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At least 307 records · Page 17Linked to original sources
PubMed2001

Neutrophil oscillations: temporal and spatiotemporal aspects of cell behavior.

Neutrophil activation is an essential event in inflammatory responses. How cells coordinate, integrate, manage, and distribute information on physiologically-relevant timescales are not well understood. Although neutrophil oscillators have been known for many years, their biological roles have not been identified. We suggest that intracellular oscillators (such as NAD(P)H, pH, calcium, and so on) account for functional oscillations (e.g., superoxide and NO production, cytolytic marker release, pericellular proteolysis, and actin assembly). In addition to these well-known temporal oscillations, we have recently discovered self-organized traveling chemical waves in neutrophils; these waves respond to extracellular signals and have distinct origins that coincide with a cell's uropod, lamellipodium, or adherence site. The fundamental physico-chemical features of cell chemistry will have an increasing role in our understanding of leukocyte function.

Biological Clocks↗
PubMed1998

Measures and interpretations of vigilance performance: evidence against the detection criterion.

Operators' performance in a vigilance task is often assumed to depend on their choice of a detection criterion. When the signal rate is low this criterion is set high, causing the hit and false alarm rates to be low. With increasing time on task the criterion presumably tends to increase even further, thereby further decreasing the hit and false alarm rates. Virtually all of the empirical evidence for this simple interpretation is based on estimates of the bias measure beta from signal detection theory. In this article, I describe a new approach to studying decision making that does not require the technical assumptions of signal detection theory. The results of this new analysis suggest that the detection criterion is never biased toward either response, even when the signal rate is low and the time on task is long. Two modifications of the signal detection theory framework are considered to account for this seemingly paradoxical result. The first assumes that the signal rate affects the relative sizes of the variances of the information distributions; the second assumes that the signal rate affects the logic of the operator's stopping rule. Actual or potential applications of this research include the improved training and performance assessment of operators in areas such as product quality control, air traffic control, and medical and clinical diagnosis.

Adult↗
PubMed1999

Good vibrations: tactile feedback in support of attention allocation and human-automation coordination in event-driven domains.

Observed breakdowns in human-machine communication can be explained, in part, by the nature of current automation feedback, which relies heavily on focal visual attention. Such feedback is not well suited for capturing attention in case of unexpected changes and events or for supporting the parallel processing of large amounts of data in complex domains. As suggested by multiple-resource theory, one possible solution to this problem is to distribute information across various sensory modalities. A simulator study was conducted to compare the effectiveness of visual, tactile, and redundant visual and tactile cues for indicating unexpected changes in the status of an automated cockpit system. Both tactile conditions resulted in higher detection rates for, and faster response times to, uncommanded mode transitions. Tactile feedback did not interfere with, nor was its effectiveness affected by, the performance of concurrent visual tasks. The observed improvement in task-sharing performance indicates that the introduction of tactile feedback is a promising avenue toward better supporting human-machine communication in event-driven, information-rich domains.

Adult↗
PubMed2006

A resilient, low-frequency, small-world human brain functional network with highly connected association cortical hubs.

Small-world properties have been demonstrated for many complex networks. Here, we applied the discrete wavelet transform to functional magnetic resonance imaging (fMRI) time series, acquired from healthy volunteers in the resting state, to estimate frequency-dependent correlation matrices characterizing functional connectivity between 90 cortical and subcortical regions. After thresholding the wavelet correlation matrices to create undirected graphs of brain functional networks, we found a small-world topology of sparse connections most salient in the low-frequency interval 0.03-0.06 Hz. Global mean path length (2.49) was approximately equivalent to a comparable random network, whereas clustering (0.53) was two times greater; similar parameters have been reported for the network of anatomical connections in the macaque cortex. The human functional network was dominated by a neocortical core of highly connected hubs and had an exponentially truncated power law degree distribution. Hubs included recently evolved regions of the heteromodal association cortex, with long-distance connections to other regions, and more cliquishly connected regions of the unimodal association and primary cortices; paralimbic and limbic regions were topologically more peripheral. The network was more resilient to targeted attack on its hubs than a comparable scale-free network, but about equally resilient to random error. We conclude that correlated, low-frequency oscillations in human fMRI data have a small-world architecture that probably reflects underlying anatomical connectivity of the cortex. Because the major hubs of this network are critical for cognition, its slow dynamics could provide a physiological substrate for segregated and distributed information processing.

