Barrier island erosion and overwash study -- effect of seawalls. Volume 2

This is the second of a pair of reports documenting the effects of storms on beach systems including the presence of seawalls. With the aim of simulating the effects of overwash on barrier islands with seawalls and characterizing their response, a series of eight experiments was conducted at the Coastal Engineering Laboratory of the University of Florida. The barrier island was simulated by a 400 feet wide horizontal crest and an initially uniform mildly-sloped (1:19) beach. The effects of positioning the seawall at two different locations as well as the effects of various storm surge levels and accompanying overtopping were investigated. Experiments were conducted with both regular and irregular storm waves. With the seawall located at the slope break between the crest and the sloping beach of the barrier island, and the crest of the seawall just submerged in sand, the effects on the sediment transport process were found to be minimal. For the same position of the seawall but with the crest of the seawall raised above the surrounding ground level, overtopping caused washover of sand indicating substantial transport in suspension. Increased levels of overtopping tended to accentuate bed profile changes but supress bar formation (as did irregular waves). Positioning the seawall at the Mean Sea Level shoreline caused significant scour both immediately landward as well as immediately seaward of the seawall. A prominent scour trough developed further seaward. The longshore bar was highly three-dimensional. It appears that seawalls need to be located adequately landward of the shoreline to discharge their function effectively without adverse effect to the beach. In addition, concerns for safety warrant the presence of an adequate buffer-zone between the seawall and the upland property. (61 pp.

Barrier island erosion and overwash study - volume 1

This is the first of a pair of reports documenting the effects of storms on barrier island systems. The present report (Volume 1) investigates storm effects on natural island conditions whereas Volume 2 addresses the effects of seawalls. With the aim of simulating the effects of overwash on barrier islands and characterizing their response, a series of nine experiments was conducted at the Coastal Engineering Laboratory of the University of Florida. The barrier island was simulated by a 400 feet wide (prototype units) horizontal crest and an initially planar (1:19) beach. The effects of various storm surge levels and accompanying overtopping were investigated. Experiments were conducted with both regular and irregular storm waves. Regular waves without overtopping caused the formation of a substantial berm in the swash zone and a prominent longshore bar offshore. Increasing degrees of overtopping resulted in substantial loss of sand from the barrier island system. The longshore bar was considerably more subtle for the highest water level tested (11.5 ft. above mean sea level). Simulation of a storm-surge hydrograph with rising and falling water levels indicated that the presence of the bar tends to occur only during a relatively steady or slowly changing water level. The experiments with irregular waves were conducted with reasonably similar wave heights and carrier periods as those with regular waves. The major difference was in the characteristics of the longshore bar response. In comparison with cases with regular waves, the bar was less distinct without overtopping, subtle with minimal overtopping and absent in cases with substantial overtopping. These experiments seem to indicate that offshore bars are simply break-point bars which require a fairly steady break-point and undertow (return of mass transport) for optimal formation. (Document has 84 pages.

Characterizing wave- and current- induced bottom shear stress : U.S. middle Atlantic continental shelf

This paper is not subject to U.S. copyright. The definitive version was published in Continental Shelf Research 52 (2013): 73-86, doi:10.1016/j.csr.2012.10.012.Waves and currents create bottom shear stress, a force at the seabed that influences sediment texture distribution, micro-topography, habitat, and anthropogenic use. This paper presents a methodology for assessing the magnitude, variability, and driving mechanisms of bottom stress and resultant sediment mobility on regional scales using numerical model output. The analysis was applied to the Middle Atlantic Bight (MAB), off the U.S. East Coast, and identified a tidally-dominated shallow region with relatively high stress southeast of Massachusetts over Nantucket Shoals, where sediment mobility thresholds are exceeded over 50% of the time; a coastal band extending offshore to about 30 m water depth dominated by waves, where mobility occurs more than 20% of the time; and a quiescent low stress region southeast of Long Island, approximately coincident with an area of fine-grained sediments called the “Mud Patch”. The regional high in stress and mobility over Nantucket Shoals supports the hypothesis that fine grain sediment winnowed away in this region maintains the Mud Patch to the southwest. The analysis identified waves as the driving mechanism for stress throughout most of the MAB, excluding Nantucket Shoals and sheltered coastal bays where tides dominate; however, the relative dominance of low-frequency events varied regionally, and increased southward toward Cape Hatteras. The correlation between wave stress and local wind stress was lowest in the central MAB, indicating a relatively high contribution of swell to bottom stress in this area, rather than locally generated waves. Accurate prediction of the wave energy spectrum was critical to produce good estimates of bottom shear stress, which was sensitive to energy in the long period waves.P.S. Dalyander was supported by the U.S. Geological Survey Mendenhall Research Fellowship Program

