Hydrous Manganese Oxide Doped Gel Probe Sampler for Measuring In Situ Reductive Dissolution Rates. 2. Field Deployment

In situ rates of reductive dissolution in submerged shoreline sediments at Lake Tegel (Berlin, Germany) were measured with a novel hydrous manganese (Mn) oxide-doped gel probe sampler in concert with equilibrium gel probe and sequential extraction measurements. Rates were low in the top 8 cm, then showed a peak from 8 to 14 cm, with a maximum at 12 cm depth. This rate corresponded with a peak in dissolved porewater iron (Fe) at 11 cm depth. Below 14 cm, the reductive dissolution rate reached an intermediate steady value. Lower rates at depth corresponded with increases in operationally defined fractions of carbonate-bound and organic- and sulfide-bound Mn and Fe as detected by sequential extraction. Observed rates of reductive dissolution, which reflect a capacity for Mn reduction rather than actual rates under ambient conditions, appear to correlate with porewater chemistry and sequential extraction fractions as expected in early sediment diagenesis, and are consistent with previous measurements of in situ reductive dissolution rates. Significant downward advection in this bank filtration setting depletes the Mn and Fe oxides in the sediments and enhances the transport of dissolved Fe and Mn into the infiltrating water

Spontaneous Abortion and Preterm Labor and Delivery in Nonhuman Primates: Evidence from a Captive Colony of Chimpanzees (Pan troglodytes)

Preterm birth is a leading cause of perinatal mortality, yet the evolutionary history of this obstetrical syndrome is largely unknown in nonhuman primate species.We examined the length of gestation during pregnancies that occurred in a captive chimpanzee colony by inspecting veterinary and behavioral records spanning a total of thirty years. Upon examination of these records we were able to confidently estimate gestation length for 93 of the 97 (96%) pregnancies recorded at the colony. In total, 78 singleton gestations resulted in live birth, and from these pregnancies we estimated the mean gestation length of normal chimpanzee pregnancies to be 228 days, a finding consistent with other published reports. We also calculated that the range of gestation in normal chimpanzee pregnancies is approximately forty days. Of the remaining fifteen pregnancies, only one of the offspring survived, suggesting viability for chimpanzees requires a gestation of approximately 200 days. These fifteen pregnancies constitute spontaneous abortions and preterm deliveries, for which the upper gestational age limit was defined as 2 SD from the mean length of gestation (208 days).The present study documents that preterm birth occurred within our study population of captive chimpanzees. As in humans, pregnancy loss is not uncommon in chimpanzees, In addition, our findings indicate that both humans and chimpanzees show a similar range of normal variation in gestation length, suggesting this was the case at the time of their last common ancestor (LCA). Nevertheless, our data suggest that whereas chimpanzees' normal gestation length is ∼20-30 days after reaching viability, humans' normal gestation length is approximately 50 days beyond the estimated date of viability without medical intervention. Future research using a comparative evolutionary framework should help to clarify the extent to which mechanisms at work in normal and preterm parturition are shared in these species

The P2X1 receptor and platelet function

Extracellular nucleotides are ubiquitous signalling molecules, acting via the P2 class of surface receptors. Platelets express three P2 receptor subtypes, ADP-dependent P2Y1 and P2Y12 G-protein-coupled receptors and the ATP-gated P2X1 non-selective cation channel. Platelet P2X1 receptors can generate significant increases in intracellular Ca2+, leading to shape change, movement of secretory granules and low levels of αIIbβ3 integrin activation. P2X1 can also synergise with several other receptors to amplify signalling and functional events in the platelet. In particular, activation of P2X1 receptors by ATP released from dense granules amplifies the aggregation responses to low levels of the major agonists, collagen and thrombin. In vivo studies using transgenic murine models show that P2X1 receptors amplify localised thrombosis following damage of small arteries and arterioles and also contribute to thromboembolism induced by intravenous co-injection of collagen and adrenaline. In vitro, under flow conditions, P2X1 receptors contribute more to aggregate formation on collagen-coated surfaces as the shear rate is increased, which may explain their greater contribution to localised thrombosis in arterioles compared to venules within in vivo models. Since shear increases substantially near sites of stenosis, anti-P2X1 therapy represents a potential means of reducing thrombotic events at atherosclerotic plaques

A 'snip' in time: what is the best age to circumcise?

