Brain Death: An Investigation of Current Controversies

Brain death is a highly debated and controversial topic spanning across several bodies of knowledge. Controversies of brain death include, but are not limited to, lack of consensus, false-positive diagnoses, residual function, public perception, and rights. Though brain death is often sensationalized by the media, distrust by the general population is warranted. The lack of consensus amongst professionals regarding brain death suggest that the American Academy of Neurology’s criterion must be revised. At the minimum, revising of the AAN criterion should focus on evolving ancillary testing, and establishing a minimum observation time before declaring death. Upon further clarification of discrepancies, trust will be restored in the medical community regarding end of life decisions

Modeling the potential effects of \u3ci\u3ePlasmodium\u3c/i\u3e infection on the Galapagos penguin (\u3ci\u3eSpheniscus mendiculus\u3c/i\u3e)

The recently discovered presence of a species of Plasmodium infecting the endangered Galapagos penguin (Spheniscus mendiculus) potentially threatens their long-term persistence. However, not much information is available on the transmission dynamics of Plasmodium in Galapagos or the impact of the parasite on infected penguins. The present work takes the model of the Galapagos penguin population devised by Vargas et al. (2007)—which did not include any impacts from disease—and adds a simple model of infection. Two variables—the probability of an individual becoming infected each year, and the increase in annual mortality caused by infection—define the dynamics of the disease component of the model; the stress from El Niño events could also affect infected individuals in different ways, and so three forms of stress-induced relapse are explored as well. The entirety of parameter space is explored for all three relapse scenarios. All the models show a high impact due to mortality from infection, and there are large parts of parameter space that have a 0% probability of persistence over the next 100 years. The probability of persistence decreases substantially if relapse events occur during all El Niño events, weak and strong. Increasing the breeding success of the population provides a modest benefit, but does not reverse the overall trend. In order to estimate the mortality that might be associated with Plasmodium infection, a comparison was made between census data from 1998–2009 and model predictions based on these same years. The models differed in their level of mortality from infection, and a range of plausible parameter values was determined from the best-fitting models; these ranged from 0–10% to 0–15%, depending on the type of relapse modeled. Even at these relatively low levels of impact, Plasmodium infection still has the potential to drastically reduce the probability of persistence of the penguin population over the next 100 years

Constraints on mechanisms and rates of anaerobic oxidation of methane by microbial consortia: process-based modeling of ANME-2 archaea and sulfate reducing bacteria interactions

Anaerobic oxidation of methane (AOM) is the main process responsible for the removal of methane generated in Earth's marine subsurface environments. However, the biochemical mechanism of AOM remains elusive. By explicitly resolving the observed spatial arrangement of methanotrophic archaea and sulfate reducing bacteria found in consortia mediating AOM, potential intermediates involved in the electron transfer between the methane oxidizing and sulfate reducing partners were investigated via a consortium-scale reaction transport model that integrates the effect of diffusional transport with thermodynamic and kinetic controls on microbial activity. Model simulations were used to assess the impact of poorly constrained microbial characteristics such as minimum energy requirements to sustain metabolism and cell specific rates. The role of environmental conditions such as the influence of methane levels on the feasibility of H<sub>2</sub>, formate and acetate as intermediate species, and the impact of the abundance of intermediate species on pathway reversal were examined. The results show that higher production rates of intermediates via AOM lead to increased diffusive fluxes from the methane oxidizing archaea to sulfate reducing bacteria, but the build-up of the exchangeable species can cause the energy yield of AOM to drop below that required for ATP production. Comparison to data from laboratory experiments shows that under the experimental conditions of Nauhaus et al. (2007), none of the potential intermediates considered here is able to support metabolic activity matching the measured rates

Natürliche Konservierung fürs Joghurt

Dieser Artikel wurde mit freundlicher Genehmigung des Verlags zweitveröffentlicht

Natürliche Konservierung fürs Joghurt

Dieser Artikel wurde mit freundlicher Genehmigung des Verlags zweitveröffentlicht

A novel multiplex PCR/RFLP assay for the identification of Streptococcus bovis/Streptococcus equinus complex members from dairy microbial communities based on the 16S rRNA gene