Advances in the prevention of mother-to-child transmission of HIV and resulting clinical and programmatic implications

Shrinivas Darak,1,2 Ritu Parchure,2 Trupti Darak,2 Rachel Talavlikar,3 Sanjeevani Kulkarni,2 Vinay Kulkarni2 1Population Research Centre, Faculty of Spatial Sciences, University of Groningen, the Netherlands; 2PRAYAS Health Group, Pune, India; 3Department of Family Medicine, University of Calgary, Calgary, AB, Canada Abstract: Following scientific advancements in the prevention of mother-to-child transmission (PMTCT) of HIV, a global plan is being implemented to virtually eliminate new pediatric HIV infections. However, despite revisions to guidelines for providing antiretroviral medications, including the availability of more effective drug regimens over the past decade, and the recent rapid scale-up of PMTCT services, sizeable challenges persist in achieving this goal. This paper provides a summary of recent approaches to the provision of antiretroviral medicines to pregnant women and the resulting implications. Emerging programmatic and service delivery considerations, aiming to increase the effectiveness of PMTCT programs to overcome barriers faced by women in accessing PMTCT services are also discussed. Worldwide elimination of pediatric HIV is now a possibility due to the increasing similarity of PMTCT guidelines in developing countries to those in developed countries. However the resulting practical challenges of implementation will require resources and support at local, national, and international levels. As developing countries strive to adopt and implement more efficacious drug regimens, the effectiveness of PMTCT programs will be determined by coverage of services and the recruitment and retention of pregnant women in the cascade. To expand services and provide an effective, comprehensive approach in under resourced settings, harmonized efforts to address barriers whilst considering contextual factors will be needed. Keywords: PMTCT, HIV, ARVs, program implementatio

HSV-1 miRNAs are post-transcriptionally edited in latently infected human ganglia

Herpes simplex virus 1 is an important human pathogen that has been intensively studied for many decades. Nevertheless, the molecular mechanisms regulating its establishment, maintenance, and reactivation from latency are poorly understood. Here, we show that HSV-1-encoded miR-H2 is post-transcriptionally edited in latently infected human tissues. Hyperediting of viral miRNAs increases the targeting potential of these miRNAs and may play an important role in regulating latency. We show that the edited miR-H2 can target ICP4, an essential viral protein. Interestingly, we found no evidence of hyperediting of its homolog, miR-H2, which is expressed by the closely related virus HSV-2. The discovery of post-translational modifications of viral miRNA in the latency phase suggests that these processes may also be important for other non-coding viral RNA in the latency phase, including the intron LAT, which in turn may be crucial for understanding the biology of this virus

Liquid-liquid phase separation facilitates the biogenesis of secretory storage granules.

Funder: Yale-start up grantFunder: NIGMS NIH HHSFunder: Fraternal Order of Eagles Diabetes Research CenterFunder: Sir Henry DaleFunder: University of IowaFunder: PI Daniel EberlFunder: Royal Society210481Insulin is synthesized by pancreatic β-cells and stored into secretory granules (SGs). SGs fuse with the plasma membrane in response to a stimulus and deliver insulin to the bloodstream. The mechanism of how proinsulin and its processing enzymes are sorted and targeted from the trans-Golgi network (TGN) to SGs remains mysterious. No cargo receptor for proinsulin has been identified. Here, we show that chromogranin (CG) proteins undergo liquid-liquid phase separation (LLPS) at a mildly acidic pH in the lumen of the TGN, and recruit clients like proinsulin to the condensates. Client selectivity is sequence-independent but based on the concentration of the client molecules in the TGN. We propose that the TGN provides the milieu for converting CGs into a "cargo sponge" leading to partitioning of client molecules, thus facilitating receptor-independent client sorting. These findings provide a new receptor-independent sorting model in β-cells and many other cell types and therefore represent an innovation in the field of membrane trafficking