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At least 1,783 records · Page 99Linked to original sources
PubMed2001

Multiple dipole analysis of visual event-related potentials during oddball paradigm with silent counting.

In order to cope with the non-uniqueness of multiple equivalent current dipole source (ECD) solutions, a priori knowledge about P300 generators of visual event-related potentials (ERPs) during an oddball paradigm with silent counting task was incorporated into the multiple ECD localization method. Four-ECD solutions for the target P300 were selected which had the left frontal ECD. The rest of the ECDs were localized to the inferior parietal lobule, the hippocampal formation and subcortical region. By comparing the present results with those on the visual ERPs with button-pressing task, the P300 dipoles common to both the tasks were located at the frontal cortices, the hippocampal formation and the thalamus, suggesting that these structures are the main P300 generators.

Adult↗
PubMedDate not supplied

Spatiotemporal analysis of environmental exposure-health effect associations.

The goal of this work is to discuss a general methodology for studying associations between environmental exposures and health effect by means of the spatiotemporal random field theory. This theory is the tool of choice for rigorously accounting for important spatiotemporal variations and uncertainties related to exposures and effect. Within the framework of the random field theory, the Bayesian maximum entropy model neatly synthesizes various sources of physical and epidemiological knowledge into spatiotemporal analysis. Therefore, unlike technical statistics, this approach relies on the blending of substantive physical knowledge with powerful mathematical techniques and a coherent rationale. Given the well-founded fact that certain health effects may be caused by environmental exposures, the significance of these exposures is assessed in terms of a criterion that is based on the joint stochastic representation of exposure and health-effect distributions in space/time. In view of this criterion, the strength and consistency of the exposure-effect association are evaluated on the basis of the health-effect predictions that the combined physico-epidemiologic analysis generates in space/time. The main features of the approach are demonstrated by a simulation example and a real case study involving mortality and cold temperatures in North Carolina. The studies demonstrated the practical usefulness of the stochastic human exposure analysis in assessing the exposure-effect association. The results reported here emphasize the links between spatiotemporal models of physical systems and population health-effect distributions, thus suggesting directions for improving the current understanding of quantitative "exposure-health effect" functions.

Cold Temperature↗
PubMed2003

Can an in silico drug-target search method be used to probe potential mechanisms of medicinal plant ingredients?

Medicinal plants have been explored therapeutically in traditional medicines and are a valuable source for drug discovery. Insufficient knowledge about the molecular mechanism of these medicinal plants limits the scope of their application and hinders the effort to design new drugs using the therapeutic principles of herbal medicines. This problem can be partially alleviated if efficient methods for rapid identification of protein targets of herbal ingredients can be introduced. Efforts have been directed at developing efficient computer methods for facilitating target identification. Various methods being explored or under investigation are reviewed here. So far, one computer method, INVDOCK, has been specifically used for automated drug target identification. Its usefulness in the identification of therapeutic targets of medicinal herbal ingredients as well as synthetic chemicals is reviewed. The majority of INVDOCK identified therapeutic targets of several well-known medicinal herbal ingredients have been found to be confirmed or implicated by experiments, which suggests the potential of in silico methods in facilitating the study of molecular mechanism of medicinal plants.

Algorithms↗
PubMed1998

Triangulation in nursing research: issues of conceptual clarity and purpose.

The controversy concerning the value of qualitative, quantitative and triangulation approaches to nursing research for understanding human behaviour and increasing nursing knowledge has been an increasing source of debate among nurse scholars. However, the differences and similarities of these three perspectives have not been fully compared as either philosophies or methodologies. The purposes of this paper are to provide an understanding of the origin and development of the triangulation research method, clarify major sources of confusion in the presentation of a triangulation study, and discuss the problems and possible solutions of a triangulation study. Finally, an example of multiple triangulation in a nursing research within a Taiwanese cultural context -- turning points of recovery from cardiac surgery during the intensive care unit transition -- is presented. In the course of the paper, suggestions are also given to help nurse researchers recognize when it is most appropriate to use a certain research method, whether that be qualitative, quantitative or triangulation.

