Cluster analysis of radionuclide concentrations in beach sand.

This paper presents a method in which natural radionuclide concentrations of beach sand minerals are traced along a stretch of coast by cluster analysis. This analysis yields two groups of mineral deposit with different origins. The method deviates from standard methods of following dispersal of radionuclides in the environment, which are usually based on the construction of lines of equal concentrations. The paper focuses on the methodology of quantitatively correlating activity concentrations of natural radionuclides in two groups of minerals. The methodology is widely applicable, but is demonstrated for natural radioactivity in beach sands along the coast of South West Australia.

Violence against women during the Liberian civil conflict.

CONTEXT: Civilians were often the casualties of fighting during the recent Liberian civil conflict. Liberian health care workers played a crucial role in documenting violence against women by soldiers and fighters during the war. OBJECTIVE: To document women's experiences of violence, including rape and sexual coercion, from a soldier or fighter during 5 years of the Liberian civil war from 1989 through 1994. DESIGN: Interview and survey. SETTING: High schools, markets, displaced persons camps, and urban communities in Monrovia, Liberia, in 1994. PARTICIPANTS: A random sample of 205 women and girls between the ages of 15 and 70 years (88% participation rate). RESULTS: One hundred (49%) of 205 participants reported experiencing at least 1 act of physical or sexual violence by a soldier or fighter. Survey participants reported being beaten, tied up, or detained in a room under armed guard (17%); strip-searched 1 or more times (32%); and raped, subjected to attempted rape, or sexually coerced (15%). Women who were accused of belonging to a particular ethnic group or fighting faction or who were forced to cook for a soldier or fighter were at increased risk for physical and sexual violence. Of the 106 women and girls accused of belonging to an ethnic group or faction, 65 (61%) reported that they were beaten, locked up, strip-searched, or subjected to attempted rape, compared with 27 (27%) of the 99 women who were not accused (P< or =.02, .07, .001, and .06, respectively). Women and girls who were forced to cook for a soldier or fighter were more likely to report experiencing rape, attempted rape, or sexual coercion than those who were not forced to cook (55% vs 10%; P< or =.001, .06, and .001, respectively). Young women (those younger than 25 years) were more likely than women 25 years or older to report experiencing attempted rape and sexual coercion (18% vs 4%, P=.02 and .04, respectively). CONCLUSIONS: This collaborative research allowed Liberian women to document wartime violence against women in their own communities and to develop a unique program to address violence against women in Liberia.

Estrogen and sequential movement.

Normal movement depends in part on the brain's ability to produce and use dopamine, which regulates basal ganglia function. Behavioral, neuroanatomical, and neurophysiological data suggest that the basal ganglia are critical for the performance of sequential movement. Dopaminergic function is modulated by estrogen in animals and in humans. To test the hypothesis that estrogen modulates sequential movement, this study measured the reaction time (RT) and movement time (MT) of 15 women and 10 men in a choice RT task with sequential responses. Higher levels of estradiol in women's blood were associated with faster total movement time (RT plus MT). Testosterone levels in women's blood were not associated with keypressing performance. Hormone levels in men's blood were unrelated to keypressing performance. These results suggest that women's motor performance was affected by hormone levels, and that estrogen may interact with dopaminergic function in women.

Time series analysis in the time domain and resampling methods for studies of functional magnetic resonance brain imaging.

Although functional magnetic resonance imaging (fMRI) methods yield rich temporal and spatial data for even a single subject, universally accepted data analysis techniques have not been developed that use all the potential information from fMRI of the brain. Specifically, temporal correlations and confounds are a problem in assessing change within pixels. Spatial correlations across pixels are a problem in determining regions of activation and in correcting for multiple significance tests. We propose methods that address these issues in the analysis of task-related changes in mean signal intensity for individual subjects. Our approach to temporally based problems within pixels is to employ a model based on autoregressive-moving average (ARMA or "Box-Jenkins") time series methods, which we call CARMA (Contrasts and ARMA). To adjust for performing multiple significance tests across pixels, taking into account between-pixel correlations, we propose adjustment of P values with "resampling methods." Our objective is to produce two- or three-dimensional brain maps that provide, at each pixel in the map, an estimated P value with absolute meaning. That is, each P value approximates the probability of having obtained by chance the observed signal effect at that pixel, given that the null hypothesis is true. Simulated and real data examples are provided.

The hippocampal formation participates in novel picture encoding: evidence from functional magnetic resonance imaging.

Considerable evidence exists to support the hypothesis that the hippocampus and related medial temporal lobe structures are crucial for the encoding and storage of information in long-term memory. Few human imaging studies, however, have successfully shown signal intensity changes in these areas during encoding or retrieval. Using functional magnetic resonance imaging (fMRI), we studied normal human subjects while they performed a novel picture encoding task. High-speed echo-planar imaging techniques evaluated fMRI signal changes throughout the brain. During the encoding of novel pictures, statistically significant increases in fMRI signal were observed bilaterally in the posterior hippocampal formation and parahippocampal gyrus and in the lingual and fusiform gyri. To our knowledge, this experiment is the first fMRI study to show robust signal changes in the human hippocampal region. It also provides evidence that the encoding of novel, complex pictures depends upon an interaction between ventral cortical regions, specialized for object vision, and the hippocampal formation and parahippocampal gyrus, specialized for long-term memory.

Evidence of Incomplete Motor Programming in Parkinson's Disease.

One of the essential questions regarding movement deficits in Parkinson's disease (PD) is whether they stem from impaired selecting and switching among movements, impaired use of predictive information to prepare movement, or impaired execution of movement. PD subjects (n equals 9) and age-matched control subjects (n equals 8) performed a cued, sequential-response RT task. The cue provided either no information, accurate information, or inaccurate information about the upcoming response. PD subjects used predictive information to prepare and to switch among movement sequences normally, but second and third key press latencies were prolonged in comparison with the first key press latency. In Experiments 2 and 3, the effects of choice set and sequence length on key press latencies were examined. These results provide evidence that PD subjects initiate movement before the entire response sequence is prepared. PD does not impair motor programming or execution processes themselves but impairs the smooth coordination of those processes.

Computergraphic modeling and analysis II: three-dimensional reconstruction and interactive analysis.

The analysis of human motion can be advanced by analyzing motion not only numerically, but also graphically. A new system is presented for the computergraphic analysis of human motion in three-dimensional space. The system allows the three-dimensional reconstruction, visualization, manipulation, and graphic editing of digitized movement trajectories. An entire sequence of the positions of the arm in three-dimensional space can be displayed simultaneously, or the actual motion can be recreated in real time. Along with the reconstruction of the spatial path, the temporal characteristics of the movement can be concurrently displayed. Graphic procedures for interactively examining couplings between spatial and temporal aspects of trajectories were developed. Finally, based on digitized trajectories, stimuli can be generated and sequenced in real time for studies of the perception of motion. In conjunction with new methods of three-dimensional movement tracking, the computergraphic methods presented here offer new approaches to the analysis of human movement and its underlying neural control.

Unusual presacral tumours obstructing delivery.

Two patients who had obstructed labour due to a presacral tumour are reported. Both tumours were diagnosed in the second stage of labour. In one patient delivery was accomplished with Barton's forceps. The other patient required a Caesarean section. The tumours were excised at later date. One was an epidermoid cyst and the other was thought to be a malignant haemangioendothelioma.