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Results for “passive adaptation”

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At least 109 records · Page 6Linked to original sources
PubMed1997

Stabilization investment template for direct casting connection of implant framework segments.

This article presents a procedure whereby a template made of casting investment is used to stabilize a sectioned implant framework that has been adapted in a passive relationship to the implant analogs in a corrected master cast. The joints in the sectioned framework are filled with wax, sprues attached, and the template and sectioned framework are invested in a casting ring. When the casting procedure is completed, the framework will be reconnected by direct metal casting.

Dental Casting Investment↗
PubMed2006

Loss tolerance in one-way quantum computation via counterfactual error correction.

We introduce a scheme for fault tolerantly dealing with losses (or other "leakage" errors) in cluster state computation that can tolerate up to 50% qubit loss. This is achieved passively using an adaptive strategy of measurement--no coherent measurements or coherent correction is required. Since the scheme relies on inferring information about what would have been the outcome of a measurement had one been able to carry it out, we call this counterfactual error correction.

Journal Article↗
PubMed2003

Population monitoring in support of a rabies vaccination program for skunks in Arizona.

Three population monitoring methods were evaluated in support of a trap/vaccinate/release program for controlling a bat variant of rabies virus in skunks (Mephitis mephitis) in Flagstaff, Arizona (USA). Skunks were the primary species targeted for population monitoring during the program, but feral cats were also monitored as they represented an abundant secondary vector species capable of rabies transmission. Skunks were vaccinated and released, except for a subset tested for rabies. All captured cats were placed in the local animal shelter. Spotlight surveys essentially did not detect skunks, and were not able to detect reductions in the cat population. Catch-per-unit-effort marginally tracked population trends, but a passive track index adapted for an urban setting was most sensitive for detecting changes in skunk and cat populations. Mark-recapture population estimates could not be validly calculated from the data on captures and recaptures due to multiple violations of analytical assumptions.

Administration, Oral↗
PubMed2001

Quantitative microvascular corrosion casting by 2D- and 3D-morphometry.

As a system of tubes (blood vessels) the cardiovascular system changes actively and passively diameters to adapt its transport capacities for respiratory gases, nutrients, heat, metabolites and waste products to and off the body's organs, tissues and cells. In most healthy organs blood vessels form a hierarchically arranged three-dimensional network with the geometry defined by vessel diameters, interbranching distances (defining branching frequencies and number of branching sites, i.e. nodes), intervascular distances, and branching angles. In the present study 2D- and 3D-morphometry is applied to quantify these parameters and their changes as they occur in resin casts during metamorphosis of the tadpole lung (2D-morphometry) and filter apparatus vasculature (3D-morphometry). It is shown that 2D-morphometry should be limited to the analysis of high powered images of flat two-dimensional vascular networks (example: tadpole lung alveolar vascular bed) to prevent underestimation of parameters. In contrast, 3D-morphometry can be applied over a wide range of magnifications whereby accuracy of measurements increases with the portion the structure to be measured occupies within the field of view. Together with a careful control of precasting conditions (application of vasoactive drugs, anaesthetics), casting conditions (pressure during rinsing and casting, amount of final shrinkage of casting media), and postcasting conditions (thermal burdening during maceration, sputtering, evaporation, and SEM inspection; thickness of conductive metal layers) 3D-morphometry enables to gain reliable data from resin casts of highly complex real vascular networks in healthy and diseased organs in the developing, juvenile, adult and aged state, as well as in different physiological states.

Aging↗
PubMedDate not supplied

[Analysis of the negotiation/accommodation concepts of M. Leininger's theory].

This work aims at clarifying the method of implementation of the negotiation/accommodation care preconized by Madeleine Leininger's theory concerning the Universality and Diversity of Care. The conceptual analysis technique is used as a tool to analyze the literature. It was verified that the concept of accommodation defines the idea of adaptation, of something passive, whilst in negotiation, each party commands resources and needs to be fulfilled. Among the different works which were analyzed and used Leininger's theory, only one showed to approach negotiation. As a conclusion, accommodation is considered to be different from negotiation, the former being more commonly seen in practice than the latter.

Negotiating↗
PubMed2004

[Dynamics of hypothalamic CRH immune reactivity in active and passive rats in the course of development of behavioural depression].

