Quasi-steady states in natural displacement ventilation driven by periodic gusting of wind

2012 ◽  
Vol 707 ◽  
pp. 1-23 ◽  
Author(s):  
Richard W. Mott ◽  
Andrew W. Woods

AbstractWe investigate the natural displacement ventilation of a space connected to a body of warm fluid through high- and low-level vents. The space is subject to discrete periodic gusts of wind entering at high level from a cold exterior. The cold exterior air entering the space produces buoyancy differences between the space and the body of warm fluid, driving a ventilation flow. Initially we examine the case of a series of identical gusts of wind modelled as turbulent buoyant thermals. New laboratory experiments show that an approximately two-layer stratification is established and the height of the interface is quasi-steady if the period between thermals is much less than the draining time of the space but longer than the fall time of individual thermals. Experiments also show that the interface height depends on the average buoyancy flux associated with the wind gusts, the time between thermals as well as the geometric properties of the vents. This contrasts with the case of a continuous source of buoyancy where the interface height depends only on the geometric properties of the vents and is independent of the buoyancy flux. We develop a quasi-steady two-layer model of the flow based on the classical theory of turbulent thermals and show that it is consistent with our new experimental data. We generalize the model to explore the sensitivity of the results to temporal variations in the size of thermals. We then extend the model to explore the effects of longer interval times between successive thermals and find a two-layer stratification still develops but that the interface height now varies cyclically in time. We then discuss the implications of these results for the ventilation of a shopping mall subject to gusts of wind.

2019 ◽  
Vol 20 (7) ◽  
pp. 661-665
Author(s):  
Cunxi Nie ◽  
Fei Xie ◽  
Ning Ma ◽  
Yueyu Bai ◽  
Wenju Zhang ◽  
...  

As a major component of biologically active compounds in the body, proteins contribute to the synthesis of body tissues for the renewal and growth of the body. The high level of dietary protein and the imbalance of amino acid (AA) composition in mammals result in metabolic disorders, inefficient utilization of protein resources and increased nitrogen excretion. Fortunately, nutritional interventions can be an effective way of attenuating the nitrogen excretion and increasing protein utilization, which include, but are not limited to, formulating the AA balance and protein-restricted diet supplementing with essential AAs, and adding probiotics in the diet. This review highlights recent advances in the turnover of dietary proteins and mammal’s metabolism for health, in order to improve protein bioavailability through nutritional approach.


Author(s):  
Kiona Hagen Niehaus ◽  
Rebecca Fiebrink

This paper describes the process of developing a software tool for digital artistic exploration of 3D human figures. Previously available software for modeling mesh-based 3D human figures restricts user output based on normative assumptions about the form that a body might take, particularly in terms of gender, race, and disability status, which are reinforced by ubiquitous use of range-limited sliders mapped to singular high-level design parameters. CreatorCustom, the software prototype created during this research, is designed to foreground an exploratory approach to modeling 3D human bodies, treating the digital body as a sculptural landscape rather than a presupposed form for rote technical representation. Building on prior research into serendipity in Human-Computer Interaction and 3D modeling systems for users at various levels of proficiency, among other areas, this research comprises two qualitative studies and investigation of the impact on the first author's artistic practice. Study 1 uses interviews and practice sessions to explore the practices of six queer artists working with the body and the language, materials, and actions they use in their practice; these then informed the design of the software tool. Study 2 investigates the usability, creativity support, and bodily implications of the software when used by thirteen artists in a workshop. These studies reveal the importance of exploration and unexpectedness in artistic practice, and a desire for experimental digital approaches to the human form.


Clay Minerals ◽  
2016 ◽  
Vol 51 (2) ◽  
pp. 223-235 ◽  
Author(s):  
Raúl Fernández ◽  
Ana Isabel Ruiz ◽  
Jaime Cuevas

AbstractConcrete and bentonite are being considered as engineered barriers for the deep geological disposal of high-level radioactive waste in argillaceous rocks. Three hydrothermal laboratory experiments of different scalable complexity were performed to improve our knowledge of the formation of calcium aluminate silicate hydrates (C-A-S-H) at the interface between the two materials: concretebentonite transport columns, lime mortar-bentonite transport columns and a portlandite- (bentonite and montmorillonite) batch experiment. Precipitation of C-A-S-H was observed in all experiments. Acicular and fibrous morphologies with certain laminar characteristics were observed which had smaller Ca/Si and larger Al/Si ratios with increasing temperature and lack of accessory minerals. The compositional fields of these C-A-S-H phases formed in the experiments are consistent with Al/(Si+Al) ratios of 0.2– 0.3 described in the literature. The most representative calcium silicate hydrate (C-S-H) phase from the montmorillonite–cement interface is Al-tobermorite. Structural analyses revealed a potential intercalation or association of montmorillonite and C-A-S-H phases at the pore scale.


