Influence of Mechanical and Thermal Boundary Conditions on Stabilizing/Destabilizing Mechanisms in Evaporating Liquid Films

Liquid films, evaporating or non-evaporating, are ubiquitous in nature and technology. The dynamics of evaporating liquid films is a study applicable in several industries such as water recovery, heat exchangers, crystal growth, drug design etc. The theory describing the dynamics of liquid films crosses several fields such as engineering, mathematics, material science, biophysics and volcanology to name a few. Interfacial instabilities typically manifest by the undulation of an interface from a presumed flat state or by the onset of a secondary flow state from a primary quiescent state or both. To study the instabilities affecting liquid films, an evaporating/non-evaporating Newtonian liquid film is subject to a perturbation. Numerical analysis is conducted on configurations of such liquid films being heated on solid surfaces in order to examine the various stabilizing and destabilizing mechanisms that can cause the formation of different convective structures. These convective structures have implications towards heat transfer that occurs via this process. Certain aspects of this research topic have not received attention, as will be obvious from the literature review. Static, horizontal liquid films on solid surfaces are examined for their resistance to long wave type instabilities via linear stability analysis, method of normal modes and finite difference methods. The spatiotemporal evolution equation, available in literature, describing the time evolution of a liquid film heated on a solid surface, is utilized to analyze various stabilizing/destabilizing mechanisms affecting evaporating and non-evaporating liquid films. The impact of these mechanisms on the film stability and structure for both buoyant and non-buoyant films will be examined by the variation of mechanical and thermal boundary conditions. Films evaporating in zero gravity are studied using the evolution equation. It is found that films that are stable to long wave type instabilities in terrestrial gravity are prone to destabilization via long wave instabilities in zero gravity.

The Determination of Aluminum in the Presence of Manganese and Iron by the Use of a Mercury Cathode

Since 1880, when Wolcott Gibbs made the suggestion that mercury could be used as a cathode in gravimetric electroanalysis, many articles have appeared in literature either criticizing the method or citing successful results which have been obtained by it.

An Isopach Map and a Discussion of the Permian in Wyoming and Adjacent Areas

The accelerated post-war demand for petroleum products with resultant high prices and dwindling reserves has spurred producers to an extensive search for new fields and for ad­ditional production in known fields. Exploration and discov­ery is dependent on the collection and correlation of vast amounts of data both in the field and that found in liter­ature.

Coronary bypass surgery in patients treated with clopidogrel. Is it safe?

PURPOSE OF REVIEW: Current guidelines for the management of acute coronary syndrome clearly recommend that clopidogrel should be started before diagnostic coronary angiography. If patients undergo coronary artery bypass grafting (CABG) early after clopidogrel loading or during continued exposure, it seems reasonable to expect an increase in bleeding complications. RECENT FINDINGS: Earlier studies may have overestimated the risk of bleeding in patient undergoing CABG with prior clopidogrel exposure (5-10-fold increase). Some conflicting results are reported in literature. As reexploration because of excessive bleeding is concerned, a two to three-fold increase must be expected, which is demonstrated in actual trials properly matched to confounding factors. Discontinuation of clopidogrel for 5-7 days prior to urgent CABG as recommended by guidelines is not well adopted in clinical practice for several reasons. SUMMARY: There is a moderately elevated risk of bleeding complications after CABG due to prior clopidogrel exposure alone. However, in clinical practice this risk is added often to patients who carry already elevated surgical risks (urgent procedures, worse coronary anatomy, history of previous myocardial infarction and prior percutaneous intervention), and after bleeding complications singular patients may suffer from consecutive adverse outcome. Cessation of clopidogrel in patients before CABG clearly prolongs hospitalization time and has an estimated 1% risk of coronary events during the waiting period. Risk and benefit have to be balanced in every individual case.

Epidemiologic survey in Swiss group-housed breeding rabbits: extent of lesions and potential risk factors

In Switzerland, group-housing for breeding rabbit does is not explicitly required by law, but label programmes, as well as the general public and animal welfare groups, are advocating it. Although group-housing is of great benefit to the gregariously living rabbits, the establishment of a social hierarchy within the group might lead to stress and lesions. In the present epidemiological study, lesions were scored twice on 30% of the breeding does on all 28 commercial Swiss farms with group-housed breeding does. Additionally, a detailed questionnaire was filled out with all producers to determine risk factors potentially associated with lesions. Data were analysed using hierarchical proportional odds models. About 33% of the does examined had lesions, including wounds that were almost healed and small scratches. Severe lesions were counted on 9% of the animals. Differences between seasons in lesions score were identified, with the extent of lesions being higher in summer than in spring. Fewer lesions occurred on farms on which mastitis was more common. More lesions were found on farms where the does were isolated between littering and artificial insemination than on farms without isolation. According to the producers, most of the aggression occurred directly after the isolation phase when the does were regrouped again. We conclude that lesions in group-housed breeding does might be reduced by appropriate reproductive management.

