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.

Design of Continuous Prestressed Concrete Spliced Girder Bridges

Traditionally, prestressed concrete girder bridges are limited to 150 ft span lengths in Texas due to restrictions on handling and transportation. An effective way of increasing span lengths of precast, prestressed concrete girder bridges is demonstrated using splicing technique. In spliced girder bridges, precast girder segments are transported in shorter segments for handling and transportation and then spliced together to form long-span continuous bridges. Different methods are explored for construction of spliced girder bridges. Two application examples are developed to demonstrate the design of continuous prestressed concrete spliced girder bridges for both shored and partially shored methods of construction. A three-span bridge having a span configuration of 190-240-190 ft is considered for both examples. Advantages and dis-advantages of each method of construction are discussed. Construction issues that should be considered in the design are highlighted. The results of this study indicate that span lengths up to 240 ft are achievable using standard Tx70 girders with the help of splicing techniques. A parametric study is performed to further explore the design space of spliced girder bridges. The results of the parametric study, along with critical design issues that were identified, are highlighted and related recommendations are provided. The results of this study will be of significant interest to bridge engineers and researchers for guidance in implementing spliced girder bridges in Texas and other states

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.

Systematic review of public health research on prevention of mother-to-child transmission of HIV in India with focus on provision and utilization of cascade of PMTCT services

BACKGROUND: In spite of effective strategies to eliminate mother-to-child-transmission of HIV, the implementation of such strategies remains a major challenge in developing countries. In India, programs for the prevention of mother-to-child transmission (PMTCT) have been scaled up widely since 2005. However, these programs reach only a small percentage of pregnant women, and their overall effectiveness is low. Evidence-based program planning and implementation could significantly improve their effectiveness. This study sought to systematically retrieve, thematically categorize and review published research on PMTCT of HIV in India, focusing on research related to the provision and/or utilization of the cascade of services provided in a PMTCT program, in order to direct further research to enhance program implementation and effectiveness. METHODS: A systematic search using MEDLINE, US National Library of Medicine Gateway system (PubMed) and ISI Web of Knowledge resulted in 1,944 abstracts, of which 167 met our inclusion criteria. RESULTS: A huge share of the empirical literature on PMTCT in India (N = 134) deals with epidemiological studies (N = 60). The 46 papers related to utilization/provision of the cascade of PMTCT services were mostly from the four high HIV prevalence states in southern India and from the public sector. Studies on experiences of implementing a PMTCT program (N = 20) show high rates of drop out of women in the cascade particularly prior to receiving ARV. Studies on individual components of the cascade (N = 26) show that HIV counseling and testing is acceptable and feasible. Literature on other components of the cascade - such as pregnant women’s access to ANC care, HIV infected women’s immunological assessment using CD4 testing, repeat HIV testing among pregnant women, early infant diagnosis and factors related to linking HIV infected women and children to postnatal care – is lacking. CONCLUSIONS: While the scale of the Indian PMTCT program is large, comprehensive understanding of the context-driven factors affecting its efficiency is lacking. Systematic and more focused public health research output is needed on the issues related to reduction of drop outs of women in the cascade, role of PMTCT programs in improving maternal and child health indicators and role of private sector in delivering PMTCT services

Efficacy of virtual reality for pain relief in medical procedures: A systematic review and meta-analysis

