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PubMed1984

Selective attention and the organization of visual information.

Theories of visual attention deal with the limit on our ability to see (and later report) several things at once. These theories fall into three broad classes. Object-based theories propose a limit on the number of separate objects that can be perceived simultaneously. Discrimination-based theories propose a limit on the number of separate discriminations that can be made. Space-based theories propose a limit on the spatial area from which information can be taken up. To distinguish these views, the present experiments used small (less than 1 degree), brief, foveal displays, each consisting of two overlapping objects (a box with a line struck through it). It was found that two judgments that concern the same object can be made simultaneously without loss of accuracy, whereas two judgments that concern different objects cannot. Neither the similarity nor the difficulty of required discriminations, nor the spatial distribution of information, could account for the results. The experiments support a view in which parallel, preattentive processes serve to segment the field into separate objects, followed by a process of focal attention that deals with only one object at a time. This view is also able to account for results taken to support both discrimination-based and space-based theories.

Adolescent↗

PubMed1996

C-fos expression in the brainstem after voluntary ingestion of sucrose in the rat.

Neurons showing activity after sweet taste stimulation, were detected with c-fos immunocytochemistry, to identify brainstem nuclei involved in processing taste information. The distribution of the evoked expression of c-fos was visualized in the rat brainstem after voluntary ingestion of sucrose. Sucrose-taste-specific c-fos immunoreactive neurons were found within the medial part of the nucleus of the solitary tract, the dorsal motor nucleus of the vagus at caudal levels, the paratrigeminal nucleus and the lateral and medial part of the parabrachial nucleus. These nuclei are known to be involved in the processing of information related to ingestive behavior such as information about taste quality. The present study has shown that c-fos is a useful anatomical marker for activated neurons in the rat brainstem, and that the above-mentioned brainstem areas are involved in the processing of sweet taste information.

Animals↗

PubMed1995

Binaural advantage for sound pattern identification.

Listeners were trained to identify six patterns of eight sequentially presented 48-ms tone bursts. The variation in frequency forming the patterns was confined to a relatively narrow range around the nominal center frequency, which was either 500, 1000, or 3000 Hz, or was selected randomly on each presentation from a range of 450-3300 Hz. Detection (500 and 3000 Hz only) and identification of the six patterns masked by Gaussian noise was measured in two interaural presentation conditions: masker in-phase and signal in-phase (NoSo), and masker in-phase and signal pi rad out-of-phase (NoS pi). The differences in performance in the two interaural presentation conditions for detection and identification are referred to as "masking-level differences" (MLDs) and "identification-level differences" (IDLDs), respectively. At 500 Hz, MLDs and IDLDs were about 11-13 dB. At 3000 Hz, the MLDs and IDLDs were about 1-3 dB. For the random-center-frequency condition, the slopes of the identification-level functions were much shallower for the NoS pi condition than for the NoSo condition so the binaural advantage was large at low signal-to-noise ratios and declined as signal-to-noise ratio increased. This finding was due to the broad frequency range over which the information was distributed and the decline in the binaural advantage with increasing frequency, a conclusion consistent with that reported for the binaural advantage for speech intelligibility. A second experiment demonstrated that MLDs and IDLDs could be manipulated independently: A 500-Hz tone was added to each element of the 3000-Hz patterns. A large MLD was found--due to detection of the 500-Hz tone--while the identification-level functions were determined solely by the high-frequency information, which produced small IDLDs. Finally, the Gaussian noise masker was replaced by an informational masker comprised of eight randomly chosen eight-tone bursts played simultaneously with the signal-pattern elements which were centered at 1000 Hz. Large amounts of informational masking were found for identification. The slopes of the identification-level functions were much shallower than found for the Gaussian noise masker and a relatively small binaural advantage (about 5 dB) was observed.

Adult↗

PubMed2005

Prokaryotic phylogenies inferred from protein structural domains.

