Literatura académica sobre el tema "Confined compartment"
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Artículos de revistas sobre el tema "Confined compartment"
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Heasley, Lydia R., Steven M. Markus y Jennifer G. DeLuca. "“Wait anaphase” signals are not confined to the mitotic spindle". Molecular Biology of the Cell 28, n.º 9 (mayo de 2017): 1186–94. http://dx.doi.org/10.1091/mbc.e17-01-0036.
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The spindle assembly checkpoint ensures the faithful inheritance of chromosomes by arresting mitotic progression in the presence of kinetochores that are not attached to spindle microtubules. This is achieved through inhibition of the anaphase-promoting complex/cyclosome by a kinetochore-derived “wait anaphase” signal known as the mitotic checkpoint complex. It remains unclear whether the localization and activity of these inhibitory complexes are restricted to the mitotic spindle compartment or are diffusible throughout the cytoplasm. Here we report that “wait anaphase” signals are indeed able to diffuse outside the confines of the mitotic spindle compartment. Using a cell fusion approach to generate multinucleate cells, we investigate the effects of checkpoint signals derived from one spindle compartment on a neighboring spindle compartment. We find that spindle compartments in close proximity wait for one another to align all chromosomes before entering anaphase synchronously. Synchrony is disrupted in cells with increased interspindle distances and cellular constrictions between spindle compartments. In addition, when mitotic cells are fused with interphase cells, “wait anaphase” signals are diluted, resulting in premature mitotic exit. Overall our studies reveal that anaphase inhibitors are diffusible and active outside the confines of the mitotic spindle from which they are derived.
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Schmidt, Kathleen. "Which Linear Compartmental Systems Can Be Analyzed by Spectral Analysis of PET Output Data Summed over All Compartments?" Journal of Cerebral Blood Flow & Metabolism 19, n.º 5 (mayo de 1999): 560–69. http://dx.doi.org/10.1097/00004647-199905000-00010.
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General linear time-invariant compartmental systems were examined to determine which systems meet the conditions necessary for application of the spectral analysis technique to the sum of the concentrations in all compartments. Spectral analysis can be used to characterize the reversible and irreversible components of the system and to estimate the minimum number of compartments, but it applies only to systems in which the measured data can be expressed as a positively weighted sum of convolution integrals of the input function with an exponential function that has real-valued nonpositive decay constants. The conditions are met by compartmental systems that are strongly connected, have exchange of material with the environment confined to a single compartment, and do not contain cycles, i.e., there is no possibility for material to pass from one compartment through two or more compartments back to the initial compartment. Certain noncyclic systems with traps, systems with cycles that obey a specified loop condition, and noninterconnected collections of such systems also meet the conditions. Dynamic positron emission tomographic data obtained after injection of a radiotracer, the kinetics of which can be described by any model in the class of models identified here, can be appropriately analyzed with the spectral analysis technique.
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Chan, Michael W., Isabelle Thibault, Eshetu G. Atenafu, Eugene Yu, B. C. John Cho, Daniel Letourneau, Young Lee, Albert Yee, Michael G. Fehlings y Arjun Sahgal. "Patterns of epidural progression following postoperative spine stereotactic body radiotherapy: implications for clinical target volume delineation". Journal of Neurosurgery: Spine 24, n.º 4 (abril de 2016): 652–59. http://dx.doi.org/10.3171/2015.6.spine15294.
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OBJECT The authors performed a pattern-of-failure analysis, with a focus on epidural disease progression, in patients treated with postoperative spine stereotactic body radiotherapy (SBRT). METHODS Of the 70 patients with 75 spinal metastases (cases) treated with postoperative spine SBRT, there were 26 cases of local disease recurrence and 25 cases with a component of epidural disease progression. Twenty-four of the 25 cases had preoperative epidural disease with subsequent epidural disease progression, and this cohort was the focus of this epidural-specific pattern-of-failure investigation. Preoperative, postoperative, and follow-up MRI scans were reviewed, and epidural disease was characterized based on location according to a system in which the vertebral anatomy is divided into 6 sectors, with the anterior compartment comprising Sectors 1, 2, and 6, and the posterior compartment comprising Sectors 3, 4, and 5. RESULTS Patterns of epidural progression are reported specifically for the 24 cases with preoperative epidural disease and subsequent epidural progression. Epidural disease progression within the posterior compartment was observed to be significantly lower in those with preoperative epidural disease confined to the anterior compartment than in those with preoperative epidural disease involving both anterior and posterior compartments (56% vs 93%, respectively; p = 0.047). In a high proportion of patients with epidural disease progression, treatment failure was found in the anterior compartment, including both those with preoperative epidural disease confined to the anterior compartment and those with preoperative epidural disease involving both anterior and posterior compartments (100% vs. 73%, respectively). When epidural disease was confined to the anterior compartment on the preoperative and postoperative MRIs, no epidural disease progression was observed in Sector 4, which is the most posterior sector. Postoperative epidural disease characteristics alone were not predictive of the pattern of epidural treatment failure. CONCLUSIONS Reviewing the extent of epidural disease on preoperative MRI is imperative when planning postoperative SBRT. When epidural disease is confined to the anterior epidural sectors pre- and postoperatively, covering the entire epidural space circumferentially with a prophylactic “donut” distribution may not be needed.
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Salvado, Francisco C., Arikson J. Tavares, F. Teixeira-Dias y João B. Cardoso. "Confined explosions: The effect of compartment geometry". Journal of Loss Prevention in the Process Industries 48 (julio de 2017): 126–44. http://dx.doi.org/10.1016/j.jlp.2017.04.013.
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Dwyer, C. Liam, Maximillian C. Soong y N. George Kasparyan. "Chronic Exertional Compartment Syndrome of the Hand: Case Report and Literature Review". HAND 12, n.º 3 (15 de septiembre de 2016): NP43—NP45. http://dx.doi.org/10.1177/1558944716668826.
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Background: Chronic exertional compartment syndrome (CECS) is characterized by activity-induced pain, swelling, and decreased muscle function due to increased pressure and decreased circulation within a confined muscle compartment. Although well-known to occur in the leg, involvement of the hand has rarely been reported in the literature. Methods: We present a 44 year old male with CECS involving bilateral thenar and hypothenar compartments. Symptoms were reproduced on exam by driving screws into wood with a screwdriver. Elevated compartment pressures were confirmed with a hand-held digital device which employs a rigid needle that is readily directed to specific compartments. Results: Selective releases of the thenar and hypothenar compartments were performed under local anesthesia and forearm tourniquet in the ambulatory surgery center. At 3-month follow-up, the patient reported full use of his right hand, including woodworking, with excellent relief of symptoms. At 5 months postoperatively, he underwent identical surgical releases on the contralateral left side, with similar relief. Conclusions: CECS of the hand is a rare condition. Our case is unique among prior reports with regard to pattern of compartment involvement, as well as provocative maneuvers and compartment testing methods employed. This report should help foster clinical suspicion, facilitate diagnosis, and demonstrate success of targeted surgical treatment.
