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Biomedical subjects

S Granick

Publications and source records attributed to S Granick.

At least 19 recordsLinked to original sources
PubMed2002

Confinement-induced differences between dielectric normal modes and segmental modes of an ion-conducting polymer.

Dielectric measurement in the range 0.1 Hz to 1 MHz were used to study the motions of polymers and ions in an ion-conducting polymer, polypropylene oxide containing small quantities (on the order of 1%) of lithium ions (LiClO(4)), confined as a sandwich of uniform thickness between parallel insulating mica surfaces. In the dielectric loss spectrum, we observed three peaks; they originated from the normal mode of the polymer, segmental mode of the polymer, and ion motions. With decreasing film thickness, the peak frequencies corresponding to the normal mode and ion motion shifted to lower frequencies, indicating retardation due to confinement above 30 nm. This was accompanied by diminished intensity of the dielectric normal-mode relaxation, suggesting that confinement diminished the fluctuations of the end-to-end vector of the chain dipole in the direction between the confining surfaces. On the contrary, the segmental mode was not affected at that thickness. Finally, significant retardation of the segmental mode was observed only for the thinnest film (14 nm). The different dynamical modes of the polymer (segmental and slowest normal modes) respond with different thickness and temperature dependence to confinement.

Journal Article↗
PubMed2001

Viscosity of interfacial water.

The effective shear viscosity and frequency-dependent dynamic oscillatory shear spectra of water containing monovalent or divalent ions (ionic strength 25 mM), confined between mica crystals at 1-2 water molecules thickness, oscillated with twist angle with the period expected for the pseudohexagonal surface lattice. The effective viscosity varied by orders of magnitude as the twist angle was changed. Confinement appeared to imprint lateral spatial correlation on the ultrathin liquid, the more so the better the confining lattices were aligned, but the oft-proposed "ice structure" was not observed dynamically.

Viscosity↗
PubMed2001

Rate-dependent slip of Newtonian liquid at smooth surfaces.

Newtonian fluids were placed between molecularly smooth surfaces whose spacing was vibrated at spacings where the fluid responded as a continuum. Hydrodynamic forces agreed with predictions from the no-slip boundary condition only provided that flow rate (peak velocity normalized by spacing) was low, but implied partial slip when it exceeded a critical level, different in different systems, correlated with contact angle (surface wettability). With increasing flow rate and partially wetted surfaces, hydrodynamic forces became up to 2-4 orders of magnitude less than expected by assuming the no-slip boundary condition that is commonly stated in textbooks.

Journal Article↗
PubMed1996

The relationships of substance abuse to illegal and violent behavior, in a community sample of young adult African American men and women (gender differences).

In a longitudinal study of an African American young adult community sample (N = 380), prospective data on lifetime substance use/abuse from childhood up to age 24 were used as control variables in analyses to predict illegal and violent behavior during the ensuing 2 1/2-year period. Frequent earlier use of drugs predicted subsequent violent behavior for both men and women. Frequency of earlier use of alcohol predicted subsequent violent behavior for men but not for women. A weaker relationship was found between degree of psychopathology and degree of engaging in either illegal or violent behavior than between degree of psychopathology and degree of substance use/abuse. Comorbidity (the combination of earlier use/abuse of drugs with earlier psychopathology) was a stronger predictor, for women than for men, of later illegal and violent behavior.

Adult↗
PubMed1996

The consequences of drug use/abuse for vocational career: a longitudinal study of a male urban African-American sample.

This report is from a longitudinal study of a community sample of African-American males (N = 197) on the relationship of the degree of earlier substance use/abuse up to average age 24, to vocational performance (employment and occupational level) 2 1/2 years later (at average age 26 1/2). The statistical analyses included numerous control variables developed from prospective data of the National Collaborative Perinatal Project, on the subjects and on their families from the subjects' birth to age 7, and from their school behavior and academic performance up to age 16, which may have influenced their vocational-occupational behavior during early adulthood. It was found that greater earlier marijuana use and greater earlier alcohol use predicted, to a significant degree, poorer occupational performance.

Adult↗
PubMed1995

Gender differences in early life risk factors for substance use/abuse: a study of an African-American sample.

Gender differences in risk and protective factors for substance use/abuse in early adulthood were studied. Comprehensive systematic data on African-American males (N = 318) and females (N = 322), from birth to 7 years of age, were available from the National Collaborative Perinatal Study. These subjects were retrieved for assessment at average age 24. There are more differences between males and females than there are similarities in regard to the early childhood variables that predict substance use in early adulthood. However, high activity and intensity of response during infancy (measured at 8 months of age) was found to predict later substance use for both males and females. This type of behavior is considered by use to be a trait of temperament and to suggest the possibility of a genetic predisposition. More risk factors were found for female than for males. The risk factors for females were primarily of two types: 1) Related to experiences with mother and with the family environment; and 2) Poor levels of intellectual functioning and academic performance, and abnormal mental status.

Adult↗
PubMed1984

Mental status and memory assessment as predictors of dementia.

Mental status instruments that have been used in assessing the cognitive status of elderly adults have focused primarily on orientation and remote memory. In this study the Extended Mental Status Questionnaire (EMSQ) and the Philadelphia Geriatric Center (PGC) Delayed Memory Test were found to be the best combined predictors of clinical judgment of senile dementia among a multidisciplinary set of variables. The EMSQ differentiated patients with moderate/severe dementia from patients classified as non- or mildly demented but incorrectly classified all mildly demented patients. With the addition of the PGC Delayed Memory Test, 75% of the mildly demented patients were classified correctly. The PGC Delayed Memory Test, therefore, appears to be useful in identifying patients in the early stages of cognitive decline.

Aged↗