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At least 1,261 records · Page 70Linked to original sources
PubMed2003

The effect of sample size and MLP architecture on Bayesian learning for cancer prognosis--a case study.

In this paper we investigate the independent effects of training sample size and multilayer perceptron (MLP) architecture on Bayesian learning to build prognostic models for metastatic breast cancer. We trained two types of Bayesian neural networks on a data set of 1477 metastatic breast cancer patients followed at the Institut Curie using disjoint training sets of sizes k = 50, 100, 200, 300, and 450. The learning performance as measured by an expected loss appeared independent of the two architectures modelling the log hazard function under either proportional or non proportional hazard assumptions, thus indicating that no other sources of nonlinearity besides interactions are present. We found a performance breakdown at k = 50, and no sample size effect for k > or = 100.

Bayes Theorem↗
PubMed1992

[A mathematical model of the vascular architecture and of the distribution of resistances in the coronary tree].

The architecture and resistance distribution of the coronary arteriolar tree downstream 100 mu diameter vessels are still largely unknown, due to technical difficulties in direct visualization. In this study we propose a mathematical model of the architecture and the single vessel resistance distribution of terminal arteriolar vasculature in the beating dog heart, based on the analysis of embolization-induced changes of total coronary resistance. Coronary embolization was performed by injecting several boluses of 15 mu (6 cases) and 25 mu (6 cases) plastic microspheres into the maximally vasodilated (adenosine infusion) left circumflex artery of the open chest dog. The relation between the number of plastic beads progressively injected to embolize 15 mu and 25 mu vessels and the resulting increase in total coronary resistance (occlusion function) was obtained in each experiment. If we consider a binary symmetric vascular tree with i) equal resistance for vessels of the same branching order and ii) optimal ratio between resistance of parent and daughter vessels at all branching sites, the simulation of embolization in such a system shows that the occlusion function of the terminal vessels N in the linear portion between 0 and N/2 occluded vessels has a slope S' which is 5.6 times lower than the slope S" between N/2 and 3/4 N occluded vessels and 3.6 times lower than the S' of the occlusion function of the preterminal vessels. The occlusion function in our experiments has a ratio S"/S' close to that predicted by the model and a ratio between the S' of the 25 mu and that of 15 mu experiments equal to 4.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2004

Allochronic differentiation among Daphnia species, hybrids and backcrosses: the importance of sexual reproduction for population dynamics and genetic architecture.

Seasonal dynamics of the abundance, sexual reproduction and genetic architecture in a Daphnia hyalina-galeata hybrid complex were studied in the large and deep Lake Constance. We found evidence for the occurrence of first and second order hybridization. Our study revealed strong differences between the parental species not only regarding their seasonal dynamics, genetic architecture and diversity, but also their sexual reproductive behaviour. The overwintering D. hyalina showed low genetic diversity, no genetic differentiation during the season, and reproduced sexually in autumn, whereas D. galeata reached higher levels of genetic diversity, reproduced sexually in early summer, and exhibited changes in genetic structure during the season, but was only present from spring to autumn. However, in both species sexual reproduction was a rare event, and daphnids, including hybrids, reproduced predominantly asexually. This allows long-term persistence of hybrids as well without continuing hybridization events. Within all variables studied, F1 and F2 hybrids showed an intermediate pattern, whereas proposed backcross hybrids were more similar to their respective parentals. These differences in phenotype as well as significant differences in pairwise Fst values between parentals suggest that gene flow seems to be relatively low in the Lake Constance hybrid system. We found evidence for unidirectional introgression by backcrossing from D. galeata to D. hyalina and found a decrease in at least one of the proposed introgressed alleles in the hyalina-backcross while the season progressed. Our findings suggest allochronic differentiation within this hybrid population and different microevolutionary trajectories of the parental species, which will be discussed in the light of the ongoing reoligotrophication process of Lake Constance.

Animals↗
PubMed2002

Architectural decisions with respect to the introduction of PACS.