Adult↗
PubMed2005

Overview of contemporary reperfusion strategies in acute ST-elevation myocardial infarction.

The rupture of an atherosclerotic plaque in an epicardial coronary artery with subsequent occlusive coronary thrombosis has been established as the decisive event in the pathogenesis of an acute coronary syndrome, which encompasses the clinical entities of unstable angina, non-ST- and ST-elevation myocardial infarction. This article focuses on contemporary treatment strategies for patients with acute ST-elevation myocardial infarction and reviews the role of pharmacologic thrombolysis and mechanical reperfusion by percutaneous transluminal approaches. Statements of the latest guidelines for the treatment of ST-elevation myocardial infarction are included, as well as some recently distributed information not covered by the guideline publications. Finally, some future perspectives for the treatment of acute ST-elevation myocardial infarction are outlined.

Angioplasty, Balloon, Coronary↗
PubMed1997

[Case report of two work accidents investigated using the causal tree method]

In a large company in São Paulo State, two work accidents were investigated using the Causal Tree Method (CTM), leading to the accurate identification of factors related to work organization as the causal factors for the accidents. These cases pointed to the role of organizational factors, such as improvised and temporary assignments to work stations and/or jobs, decisions about the performance of tasks left to unprepared workers, unavailability of proper tools and/or materials, and faulty information distribution within the company. Analysis of the accidents allowed for the presentation and discussion of the method (CTM), its lengthy application, its demands in terms of training, and its potentialities for accident prevention.

Journal Article↗
PubMed2002

[The Internet and self treatment: how to put them together?].

Information and communication technology through the Internet has brought about elements/processes/objects produced in order to be used by humane bio-sciences related to bio-medicine activities, such as public health. ICT has been covering larger domains of medical information, producing fields of specialization known as telemedicine, cyber-medicine and consumers' health information. It tries to meet consumers' need of information, by apparently creating something similar to self-treatment with some expertise. This way, consumers would be able to make more 'educated' decisions in terms of their acquisitions in the area of health. In order to reach this objective, computer programs have come up with health decision aids software. It is clear the mingling of three powers that participate in the mechanisms that organize present day life - instrumental reasoning and its technical production, the power created by the union of institutions and ideologies, and the belief in the myths, symbols and rites of scientific technology. As a possible result, we may have the colonization of societies by authorities that produce specialized knowledge, by professionals that apply such knowledge to produce technological items or pack them in technological cases, by industrial systems and by information, distribution and commercial nets.

History, 20th Century↗
PubMedDate not supplied

Straining, attachment, and detachment of cryptosporidium oocysts in saturated porous media.

Accurate knowledge of the transport and deposition behavior for pathogenic Cryptosporidium parvum oocysts is needed to assess contamination and protect water resources. Experimental and modeling studies were undertaken to examine the roles of attachment, detachment, and straining on oocyst transport and retention. Saturated column studies were conducted using Ottawa aquifer sands (U.S. Silica, Ottawa, IL) with median grain sizes of 710, 360, and 150 microm. Decreasing the median sand size tended to produce lower effluent concentrations, greater oocyst retention in the sand near the column inlet, and breakthrough of oocysts at later times. Oocyst transport data also exhibited concentration tailing. Mathematical modeling of the oocyst transport data using fitted first-order attachment and detachment coefficients provided a satisfactory description of the observed effluent concentration curves, but a poor characterization of the oocyst spatial distribution. Modeling of these data using an irreversible straining term that is depth dependent provided a better description of the oocyst spatial distribution, but could not account for the observed effluent concentration tailing or late breakthrough times. A more physically realistic description of the data was obtained by modeling attachment, detachment, and straining. The percentage of total oocysts retained by straining was estimated from effluent mass balance considerations to be 68% for 710-microm sand, 79% for 360-microm sand, and 87% for 150-microm sand. Straining coefficients were then selected to achieve these percentages of total oocyst retention, and attachment and detachment coefficients were fitted to the effluent concentration curves. Dramatic differences in the predicted oocyst breakthrough curves were observed at greater transport distances for the various model formulations (inclusion or exclusion of straining). Justification for oocyst straining was provided by trends in the transport data, simulation results, pore size distribution information, and published literature.