Sudden death in a case of sickle cell anemia: post-mortem computed tomography and autopsy correlation from a radiologist's perspective

Sickle cell anemia (SCA) is a hemolytic disease characterized by the production of abnormal hemoglobin chains and distorted red blood cell morphology or sickling. "Sickle cell crisis" includes vaso-occlusive crisis, a plastic crisis, sequestration crisis, haemolytic crisis and often culminating in serious complications, organ damage and even sudden death. Post-mortem computed tomography (PMCT) findings of sickle cell disease have never been reported in literature. This case of sudden death from acute hemolytic crisis in SCA where post-mortem computed tomography (PMCT) and autopsy findings complemented each other, both revealing findings invisible to the other and both crucial to the case.

Psychological adaptation to spousal loss in old age: The role of personality

Spousal loss is an inevitable critical life event for most individuals in old age, mostly associated with a negative impact on various well-being measures, ie. lower life satisfaction, higher rates of loneliness and depressive symptoms compared to married peers. While the negative effects on well-being are well documented in literature, the modifying factors accounting for the large variability in adaptation to loss are discussed controversially. The potential relevance of personality in the adaptation process has rarely been examined and findings regarding the role of time since loss are contradictory. Based on a vulnerability-stress-model this contribution aims a) to compare psychological well-being of bereaved individuals with married counterparts and b) to investigate the protective effects of different personality traits (Big Five, resilience), and the role of time since loss for adaptation in terms of life satisfaction, loneliness and depression. Data from a questionnaire study about the loss of a spouse in middle and old age in the German- and French-speaking parts of Switzerland are reported. The study is part of the Swiss National Centre of Competence in Research LIVES (Swiss National Science Foundation). The sample consists of 351 widowed persons (39% men, widowed since 0 - 5 years), and 605 married controls (50% men), aged 60 - 89 years. Group comparisons reveal the detrimental effect of spousal bereavement on all indicators of psychological adaptation. Results from hierarchical regression analyses show furthermore, that the effect of spousal loss on all psychological outcomes is moderated by personality traits. Separate analyses with the group of bereaved individuals suggest, that the protective effect of personality varies by the time passed since loss. Our results contribute to a better understanding of the variability in psychological adaptation to spousal loss in old age and give hints for counselling practice.

Seasonal Variation in the Capacity for Plant Trait Measures to Predict Grassland Carbon and Water Fluxes

There is a need for accurate predictions of ecosystem carbon (C) and water fluxes in field conditions. Previous research has shown that ecosystem properties can be predicted from community abundance-weighted means (CWM) of plant functional traits and measures of trait variability within a community (FDvar). The capacity for traits to predict carbon (C) and water fluxes, and the seasonal dependency of these trait-function relationships has not been fully explored. Here we measured daytime C and water fluxes over four seasons in grasslands of a range of successional ages in southern England. In a model selection procedure, we related these fluxes to environmental covariates and plant biomass measures before adding CWM and FDvar plant trait measures that were scaled up from measures of individual plants grown in greenhouse conditions. Models describing fluxes in periods of low biological activity contained few predictors, which were usually abiotic factors. In more biologically active periods, models contained more predictors, including plant trait measures. Field-based plant biomass measures were generally better predictors of fluxes than CWM and FDvar traits. However, when these measures were used in combination traits accounted for additional variation. Where traits were significant predictors their identity often reflected seasonal vegetation dynamics. These results suggest that database derived trait measures can improve the prediction of ecosystem C and water fluxes. Controlled studies and those involving more detailed flux measurements are required to validate and explore these findings, a worthwhile effort given the potential for using simple vegetation measures to help predict landscape-scale fluxes.

Does fog chemistry in Switzerland change with altitude?