Cardiovascular Surgical Procedures↗
PubMed2002

Current concepts: organophosphate toxicity.

Recent cases of nosocomial poisoning associated with the treatment of patients contaminated with organophosphate (OP) insecticides and the increasing potential for exposure to these chemicals elevate into sharper focus the continuing clinical and public health problem of pesticide poisoning. Despite a number of reports on the multiple aspects of OPs insecticides and their health effects, the general public and health services professionals, broadly defined, remain confused and misinformed about this class of chemicals. In this article we examine sources of exposure and current knowledge of health effects of OPs. The protection of health care workers is also discussed.

Humans↗
PubMed1996

Barriers to follow-up of abnormal screening mammograms among low-income minority women. Cancer Control Center of Harlem.

OBJECTIVE: To describe factors related to compliance diagnostic follow-up among minority women of low socioeconomic status with abnormal screening mammograms. METHODS: A retrospective cross-sectional survey using a structured telephone interview. Three cancer screening clinics at an urban inner-city public hospital. All women with abnormal screening mammograms between September 1990 and January 1992 were eligible; women were interviewed in August 1992. Abnormal mammograms were those requiring specific, non-routine clinical follow-up; non-compliance was defined as delayed follow-up (four to six months after the date of the mammogram), or no follow-up at the time of interview (more than 6 months after abnormal). RESULTS: Sixty-two of 442 screened women had abnormal results; the overall rate of non-compliance with follow-up was 50%. Among the 42 (68%) women who agreed to be interviewed, non-compliers were less likely to state that they had been told to receive follow-up than compliers (65% versus 100%; p = 0.008). Non-compliant women were less likely to have suspicious mammography interpretations (p = 0.05), and more likely to report barriers to follow-up, such as cost of lost wages and medical care, system barriers, or fears, than compliant women (61.9% versus 9%, p = 0.01). There were no differences between the two groups for age, education, insurance, source of care, family history, knowledge or attitudes. CONCLUSIONS: These preliminary results suggest that follow-up of low income, minority women with abnormal screening mammograms could be enhanced by improved communication of results. Future studies should extend these findings with larger samples and in other settings and populations.

Adolescent↗
PubMed1987

Double peak attenuation method for estimating organ location.

Radioactive sources of finite volume containing 133Xe, 67Ga, 99Tcm and 111In were used to measure the attenuation coefficient, mu, in water at six different energies in the range 80-296 keV using an Anger camera. The experimental accuracy was about 7% for the volume range from 40-225 ml when corrections were made for background. The same radioactive sources were used to measure zero attenuation count rates per unit of activity. The theoretical basis was also derived, which confirms our experimental findings, i.e. the measurement of the thickness of the attenuator using a dual energy method. The determination of the linear attenuation coefficient in the broad-beam geometry situation is possible by accounting for cross-talk, scatter and out-of-target activity. By correcting for the broad-beam geometry, agreement with the narrow-beam geometry linear attenuation coefficient was obtained. We also demonstrate the use of the technique to accurately determine the depth of the organ using two separate energies. This methodology is independent of the organ volume for determination of the depth. It is hoped that our findings will provide a better understanding of the photon interactions when extended sources are used. Such a knowledge can also be applied to organ volume measurements.

Humans↗
PubMed2003

Internet addiction of adolescents in Taiwan: an interview study.

This study presented a follow-up investigation of a series of studies about Taiwanese adolescents' Internet addiction. Through analyzing a series of questionnaires, 10 Taiwanese adolescents with Internet addiction were selected for in-depth interviews. Adolescents' interview data revealed the following: First, almost all of the interviewed adolescents exhibited most of the symptoms of Internet addiction as identified by previous studies, including compulsive use and withdrawal, tolerance, and related problems of school, health, family, finance, and time management. Moreover, almost all of the interviewed adolescents stated that messages on the Internet became the primary source of their information and knowledge. Many of them were addicted to the messages and activity on the Internet, but not by the Internet as a medium per se. Also, the world of the Internet seemed to become a place to relieve adolescents' depression. Most of the interviewed adolescents self-declared that they were Internet addicts, but none of them could clearly state what to do with such an addiction. Psychologists and educators should pay more attention to this and then propose possible solutions for adolescents.