<p>Abstract</p> <p>Background</p> <p>Circumcision is a common procedure, but regional and societal attitudes differ on whether there is a need for a male to be circumcised and, if so, at what age. This is an important issue for many parents, but also pediatricians, other doctors, policy makers, public health authorities, medical bodies, and males themselves.</p> <p>Discussion</p> <p>We show here that infancy is an optimal time for clinical circumcision because an infant's low mobility facilitates the use of local anesthesia, sutures are not required, healing is quick, cosmetic outcome is usually excellent, costs are minimal, and complications are uncommon. The benefits of infant circumcision include prevention of urinary tract infections (a cause of renal scarring), reduction in risk of inflammatory foreskin conditions such as balanoposthitis, foreskin injuries, phimosis and paraphimosis. When the boy later becomes sexually active he has substantial protection against risk of HIV and other viral sexually transmitted infections such as genital herpes and oncogenic human papillomavirus, as well as penile cancer. The risk of cervical cancer in his female partner(s) is also reduced. Circumcision in adolescence or adulthood may evoke a fear of pain, penile damage or reduced sexual pleasure, even though unfounded. Time off work or school will be needed, cost is much greater, as are risks of complications, healing is slower, and stitches or tissue glue must be used.</p> <p>Summary</p> <p>Infant circumcision is safe, simple, convenient and cost-effective. The available evidence strongly supports infancy as the optimal time for circumcision.</p

ISSN exercise & sport nutrition review: research & recommendations

Sports nutrition is a constantly evolving field with hundreds of research papers published annually. For this reason, keeping up to date with the literature is often difficult. This paper is a five year update of the sports nutrition review article published as the lead paper to launch the JISSN in 2004 and presents a well-referenced overview of the current state of the science related to how to optimize training and athletic performance through nutrition. More specifically, this paper provides an overview of: 1.) The definitional category of ergogenic aids and dietary supplements; 2.) How dietary supplements are legally regulated; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of the ergogenic value of nutrition and dietary supplementation in regards to weight gain, weight loss, and performance enhancement. Our hope is that ISSN members and individuals interested in sports nutrition find this review useful in their daily practice and consultation with their clients

Potential for release of sediment phosphorus to Lake Powell (Utah and Arizona) due to sediment resuspension during low water level

The water level in Lake Powell, an important water-supply reservoir on the Colorado River, United States, decreased in most years from 1999 to 2010, exposing the sediment delta in the inflow region of this reservoir. This study assesses the potential for sediment-associated phosphorus (P) to enter the water column during sediment resuspension. We collected sediment samples from the reservoir inflow region and performed a sequential extraction and a sorption experiment that focused on P. We also collected water samples at locations upstream and downstream of the exposed sediment delta and measured soluble reactive P during base flow and during the yearly flood associated with spring runoff. Results indicate that extractable P is associated with various operationally defined fractions as follows: 50% with calcite and biogenic apatite, 29% with detrital apatite, 10% with Fe(III)-oxide minerals, 6% with organic matter and 4% with easily exchangeable solid-phase association sites. Sorption experiments indicate that the equilibrium P concentration is 0.19 ± 0.07 μM. Particle size is correlated with sediment P; coarse sediment contains and sorbs much less extractable P than fine sediment does. Measurements of water samples indicate that sediment resuspension probably releases P from sediment to overlying water during base flow, but the effect during floods is less clear. These results indicate that lowering reservoir levels introduces sediment-associated P to the reservoir when sediment resuspension occurs

Effect of a moderate-size reservoir on transport of trace elements in a watershed

