Visual variant of Alzheimer's disease: Distinctive neuropsychological features.

A subgroup of patients with probable Alzheimer disease (AD) reported a history of isolated visual disturbances (VS) early in the course of disease, without the characteristic memory complaints. Brain imaging and neuropathologic studies indicated that this subgroup had larger involvement of visual cortical areas and relative sparing of temporal. frontal, and limbic structures compared with classic AD. Consistent with these findings, the authors hypothesized that the cognitive deficits in this subgroup would be distinctly different from those seen in more typical AD patients. The authors studied 10 probable AD patients with VS (AD&±&|S), 22 patients without VS (AD–), and 25 healthy controls with a neuropsychological test battery. Compared with AD–, AD&±&|S patients performed significantly better on tests of verbal memory and had greater impairment on tests of visuospatial skills, suggesting a distinct pattern of cognitive dysfunction consistent with metabolic and neuropathologic reports. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related changes in the lipid metabolism of Fisher 344 rats

Lipid metabolism of male Fisher 344 rats aged 2–24 months was studied. Serum and liver cholesterol levels did not display the age-related gradual increase seen in other rat strains. An increase in the serum plus liver cholesterol pool from 2 to 6 months was followed by a plateau through 18 months and then another increase at 24 months of age. The triglyceride pool increased from 2 to 6 months and then remained unchanged through 24 months of age. Cholesterol synthesis from acetate decreased 50% between 2 and 9 months and fell only slightly through 24 months of age. Assay of 3-hydroxy-3-methyl glutaryl Coenzyme A (HMG-CoA) reductase showed a similar pattern but did not decrease further after 9 months of age. Cholesterol 7α hydroxylase activity was not significantly altered by age. These age- and strain-related differences present an opportunity for a comparative study of the aging process using the parameters of lipid metabolism as indicators.     

Verbal operant conditioning of hospitalized psychiatric patients.

In Exp. I, 81 male psychiatric patients were divided into 9 subgroups according to age and length of hospitalization. Plural nouns were reinforced by positive verbal feedback. Results were: (1) least chronic Ss increased their operant rates; (2) most chronic Ss did not; and (3) there was significant interaction with respect to age and chronicity. In Exp. II, 60 schizophrenics were divided into 6 subgroups with respect to length of hospitalization and mode of reinforcement, i.e., verbal, primary, or combination. Acute-type schizophrenics responded positively to all types of reinforcement. Chronics responded only to primary reinforcement and to the combination procedure. Mode of reinforcement was a significant variable affecting operant rate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of soil freezing events in interannual patterns of stream chemistry at the Hubbard Brook Experimental Forest,New Hampshire

Soil freezing is a disturbance of the below ground environment, potentially resulting in increased losses of NO3- and surface water acidification. Here, we report the effects of soil freezing on interannual variation in stream chemistry at the Hubbard Brook Experimental Forest, New Hampshire. Data from 1970 to 1997 of soil frost depth, snow cover, precipitation, air temperature, and stream discharge and chemistry were used in a stepwise linear regression model to select the variables that best predicted deviations of annual stream concentrations from 4-year running averages. Variables quantifying soil freezing severity were selected as significant predictors of short-term fluctuations in stream K+, NO3-, Ca2+, and Mg2+ concentrations from 1970 to 1989, explaining 59 and 47% of the short-term variability in K+ and NO3-, respectively. Fine-root mortality and disturbance of root-soil-microbe interactions, with subsequent effects on decomposition and nutrient uptake, likely contributed to the mobilization of K+ and NO3- to streamwater following severe soil freezing events. The relationship between soil freezing and stream chemistry, however, weakened during the period 1990-1997. Because soil freezing has had inconsistent effects on stream chemistry during the period 1970-1997, it is unclear whether future changes in the frequency, duration, and depth of soil freezing events as the result of changes in the snow cover regime under a warmer climate will have significant impacts on the losses of NO3- and nutrient-base cations from temperate northern ecosystems.     

Simultaneous registration and activation detection for fMRI

Registration using the least-squares cost function is sensitive to the intensity fluctuations caused by the blood oxygen level dependent (BOLD) signal in functional MRI (fMRI) experiments, resulting in stimulus-correlated motion errors. These errors are severe enough to cause false-positive clusters in the activation maps of datasets acquired from 3T scanners. This paper presents a new approach to resolving the coupling between registration and activation. Instead of treating the two problems as individual steps in a sequence, they are combined into a single least-squares problem and are solved simultaneously. Robustness tests on a variety of simulated three-dimensional EPI datasets show that the stimulus-correlated motion errors are removed, resulting in a substantial decrease in false-positive and false-negative activation rates. The new method is also shown to decorrelate the motion estimates from the stimulus by testing it on different in vivo fMRI datasets acquired from two different 3T scanners.     

心电图仪设计综述

介绍了心电图仪(ECG或EKG)的基本架构及心电信号的电子测量和显示的基本原理,探讨了ECG设备的模拟前端(AFE)及信号通道对心率信号实现数字化的问题,并讨论了各种ECG应用,包括自动体外除颤仪(AED)、病人监护仪和高端诊断型ECG及其所提供的多种功能。     

The relationship between clients' expected and actual treatment duration.

Investigated the relationship of clients' expected and actual treatment duration in 148 outpatients (mean age 27 yrs) treated by 20 therapists. Data from questionnaires suggest that clients expected and attended a relatively low number of visits; these patterns were discrepant with the therapists' duration preferences. A stepwise regression analysis indicated that clients' expected number of visits was the only variable that incrementally increased the predictability of client visits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)