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Armstrong, J. B., P. K. Rose, S. Vanner, G. J. Bakker y F. J. Richmond. "Compartmentalization of motor units in the cat neck muscle, biventer cervicis". Journal of Neurophysiology 60, n.º 1 (1 de julio de 1988): 30–45. http://dx.doi.org/10.1152/jn.1988.60.1.30.
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1. The neck muscle biventer cervicis is supplied by five separate nerve bundles that originate from segments C2-C5 and enter the muscle at different rostrocaudal levels. We have used the glycogen-depletion method to investigate the distribution of muscle fibers supplied by each nerve bundle and also the extent of motor-unit territories supplied by single motoneurons in the C3 segment. 2. Prolonged intermittent stimulation of each nerve bundle produced glycogen depletion in a compartment of muscle fibers that ran only a fraction of the whole-muscle length. The depleted compartment was separated by tendinous inscriptions from adjacent, serially arranged compartments that were supplied by different nerve bundles. Thus the muscle was divided into five in-series compartments, arranged in the same rostrocaudal sequence as the nerves by which they were supplied. 3. Six fast, glycolytic (FG) and five fast, oxidative-glycolytic (FOG) motor units were depleted by repetitive intracellular stimulation of their antidromically identified motoneurons in the C3 segment. The fibers of each motor unit were confined to a striplike subvolume whose cross-sectional area was only 20-40% of that for the whole compartment in which it was located. Single motor units contained an average of 408 extrafusal fibers (range: 262-582 fibers), and these were distributed with an average density of 20 fibers/mm2 in cross sections through their motor domains. No significant differences were found between the numbers or densities of fibers in FG and FOG motor units. 4. The specialized in-series organization of compartments has functional implications because the forces generated by one compartment of motor units must be transmitted through other in-series compartments of muscle fibers rather than directly onto skeletal attachments. The confined distribution of muscle fibers belonging to a single motor unit suggests that an additional level of organization may exist within individual compartments. The implications of these features for the physiological behavior and neural control of biventer cervicis are discussed.
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Wang, Aijuan, Brady Manescau, Khaled Chetehouna, Steve Rudz y Ludovic Lamoot. "Experimental study on the flame extension and risk analysis of a diffusion impinging flame in confined compartment". Journal of Fire Sciences 39, n.º 4 (17 de junio de 2021): 285–308. http://dx.doi.org/10.1177/07349041211015766.
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In this work, an experimental investigation on a diffusion impinging flame in a confined compartment was performed. The objective was to study the influence of confinement on the behavior of a flame impinging the ceiling and to deduce the auto-ignition risk of the smoke produced in the confined compartment. For this, configurations with five confinement levels were constructed by the condition of windows and/or door in the compartment and the variation of the heat release rates was made between 0.5 and 18.6 kW. To evaluate the flame morphology and flame extension length, an image processing method based on the direct linear transformation algorithm and the fire segmentation algorithm was adopted. From the experimental data, it was shown that the heat release rate of 4.6 kW presents a critical value for the flame extension in confined configurations, which corresponds to the equivalence ratio of the enclosure greater than 1, highlighting an under-ventilated environment. In addition, an auto-ignition risk analysis of smoke with unburnt gas in the compartment was carried out. The concentration and temperature of these gases were compared to the lower flammability limits and the auto-ignition temperature. It was observed that there was auto-ignition risk of the smoke under the ceiling, especially in the confined compartment of equivalence ratio greater than 1. Under these conditions, it is possible to have a fire spread to another compartment.
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Yadav, VedPal, Anil Juyal y Sansar Sharma. "Evaluation of lateral closed wedge high tibial osteotomy for medial compartment osteoarthritis". Bangladesh Journal of Medical Science 14, n.º 4 (11 de diciembre de 2015): 389–92. http://dx.doi.org/10.3329/bjms.v14i4.18584.
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Introduction: Osteoarthritis of the knee is a common orthopaedic condition. Medial compartment osteoarthritis results from undue stress on the medial compartment of the knee joint following varus deformity. High tibial osteotomy (HTO) has been a long-standing treatment for osteoarthritis of the medial compartment of the knee. Although knee replacement has gained wide popularity for its treatment, still HTO is a good and cost effective procedure for young patients having good range of motion and uni-compartmental involvement. Objective: To evaluate the results of HTO in medial compartment osteoarthritis. Methods and Material: This study was conducted in a tertiary care teaching hospital of North India over a period of 3 years. The patients with disabling knee pain due to medial compartment osteoarthrosis with genu varus deformity refractory to conservative treatment were treated by High Tibial Osteotomy. Results: Overall 40 patients with medial compartmental osteoarthritis were treated with HTO. Patients were evaluated for the severity of pain as per Visual Analogue Score (VAS). There was satisfactory pain reduction (up to 80%) in most of the patients. Conclusions: HTO is a good procedure for young patients with good range of motion and changes confined to one compartment only.Bangladesh Journal of Medical Science Vol.14(4) 2015 p.389-392
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Songyang Li, Ruowen Zong, Lvyi Chen, Tao Wei y Guangxuan Liao. "Effect of Different Fuels on Confined Compartment Fire". Journal of Fire Sciences 28, n.º 4 (4 de diciembre de 2009): 383–403. http://dx.doi.org/10.1177/0734904109350192.
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Elhadi, Hashim Mohamed. "Effect of Diet Quality and Housing on Water Status in Sudanese Desert Sheep and Goats". Journal of Agricultural and Marine Sciences [JAMS] 15 (1 de enero de 2010): 29. http://dx.doi.org/10.24200/jams.vol15iss0pp29-32.
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Two independent experiments were carried out using Sudanese Desert sheep and goats to investigate water metabolism (total body water, TBW and water turnover, WTO) and internal water compartments using radioactive water (tritium), under natural grazing conditions in a semi-desert area. The second trial was carried out on confined sheep, fed high (Lucerne) and poor quality (desert grasses) diets. The body weights, rectal temperature and water parameters were monitored in both trials and species under the Sudanese summer conditions. The grazing animal’s body weights were reduced compared to confined ones. Hyperthermia was pronounced in goats (9%) compared to sheep (6%). The goat hyperthermia was associated with high water turnover, indicating the poor heat tolerance of this species of high evaporative cooling. The confined animals, however, maintained their body weights and did not show signs of hyperthermia. The poor diet (desert grasses) was associated with reduced water intake whereas the Lucerne was associated with high water turnover and high feed intake. The extracelluar compartment (ECV) was higher with the poor diet but was lower than the grazing group. The intracellular compartment (ICV) was higher in the Lucerne group. The study indicated that Sudanese Desert sheep are more tolerant to high temperatures and grazing system than goats.
Tesis sobre el tema "Confined compartment"
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Wang, Aijuan. "Experimental and numerical investigation of the confinement effect on the impinging flame in a compartment". Electronic Thesis or Diss., Bourges, INSA Centre Val de Loire, 2021. http://www.theses.fr/2021ISAB0002.
