Stable Isotopic Variability within Modern Travertines

Six hot and two ambient water travertine systems were sampled to determine the relationships between the stable isotopic composition of the travertines and the waters from which they were deposited. This was conducted in order to evaluate the use of geochemical analyses of ancient travertines for the interpretation of the composition of the waters from which they precipitated, climatic conditions at time of formation, etc. The waters displayed down-flow trends of progressively higher (^ 8'3C values, in all 8 systems, and (H) 618O values, in all 6 hot water systems. Whereas the stable isotopic values of the mineral precipitates sometimes showed similar trends, the magnitude of the downflow changes commonly was quite different than that exhibited by the water data. Additionally, different types of precipitates, which formed within centimeters of each other, commonly had different stable isotopic compositions, e.g., crusts which formed at the air/water interface always had higher 813C and 8'8O values than constituents which formed within the immediately subjacent water column. The lack of a simple relationship between stable isotopic composition of the water and the precipitate is due to the fact that the stable isotopic composition of the precipitates are controlled by a number of variables, including the water's composition, temperature, level of saturation, etc. And these variables can change dramatically within very short distances and at the same spot within very short time intervals. Thus, as demonstrated by the stable isotope data, attempting to interpret the composition of the water from the composition of the deposit is a highly risky venture.Six ensembles travertineux de sources chaudes et deux ensembles à température ambiante ont été échantillonnés afin de déterminer les liens entre la teneur en isotopes stables des travertins et celle des eaux dans lesquels ils ont été déposés. Cette analyse a été faite dans le but d'évaluer l'utilité des analyses géochimiques d'anciens travertins pour déterminer la composition des eaux où a eu lieu la précipitation, les conditions climatiques lors de leur formation, etc. Les eaux ont montré une augmentation vers l'aval des valeurs de 8'3C dans les huit ensembles et de celles de 818O dans les six ensembles " chauds ". Là où les valeurs des isotopes stables des précipités minéraux montraient parfois des tendances similaires, l'ampleur des changements vers l'aval était habituellement fort différente de celle qu'indiquent les données sur les eaux. De plus, les différents types de précipités, situés à des distances centimétriques les uns des autres, avaient souvent des teneurs isotopiques différentes; ainsi les croûtes formées à l'interface de l'eau et de l'air avaient toujours des valeurs plus élevées de 8'3C et de 8'8O que les constituants formés à l'intérieur de la colonne d'eau sousjacente. L'absence d'une relation simple entre la teneur isotopique de l'eau et du précipité est attribuable au fait que la teneur isotopique des précipités est déterminée par un certains nombre de variables, notamment la composition de l'eau, la température, le niveau de saturation, etc. Ces variables peuvent être fort différentes sur de très courtes distances ou au même endroit sur un court laps de temps. Ainsi, comme le démontrent les données sur les isotopes stables, il est fort risqué de vouloir interpréter la composition de l'eau à partir de celle du dépôt.Sechs Travertin-Systemen mit heiBem Wasser und zwei mit der Umgebung angepaBter Wasserwarme wurden Stich-proben entnommen, um die Beziehungen zwischen der stabilen isotopischen Zusammensetzung der Travertine und den Quellen, durch die sie abgesetzt wurden, zu bestim-men. Dièse Analyse wurde mit dem Ziel durchgefùhrt, den Nutzen geochemischer Analysen von alten Travertinen bei der Interpretation der Zusammensetzung der Quellen, aus denen sie ausgeschieden wurden, der klimatischen Bedingungen zur Zeit ihrer Bildung u.s.w. zu beurteilen. Die Wasser zeigten talwârts Trends von zunehmend hôheren 8'3C-Werten in alien 8 Systemen und 8'80-Werte in alien 6 HeiBwasser-Systemen. Wàhrend die stabilen isotopischen Werte der Mineral-Ausscheidungen manchmal âhnliche Trends zeigten, war der Umfang der Verànderungen talwârts im allgemeinen sehr verschieden von denen, die in den Wasser-Daten angezeigt wurden. AuBerdem hatten verschiedene Arien von Ausscheidungen, welche sich in Zentimeter-Entfernung voneinander bildeten, gewôhnlich unterschiedliche stabile isotopische Zusammensetzungen, d.h. Krusten, die sich an der Schnittstelle Luft/ Wasser bildeten, hatten immer hôhere 8'3C-und 8'80-Werte als Bestandteile, welche sich innerhalb der direkt darunterliegenden Wasser-Sâule bildeten. Das Fehlen einer einfachen Beziehung zwischen stabiler isotopischer Zusammensetzung des Wassers und der Ausscheidung beruht auf der Tatsache, daB die stabile isotopische Zusammensetzung der Ausscheidungen durch eine Reihe von Variablen kontrolliert werden wie Zusammensetzung des Wassers, Temperatur, Saturations-niveau u.s.w. Und dièse Variablen kônnen sich dramatisch veràndern innerhalb sehr geringer Entfernungen und an derselben Stelle innerhalb sehr kurzer Zeitrâume. Wie die stabilen isotopischen Daten zeigen, ist also der Versuch, die Wasserzusammensetzung von der Zusammensetzung der Ablagerung aus zu interpretieren ein, hoch riskantes Untemehmen