In this paper we report on a study on the possible scenarios for the introduction of PACS that was conducted at the LUMC in 2002 by a workgroup. The results of this study should facilitate the decision on PACS to be taken by the management of the LUMC at a later stage. In this paper our main research question is to what extent the decisions to be made at the introduction of PACS can be derived from an information system architecture in place, and vice versa: how can these decisions help to refine an information system architecture that is still immature.

Computer Systems↗
PubMed2003

Clinical document architecture.

The Clinical Document Architecture (CDA), a standard developed by the Health Level Seven organisation (HL7), is an ANSI approved document architecture for exchange of clinical information using XML. A CDA document is comprised of a header with associated vocabularies and a body containing the structural clinical information.

Europe↗
PubMed1992

Stereoscopic vascular architecture of the adult rat femoral head.

We studied the micro-architecture of the rat femoral head using a corroding casting method described by Murakami in comparison with haematoxylin-eosin preparation and transparent preparation. Stereoscopic architecture of the microvasculature in the femoral head was finely demonstrated. Vessels in the metaphysis and the epiphysis were aggregated to form a lobular-like structure. The lobules were interconnected with each other by a few capillaries. A bigger vessel probably corresponding to a drainage vein was seen crossing the growth plate. Loop formations, from simple hairpin-like loop to a more complex loop with a glomerular-like aspect, were demonstrated in the metaphysis underlying the growth plate as well as in the articular surface of the epiphysis.

Animals↗
PubMed2004

Responses of small intestinal architecture and function over time to environmental factors in a tropical population.

To determine the response of the small intestinal mucosa to environmental conditions, we studied changes in mucosal architecture and function in a longitudinal cohort study in African adults. Over three consecutive years, 238 adults submitted monthly stool samples for parasitologic and bacteriologic analysis and underwent an annual endoscopic jejunal biopsy for mucosal morphometry. Absorption and permeability assays were performed on the same day as the enteroscopy. Variation in mucosal architecture and function was correlated with environmental factors and stool microbiology. The whole cohort had structural and functional evidence of tropical enteropathy, but structure and function were only weakly correlated. There were marked changes over time, and seasonal variation was observed in villous height (16%), xylose recovery (16%), and permeability (28%). Asymptomatic intestinal infections were common. Enteropathy was more severe in participants with Citrobacter rodentium or hookworm ova in the stool sample taken one month before the investigations were performed.

Adult↗
PubMed1992

The molecular architecture of an insect midgut brush border cytoskeleton.

The cytoskeletal apparatus of the vertebrate intestinal brush border (BB) has served as a model system for the actin-based cytoskeleton of nonmuscle cells. In this study, we examine the structural organization and molecular architecture of the BB cytoskeleton expressed in the midgut of lepidopteran larvae, Manduca sexta. Electron microscopy of the midgut of the 5th instar larvae revealed enterocytes with an apical BB surface comparable to that in the vertebrate intestine, with both microvillar (MV) and terminal web (TW) domains, the latter defined by a zone of organelle exclusion directly beneath the MV. As reported previously for the larval dragon fly, the MV contain a bundle of actin filaments, as determined by staining with rhodamine phalloidin (Kukulies, J., et al., Protoplasma 121, 157-162 (1984)) and heavy meromyosin decoration (Komnick, H., J. Kukulies, Zoomorphology 107, 241-253 (1987)). Two-dimensional gel analysis revealed the presence of multiple isoelectric variants of actin with the major isoform corresponding to the non-muscle actin isoform II, expressed in Drosophila. Like the vertebrate BB, the Manduca BB can be isolated intact from enterocytes by mechanical shear. Immunochemical analysis of isolated BB fractions or whole homogenates of midgut revealed proteins of appropriate molecular weight immunoreactive with antibodies to the MV core proteins: BB myosin I, villin and fimbrin, and the TW components: spectrin, myosin II and tropomyosin. Immunocytochemical localization of a subset of these proteins at the light microscopic (spectrin) and electron microscopic (actin, villin, spectrin, myosin II, and tropomyosin) level reveals that the molecular architecture of the Manduca BB cytoskeleton is homologous to that found in vertebrates.

