Physical Conditions of Fast Glacier Flow: 3. Seasonally-Evolving Ice Deformation on Store Glacier, West Greenland

Temporal variations in ice sheet flow directly impact the internal structure within ice sheets through englacial deformation. Large-scale changes in the vertical stratigraphy within ice sheets have been previously conducted on centennial to millennial timescales; however, intra-annual changes in the morphology of internal layers have yet to be explored. Over a period of 2 years, we use autonomous phase-sensitive radio-echo sounding to track the daily displacement of internal layers on Store Glacier, West Greenland, to millimeter accuracy. At a site located ∼30 km from the calving terminus, where the ice is ∼600 m thick and flows at ∼700 m/a, we measure distinct seasonal variations in vertical velocities and vertical strain rates over a 2-year period. Prior to the melt season (March-June), we observe increasingly nonlinear englacial deformation with negative vertical strain rates (i.e., strain thinning) in the upper half of the ice column of approximately -0.03 a-1, whereas the ice below thickens under vertical strain reaching up to +0.16 a-1. Early in the melt season (June-July), vertical thinning gradually ceases as the glacier increasingly thickens. During late summer to midwinter (August-February), vertical thickening occurs linearly throughout the entire ice column, with strain rates averaging 0.016 a-1. We show that these complex variations are unrelated to topographic setting and localized basal slip and hypothesize that this seasonality is driven by far-field perturbations in the glacier's force balance, in this case generated by variations in basal hydrology near the glacier's terminus and propagated tens of kilometers upstream through transient basal lubrication longitudinal coupling.

Rapid expansion from supercritical to aqueous solution to produce submicron suspensions of water-insoluble drugs

Stable suspensions of submicron particles of cyclosporine, a water-insoluble drug, have been produced by rapid expansion from supercritical to aqueous solution (RESAS). To minimize growth of the cyclosporine particles, which would otherwise occur in the free jet expansion, the solution was sprayed into an aqueous Tween-80 (Polysorbate-80) solution. Steric stabilization by the surfactant impedes particle growth and agglomeration. The particles were an order of magnitude smaller than those produced by RESS into air without the surfactant solution. Concentrations as high as 38 mg/mL for 400-700 nm particles were achieved in a 5.0% (w/w) Tween-80 solution.

Encapsulation of lysozyme in a biodegradable polymer by precipitation with a vapor-over-liquid antisolvent

Lysozyme was encapsulated in biodegradable polymer microspheres which were precipitated from an organic solution by spraying the solution into carbon dioxide. The polymer, either poly(l-lactide) (l-PLA) or poly(DL-lactide-co-glycolide) (PGLA), in dichloromethane solution with suspended lysozyme was sprayed into a CO2 vapor phase through a capillary nozzle to form droplets which solidified after falling into a CO2 liquid phase. By delaying precipitation in the vapor phase, the primary particles became sufficiently large, from 5 to 70 microm, such that they could encapsulate the lysozyme. At an optimal temperature of -20 degrees C, the polymer solution mixed rapidly with CO2, and the precipitated primary particles were sufficiently hard such that agglomeration was markedly reduced compared with higher temperatures. More uniform particles were formed by flowing CO2 at high velocity in a coaxial nozzle to mix the droplets at the CO2 vapor-liquid interface. This process offers a means to produce encapsulated proteins in poly(DL-lactide-co-glycolide) microspheres without earlier limitations of massive polymer agglomeration and limited protein solubility in organic solvents.

Heights of U.S. Presidents: a trend analysis for 1948-1996

A Mann Trend Test yielded a trend in increased height for 10 U.S. Presidents from 1948-1996, consistent with previous findings that height is a heuristic for dominance.

Body mass indexes and historical ratings of U.S. presidents: 1948-1984

U.S. Presidents from 1948–1984 whose body mass indexes were greater than 25 received higher ratings from historians in the Murray-Blessing Poll than their smaller peers as is consistent with previous research on size and perceived leadership.

A cervical manikin procedure for chiropractic skills development

OBJECTIVE

To determine whether chiropractic students can effectively acquire adjustive skills for the cervical spine by utilizing a Thrust in Motion Cervical (TMC) manikin and to evaluate its value as a teaching aid. A pilot study was formulated and incorporated into the skills tutorial program at Macquarie University. Centre for Chiropractic in Sydney, Australia.

DESIGN AND SETTING

A prospective study was performed on chiropractic students with no prior experience in performing spinal adjustments.

SUBJECTS

Twenty subjects were selected randomly from a population of 75 students about to commence their 4th-yr Master's of Chiropractic program.

INTERVENTION

Students who formed the experimental group (n = 6) did not perform any thrusting maneuvers on human subjects while practicing Diversified chiropractic cervical spinal techniques. They practiced the adjustive thrust only on the TMC manikin. The control group (n = 14) learned in the established "hands-on" approach, performing thrusting maneuvers on fellow student subjects. Both groups were supervised, taught and examined in an otherwise identical fashion.

