Interface structure and strength of ultrasonically wedge bonded heavy aluminium wires in Si-based power modules

In this paper the microscopical structure of wedge bonded interfaces is investigated, with a focus on what effect the power in the ultrasonic bonding and the initial microscopical structure of the \(Al\) wire have on the quality of the bonding. The quality evaluation is based on mapping the microscopical restructuring of the wire grains during bonding and thereby assessing the effective bonding area. Three approaches are utilized in the interface characterization: mechanical shear test, optical microscopy combined with micro-sectioning, and scanning electron microscopy assisted by focused ion beam milling. The shear test is applied to quantify the strength of the bonded interfaces, while the other methods are used to map the grain reconstruction caused by the bonding. From the results it is possible to map a 3D image of the wire deformation, and the grain refinement region which is the dominating parameter with respect to fatigue related cracking of the interfaces. It is found that the bonding power, as well as the initial wire structure directly affects the refinement region and thereby the strength of the interface.     

Power loss in the upper cut‐out wind speed interval

Time series of mean wind speeds at several sites in Denmark have been used to estimate the power loss for wind turbines in the wind speed interval from where the operation has to stop at high winds to where a lower wind speed allows the operation to resume. For inland wind turbines the fractional loss is less than 0·25%. For offshore wind turbines it may be as high as about 1·5%. To facilitate the estimation of ‘dead zone’ power loss for offshore wind turbines, an engineering model for the sea surface state has been developed on the basis of a generalization of Charnock's roughness model and the geostrophic drag law. This model predicts the surface friction velocity and the surface roughness as functions of the geostrophic wind speed and the length of the water fetch. Copyright © 2004 John Wiley & Sons, Ltd.     

What are the sciences of relationship-centered primary care

Steroidogenic acute regulatory protein (StAR), a 30-kDa protein involved in the transport of cholesterol to inner mitochondrial membrane during stimulation of steroid hormone biosynthesis, has recently been cloned from human adrenals and MA-10 mouse Leydig tumor cells. We examined the regulation of StAR mRNA accumulation upon induction of steroidogenesis in immortalized rat granulosa cells. Granulosa cells were transfected with SV40 DNA alone (POGS5); with SV40 DNA and Ha-ras oncogene (POGRS1); with SV40 DNA, Ha-ras oncogene and LH/CG receptor (GLHR15) or with FSH receptor (GFSHR17) or with the beta 2-adrenergic receptor (G beta 2AR13) expression plasmids. Cells were cultured to confluency and then stimulated for 24 h with oFSH (4 nM), hCG (2.4 nM), isoproterenol (10 microM) or forskolin (50 microM). By quantitative RT-PCR, StAR mRNA was undetectable in non-steroidogenic cells (transfected with SV40 DNA alone, POGS5) either in the presence or in the absence of forskolin. In contrast, variable amount of the message was detected in all steroidogenic cell lines cotransfected with SV40 DNA and Ha-ras. Moreover, an increase in the StAR mRNA expression was evident in all steroidogenic cells upon stimulation with their respective agonists, concomitantly with enhanced progesterone production. The RT-PCR product was sequenced and the 379 base pairs of rat StAR were found to be 93% and 86% identical to mouse and human cDNA, respectively. The deduced 126 amino acid sequence was 95%, 88% and 88% identical to the mouse, human and bovine deduced protein sequences. We conclude that StAR message is expressed only in the steroidogenic rat granulosa cells and can be upregulated by FSH, hCG, isoproterenol and forskolin in the appropriate cell lines. In addition, we find that the rat StAR cDNA exhibit a high degree of homology with the mouse and human sequences.     

Oxidative stress: an important phenomenon with pathogenetic significance in the progression of acute pancreatitis

BACKGROUND: Reactive oxygen species and related oxidative damage have been implicated in the initiation of acute pancreatitis. Changes in these parameters during disease progression merit further investigation. AIMS: To evaluate changes and the clinical relevance of superoxide radicals, endogenous antioxidants, and lipid peroxidation during the course of acute pancreatitis. PATIENTS AND METHODS: Superoxide radicals (measured as lucigenin amplified chemiluminescence), ascorbic acid, dehydroascorbic acid, alpha tocopherol, and lipid peroxidation (measured as thiobarbiturate reactive substances) were analysed in blood samples from 56 healthy subjects, 30 patients with mild acute pancreatitis, and 23 patients with severe acute pancreatitis. The association with grades of disease severity was analysed. Measurements were repeated one and two weeks after onset of pancreatitis. RESULTS: In the blood from patients with acute pancreatitis, there were increased levels of the superoxide radical as well as lipid peroxides. There was notable depletion of ascorbic acid and an increased fraction of dehydroascorbic acid. Changes in alpha tocopherol were not great except in one case with poor prognosis. Differences between severe and mild acute pancreatitis were significant (p < 0.01). Variable but significant correlations with disease severity scores were found for most of these markers. The normalisation of these indexes postdated clinical recovery one or two weeks after onset of disease. CONCLUSIONS: Heightened oxidative stress appears early in the course of acute pancreatitis and lasts longer than the clinical manifestations. The dependence of disease severity on the imbalance between oxidants and natural defences suggests that oxidative stress may have a pivotal role in the progression of pancreatitis and may provide a target for treatment.     