Animals↗
PubMed2004

[Changes of sleep architecture in children with obstructive sleep apnea syndrome].

OBJECTIVE: To explore how obstructive sleep apnea syndrome (OSAS) affects children's sleep architecture. METHODS: Eighty-three children with OSAS were reviewed; every patient was monitored with polysommography for 7 hours at night for 11 parameters, including the number of arousal, snoring index, nadir O(2) desaturation, stage I %, stage II %, show wave sleep (SWS)% and rapid eye movement (REM)%. The basis for diagnosis of OSAS was the widely accepted pediatric diagnostic criteria of apnea/hypopnea index, apnea/ hypopnea index of > 1 episode/hour, nadir O(2) desaturation < 92%. Sleep was scored manually according to the standard set by Rechtschaffen. RESULTS: In OSAS group, the number of arousal was 22.5 +/- 1.4, snoring index was 70.6 +/- 16.5, and/or SaO(2) was (73.8 +/- 1.9)%. OSAS group had increased stage I : (45.8 +/- 2.0)% vs. (2.3 +/- 1.1)%, t = 22.46, P < 0.01 and decreased stage II : (23.9 = 1.7)% vs (47.9 = 4.4)%, t = - 14.18, P < 0.01, SWS (15.6 +/- 1.8)% vs. (21.1 +/- 5.0)%, t = - 3.123, P < 0.01, REM (14.7 +/- 1.5)% VS. (28.2 +/- 4.1)%, T = -8.923, p < 0.01. CONCLUSION: The severity of OSAS relates to changes of sleep architecture in children. Intermittent nocturnal hypoxia secondary to apnea/hypopnea, and frequent electroencephalogram arousals from sleep may result in significant sleep fragmentation. Children with OSAS had learning problems and failure to thrive.

Child↗
PubMed2003

Effect of occupational noise on the nocturnal sleep architecture of healthy subjects.

BACKGROUND & OBJECTIVES: Noise is considered to be a non-specific stressor which generally causes physiological and psychological effects in an individual. Many occupations involve workers being subjected to loud noise levels without adequate protective measures. The study was done to document the changes, if any, in the nocturnal sleep architecture of healthy persons exposed to loud occupational noise during daytime. METHODS: The study was a retrospective cohort design wherein three groups of eight subjects each, exposed to continuous occupational background noise levels of > 75dB for 1-2 years, 5-10 years and > 15 years were selected. Corresponding age and gender matched healthy controls (eight for each group) who worked in a quiet atmosphere were also recruited. All night sleep polysomnography was done on all subjects. In the morning, subjects rated their quality of sleep on a Visual Analogue Scale. RESULTS: There is a strong association between occupational exposure to loud noise and poor sleep efficiency (Relative Risk 2.49; Confidence Interval 1.12 to 5.57; P = 0.01, Fisher's exact test). The group exposed to noise for 1-2 years had a decrease in Total Rapid Eye Movement Time, Non Rapid Eye Movement Time, Slow Wave Sleep Time, Sleep Onset Latency and Total Sleep Time. The other two groups showed lesser number of changes in sleep architecture. Subjectively there was a decrease for sleep continuity in Group I and an increase for sleep onset in Group II. There is no correlation between loudness of noise in the workplace and sleep efficiency. INTERPRETATION AND CONCLUSION: It can be concluded that workers exposed to loud background occupational noise are at an increased risk of having poor quality sleep but adaptation to this effect probably takes place after a few years.

Adult↗
PubMed2004

Effect of occupational noise on the nocturnal sleep architecture of healthy subjects.

