18 resultados para Flotation Bubbles
em BORIS: Bern Open Repository and Information System - Berna - Suiça
Resumo:
We generalize uniqueness theorems for non-extremal black holes with three mutually independent Killing vector fields in five-dimensional minimal supergravity in order to account for the existence of non-trivial two-cycles in the domain of outer communication. The black hole space-times we consider may contain multiple disconnected horizons and be asymptotically flat or asymptotically Kaluza–Klein. We show that in order to uniquely specify the black hole space-time, besides providing its domain structure and a set of asymptotic and local charges, it is necessary to measure the magnetic fluxes that support the two-cycles as well as fluxes in the two semi-infinite rotation planes of the domain diagram.
Resumo:
The aim of this article is to disclose the characteristics of postmortem forensic imaging; give an overview of the several possible findings in postmortem imaging, which are uncommon or new to clinical radiologists; and discuss the possible pitfalls. Unspecific postmortem signs are enlisted and specific signs shall be presented, which are typical for one cause of death. Unspecific signs. Livor mortis may not only be seen from the outside, but also inside the body in the lungs: in chest CT internal livor mortis appear as ground glass opacity in the dependent lower lobes. The aortic wall is often hyperdense in postmortem CT due to wall contraction and loss of luminal pressure. Gas bubbles are very common postmortem due to systemic gas embolism after major open trauma, artificial respiration or initial decomposition; in particular putrefaction produces gas bubbles globally. Specific signs. Intracranial bleeding is hyperattenuating both in radiology and in postmortem imaging. Signs of strangulation are hemorrhage in the soft tissue of the neck like skin, subcutaneous tissue, platysma muscle and lymph nodes. The "vanishing" aorta is indicative for exsanguination. Fluid in the airways with mosaic lung densities and emphysema (aquosum) is typical for fresh-water drowning.
Resumo:
We investigated vapor bubbles generated upon irradiation of gold nanoparticles with nanosecond laser pulses. Bubble formation was studied both with optical and acoustic means on supported single gold nanoparticles and single nanoparticles in suspension. Formation thresholds determined at different wavelengths indicate a bubble formation efficiency increasing with the irradiation wavelength. Vapor bubble generation in Bac-1 cells containing accumulations of the same particles was also investigated at different wavelengths. Similarly, they showed an increasing cell damage efficiency for longer wavelengths. Vapor bubbles generated by single laser pulses were about half the cell size when inducing acute damage.
Resumo:
A recent study showed increased resistance against strongylid nematodes in offspring of a stallion affected by recurrent airway obstruction (RAG) compared with unrelated pasture mates. Resistance against strongylid nematodes was associated with RAG affection. Hypothesis: Resistance against strongylid nematodes has a genetic basis. The genetic variants influencing strongylid resistance also influence RAG susceptibility. Faecal samples from the half-sibling offspring of two RAG-affected Warmblood stallions 98 offspring from the first family (family 1) and 79 from the second family (family 2) were analysed using a combined sedimentation-flotation method. The phenotype was defined as a binary trait - either positive or negative for egg shedding. The influence of non-genetic factors on egg shedding was analysed using SAS, the mode of inheritance was investigated using PAP and iBay, and the association between shedding of strongyle eggs and RAG was estimated by odds ratios. Previously established genotypes for 315 microsatellite markers were used for QTL analyses using GRID QTL. The inheritance of "strongylid egg shedding" is influenced by major genes on ECA15 and ECA20. Shedding of strongylid eggs is associated with RAG in family 1 but not in family 2. Conclusions: The status of "shedding of strongyle eggs" has a genetic background. The results were inconclusive as to whether "egg shedding" and RAG share common genetic components. Our results suggest that it may be possible to select for resistance against strongylid nematodes.
Resumo:
The present study describes the occurrence of intestinal parasite infections in livestock guardian dogs and herding dogs. A total of 71 guardian dogs (more than half of the total number of guardian dogs in Switzerland) and 21 herding dogs were coprologically examined, using a combined sedimentation-flotation method. In 21 (23 %) of the dogs intestinal parasites were detected, and 8 (8.7 %) of these dogs shed either sporocysts of Sarcocystis sp. (n = 6) or taeniid eggs (n = 2). The evaluation of questionnaires providing data on age, origin and deworming schemes of the dogs completed the study.