Animals↗
PubMed1986

Drug promotion: the Third World revisited.

In 1973 and 1980 surveys, much of the promotion of prescription drugs in the Third World was found to be marked by gross exaggeration of clinical claims and glossing over of possible serious or fatal adverse reactions. In an expanded survey of the information distributed in 1984 to physicians in the United States, the United Kingdom, and 28 developing nations in Africa, Asia, and Latin America, striking changes were noted. Many of the pharmaceutical firms were found to be showing more restraint in limiting their claims in the Third World to those which can be supported by scientific evidence, and far more willingness to disclose serious hazards. The companies discarding a double standard in drug promotion have apparently not suffered any significant loss of profits. There is, however, evident need for further improvement by both multinational and domestic companies. The present study covered 1069 products representing 63 drug entities and fixed combinations, marketed by 303 companies.

Africa↗
PubMed2004

Pharmacist computer skills and needs assessment survey.

BACKGROUND: To use technology effectively for the advancement of patient care, pharmacists must possess a variety of computer skills. We recently introduced a novel applied informatics program in this Canadian hospital clinical service unit to enhance the informatics skills of our members. OBJECTIVE: This study was conducted to gain a better understanding of the baseline computer skills and needs of our hospital pharmacists immediately prior to the implementation of an applied informatics program. METHODS: In May 2001, an 84-question written survey was distributed by mail to 106 practicing hospital pharmacists in our multi-site, 1500-bed, acute-adult-tertiary care Canadian teaching hospital in Vancouver, British Columbia. RESULTS: Fifty-eight surveys (55% of total) were returned within the two-week study period. The survey responses reflected the opinions of licensed BSc and PharmD hospital pharmacists with a broad range of pharmacy practice experience. Most respondents had home access to personal computers, and regularly used computers in the work environment for drug distribution, information management, and communication purposes. Few respondents reported experience with handheld computers. Software use experience varied according to application. Although patient-care information software and e-mail were commonly used, experience with spreadsheet, statistical, and presentation software was negligible. The respondents were familiar with Internet search engines, and these were reported to be the most common method of seeking clinical information online. Although many respondents rated themselves as being generally computer literate and not particularly anxious about using computers, the majority believed they required more training to reach their desired level of computer literacy. Lack of familiarity with computer-related terms was prevalent. Self-reported basic computer skill was typically at a moderate level, and varied depending on the task. Specifically, respondents rated their ability to manipulate files, use software help features, and install software as low, but rated their ability to access and navigate the Internet as high. Respondents were generally aware of what online resources were available to them and Clinical Pharmacology was the most commonly employed reference. In terms of anticipated needs, most pharmacists believed they needed to upgrade their computer skills. Medical database and Internet searching skills were identified as those in greatest need of improvement. CONCLUSIONS: Most pharmacists believed they needed to upgrade their computer skills. Medical database and Internet searching skills were identified as those in greatest need of improvement for the purposes of improving practice effectiveness.

Adult↗
PubMed2005

The Internet and clinical trials: background, online resources, examples and issues.

Both the Internet and clinical trials were significant developments in the latter half of the twentieth century: the Internet revolutionized global communications and the randomized controlled trial provided a means to conduct an unbiased comparison of two or more treatments. Large multicenter trials are often burdened with an extensive development time and considerable expense, as well as significant challenges in obtaining, backing up and analyzing large amounts of data. Alongside the increasing complexities of the modern clinical trial has grown the power of the Internet to improve communications, centralize and secure data as well as to distribute information. As more and more clinical trials are required to coordinate multiple trial processes in real time, centers are turning to the Internet for the tools to manage the components of a clinical trial, either in whole or in part, to produce lower costs and faster results. This paper reviews the historical development of the Internet and the randomized controlled trial, describes the Internet resources available that can be used in a clinical trial, reviews some examples of online trials and describes the advantages and disadvantages of using the Internet to conduct a clinical trial. We also extract the characteristics of the 5 largest clinical trials conducted using the Internet to date, which together enrolled over 26000 patients.

Computer Security↗
PubMed2001

A preliminary study of subjective frequency estimates of words spoken in Cantonese.