The Streptococcus bovis/Streptococcus equinus complex (SBSEC) comprises pathogenic species associated with different degrees with human infections but also spontaneously fermented dairy products. We aimed therefore at developing a specific identification assay for the SBSEC targeting the 16S rRNA gene comprising a multiplex PCR followed by a differentiating restriction fragment length polymorphisms (RFLP). The multiplex PCR assay was positively applied on 200 SBSEC isolates including reference strains. The assay did not yield false-positive amplifications with strains of closely related bacteria and isolates of non-SBSEC streptococci, lactococci, enterococci, and other genera of dairy origin. The downstream RFLP using MseI and XbaI enabled further discrimination of Streptococcus infantarius/S. bovis (biotype II.1) from Streptococcus gallolyticus (biotype I and II.2)/Streptococcus alactolyticus and S. equinus. Furthermore, the newly developed primers can be used directly for Sanger sequencing. Conclusively, this novel PCR/RFLP assay is applicable in the complex dairy microbial communities and provides an important tool to assess the prevalence of members of the SBSEC in dairy product

Engineered reporter phages for detection of Escherichia coli, Enterococcus, and Klebsiella in urine

The rapid detection and species-level differentiation of bacterial pathogens facilitates antibiotic stewardship and improves disease management. Here, we develop a rapid bacteriophage-based diagnostic assay to detect the most prevalent pathogens causing urinary tract infections: Escherichia coli, Enterococcus spp., and Klebsiella spp. For each uropathogen, two virulent phages were genetically engineered to express a nanoluciferase reporter gene upon host infection. Using 206 patient urine samples, reporter phage-induced bioluminescence was quantified to identify bacteriuria and the assay was benchmarked against conventional urinalysis. Overall, E. coli, Enterococcus spp., and Klebsiella spp. were each detected with high sensitivity (68%, 78%, 87%), specificity (99%, 99%, 99%), and accuracy (90%, 94%, 98%) at a resolution of ≥1

Propagation of surge waves in channels with large-scale bank roughness

In open channels, a sudden rise in water elevation generates a positive surge. Positive surges are commonly observed in man-made channels (Bazin 1865, Treske 1994) and a natural occurrence is the tidal bore in macro-tidal estuaries (Tricker 1965, Chanson 2011a). The positive surge may propagate upstream or downstream (Fig. D1). It is a rapidly-varied flow and the flow properties immediately upstream and downstream of the front must satisfy the continuity and momentum principles (Rouse 1938, Liggett 1994). The authors investigated positive surge waves in a long channel with a range of sidewall configuration. Their configuration corresponded to a downstream surge configuration (Fig. D1, right). The contribution is a welcome addition to the literature on rapidly-varied unsteady open channel flows. In this discussion, it is shown that the effects of boundary friction were previously documented, and a recent investigation provided some insight into the energy dissipation induced by large-scale sidewall roughness

Hydropeaking indicators for characterization of the Upper-Rhone River in Switzerland

River channelization and the construction of high-head storage schemes have been the basis of agricultural and socio-economic development in many alpine regions. One example is the Upper-Rhone River in Switzerland. The Upper-Rhone's morphology changed considerably between 1863 and 1960 as a result of two major channelizations and, from 1950 on, the construction of a large number of high-head storage hydropower schemes in the catchment. These modifications have brought large benefits to the local population, at the cost, however, of substantial disturbances in aquatic and terrestrial ecosystems in and along the river. A primary factor behind these disturbances is the alteration of the natural flow regime, namely hydropeaking due to the operation of the high-head storage hydropower plants. For sustainable river-restoration projects on regulated rivers, scientists and engineers now widely accept the necessity of integrated management of the river. Different aspects such as river morphology, sediment management, water quality, temperature, and the naturally variable flow regime should be considered simultaneously. Mitigation of non-natural, sub-daily flow fluctuations due to hydropeaking is a crucial step in restoring natural flow regimes, but is especially challenging due to the economic constraints such mitigation places upon hydropower plants. With the goal of addressing this challenge, this paper proposes three indicators to describe the flow regime of rivers in alpine catchments with and without high-head storage hydropower plants. The indicators quantify: (1) the seasonal distribution and transfer of water, (2) sub-daily flow fluctuations, and (3) the intensity and frequency of flow changes. Indicators are evaluated in a case study of the Upper-Rhone River for pre- and post-impact situations, and the benefit of a multipurpose project reducing hydropeaking on hydrologic conditions is quantified. Furthermore, the paper explores the possibility of using these indicators to link aquatic and terrestrial ecosystem well being to their hydrolog