Ecological succession of a Jurassic shallow-water ichthyosaur fall.

After the discovery of whale fall communities in modern oceans, it has been hypothesized that during the Mesozoic the carcasses of marine reptiles created similar habitats supporting long-lived and specialized animal communities. Here, we report a fully documented ichthyosaur fall community, from a Late Jurassic shelf setting, and reconstruct the ecological succession of its micro- and macrofauna. The early 'mobile-scavenger' and 'enrichment-opportunist' stages were not succeeded by a 'sulphophilic stage' characterized by chemosynthetic molluscs, but instead the bones were colonized by microbial mats that attracted echinoids and other mat-grazing invertebrates. Abundant cemented suspension feeders indicate a well-developed 'reef stage' with prolonged exposure and colonization of the bones prior to final burial, unlike in modern whale falls where organisms such as the ubiquitous bone-eating worm Osedax rapidly destroy the skeleton. Shallow-water ichthyosaur falls thus fulfilled similar ecological roles to shallow whale falls, and did not support specialized chemosynthetic communities

Exercise therapy in adults with serious mental illness: a systematic review and meta-analysis

Background: Individuals with serious mental illness are at a higher risk of physical ill health. Mortality rates are at least twice those of the general population with higher levels of cardiovascular disease, metabolic disease, diabetes, and respiratory illness. Although genetics may have a role in the physical health problems of these patients, lifestyle and environmental factors such as levels of smoking, obesity, poor diet, and low levels of physical activity also play a prominent part.<p></p> Objective: To conduct a systematic review and meta-analysis of randomised controlled trials comparing the effect of exercise interventions on individuals with serious mental illness.<p></p> Methods: Searches were made in Ovid MEDLINE, Embase, CINAHL, PsycINFO, Biological Abstracts on Ovid, and The Cochrane Library (January 2009, repeated January 2013) through to February 2013.<p></p> Results: Eight RCTs were identified in the systematic search. Six compared exercise versus usual care. One study assessed the effect of a cycling programme versus muscle strengthening and toning exercises. The final study compared the effect of adding specific exercise advice and motivational skills to a simple walking programme. Exercise programmes were noted by their heterogeneity in terms of the type of exercise intervention, setting, and outcome measures. The review found that exercise improved levels of exercise activity (n=13, standard mean difference [SMD] 1.81, CI 0.44 to 3.18, p = 0.01). No beneficial effect was found on negative (n = 84, SMD = -0.54, CI -1.79 to 0.71, p = 0.40) or positive symptoms of schizophrenia (n = 84, SMD = -1.66, CI -3.78 to 0.45, p = 0.12). No change was found on body mass index compared with usual care (n= 151, SMD = -0.24, CI -0.56 to 0.08, p = 0.14), or body weight (n = 77, SMD = 0.13, CI -0.32 to 0.58, p = 0.57). No beneficial effect was found on anxiety and depressive symptoms (n = 94, SMD = -0.26, CI -0.91 to 0.39, p = 0.43), or quality of life in respect of physical and mental domains. One RCT measured the effect of exercise on exercise intensity, attendance, and persistence at a programme. No significant effect was found on these measures.<p></p> Conclusions: This systematic review showed that exercise therapies can lead to a modest increase in levels of exercise activity but overall there was no noticeable change for symptoms of mental health, body mass index, and body weight.<p></p&gt