BackgroundEffective pain control is crucial to optimise the success of medical procedures. Immersive virtual reality (VR) technology could offer an effective non-invasive, non-pharmacological option to distract patients and reduce their experience of pain. We aimed to evaluate the efficacy of Immersive virtual reality (VR) technology in reducing patient’s pain perception during various medical procedures by conducting a systematic review and meta-analysis.MethodsWe searched MEDLINE, EMBASE, CENTRAL, CINAHL, and SIGLE until December 2022 for all randomised clinical trials (RCT) evaluating any type of VR in patients undergoing any medical procedure. We conducted a random effect meta-analysis summarising standardised mean differences (SMD) with 95% confidence intervals (CI). We evaluated heterogeneity using I 2 and explored it using subgroup and meta-regression analyses.ResultsIn total, we included 92 RCTs (n = 7133 participants). There was a significant reduction in pain scores with VR across all medical procedures (n = 83, SMD − 0.78, 95% CI − 1.00 to − 0.57, I 2 = 93%, p = < 0.01). Subgroup analysis showed varied reduction in pain scores across trial designs [crossover (n = 13, SMD − 0.86, 95% CI − 1.23 to − 0.49, I 2 = 72%, p = < 0.01) vs parallel RCTs (n = 70, SMD − 0.77, 95% CI − 1.01 to − 0.52, I 2 = 90%, p = < 0.01)]; participant age groups [paediatric (n = 43, SMD − 0.91, 95% CI − 1.26 to − 0.56, I 2 = 87%, p = < 0.01) vs adults (n = 40, SMD − 0.66, 95% CI − 0.94 to − 0.39, I 2 = 89%, p = < 0.01)] or procedures [venepuncture (n = 32, SMD − 0.99, 95% CI − 1.52 to − 0.46, I 2 = 90%, p = < 0.01) vs childbirth (n = 7, SMD − 0.99, 95% CI − 1.59 to − 0.38, I 2 = 88%, p = < 0.01) vs minimally invasive medical procedures (n = 25, SMD − 0.51, 95% CI − 0.79 to − 0.23, I 2 = 85%, p = < 0.01) vs dressing changes in burn patients (n = 19, SMD − 0.8, 95% CI − 1.16 to − 0.45, I 2 = 87%, p = < 0.01)]. We explored heterogeneity using meta-regression which showed no significant impact of different covariates including crossover trials (p = 0.53), minimally invasive procedures (p = 0.37), and among paediatric participants (p = 0.27). Cumulative meta-analysis showed no change in overall effect estimates with the additional RCTs since 2018.ConclusionsImmersive VR technology offers effective pain control across various medical procedures, albeit statistical heterogeneity. Further research is needed to inform the safe adoption of this technology across different medical disciplines

Adverse events in people taking macrolide antibiotics versus placebo for any indication

