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991.
Selective breeding for high and low alcohol consumption led to the establishment of alcohol-preferring (P) and alcohol-nonpreferring (NP) rat lines that differ greatly in their alcohol consumption. These lines were inbred and F2 intercross progenies were generated to detect quantitative trait loci (QTLs) influencing alcohol consumption. A QTL on chromosome 4 was identified with a maximum lod score of 8.6. This QTL acts in an additive fashion and accounts for 11% of the total phenotypic variability and approximately one-third of the genetic variability. Neuropeptide Y, an endogenous anxiolytic and neuromodulator, has been mapped to this same region of chromosome 4. This study is an advance in genome analyses, demonstrating that crosses between divergent, selectively bred rat lines can be used to identify QTLs. Localization of a gene influencing alcohol consumption may have important implications for the etiology of alcohol abuse and alcoholism in humans.  相似文献   
992.
An investigation of the degree of atomic short range order (ASRO) in alloys of palladium with scandium, dysprosium, titanium and manganese has been made using X-ray and neutron diffraction. The feasibility of performing such experiments is first discussed and following this, a number of alloys with different compositions and heat treatments have been examined. Measurable ASRO has been observed only in the most favourable cases Pd0.86Ti0.14 and Pd0.85Mn0.l5. The ASRO parameters have been determined for these examples and the form of the ASRO observed discussed in relation to long-range ordered phases.[/p]  相似文献   
993.
As a part of a study of nuclear radiation effects on shipboard electronic equipment, a large number of commonly used transistor types have been irradiated in similated transit radiation fields. A wide range was observed in the amount of radiation induced effects on gain and reverse leakage current, even within a group of one type of transistor. In general, only temporary changes were observed, with silicon types exhibiting smaller changes than the germanium units. For germanium types, reverse leakage current changed by a factor of 10-20 for some units while gain changed by a factor of 2 or less, with the change persisting in some types.  相似文献   
994.
MOSFET transistors may be fabricated with a variety of channel geometries. The trapezoidal shape for the gate provides useful IV characteristics. Channel probes are diffused for sensing Hall voltages developed across the device channel. This paper matches experimental and theoretical results for trapezoidal-gate, p-channel, enhancement-mode MOSFET devices. A nonparabolic variation of drain current with gate bias is observed. An optimum gate bias for maximum magnetic sensitivity is obtained for MAGFETs.Devices are fabricated with substrates oriented along the (100) and (111) crystallographic planes. A mobility variation with gage bias is required to accurately match the experimental measurements.  相似文献   
995.
Experimental study of electric suspension for microbearings   总被引:1,自引:0,他引:1  
Electric suspension bearings with open-loop stability have been proposed as a solution to the problem of surface contact friction resulting from the instability of rotors in micromotors. The proposed electric suspension is an open-loop stable system, which does not require the use of feedback sensors and controllers. A proof of concept experiment of the electric suspension is reported in this work. The experiment consists of levitating and holding a small flat plate in a stable equilibrium under a stator using the electric suspension design. The open-loop stability of the electric suspension is confirmed by photographing the gap between the suspended plate and the stator seen through a microscope. In addition, a gap measurement scheme based on a reflective sensor technique is implemented as a second means to verify stable levitation. The electric suspension is greatly compatible with small scale devices and systems and can be utilized to develop frictionless microactuators  相似文献   
996.
997.
Selective detection of glycopeptides on ion trap mass spectrometers   总被引:1,自引:0,他引:1  
Generation of carbohydrate-specific marker ions during LC-ESMS of digested glycoproteins has been demonstrated to be a highly selective and sensitive approach for detection of glycopeptides. In principle, any mass spectrometer can produce and selectively detect carbohydrate marker ions provided that the instrument is capable of collisional excitation in the region prior to the first mass analyzer sufficient to form abundant oxonium ions. This approach has yet to be demonstrated on 3D ion trap mass spectrometers, which have become widely used for proteomic applications. Here we report the successful development and optimization of carbohydrate marker ion detection on a LCQ Deca 3D ion trap utilizing this scan function. Human alpha-1 acid glycoprotein and a therapeutic monoclonal antibody were chosen to illustrate this methodology. Marker ion detection during LC-ESMS facilitated collection of glycopeptide-containing fractions. Analysis of the glycopeptides in these fractions by MS identified the specific glycosylation sites and enabled the prediction of the family of glycoforms at each attachment site. Using these optimized conditions, marker ion detection and glycopeptide analysis could be achieved with as little as 10 pmol of a glycoprotein.  相似文献   
998.
999.
1000.
Magnetic resonance imaging (MRI) with navigating techniques based on consecutive breath-holds demand a level of respiratory control that is often beyond the capability of patients with lung disease. The objectives of this investigation were to develop and evaluate a navigating technique for lung MRI that does not rely on patient cooperation. Navigating techniques were implemented at 0.5 T using conventional imaging techniques of short echo-time and imaging during normal breathing in the diastolic phase of the cardiac cycle. A column of spins, orthogonal to the diaphragm, was excited both immediately before and after the imaging segment. These signals were processed in real time to provide the position of the lung-diaphragm interface. An imaging segment was considered correctly acquired only when the interface position was within the acceptance window both before and after the acquisition of the segment. A distribution of lung-diaphragm interface positions obtained during normal respiration was employed to define the acceptance window. In the case of multislice techniques, the position of the lung-diaphragm interface immediately before the imaging segment was also employed to decide which phase-encoding step to acquire next, therefore reducting the apparent frequency of the respiratory motion. A distribution of interface position, updated in real time, served as a reference for the allocation of phase-encoding steps according to diaphragm position. The lung images obtained represent a significant advance in image quality, improving further the ability of MR to detect and monitor pulmonary disease. Motion artifacts were reduced, and images reliably demonstrated smaller vessels, which are not normally visible without navigation.  相似文献   
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