The determination of the phylogenetic relationships among microorganisms has long relied primarily on gene sequence information. Given that prokaryotic organisms often lack morphological characteristics amenable to phylogenetic analysis, prokaryotic phylogenies, in particular, are often based on sequence data. In this work, we explore a new source of phylogenetic information, the distribution of protein structural domains within fully sequenced prokaryotic genomes. The evolution of the structural domains we use has been studied extensively, allowing us to base our phylogenetic methods on testable theoretical models of structural evolution. We find that the methods that produce reasonable phylogenetic relationships are indeed the methods that are most consistent with theoretical evolutionary models. This work represents, to our knowledge, the first such theoretically motivated phylogeny, as well as the first application of structural information to phylogeny on this scale. Our results have strong implications for the phylogenetic relationships among prokaryotic organisms and for the understanding of protein evolution as a whole.

Archaeal Proteins↗

PubMed2005

Fisher information matrix of the Dirichlet-multinomial distribution.

In this paper we derive explicit expressions for the elements of the exact Fisher information matrix of the Dirichlet-multinomial distribution. We show that exact calculation is based on the beta-binomial probability function rather than that of the Dirichlet-multinomial and this makes the exact calculation quite easy. The exact results are expected to be useful for the calculation of standard errors of the maximum likelihood estimates of the beta-binomial parameters and those of the Dirichlet-multinomial parameters for data that arise in practice in toxicology and other similar fields. Standard errors of the maximum likelihood estimates of the beta-binomial parameters and those of the Dirichlet-multinomial parameters, based on the exact and the asymptotic Fisher information matrix based on the Dirichlet distribution, are obtained for a set of data from Haseman and Soares (1976), a dataset from Mosimann (1962) and a more recent dataset from Chen, Kodell, Howe and Gaylor (1991). There is substantial difference between the standard errors of the estimates based on the exact Fisher information matrix and those based on the asymptotic Fisher information matrix.

Abnormalities, Drug-Induced↗

PubMed1997

Evolution of the Intranet in the University Hospital of Gent.

The explosive development of the internet in recent years has lead to the production of massive collections of web-based tools and development know-how. Implementing an Intranet solution within a health care environment offers tremendous advantages for internal information management, distribution and collaborative computing. Easy adaptability, scalability and the low development cost allow easy integration into existing health care structures. A key aspect of the UZ Gent Intranet is its transparent interaction with the currently implemented HIS thus providing an open gateway to the future.

Belgium↗

PubMed1994

Distribution of bluetongue virus in Turkey, 1978-81.

Information about the distribution of bluetongue in Turkey during 1978-81 has been obtained by serological surveys in cattle, sheep and goats. The group-specific immunodiffusion test was used to identify the presence of bluetongue virus (BTV) in a given province and the type-specific microneutralization test to decide which virus types had been in circulation. By drawing sera from accurately aged donor animals in May and August 1980, it was possible to draw up a general outline of the distribution of BTV in Turkey between early 1978 and mid 1980. By combining the same technique with spring and autumn field visits it became possible to make detailed inferences about the distribution of BTV serotypes in 1980 and 1981. The results support the conclusion that BTV was widespread in central and western Turkey for a number of years and suggests that overwintering can be a regular occurrence in that country. When compared with contemporaneous results from Syria and Jordan, a unifying and well-defined bluetongue virus ecosystem becomes apparent.

Aging↗

PubMed1986

What's in a name? Country-of-origin influences on the earnings of immigrants in the United States.

"In this paper we focus on the migration-related processes that may lead to the well-documented differences in earnings and in naturalization rates across country-of-origin groups in the United States. Our theoretical framework examines how the forces of selectivity associated with the decisions by residents of non-U.S. countries to migrate to the United States and with the decisions by foreign-born U.S. residents to remain in the United States are influenced by country conditions and are reflected ultimately in the observed earnings differences among the 'survivors' of these processes who are enumerated in U.S. sample surveys. In particular, we assess how economic conditions, origin-country attractiveness, costs of migration, the quantity and quality of information, and the country-specific restrictions of U.S. immigration law influence both who migrates to and, among the migrants, who remains in the United States. The framework is applied to two U.S. data sets--a sample of the foreign born in the 1980 Census and a sample from the 1971 cohort of legal immigrants."