Adolescent↗
PubMed1999

DNA sequencing with positive and negative errors.

The problem addressed in this paper is concerned with DNA sequencing by hybridization. An algorithm is proposed that solves a computational phase of this approach in the presence of both positive and negative errors resulting from the hybridization experiment. No a priori knowledge of the nature and source of these errors is required. An extensive set of computational experiments showed that the algorithm behaves surprisingly well if only positive errors appear. The general case, where positive and negative errors occur, can be also solved satisfactorily for an error rate up to 10%.

Algorithms↗
PubMed2001

Starch digestion rate in the small intestine of broiler chickens differs among feedstuffs.

Dietary starch is the major energy source for broiler chickens, and knowledge about its digestive behavior can be important. In a digestibility trial with 720 broiler chickens, site, rate and extent of starch digestion were measured for 12 feedstuffs. Starch digestion was determined using the slaughter technique, which involves removal of the small intestine from the recently killed chicken, with manual collection of the contents. Starch digestion coefficients were calculated from remaining starch in three segments of the small intestine and in excreta. Mean retention time in four segments of the small intestine was measured. This enabled calculations for starch digestion rate (k(d)). Ileal starch digestibility varied from 33% (potato starch) to 99% (tapioca). Retention time for digesta in the postduodenal small intestine varied from 136 min (barley diet) to 182 min (potato diet). On the basis of starch digestion rates, a distinction was made between slowly digestible starch (k(d) < 1 h(-1)), gradually digestible starch (k(d):1-2 h(-1)) and rapidly digestible starch (k(d) > 2 h(-1)). Starch from common beans was digested most slowly (k(d): 0.5 h(-1)), and starch from tapioca was digested most rapidly (k(d): 4.3 h(-1)). Starch digestion rates of potato starch and legume seeds were lower than those of cereal grains and tapioca. Degradation of starch entering the hind gut of the birds did not occur. Milling of corn affected rate, but not the extent of starch digestion. We concluded that site of starch digestion within the small intestine is not an accurate indicator for starch digestion rate.

Absorption↗
PubMed2002

Cancer screening practices from National Health Interview Surveys: past, present, and future.

The National Health Interview Survey (NHIS) has provided data about health behaviors at the national level since 1957. The 1987 and 1992 Cancer Control Supplements to the NHIS, along with other supplemental surveys administered intermittently on self-reported cancer-related behaviors, have contributed to important research and public health purposes. In this article, we reviewed 73 papers published between 1980 and 2001 that used NHIS data, including the first report from the 1998 NHIS, to examine what has been learned from past surveys. Our goal was to facilitate future analyses of recently released data on cancer screening practices from the Cancer Control Supplement to the 2000 NHIS, which is now known as the Cancer Control Module. We categorized the papers according to which of the following three study approaches they used: trends in screening rates, correlates of these rates with factors that may influence screening, and linkages or comparisons of NHIS data with other surveys or sources of information. We summarize knowledge gained in cancer screening for each of these three categories and identify areas that could benefit from more research. We highlight some of the new information available for the first time on the Cancer Control Module of the 2000 NHIS as fresh opportunities for cancer control research. Finally, we describe how the Cancer Control Supplements to the NHIS are integrated with the objectives of and developments in national cancer surveillance research that have emerged from federal planning efforts and collaborations with national partners in cancer surveillance in recent years.

Attitude to Health↗
PubMed2007

Quantification of plant stress using remote sensing observations and crop models: the case of nitrogen management.