A possible relation between activity of the main CRH-producing centers of hypothalamus and depressive-like behavior of animals was studied. We used genetically selected strains--KHA (Koltushi High Avoidance) and KLA (Koltushi Low Avoidance) rats, demonstrating active and passive strategy of adaptive behavior in novelty situaltions, respectively. Rats were exposed to inescapable stress to develop a "learned helplessness". We observed considerable differences between two strains of animals in CRH-expression in parvo-, magno-cellular parts of the paraventricular nucleus and in the supraoptic nucleus in the course of behavioral depression development. Significant differences between control groups were seen only in paraventricular nucleus. On the 1st post-stress day in hypothalamus of KLA rats, we detected decreased CRH immune reactivity that remained unchanged up to the 10th day. In KHA rats, there were no notable changes of CRH expression in all studied nuclei. These findings, including previous results on different dynamics of behavioral changes and different hypothalamo-pituitary-adrenocortical system activity during development of depression in KLA and KHA rats, indicate that "learned helplessness" in these two groups of animals provides the model analogues of different types of depression. Besides, these findings indicate different implication of hypothalamus CRH-system in the behavioral depression development in rats with divergent strategy of adaptive behavior.

Adaptation, Psychological↗
PubMed2001

[Impression technics in implantology].

The implant-borne prostheses have become an integral part of the oral rehabilitation procedures. The aim of this article is to describe the most current impression techniques for oral implant prosthetics used at the University of Liège, Belgium. Impression protocols adapted to various prosthetic procedures are described step-by-step through several clinical cases. Emphasis is put on the means necessary for achieving a precise adaptation and a passive fit of the final prosthetic suprastructure.

Cementation↗
PubMedDate not supplied

[Sodium oxybutyrate normalizes the central nervous system functions in the progeny of rats subjected to hypobaric hypoxia during pregnancy].

Two-hour hypobaric hypoxia of rats on day 15 of their pregnancy led to a reduction in weight gain of pups within 20 days after birth, disturbed memory in active and passive paradigms, changed adaptive behavior in the extrapolatory water avoidance test, and impaired sleep in adult animals. Postnatal treatment with sodium hydroxybutyrate given in a dose of 50 mg/kg/day on days 8 to 20 of life normalized mnestic functions of the brain, the process of falling asleep, and physical development which had been impaired by intrauterine hypoxia.

Animals↗
PubMedDate not supplied

Conflicts of thermal adaptation and fever--a cybernetic approach based on physiological experiments.

Cold adaptation aims primarily at a better economy, i.e., preservation of energy often at the cost of a lower mean body temperature during cold stress, whereas heat adaptation whether achieved by exposure to a hot environment or by endogenous heat produced by muscle exercise, often brings about a higher efficiency of control, i.e., a lower mean body temperature during heat stress, at the cost of a higher water loss. While cold adaptation is beneficial in a cold environment, it may constitute a detrimental factor for exposure to a hot environment, mainly because of morphological adaptation. Heat adaptation may be maladaptive for cold exposure, mainly because of functional adaptation. Heat adaptation clearly is best suited to avoid higher body temperatures in fever, no matter which environmental conditions prevail. On the other hand, cold adaptation is detrimental for coping with fever in hot environment. Yet, in the cold, preceding cold adaptation may, because of reduced metabolic heat production, result in lower febrile increase of body temperature. Apparently controversial effects and results may be analyzed in the framework of a cybernetic approach to the main mechanisms of thermal adaptation and fever. Morphological adaptations alter the properties of the heat transfer characteristics of the body ("passive system"), whereas functional adaptation and fever concern the subsystems of control, namely sensors, integrative centers and effectors. In a closed control-loop the two types of adaptation have totally different consequences. It is shown that the experimental results are consistent with the predictions of such an approach.

Acclimatization↗
PubMed1987

[Noradrenaline content of the brain of rats of various ages following adaptation to a new situation and to the development of a passive avoidance conditioned reflex].

Noradrenaline (NA) levels in cortico-striatal (including cerebral cortex, hippocamp, striatum) and hypothalamo-brainstem (including hypothalamus, thalamus, tectum + tegmentum) regions were determined by fluorometry in I- and 2-month-old male rats after 7-day adaptation to experimental conditions and passive avoidance learning by single electric foot shock. Neither the new environment nor a week's adaptation to it resulted in any significant alteration of NA content in both brain regions of 1- and 2-month-old rats. No considerable differences in NA levels were found in rats of both age groups with and without passive avoidance responses. But 24 hours after the exposure to foot shock NA basal levels markedly decreased in both brain regions of 1-month-old rats, while in 2-month-old ones NA basal levels markedly increased in hypothalamo-brainstem region.