During two extended summer seasons in 2006 and 2007 we operated two battery driven versions of the Caltech active strand cloud water collector (MiniCASCC) at the Niesen mountain (2362 m a.s.l.) in the northern part of the Swiss Alps, and two devices at the Lägeren research tower (690 m a.s.l.) at the northern boundary of the Swiss Plateau. During these two field operation phases we gained weekly samples of fog water, where we analyzed the major anions and cations, and the isotope ratios of fog water (in form of δ2H and δ18O). Dominant ions in fog water at all sites were NH4+, NO3−, and SO42 −. Compared to precipitation, the enrichment factors in fog water were in the range 5–9 at the highest site, Niesen Kulm. We found considerably lower summertime ion loadings in fog water at the two Alpine sites than at lower elevations above the Swiss Plateau. The lowest ion concentrations were found at the Niesen Kulm site at 2300 m a.s.l., whereas the highest concentrations (a factor 7 compared to Niesen Kulm) were found in fog water at the Lägeren site. Occult nitrogen deposition was estimated from fog frequency and typical fog water flux rates. This pathway contributes 0.3–3.9 kg N ha− 1 yr− 1 to the total N deposition at the highest site on Niesen mountain, and 0.1–2.2 kg N ha− 1 yr− 1 at the lower site. These inputs are the reverse of ion concentrations measured in fog due to the 2.5 times higher frequency of fog occurrence at the mountain top (overall fog occurrence was 25% of the time) as compared to the lower Niesen Schwandegg site. Although fog water concentrations were on the lower range reported in earlier studies, fog water is likely to be an important N source for Northern Alpine ecosystems and might reach values up to 16% of the total N deposition and up to 75% of wet N deposition by precipitation.

Does Age Matter? Semantic Memory in Healthy Young and Elderly Adults

Background: Semantic memory processes have been well described in literature. However, the available findings are mostly based on relatively young subjects and concrete word material (e.g. tree). Comparatively little information exists about semantic memory for abstract words (e.g. mind) and possible age related changes in semantic retrieval. In this respect, we developed a paradigm that is useful to investigate the implicit (i.e. attentionindependent) access to concrete and abstract semantic memory. These processes were then compared between young and elderly healthy subjects. Methods: A well established tool for investigating semantic memory processes is the semantic priming paradigm, which consists both of semantically unrelated and related word pairs. In our behavioral task these noun-noun word pairs were further divided into concrete, abstract and matched pronounceable non-word conditions. With this premise, the young and elderly participants performed a lexical decision task: they were asked to press a choice of two buttons as an indication for whether the word pair contained a non-word or not. In order to minimize controlled (i.e. attention-dependent) retrieval strategies, a short stimulus onset asynchrony (SOA) of 150ms was set. Reaction time (RT) changes and accuracy to related and unrelated words (priming effect) in the abstract vs. concrete condition (concreteness effect) were the dependent variables of interest. Results and Discussion: Statistical analysis confirmed both a significant priming effect (i.e. shorter RTs in semantically related compared to unrelated words) and a concreteness effect (i.e. RT decrease for concrete compared to abstract words) in the young and elderly subjects. There was no age difference in accuracy. The only age effect was a commonly known general slowing in RT over all conditions. In conclusion, age is not a critical factor in the implicit access to abstract and concrete semantic memory.

The stable carbon isotopic composition of Daphnia ephippia in small, temperate lakes reflects in-lake methane availability

Daphnia can ingest methane-oxidizing bacteria and incorporate methanogenic carbon into their biomass, leading to low stable carbon isotope ratios (expressed as δ13C values) of their tissue. Therefore, δ13C analysis of Daphnia resting eggs (ephippia) in lake sediment records can potentially be used to reconstruct past in-lake availability of methane (CH4). However, detailed multilake studies demonstrating that δ13C values of recently deposited Daphnia ephippia (δ13Cephippia) are systematically related to in-lake CH4 concentrations (CH4aq) are still missing. We measured δ13Cephippia from surface sediments of 15 small lakes in Europe, and compared these values with late-summer CH4aq. δ13Cephippia ranged from −51.6‰ to −25.9‰, and was strongly correlated with CH4aq in the surface water and above the sediment (r −0.73 and −0.77, respectively), whereas a negative rather than the expected positive correlation was found with δ13C values of carbon dioxide (CO2) (r −0.54), and no correlation was observed with CO2aq. At eight sites, offsets between δ13 CCO2 and δ13Cephippia exceeded offsets between δ13 CCO2 and δ13Calgae reported in literature. δ13Cephippia was positively correlated with δ13C values of sedimentary organic matter (r 0.54), but up to 20.7‰ lower in all except one of the lakes (average −6.1‰). We conclude that incorporation of methanogenic carbon prior to ephippia formation must have been widespread by Daphnia in our study lakes, especially those with high CH4aq. Our results suggest a systematic relationship between δ13Cephippia values and CH4aq in small temperate lakes, and that δ13Cephippia analysis on sediment records may provide insights into past changes in in-lake CH4aq.