BACKGROUND & OBJECTIVES: Noise is considered to be a non-specific stressor which generally causes physiological and psychological effects in an individual. Many occupations involve workers being subjected to loud noise levels without adequate protective measures. The study was done to document the changes, if any, in the nocturnal sleep architecture of healthy persons exposed to loud occupational noise during daytime. METHODS: The study was a retrospective cohort design wherein three groups of eight subjects each, exposed to continuous occupational background noise levels of >75dB for 1-2 years, 5-10 years and >15 years were selected. Corresponding age and gender matched healthy controls (eight for each group) who worked in a quiet atmosphere was also recruited. All night sleep polysomnography was done on all subjects. In the morning, subjects rated their quality of sleep on a Visual Analogue Scale. RESULTS: There is a strong association between occupational exposure to loud noise and poor sleep efficiency (Relative Risk 2.49; Confidence Interval 1.12 to 5.57; P=0.01, Fisher's exact test). The group exposed to noise for 1-2 years had a decrease in Total Rapid Eye Movement Time, Non Rapid Eye Movement Time, Slow Wave Sleep Time, Sleep Onset Latency and Total Sleep Time. The other two groups showed lesser number of changes in sleep architecture. Subjectively there was a decrease for sleep continuity in Group I and an increase for sleep onset in Group II. There is no correlation between loudness of noise in the workplace and sleep efficiency. INTERPRETATION & CONCLUSION: It can be concluded that workers exposed to loud background occupational noise are at an increased risk of having poor quality sleep but adaptation to this effect probably takes place after a few years.

Adult↗
PubMed2004

Design of a patient-centered, multi-institutional healthcare information network using peer-to-peer communication in a highly distributed architecture.

OBJECTIVE: to design a community healthcare information network for all 450,000 citizen in the State of Geneva, Switzerland, connecting public and private healthcare professionals. Requirements include the decentralized storage of information at the source of its production, the creation of a virtual patient record at the time of the consultation, the control by the patient of the access rights to the information, and the interoperability with other similar networks at the national and european level. METHODS: a participative approach and real-world pilot projects are used to design, test and validate key components of the network, including its technical architecture and the strategy for the management of access rights by the patients. RESULTS: a distributed architecture using peer-to-peer communication of information mediators can implement the various requirements while limiting to an absolute minimum the amount of centralized information. Access control can be managed by the patient with the help of a medical information mediator, the physician of trust.

Community Networks↗
PubMed2002

A generic arthroscopy simulator architecture.

Virtual Environments offer considerable potential to improve training for arthroscopic surgery. However, current systems are developed for individual joints, which requires healthcare providers to purchase and maintain multiple environments with differing interfaces and capabilities. This paper describes a generic arthroscopy system architecture that allows the fast development of training environments for any joint, each sharing a common user-interface. The use of the architecture in developing a simple ankle simulator is also described.

Anatomy, Regional↗
PubMed2003

Architecture and tools for open, interoperable and portable EHRs.

Electronic Health Record (EHR) systems provide the kernel application of health information systems and health networks which should be independent of complexity, localisation constraints, platforms, protocols, etc. Based on shared care information systems' requirements for high level interoperability, a generic component architecture has been introduced. For implementing, running and maintaining acceptable and useable health information systems components, all views of the ISO Reference Model--Open Distributed Processing have to be considered. Following the Model Driven Architecture paradigm, a reference model as well as concept-representing domain models both independent of platforms must be specified, which are combined and harmonised as well as automatically transferred into platform-specific models using appropriate tools.

Access to Information↗
PubMed2004

[Clonal architecture and ramet population characteristics of Lysimachia congestiflora growing under different light conditions].

The response of clonal architecture and ramet population characteristics to resource heterogeneity is of great ecological significance. This paper studied the variations of clonal architecture and ramet population characteristics of stoloniferous herb Lysimachia congestiflora growing at the open land of forest edge, forest edge, and forest understory of evergreen broad-leaved forest in Mt. Lingyan of Dujiangyan, Sichuan Province, and compared the stolon internode length, frequency distribution of stolon internode length, braching intensity, branching angle, frequency distribution of branching angle, ramet population density, ramet population height, ramet population biomass, and root/shoot of ramet population among the three habitats. The results showed that the stolon internode length, branching intensity, ramet population density and ramet population biomass were different among three habitats. Kruskal Wallis test indicated that the distributions of stolon internode length and branching angle were significantly different among three habitats. The skewness in distribution of stolon internode length was in the order of open land of forest edge>forest edge>forest understory; and the branching angle, ramet population height, and root/shoot of ramet population were significant greater in open land of forest edge than in forest edge and forest understory. The skewness in distribution of branching angle in open land of forest edge was smaller than that in forest edge and forest understory. The branching angle, ramet population height, and root/shoot of ramet population were not significantly different between forest edge and forest understory. These results were discussed in the context of resource acquisition strategy by clonal plants.

