with poor prognosis in breast cancer.

In order to identify potential markers of prognosis in breast cancer, representative cDNA libraries were constructed using RNA isolated from primary breast tumour tissue associated with good and poor prognosis. Cross-screening of these libraries repeatedly identified cloned mRNA species associated with the immune system, in particular B-cells, in libraries derived from tumours of poor prognosis. We have used one of these a kappa IV light chain cDNA probe, in two complementary studies to investigate the relationship between immunoglobin gene expression and prognosis. The results obtained using a combination of S1 mapping, RNA blotting and in situ hybridisation demonstrate that the presence of plasma cells, as defined by infiltrating cells which express high levels of immunoglobulin kappa-chain mRNA, is associated with a poor prognosis

Characterization of Drawn and Undrawn Poly-L-Lactide Films by Differential Scanning Calorimetry

Poly-L-lactic acid (PLLA) is an optically active, biocompatible and biodegradable polymer that has been widely investigated as an artificial cell scaffold material. In its most crystalline form, PLLA is highly anisotropic and is one of the most piezoelectric polymers known. Conversely, amorphous PLLA exhibits little, if any, piezoelectric behavior. Compression molded PLLA films can be endowed with varying amounts of crystalline character and piezoelectricity by uniaxially stretching the polymer in a hot air bath. Understanding the precise crystalline architecture of PLLA that results from tensile drawing is important for constructing cell scaffolds that have highly tailored biodegradation and cell guiding properties. In our work here, we investigate the changes in the thermal properties of PLLA at draw ratios between 1.0 and 5.5 using differential scanning calorimetry (DSC). The crystallinity of the compression molded undrawn starting material is characterized using X-ray diffraction. Our DSC results show an increase in percent crystallinity with increasing draw up to a draw ratio of 4.0. At greater draw ratios, there is a decrease in the crystalline character exhibited by PLLA

Cyprus' image—a sun and sea destination—as a detrimental factor to seasonal fluctuations. Exploration into motivational factors for holidaying in Cyprus

Cyprus is established as a summer destination. To aid the destination in developing its winter season as well, this research uses a qualitative inductive approach to explore the tourists’ current image of the island and their motivations of visiting it. The research indicates that the current image, which essentially portrays Cyprus as a sun-and-sea destination is thought to dissuade tourists from perceiving the island as a year-round destination. Nonetheless, increasing the pull factors of the destination through the development of unique special interest products can help in extending the tourism season as well as broaden its narrow image

In Vitro Recombination Catalyzed by Bacterial Class 1 Integron Integrase IntI1 Involves Cooperative Binding and Specific Oligomeric Intermediates

Gene transfer via bacterial integrons is a major pathway for facilitating the spread of antibiotic resistance genes across bacteria. Recently the mechanism underlying the recombination catalyzed by class 1 integron recombinase (IntI1) between attC and attI1 was highlighted demonstrating the involvement of a single-stranded intermediary on the attC site. However, the process allowing the generation of this single-stranded substrate has not been determined, nor have the active IntI1•DNA complexes been identified. Using the in vitro strand transfer assay and a crosslink strategy we previously described we demonstrated that the single-stranded attC sequences could be generated in the absence of other bacterial proteins in addition to IntI. This suggests a possible role for this protein in stabilizing and/or generating this structure. The mechanism of folding of the active IntI•DNA complexes was further analyzed and we show here that it involves a cooperative binding of the protein to each recombination site and the emergence of different oligomeric species specific for each DNA substrate. These findings provide further insight into the recombination reaction catalyzed by IntI1

Determinants of voluntary audit and voluntary full accounts in micro- and non-micro small companies in the UK

This is an Author's Accepted Manuscript of an article published in Accounting and Business Research, 42(4), 441 - 468, 2012, copyright Taylor & Francis, available online at: http://www.tandfonline.com/10.1080/00014788.2012.667969.This study investigates the link between the auditing and filing choices made by a sample of 592 small private companies, which includes 419 micro-companies. It examines decisions made in connection with the 2006 accounts following UK's adoption of the maximum EU size thresholds in 2004, and the impact of the proposed Directive on the annual accounts of micro-companies. The research extends the model of cost, management and agency factors associated with voluntary audit, and develops a complementary model for voluntary full accounts. The results show the benefits of placing full audited accounts on public record that outweigh the costs for a significant proportion of companies. In non-micro small companies, voluntary audit is determined by cost and agency factors, whereas in micro-companies it is driven by cost, management and agency factors. In both groups, the predictors of voluntary full accounts include management and agency factors, and choosing voluntary audit is one of the key factors. The study provides models that can be tested in other jurisdictions to provide evidence of the needs of micro-companies, and the discussion of the methodological challenges for small company researchers in the UK makes further contribution to the literature