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Le phénomène de flamme de diffusion impactant une paroi est fréquent dans les scénarios d’incendie en milieu clos. Celui-ci peut entraîner à avoir des conséquences désastreuses en termes de vie humaine et de biens matériels. En effet, lorsqu'une flamme incidente se produit dans un compartiment, elle peut augmenter le risque de propagation du feu de celui-ci vers une autre pièce à travers une explosion de fumée représentant une menace pour les personnes pié-gées. Afin d’apporter des éléments de compréhension sur le comportement de ce type de flamme, de nombreuses études ont réalisé. Celles-ci se sont intéressées sur des flammes impac-tant un plafond en milieu ouvert ou semi-confiné. Cependant il y a peu, voire aucuns travaux qui se sont penchés sur l’étude du comportement d’une flamme incidente dans un compartiment confiné sous ventilé. Dans l’objectif d’apporter des éléments de compréhension en lien avec l’effet du confinement sur la dynamique d’une flamme impactant un plafond, une étude expé-rimentale et numérique est réalisée dans le cadre de cette thèse.L’ensemble des données a été obtenu à l’aide d’un dispositif expérimental représentant un appartement d’étudiant à échelle réduite.Le banc d'essai est un compartiment représentant une maquette d’appartement à petite échelle (1 :10). La conception et dimensionnement a été réalisée sur la base des lois de simili-tudes. Les niveaux de confinement ont été définis en fonction des ouvertures de l’enceinte et du débit calorifique potentielle. A partir de ces deux paramètres, le niveau de confinement peut être associé à la richesse de l’enceinte. Pour cela, huit débits caloriques différents ainsi que cinq possibilités d’ouvertures ont été proposés. À partir des expériences réalisées avec les huit débits calorifiques et les cinq configurations d’ouvertures, l'effet de confinement sur la dynamique d’une flamme impactant un plafond a été effectué en se basant sur les paramètres physico-chimiques, tels que l'extension de la flamme, l'oscillation de la flamme, la distribution de la température et l'analyse des gaz.De plus, grâce à la modélisation numérique de la flamme impactant le plafond à l’aide du code CFD : Fire Dynamics Simulator (FDS), il a été possible d’apporter des éléments supplé-mentaires dans l’analyse des écoulements réactifs associée à l’interaction flamme paroi en fonc-tion du niveau de confinement. Le choix des modèles numériques a été effectué à partir d’une étude préliminaire visant à justifier la fiabilité et la précision du modèle numérique à reproduire les données expérimentales ainsi que des évolutions obtenues à partir de corrélations empiriques obtenues dans les littératures.A partir des analyses réalisées dans cette étude, il est possible de fournir des éléments de décisions lors de la conception et la mise en place de détecteurs d'incendie au plafond dans un compartiment et également d’aider à une meilleure estimation de la probabilité de propagation du feu lors d'un incendie de compartiment par le biais d’une explosion de fumée riche en gaz imbrûlésThe phenomenon of diffusion impinging flame is common in industrials, leading to disas-trous consequences in terms of life and property. When impinging flame occurs in a compart-ment, it may enhance the risk of fire propagation and pose a greater threat to trapped people. Lots of studies dealt with flame impinging an unconfined or confined ceiling while little work focused on the impinging flame in a confined compartment. With the objective of providing understanding related to the confinement effect on the impinging flame in a compartment, both experimental and numerical studies carried out to build up the framework of this thesis. A compartment model representing a reduced scale (1:10) student compartment was uti-lized based on the scaling law such that a test bench with suitable instrumentations for carrying out measurements was developed. Configurations of five confinement levels were constructed by the condition of windows and door in the compartment and heat release rate (HRR) was var-ied between 0.5 kW and 18.6 kW. Through series of experiments, the confinement effect on the dynamics of flame impinging a ceiling was addressed with physicochemical parameters, such as flame extension, flame oscillation, temperature distribution and gas analysis. In addition, on account of the numerical modeling of flame impinging a ceiling using the CFD code: Fire Dynamics Simulator (FDS), it was possible to provide additional elements in the analysis of reactive flows associated with the flame-wall interaction as a function of the confinement level. The choice of numerical models was made on the basis of a preliminary study aimed at justifying the reliability and precision of the numerical modelling in reproducing the experimental data as well as the empirical correlations obtained in the literatures. From the analyzes in this study, it is possible to provide guidance for fire safety engineering in the field of fire risk assessment and fire protection design of buildings
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Mense, Maxime. "Etude des régimes d'instabilités de combustion basse fréquence lors d'un incendie dans une enceinte mécaniquement ventilée". Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0631/document.
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Lors d’essais de feux d’hydrocarbures liquides dans le dispositif DIVA de l’IRSN, un phénomène oscillatoire basse-fréquence (BF), a été observé. Ce phénomène se manifeste par des fluctuations importantes de la pression dans le local, qui peuvent conduire à une perte de confinement et ainsi favoriser la propagation du feu et le rejet de polluants au-delà du local. Il s’accompagne de déplacements intermittents de la flamme hors du bac. L’étude fine de ce phénomène oscillatoire a tout d’abord consisté à concevoir une maquette à l’échelle 1:4 du dispositif DIVA dans lequel nous avons fait varier différents paramètres. L’analyse des résultats obtenus nous a permis d’identifier différents régimes de combustion, de décrire les mécanismes responsables de l’apparition des oscillations BF et de caractériser les propriétés de ces oscillations (fréquence et amplitude). L’occurrence et la persistance des oscillations BF dépendent essentiellement de l’équilibre, plus ou moins précaire, entre la quantité d’air disponible pour la combustion et le débit d’évaporation du combustible résultant des flux thermiques reçus à sa surface. Une étude numérique exploratoire utilisant le code CFD SAFIR a été ensuite conduite en utilisant le débit d’évaporation mesuré expérimentalement, puis en le calculant à l’aide d’un modèle d’évaporation. Si le code ne permet pas de décrire correctement le déplacement de la flamme hors du bac, il reproduit de façon satisfaisante le comportement oscillatoire BF du feu, en particulier sa fréquence dominanteDuring liquid hydrocarbon fire tests in the DIVA device of IRSN, a low-frequency (LF) oscillatory phenomenon, was observed. This phenomenon manifests itself by large variations of the average pressure in the room, which can lead to a loss of confinement and thus promote the spread of fire and the release of pollutants beyond the local. It is accompanied by intermittent displacements of the flame outside the fuel pan. The fine study of this phenomenon consisted in designing a 1:4 scale model of the DIVA device, allowing us to carry out a very large number of tests, varying some parameters. The analysis of the results obtained allowed us to identify different combustion regimes, to describe the mechanisms responsible for the appearance of the LF oscillations, and to characterize the properties of these oscillations (frequency and amplitude). The occurrence and persistence of LF oscillations essentially depend on the precarious equilibrium between the supply of fresh air and the supply of fuel vapors which results from the heat flux received at its surface. An exploratory numerical study using the CFD code SAFIR was then conducted using both the experimentally measured evaporation rate and that calculated using an evaporation model. The model does not correctly describe the displacements of the flame outside the fuel pan. However, it satisfactorily reproduces the LF oscillatory fire behavior, especially its dominant frequency
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Bofinger, Robin. "Photocontrolled biomimetic communication between molecules and nanosystems in confined compartments". Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR14933/document.
