Transient changes in the concentration of intracellular free calcium are associated with the transduction of primary signals and the subsequent employment of Ca2+ as a second messenger in a multitude of cell types. These transients, typically monitored with the calcium-sensitive fluorescent dye Fura-2, are known to occur with a time course in the order of seconds. In order to accurately monitor such rapid changes in intracellular free calcium concentration in both single cells and simultaneously in several cells in a single field, we have developed a digital fluorescence imaging system based on a charge-coupled device (CCD) camera. We report here on the detailed kinetics of calcium increases in cultured arterial swine smooth muscle cells in response to the agonist ATP.

Adenosine Triphosphate↗

PubMedDate not supplied

The left visual hemispace bias for the perception of chimeric faces: a further test of the difficulty of discrimination hypothesis.

When people make judgments of visual-spatial forms, they generally perform better if the information is presented in their left visual hemispace (LVH), whereas for verbal material, they generally show a right visual hemispace (RVH) bias. For verbal material, the strength and direction of the effect also has been linked to task difficulty, with the bias shifting toward the RVH as task difficulty increases. Two experiments are presented that show the reverse direction of change for a nonverbal task; that is, when a nonverbal task is more difficult, the usual LVH effect shifts toward an RVH bias. Taking into account recent developments in theory and research on hemispheric differences in styles of information processing, we propose that task difficulty is related more generally to changes in processing style.

Adult↗

PubMedDate not supplied

Left-side infant holding: a test of the hemispheric arousal-attentional hypothesis.

When asked to hold a young infant in their arms, most adults hold on the left side (Harris, 1997). In a prior study, we found the same bias when we asked adults merely to imagine holding an infant in their arms (Harris, Almerigi, & Kirsch, 1999). It has been hypothesized that the left-side bias is the product of right-hemisphere arousal accompanying certain aspects of the act, causing attention to be driven to the contralateral, or left, side of personal space. Left-side holding, whether actual or imagined, thus would be consistent with the direction to which the holder's attention has been endogenously directed. We tested this hypothesis by giving 250 college students the "imagine-holding" task and then, as an independent measure of lateralized hemispheric arousal, a 34-item Chimeric Faces Test (CFT). On the "imagine" test, a significant majority reported a left-side hold, and, on the CFT, left-side holders had a significantly stronger left-hemispace bias than right-side holders, although both left- and right side holders had left-hemispace CFT biases. The results thus support the attentional-arousal hypothesis but indicate that other factors are contributing as well.

Adult↗

PubMedDate not supplied

Charge-coupled device detector: performance considerations and potential for small-field mammographic imaging applications.

The physical characteristics of a charge-coupled device (CCD) image detector were evaluated, as well as its potential as a digital imaging device for small field mammographic applications such as preoperative needle localization. The detection system is based on a 2048 x 2048 pixel CCD operated in 1024 x 1024 mode. The CCD was optically coupled to an intensifying screen via a lens, without intermediate intensification. The thermal noise was suppressed to 0.15 electrons pixel-1s-1 by cooling the CCD with liquid nitrogen. The dominant source of noise was attributed to the on-chip amplifier during the readout process that was performed at 50,000 pixels s-1. The measured readout noise level was 15 electrons per pixel. The low-noise characteristics of this CCD prototype detector produced encouraging results under conditions simulating mammography, with a signal level close to one electron per pixel for each detected x ray. The mean glandular dose to the breast, based on the entrance exposure measured from a standard mammographic phantom would be 1.52 mGy (152 mrad). The ultimate spatial resolution of the system was approximately 8 cycles/mm but it was limited to about 5 cycles/mm when operated in the 1024 x 1024 imaging mode. Other physical characteristics of the system such as optical coupling efficiency, exposure response, and signal-to-noise ratio were evaluated. The results of this study suggest that the use of a scientific-grade CCD allows for very good low-contrast discrimination and moderate spatial resolution under conditions simulating mammography, but the current prototype is limited to a 9 x 9-cm2 field of view.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗

PubMedDate not supplied

Side preference in adults for holding infants: contributions of sex and handedness in a test of imagination.

Five hundred one right-handers (150 men, 351 women) and 53 left-handers (15 men, 38 women) were asked to imagine holding a young infant in their arms. Right-handers reported significant left-side biases--in 68% of the men and 73% of the women. For left-handers, side preferences were weaker, the left-side bias dropping to 47% for men and 60% for women, with neither figure different from chance. The results are discussed in the context of theory and research on the functional neuroanatomy of attention, emotional arousal, and the generation, maintenance, and manipulation of mental images.

Adult↗

PubMedDate not supplied

Handedness and footedness in Korean college students.

This study was conducted to obtain normative data on foot preference and to compare footedness and handedness in a large sample (N = 866) of college students in Korea, where left-hand use for writing and other public acts is severely restricted (Kang & Harris, 1993). Based on scores from Korean-language versions of the Edinburgh Handedness Inventory (EHI; Oldfield, 1971) and the Waterloo Footedness Questionnaire Revised (WFQ-R; Elias, Bryden, & Bulman-Fleming, 1988), 11% of the subjects were left-footed but only 4.2% as left-handed. A significantly higher percentage of left-handers than right-handers showed crossed lateral preference, that is, for preference of the opposite-side foot. Of the left-handers with crossed preference, the majority were inconsistent left-handers (ILH; Peters & Servos, 1989), whereas most of those with uncrossed preference were consistent left-handers (CLH). Factor analysis of the EHI and WFQ-R revealed 2 handedness factors and 2 footedness factors. The footedness factors for skilled unipedal actions and for balancing-stabilizing varied in direction, strength, and relation to handedness in mixed-footers and left-handers, consistent with the possibility that the division of footedness into these categories might be neuropsychologically meaningful.

Adult↗