Saccadic system functioning among schizophrenia patients and their first-degree biological relatives.

In Study 1, 30 schizophrenia Ss and 27 nonpsychiatric comparison Ss were presented with a fixation task, a visually guided reflexive saccade (prosaccade) task, a predictive tracking task (0.4-Hz square wave), and an antisaccade task. The 2 groups did not differ on either the fixation or prosaccade tasks. Schizophrenia Ss had an increased number of errors on the antisaccade task and had decreased rightward visually guided saccade amplitudes during the predictive tracking task. In Study 2, 13 psychiatric comparison Ss and 32 1st-degree biological relatives of the schizophrenia Ss were compared with the schizophrenia Ss and a larger and older sample of nonpsychiatric Ss (n?=?33) on the predictive tracking and antisaccade tasks. The groups did not differ on predictive saccadic tracking. The schizophrenia Ss and their 1st-degree biological relatives made more errors on the antisaccade task than both the nonpsychiatric and psychiatric comparison groups (who did not significantly differ). Results are consistent with the notion that dysfunction of dorsolateral prefrontal cortex, caudate nucleus, or both is related to liability for schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cigarette smoking and submaximal exercise test duration in a biracial population of young adults: the CARDIA study

Symptom-limited, graded exercise treadmill testing was performed by 4,968 white and black adults, ages 18-30 yr, during the baseline examination for the Coronary Artery Risk Development in Young Adults (CARDIA) study. Compared with nonsmokers, the mean exercise test duration of smokers was 29-64 s shorter depending on race/gender group (all P < 0.001), but mean duration to heart rate 130 (beats.min-1) ranged from 20-50 s longer (P < 0.05). In each race/gender group, test duration to heart rates up to 150 was 15-35 s longer (P < 0.05) in smokers than in nonsmokers after adjustment for age, sum of skinfolds, hemoglobin, and physical activity score. The mean maximum heart rate was lower in smokers than in nonsmokers (difference ranging from 6.7 beats.min-1 in white men to 11.2 beats.min-1 lower in black women, P < 0.001), although maximum rating of perceived exertion was nearly identical in smokers and nonsmokers. Chronic smoking appears to blunt the heart rate response to exercise, so that exercise duration to submaximal heart rates is increased even though maximal performance is impaired. This may result from downloading of beta-receptors caused by smoking. Smoking status should be considered in the evaluation of physical fitness data utilizing submaximal test protocols, or else the fitness of smokers relative to nonsmokers is likely to be overestimated.     

Low total serum cholesterol and intracerebral hemorrhagic stroke: is the association confined to elderly men? The Kaiser Permanente Medical Care Program

BACKGROUND AND PURPOSE: Epidemiological studies indicate a higher incidence of intracerebral (but not subarachnoid) hemorrhagic stroke among persons with low total serum cholesterol levels. This report further examines the prospective relationship of total serum cholesterol with subsequent intracerebral hemorrhage in a large, well-defined population. METHODS: The cohort included 61756 enrollees in a health plan from the San Francisco-Oakland metropolitan area (46% men, 63% white), aged 40 to 89 years and free of cardiovascular disease at baseline. Sixteen-year incidence of combined nonfatal and fatal intracerebral hemorrhagic stroke (International Classification of Diseases [ICD], 8th revision, code 431, or ICD, 9th revision, codes 431 and 432) was investigated in relation to serum cholesterol measured in multiphasic health checkups made in 1977 through 1985. Intracerebral hemorrhagic events were ascertained using hospital discharge records and as underlying cause of death by the California Mortality Linkage Information System. RESULTS: From 1978 through 1993 (average of 10.7 years), there were 386 events (201 in men, 29% fatal; 185 in women, 42% fatal). By multivariate proportional hazards life-table regression analysis, serum cholesterol level below the sex-specific 10th percentile (< 4.62 mmol/L [178 mg/dL] in men), compared with higher cholesterol level, was associated with a significantly increased risk of intracerebral hemorrhage in men aged 65 years or older (relative risk, 2.7; 95% confidence interval, 1.4 to 5.0). An excess risk was also observed among elderly women at the lowest cholesterol range, but a chance finding could not be ruled out. No relationship was seen among men or women aged 40 to 64, and no statistical interaction of low serum cholesterol with hypertension was found in either sex. CONCLUSIONS: In these data, the association between low serum cholesterol level and intracerebral hemorrhage was confined to elderly men.     

Interpretation of Compositional Patterns Found by Quantitative Energy Dispersive X-ray Analysis for Cement Paste Constituents.

More than 200 individual particles within a portland scement paste were morphologically categorized by backscatter SEM and analyzed systematically by EDXA. Nearly all of the analyses fall either in a dense cluster around a mean C-S-H gel composition or along tie lines connecting this composition to theoretical compositions for calcium hydroxide, monosulfate, ettringite, and ferrite. "Phenograin" C-S-H gel (formed as a direct replacement product within large cement grains) contains small amounts of Al, Fe, and S, but otherwise shows almost negligible compositional variation. In contrast, smaller groundmass particles and shells of gapped phenograins show a slightly differentc S-H gel composition. Some of these, despite being morphologically homogeneous, show compositions falling along tie lines to the other recognized phases. This is attributed to extensive occurrence of intimate mixtures of C-S-H gel with the other components below the scale of SEM observation. Ionic substitutions appear to be minor except for the monosulfate and ettringite components in such mixtures. These show a variable but usually high deficiency in the sulfate content.     