RESULTS

The data indicate there is no significant difference between the examination scores of the student group that practiced on the TMC manikin (average, 2.17 points) compared with the controls (2.13 points), with a confidence interval at p = .985, assuming that 0.5 marks is clinically important in these examination results. Interexam reliability was acceptable (Pearson's r = .73) for both experimental and control examination performances.

CONCLUSION

The null hypothesis is accepted, and no significant difference in student examination performance was found between those who learned thrusting on the manikin alone and those who learned on fellow students. Further, for the first time, a manikin has been shown to be effective in teaching chiropractic skills. The implications of the TMC manikin procedure will revolutionize the acquisition of motor learning skills that are essential for chiropractic skills training.

Homicide rates among Native American children: the status integration hypothesis

An analysis of data for all twelve U.S. Indian Health Service areas yielded a positive Spearman's correlation coefficient for the percentage of Native American females in the labor force and the homicide rates per 100,000 population for Native American children (1 month to 14 years), supporting the hypothesis of status integration.

Height and perceived competence of US presidents

The 4 “great” U.S. Presidents, as listed in the 1982 Murray-Blessing Poll, were significantly taller ( M = 74.63 in.) than the 5 considered “failures” ( M = 70.80 in.), consistent with previous research on height and status.

Hitler's psychopathology: advantages and limitations of psychohistorical assessments of personality

Psychohistorians have uncovered a wealth of evidence suggesting that Hitler's psychopathology became projected and rationalized as social policy. Despite this cumulative evidence, no specific diagnosis has been generally accepted. The strengths and weaknesses of psychohistorical research and the ethical responsibilities involved in its use are discussed.

Azabicyclic indole esters as potent 5-HT4 receptor antagonists

The synthesis of a series of azabicyclic indole esters is described and their potency reported as 5-HT4 receptor antagonists. Optimization of the most potent compound (19) by preparing the corresponding oxazino[3,2-a]indole ester afforded 34, which had a pIC50 of 9.5 in the guinea pig distal colon longitudinal muscle myenteric plexus preparation.

In vivo model of cartilage degradation--effects of a matrix metalloproteinase inhibitor

OBJECTIVES

To develop a model of cartilage degradation that (i) enables the testing of synthetic, small molecular weight matrix metalloproteinase (MMP) inhibitors as agents to prevent cartilage erosion, (ii) permits the direct assay of the principal constituents of the extracellular matrix (collagen and proteoglycan) in both the non-calcified articular cartilage and the calcified cartilage compartments, and (iii) is mediated by a chronic, granulomatous tissue that closely apposes intact articular cartilage, and in this respect resembles the pannus-cartilage junction of rheumatoid arthritis.

METHODS

Femoral head cartilage was obtained from donor rats, wrapped in cotton and implanted subcutaneously into recipient animals. After a two stage papain digestion procedure, the proteoglycan and collagen contents were measured by assaying for glycosaminoglycans and hydroxyproline, respectively, in both the non-calcified cartilage that comprises the articular surface layer and the calcified cartilage compartment. The incorporation in vitro of [35S]-sulphate into glycosaminoglycans was assayed as a measure of proteoglycan biosynthesis. An osmotic minipump was cannulated to the implanted femoral head cartilage and synthetic MMP inhibitors (MI-1 and MI-2) were infused continuously over a 14 day period.

RESULTS

The implanted, cotton wrapped femoral head cartilages provoked a granulomatous response that resulted in the removal of collagen and proteoglycan from the cartilage matrix. The removal of proteoglycan and collagen was exclusively from the non-calcified articular cartilage, whereas the proteoglycan and collagen content of the calcified compartment increased during the experiments. MI-1 reproducibly reduced the degradation of proteoglycan and collagen in implanted femoral head cartilage.

CONCLUSIONS

We have described an in vivo model of cartilage degradation that permits the measurement of proteoglycan and collagen in both non-calcified articular cartilage and calcified cartilage compartments. The model can be used to test the effects of agents of unknown systemic bioavailability and pharmacokinetic profile by infusing them directly to the site of cartilage degradation. The removal of cartilage extracellular matrix by granulomatous tissue was inhibited by an MMP inhibitor, thus proving the involvement of this family of proteinases in cartilage catabolism in this model.

Suicide and social status among Native Americans

An analysis of unpublished secondary data on suicide rates for U.S. Indian Health Service areas did not provide cross-cultural support for the social control hypothesis that high-status categories have higher suicide rates than low-status categories.

Locus of control, depression, and anger among African-Americans

Subjects, 98 African-American college students, were given a measure of belief in locus of control, a self-report measure of depression, and three scales from the Buss and Durkee Hostility Inventory. Depression and belief in control by powerful others correlated only for subjects with low scores on Assaultive, Verbal, and Indirect Hostility. The findings, using nonwhite subjects, replicate a previous study in which the racial composition was not indicated.

