New statistical methods for investigating submarine pockmarks

We investigate the applicability of some novel spatial analysis techniques, developed for studies of astrophysical datasets, to the analysis of spatial point data in sedimentary basins. The techniques are evaluated and compared with standard methods using two test areas that contain large numbers of submarine pockmarks developed in distributed arrays. The familiar Ripley K and Voronoi tesselation techniques are used, and the results are then compared with those obtained using more novel techniques, the correlation length and minimal spanning tree. The correlation length technique is found to identify the precise distances at which clustering occurs more accurately, making a physical interpretation more clear than is possible using the Ripley K. The minimal spanning tree is found to be powerful at identifying the space-filling nature of the pockmark distribution, and has the advantage of being immune to edge effects. The use of these two novel techniques permits more information to be extracted from the datasets, and demonstrates clear statistically significant differences between them, which are not detectable using standard techniques.     

Long‐Term Structural Evolution of an Intercalated Layered Semiconductor

Intercalated molecules can dramatically modify the electronic band structure of layered semiconductors, significantly altering the optical properties of the material. In the layered monochalcogenide Gallium Telluride (GaTe), exposure to air induces a nearly 1 eV reduction of its band gap due to the interlayer diffusion and chemisorption of oxygen. The effect of oxygen chemisorption at the Te‐terminated surfaces on the structure of GaTe, however, is much less known. To better understand the structure–property relationship of intercalated GaTe, a systematic, long‐term, X‐ray diffraction study has been performed on GaTe exfoliated crystals exposed to ambient conditions. It is observed that the structural changes are not limited to a previously observed short‐term increase in lattice expansion. Over the course of months and even years after exfoliation, the oxygen adsorbates continue to modify the structure of GaTe, inducing significant disorder and grain reorientation. It is estimated that approximately one out of every two grains is slightly displaced by the intercalating oxygen, demonstrating a significant increase in grain mosaicity, while still maintaining the original {?2 0 1} out‐of‐plane texture. Correlating these structural transformations to observed changes in electrical and optical properties will enable capitalization of the use of adsorbates to engineer novel properties in these layered materials.     

Sequential detection of three-dimensional signals under dependent noise

We study detection methods for multivariable signals under dependent noise. The main focus is on three-dimensional signals; that is, on signals in the space–time domain. Examples for such signals are multifaceted. They include geographic and climatic data as well as image data that are observed over a fixed time horizon. We assume that the signal is observed as a finite block of noisy samples whereby we are interested in detecting changes from a given reference signal. Our detector statistic is based on a sequential partial sum process, related to classical signal decomposition and reconstruction approaches applied to the sampled signal. We show that this detector process converges weakly under the no change null hypothesis that the signal coincides with the reference signal, provided that the spatial–temporal partial sum process associated with the random field of the noise terms disturbing the sampled signal converges to a Brownian motion. More generally, we also establish the limiting distribution under a wide class of local alternatives that allows for smooth as well as discontinuous changes. Our results also cover extensions to the case in which the reference signal is unknown. We conclude with an extensive simulation study of the detection algorithm.     

Polymer-based fabrication techniques for enclosed microchannels in biomedical applications

Investigations and analyses of body fluids like serum or whole blood are essential tasks in biomedical research in order to understand and diagnose diseases, to conduct pharmacological tests or to culture cells. Therefore, microfluidic systems provide a favorable tool for processing fluid samples as they allow downscaling of sample volumes and handling of single fluid components such as cells or proteins. For this reason, we present simple fabrication techniques for microchannel systems using polymer materials only. The demonstrated fabrication procedures are based on combinations of acrylic glass and the photo resists SU-8 and PerMX3020. On the one hand, these materials are low-priced compared to conventional silicon or glass. On the other hand, they have not shown any interaction with blood or other cell suspensions within the frame of our study. Furthermore, their transparency guarantees an easy observability of all processes within the system. Depending on the channel dimensions, different adhesion bonding techniques for closing of the systems are applied, whereas the fluidic interfaces are included by mechanical drilling. Summing up, we provide complete fabrication processes for fluidic systems which are simpler and more cost-effective than conventional methods and yet cope with all essential requirements for microfluidic applications.     

