Temperature effects on export production in the open ocean

A pelagic food web model was formulated with the goal of developing a quantitative understanding of the relationship between total production, export production, and environmental variables in marine ecosystems. The model assumes that primary production is partitioned through both large and small phytoplankton and that the food web adjusts to changes in the rate of allochthonous nutrient inputs in a way that maximizes stability, i.e., the ability of the system to return to steady state following a perturbation. The results of the modeling exercise indicate that ef ratios, defined as new production/total production = export production/total production, are relatively insensitive to total production rates at temperatures greater than ∼25°C and lie in the range 0.1‐0.2. At moderate to high total production rates, ef ratios are insensitive to total production and negatively correlated with temperature. The maximum ef ratios are ∼0.67 at high rates of production and temperatures of 0°−10°C. At temperatures less than ∼20°C, there is a transition from low ef ratios to relatively high ef ratios as total production increases from low to moderate values. This transition accounts for the hyperbolic relationship often presumed to exist between ef ratios and total production. At low rates of production the model predicts a negative correlation between production and ef ratios, a result consistent with data collected at station ALOHA (22°45′N, 158°W) in the North Pacific subtropical gyre. The predictions of the model are in excellent agreement with results reported from the Joint Global Ocean Flux Study (JGOFS) and from other field work. In these studies, there is virtually no correlation between total production and ef ratios, but temperature alone accounts for 86% of the variance in the ef ratios. Model predictions of the absolute and relative abundance of autotrophic and heterotrophic microorganisms are in excellent agreement with data reported from field studies. Combining the ef ratio model with estimates of ocean temperature and photosynthetic rates derived from satellite data indicates that export production on a global scale is ∼20% of net photosynthesis. The results of the model have important implications for the impact of climate change on export production, particularly with respect to temperature effects

A practical approach for applying Bayesian logic to determine the probabilities of subsurface scenarios: example from an offshore oilfield

During appraisal of an undeveloped segment of a producing offshore oilfield, three well penetrations revealed unexpected complexity and compartmentalization. Business decisions on whether and how to develop this segment depended on understanding the possible interpretations of the subsurface. This was achieved using the following steps that incorporated a novel practical application of Bayesian logic. 1. Scenarios were identified to span the full range of possible subsurface interpretations. This was achieved through a facilitated cross-disciplinary exercise including external participants. The exercise generated 12 widely differing subsurface scenarios, which could be grouped into 4 types of mechanisms: slumping, structural, depositional, and diagenetic. 2. Prior probabilities were assigned to each scenario. These probabilities were elicited from the same subsurface team and external experts who performed step 1, using their diverse knowledge and experience. 3. The probabilities of each scenario were updated by evaluating them sequentially with 21 individual pieces of evidence, progressively down-weighting belief in scenarios that were inconsistent with the evidence. For each piece of evidence, the likelihood (chance that the scenario could produce the evidence) was estimated qualitatively by the same team using a “traffic-light” high-medium-low assessment. Offline, these were converted to numerical likelihood values. Posterior probabilities were derived by multiplying the priors by the likelihoods and renormalizing to sum to unity across all of the scenarios. 4. The most probable scenarios were selected for quantitative reservoir modeling, to evaluate the potential outcomes of business decisions, given each scenario. Of the 12 scenarios identified in step 1, most were strongly down-weighted by the sequential revisions against evidence in step 3; after this, only scenarios in the “slumping” group retained significant posterior probabilities. The data showed minimal sensitivity to the initial assumption of prior probability in step 2. This process had several benefits. First, it encouraged the subsurface team to imagine a full range of scenarios that were likely to bracket the actual subsurface “truth,” something that is critical for subsequent decision-making. Second, it allowed belief in the probability of each scenario to be updated systematically in a way that was strongly conditioned to the evidence, so that the choice of scenarios to take through to reservoir modeling was more objective and evidence-based. Third, it allowed an assessment of the usefulness of individual pieces of evidence, which could be used to guide value-of-information assessments for subsequent data acquisition. Finally, the process enabled rigorous Bayesian revision methods to be applied in a simple practical way that engaged the subsurface team without exposing them to the underlying mathematics. During field appraisal and development, when the subsurface is revealed gradually as more data are acquired and studied, the process outlined here provides a practical way of generating and modifying belief in a range of subsurface scenarios while minimizing exposure to potential biases and logical fallacies that could affect subsequent decision quality. It also helps to decide which scenarios are sufficiently probable that they need to be represented by detailed reservoir models