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Cette thèse se focalise sur la synthèse et l'étude de nouvelles molécules photoactives et leurs applications en tant que marqueurs, senseurs moléculaires et récepteurs d’ions photomodulables en milieux aqueux et organisés. Les fluorophores développés sont principalement des dérivés du bore-dipyrométhene (BODIPY), comportant des groupements réactifs (azoture, perfluorophényle), des chaines hydrophobes, ou sont intégrés à un récepteur de calcium biocompatible. Le développement d'architectures auto-assemblées multicompartimentées de type vésicules dans des polymersomes géant y est décrit. Ces architectures ont été utilisées pour la génération de lumière blanche dans un micro-domaine, et constitue un modèle pour l'étude de transfert d'ions calcium entre vésicules localisées dans des polymersomes individuels. Ce transfert entre nano-objets confinés à l'intérieur d'un polymersome géant représente un système prototype de communication cellulaire artificiel rudimentaireThe thesis focuses on the study and design of novel photoactive molecules and their application as labeling agents, fluorescent molecular Ca2+-sensors and photolabile Ca2+-decaging agents in aqueous media and organized supramolecular assemblies. The designed fluorophores are based on boron-dipyrromethene (BODIPY) bearing hydrophobic chains or a reactive group like an azide or a perfluorophenyl moiety. Biocompatible calcium receptors have been prepared harnessing the fluorescence properties of BODIPY, naphthalimide and furan fluorophores. The development of self-assembled multicompartmentalized architectures, namely fluorocarbon vesicles in giant polymersomes is reported and the system has been used to create white light emission in confined microdomains. The Ca2+-based ion transfer ion the confined polymer compartments between individual fluorinated vesicles has been studied. The ion transfer in between vesicles in polymer microcompartments has been established as an artificial prototype system for cellular communication
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Karlsson, Anders. "Fabrication of surfactant-based nano- and microscaled biomimetic compartments for studies of confined chemical reactions /". Göteborg : Göteborg university, 2003. http://catalogue.bnf.fr/ark:/12148/cb40111208d.
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Becerra, Barrios Patricio Raul. "Contributions expérimentales sur l'écoulement au passage d'une ouverture horizontale en convection naturelle : application au désenfumage naturel des bâtiments". Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0257.
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Ce travail de recherche porte sur l’étude de l'écoulement d'échange naturel à travers un évent horizontal situé au plafond d'une enceinte munie d'une ouverture verticale en partie basse. Cet échange est contrôlé à la fois par les effets de flottabilité, dus à une différence de température entre le fluide contenu dans le compartiment et l’extérieur, et par le taux de confinement du compartiment, exprimé par le rapport entre la section d'admission d'air en partie basse aB et celle de l’évent aT. L'écoulement à travers l’évent présente deux régimes caractéristiques, monodirectionnel et bidirectionnel, suivant le rapport des sections des ouvertures. Une étude expérimentale à échelle réduite est conduite en se focalisant sur la problématique du remplissage et de la vidange simultanés d’un local ventilé naturellement avec une source de flottabilité. L’objectif est de caractériser la transition et de faire le lien entre ces deux régimes. D'abord, la zone de transition est déterminée à partir de l’analyse de signaux de température recueillis au sein de l’évent couplée à des observations par nappe laser. Les résultats en régime thermique établi délimitent la zone de transition dans une plage(aB / aT) crit ∈ [0.09, 0.18]. Ensuite, les écoulements au niveau de l’évent sont caractérisés grâce à la technique de vélocimétrie par imagerie de particules stéréoscopique (SPIV, par ses sigles en anglais) sur une large plage du rapport des sections des ouvertures. Sur la base des débits mesurés par SPIV, une modélisation du débit est proposée afin de faire le raccordement entre un régime bidirectionnel pour une condition de confinement (aB / aT = 0) et un régime monodirectionnelThis work focuses on the study of the natural exchange flow through a horizontal vent located on the ceiling of an enclosure with a vertical opening at low-level. This exchange flow is controlled by both the buoyancy effects, due to a temperature difference between the fluid contained in the compartment and the outside, and the containment rate of the compartment, expressed by the ratio of the opening areas, aB in the lower part and aT at the vent. The flow through the vent has two characteristic regimes, unidirectional and bidirectional, depending on the ratio of the opening areas. A small-scale experimental study is conducted focusing on the problem of simultaneous filling and emptying of a naturally ventilated room subject to a source of buoyancy. The purpose is to characterize the transition and to make the link between these two regimes. First, the transition zone between the two types of flow is determined from the analysis of temperature signals collected within the horizontal opening coupled with laser observations. The established thermal results delineate the transition zone in a range of (aB / aT)crit ∈ [0.09,0.18]. Then, the vent flows are characterized using the stereo particle image velocimetry technique (SPIV) over a wide range of the ratio of the opening areas. Based on the flows measured by SPIV, a flow modelling at the vent is proposed to make the connection between a bidirectional regime for a confined condition (aB / aT = 0) and a unidirectional regime
Capítulos de libros sobre el tema "Confined compartment"
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Li, Qiang, Jinmei Li, Shijing Ren y Jiaqing Zhang. "Smoke Filling in a Confined Compartment with Single Ceiling Vent". En Fire Science and Technology 2015, 783–91. Singapore: Springer Singapore, 2016. http://dx.doi.org/10.1007/978-981-10-0376-9_80.
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Yao, Lingling, Noémi Becza, Andrea Maul-Pavicic, Jack Chepke, Greg A. Kirchenbaum y Paul V. Lehmann. "Four-Color ImmunoSpot® Assays Requiring Only 1–3 mL of Blood Permit Precise Frequency Measurements of Antigen-Specific B Cells-Secreting Immunoglobulins of All Four Classes and Subclasses". En Methods in Molecular Biology, 251–72. New York, NY: Springer US, 2024. http://dx.doi.org/10.1007/978-1-0716-3690-9_15.
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AbstractThe B lymphocyte response can encompass four immunoglobulin (Ig) classes and four IgG subclasses, each contributing fundamentally different effector functions. Production of the appropriate Ig class/subclass is critical for both successful host defense and avoidance of immunopathology. The assessment of an antigen-specific B cell response, including its magnitude and Ig class/subclass composition, is most often confined to the antibodies present in serum and other biological fluids and neglects monitoring of the memory B cell (Bmem) compartment capable of mounting a faster and more efficient antibody response following antigen reencounter. Here, we describe how the frequency and Ig class and IgG subclass use of an antigen-specific Bmem repertoire can be determined with relatively little labor and cost, requiring only 8 × 105 freshly isolated peripheral blood mononuclear cells (PBMC), or if additional cryopreservation and polyclonal stimulation is necessary, 3 × 106 PBMC per antigen. To experimentally validate such cell saving assays, we have documented that frequency measurements of antibody-secreting cells (ASC) yield results indistinguishable from those of enzymatic (ELISPOT) or fluorescent (FluoroSpot) versions of the ImmunoSpot® assay, including when the latter are detected in alternative fluorescent channels. Moreover, we have shown that frequency calculations that are based on linear regression analysis of serial PBMC dilutions using a single well per dilution step are as accurate as those performed using replicate wells. Collectively, our data highlight the capacity of multiplexed B cell FluoroSpot assays in conjunction with serial dilutions to significantly reduce the PBMC requirement for detailed assessment of antigen-specific B cells. The protocols presented here allow GLP-compliant high-throughput measurements which should help to introduce high-dimensional Bmem characterization into the standard immune monitoring repertoire.
