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PubMed1998

Over the hill and far away: distance as a barrier to the provision of assistance to elderly relatives.

This paper considers the impact of the distance between employed caregivers and their elderly relatives on the provision of various forms of family-based assistance ("eldercare"), and in so doing it contributes to two overlapping literatures, one on the geography of care for elderly persons and the other on eldercare as a "work and family" issue. The paper also seeks to interpret and understand the spatiality of eldercare in light of evolving public policy on the care of dependent populations, and does so with an eye to the highly gendered nature of family caregiving. The empirical portion of the paper draws on a national survey of work and family conducted by CARNET (The Canadian Aging Research Network). Analysis of data for 1149 respondents with eldercare responsibilities reveals significant distance-decay effects in the average (weekly) number of hours devoted to eldercare. However, disaggregation by gender reveals that only male caregivers display this normative behaviour. Analysis of the average time-distances at which particular types of assistance are provided reveals a similar "gender gap"--women are willing to travel farther, more often, than male caregivers. The results suggest that the reconceptualization of aging as a "private" problem, to be attended to (by women) in the family and community, will particularly affect the careers and family lives of female caregivers, for they are more likely than their male counterparts to take on more travel and try to squeeze more into already tight time budgets.

Activities of Daily Living↗
PubMed2004

Why do breast cancer patients decline entry into randomised trials and how do they feel about their decision later: a prospective, longitudinal, in-depth interview study.

This paper presents an exploration of the reasons why breast cancer patients decline entry into randomised clinical trials of adjuvant cancer therapy. The study employed a qualitative, longitudinal design based on in-depth interview post diagnosis, with follow-up interviews at 6 and 12 months later. Twenty-two consecutive patients, newly diagnosed with breast cancer, who had declined entry into a clinical trial were prospectively recruited from five outpatient breast cancer clinics in the North Trent Cancer Network. Analysis of patients' narratives indicated that fear of the illness and limited understanding of medical research in general, compounded by unhelpful explanations of the trial purpose and process by health professionals, resulted in patients opting for the 'tried and tested' treatment. Some patients had persisting guilt about their decision not to take part. Many of the reasons why breast cancer patients decline entry to clinical trials could be addressed, as they tend to be a product of situational and process factors, rather than being rooted in deep-seated antipathy towards research.

Adult↗
PubMed1998

Vision-guided navigation using SHOSLIF.

This paper presents an unconventional approach to vision-guided autonomous navigation. The system recalls information about scenes and navigational experience using content-based retrieval from a visual database. To achieve a high applicability to various road types, we do not impose a priori scene features, such as road edges, that the system must use, but rather, the system automatically derives features from images during supervised learning. To accomplish this, the system uses principle component analysis and linear discriminant analysis to automatically derive the most expressive features (MEF) for scene reconstruction or the most discriminating features (MDF) for scene classification. These features best describe or classify the population of the scenes and approximate complex decision regions using piecewise linear boundaries up to a desired accuracy. A new self-organizing scheme called recursive partition tree (RPT) is used for automatic construction of a vision-and-control database, which quickly prunes the data set in the content-based search and results in a low time complexity of O(log(n)) for retrieval from a database of size n. The system combines principle component and linear discriminant analysis networks with a decision tree network. It has been tested on a mobile robot, Rome, in an unknown indoor environment to learn scenes and the associated navigation experience. In the performing phase, the mobile robot navigates autonomously in similar environments, while allowing the presence of scene perturbations such as the presence of passersby.

Journal Article↗
PubMed2001

Routes of drug administration, differential affiliation, and lifestyle stability among cocaine and opiate users: implications to HIV prevention.

Types of drugs used and routes of administration were assessed, and correlations to social affiliation, HIV status, and lifestyle stability were explored among 672 street-recruited drug users in Baltimore. Participants reported 63 patterns of drug use, which were categorized into five groups: (1) only sniff heroin; (2) smoke crack and may snort cocaine; (3) sniff heroin and smoke crack; (4) inject heroin and cocaine; and (5) inject heroin and cocaine, smoke crack, and may snort heroin. Social network analysis revealed that heroin sniffers and crack smokers both tended to associate with those with similar drug use patterns. High symptoms of drug dependence were observed among heroin users irrespective of mode of administration. Injectors reported higher rates of hospitalization compared to noninjectors even after adjusting for HIV status. Implications to HIV prevention and drug use transitions are discussed.

Adult↗
PubMed1999

Frontotemporal interactions in face encoding and recognition.