A database is presented of the subjective frequency estimates for a set of 30 Chinese homophones. The estimates are based on analysis of responses from a simple listening task by 120 University students. On the listening task, they are asked to mention the first meaning thought of upon hearing a Chinese homophone by writing down the corresponding Chinese characters. There was correlation of .66 between the frequency of spoken and written words, suggesting distributional information about the lexical representations is generally independent of modality. These subjective frequency counts should be useful in the construction of material sets for research on word recognition using spoken Chinese (Cantonese).

Adult↗
PubMed1999

What are the livestock industries doing, and what do they need from us?

Livestock industries are facing global competition and revolutionary changes. While facing this global competition, the similarities of many animal meat products require that they compete on a cost-of-production basis. Additional issues include the environmental impact of animal agriculture, the role of animal products in human nutrition, food safety and quality, biotechnology, animal welfare, and market access. Progressive producers are becoming more aware of the needs of their customers and are striving to improve product quality. Checkoff funds are used to finance promotion, research, and consumer information programs and are increasingly used to finance producer education. Industrialization trends in the livestock industries are changing the needs of constituencies, delivery mechanisms, and relationships with the people involved. Characteristics of closed operations include high production cost, outdated technology, smaller size, older operators, and lack of management focus. Successful operations tend to be growing in capacity, are system-oriented, maintain high throughput, keep accurate records, use outside consultants, and control production costs. Modern livestock production has lowered the cost of production by integrating new production and management technologies. In order for producers to be successful in the future, access to technology, capital, and timely information will be critical. Animal scientists have many common objectives with livestock industries. Their work in research, teaching, and extension is critical for continued progress. However, people in the industries sometimes have the perception that academic arrogance, discipline myopia, uncoordinated research, slow technology transfer, increasing research costs, and counter-productive tenure systems prevent animal scientists from being as relevant and responsive as they could be. Support from the industries is essential as animal scientists and academic departments seek political and funding support. This support can be attained by including integrated systems research, improving communication skills, achieving more efficient research budgets, rapidly publishing results, reducing the cost of information distribution, developing flexible research agendas, retraining scientists, acquiring modern methods, and emphasizing critical thinking, communication, and teamwork when teaching.

Animal Husbandry↗
PubMed1987

A quantitative comparison of stimulus-response relationships of vibrissa-activated neurons in subnuclei oralis and interpolaris of the rat's trigeminal sensory complex: receptive field properties and threshold distributions.

Electrical activity of single vibrissa-activated neurons was recorded in pars interpolaris and pars oralis of the nucleus of the trigeminal spinal tract of rats. Stimuli consisted of quantitatively controlled deflections of individual mystacial vibrissae. The evoked spike trains were analyzed as point-process time series with a variety of quantitative procedures. Most second-order trigeminal neurons were directionally sensitive. About one-third of interpolaris neurons and over half of oralis neurons responded to axial push of the hair shaft. About half of the neurons of both oralis and interpolaris had receptive fields that included more than one vibrissa. The upper-quartile receptive field size of neurons of interpolaris was about half that of oralis, although the distributions overlapped. In interpolaris, almost one-fifth of the sample discharged in the absence of an intentionally applied stimulus; in oralis, over one-third of the sample displayed background activity. The ranges of angular displacement thresholds of both samples exceeded three orders of magnitude. The distributions differed quantitatively. They were, nevertheless, similar in shape, and exhibited considerable overlap. The median threshold of oralis neurons was about half that of interpolaris neurons, and about one-fifth that of first-order neurons. About one-fourth of the second-order neurons exhibited a nonmonotonic relationship between pulse displacement and the number of evoked spikes. Neurons of interpolaris tended to be more severely nonmonotonic than those of oralis, and some "turned off" at stimulus magnitudes well above threshold. Nevertheless, the number of spikes evoked in either entire sample was a monotonically increasing function of pulse displacement. The range of angular velocity thresholds observed in both second-order samples exceeded three orders of magnitude. As with the angular displacement thresholds, the distributions of angular velocity thresholds were quantitatively different, although their shapes and extremes were similar, and they overlapped extensively. The observed differences of stimulus-response relationships of the neurons in interpolaris and oralis reflect differences in the ways different trigeminal nuclei receive, process, and distribute information to the circuits in which they participate.

Animals↗
PubMed2006

Major advances in genetic evaluation techniques.