Adaptation, Physiological↗
PubMed2005

A new method for measuring passive length-tension properties of human gastrocnemius muscle in vivo.

The study of muscle growth and muscle length adaptations requires measurement of passive length-tension properties of individual muscles, but until now such measurements have only been made in animal muscles. We describe a new method for measuring passive length-tension properties of human gastrocnemius muscles in vivo. Passive ankle torque and ankle angle data were obtained as the ankle was rotated through its full range with the knee in a range of positions. To extract gastrocnemius passive length-tension curves from passive torque-angle data it was assumed that passive ankle torque was the sum of torque due to structures which crossed only the ankle joint (this torque was a 6-parameter function of ankle joint angle) and a torque due to the gastrocnemius muscle (a 3-parameter function of knee and ankle angle). Parameter values were estimated with non-linear regression and used to reconstruct passive length-tension curves of the gastrocnemius. The reliability of the method was examined in 11 subjects by comparing three sets of measurements: two on the same day and the other at least a week later. Length-tension curves were reproducible: the average root mean square error was 5.1+/-1.1 N for pairs of measurements taken within a day and 7.3+/-1.2 N for pairs of measurements taken at least a week apart (about 3% and 6% of maximal passive tension, respectively). Length-tension curves were sensitive to mis-specification of moment arms, but changes in length-tension curves were not. The new method enables reliable measurement of passive length-tension properties of human gastrocnemius in vivo, and is likely to be useful for investigation of changes in length-tension curves over time.

Adult↗
PubMed1993

Subdivision of primary afferents from passive cat muscle spindles based on a single slow-adaptation parameter.

38 primary afferents originating from de-efferented cat tibialis anterior muscle spindles were investigated. Ramp-and-hold stretches of the host muscle were performed with a varying amount of muscle pre-stretch while recording the primary afferent discharges. From the discharge responses an interspike interval function was estimated. This revealed a slow adaptation during the hold phase of stretch which could be approximated quite well by a power function. The slow-adaptation power function exponent (SAE) was found to be rather independent of the amount of pre-stretch applied to the host muscle and grouped around a value characteristic for each afferent. These 'characteristic SAEs' showed a clearly bimodal distribution within the population of primaries studied. Moreover, the distribution around both modes was narrow enough to justify the subdivision of the primary afferents according to their characteristic SAE as either high-SAE (10 afferents; 26%) or low-SAE (28 afferents; 74%) afferents. The most likely explanation for this bimodality of slow-adaptation behavior in primary afferents is given by the assumption that the afferent discharge of the passive spindle is mainly provided from a branch innervating either the bag1 (for high-SAE units) or the bag2 and chain (for low-SAE units) intrafusal fibers.

Action Potentials↗
PubMed2000

Evaluation of assays for determination of passive transfer status in neonatal llamas and alpacas.

OBJECTIVE: To evaluate several practice-adapted assays for determination of passive transfer status in crias. ANIMALS: 24 llama and 9 alpaca crias. DESIGN: Prospective study. PROCEDURE: Serum IgG concentration was measured by use of a radial immunodiffusion assay when crias were 45 to 51 hours old. Results were compared with serum gamma-glutamyltransferase (GGT) activity, serum total protein, albumin, globulin, and total solids concentrations, and results of commercially available and traditional sodium sulfite turbidity (SST) tests. RESULTS: Mean (+/- SD) serum IgG concentration was 1,762 +/- 1,153 mg/dl. On the basis of a threshold value of 1,000 mg of IgG/dl at 48 hours of age, 5 of 33 (15.15%) crias had failure of passive transfer. Serum total solids, protein, and globulin concentrations were significantly associated with serum IgG concentration, whereas serum GGT activity and serum albumin concentration were not. Serum IgG concentrations were significantly different among crias with negative, 2+, and 3+ scores on the traditional SST test. Serum IgG concentrations were not significantly different between crias with negative and 100 mg/dl scores or 100 and 300 mg/dl scores on the commercially available SST test. However, all other comparisons between crias with different scores revealed significant differences. Sensitivity and specificity ranged between 0 and 1, depending on the test and endpoint selected. CONCLUSIONS AND CLINICAL RELEVANCE: The commercially available SST test and determination of serum total protein and globulin concentrations are suitable methods for assessing passive transfer status in llama and alpaca crias.