Genetic Deletion of the Clathrin Adaptor GGA3 Reduces Anxiety and Alters GABAergic Transmission

Golgi-localized γ-ear-containing ARF binding protein 3 (GGA3) is a monomeric clathrin adaptor that has been shown to regulate the trafficking of the Beta-site APP-cleaving enzyme (BACE1), which is required for production of the Alzheimer’s disease (AD)-associated amyloid βpeptide. Our previous studies have shown that BACE1 is degraded via the lysosomal pathway and that depletion of GGA3 results in increased BACE1 levels and activity owing to impaired lysosomal trafficking and degradation. We further demonstrated the role of GGA3 in the regulation of BACE1 in vivo by showing that BACE1 levels are increased in the brain of GGA3 null mice. We report here that GGA3 deletion results in novelty-induced hyperactivity and decreased anxiety-like behaviors. Given the pivotal role of GABAergic transmission in the regulation of anxiety-like behaviors, we performed electrophysiological recordings in hippocampal slices and found increased phasic and decreased tonic inhibition in the dentate gyrus granule cells (DGGC). Moreover, we found that the number of inhibitory synapses is increased in the dentate gyrus of GGA3 null mice in further support of the electrophysiological data. Thus, the increased GABAergic transmission is a leading candidate mechanism underlying the reduced anxiety-like behaviors observed in GGA3 null mice. All together these findings suggest that GGA3 plays a key role in GABAergic transmission. Since BACE1 levels are elevated in the brain of GGA3 null mice, it is possible that at least some of these phenotypes are a consequence of increased processing of BACE1 substrates

The central image of a gravitationally lensed quasar

A galaxy can act as a gravitational lens, producing multiple images of a background object. Theory predicts there should be an odd number of images but, paradoxically, almost all observed lenses have 2 or 4 images. The missing image should be faint and appear near the galaxy's center. These ``central images'' have long been sought as probes of galactic cores too distant to resolve with ordinary observations. There are five candidates, but in one case the third image is not necessarily a central image, and in the others, the central component might be a foreground source rather than a lensed image. Here we report the most secure identification of a central image, based on radio observations of PMN J1632-0033, one of the latter candidates. Lens models incorporating the central image show that the mass of the lens galaxy's central black hole is less than 2 x 10^8 M_sun, and the galaxy's surface density at the location of the central image is more than 20,000 M_sun per square parsec, in agreement with expectations based on observations of galaxies hundreds of times closer to the Earth.Comment: Nature, in press [7 pp, 2 figs]. Standard media embargo applies before publicatio

Acquisition of the Sda1-encoding bacteriophage does not enhance virulence of the serotype M1 Streptococcus pyogenes strain SF370

The resurgence of invasive disease caused by Streptococcus pyogenes (group A Streptococcus [GAS]) in the past 30 years has paralleled the emergence and global dissemination of the highly virulent M1T1 clone. The GAS M1T1 clone has diverged from the ancestral M1 serotype by horizontal acquisition of two unique bacteriophages, encoding the potent DNase Sda1/SdaD2 and the superantigen SpeA, respectively. The phage-encoded DNase promotes escape from neutrophil extracellular traps and is linked to enhanced virulence of the M1T1 clone. In this study, we successfully used in vitro lysogenic conversion to transfer the Sda1-encoding phage from the M1T1 clonal strain 5448 to the nonclonal M1 isolate SF370 and determined the impact of this horizontal gene transfer event on virulence. Although Sda1 was expressed in SF370 lysogens, no capacity of the phage-converted strain to survive human neutrophil killing, switch to a hyperinvasive covRS mutant form, or cause invasive lethal infection in a humanized plasminogen mouse model was observed. This work suggests that the hypervirulence of the M1T1 clone is due to the unique synergic effect of the M1T1 clone bacteriophage-specific virulence factor Sda1 acting in concert with the M1T1 clone-specific genetic scaffold

The association of cold weather and all-cause and cause-specific mortality in the island of Ireland between 1984 and 2007