2014 ◽  
Vol 664 ◽  
pp. 423-428
Author(s):  
Mauricio Plaza Torres ◽  
William Aperador

Hip disarticulation is an amputation through the hip joint capsule, removing the entire lower extremity, with closure of the remaining musculature over the exposed acetabulum. Tumors of the distal and proximal femur were treated by total femur resection; a hip disarticulation sometimes is performance for massive trauma with crush injuries to the lower extremity. This article discusses the design a system for rehabilitation of a patient with bilateral hip disarticulations. The prosthetics designed allowed the patient to do natural gait suspended between parallel articulate crutches with the body weight support between the crutches. The care of this patient was a challenge due to bilateral amputations at such a high level and the special needs of a patient mobility.


1984 ◽  
Vol 62 (8) ◽  
pp. 1548-1555 ◽  
Author(s):  
Pierre Magnan ◽  
Gérard J. FitzGerald

When brook charr, Salvelinus fontinalis Mitchill, are in allopatry in oligotrophic Québec lakes, they feed largely on macrobenthic invertebrates. However, when brook charr cooccur with creek chub, Semotilus atromaculatus Mitchill, they feed largely on zooplankton. In the present study, laboratory experiments showed that creek chub were more effective than brook charr in searching for hidden, patchily distributed prey. The searching efficiency of an individual chub feeding in a group was improved through social facilitation. In contrast, the high level of intraspecific aggression observed in brook charr prevents the formation of such feeding groups. In the laboratory, brook charr were able to displace creek chub from the food source because of interspecific aggression. Data are presented showing that chub are morphologically better adapted than charr to feed on benthos (subterminal orientation of the mouth and protrusible premaxillae), while the charr are better adapted than chub to feed on zooplankton (gill raker structure). Differences in feeding behaviour, morphology, and relative abundance between these species appear to be important in the observed niche shift of brook charr in nature.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Roberto Pessoa de Queiroz Falcão ◽  
Michel Mott Machado ◽  
Eduardo Picanço Cruz ◽  
Caroline Shenaz Hossein

PurposeThe purpose of this article is to investigate how social integration, immigrant networks and barriers to ventureing affect the entrepreneurial activities of Brazilians in Canada, indicating how mixed embeddedness takes place in that context.Design/methodology/approachData were collected in Toronto, through the application of a survey with 74 Brazilian entrepreneur respondents and 42 semi-structured interviews with selected subjects, thus representing a multi-method approach. The analysis included descriptive statistics from the survey data and a qualitative analysis of the trajectories and life stories of Brazilian immigrants.FindingsOur sample comprises respondents with a high level of education and proficiency in English, coming predominantly from the southeast of Brazil, white, aged from 30 to 49. The majority of businesses are small and related to the service sector. The article contributes to the literature by discussing the elements related to mixed embeddedness, including the need for cultural adaptation and for the creation of networks as a crucial element for business venturing.Research limitations/implicationsThe study focuses on entrepreneurs regardless of their businesses sector or formality/informality status. It could be used as an instrument to support Canadian public policies for welcoming Brazilians and for the Brazilian government to prevent the evasion of potential entrepreneurs.Originality/valueThe article contributes to the body of knowledge of immigrant entrepreneurship in Canada and of Brazilian entrepreneurship overseas. The results suggest factors that may be relevant to the expansion of their business, such as social networking, cultural embeddedness and adaptation of the products/services to a wider range of target customers.


Author(s):  
Beschasnyi S.P. ◽  
Lysenko E.M. ◽  
Hasiuk O.M. ◽  
Erlish О.О.