The past quarter-century in genetic evaluation of dairy cattle has been marked by evolution in methodology and computer capacity, expansion in the array of evaluated traits, and globalization. Animal models replaced sire and sire-maternal grandsire models and, more recently, application of Bayesian theory has become standard. Individual test-day observations have been used more effectively in estimation of lactation yield or directly as input to evaluation models. Computer speed and storage are less limiting in choosing procedures. The increased capabilities have supported evaluation of additional traits that affect the net profitability of dairy cows. The importance of traits other than yield has increased, in a few cases due to an antagonistic relationship with yield. National evaluations combined internationally provide evaluations for bulls from all participating countries on each of the national scales, facilitating choices from among many more bulls. Selection within countries has increased inbreeding and the use of similar genetics across countries reduces the previously available outcross population. Concern about inbreeding has prompted changes in evaluation methodology and mating practices, and has promoted interest in crossbreeding. In just the past decade, distribution of genetic evaluations has gone from mailed paper or computer tapes for a limited audience to publicly accessible, request-driven distribution via the Internet. Among the distributed information is a choice of economic indices that combine an increasing array of traits into numbers reflecting breeding goals under different milk-pricing conditions. Considerable progress in genomics and the mapping of the bovine genome have identified markers for some deleterious recessive genes, but broader benefits of marker-assisted selection are still in the future. A possible exception is the proprietary use of DNA testing by semen producers to select among potential progeny test bulls. The collection and analysis of industry-wide data to evaluate genetic merit will continue to be the most important tool for genetic progress into the foreseeable future.

Animals↗
PubMed1998

Restricted maximum likelihood analysis of linkage between genetic markers and quantitative trait loci for a granddaughter design.

A REML for the estimation of location and variance of a single quantitative trait locus, together with polygenic and residual variance, is described for the analysis of a granddaughter design. The method is based on a mixed linear model that includes the allelic effects of the quantitative trait locus, which are assumed to be normally distributed. Information from four marker loci situated on a single chromosome was available to derive the covariances at the linked quantitative trait locus. A derivative-free algorithm is described that makes use of the specific structure of the granddaughter design. The procedure has been applied to simulated data for a granddaughter design with 50 grandsire families of 40 sires each. Error variance was 60, and total additive genetic variance equaled 40; the quantitative trait locus explained either 10 or 25% of the latter variance. The size of the marker bracket containing the quantitative trait locus was either 10 or 30 cM. The power of detecting the quantitative trait locus ranged from 19 to 99%. Estimates of total genetic variance and variance explained by the quantitative trait locus were found to be empirically unbiased. A small bias was found in location estimates, especially when markers were not fully informative. The accuracy of parameter estimates was greatly improved by the use of information from individual daughters.

Animals↗
PubMed2002

The Eyelink Toolbox: eye tracking with MATLAB and the Psychophysics Toolbox.

The Eyelink Toolbox software supports the measurement of eye movements. The toolbox provides an interface between a high-level interpreted language (MATLAB), a visual display programming toolbox (Psychophysics Toolbox), and a video-based eyetracker (Eyelink). The Eyelink Toolbox enables experimenters to measure eye movements while simultaneously executing the stimulus presentation routines provided by the Psychophysics Toolbox. Example programs are included with the toolbox distribution. Information on the Eyelink Toolbox can be found at http://psychtoolbox.org/.

Eye Movements↗
PubMed2002

Cognitive theories as reinforcement history surrogates: the case of likelihood ratio models of human recognition memory.

B. F. Skinner (1977) once argued that cognitive theories are essentially surrogates for the organism's (usually unknown) reinforcement history. In this article, we argue that this notion applies rather directly to a class of likelihood ratio models of human recognition memory. The point is not that such models are fundamentally flawed or that they are not useful and should be abandoned. Instead, the point is that the role of reinforcement history in shaping memory decisions could help to explain what otherwise must be explained by assuming that subjects are inexplicably endowed with the relevant distributional information and computational abilities. To the degree that a role for an organism's reinforcement history is appreciated, the importance of animal memory research in understanding human memory comes into clearer focus. As Skinner was also fond of pointing out, it is only in the animal laboratory that an organism's history of reinforcement can be precisely controlled and its effects on behavior clearly understood.

Animals↗