Americas↗

PubMed2001

Confidence of compliance: a Bayesian approach for percentile standards.

Rules for assessing compliance with percentile standards commonly limit the number of exceedances permitted in a batch of samples taken over a defined assessment period. Such rules are commonly developed using classical statistical methods. Results from alternative Bayesian methods are presented (using beta-distributed prior information and a binomial likelihood), resulting in "confidence of compliance" graphs. These allow simple reading of the consumer's risk and the supplier's risks for any proposed rule. The influence of the prior assumptions required by the Bayesian technique on the confidence results is demonstrated, using two reference priors (uniform and Jeffreys') and also using optimistic and pessimistic user-defined priors. All four give less pessimistic results than does the classical technique, because interpreting classical results as "confidence of compliance" actually invokes a Bayesian approach with an extreme prior distribution. Jeffreys' prior is shown to be the most generally appropriate choice of prior distribution. Cost savings can be expected using rules based on this approach.

Bayes Theorem↗

PubMed2000

Role of prefrontal cortex in a network for arbitrary visuomotor mapping.

In arbitrary visuomotor mapping, an object instructs a particular action or target of action, but does so in a particular way. In other forms of visuomotor control, the object is either the target of action (termed standard mapping) or its location provides the information needed for targeting (termed transformational mapping). By contrast, in arbitrary mapping, the object's location bears no systematic spatial relationship with the action. Neuropsychological and neurophysiological investigation has, in large part, identified the neural network that underlies the rapid acquisition and performance of arbitrary visuomotor mappings. This network consists of parts of the premotor (PM) and prefrontal (PF) cortex, the hippocampal system (HS), and the basal ganglia (BG). Here, we propose specialized contributions of the network's different components to its overall function. To do so, we invoke the concept of distributed information-processing architectures, or modules, which may involve a variety of neural structures. According to this view, recurrent neural networks involving cortex, basal ganglia, and thalamus operate largely in parallel. Each of these interacting networks can be termed a cortical-BG module. A large number of these modules include PM neurons, and they can be termed PM cortical-BG modules. A comparable number include PF neurons, termed PF cortical-BG modules. We propose that PM and PF cortical-BG modules compute specific object-to-action mappings, in which the network learns the action associated with a given input. These mappings serve as specific solutions to arbitrary visuomotor mapping problems. However, they are also exemplars of more abstract rules, such as the knowledge that nonspatial visual information (e.g., color) can guide the choice of action. We propose that PF cortical-BG modules subserve abstract rules of this kind, along with other problem-solving strategies. This view should not be taken to imply that the PF network lacks the capacity to compute specific mappings, but rather that it has higher-order mapping functions in addition to its lower-order ones. Furthermore, it seems likely that PF provides PM with pertinent sensory information. The hippocampal system appears to play a role parallel to that of both neocortical-BG networks discussed here. However, in accord with several models, it operates mainly in the intermediate term, pending the consolidation of the relevant information in those neocortical-BG networks.

Animals↗

PubMed1998

Solid-state 13C NMR investigations of the glycosidic linkage in alpha-alpha' trehalose.

The sugar trehalose is known to play a central role in the desiccation tolerance of many organisms. Essential to trehalose's role are its glass forming abilities and ability to directly interact with lipid molecules. Detailed information on the structure and dynamics of glassy trehalose and its interactions with lipids, however, have been elusive. We have used solid-state NMR and ab initio quantum mechanical methods (Gaussian 94) in order to characterize the possible molecular conformations of trehalose. Using a simplified structure (2-(tetrahydropyran-2-yloxy) tetrahydropyran) as a model we have calculated the energy and 13C magnetic shielding parameters as a function of the two glycosidic torsion angles. Combining ab initio derived maps and using the 13C lineshape as constraints we were able to construct the torsion angle distribution map for alpha-alpha' trehalose. We believe measurements of 13C isotropic chemical shift and other solid-state NMR tensor parameter distributions in combination with ab initio methods can prove useful in identifying sources of structural disorder in glassy trehalose. By monitoring these structural distributions new information about the membrane surface associative properties of trehalose and other sugars should be accessible.