Animals↗
PubMed1984

The effect of a choice alternative on sex differences in passive avoidance behavior.

A modified standard passive avoidance conditioning procedure was used to investigate whether or not "inferior" passive avoidance behavior of female Wistar rats could be attributed to memory deficits. Male and female Wistar rats were first adapted to two standard passive avoidance conditioning compartments, which were clearly different from one another. Both compartments were accessible from the same illuminated platform. Three learning trials in one compartment were alternated with three trials in the other compartment and unavoidable shock was presented on the last (6th) learning trial in one of the compartments. One hour after shock presentation, subjects were again placed on the platform. Significantly more females than males reentered one of the compartments. Of the subjects which reentered , significantly more females and males than would have been expected by chance, entered the compartment in which shock had not been presented. The data are interpreted to show that sexual dimorphism in passive avoidance behavior should not be attributed to differences in memory capacities of male and female rats. Therefore, it remains to be determined which variables associated with hormonal or genetic background of the subjects and which requirements of the experimental task, are responsible for the occurrence of the observed difference.

Animals↗
PubMed1977

[Hog cholera virus: influence of colostral passive antibody on immune response of pig following vaccination with the rabbit adapted Chinese strain (author's transl)].

Using the rabbit adapted chinese strain of Hog cholera, active immunization of piglets having passive colostral antibodies was studied. 65 piglets born from 11 sows were used. Concerning sows, vaccination was performed 5-6 months and 1 month before service (3 sows), 30 days (2 sows) and 60 days (3 sows) after service. Divided in 5 lots, piglets were vaccinated at 4 different periods after birth (15, 30, 60 and 90 days). Hog cholera immunity was determined for each animal by means of kinetic of serum neutralizing antibodies and resistance to virulent challenge performed 5 months after birth. High levels of neutralizing antibodies were observed in serum of each vaccinated sow at the time of farrowing. In piglets having ingested low quantities of colostrum, vaccination induces a good antigenic stimulation characterized by a normal humoral immune response and challenge resistance. But in piglets having ingested a normal quantities of colostrum, colostral passive antibodies have a partial or complete suppressive effect on primary immune response which is characterized by a delay in serum antibodies formation and by a low level at the time of challenge. According the conditions of sows vaccination, differences were observed in the properties of colostral passive antibodies (intensity of suppressive effect on active immune response, in vitro "avidity" for Hog cholera virus, mean value of half-life) present in piglets serum. On practical aspect, vaccination with the chinese strain becomes fully effective in piglets having passive immunity when they are 30-60 days old.

Animals↗
PubMed2004

Interferometric microwave radiometers for high-resolution imaging of the atmosphere brightness temperature based on the adaptive Capon signal processing algorithm.

Passive microwave remote sensing from satellites and ground stations has contributed uniquely, and substantially, to the study of atmospheric chemistry, meteorology, and environmental monitoring. As user requirements are raised, in terms of the accuracy and the spatial resolution, a mechanically scanning radiometer, with a real aperture, becomes impractical due to the requirement for a very large antenna size. However, an aperture synthesis interferometric radiometer presents a valuable alternative. The work presented in this paper was devoted to high spatial resolution imaging, using the 37 GHz band interferometric radiometer, developed by ourselves. The spatially adaptive Capon beamforming method was exploited for the imaging, which outperformed the conventional Fourier Transform method. We concluded that the high spatial resolution imaging of the brightness temperature of the atmosphere could be accomplished with an interferometric radiometer equipped with the developed Capon beamforming imaging algorithm.

Air Pollutants↗
PubMed2006

Deconstructing adaptive management: criteria for applications to environmental management.

The concept of adaptive management has, for many ecologists, become a foundation of effective environmental management for initiatives characterized by high levels of ecological uncertainty. Yet problems associated with its application are legendary, and many of the initiatives promoted as examples of adaptive management appear to lack essential characteristics of the approach. In this paper we propose explicit criteria for helping managers and decision makers to determine the appropriateness of either passive or active adaptive-management strategies as a response to ecological uncertainty in environmental management. Four categories of criteria--dealing with spatial and temporal scale, dimensions of uncertainty, the evaluation of costs and benefits, and institutional and stakeholder support--are defined and applied using hypothetical yet realistic case-study scenarios that illustrate a range of environmental management problems. We conclude that many of the issues facing adaptive management may have less to do with the approach itself than with the indiscriminate choice of contexts within which it is now applied.

Conservation of Natural Resources↗