Remote sensing techniques offer a unique solution for mapping stress and monitoring its time-course. This article reviews the main issues to be addressed for quantifying stress level from remote sensing observations, and to mitigate its impact on crop production by managing cultural practices. The case of nitrogen fertilization is used here as a paradigm. The derivation of canopy state variables such as the leaf area index (LAI) and chlorophyll content (C(ab)) is first addressed. It is demonstrated that the inversion of radiative transfer models leads to useful estimates of these variables. However, because of the ill-posed nature of the inverse problem, better accuracy is achieved when using prior information on the distribution of the variables and when multiplying LAI by C(ab) to get canopy level chlorophyll content. This variable, LAIxC(ab) is well suited for quantifying canopy level nitrogen content. It is used for nitrogen stress evaluation by comparison with a reference unstressed situation which is, however, not easy to get in practice. The combination of remote sensing observations with crop models provides an elegant solution for stress quantification through assimilation approaches. It fuses several sources of information within our knowledge of the processes involved and accounts for the environmental budget which can be integrated when making decisions about cultural practices. Conclusions are drawn on the issues related to the retrieval of canopy state variables from remote sensing data, to the link between these observables and crop models, and to the assimilation approaches. Avenues for further research are finally discussed along with the required observation system.

Biosensing Techniques↗
PubMed1979

Adult bacteremia caused by gram-negative bacilli.

Because gram-negative bacteremia is increasing in frequency, it is important for physicians to suspect, carefully evaluate, and initiate early appropriate therapy. Identification of the probable source of bacteremia and a knowledge of the hospital microflora are helpful in guiding antibiotic selection. The mortality of gram-negative bacteremia tends to vary with the severity of the underlying disease and, accordingly, tends to be low in obstetrical patients. Prevention is the most effective method of controlling these infections and, therefore, care and discretion when employing invasive devices is essential. With the increasing incidence of these infections and the increased threat of antibiotic plasmid resistance, future infection control in high-risk patients by immunoprophylaxis may be necessary.

Anti-Bacterial Agents↗
PubMedDate not supplied

Creation and analysis of a computerized database of interventions to facilitate adult sleep.

BACKGROUND: Although sleep problems are a frequent complaint of ill and older adults, there is no ready source of continually updated scientific knowledge about sleep promotion interventions used by nurses. OBJECTIVES: To create a database of sleep promotion research and to describe the nature and strength of studies about nursing interventions used to promote sleep in adults. METHODS: Computer, hand, ancestry, and author searches were used to identify nursing and related-discipline studies of sleep promotion in adults. An experimental software program, arcs, was used to store, retrieve, examine, and summarize sleep research findings. RESULTS: Twelve interventions within the basic scope of nursing practice were identified. All were nonpharmacologic. Interventions were grouped according to their presumed mechanism of action: 1) to relax the sleeper, 2) to manage noise, 3) to re-pattern the sleep-wake schedule, or 4) to inform the sleeper about sleep hygiene. CONCLUSIONS: The research base underpinning sleep promotion practices in nursing is sparse. The use of relaxation approaches to promote sleep in those with chronic insomnia has the most support. Extensive research involving other interventions and populations is needed. As more studies become available, they can be added to the computer database, thus facilitating dissemination of scientific knowledge to guide nursing practice.

Adult↗
PubMed2001

Surfing for back pain patients: the nature and quality of back pain information on the Internet.

STUDY DESIGN: A prospective, systematic review of web sites related to back pain. OBJECTIVE: To assess the nature and quality of back pain-related information on the World Wide Web during a 2-year period. SUMMARY OF BACKGROUND DATA: The Internet has become a rich source of medical information. Limited knowledge is available, however, about the quality of online resources. Although previous systematic reviews on medical-related web sites found problems in varying degrees with the credibility of information, no such review was conducted to assess the back pain-related sites. METHODS: A search of web sites was conducted in November 1996 using five search engines (AltaVista, Infoseek, Lycos, Yahoo, and Magellan) and two key terms ("back pain" and "back problems"). A sample of sites was evaluated by two independent reviewers. Each site was described by the type and nature of the sponsor, target audience, and content. Overall quality was assessed in terms of evidence-based information available. RESULTS: Seventy-four web sites were reviewed in 1996, and nine of them (12.2%) were identified as high-quality sites. Advertising was the focus of 80.8% of the sites. Eleven sites (14.9%) were found to be discontinued 1 year later, and 20 (27.0%) were not accessible by the reviewers at the 2-year follow-up evaluation. Of the remaining 54 sites, 44.4% were produced by for-profit companies, and most sites targeted people with back pain (63.0%). Only seven out of the nine high-quality sites held their ratings at the 2-year follow-up evaluation. CONCLUSION: Most back pain-related web sites can be classified as advertising. The quality varied considerably, resulting in difficulties for patients to find useful information in this field. The increasing number of people seeking medical information on the Web creates a need for more high quality sites. Further, systematic review of web sites should be encouraged to monitor the accuracy of Internet publication.