Primes and targets in rapid chases: Tracing sequential waves of motor activation.

Single-cell recordings have indicated that visual stimuli elicit rapid waves of neuronal activation that propagate so fast that they might be free of intracortical feedback. Here, the time course of feedforward activation was traced by measuring pointing responses to color targets preceded by color primes initiating either the same or opposite response. The early time course of priming effects was strictly time locked to prime onset and depended only on properties of the primes, but was independent of the onset times of the actual targets as well as the perceptual effects of targets on primes. Results indicated that nonoverlapping feedforward signals by primes and targets traverse the visuomotor system in a rapid chase, controlling associated motor responses in strict sequence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of early abuse on adult affective reactions to exposure to dyadic conflict.

Studied the relationship between abuse in the family of origin and adult emotional responses to family conflicts in 60 males (mean age 19.7 yrs) and 60 females (mean age 19.6 yrs). Ss were administered the Conflict Tactics Scale and the Adjective Checklist (AC) to assess the tactics used by them to solve their problems and their emotional state, respectively. Ss listened to conflict tapes and completed another AC along with a set of perceptual questions. Exposure to conflict tactics in the family of origin was associated with heightened emotional responses to anticipated conflict, the effects being continued into adulthood. Antecedents to conflict were also related to family of origin experience with withdrawal, verbal and physical abuse. There was no significant difference between identification with the mother and the child, and the Ss identified more strongly with the father than the child. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavior of mother rats in conflict tests sensitive to antianxiety agents.

The purpose of this investigation was to observe the behavior of mother rats in conflict tests. In the punished drinking test, in which licking from a water spout is punished by electric shocks, mothers (observed on Day 1 postpartum following 24 hr of water deprivation) were found to drink more than virgins. Mothers (Day 1 postpartum) also consumed more food than controls in an unfamiliar open field. In contrast, no difference between mothers (Day 5 postpartum) and virgins was present in the exploration of an electrified shock probe. The largest maternal anticonflict effects in the drinking and feeding tests were recorded when the females were tested with their pups. Increased punished drinking was also observed in virgin rats treated with the anxiolytic benzodiazepine midazolam. Following 24 hr of water deprivation, unpunished drinking was higher in lactating females than in virgins, so the increased acceptance of punishment by mothers might have been due to their being more thirsty than virgins. However, virgins, deprived of water for 48 hr and whose unpunished drinking was similar to that of mothers deprived for 24 hr, did not accept as many punishments as the lactating females. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The experience of homeless women: An exploration of housing histories and the meaning of home

The exploratory study with homeless women presented in this paper aims to highlight two shortcomings in the current literature on homelessness, which accompany the predominant conceptualisation of ‘home’ as a place of safety and security, and homelessness as a primarily structural issue characterised by ‘residential instability’. The first is the paucity of research on homeless women in their own right and the second the lack of studies which examine underlying reasons for residential instability from homeless women's own perspectives. An intensive, small sample interview study was carried out with 12 regular women users of a day centre for homeless people (Brighton, south of England). They were asked about their patterns of residence, reasons for moving, definitions of ‘house’, ‘home’, and ‘ideal home’, and they gave their housing histories in some detail. In a quantitative analysis, their patterns of moving and definitions of ‘home’ were compared to those of a group of securely housed women. Number of moves was comparable in both groups, but for the homeless women the majority of moves had been made to avoid abuse and social services relocations. Whilst all of the securely housed women could confidently define a difference in meaning between a ‘house’ and a ‘home’, only 3 of the 12 homeless women did. They equated ‘home’ with safety and security, the same terms used in the literature to define what housing means, and the two most salient features largely absent in homeless women's experience of housing. The meaning of home is further explored in a qualitative analysis, where the themes of safety and security—or rather their absence in abusive relationships—are traced through the homeless women's childhood, adolescence and adulthood. These exploratory findings question an easy equation between ‘residential instability’ and homelessness, and highlight the need to investigate further the reasons why women leave housing, and the relationship this has to an understanding of what ‘home’ means. Whilst current formulations suggest that the homelessness of women is a problem, and housing the solution, this study suggests that housing is the problem—homelessness may well be a solution.