Spatial and temporal patterns of the zooplankton in the Westerschelde estuary

The invertebrate zooplankton fauna of the Westerschelde (Belgium and The Netherlands) was investigated during 2 yr by means of monthly samples along a salinity gradient. Copepods were usually the most abundant holoplanktonic metazoans except in the freshwater zone where Rotifera were most numerous. The combination of a classification technique and an ordination-regression technique proved to be a valuable tool for the analysis of such an extensive data set. The presence of 4 groups was established, representing spatially distinct populations but with temporally shifting boundaries. Few zooplankton species were truly estuarine in their distribution, but many were derived from nearby coastal waters. This intrusion of marine species started in spring, reaching their most upstream distribution and highest densities in summer-early fall, then declining and retreating from the estuary, disappearing in winter. Fringing this community was a transition group with low densities, but many species. This brackish-water community consisted predominantly of the calanoid copepod Eurytemora affinis. It appeared in late fall, spread out seaward to obtain its maximum density and distribution in winter-early spring. Densities then declined and the community was absent by late summer-early fall. The freshwater zone near the port of Antwerp, Belgium, was characterized by a paucity of large zooplankters, despite the high primary production in this zone. This is probably due to the low oxygen availability in this area. A canonical correspondence analysis revealed 2 major environmental axes. The salinity gradient (mainly spatial) explained most of the variance. Strongly correlated with this factor were dissolved oxygen content and secchi disc visibility. The temperature gradient (mainly temporal) was almost perpendicular to the salinity axis, indicating little or no correlation. Of lesser importance was the load of suspended matter, which was highest in the brackish area in autumn-winter. Chlorophyll content of the water was unimportant in explaining community structure. Copepod dry weight was maximal in spring in the brackish part (500 mg m-3); a lower maximum (260 mg m-3) was observed in summer in the marine part of the estuary

Causes of early neonatal respiratory distress in the former Venda - a community-based study

Objective: To determine in a rural black population the incidence of common forms of respiratory distress (RD) and low birth weight (LBW), the mortality from RD and the perinatal mortality rate (PMR). Design: A prospective study in a context in which about 90% of the community's births take place within the health service and unwell neonates are transferred to hospital. Setting: The Donald Fraser health ward, Northern Province (then Venda), which serves a population of about 180 000 through 21 clinics and health centres and a 450 bed hospital. Subjects: 7 539 infants born alive between 1 February 1992 and 31 January 1993, of whom 48 developed RD. Outcome measures: Hjalmarson's classification of RD, modified for local conditions. Criteria depended on clinical signs, chest radiography, neutrophil count in blood and gastric aspirate, blood cultures and postmortem examination. Results: RD 6.4/1 000 livebirths (95% Cl 4.6 - 8.2); infection 2.6/1 000 livebirths (95% Cl 1.4 - 3.7); hyaline membrane disease (HMD) 0.9/1 000 livebirths (95% Cl 0.2 - , .6); pulmonary maladaptation (transient tachypnoea) 0.8/1 000 livebirths (95% Cl 0.2 - 1.4); mortality from RD 2.1/1 000 livebirths (95% CILl - 3.2); incidence of LBW 7.9% (95% Cl 7.3 - 8.5); PMR 19.8/1 000 livebirths (95% Cl 17-23). Conclusion: A strikingly Jow incidence of neonatal AD in general and of HMD in particular was found in a rural black population, probably related to a low LBW incidence. Infection was the commonest cause of RD.S Afr Med J 1996; 86; 1413-1<i1

Negotiating 'Evil': Google, Project Maven and the Corporate Form

‘Don’t be evil’ was part of Google’s corporate code of conduct since 2000; however, it was quietly removed in April or May 2018 and subsequently replaced with ‘do the right thing’. Questions were raised both internally and externally to the organisation regarding the substantive meaning of this imperative. Some have highlighted the company’s original intentions in creating the code of conduct, while others have used the motto as a basis for critiquing the company—such as for its advertising practices, failure to pay corporate tax or the manipulation of Google-owned content. The imperative’s removal occurred at a time when thousands of Google employees, including senior engineers, signed a letter protesting the company’s involvement in Project Maven, a Pentagon program that uses artificial intelligence to interpret video imagery, which could in turn be used to improve the targeting capability of drone strikes. Employees asserted their refusal to be involved in the business of war and expressed their wariness of the United States government’s use of technology. This article will examine the legal construct and concept of the corporation, and whether it is possible for corporations to not be evil in the twenty-first century.</jats:p