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.This article has been made available through the Brunel Open Access Publishing Fund.Background This study aimed to assess the relationship between cold temperature and daily mortality in the Republic of Ireland (ROI) and Northern Ireland (NI), and to explore any differences in the population responses between the two jurisdictions. Methods A time-stratified case-crossover approach was used to examine this relationship in two adult national populations, between 1984 and 2007. Daily mortality risk was examined in association with exposure to daily maximum temperatures on the same day and up to 6 weeks preceding death, during the winter (December-February) and cold period (October-March), using distributed lag models. Model stratification by age and gender assessed for modification of the cold weather-mortality relationship. Results In the ROI, the impact of cold weather in winter persisted up to 35 days, with a cumulative mortality increase for all-causes of 6.4% (95%CI=4.8%-7.9%) in relation to every 1oC drop in daily maximum temperature, similar increases for cardiovascular disease (CVD) and stroke, and twice as much for respiratory causes. In NI, these associations were less pronounced for CVD causes, and overall extended up to 28 days. Effects of cold weather on mortality increased with age in both jurisdictions, and some suggestive gender differences were observed. Conclusions The study findings indicated strong cold weather-mortality associations in the island of Ireland; these effects were less persistent, and for CVD mortality, smaller in NI than in the ROI. Together with suggestive differences in associations by age and gender between the two Irish jurisdictions, the findings suggest potential contribution of underlying societal differences, and require further exploration. The evidence provided here will hope to contribute to the current efforts to modify fuel policy and reduce winter mortality in Ireland

What Do We Feed to Food-Production Animals? A Review of Animal Feed Ingredients and Their Potential Impacts on Human Health

OBJECTIVE: Animal feeding practices in the United States have changed considerably over the past century. As large-scale, concentrated production methods have become the predominant model for animal husbandry, animal feeds have been modified to include ingredients ranging from rendered animals and animal waste to antibiotics and organoarsenicals. In this article we review current U.S. animal feeding practices and etiologic agents that have been detected in animal feed. Evidence that current feeding practices may lead to adverse human health impacts is also evaluated. DATA SOURCES: We reviewed published veterinary and human-health literature regarding animal feeding practices, etiologic agents present in feed, and human health effects along with proceedings from animal feed workshops. DATA EXTRACTION: Data were extracted from peer-reviewed articles and books identified using PubMed, Agricola, U.S. Department of Agriculture, Food and Drug Administration, and Centers for Disease Control and Prevention databases. DATA SYNTHESIS: Findings emphasize that current animal feeding practices can result in the presence of bacteria, antibiotic-resistant bacteria, prions, arsenicals, and dioxins in feed and animal-based food products. Despite a range of potential human health impacts that could ensue, there are significant data gaps that prevent comprehensive assessments of human health risks associated with animal feed. Limited data are collected at the federal or state level concerning the amounts of specific ingredients used in animal feed, and there are insufficient surveillance systems to monitor etiologic agents “from farm to fork.” CONCLUSIONS: Increased funding for integrated veterinary and human health surveillance systems and increased collaboration among feed professionals, animal producers, and veterinary and public health officials is necessary to effectively address these issues

Induction of humoral immune response to multiple recombinant Rhipicephalus appendiculatus antigens and their effect on tick feeding success and pathogen transmission

BACKGROUND: Rhipicephalus appendiculatus is the primary vector of Theileria parva, the etiological agent of East Coast fever (ECF), a devastating disease of cattle in sub-Saharan Africa. We hypothesized that a vaccine targeting tick proteins that are involved in attachment and feeding might affect feeding success and possibly reduce tick-borne transmission of T. parva. Here we report the evaluation of a multivalent vaccine cocktail of tick antigens for their ability to reduce R. appendiculatus feeding success and possibly reduce tick-transmission of T. parva in a natural host-tick-parasite challenge model. METHODS: Cattle were inoculated with a multivalent antigen cocktail containing recombinant tick protective antigen subolesin as well as two additional R. appendiculatus saliva antigens: the cement protein TRP64, and three different histamine binding proteins. The cocktail also contained the T. parva sporozoite antigen p67C. The effect of vaccination on the feeding success of nymphal and adult R. appendiculatus ticks was evaluated together with the effect on transmission of T. parva using a tick challenge model. RESULTS: To our knowledge, this is the first evaluation of the anti-tick effects of these antigens in the natural host-tick-parasite combination. In spite of evidence of strong immune responses to all of the antigens in the cocktail, vaccination with this combination of tick and parasite antigens did not appear to effect tick feeding success or reduce transmission of T. parva. CONCLUSION: The results of this study highlight the importance of early evaluation of anti-tick vaccine candidates in biologically relevant challenge systems using the natural tick-host-parasite combination