Carbon monoxide is a toxic gas that is colourless, odourless, and has the potential to cause momentaryhypoxia by bonding with heme-inspired proteins. Because of these properties, it causes the highest number of toxications. Due to its properties, this gas causes damage to the nervous and cardiovascular system. The development of anoxia is associated with the impact on the system of oxidative phosphorylation in mitochondria and the development of oxidative stress in the body. The body produces a small amount of carbon monoxide as a result of erythrocyte breakdown. Picomolar concentrations of carbon monoxide even have anti-inflammatory, antiapoptotic,cytoprotective and antiproliferative properties. Kidney is one of the first organs,that responds to the occurrence of hypoxia, are responsible for the removal of products of metabolism and toxicants, including ethanol. For the study, the blood and urine samples were taken from patients with acute intoxication. The amount of methemoglobin in the blood was determined by spectrophotometric method. The concentration of ethanol in blood and urine was measured by gas-liquid chromatography method. The correlation analysis showed that carbon monoxide affects the rate of excretion of ethanol from the body. Among individuals under 40 years of age, there was a correlation between the level of carbon monoxide and the amount of ethanol in the blood. Among older adults this correlation was not established. A direct correlation with the level of this gas in the blood and the level of ethanol in the urine among people under 40 years of age was found. Among older individuals, the opposite was observed –a high level of methemoglobin was responsible for the decreased level of ethanol. There were no correlations between methemoglobin level and age. Comparison of the studied indices did not show any sexual differences in ethanol excretion, but there were age specific features: ethanol excretion under the influence of carbon monoxide among people under 40 years old was more accelerated.Key words:hypoxia, CO intoxication, blood, methemoglobin, kidneys. Монооксид карбону являє собою токсичний газ, який не має кольору,без запаху та здатен спричиняти миттєву гіпоксію шляхом зв’язування з гем-вмісними білками. Через такі властивості він спричиняє найбільшу кількість отруєнь. Цей газ,завдяки своїм властивостям,спричиняє ураження нервової та серцево-судинної системи. Розвиток аноксії пов’язаний із впливом на систему окисного фосфорилювання у мітохондріях та розвиткомоксидативного стресу. В організмі продукується невелика кількість ендогенного монооксиду карбону внаслідок розпаду еритроцитів. Пікомолярні концентрації монооксиду карбону навіть володіють протизапальними, антиапоптичними, цитопротекторними та антипроліферативними властивостями. Нирки є одним із перших органів, який реагує на розвитокгіпоксії, вони відповідають за видалення продуктів метаболізму й токсикантів, зокрема етанолу.Зміни у функціонуванні нирок відображаються на загальному стані організму.Для дослідження отримували зразки крові та сечі від осіб із гострою інтоксикацією. У крові спектрофотометричним методом визначали вміст метгемоглобіну, який утворювався внаслідок вдихання монооксиду карбону та відповідного потрапляння до кровоносної системи. Методом газово-рідинної хроматографії вимірювали концентрацію етанолу у крові та сечі. Розрахунок кореляційних зв’язків показав, що монооксид карбону впливає на швидкість екскреції етанолу. У осіб до 40 років спостерігалася кореляція між показником рівня метгемоглобінута вмістом етанолу у крові. У осіб старшого віку цього зв’язку не встановлено. Виявлено прямий зв’язок із рівнем цього газу у крові та рівнем етанолу в сечі у осіб до 40 років. У осіб старшого віку спостерігалася зворотня реакція–високий рівень метгемоглобінуобумовлював зниження рівня етанолу. Кореляційні зв’язки між вмістом метгемоглобіну та віком не було виявлено. Порівняння досліджуваних показників не виявило статевих відмінностей у екскреції етанолу, проте виявлено вікові особливості: екскреція етанолу в умовах впливу монооксиду карбону в осіб до 40 років була більш пришвидшена.Таким чином, можна стверджувати, що монооксид карбону обумовлює зміни у функціональній активності нирок.Ключові слова:гіпоксія, інтоксикація СО, кров, метгемоглобін, нирки.


2011 ◽  
Vol 65 (4) ◽  
pp. 403-409 ◽  
Author(s):  
Ruzica Nikolic ◽  
Jasmina Jovanovic ◽  
Gordana Kocic ◽  
Tatjana Cvetkovic ◽  
Svetlana Stojanovic ◽  
...  

