Modeling of the Saturation Characteristics of High Voltage Transistors

The conventional Ebers-Moll model does not provide an accurate representation of the saturation region characteristics for transistors with a high resistivity collector region. Accurate one-dimensional calculations of device characteristics indicate that the size of the effective collector resistance is modulated at high currents by the extension of the neutral base into the collector region. Based on this analysis, a non-linear collector resistance is added to the Ebers-Moll equivalent circuit model to provide a more accurate representation of the characteristics in the saturation region.     

Improving the Professional Engineering Licensure Process for Construction Engineers

Professional engineering licensure is important in the career development of engineers who undertake work critical to protecting public health, safety, and welfare. The knowledge and experience of construction engineers has not previously been well represented in professional engineering licensure evaluation. The ASCE-CI Construction Engineering Education Committee identified recognition of construction engineering in the professional engineering licensure process as one of its missions when it was organized in 1995. With the support of the states and the receptiveness of the National Council of Examiners for Engineering and Surveying (NCEES), improvements were gradually achieved in recognition of construction engineering experience by changes in NCEES Model Rules. In 2003, the NCEES Board decided to evaluate modification of the Civil Engineering PE exam to include a Construction Engineering module. The evaluation included a Professional Activities and Knowledge Study (PAKS) of the skills appropriate for construction engineers. Following approval of the NCEES Board in 2005, exam development has been underway with implementation planned for April 2008. An additional benefit of the PAKS is the improved understanding of knowledge needed by construction engineers in completing their work activities. These results should be valuable to construction engineering education and industry in identifying critical subject matter for inclusion in courses, curriculums, and continuing education.     

Characterisation of Phenolic Compounds in Oils Produced from Frosted Olives

Frost is one of the most important weather related hazards for the Australian olive industry and it has caused significant economic losses during the last decade. Its impact on oil quality was significant in 2006 with more than 20% of Australian oil of that year being affected to some degree. Early frosts will normally affect the fruit leading to significant changes in the chemical and organoleptic characteristics of the oils. The aim of this work was to study the effect of freeze damage on the phenolic composition and quality parameters of oils from three different varieties: Frantoio, Barnea and Picual. Quality chemical parameters showed significant differences in oils produced from fruit that was frozen for 2 and 4 weeks. Those chemical parameters were not significantly different in the oil produced from fruit immediately after being frosted. Nonetheless, the sensorial profile and the polyphenols showed significant changes even with oils produced within a short time after the freezing event. Those changes became more evident with the oils produced at increasing time from the moment of fruit freezing.     

Cryptanalysis: a survey of recent results

Cryptosystems are tested by subjecting them to cryptanalytic attacks by experts. Most of the cryptosystems that have been publicly proposed in the last decade have been broken. Some of the attacks that have been used are outlined, and some of the basic tools available to the cryptanalyst are explained. Attacks on the knapsack cryptosystems, congruential generators, and a variety of two key secrecy and signature schemes are discussed. There is also a brief discussion of the status of the security of cryptosystems for which there is no known feasible attack, such as the RSA, discrete exponentiation, and DES cryptosystems     

Effects of the synthetic anti-oxidant, probucol, on the U937 monoblastoid cell line

We examined physiological events in the hyperplastic artery, using a method based on the mechanical responsiveness and myosin light-chain phosphorylation in response to various stimulants. Six weeks after endothelial denudation by ballooning of the right carotid artery, strips of this artery with moderate intimal hyperplasia (intimal area was 30-50% of medial area in 20 of 28 rabbits) were used for experiments. Strips from the left carotid served as the normal control. When the hyperplastic artery was stimulated with 30 microM PGF2 alpha, the maximal tension (232.4 +/- 49.1 mg/mg dry wt, mean +/- SD) was significantly higher (P < 0.05) than that of the control (129.5 +/- 16.4 mg/mg). The maximal extent of myosin light-chain monophosphorylation (45.4 +/- 8.9%) and diphosphorylation (10.9 +/- 5.2%) in the hyperplastic artery was significantly higher (P < 0.05) than that in the control artery (33.0 +/- 4.8 and 4.0 +/- 4.8%, respectively). The monophosphorylation of the myosin light chain in the hyperplastic artery was sustained for up to 20 min, while that in the control artery decreased to the basal level within 20 min. Similar observations were obtained by stimulation with 60 mM K+ or 30 microM norepinephrine. Dose-response curves of the development of tension in the hyperplastic artery to various agonists (K+, PGF2 alpha, norepinephrine) shifted upward the curves for the control artery. These results suggest that qualitative changes in the characteristics of smooth muscle cells may occur in the intimal hyperplastic portion, including a hyperreactive contraction associated with enhanced and sustained phosphorylation of the myosin light chain.     