Increased parasite resistance and recurrent airway obstruction in horses of a high-prevalence family
Resumo:
BACKGROUND: Equine recurrent airway obstruction (RAO) shares many characteristics with human asthma. In humans, an inverse relationship between susceptibility to asthma and resistance to parasites is suspected. HYPOTHESIS/OBJECTIVES: Members of a high-incidence RAO half-sibling family (F) shed fewer strongylid eggs compared with RAO-unaffected pasture mates (PM) and that RAO-affected horses shed fewer eggs than RAO-unaffected half-siblings. ANIMALS: Seventy-three F and 73 unrelated, age matched PM. METHODS: Cases and controls kept under the same management and deworming regime were examined. Each individual was classified as RAO affected or RAO unaffected and fecal samples were collected before and 1-3 weeks and 3 months after deworming. Samples were analyzed by combined sedimentation-flotation and modified McMaster methods and classified into 3 categories of 0 eggs per gram of feces (EpG), 1-100 EpG, and > 100 EpG, respectively. RESULTS: PM compared with RAO-affected F had a 16.7 (95% confidence interval [CI]: 2.0-136.3) times higher risk for shedding > 100 EpG compared with 0 EpG and a 5.3 (95% CI: 1.0-27.4) times higher risk for shedding > 100 EpG compared with 0 EpG. There was no significant effect when RAO-unaffected F were compared with their PM. RAO-unaffected compared with RAO-affected offspring had a 5.8 (95% CI: 0.0-1.0) times higher risk for shedding 1-100 EpG. Age, sex, breed, and sharing pastures with other species had no significant confounding effects. CONCLUSION AND CLINICAL IMPORTANCE: RAO is associated with resistance against strongylid parasites in a high-prevalence family.
Resumo:
Here, we demonstrate the use of a colloidal CdSe:Te quantum dots suspension as active liquid-core in a specially designed optical element, based on a double-clad optical fiber structure. The liquid-core fiber was realized by filling the hollow core of a capillary and waveguiding of the core was ensured by using a liquid host that exhibits a larger refractive index than the cladding material of the capillary. Since the used capillary possessed a cladding waveguide structure, we obtained a liquid-core double-clad structure. To seal the liquid-core fiber and e.g. prevent the formation of bubbles, we developed a technique based on SMA connectors. The colloidal CdSe:Te quantum dots were excited by cladding-pumping using a pump laser at 532nm operating in the continuous-wave regime. We investigated the photoluminescence emitted from the colloidal CdSe:Te quantum dots suspension liquid-core and guided by the double-clad fiber structure. We observed a red shift of the (core) emission, that depends on the liquid-core fiber length and the pump power. This shift is due to the absorption of unexcited colloidal quantum dots and due to the waveguiding properties of the core. Here we report a core photoluminescence output power of 79.2μW (with an integrated brightness of ≈ 215.5 W/cm2sr ). Finally, we give an explanation, why lasing could not be observed in our experiments when setup as a liquid-core fiber cavity.
Resumo:
The protozoan parasite Neospora caninum is one of the most important abortifacient organisms in cattle worldwide. The dog is known to act as definitive host although its potential role as infection source for bovines still remains unelucidated. The aim of the present study was to compile initial epidemiological data on the prevalence and incidence of N. caninum in Swiss dogs acting as definitive hosts. Thus, 249 Swiss dogs were investigated coproscopically in monthly intervals over a period of 1 year. A total of 3289 fecal samples was tested by the flotation technique. Among these, 202 were shown to contain Sarcocystis sp. (6.1%), 149 Cystoisospora sp. (=Isospora sp.; 4.5%) and 25 Hammondia/Neospora-like oocysts (HNlO) (0.7%). All but one sample containing HNlO were from different dogs; one dog shed HNlO at two subsequent time points. Calculation of the yearly incidence for HNlO resulted in the surprisingly high value of 9.2%. Farm dogs exhibited a higher incidence for HNlO than urban family dogs. Thirteen out of the 25 HNlO-samples showed sporulation after 5 days incubation at room temperature. HNlO were further differentiated by species-specific PCR. However, all HNlO-samples were negative for N. caninum, Hammondia heydorni and Toxoplasma gondii. One reason may be the low oocyst density found in most fecal samples, which did not permit us to carry out PCR under optimal conditions. Three out of the 25 HNlO-cases contained enough oocysts to allow further enrichment and purification by the flotation technique. Subsequently, twenty to fifty sporulated HNlO-oocysts were orally administered to Meriones unguiculatus. All gerbils were seronegative for N. caninum at 5 weeks p.i. A N. caninum-seroprevalence of 7.8% was determined by ELISA upon 1132 serum samples collected from dogs randomly selected by veterinarians among their clinical patients.
Resumo:
The end of the Last Glacial Maximum (Termination I), roughly 20 thousand years ago (ka), was marked by cooling in the Northern Hemisphere, a weakening of the Asian monsoon, a rise in atmospheric CO2 concentrations and warming over Antarctica. The sequence of events associated with the previous glacial–interglacial transition (Termination II), roughly 136 ka, is less well constrained. Here we present high-resolution records of atmospheric CO2 concentrations and isotopic composition of N2—an atmospheric temperature proxy—from air bubbles in the EPICA Dome C ice core that span Termination II. We find that atmospheric CO2 concentrations and Antarctic temperature started increasing in phase around 136 ka, but in a second phase of Termination II, from 130.5 to 129 ka, the rise in atmospheric CO2 concentrations lagged that of Antarctic temperature unequivocally. We suggest that during this second phase, the intensification of the low-latitude hydrological cycle resulted in the development of a CO2 sink, which counteracted the CO2 outgassing from the Southern Hemisphere oceans over this period.
