A Simple Circuit to Reduce the Input Capacitance of Microelectrode Amplifiers

There are several specialized applications which require amplifiers with very low input capacitance. Two field effect transistors (FET's) can be cascaded in a source follower configuration to drive the drain of the input FET. The cascaded source follower provides at least an order of magnitude decrease in input capacitance. The cascaded source follower can be added to existing amplifiers or incorporated into new amplifier design with relatively little difficulty.     

The relapse situation appraisal questionnaire: Initial psychometric characteristics and validation.

Relatively few studies have examined the role of cognitive appraisal in the process of addictive relapse. This investigation was undertaken to develop a measure of primary appraisal in situations involving a high risk for cocaine relapse. The development and psychometric properties of the Relapse Situation Appraisal Questionnaire (RSAQ) are described. The RSAQ was administered to 114 adult cocaine abusers. Participants rated their appraisal of 2 hypothetical relapse risk situations. A principal-components analysis yielded a single component solution consisting of the same 26 items for the 2 situations, both involving high internal consistency. Analyses demonstrated construct, predictive, and discriminant validity. This study provides initial evidence for the psychometric validity of the RSAQ. Results support the role of primary appraisal of high-risk situations in the process of addictive relapse. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of sex and gonadal hormones on lipid metabolism in essential fatty acid-deficient rats

Previous work has shown differences between male and female rats in their ability a) to mobilize linoleic acid from adipose tissue when the supply is limited; b) to maintain higher levels of circulating and liver arachidonic acid when dietary linoleic acid is limited; c) to prevent accumulation of cholesteryl ester (CE) in the liver; and d) to increase the proportions of polyunsaturated fatty acids (PUFA) in their plasma lecithins. Recent studies are reviewed which show that a) essential fatty acid (EFA)-deficient rats exhibit the same kinds of sex differences as do rats on complete diets; b) these differences are mediated or at least influenced by estrogen; c) some of the differences may be attributed to differences in body size which result in less need for PUFA in structural phospholipid (PL); d) the rate of conversion of linoleic to arachidonic acid may differ under certain experimental conditions; and e) female rats have higher proportions of stearic and arachidonic acids in their liver lecithins than do males, which may relate to their higher rate of lecithin synthesis via methylation of phosphatidyl-ethanolamine. Presented at the symposium on essential fatty acids in honor of George O. Burr, AOCS Meeting, Loss Angeles, April 1968.     

Design of a novel MRI compatible manipulator for image guided prostate interventions

This paper reports a novel remotely actuated manipulator for access to prostate tissue under magnetic resonance imaging guidance (APT-MRI) device, designed for use in a standard high-field MRI scanner. The device provides three-dimensional MRI guided needle placement with millimeter accuracy under physician control. Procedures enabled by this device include MRI guided needle biopsy, fiducial marker placements, and therapy delivery. Its compact size allows for use in both standard cylindrical and open configuration MRI scanners. Preliminary in vivo canine experiments and first clinical trials are reported.     

Determination of phosphorus-, copper-, and zinc-containing human brain proteins by LA-ICPMS and MALDI-FTICR-MS

Human brain proteins containing phosphorus, copper, and zinc were detected directly in protein spots in gels of a human brain sample after separation by two-dimensional gel electrophoresis using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). A powerful laser ablation system with cooled laser ablation chamber was coupled to a double-focusing sector field ICPMS. The separated protein spots in 2D gels were fast screened using the optimized microanalytical LA-ICPMS technique measured at medium mass resolution with a focused laser beam (wavelength, 213 nm; diameter of laser crater, 50 mum; and laser power density, 3 x 10(9) W cm(-2)) with respect to selected three essential elements. Of 176 protein spots in 2D gel from a human brain sample, phosphorus, copper, and zinc were detected in 31, 43, and 49 protein spots, respectively. For the first time, uranium as a naturally occurring radioactive element was found in 20 selected protein spots. The detection limits for P, S, Cu, Zn and U were determined in singular protein spots with 0.0013, 1.29, 0.029, 0.063, and 0.000 01 mg g(-1), respectively. A combination of LA-ICPMS with matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR-MS) was applied for the identification of selected protein spots from human brain protein separated by 2D gel electrophoresis. Combining MALDI-FTICR-MS for the structure analysis of metal- and phosphorus-containing human brain proteins with LA-ICPMS, the direct analysis of heteroelements on separated proteins in 2D gels can be performed. For quantification of analytical LA-ICPMS data, the number of sulfur atoms per protein (and following the sulfur concentration) determined by MALDI-FTICR-MS was used for internal standardization. From the known sulfur concentration in protein, the concentration of other heteroelements was calculated. In addition, the number of phosphorylation and the phosphorylation sites of phosphorylated proteins in the human brain sample detected by LA-ICPMS were determined by MALDI-FTICR-MS. This technique allows the study of posttranslational modifications in human brain proteins.     