Heavy metals as pollutants in the working and living environment are a serious health and environmental problem because they are toxic, non-biodegradable, accumulate in living systems and have a long half-life in soil. Sources of lead contamination are combustion products in the chemical industry and metallurgy, industrial waste water, landfills, traffic etc. Lead enters into the body via the food chain and drinking water. In the body lead is deposited in the liver, kidneys, brain and mineral tissues. Excretion of lead causes damage to the epithelial cells of certain organs. High level exposure to cadmium is usually the result of environmental pollution by human activities. Exposure to cadmium can lead to acute and chronic tissue damage of various organs, including liver and kidneys in humans and in animals. In this paper we analyzed the effects of lead and cadmium exposure, in working and living environment, on the model system of experimental animals, particularly the activity of certain liver enzymes, acid and alkaline DNase, and standard biochemical blood parameters. The study showed that lead and cadmium significantly affect the protein content, red blood cells, hemoglobin and hematocrit, and the activity of liver enzymes. This harmful effect of this toxic metal can be reduced by the supplements.


2009 ◽  
Vol 137 (11-12) ◽  
pp. 659-663 ◽  
Author(s):  
Milan Latas ◽  
Danilo Obradovic ◽  
Marina Pantic

Introduction. A cognitive model of aetiology of panic disorder assumes that people who experience frequent panic attacks have tendencies to catastrophically interpret normal and benign somatic sensations - as signs of serious illness. This arise the question: is this cognition specific for patients with panic disorder and in what intensity it is present in patients with serious somatic illness and in healthy subjects. Objective. The aim of the study was to ascertain the differences in the frequency and intensity of 'catastrophic' cognitions related to body sensations, and to ascertain the differences in the frequency and intensity of anxiety caused by different body sensations all related to three groups of subjects: a sample of patients with panic disorder, a sample of patients with history of myocardial infarction and a sample of healthy control subjects from general population. Methods. Three samples are observed in the study: A) 53 patients with the diagnosis of panic disorder; B) 25 patients with history of myocardial infarction; and C) 47 healthy controls from general population. The catastrophic cognitions were assessed by the Agoraphobic Cognitions Questionnaire (ACQ) and the Body Sensations Questionnaire (BSQ). These questionnaires assess the catastrophic thoughts associated with panic and agoraphobia (ACQ) and the fear of body sensations (BSQ). All study subjects answered questionnaires items, and the scores of the answers were compared among the groups. Results. The results of the study suggest that: 1) There is no statistical difference in the tendency to catastrophically interpret body sensations and therefore to induce anxiety in the samples of healthy general population and patients with history of myocardial infarction; 2) The patients with panic disorder have a statistically significantly more intensive tendency to catastrophically interpret benign somatic symptoms and therefore to induce a high level of anxiety in comparison to the sample of patients with the history of serious somatic illness (myocardial infarction) and the sample of healthy general population. Conclusion. The tendency to catastrophically interpret benign somatic symptoms and therefore to induce a high level of anxiety in patients with panic disorder, confirms the cognitive aetiology model of panic disorder and suggests that it should be the focus of prophylactic and therapeutic management of patients with panic disorder.


2008 ◽  
Vol 136 (5-6) ◽  
pp. 284-288 ◽  
Author(s):  
Nadja Maric ◽  
Dragana Josifovic-Kostic ◽  
Olivera Vukovic ◽  
Dubravka Britvic ◽  
Miroslava Jasovic-Gasic

INTRODUCTION Olanzapine is a second generation antipsychotic (SGA) with a high level of therapeutic effectiveness in schizophrenia and other psychotic disorders. Along with the positive therapeutic effects, an increase of the body weight frequently occurs. According to the literature, the average weight gain is about 6-7 kg during several months of treatment. This could be valued as a moderate weight increase. CASE OUTLINE This article presents a case of a young female with schizophrenia, without clinical improvement with several antipsychotics (clozapine, risperidone, haloperidol) and with the occurrence of significant neurological side effects. The treatment started with olanzapine (baseline) was associated with good initial response (PANSS reduction 20% in the first two weeks) and the improvement was maintained further on (PANSS reduction 50% after 16 weeks). Significant increase (20 kg, 40%) in weight appeared during the following 16 weeks (BMI at baseline 17.9 kg/m2; BMI 16 weeks later 25.1 kg/m2). CONCLUSION High effectiveness of olanzapine in schizophrenia symptoms reduction was accompanied by a significant weight gain. However, this drug leads to impaired glucoregulation, dyslipidaemia etc. It also increases the risk of diabetes and cardio-vascular diseases, i.e. the main causes of mortality in schizophrenia after a suicide. Therefore, clinicians are suggested to focus on possible predictors of weight gain during olanzapine therapy, and act accordingly in order to prevent serious health consequences.


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