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Zong, Ruowen, Ruxue Kang, Weifeng Zhao y Changfa Tao. "Experimental Study and Model Analysis of Flashover in Confined Compartments". En Fire Science and Technology 2015, 649–57. Singapore: Springer Singapore, 2016. http://dx.doi.org/10.1007/978-981-10-0376-9_66.
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Benarous, Abdallah, Souhila Agred, Larbi Loukarfi y Abdelkrim Liazid. "On the Thermal Characterization of a Fire Induced Smoke-Layer in Semi-confined Compartments". En Lecture Notes in Mechanical Engineering, 491–501. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-41468-3_41.
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Maynard Smith, John y Eors Szathmary. "The evolution of templates". En The Major Transitions in Evolution. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780198502944.003.0008.
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In this chapter, we discuss the origin and early evolution of genetic replication. The argument is complex, so we start with a brief outline. Section 4.2 discusses the nature of replication. We draw a distinction between simple replicators, limited hereditary replicators and indefinite hereditary replicators. Continued evolution requires indefinite hereditary replicators: it seems that such replicators depend on some form of template reproduction. In section 4.3, we point out that there is an error threshold for the accuracy of replication: for a given total quantity of genetic information—for example, for a fixed number of bases—there is an upper limit on the error rate of replication. If the error rate rises above this limit, natural selection cannot maintain the information. This leads to what we have called Eigen's paradox. In the absence of specific enzymes, replication accuracy is low. Hence the total genome size must be small—almost certainly, less than 100 nucleotides. The genome is therefore too small to code for accurate replication machinery. There is a catch-22 situation: no enzymes without a large genome, and no large genome without enzymes. The next three sections discuss possible solutions to the paradox. Section 4.4 considers populations of replicating RNA molecules. We point out that the dynamics of replication are such as to lead to the stable coexistence of a diverse population, but we do not think that this constitutes a solution to the paradox. Section 4.5 discusses the hypercycle, a particular relationship between replicators that makes it possible for a greater total quantity of information to be maintained with a given accuracy of replication. We argue that the further evolution of hypercycles requires that they be enclosed within compartments, because otherwise they are sensitive to parasitic replicators. We also discuss, rather inconclusively, the possibility that, even in the absence of compartments, cooperation might evolve, by a processes analogous to kin selection, if the components of the hypercycle were confined to a surface. Finally, we discuss an alternative model, the stochastic corrector model. This also depends on the existence of compartments, but emphasizes the importance of stochastic effects arising if there are small numbers of each kind of molecule in a compartment. Essentially, small numbers serve to generate variation upon which selection can act.
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Wijdicks, Eelco F. M. "Cerebellum and Brain Stem Hemorrhages". En The Clinical Practice Of Critical Care Neurology, 241–54. Oxford University PressNew York, NY, 2003. http://dx.doi.org/10.1093/oso/9780195157291.003.0014.
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Abstract Parenchymal hemorrhage in brain structures that make up the posterior fossa poses a unique circumstance. The small confines of this compartment surrounded by a taut tentorium border leave little room for a cerebellar hemor-rhage. Interruption of cerebrospinal fluid circulation quickly follows. Hemorrhages into the cerebellum and brain stem are by all means critical neurologic disorders that require immediate action. In fact, hemorrhage into the cerebellum is a neurosurgical emergency. Deterioration can be rapid in many of these wakeful patients. The decision is often either to evacuate the clot or, alternatively, to place a ventricular drain to manage acute hydrocephalus.
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Kui, Wang. "Silica induced cell damage and the protective effect of aluminium complexes". En Chemistry and Technology of Silicon and Tin, 349–52. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780198555803.003.0026.
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Abstract Silicosis develops when the invading silica particles attack alveolar macrophagocytes, inducing cell damage. The lysosome membrane can be considered as the main target in the first stage of attack. Recently, Japanese and Russian scientists have postulated that the damage is mediated by free radicals which cause lipid peroxidation of the biomembranes and release of lysosomic enzymes. We have demonstrated that living cells respond to an exogenous substance as a multiple target system. Different target molecules are confined to different compartments. Owing to the compartmentalization of reactants, the reactions involved are localized and interrelated, leading to a sequence of events.
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Peterson, Anna L. "Conclusion". En Works Righteousness, 199–212. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780197532232.003.0010.
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The concluding chapter explores some of the features of a practice-based approach to ethical theory. It contends that rather than being isolated in one or another compartment or ignored completely, practice should be, and in fact is, integral to all aspects of ethical theory. Because dominant models do not and cannot take practice seriously, we cannot foreground practice within the usual theoretical confines. To understand practice, we have to reshape ethical theory, and vice versa. We will not find real alternatives unless we put practice front and center. Beginning with practice makes it possible to rethink our vision of ethics at the same time as it demands such a rethinking.
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Mellman, I. "Rab4". En Secretory Pathway, 295. Oxford University PressOxford, 1994. http://dx.doi.org/10.1093/oso/9780198599425.003.0183.
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Abstract Rab4 was first localized to early endosomes by screening subcellular fractions prepared from CHO cells using the original panel of polyclonal anti-rab antibodies prepared by Bruno Goud3 Free-flow electrophoresis fractions were analyzed by immunoblotting, and only antibody to rab4 was found to yield a clear signal in the anodally-shifted fractions that co-migrated with transferrin receptor. This localization was confirmed by immunofluorescence performed on cells (Hela, CHO) stably or transiently transfected with wild type rab4a cDNAs. lmmunoelectron microscopy (immuno-EM) on frozen thin sections is also consistent with an early endosome/recycling vesicle localization4; very little rab4 is detectable on the plasma membrane. Since rab5 has also been localized by immunofluorescence, cell fractionation, and immune-EM to early endocytic compartments (see rab5 entry, p. 295), it has been presumed that rab4 and rab5 are themselves co-localized.
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Regassa Cheneke, Kumama. "Forward Bifurcation and Stability Analysis". En Bifurcation Theory and Applications [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.112600.