Fabrication of metallic nanodots in large-area arrays by mold-to-mold cross imprinting (MTMCI)

We have developed a mold-to-mold cross imprint (MTMCI) process, which redefines an imprint mold with another imprint mold. By performing MTMCI on two identical imprint molds with silicon spacer nanowires in a perpendicular arrangement, we fabricated a large array of sub-30-nm silicon nanopillars. Large-area arrays of Pt dots are then produced using nanoimprint lithography with the silicon nanopillar mold.     

Effect of dietary cholesterol on bile-acid composition of gall bladder bile from guinea pigs

The composition of gall bladder bile acids from control and cholesterol-fed, anemic guinea pigs was analyzed by thinlayer-chromatographic and colorimetric techniques. In both control and cholesterol-fed animals, the gall bladder bile acids constituted about one third of the total bile solids. The main component of the bile acids of both groups of animals was chenodexycholic acid, which was predominantly conjugated with glycine. No cholic acid was present although this is the main bile acid in most mammals. The major difference in bile composition between control and cholesterol-fed animals was the conjugation pattern of chenodeoxycholic acid. The ratio of glycochenodeoxycholic to taurochenode-oxycholic acid was high, 6.4, for control animals, and decreased to 2.4 for the cholesterol-fed, anemic animals. Impaired liver function, limited availability of glycine, and greater efficiency of taurocholanic acids for the disposal of excess cholesterol may be involved in the mechanism for this phenomenon. Material in this paper has been submitted in partial satisfaction of the requirements for the degree of Master of Science in Nutition in the Graduate Division of the University of California, Berkeley. A portion of this material was presented at the 7th International Congress of Biochemistry in Tokyo, Japan, August, 1967.     

A neutron irradiation facility featuring cryogenic temperatures and dedicated to Large Hadron Collider detector design

The SARA facility at Grenoble provides the possibility to carry out neutron irradiation studies at both cryogenic and room temperatures, and permits at the same time to measure on-line the deterioration of the electronic performance of the tested circuits. The cryogenic vessel consists of a 101 liquid argon cryostat placed behind the neutron source. A TOF technique was used to measure the neutron energy spectrum produced by the collision of a 20 MeV deuteron beam on a thick Be target. Alanine and thermoluminescent dosimeters were used to determine the neutron and photon doses. The results show that the neutron and the gamma dose components are about 78% and 22%, respectively. The angular distribution of the dose was also measured.     

Thermogravimetric/mass spectrometric characterization of the thermal decomposition of (4-O-methyl-D-glucurono)-D-xylan

A thermogravimetric/mass spectrometric (TG/MS) system was used to characterize the thermolysis reactions of (4-O-methyl-D -glucurono)-D -xylan. The mass spectrometric peaks, measured as function of time, were attributed to water, methanol, carbon monoxide, carbon dioxide, formaldehyde, formic acid, acetic acid, acetone, acrolein, 2-furaldehyde, and 3-hydroxy-2-penteno-1,5-lactone. The time derivative of the thermogravimetric curve (DTG) consisted of two partially overlapping peaks, indicating a multistep mechanism. The mass spectrometric intensities of the peaks assigned to methanol and 2-furaldehyde coincided with the first DTG peak, suggesting that the first DTG peak represents both dehydration and fragmentation pathways. Methanol, water, formyl group, and carbon dioxide contributed to both of the DTG peaks. This indicates that the dehydration, decarboxylation, and decarbonylation took place in two steps. The compounds observed only in the second DTG peak and later (acetone, formic acid, formaldehyde, acrolein, acetic acid, and 3-hydroxy-2-penteno-1,5-lactone) are probably products of reactions which occur after the collapse of the original polysaccharide structure.