<p>Wildman RA, Forde NA. 2016. Effect of a moderate-size reservoir on transport of trace elements in a watershed. Lake Reserve Manage. 32:353–365.</p> <p>We assessed the extent to which Grand Lake, Oklahoma (>30 m deep, >80 km long), retains Fe, Mn, P, As, Zn, Pb, and Cd. Filtered water samples and suspended sediment samples were collected upstream of, within, and downstream of the reservoir. We then estimated instantaneous, seasonal, elemental fluxes. In winter and spring, when storms brought high flows to the reservoir, Grand Lake modified flood water minimally. During these seasons, trace element distributions were determined by the passage of storm inflows through the reservoir. In summer, Fe, Mn, P, and As were enriched in anoxic bottom water and exported through the dam, which draws water from below the surface mixed layer. Concentrations of aqueous elements in the water column were lower following autumn overturn, perhaps due to precipitation of metal oxides and settling. Unlike Fe, Zn was retained in Grand Lake during all seasons. Concentrations of Cd and Pb in filtered samples were often below our detection limit. Logistic regression indicated that Zn predicted detectable Cd, and so Grand Lake probably sequesters Cd. Sequestration of Pb was unclear because detectable Pb was predicted by both Zn and Fe. This study shows that watershed hydrology determines the transport of trace elements through a reservoir during times of high flow but that vertical circulation and biogeochemistry dominate during summertime and autumn low flows. Understanding these mechanisms can aid reservoir managers who seek to reduce downstream loads of trace elements.</p

Turbid releases from Glen Canyon Dam, Arizona, following rainfall-runoff events of September 2013

<p>Wildman RA Jr, Vernieu WS. 2017. Turbid releases from Glen Canyon Dam, Arizona, following rainfall-runoff events of September 2013. Lake Reserv Manage. 00:1–6.</p> <p>Glen Canyon Dam is a large dam on the Colorado River in Arizona. In September 2013, it released turbid water following intense thunderstorms in the surrounding area. Turbidity was >15 nephelometric turbidity units (NTU) for multiple days and >30 NTU at its peak. These unprecedented turbid releases impaired downstream fishing activity and motivated a rapid-response field excursion. At 5 locations upstream from the dam, temperature, specific conductance, dissolved oxygen, chlorophyll <i>a</i>, and turbidity were measured in vertical profiles. Local streamflow and rainfall records were retrieved, and turbidity and specific conductance data in dam releases were evaluated. Profiling was conducted to determine possible sources of turbidity from 3 tributaries nearest the dam, Navajo, Antelope, and Wahweap creeks, which entered Lake Powell as interflows during this study. We discuss 4 key conditions that must have been met for tributaries to influence turbidity of dam releases: tributary flows must have reached the dam, tributary flows must have been laden with sediment, inflow currents must have been near the depth of dam withdrawals, and the settling velocity of particles must have been slow. We isolate 2 key uncertainties that reservoir managers should resolve in future similar studies: the reach of tributary water into the reservoir thalweg and the distribution of particle size of suspended sediment. These uncertainties leave the source of the turbidity ambiguous, although an important role for Wahweap Creek is possible. The unique combination of limnological factors we describe implies that turbid releases at Glen Canyon Dam will continue to be rare.</p

Hydrologic and Biogeochemical Controls of River Subsurface Solutes under Agriculturally Enhanced Ground Water Flow

The relative influences of hydrologic processes and biogeochemistry on the transport and retention of minor solutes were compared in the riverbed of the lower Merced River (California, USA). The subsurface of this reach receives ground water discharge and surface water infiltration due to an altered hydraulic setting resulting from agricultural irrigation. Filtered ground water samples were collected from 30 drive point locations in March, June, and October 2004. Hydrologic processes, described previously, were verified by observations of bromine concentrations; manganese was used to indicate redox conditions. The separate responses of the minor solutes strontium, barium, uranium, and phosphorus to these influences were examined. Correlation and principal component analyses indicate that hydrologic processes dominate the distribution of trace elements in the ground water. Redox conditions appear to be independent of hydrologic processes and account for most of the remaining data variability. With some variability, major processes are consistent in two sampling transects separated by 100 m