Resumo:
When drilling ice cores deeper than ∼100 m, drill liquid is required to maintain ice-core quality and to limit borehole closure. Due to high-pressure air bubbles in the ice, the ice core can crack during drilling and core retrieval, typically at 600–1200 m depth in Greenland. Ice from this 'brittle zone' can be contaminated by drill liquid as it seeps through cracks into the core. Continuous flow analysis (CFA) systems are routinely used to analyse ice for chemical impurities, so the detection of drill liquid is important for validating accurate measurements and avoiding potential instrument damage. An optical detector was constructed to identify drill liquid in CFA tubing by ultraviolet absorption spectroscopy at a wavelength of 290 nm. The set-up was successfully field-tested in the frame of the NEEM ice-core drilling project in Greenland. A total of 27 cases of drill liquid contamination were identified during the analysis of 175 m of brittle zone ice. The analyses most strongly affected by drill liquid contamination include insoluble dust particles, electrolytic conductivity, ammonium, hydrogen peroxide and sulphate. This method may also be applied to other types of drill liquid used at other drill sites.
Resumo:
To provide baseline parasitological data for health surveillance in free-ranging Alpine ibex (Capra ibex ibex), we assessed the endoparasite population and level of parasitism in apparently healthy ibex. Faecal samples from 148 ibex were collected between 2006 and 2008 in two different Swiss ibex colonies. They were analysed by coprology, including combined sedimentation/flotation method, sedimentation method, Baermann funnel technique and Ziehl-Neelsen staining. Gastrointestinal parasites and lungworms were identified in 100% and 81.8% of the examined animals, respectively. Highest prevalences were recorded for gastrointestinal strongylids other than Nematodirus/Marshallagia spp. (100%), Eimeria spp. (100%), Muellerius spp. (79.8%) and Nematodirus/Marshallagia spp. (79.0%). We report for the first time Cryptosporidium sp. in free-ranging Alpine ibex and Cystocaulus spp. in free-ranging ibex from Switzerland. On average, ibex were infected with 3.9 different parasites taxa (range: 1-8). Parasite prevalence and diversity varied significantly between sexes, study sites and seasons. Parasite egg output was low in 95.7% and moderate in 5.3% of the samples. Overall, the results indicate that Alpine ibex are widely infected with endoparasites and suggest that multiple infections are very common in apparently healthy populations. Furthermore, our data underline the potential influence of factors such as sex, study site and season on parasitological findings.
Resumo:
Firn and polar ice cores offer the only direct palaeoatmospheric archive. Analyses of past greenhouse gas concentrations and their isotopic compositions in air bubbles in the ice can help to constrain changes in global biogeochemical cycles in the past. For the analysis of the hydrogen isotopic composition of methane (δD(CH4) or δ2H(CH4)) 0.5 to 1.5 kg of ice was hitherto used. Here we present a method to improve precision and reduce the sample amount for δD(CH4) measurements in (ice core) air. Pre-concentrated methane is focused in front of a high temperature oven (pre-pyrolysis trapping), and molecular hydrogen formed by pyrolysis is trapped afterwards (post-pyrolysis trapping), both on a carbon-PLOT capillary at −196 °C. Argon, oxygen, nitrogen, carbon monoxide, unpyrolysed methane and krypton are trapped together with H2 and must be separated using a second short, cooled chromatographic column to ensure accurate results. Pre- and post-pyrolysis trapping largely removes the isotopic fractionation induced during chromatographic separation and results in a narrow peak in the mass spectrometer. Air standards can be measured with a precision better than 1‰. For polar ice samples from glacial periods, we estimate a precision of 2.3‰ for 350 g of ice (or roughly 30 mL – at standard temperature and pressure (STP) – of air) with 350 ppb of methane. This corresponds to recent tropospheric air samples (about 1900 ppb CH4) of about 6 mL (STP) or about 500 pmol of pure CH4.
Resumo:
This paper investigates empirically the Bolton, Scheinkman, and Xiong (2006) hypothesis, according to which initial shareholders may provide incentives to managers to take actions that stimulate speculative bubbles. We test this hypothesis with data on up to 8,544 directors and up to 1,677 companies between 2004-2008. Using vesting time as a measure of the short-term performance weighting in CEO compensation and various alternative measures of the extent of speculation, the findings support the hypothesis: vesting time decreases with more intensive speculation. The results prove robust in various empirical model specifications.