Gaze tutor: A gaze-reactive intelligent tutoring system

We developed an intelligent tutoring system (ITS) that aims to promote engagement and learning by dynamically detecting and responding to students' boredom and disengagement. The tutor uses a commercial eye tracker to monitor a student's gaze patterns and identify when the student is bored, disengaged, or is zoning out. The tutor then attempts to reengage the student with dialog moves that direct the student to reorient his or her attentional patterns towards the animated pedagogical agent embodying the tutor. We evaluated the efficacy of the gaze-reactive tutor in promoting learning, motivation, and engagement in a controlled experiment where 48 students were tutored on four biology topics with both gaze-reactive and non-gaze-reactive (control condition) versions of the tutor. The results indicated that: (a) gaze-sensitive dialogs were successful in dynamically reorienting students’ attentional patterns to the important areas of the interface, (b) gaze-reactivity was effective in promoting learning gains for questions that required deep reasoning, (c) gaze-reactivity had minimal impact on students’ state motivation and on self-reported engagement, and (d) individual differences in scholastic aptitude moderated the impact of gaze-reactivity on overall learning gains. We discuss the implications of our findings, limitations, future work, and consider the possibility of using gaze-reactive ITSs in classrooms.     

A λ-unifiability test for set theory

We present a semi-decision algorithm for the unifiability of two set-theoretic formulas modulo -reduction. The algorithm is based on the approach developed by G. Huet for type theory, but requires additional measures because formulas in set theory are not all normalizable. We present the algorithm in an Ada-like pseudocode, and then prove two theorems that show the completeness and correctness of the procedure. We conclude by showing that -unification is not a complete quantifier substitution method for set theory-unlile first-order unification and first-order logic. In this respect set theory is similar to type theory (higher-order logic).This material is based upon work supported by the National Science Foundation under award number ISI-8560438. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the author and do not necessarily reflect the views of the National Science Foundation.     

The effect of the third invariant on the strength and failure of boron carbide and silicon carbide

This article presents new test data to assess the effect the third invariant has on the strength and failure of two ceramic materials: boron carbide and silicon carbide. Two experimental techniques are used: the Brazilian test that produces a biaxial state of stress, and a new technique that uses a high-pressure confinement vessel to load a specially designed dumbbell specimen in triaxial extension. The dumbbell geometry provides two important advantages over the typically used cylindrical specimen: no adhesive is required to bond the specimen to the load cell because the dumbbell geometry naturally takes the specimen into tension, and any loading asymmetries are essentially eliminated due to the axisymmetric geometry. The results show that when the stress state is on the tensile meridian the equivalent stress at failure is constant, independent of the hydrostatic pressure. The average equivalent stress at failure is for boron carbide and for silicon carbide. The Brazilian test was only performed on boron carbide and failed at , much higher than when on the tensile meridian () indicating that the effect of the third invariant is significant (because of the difference in the failure strength) and must be accounted for to accurately predict when failure will occur.     

Fate of Calcium Chloride Dissolved in Concrete Mix Water

The extent to which chloride ion incorporated in portland cement concrete as calcium chloride accelerator at the usual treatment levels remains dissolved in the pore solution was investigated. This was examined by direct analysis of pore solutions expressed from cement pastes. The chloride ion concentration of the pore solution remains high during the first day of hydration and only gradually declines. It appears that appreciable concentrations of chloride ion likely remain in solution indefinitely .     

β-Carotene transport in human lipoproteins. Comparisons with a-tocopherol

The purpose of this study was to investigate the temporal relationships of the transport of β-carotene in human lipoproteins. We administered 60 mg β-carotene with breakfast to nine fasting subjects, then blood samples were collected at intervals of up to 75 h, lipoproteins were isolated, and β-carotene was quantitated. β-Carotene concentrations in chylomicrons and very low density lipoproteins (VLDL) peaked at 6 and 9 h, respectively. Nonetheless, at all time points the majority of plasma β-carotene was contained in low density lipoproteins (LDL), while high density lipoproteins (HDL) carried a smaller portion (at 24 h, 73±8% in LDL as compared with 23±5% in HDL). In three subjects, transport of β-carotene was compred with the results of earlier studies on the transport of stereoisomers of α-tocopherol. Unlike plasmaRRR-α-tocopherol concentrations, which are maintained by the preferential incorporation ofRRR-α-tocopherol into VLDL by the liver, β-carotene increased and decreased in VLDL similarly toSRR-α-tocopherol, a stereoisomer whose concentrations are not maintained in plasma. In conclusion, β-carotene is primarily transported in the plasma in LDL, but its incorporation by the liver into lipoproteins does not appear to be enhanced.