Carbohydrate Conformation↗

PubMed2001

Private pharmacy practice and regulation. A randomized trial in Lao P.D.R.

OBJECTIVES: The objective of this study was to assess the effectiveness of government regulation of private pharmacy practice in a low-income country. METHODS: The intervention comprised inspections of the pharmacies, information, and distribution of documents to drug sellers and sanctions. It was implemented at two different intensity levels, active and regular intervention. The methods used to assess the effect of the interventions were interviews with the district drug inspectors, drug sellers and customers, inspection of drug purchases, and indicator surveys of pharmacies. Indicators for pharmacy-specific quality as well as for dispensing quality were developed. RESULTS: The main finding was one of strong overall improvements from initially low levels. The improvements were particularly marked by increases in the availability of essential materials for dispensing by 34% and in order in the pharmacy by 19%. Information given to customers increased from 35% to 51% and the mixing of different drugs in the same package went down from 17% to 9%. The pharmacies in the active intervention districts showed greater improvements for four of the six indicators, although statistically significant compared with the regular intervention districts only for the essential materials indicator. CONCLUSIONS: It was concluded that the regulatory activities have probably been an important factor behind the service quality improvements. It appeared feasible as well as effective to regulate private pharmacy practice in this particular low-income setting.

Developing Countries↗

PubMed2006

[Current level of patients' knowledge of anaesthesiology].

The anaesthesiologist's competence in anaesthesia, intensive care medicine, pain therapy and emergency medicine is accepted throughout the medical society. Nevertheless, during the last decades patient surveys demonstrated a considerable lack of information of the responsibility of our work. By continuous education and information anaesthesiologists have aimed to improve the information and decision-making process for the patient. This multicentre trial was designed to investigate the current public view on our profession in seven German hospitals. In-hospital patients were asked to fill out a standardised questionnaire prior to the anaesthesia premedication visit and a total of 692 questionnaires (77%) were analysed. Results demonstrated an increased level of knowledge for anaesthesia (>95%), intensive care medicine (74%), and pain therapy (50% acute pain; 32% severe pain). In the case of emergency medicine (10%) the in-hospital and out-of-hospital responsibilities were not clear among patients. We conclude that the continuous distribution of information in recent years has contributed to improving patients' knowledge on interdisciplinary responsibilities. Future efforts should focus on the gaps in patient's knowledge to allow the patient to ask the right questions necessary for decision-making.

Adult↗

PubMed2006

Separating structural heterogeneities from stochastic variations in fluorescence resonance energy transfer distributions via photon distribution analysis.

We establish a probability distribution analysis (PDA) method for the analysis of fluorescence resonance energy transfer (FRET) signals to determine with high precision the originating value of a shot-noise-limited signal distribution. PDA theoretical distributions are calculated explicitly including crosstalk, stochastic variations, and background and represent the minimum width that a FRET distribution must have. In this way an unambiguous distinction is made between shot-noise distributions and distributions broadened by heterogeneities. This method simultaneously and effectively extracts highly resolved information from FRET distributions. The theoretical histograms match the exact profile of histograms generated from constant transfer efficiency experimental data with a chi2 near unity. The chi2 surface suggests an ultimate level of precision with FRET of < 1% of the Förster radius. Distributions of FRET signals in donor-acceptor-labeled DNA were unambiguously identified as being broader than shot-noise variations could explain. A model describing a Gaussian distribution of distances was tested with the PDA method and demonstrated 5 A inhomogeneities due to dye motions. The capability of this method to recover quantitative information from FRET distributions has potential applications for studying molecular conformations and dynamics. Potential sources for artifacts such as acceptor photobleaching, spectrally different observation volumes, and fluctuations of the Förster radius are ruled out.

DNA↗

PubMed2002

Diagnosis of the hypothenar hammer syndrome by high-resolution contrast-enhanced MR angiography.