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Bifurcation is an indispensable tool to describe the behavior of the system at steady states. Recently, the forward bifurcation showed the existence of both local and global stability of equilibrium points obtained from epidemiological models. It is known that the computing process to show the global stability of endemic equilibrium is tricky. But, in this chapter, we incorporate the principles that support the simplification of computation and give the exact existence of global stability of endemic equilibrium point. The most important issue is the application of forward bifurcation diagram obtained from endemic equilibrium and basic reproduction number. For illustration purposes, the mathematical modeling of HBV transmission dynamics is built in this study. The generated HBV model’s well-posedness is confirmed, and the equilibrium points are determined. Additionally, a next-generation matrix approach is used to calculate the basic reproduction number from infected compartments, and numerical simulations are used to demonstrate the occurrence of forward bifurcation at R0=1. If R0<1, the disease-free equilibrium point is both locally and globally asymptotically stable, and if R0>1, the endemic equilibrium is both locally and globally asymptotically stable. The MATLAB platform is used to facilitate numerical simulation.
Actas de conferencias sobre el tema "Confined compartment"
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Manzini, Giovanni, Ivo Kljenak y Mantas Povilaitis. "Vented Explosion Phenomena: Hydrogen Combustion Benchmark on Confined Vessel Experiments". En 2016 24th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icone24-60584.
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Confined vented explosion is a very complex topic as many parameters affect the phenomena, mainly because the flame front develops from an ignition source and travels through a medium which may involve complex boundary conditions and obstructions of various geometries. Therefore, in the plant safety assessing step, it is important to provide correct estimates of the flame spreading rates as well as overpressures which may result from various explosion initiation scenarios. This will help designers for plant layout optimisation with the aim to minimize the risk associated with those events. Although hydrogen explosion in unvented compartments was often simulated in the past, there were not many opportunities, so far, to simulate explosion in a vented room. With this purpose, a benchmark exercise was organized, based on simple hydrogen combustion experiments, performed in a vented compartment (Chamber for View of Explosion – CVE) at the Scalbatraio laboratory of University of Pisa (Italy). In that activity, many tests were performed by varying the initial hydrogen concentration and the obstacles inside the compartment. The numerical codes used in the benchmark were lumped-parameter (LP) ones (ECART, ASTEC), which remain, for the time being, the customary tools for simulating hydrogen combustion accidents in current NPPs, because of their fast-running calculation capabilities also for large-scale scenarios.
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Junjunan, Soleh F., Khaled Chetehouna, Axel Cablé, Abdulhadi Abdlgwad, Antoine Oger y Romie O. Bura. "STUDY OF HEPTANE POOL FIRE IN WELL-CONFINED MILITARY VEHICLE ENGINE COMPARTMENT". En Proceedings of CONV-22: Int. Symp. on Convective Heat and Mass Transfer June 5 – 10, 2022, Turkey. Connecticut: Begellhouse, 2022. http://dx.doi.org/10.1615/ichmt.2022.conv22.200.
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Zhou, Jin, Jinfeng Mao, Yuliang Huang y Zheli Xing. "Studies on fire behavior in a confined compartment based on reduced-scale experiment". En 2015 International Forum on Energy, Environment Science and Materials. Paris, France: Atlantis Press, 2015. http://dx.doi.org/10.2991/ifeesm-15.2015.256.
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Huang, Gaofeng, Kun Zhang y Jiayun Wang. "Integrity Analysis of Electrical Penetration With Intense Radiation Heat Transfer by Hydrogen Diffusion Flame". En 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-67121.
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While hydrogen release into large compartment from confined compartment, hydrogen diffusion flame is easy to occur. There is intense heat radiation effect on electrical penetration from diffusion flame. Aim to evaluate the influence of diffusion flame on electrical penetration, systematic method is constructed, including computing view factor of electrical penetration, assessment of hot spot of containment vessel and research of heat transfer for electrical penetration. Research results give theory basis for determining location of venting which can generate hydrogen diffusion flame. The method can be extended to use in the influence evaluation of personnel hatch and equipment hatch in the containment vessel.
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Peng, Lan, Xianjia Huang, Jinkai Wang, He Zhu, Ping Yang, Chaoliang Xing y Chunyang Zhao. "A Modified Two-Zone Model for Predicting Heat Release Rate of Pool Fire in a Confined Space". En 2022 29th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/icone29-92422.
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Abstract The heat release rate of the fire source is one of the most important parameters for the fire hazards analysis in nuclear power plants. For a fire in a confined compartment, the oxygen concentration has a critical effect on the fire heat release rate under oxygen-deficient situation. In the present work, a modified two-zone fire model was developed to predict the pool fire heat release rate in the oxygen-deficient situation. A simple model estimating the effect of the oxygen concentration on the fire heat release rate was incorporated into two-zone model, CFAST. Furthermore, the conservation of fuel mass was also taken into consideration. Experimental results from three fire experiments of pool fire under the oxygen-deficient situation in the literature available were used to validate the reliability of the modified two-zone model. The oxygen concentration in the compartment was decreased and became oxygen-deficient condition due to the mechanical ventilation. Compared with the original CFAST model, the accuracy of predicting pool fire under oxygen-deficient situation was increased considerably by the modified model, especially for the pool fire at steady under oxygen-deficient situation. In comparison with the experimental data, the cosine similarities of the three heat release rate curves were all over 0.95 and the max relative error of the burning time was 41.9%, which is significantly lower than that of the original two-zone model prediction.
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Metzger, Lukas y Matthias Kind. "Compartment Method for Dynamic Multi-Scale Simulation of Precipitation Reactors". En ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting collocated with the ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/fedsm2014-21547.
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Precipitation crystallization is one possibility to produce nano-scaled solid particles from the liquid phase. High nucleation and growth rates are generated by mixing two well soluble reactants and their subsequent reaction to a sparingly soluble product. These primary processes can be very fast. Therefore experimental access to internal parameters is given insufficiently due to predominantly very short process times. Computational Fluid Dynamics (CFD) based methods are a promising tool to gain insight into those inaccessible processes. Unfortunately, 3D modeling of complex precipitation reactors poses enormous difficulties and computational costs to CFD especially in the production scale under the aspect of macroscopic flowfields down to microscale modeling of mixing, rheology and particle formation. Therefore, a new methodic approach is presented that is able to handle these complex interactions. Due to local and temporal multiscale complexity, it is not advisable to model the complete apparatus. One basic principle of the methodical consideration is the arrangement of cross-linked compartments to reduce the huge unsimulatable control volume in its complexity and dimensions. Thereby, population balance equations (PBE) are solved, using CFD measured, average state variables, with a discrete one-dimensional High Resolution Finite Volume (HRFV) algorithm. Nevertheless appropriate fundamental kinetics for primary and secondary processes have to be implemented. Besides the new methodic approach, this paper deals with the influence of temporal supersaturation buildup on the product particle distribution. It is shown that important conclusions about the mixing behavior of Confined Impinging Jet mixers (CIJMs) can be drawn by coupling CFD and external population balancing even without any micromixing model. The contribution provides an insight into the methodic approach and first derived results.
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Wang, Wei, Hui Zhang, Rui Yang, Qiuju Ma, Xiaodong Liu, Cong Li y Zhenxiang Tao. "Controlling Effect of Oxygen Concentration on Fire Behavior in Low Air Pressure Cargo Compartment". En ASME 2017 Heat Transfer Summer Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/ht2017-5065.