A descriptive study of the survival of Holstein-Friesian heifers through to third calving on English dairy farms

A short herd lifespan severely limits opportunities for on-farm selection of breeding cows in addition to causing financial losses on dairy farms and presenting welfare issues for individual animals. This prospective study monitored survival up to third calving and reasons for culling of a cohort of 468 Holstein-Friesian heifers on 18 dairy farms across southern England. Heifers born during 2003 and 2004 were monitored from 1 mo of age through to third calving. A longevity index was calculated as the proportion of days alive spent in milk production, a good measure of lifetime performance. On average, 11% of heifers recruited at 1 mo did not survive until first calving (0% longevity index). Of those that did calve, 19% were culled in lactation 1 (total average lifetime days in milk of 322 with a longevity index of 24%) and 24% were culled during lactation 2 (total average lifetime days in milk of 623 with a longevity index of 40%). The primary cause for culling was infertility. Only 55% of replacement heifers calved successfully for a third time, ranging from 80 to 32% across individual farms. These results show that on a selection of UK farms, a large number of heifers never become productive or are culled before they reach their full lactation potential. Increasing the productive lifetime of dairy cows would improve the efficiency of dairy production by lowering replacement costs and capturing a greater proportion of potential lactation milk yield from mature cows.     

Verb learning in Parkinson's disease.

The relative roles of grammatical processing and memory in the language comprehension difficulties of patients with Parkinson's disease (PD) were evaluated. 20 PD patients who did not have dementia were exposed to a new verb in a naturalistic setting. After 10 min, the semantic and grammatical information that they learned about the new verb was probed. Significant impairments in recalling some aspect of the new verb were seen in 55% of PD patients. Most of these patients demonstrated a language-sensitive deficit in appreciating grammatical information represented in the new verb. A small number of PD patients responded randomly to probes of all information about the new word, which suggests a memory impairment. It is concluded that difficulty in appreciating grammatical information contributes to the language impairments of PD patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evidence that the Wiskott-Aldrich syndrome protein may be involved in lymphoid cell signaling pathways

Wiskott-Aldrich syndrome is an X-linked combined immunodeficiency affecting cells of several different hemopoietic lineages. The Wiskott-Aldrich syndrome protein (WASP), which has no homology with any other known protein families, is rich in proline motifs known to contribute to Src homology 3 binding sites. However, its function has not been determined. The Tec family of cytoplasmic tyrosine kinases, which include Btk (the X-linked agammaglobulinemia gene), Itk, and Tec, is thought to be involved in lymphoid cell signaling pathways. In this work, we show binding of WASP to the Src homology 3 domains of Btk, Itk, Tec, Grb2, and phospholipase C-gamma, which suggests a function for WASP in lymphoid cell signaling.     

Perceptions of climate change impacts and self-rated health in coastal Cambodia

Climate change contributes to the global burden of diseases and premature mortality. This burden may be even more pronounced in coastal areas amongst the poor and the marginalised groups. Using a survey data-set from 1823 households in coastal communities in Cambodia, we examine how perceptions on climate change impacts influence self-rated health (SRH) when controlling for livelihoods, food security and contextual and compositional factors. The findings show that individuals who had higher factor scores on perceived socio-ecological impact of climate change were less likely to report good SRH. Likewise, those who reported barriers to protect themselves against the impacts of climate change were less likely to report good health. Surprisingly, households that reported earning more were less likely to report good health.     

Continuous production of fullerenes by pyrolysis of acetylene at a glassy carbon surface

A reactor is described for generating fullerenes from hydrocarbon gas or vapor. Distinguishing features are a thermal system in which the fullerene product is not exposed to destructive energetic photons (as in an arc) and ease of control. Acetylene was chosen as the first feedstock to reduce the hydrogen content. Argon is the carrier gas. The reactor is a radio-frequency induction heated cylinder of glassy polymeric carbon having multiple holes through which the gas mixture passes. Operation as high as 2500 K is possible, but fullerene production is seen only below 1500 K. Preliminary tests give <1% yield, but improvement is expected by manipulation of the temperature, dwell time at temperature, feedstock species and partial pressure. A hydrogen scavenger may also be useful.