Impacts of Ocean Acidification on Sediment Processes in Shallow Waters of the Arctic Ocean

International audienceDespite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO 2 and usually have a lower buffering capacity than warmer waters, acidification rates in these areas are faster than those in subtropical regions. The present study investigates the effects of ocean acidification on sediment composition, processes and sediment-water fluxes in an Arctic coastal system. Undisturbed sediment cores, exempt of large dwelling organisms, were collected, incubated for a period of 14 days, and subject to a gradient of pCO 2 covering the range of values projected for the end of the century. On five occasions during the experimental period, the sediment cores were isolated for flux measurements (oxygen, alkalinity, dissolved inorganic carbon, ammonium, nitrate, nitrite, phosphate and silicate). At the end of the experimental period, denitrification rates were measured and sediment samples were taken at several depth intervals for solid-phase analyses. Most of the parameters and processes (i.e. mineralization, denitrification) investigated showed no relationship with the overlying seawater pH, suggesting that ocean acidification will have limited impacts on the microbial activity and associated sediment-water fluxes on Arctic shelves, in the absence of active bio-irrigating organisms. Only following a pH decrease of 1 pH unit, not foreseen in the coming 300 years, significant enhancements of calcium carbonate dissolution and anammox rates were observed. Longer-term experiments on different sediment types are still required to confirm the limited impact of ocean acidification on shallow Arctic sediment processes as observed in this study

A systematic review of anatomic predictors of abdominal aortic aneurysm remodeling after endovascular repair

Objective: The long-term outcomes after endovascular abdominal aneurysm repair (EVAR) of abdominal aortic aneurysms (AAAs) have been inferior to those after open surgical repair with regard to reinterventions and late mortality. AAA sac remodeling after EVAR has been associated with endoleaks, reinterventions, and mortality. Therefore, knowledge of the predictors of AAA sac remodeling could indirectly give insight into the long-term EVAR outcomes. In the present review, we aimed to provide an overview of the evidence for anatomic predictors of positive and negative AAA sac remodeling after EVAR. Methods: A systematic literature review and analysis were conducted in accordance with the PRISMA (preferred reporting items for systematic reviews and meta-analyses) and Cochrane guidelines. The PubMed and Scopus databases were searched using terms of AAA sac growth, shrinkage, and remodeling. Eligible studies were identified, and only those studies that had included currently used endografts were included. Results: A total of 19 studies that had reported on a total of 27 anatomic parameters of the aortoiliac anatomy were included. Only 4 parameters had been investigated by more than five studies, 7 parameters were investigated by three to five studies, 7 parameters were investigated by two studies, and 9 parameters were investigated by one study. For the presence of neck thrombus, three of four studies had reported similar results, indicating that the presence of neck thrombus might predict for less AAA sac shrinkage. AAA thrombus, the total AAA volume, the flow-lumen volume, aortic calcification, and the number of hostile neck parameters were only investigated by two to three studies. However, these parameters seemed promising for the prediction of sac remodeling. For hostile neck anatomy, neck length, infrarenal neck angulation, and patency of the inferior mesenteric artery, no significant association with any category of AAA sac remodeling was found. Conclusions: The present review demonstrates neck thrombus, AAA thrombus, number of hostile neck parameters, total AAA volume, AAA flow-lumen volume, and aortic calcification as important anatomic features that are likely to play a role in AAA remodeling after endovascular repair and should be further explored using advanced imaging techniques. We also found that strong, consistent evidence regarding the anatomic predictors of AAA sac remodeling after EVAR is lacking. Therefore, further research with large patient groups for a broad range of predictors of AAA sac change after EVAR is needed to complement the current gap in the evidence

The pathophysiological basis of pharmacological interventions in CAVD

Calcific aortic valve disease (CAVD) results in aortic valve stenosis and is one of the most common cardiac diseases in both Western and developing countries. The burden of this disease is expected to increase rapidly in the future, but there are still no relevant pharmacological therapies available and aortic valve replacement remains the sole definite therapy. This review presents an overview of the most common causes of CAVD, followed by current debates and trials related to the onset and progression of this disease. Several differences and similarities between the different causes of CAVD are presented. Additionally, stages of CAVD are compared with stages in atherosclerosis. Finally, future directions for research on CAVD will be discussed