Missing Links: Referrer Behavior and Job Segregation

How does referral recruitment contribute to job segregation, and what can organizations do about it? Current theory on network effects in the labor market emphasizes the job-seeker perspective, focusing on the segregated nature of job-seekers’ information and contact networks, and leaves little role for organizational influence. But employee referrals are necessarily initiated from within a firm by referrers. We argue that referrer behavior is the missing link that can help organizations manage the segregating effects of referring. Adopting the referrer’s perspective of the process, we develop a computational model which integrates a set of empirically documented referrer behavior mechanisms gleaned from extant organizational case studies. Using this model, we compare the segregating effects of referring when these behaviors are inactive to the effects when the behaviors are active. We show that referrer behaviors substantially boost the segregating effects of referring. This impact of referrer behavior presents an opportunity for organizations. Contrary to popular wisdom, we show that organizational policies designed to influence referrer behaviors can mitigate most if not all of the segregating effects of referring

Packages of Care for Schizophrenia in Low- and Middle-Income Countries

In the third in a series of six articles on packages of care for mental disorders in low- and middle-income countries, Jair Mari and colleagues discuss the treatment of schizophrenia

Light-Dependant Biostabilisation of Sediments by Stromatolite Assemblages

For the first time we have investigated the natural ecosystem engineering capacity of stromatolitic microbial assemblages. Stromatolites are laminated sedimentary structures formed by microbial activity and are considered to have dominated the shallows of the Precambrian oceans. Their fossilised remains are the most ancient unambiguous record of early life on earth. Stromatolites can therefore be considered as the first recognisable ecosystems on the planet. However, while many discussions have taken place over their structure and form, we have very little information on their functional ecology and how such assemblages persisted despite strong eternal forcing from wind and waves. The capture and binding of sediment is clearly a critical feature for the formation and persistence of stromatolite assemblages. Here, we investigated the ecosystem engineering capacity of stromatolitic microbial assemblages with respect to their ability to stabilise sediment using material from one of the few remaining living stromatolite systems (Highborne Cay, Bahamas). It was shown that the most effective assemblages could produce a rapid (12–24 h) and significant increase in sediment stability that continued in a linear fashion over the period of the experimentation (228 h). Importantly, it was also found that light was required for the assemblages to produce this stabilisation effect and that removal of assemblage into darkness could lead to a partial reversal of the stabilisation. This was attributed to the breakdown of extracellular polymeric substances under anaerobic conditions. These data were supported by microelectrode profiling of oxygen and calcium. The structure of the assemblages as they formed was visualised by low-temperature scanning electron microscopy and confocal laser microscopy. These results have implications for the understanding of early stromatolite development and highlight the potential importance of the evolution of photosynthesis in the mat forming process. The evolution of photosynthesis may have provided an important advance for the niche construction activity of microbial systems and the formation and persistence of the stromatolites which came to dominate shallow coastal environments for 80% of the biotic history of the earth

PP13, Maternal ABO Blood Groups and the Risk Assessment of Pregnancy Complications

Placental Protein 13 (PP13), an early biomarker of preeclampsia, is a placenta-specific galectin that binds beta-galactosides, building-blocks of ABO blood-group antigens, possibly affecting its bioavailability in blood.We studied PP13-binding to erythrocytes, maternal blood-group effect on serum PP13 and its performance as a predictor of preeclampsia and intrauterine growth restriction (IUGR). Datasets of maternal serum PP13 in Caucasian (n = 1078) and Hispanic (n = 242) women were analyzed according to blood groups. In vivo, in vitro and in silico PP13-binding to ABO blood-group antigens and erythrocytes were studied by PP13-immunostainings of placental tissue-microarrays, flow-cytometry of erythrocyte-bound PP13, and model-building of PP13--blood-group H antigen complex, respectively. Women with blood group AB had the lowest serum PP13 in the first trimester, while those with blood group B had the highest PP13 throughout pregnancy. In accordance, PP13-binding was the strongest to blood-group AB erythrocytes and weakest to blood-group B erythrocytes. PP13-staining of maternal and fetal erythrocytes was revealed, and a plausible molecular model of PP13 complexed with blood-group H antigen was built. Adjustment of PP13 MoMs to maternal ABO blood group improved the prediction accuracy of first trimester maternal serum PP13 MoMs for preeclampsia and IUGR.ABO blood group can alter PP13-bioavailability in blood, and it may also be a key determinant for other lectins' bioavailability in the circulation. The adjustment of PP13 MoMs to ABO blood group improves the predictive accuracy of this test