Cognition may result from different patterns of neural interactions distributed across the brain. If this is true then across different cognitive tasks different functional interactions should be observed within an anatomical network. To investigate this hypothesis, a network analysis of PET data obtained from a face memory study was conducted. PET scans were obtained while subjects performed face perception, face encoding and face recognition tasks. Partial least squares (PLS) analysis of rCBF was used to identify brain regions that were engaged during these tasks, and anatomically based structural equation modeling (SEM) was used to construct functional models for matching, encoding and recognition. There was some overlap in the functional interactions observed across the three cognitive tasks. In all three tasks, there were positive interactions involving the left occipitotemporal regions. These interactions may represent the perceptual component of the three tasks. Task-specific functional interactions were also observed. During face encoding, there was a bilateral positive influence of occipitotemporal regions on medial temporal regions. In addition, there were positive interhemispheric interactions between middle temporal regions and between limbic regions during encoding. These patterns may reflect the participation of medial temporal cortex in the formation of new memories. In the face recognition task, there was a positive loop in the right hemisphere from occipital cortex to frontal cortex and back from frontal cortex to occipitotemporal cortex. In addition, there was a strong positive input into the right hippocampal region from right occipitotemporal cortex. This pattern of interaction was specific to the recognition task and might represent the process whereby the input faces are compared to the internal representation laid down during encoding, thus enabling recognition.

Adult↗
PubMed2003

Sexual networks: implications for the transmission of sexually transmitted infections.

The structures of sexual networks are essential for understanding the dynamics of sexually transmitted infections. Standard epidemiological models largely disregard the complex patterns of intimate contacts. Social network analysis offers important insight into how to conceptualize and model social interaction and has the potential to greatly enhance the understanding of disease epidemics.

Contact Tracing↗
PubMed2000

Adsorptions of plasma proteins and their elutabilities from a polysiloxane surface studied by an on-line acoustic wave sensor.

Gold electrodes of thickness-shear mode acoustic wave sensors were modified with poly[(mercaptopropyl)methylsiloxane]. The flow-through adsorption of three major plasma proteins (human serum albumin, fibrinogen, and immunoglobulin G) was detected by acoustic network analysis. The elution of fibrinogen and albumin from coated and unmodified gold surfaces by sodium dodecyl sulfate was studied with respect to different adsorption times and protein concentrations. Both sequential and competitive adsorptions of the three proteins on polymer-modified surfaces of sensors were examined as were simultaneous adsorptions from binary and ternary mixtures. The experimental results confirm that the competitive behaviors of proteins in terms of adsorptive processes are explained by factors other than displacement phenomena.

Acoustics↗
PubMedDate not supplied

Inhibition of the tyrosine kinase, Syk, analyzed by stepwise nonparametric regression.

A set of 538 inhibitors of the tyrosine kinase, Syk, including purines, pyrimidines, indoles, imidazoles, pyrazoles, and quinazolines, has been analyzed using a stepwise nonparametric regression (SNPR) algorithm, which has been developed for QSAR studies of pharmacological data. The algorithm couples stepwise descriptor selection with flexible, nonparametric, kernel regression, to generate structure-activity relationships. A further 371 molecules have been used as a test set to evaluate the models generated. Descriptors were selected using an internal monitoring set, and models were assessed using 10% of the principal (538-compound) data set, selected randomly, as an external validation set. The best model had a Q(2) of 0.46 for the external validation set. Test set predictions were significantly less accurate, partly due to the higher mean activity of the test molecules. However at a more coarse-grain level the SNPR models classified active molecules accurately, giving good enrichments. The data sets are difficult to model accurately and SNPR performs better than multilinear regression and a neural network analysis. In the additive implementation of SNPR multidimensional models are considered as a sum of single dimensional regressions. This makes the resultant models easily interpretable. For example, in the most predictive SNPR models, there is a clear nonlinear relationship between hydrophobicity (AlogP98) and inhibitory activity.

Enzyme Inhibitors↗
PubMed2005

Tris(dithiolene) complexes of neodymium and cerium: mononuclear species, chains, and honeycomb networks.