Alcoholism prevention among Native-American youth

Although Native-Americans represent a diverse population, alcoholism prevention programs need to apply general knowledge of alcohol use and misuse, rather than search for extraordinary cultural factors. Such an approach would emphasize the importance of social relationships, peer group associations, family interactions, and individual adjustment in the prevention of alcoholism among Native-Americans.

Myths about aggression and attitudes about the death penalty

165 college students completed a survey containing a measure of misconceptions about human aggression and attitudinal items on the death penalty from a 1985 Gallup report. Analysis did not provide strong support for the hypothesis that subjects with relatively high numbers of misconceptions about human aggression are more likely than better informed subjects to support the death penalty.

Hostility and guilt among Native American students

Buss and Durkee's Hostility-Guilt Inventory was given to 23 white and 23 Native American college students. The Native American subjects scored significantly higher on the Resentment Hostility subscale while the white students scored higher on the Indirect Hostility and Guilt subscales. Implications for research are discussed.

Locus of control and perceptions of human aggression

116 college students were given a locus of control scale and a measure of misconceptions about human aggression. A negative correlation of -.52 indicated that as feelings of mastery and control increased, belief in a human propensity for aggression decreased.

Mortality rates and aggression management among Native Americans

Using data from the general USA population, Field reported that various causes of death correlated with measures of aggression management obtained from suicide and homicide rates. Since in this study replication of these findings cross-culturally was not successful with data for US Indian Health Service areas and Field did not explain his ecological correlations, the reliability and validity of his findings may be questioned.

Venereal diseases and aggression management among Native Americans

An analysis of secondary data yielded no significant ecological correlations for venereal disease rates and aggression management indices based on suicide and homicide rates for the 11 US Indian Health Services areas. This outcome does not cross-culturally replicate research on Field's aggression management hypothesis.

Accidental and unspecified deaths among prisoners as disguised suicides

Analysis of 1987 data from the US Department of Justice for prisoners under the jurisdiction of state and federal correctional authorities indicated that suicide rates were not negatively correlated with accidental or unspecified death rates. These findings do not provide evidence of disguised suicides among prisoners. Possible explanations for high rates of unspecified death among prisoners are presented.

Native Americans and the constant death instinct hypothesis

To test Tabachnick and Klugman's hypothesis that the amount of death instinct per capita in different regions is constant, 1975-1977 death rates for motor vehicle accidents, cirrhosis, and suicide were obtained from the US Indian Health Service for all 11 health service areas. In contrast to predictions derived from the hypothesis that the death instinct is constant, no negative correlations were found among these three variables. Although an analysis of other behaviors might yield different findings, these results do not support an hypothesis of a constant death instinct among Indian Health Service regions.

Suicide and homicide among Native Americans: anomie or social learning?

Analysis of data for 12 areas of the Indian Health Services from the US Department of Health and Human Services yielded a rho of .61 between poverty and suicide for men and a significant rho of .65 for poverty with homicide rates. The Navajo area is an exception, raising for study questions about social disintegration. For the women, poverty was not significantly related to suicide or homicide rates, raising additional questions about social disintegration.

Regional differences in sodomy laws

As of 1989, 24 states prohibited either heterosexual or homosexual sodomy. This raises for study the following question: in what ways do states with sodomy laws differ from states without sodomy laws. It was hypothesized that states with sodomy laws are more punitive (as measured by the rate of adults under correctional supervision and the number of restricted civil rights for a felony conviction), rural, and southern. Although the first two hypotheses were rejected, states with sodomy laws scored significantly higher than states without such laws on Gastil's Index of Southerness. Sodomy laws may be more commonly found in the South given regional differences in social values about sex, morality, and family life.

Poverty, suicide, and homicide among Native Americans

Analysis of data for 12 areas of the Indian Health Services available from the US Department of Health and Human Services yielded a correlation (rho) of .65 between poverty and suicide and a significant rho of. 52 with homicide rates. The Navajo area is an exception, raising for study questions about social disintegration.

Sensation seeking and self-reported criminality among student-athletes

The present study was conducted to assess whether student-athletes self-report more criminal activities than other students and whether there is a relation between sensation seeking and criminal behavior. In comparison to the control sample of 38, 34 student-athletes scored significantly higher on Zuckerman's Sensation Seeking Scale, Form V, and on a modified version of Canter's Self-report Deviance Checklist. Sensation seeking was not related to self-reported criminality among the control group, but among student-athletes moderately high correlations were found. These findings might suggest another dimension of the theory of sensation seeking among athletes.

Alienation and self-reported deviance

The present study assessed the relationship between alienation and criminal deviance by administering Dean's Alienation Scale and a modified version of Canter's Self-reported Deviance Checklist to 113 undergraduate students of whom 40 were men. The over-all correlation was slight but further analysis showed sex differences. Alienation was moderately related to criminal deviance among men, but not among women.