BACKGROUND: Macrolide antibiotics (macrolides) are among the most commonly prescribed antibiotics worldwide and are used for a wide range of infections. However, macrolides also expose people to the risk of adverse events. The current understanding of adverse events is mostly derived from observational studies, which are subject to bias because it is hard to distinguish events caused by antibiotics from events caused by the diseases being treated. Because adverse events are treatment-specific, rather than disease-specific, it is possible to increase the number of adverse events available for analysis by combining randomised controlled trials (RCTs) of the same treatment across different diseases. OBJECTIVES:To quantify the incidences of reported adverse events in people taking macrolide antibiotics compared to placebo for any indication. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which includes the Cochrane Acute Respiratory Infections Group Specialised Register (2018, Issue 4); MEDLINE (Ovid, from 1946 to 8 May 2018); Embase (from 2010 to 8 May 2018); CINAHL (from 1981 to 8 May 2018); LILACS (from 1982 to 8 May 2018); and Web of Science (from 1955 to 8 May 2018). We searched clinical trial registries for current and completed trials (9 May 2018) and checked the reference lists of included studies and of previous Cochrane Reviews on macrolides. SELECTION CRITERIA: We included RCTs that compared a macrolide antibiotic to placebo for any indication. We included trials using any of the four most commonly used macrolide antibiotics: azithromycin, clarithromycin, erythromycin, or roxithromycin. Macrolides could be administered by any route. Concomitant medications were permitted provided they were equally available to both treatment and comparison groups. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted and collected data. We assessed the risk of bias of all included studies and the quality of evidence for each outcome of interest. We analysed specific adverse events, deaths, and subsequent carriage of macrolide-resistant bacteria separately. The study participant was the unit of analysis for each adverse event. Any specific adverse events that occurred in 5% or more of any group were reported. We undertook a meta-analysis when three or more included studies reported a specific adverse event. MAIN RESULTS: We included 183 studies with a total of 252,886 participants (range 40 to 190,238). The indications for macrolide antibiotics varied greatly, with most studies using macrolides for the treatment or prevention of either acute respiratory tract infections, cardiovascular diseases, chronic respiratory diseases, gastrointestinal conditions, or urogynaecological problems. Most trials were conducted in secondary care settings. Azithromycin and erythromycin were more commonly studied than clarithromycin and roxithromycin.Most studies (89%) reported some adverse events or at least stated that no adverse events were observed.Gastrointestinal adverse events were the most commonly reported type of adverse event. Compared to placebo, macrolides caused more diarrhoea (odds ratio (OR) 1.70, 95% confidence interval (CI) 1.34 to 2.16; low-quality evidence); more abdominal pain (OR 1.66, 95% CI 1.22 to 2.26; low-quality evidence); and more nausea (OR 1.61, 95% CI 1.37 to 1.90; moderate-quality evidence). Vomiting (OR 1.27, 95% CI 1.04 to 1.56; moderate-quality evidence) and gastrointestinal disorders not otherwise specified (NOS) (OR 2.16, 95% CI 1.56 to 3.00; moderate-quality evidence) were also reported more often in participants taking macrolides compared to placebo.The number of additional people (absolute difference in risk) who experienced adverse events from macrolides was: gastrointestinal disorders NOS 85/1000; diarrhoea 72/1000; abdominal pain 62/1000; nausea 47/1000; and vomiting 23/1000.The number needed to treat for an additional harmful outcome (NNTH) ranged from 12 (95% CI 8 to 23) for gastrointestinal disorders NOS to 17 (9 to 47) for abdominal pain; 19 (12 to 33) for diarrhoea; 19 (13 to 30) for nausea; and 45 (22 to 295) for vomiting.There was no clear consistent difference in gastrointestinal adverse events between different types of macrolides or route of administration.Taste disturbances were reported more often by participants taking macrolide antibiotics, although there were wide confidence intervals and moderate heterogeneity (OR 4.95, 95% CI 1.64 to 14.93; Iand#178; = 46%; low-quality evidence).Compared with participants taking placebo, those taking macrolides experienced hearing loss more often, however only four studies reported this outcome (OR 1.30, 95% CI 1.00 to 1.70; Iand#178; = 0%; low-quality evidence).We did not find any evidence that macrolides caused more cardiac disorders (OR 0.87, 95% CI 0.54 to 1.40; very low-quality evidence); hepatobiliary disorders (OR 1.04, 95% CI 0.27 to 4.09; very low-quality evidence); or changes in liver enzymes (OR 1.56, 95% CI 0.73 to 3.37; very low-quality evidence) compared to placebo.We did not find any evidence that appetite loss, dizziness, headache, respiratory symptoms, blood infections, skin and soft tissue infections, itching, or rashes were reported more often by participants treated with macrolides compared to placebo.Macrolides caused less cough (OR 0.57, 95% CI 0.40 to 0.80; moderate-quality evidence) and fewer respiratory tract infections (OR 0.70, 95% CI 0.62 to 0.80; moderate-quality evidence) compared to placebo, probably because these are not adverse events, but rather characteristics of the indications for the antibiotics. Less fever (OR 0.73, 95% 0.54 to 1.00; moderate-quality evidence) was also reported by participants taking macrolides compared to placebo, although these findings were non-significant.There was no increase in mortality in participants taking macrolides compared with placebo (OR 0.96, 95% 0.87 to 1.06; Iand#178; = 11%; low-quality evidence).Only 24 studies (13%) provided useful data on macrolide-resistant bacteria. Macrolide-resistant bacteria were more commonly identified among participants immediately after exposure to the antibiotic. However, differences in resistance thereafter were inconsistent.Pharmaceutical companies supplied the trial medication or funding, or both, for 91 trials. AUTHORS' CONCLUSIONS: The macrolides as a group clearly increased rates of gastrointestinal adverse events. Most trials made at least some statement about adverse events, such as "none were observed". However, few trials clearly listed adverse events as outcomes, reported on the methods used for eliciting adverse events, or even detailed the numbers of people who experienced adverse events in both the intervention and placebo group. This was especially true for the adverse event of bacterial resistance.</p

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