Analysis of Variance↗
PubMed1992

Alteration of elastic architecture in the lathyritic rat aorta implies the pathogenesis of aortic dissecting aneurysm.

Weanling Sprague-Dawley rats received beta-aminopropionitrile (BAPN) and/or hypertensive treatment, namely, heminephrectomy and administration of deoxycorticosterone acetate-NaCl. The BAPN-treated rats (lathyritic rats) died of dissecting aneurysm, and the victims with hypertensive treatment was greater in number and died earlier than those without the treatment, indicating that the rise of blood pressure promoted the onset of dissecting aneurysm. The elastic architecture of the ascending aortic media was examined not only by transmission electron microscopy with tannic acid stain and/or toluidine blue O stain, but also by scanning electron microscopy after hot formic acid treatment, and the area of interlaminar elastic fibers were morphometrically analyzed by a point counting method using transmission electron microscopic photographs. In the lathyritic rats, interlaminar elastic fibers showed a significant reduction compared with the control rats, and elastic fibers tended to become round-shaped and were frequently spotted with glycosaminoglycan, which suggest a disturbance of elastogenesis. On the other hand, elastic laminae were not disrupted and smooth muscle cells were well preserved. These results suggest that the alteration of the elastic architecture causes an unstable connection between each elastic lamina, and is related to the initiation and the progression of dissecting aneurysm.

Aminopropionitrile↗
PubMed1992

The multi-trellis software architecture and the intelligent cardiovascular monitor.

A real-time, intelligent cardiovascular monitor is complex. It must process multiple waveforms, recognize artifacts, extract pertinent parameters, recognize a patient's clinical state, analyze the problem and formulate a response. This paper presents the multi-trellis (a collection of process trellises), a software architecture for building such a monitor. A process trellis is a uniform hierarchical framework for heterogeneous program modules. The multi-trellis extension allows one to compile several process trellis programs with widely varying run-time requirements into a single executable program that it is efficient, predictable and usable. Our prototype consists of two process trellises. The lower trellis contains processes to analyze three different analog signals: the blood pressure from a non-invasive monitor and an arterial catheter, and the ECG. The upper trellis contains processes to help detect evolving hemodynamic trends, identify abnormalities, and present a succinct summary to the clinician. Our prototype shows that the multi-trellis is a demonstrably useful software architecture for building these real-time, intelligent monitors.

Artificial Intelligence↗
PubMed1992

Three-dimensional architectures of peritoneal endometriosis.

OBJECTIVE: To elucidate some biological characteristics of peritoneal endometriosis. DESIGN: A recently advanced stereographic computer technology was applied for the investigation of the three-dimensional (3-D) architectures of peritoneal endometriosis. SETTING: University Hospital of Gynecology. PATIENTS: Biopsies were taken from 42 women with peritoneal endometriosis. Twenty-six of them were in the luteal phase. Seventeen of them received Zoladex (ICI, Cambridge, United Kingdom) for 12 weeks before biopsy. RESULTS: Two different main types could be identified according to the presence or absence of ramifications. The apparently multifocal occurrence (in 2-D) of glandular epithelium was not confirmed by the 3-D study that showed that all epithelial glands are interconnected by luminal structures in each peritoneal lesion. Stereometric study suggests a stronger effect of gonadotropin-releasing hormone agonist therapy on the stroma than on the epithelium. CONCLUSIONS: The study evaluated the 3-D architectures of peritoneal endometriosis and identified two principal types of peritoneal endometriosis.

Biopsy↗