Reactions of Ln(BH4)3(THF)3 (Ln = Nd, Ce) and M2dddt (M = Na, K; dddt = 5,6-dihydro-1,4-dithiine-2,3-dithiolate) in THF or pyridine gave, after addition of 18c6 (18-crown-6), several crystalline compounds which all contain the tris(dithiolene) Ln(dddt)3 unit. Crystals of [Na(18c6)(py)2]2[Na(18c6)(py)][Nd(dddt)3(py)].3py (1.3py) are built up from discrete mononuclear cationic and anionic species whereas crystals of {[Na(18c6)(py)2](0.5)[Na(18c6)(py)(1.5)][Na(1.5)Nd(dddt)3]}(infinity) (2) are composed of discrete [Na(18c6)(py)x]+ cations and polymeric anionic two-dimensional layers in which the Nd(dddt)3 units are linked to three neighbors by sodium atoms to form a honeycomb network. Analysis of the temperature dependence of the molar magnetic susceptibility of 2 shows that chiMT decreases from 1.63 cm3 K mol(-1) at 300 K down to 0.6 cm3 K mol(-1) at 5 K, due to the crystal-field splitting of the (4)I(9/2) free-ion state. Complexes {[Na3(18c6)(1.5)Nd(dddt)3(THF)].3THF}(infinity) (3.3THF) and {[K3(18c6)(1.5)Nd(dddt)3(py)].3py}(infinity) (4.3py) exhibit neutral polymeric layers with the Nd(dddt)3 units linked by M2(18c6) fragments. In the cerium compound {[Na2(18c6)Na(py)2Ce(dddt)3(py)].3py}(infinity) (5.3py), each Ce(dddt)3 unit is linked to two neighbors only by Na2(18c6) moieties, giving infinite zigzag chains.

Journal Article↗
PubMed2006

Bulk acoustic resonator based on piezoelectric ZnO belts.

In this paper, a bulk acoustic resonator based on ZnO belts is demonstrated. This device shows a great deal of promise in applications as an electronic filter and as a mass sensor. The fabricated device was characterized using vector network analysis, and both the first and third harmonics of resonance were observed at approximately 247 and 754 MHz, respectively. A one-dimensional Krimholt-Leedom-Matthaei model was utilized to predict the resonant frequency of the device and confirm the observed behavior.

Acoustics↗
PubMed2002

Panic disorder in African-Americans: symptomatology and isolated sleep paralysis.

While attention has been paid to the study of panic disorder (PD) with or without agoraphobia among Caucasians, surprisingly little empirical research within the United States has looked at the phenomenology of PD among minority groups. In this paper we present data we have collected and review other research on the phenomenology, social supports, and coping behavior among African-Americans with panic disorder. Our studies indicate that, in comparison to Caucasians, African-Americans with PD reported more intense fears of dying or going crazy, as well as higher levels of numbing and tingling in their extremities. African-Americans reported higher rates of comorbid post traumatic disorder and more depression. African-Americans also used somewhat different coping strategies (such as religiosity and counting one's blessings), less self-blame, and were somewhat more dissatisfied with social supports. The incidence of isolated sleep paralysis was, as per previous reports, higher in African-Americans. These findings, results of other research, and the implications for assessment and treatment are discussed within a semantic network analysis of panic (Hinton and Hinton 2002, this issue).

Adaptation, Psychological↗
PubMed1999

Team leadership: network differences in women's and men's instrumental and expressive relations.

Recent studies have emphasised differences in leadership styles between women and men. Women have an "interactive" leadership style while men are more "directive" and "authoritative." Social network analysis is used to examine differences in eight mental health case management teams, half formally supervised by women and half by men. The techniques used are graphical displays and measures of centrality. Results show male leaders as the most central team member for both instrumental and expressive relations. Female leaders, however, do not adhere to a single leadership style. Team centralisation also differs with gender composition of teams influencing leadership differences.

Adult↗
PubMed2003

Reconceptualizing quantitative and qualitative methods: a case study dealing with place as an exemplar.

A useful framework for understanding methods is to think of them as being on a continuum of holistic and pattern focused to particularistic and specific. This paper argues for this conceptualization rather than thinking of quantitative and qualitative methods as oppositional and potentially contradictory. A case study provides an example of using both quantitative and qualitative methods in a holistic and pattern-focused study, while also attending to the values and goals of community psychology. The substantive research goal is to understand a child's experience of places related to school. Methods include ethnographic long-term participation and observation, interviews, multidimensional scaling, and social network analysis. Most quantitative method variables are generated from study participants; no outside structure is imposed. The quantitative methods extend and inform the qualitative methods, just as the qualitative methods extend and inform the quantitative methods. The quantitative and qualitative methods work reciprocally to extend and inform each other.

Black or African American↗
PubMed1999

Second by second patterns in cortical electroencephalograph and systolic blood pressure during Cheyne-Stokes.