Bias↗
PubMed2005

Local observation and spectroscopy of optical modes in an active photonic-crystal microcavity.

We report the direct, room-temperature, near-field mapping and spectroscopy of the optical modes of a photonic-crystal microcavity containing quantum wells. We use a near-field optical probe to reveal the imprint of the cavity mode structure on the quantum-well emission. Furthermore, near-field spectroscopy allows us to demonstrate the strong spatial and spectral dependence of the coupling between the sources and the microcavity. This knowledge will be essential in devising future nanophotonic devices.

Journal Article↗
PubMed2006

The role of mast cells in atopy: what can we learn from canine models? A thorough review of the biology of mast cells in canine and human systems.

Mast cell research has largely focused on the role of these cells in the early phase of allergic reactions. However, their involvement may well extend beyond this stage, and even reach across nonallergic conditions. Mast cells from different sources have helped advance our knowledge of their biology. Although in vitro and in vivo research in this area has mainly focused on humans, such studies are limited by the extent to which cells from certain human tissues and/or human patients can be collected or studied. While rodents also provide valuable models with which to further our understanding of the behaviour of mast cells and their contribution to allergy, reported differences between human and murine mast cells, and, in some instances, the limitations of in vivo rodent models of mast cell-mediated allergic conditions, preclude their use. In this review, we introduce a relatively unknown mast cell population, that of the dog. Canine mast cells display many phenotypic and functional similarities with their human counterparts, and dogs develop spontaneous and induced allergic diseases that share clinical and pathophysiological features with the human condition. Therefore, the use of canine cells can shed light on the general role of mast cells, particularly in relation to allergic diseases given the potential of in vivo dog models within this field. Here we provide a detailed review of the data reported from in vitro and in vivo studies of canine mast cells, and compare them with results obtained in human systems. We also highlight direct evidence of the mast cell contribution to canine atopy. We conclude that the dog offers useful in vitro and in vivo models in which to investigate mast cell behaviour, and that its use should be considered when undertaking studies aimed either at elucidating the role of mast cells in health and disease, or at prescreening novel therapies prior to entry into man.

Animals↗
PubMed1992

Relationship between oral gram-negative anaerobic bacteria in saliva of the mother and the colonization of her edentulous infant.

Various gram-negative anaerobic bacterial species can be detected in the oral flora of edentulous infants. However, knowledge of the initial infection source is still scarce. Thirty Caucasian mothers (mean age 30 years) and their edentulous infants (mean age 3 months) were examined for the possible similarity of the oral gram-negative anaerobic flora. Paraffin-stimulated saliva was collected from the mothers. A pooled swab sample from mucosal surfaces and unstimulated saliva were collected from the infants. The samples were inoculated on nonselective and selective media and cultured aerobically and anaerobically. All of the 30 mothers harbored Fusobacterium nucleatum and 29 mothers Prevotella melaninogenica in their saliva. The salivary levels of P. melaninogenica, F. nucleatum, nonpigmented Prevotella spp., Prevotella intermedia and Prevotella loescheii exceeded 10(4) CFU/ml in about half of the 30 mothers. At this maternal salivary level, the infants' colonization frequency of P. melaninogenica and F. nucleatum was doubled. A positive correlation between maternal salivary concentration and infant's colonization was found for P. melaninogenica. No positive association was found with nonpigmented Prevotella spp., P. intermedia and P. loescheii. It can be speculated that maternal saliva may act as a source of some gram-negative anaerobes in the oral microflora of edentulous infants as early as before tooth eruption.

Adult↗