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Cargo compartment fire has become the major security threat for cruising aircraft, the depressurization measurement could effectively suppress the cargo compartment fire through the reduction of the air pressure and oxygen concentration. The objective of this work is to study fire behavior characteristics in half confined chamber and high altitude laboratory at identical low atmospheric pressure, and explore the controlling effects of air exhaust condition, oxygen concentration. N-heptane pool fire experiments were conducted separately in Langfang low pressure chamber (altitude 50m) and Kangding airport laboratory (altitude 4290m) at 60 kPa air pressure, both assembled ISO-9705, but their gas supplying condition is different. Mass burning rate, gas composition, flame temperature, and radiant heat flux had been measured as the principal characteristic parameters for analysis. This paper reveals the variation characteristics of the fire behavior under different oxygen concentration but identical low atmospheric pressure. The gas composition of the chamber is controlled by the liquid fire and air intake quantity, the oxygen concentration of the chamber decreases with decreasing gas intake quantity. The mass burning rate increases and the mass burning time decreases with the increase of the oxygen concentration. The higher air intake quantity or the higher oxygen concentration could increase cargo compartment fire radiation intensity, and exacerbate the fire further propagation. However, under the low oxygen concentration condition, the liquid fire still have a higher flame temperature above a certain height. The depressurization measurement could increase the flame height and flame temperature may be caused the cabin fire-resistant liners layer is easier to burn through. The more reasonable adjustment of the cargo compartment air exhaust quantity and air pressure is very meaningful for the comprehensive fire suppression of cruising commercial airplanes.
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Railsback, Ben T., Richard M. Ziernicki, Ricky L. Nguyen, Steve D. Knapp y William H. Pierce. "Stand-Up Forklift Egress Times as a Function of Operator Compartment Guarding". En ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-38847.
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A significant hazard related to the use of stand-up lift trucks, or stand-up forklifts, is the hazard of a lower limb crush injury or foot crush due to the opening across the rear of the operator compartment. According to one lift truck manufacturer’s statistics, there have been over 500 accidents that resulted in an injury to the lower limb of the operator in the last 30 years that involved their stand-up lift trucks. [1] Other manufacturers have had similar accidents. The injuries have occurred to the lower limb of the operator due to the close proximity of the operator’s lower limbs to the exterior of the lift truck, and the confined areas that stand-up lift trucks operate in. The operator’s lower limb can become pinned and crushed between the moving lift and another fixed object such as a rack system, a column or another lift truck. Objects, such as a fork tine, can also intrude into the operator compartment, injuring the operator’s lower extremities. The ANSI/ITSDF B56.1, Safety Standard for Low Lift and High Lift Trucks, encourages stand-up lift trucks to be designed with an open compartment to permit easy ingress and egress. [2] According to the standard, the open design allows an operator a free and easy egress from the truck in the event of a tip-over or off-the-dock accident. However, the standard permits the use of additional guarding and enclosure of the operator compartment. Spring loaded doors (or spring assisted closing guards) have been designed, implemented and are available from many manufacturers, but no data has been published regarding the time to open and egress from the operator compartment. Latching doors have also been designed and manufactured, but are not currently available on the market except in the case of trucks equipped with freezer cabs, for operation in refrigerated environments. However, latched doors have been criticized for extending the egress time duration by approximately 1/2 second. This study shows that a spring loaded door can be implemented on a stand-up forklift while only increasing egress time by a negligible amount, 0.05 seconds over an open compartment configuration. Furthermore, this study shows that an optimized latching door, designed by Knott Laboratory engineers, can also be implemented for a stand-up forklift while only increasing egress time by 0.09 seconds. The latching door designed by Knott Laboratory decreases the change in egress time associated with a latched door by a factor of 5. Therefore, the addition of a spring loaded door, or a latching door will not significantly increase operator egress time and provide additional protection to the operator in the event of a collision while still maintaining quick egress.
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Liu, Feng, Zhongning Sun, Haozhi Bian y Ming Ding. "Numerical Investigation on Transport Characteristics of Hydrogen-Air-Steam Mixture Induced by Condensation in the Single Compartment". En 2022 29th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/icone29-90644.
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Abstract Under the severe accident of the nuclear power plant, hydrogen-steam mixture gas will be released into the containment compartments. In this process, there is a strong coupling relationship between mixture gas diffusion and steam condensation on the compartment wall surface. Especially for local compartments with poor connectivity, steam condensation is likely to aggravate the risk of hydrogen accumulation and combustion. This coupling phenomenon, which has not been systematically studied in previous numerical simulations or experiments, is especially complex and needs to be further studied. Moreover, the applicability of mechanistic numerical models for predicting condensation-induced transient gas transport processes also should be further confirmed. In this study, the mechanistic numerical model was evaluated through the transient hydrogen mixing experiment of the THAI facility. Based on the validated model, the transient mass transfer process of the mixture gas induced by condensation in a typical single compartment during the steam-hydrogen release process is studied. Furthermore, the influence of release condition of gas source term, wall sub-cooling on the hydrogen accumulation phenomenon in the compartment was discussed. The conclusion is helpful to further understand the transport behavior of hydrogen-air-steam mixture gas in the local single compartment under the severe accident.
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Huang, Xianjia, Kun Bi, Jun Xiao, Lan Peng, He Zhu y Zihui Zheng. "A Method Evaluating Fire Hazard of Multiple-Layer Cable Tray and its Validation". En 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-66017.
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Multi-layer cable tray fire has special burning characteristics that the cable flame spreads horizontally along cable tray and propagates vertically from bottom layer to upper layer at the same time. With respect of accuracy and speed of calculation, simulation of multi-layer cable tray fire remains a challenge for fire models. In this paper, a method is proposed to simulate multi-layer cable tray fire. By developing a more accurate fire source description, this method can provide accurate simulation for multi-layer cable tray fire rapidly. In this method, Firstly, the heat release rate of each burning cable tray is evaluated by FLASH-CAT model. Based on the results from FLASH-CAT, a more accurate fire source definition for multiple lay cable tray is developed for zone model. Taking account of each burning cable tray considered as one fire source point, zone model is applied to predict the fire dynamics process. In order to validate this method, four-layer cable tray fire experiments and replicated experiments were carried out in a confined compartment. The histories of mass loss rate of cable tray and temperatures at the middle of compartment were recorded during the cable fire. From the replicated experimental results of total mass loss rate, it is concluded that the four-layer cable tray fire experiment has good repetition in this scenario. Vertical temperature profile shows that the fire circumstance generated by multiple-layer cable tray burning can be divided into upper hot layer and lower cool layer, which conforms to the basic assumption of zone model. As a consequence, the zone model can be applied to simulating multiple-layer cable tray fire. By comparing the experimental total heat release rate with predictions, it is found that characteristics of multiple-layer cable tray fire are well captured. On account of good prediction on overall heat release rate for multi-layer cable tray fire, predicted heat release rate for each burning cable layer by FLASH-CAT model is believed to be reliable. Then, each burning cable layer is set as one fire source and the heat release rate of each burning cable layer is input into zone model, respectively. The comparisons between simulations and experimental data show that the predicted upper layer temperature and lower layer temperature agree well with experimental data. As a result, it can be concluded that this method provides reliable prediction for multiple-layer cable tray fire rapidly.