Our objective was to describe the imaging features of hypothenar hammer syndrome using minimally invasive contrast-enhanced MR angiography in comparison with oscillography study. In five patients with hypothenar hammer syndrome Gd-BOPTA-enhanced elliptically reordered 3D pulse sequence MR was compared with oscillography findings and clinical symptoms focusing on angiographic appearance of vessel injury, distribution pattern of hand vasculature and joining branches between the radial and ulnar artery supply. All patients showed segmental occlusion at the site of trauma impact with varying involvement of the superficial palmar arch, common volar digital arteries. Embolic disease was present in 50% of patients and could be clearly identified with MRA. Good correspondence was found between angiographic appearance including the presence of collaterals, clinical symptoms and oscillography. Bilateral comparison was helpful in distinguishing between vessel variants and pathology. Bilateral Gd-BOPTA-enhanced MR angiography is a minimally invasive method to depict clearly the localization and extent of vessel injury in hypothenar hammer syndrome providing valuable information about distribution pattern of hand vasculature and presence of collaterals; however, no flow data can be obtained.

Adult↗

PubMed1997

Three-dimensional morphology and distribution of pallidal axons projecting to both the lateral region of the thalamus and the central complex in primates.

This study presents a three-dimensional analysis of pallido-thalamic axons and axonal endings in the monkey (Macaca mulatta and M. irus). Injections of the anterograde tracer biocytin were made in the dorsal, associative region of the medial pallidum. Numerous axonal endings were observed within the pallidal territory of the lateral region of the thalamus and the central complex. Individual axons were reconstructed from serial sections and traced in three dimensions. Two axons made a collateral branch in the ventral part of the lateral region and ended in the central complex. In the pallidal territory of the lateral region, axons divided several times before ending in different parts of the territory in a 'bunch', a characteristic dense terminal arborization. Axonal endings in the central complex were differently organized. Our data show that associative medial pallidal information is distributed throughout the pallidal territory of the lateral region and the pars media of the central complex by means of individual axons with numerous branches and axonal endings specific to each of the two targets.

Animals↗

PubMed1998

A web access script language to support clinical application development.

This paper describes the development of a script language to support the implementation of decentralized, clinical information applications on the World Wide Web (Web). The goal of this work is to facilitate construction of low overhead, fully functional clinical information systems that can be accessed anywhere by low cost Web browsers to search, retrieve and analyze stored patient data. The Web provides a model of network access to data bases on a global scale. Although it was originally conceived as a means to exchange scientific documents, Web browsers and servers currently support access to a wide variety of audio, video, graphical and text based data to a rapidly growing community. Access to these services is via inexpensive client software browsers that connect to servers by means of the open architecture of the Internet. In this paper, the design and implementation of a script language that supports the development of low cost, Web-based, distributed clinical information systems for both Inter- and Intra-Net use is presented. The language is based on the Mumps language and, consequently, supports many legacy applications with few modifications. Several enhancements, however, have been made to support modern programming practices and the Web interface. The interpreter for the language also supports standalone program execution on Unix, MS-Windows, OS/2 and other operating systems.

Computer Communication Networks↗

PubMed1980

Contraceptive habits in women between thirty and fifty years of age. A comparison of two periods, 1967--69 and 1972--74.

The use of contraception by women 30--50 years of age is presented. The material was composed of participants in the prophylactic investigations for cancer colli uteri in the southern part of Storstøms County, which was first performed in the period 1967--69 and secondly in 1972--74. A total of 17 028 women were examined, of whom 8 234 participated in both surveys. A comparision of the two periods of investigation revealed a significant increase (p<0.01) in the utilization of contraception and in shifting to more effective methods. This improvement was attributed to the increased amount of information about contraceptive methods which was made available in the country. It was observed that a remarkably large percentage of the women did not use contraception, 24.9 per cent among those 30--34 years of age, 26.9 per cent among those 35--39 years of age, 40.7 per cent among those 40--44 years of age and 57.2 per cent among those 45--49 years of age. Analysis of the influence of socioeconomic conditions showed that women of the lowest social stratum, with slight education and low income, made up a large proportion of those who abstained from contraception. The number of pregnancies was found to play a role in the use of contraception. An expansion of the distribution of information about contraception to the public is recommended, as well as a possible economic subsidy to the socially disadvantaged for procurement of contraceptives.

Adult↗