A comparison of the investment in hospital-based obstetrical ultrasound in Wales and Washington state

The purpose of this study was to examine differences in the way Britain and the United States invest in and deploy a new medical technology. We used structured interviews to obtain information on the technical sophistication and approximate replacement value of all hospital-based obstetrical ultrasound machines in every maternity hospital in Washington state and Wales. The supply of hospital-based ultrasound machines--approximately two machines per 1,000 births--was similar in both countries. Wales had fewer advanced ultrasound machines than Washington state, and they were based exclusively in high-volume district general hospitals; there were no obstetric ultrasound machines in the private sector. In Washington state, the majority of advanced machines were in small and medium-sized hospitals, and many private offices had ultrasound machines. The approximate replacement value of hospital-based machines was three times as high per birth in Washington state as in Wales. In the case of obstetrical ultrasound, centralization of facilities, a relatively small private sector, and global budgeting lead to lower expenditures per patient within the National Health Service without compromising access to care.     

Molecular genetics of familial hypercholesterolemia in Israel

Recreational SCUBA diving exposes individuals to environmental stresses not often encountered in other types of activity. These stresses include increased ambient pressure, raised partial pressure of O(2), increased resistance to movement, added weight and drag of diving equipment, cold stress, and a higher breathing resistance. One means to understand how such stresses affect a diver is to employ the stress-strain-adaptive response model. Physiologic adaptations, like an increase in VO(2) in response to cold stress, will minimize the strain placed on thermal balance. Nonphysiologic adaptive responses include those behavioral and equipment interventions that isolate the diver from a particular stress. Self-contained underwater breathing apparatus (SCUBA) isolates the diver from the inability to extract O(2) from the water; dive garments minimize the stress of cold water immersion. This review will focus on cardiorespiratory and thermal responses to SCUBA diving, using the stress-strain-adaptive response model to illustrate the interaction between diver and environment. Some responses like hyperventilation, cardiac arrhythmias, or cold injury due to vasoconstriction are not considered adaptive but are realistic possibilities in diving environments.     

Experimental telemedicine in orthopaedics

An accurate technique that simplifies measurements of two- and three-dimensional specimens is presented. Photomicrographs of a microruler and of the specimens of a research project were made at the same magnification. A ruler with the exact dimensions of the photographic prints of the microruler was generated through computer graphics and printed as a transparency. After verification, the ruler was used to measure specimens directly on the photomicrographs.     

Interaction of 4-(n-dimethylaminostyryl)-1-methylpyridinium-n-toluolsulfonate with liposomes: analysis of fluorescence spectra

A previous magnetic resonance imaging study from our laboratory reported significant temporal lobe volume deficits in cortical gray matter, white matter, and anterior hippocampus in chronic alcoholic men relative to controls. In the present study, we reexamined these data and asked whether withdrawal seizure history was predictive of either the hippocampal or the extrahippocampal volume deficits. A review of the medical charts indicated that 11 alcoholics had experienced one or more alcohol-related seizures and 35 were seizure-free; no patient had a seizure disorder unrelated to alcohol. The two alcoholic groups did not differ significantly in age, education, alcohol consumption variables, premorbid intelligence, Memory Quotient, Trail Making, or detection of hidden figures. Although each alcoholic group showed significant bilateral volume deficits of the anterior hippocampus and frontal-parietal and temporal gray matter, relative to controls, the seizure group had significantly smaller temporal lobe white matter volumes than either the control or the seizure-free groups; the latter two groups did not differ from each other. Both alcoholic groups, however, had white matter volume deficits in the frontal-parietal region. Thus, the seizure group accounted for the white matter volume deficits in the temporal lobe previously reported in the full sample of alcoholics. It seems, then, that reduced white matter volume in the temporal lobes may be either a risk factor for or sequela of alcohol withdrawal seizures.     

A practical review of laser-assisted hair removal using the Q-switched Nd:YAG, long-pulsed ruby, and long-pulsed alexandrite lasers

BACKGROUND: The recent development of numerous laser-assisted hair removal techniques has produced confusion in the field of cutaneous laser surgery. OBJECTIVES: A systematic review of the hair removal laser systems currently available is attempted. Appropriate patient selection, treatment protocols, and discussion of each system's advantages, disadvantages, and complications is provided. CONCLUSIONS: Techniques involving the use of selective Q-switched Nd:YAG and long-pulsed alexandrite and ruby laser systems provide a significant delay in hair growth. With further technologic advances and understanding of proper treatment parameters and intervals, it is expected that permanent hair removal may eventually be possible.