Informes sobre el tema "Confined compartment"
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Eldar, Avigdor y Donald L. Evans. Streptococcus iniae Infections in Trout and Tilapia: Host-Pathogen Interactions, the Immune Response Toward the Pathogen and Vaccine Formulation. United States Department of Agriculture, diciembre de 2000. http://dx.doi.org/10.32747/2000.7575286.bard.
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In Israel and in the U.S., Streptococcus iniae is responsible for considerable losses in various fish species. Poor understanding of its virulence factors and limited know-how-to of vaccine formulation and administration are the main reasons for the limited efficacy of vaccines. Our strategy was that in order to Improve control measures, both aspects should be equally addressed. Our proposal included the following objectives: (i) construction of host-pathogen interaction models; (ii) characterization of virulence factors and immunodominant antigens, with assessment of their relative importance in terms of protection and (iii) genetic identification of virulence factors and genes, with evaluation of the protective effect of recombinant proteins. We have shown that two different serotypes are involved. Their capsular polysaccharides (CPS) were characterized, and proved to play an important role in immune evasion and in other consequences of the infection. This is an innovative finding in fish bacteriology and resembles what, in other fields, has become apparent in the recent years: S. iniae alters surface antigens. By so doing, the pathogen escapes immune destruction. Immunological assays (agar-gel immunodiffusion and antibody titers) confirmed that only limited cross recognition between the two types occurs and that capsular polysaccharides are immunodominant. Vaccination with purified CPS (as an acellular vaccine) results in protection. In vitro and ex-vivo models have allowed us to unravel additional insights of the host-pathogen interactions. S. iniae 173 (type II) produced DNA fragmentation of TMB-8 cells characteristic of cellular necrosis; the same isolate also prevented the development of apoptosis in NCC. This was determined by finding reduced expression of phosphotidylserine (PS) on the outer membrane leaflet of NCC. NCC treated with this isolate had very high levels of cellular necrosis compared to all other isolates. This cellular pathology was confirmed by observing reduced DNA laddering in these same treated cells. Transmission EM also showed characteristic necrotic cellular changes in treated cells. To determine if the (in vitro) PCD/apoptosis protective effects of #173 correlated with any in vivo activity, tilapia were injected IV with #173 and #164 (an Israeli type I strain). Following injection, purified NCC were tested (in vitro) for cytotoxicity against HL-60 target cells. Four significant observations were made : (i) fish injected with #173 had 100-400% increased cytotoxicity compared to #164 (ii) in vivo activation occurred within 5 minutes of injection; (iii) activation occurred only within the peripheral blood compartment; and (iv) the isolate that protected NCC from apoptosis in vitro caused in vivo activation of cytotoxicity. The levels of in vivo cytotoxicity responses are associated with certain pathogens (pathogen associated molecular patterns/PAMP) and with the tissue of origin of NCC. NCC from different tissue (i.e. PBL, anterior kidney, spleen) exist in different states of differentiation. Random amplified polymorphic DNA (RAPD) analysis revealed the "adaptation" of the bacterium to the vaccinated environment, suggesting a "Darwinian-like" evolution of any bacterium. Due to the selective pressure which has occurred in the vaccinated environment, type II strains, able to evade the protective response elicited by the vaccine, have evolved from type I strains. The increased virulence through the appropriation of a novel antigenic composition conforms with pathogenic mechanisms described for other streptococci. Vaccine efficacy was improved: water-in-oil formulations were found effective in inducing protection that lasted for a period of (at least) 6 months. Protection was evaluated by functional tests - the protective effect, and immunological parameters - elicitation of T- and B-cells proliferation. Vaccinated fish were found to be resistant to the disease for (at least) six months; protection was accompanied by activation of the cellular and the humoral branches.
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Cahaner, Avigdor, Sacit F. Bilgili, Orna Halevy, Roger J. Lien y Kellye S. Joiner. effects of enhanced hypertrophy, reduced oxygen supply and heat load on breast meat yield and quality in broilers. United States Department of Agriculture, noviembre de 2014. http://dx.doi.org/10.32747/2014.7699855.bard.
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Original objectivesThe objectives of this project were to evaluate the growth performance, meat yield and quality attributes of broiler strains widely differing in their genetic potential under normal temperature vs. warm temperature (short and long-term) conditions. Strain differences in breast muscle accretion rate, metabolic responses under heat load and, gross and histopathological changes in breast muscle under thermal load was also to be characterized. BackgroundTremendous genetic progress has been made in broiler chicken growth rate and meat yield since the 1950s. Higher growth rate is driven by higher rates of feed intake and metabolism, resulting in elevated internal heat production. Hot rearing conditions negatively affect broiler growth by hindering dissipation of heat and may lead to a lethal elevation in body temperature. To avoid heat-induced mortality, broilers reduce feed intake, leading to depressed growth rate, lower weight gain, reduce breast meat yield and quality. Thus, the genetic potential of contemporary commercial broilers (CCB) is not fully expressed under hot conditions. Major conclusions, solutions, and achievementsResearch conducted in Israel focused on three broiler strains – CCB, Featherless, Feathered sibs (i.e., sharing similar genetic background). Complimentary research trials conducted at Auburn utilized CCB (Cobb 500, Cobb 700, Ross 308, Ross 708), contrasting their performance to slow growing strains. Warm rearing conditions consistently reduced feed intake, growth rate, feed efficiency, body weight uniformity and breast muscle yield, especially pronounced with CCB and magnified with age. Breast meat quality was also negatively affected, as measured by higher drip loss and paler meat color. Exposure to continuous or short-term heat stress induced respiratory alkalosis. Breast muscle histomorphometrics confirmed enhanced myofiber hypertrophy in CCB. Featherless broilers exhibited a significant increase in blood-vessel density under warm conditions. Rapid growth and muscle accretion rate was correlated to various myopathies (white striping, woody and necrotic) as well as to increases in plasma creatinekinase levels. Whether the trigger(s) of muscle damage is loss of cellular membrane integrity due to oxidative damage or tissue lactate accumulation, or to loss of inter-compartmental cation homeostasis is yet to be determined. Based on genome-wide single-nucleotide polymorphism array genotyping, identification of the gene with the recessive mutation Scaleless (sc) facilitated the development a dCAPS assay to discriminate between sc carrier (sc/+) and non-carrier (+/+) individuals. ImplicationsThis project confirmed that featherless broiler strains grow efficiently with high yield and quality of breast meat, even under warm rearing conditions that significantly depress the overall performance of CCB. Therefore, broiler meat production in hot regions and climates can be substantially improved by introducing the featherless gene into contemporary commercial broiler stocks. This approach has become more feasible with the development of dCAPS assay. A novel modification of the PCR protocol (using whole blood samples instead of extracted DNA) may contribute to the efficient development of commercial featherless broiler strains. Such strains will allow expansion of the broiler meat production in developing countries in warm climates, where energy intensive environmental control of rearing facilities are not economical and easily achievable.