Little is known about how arousal develops during the ventilatory phase of Cheyne-Stokes breathing. This study employs neural network analysis of electroencephalograms (EEGs) to describe these changes and relate them to changes in systolic blood pressure, which is probably a subcortical marker of arousal. Six patients with Cheyne-Stokes respiration (apnoea/hypopnoea index 32-69 h(-1)) caused by stable chronic heart failure underwent polysomnography including arterial beat-to-beat systolic blood pressure determination. Periods of 15 sequential apnoeas during nonrapid eye movement sleep were identified for each subject. For each apnoea, the EEG was examined second-by-second using neural net analysis from 28 s before to 28 s after apnoea termination (first return of oronasal airflow), and this was compared with the systolic blood pressure pattern. During the apnoeic phase, sleep deepened progressively. Arousal started to develop at or just before apnoea termination and progresses through the breathing phase. The rise and fall in the systolic blood pressure closely followed the rise and fall in electroencephalographic sleep depth. In conclusion, during Cheyne-Stokes breathing, cortical electroencephalographic arousal begins at or just before the resumption of breathing. Cortical electroencephalographic sleep depth changes are closely mirrored by changes in arterial systolic blood pressure, suggesting that the state changes in the cortical and basal brain structures may be synchronous.

Arousal↗
PubMed1999

Friendship clique and peer influences on body image concerns, dietary restraint, extreme weight-loss behaviors, and binge eating in adolescent girls.

This study explored friendship variables in relation to body image, dietary restraint, extreme weight-loss behaviors (EWEBs), and binge eating in adolescent girls. From 523 girls, 79 friendship cliques were identified using social network analysis. Participants completed questionnaires that assessed body image concerns, eating, friendship relations, and psychological family, and media variables. Similarity was greater for within than for between friendship cliques for body image concerns, dietary restraint, and EWLBs, but not for binge eating. Cliques high in body image concerns and dieting manifested these concerns in ways consistent with a high weight/shape-preoccupied subculture. Friendship attitudes contributed significantly to the prediction of individual body image concern and eating behaviors. Use of EWLBs by friends predicted an individual's own level of use.

Adolescent↗
PubMed1991

The perceived causal structure of loneliness.

Two studies examined the way people represent the causes of loneliness as a semantic space and as a causal network. In a multidimensional scaling task, the results of Michela, Peplau, and Weeks (1982) were replicated and the causes wee classified according to locus and stability. In a 2nd study, 44 people judged the likelihood that these causes were interconnected. From these data, a causal network or perceived causal structure (Kelley, 1983) was derived by means of network analysis. The structure revealed a complex lay theory of loneliness in which personality influenced group behavior, which in turn influenced psychological states and beliefs. States and beliefs were also affected by physical features and situational factors.

Adult↗
PubMed1987

Perception of three-dimensional form from patterns of optical texture.

The research described in the present article was designed to investigate how patterns of optical texture provide information about the three-dimensional structure of objects in space. Four experiments were performed in which observers were asked to judge the perceived depth of simulated ellipsoid surfaces under a variety of experimental conditions. The results revealed that judged depth increases linearly with simulated depth although the slope of this relation varies significantly among different types of texture patterns. Random variations in the sizes and shapes of individual surface elements have no detectable effect on observers' judgments. The perception of three-dimensional form is quite strong for surfaces displayed under parallel projection, but the amount of apparent depth is slightly less than for identical surfaces displayed under polar projection. Finally, the perceived depth of a surface is eliminated if the optical elements in a display are not sufficiently elongated or if they are not approximately aligned with one another. A theoretical explanation of these findings is proposed based on the neural network analysis of Grossberg and Mingolla.

Attention↗
PubMed2006

Robust Salmonella metabolism limits possibilities for new antimicrobials.

New antibiotics are urgently needed to control infectious diseases. Metabolic enzymes could represent attractive targets for such antibiotics, but in vivo target validation is largely lacking. Here we have obtained in vivo information about over 700 Salmonella enterica enzymes from network analysis of mutant phenotypes, genome comparisons and Salmonella proteomes from infected mice. Over 400 of these enzymes are non-essential for Salmonella virulence, reflecting extensive metabolic redundancies and access to surprisingly diverse host nutrients. The essential enzymes identified were almost exclusively associated with a small subgroup of pathways, enabling us to perform a nearly exhaustive screen. Sixty-four enzymes identified as essential in Salmonella are conserved in other important human pathogens, but almost all belong to metabolic pathways that are inhibited by current antibiotics or that have previously been considered for antimicrobial development. Our comprehensive in vivo analysis thus suggests a shortage of new metabolic targets for broad-spectrum antibiotics, and draws attention to some previously known but unexploited targets.

Animals↗