Inorganic chemical oxygen demand of re-suspended sediments in a bar-built lagoon

Rapid dissolved oxygen (DO) depletion, caused by inorganic chemical oxygen demand (COD) of re-suspended sediment compounds, has been documented in few studies, yet fish kills occur often from the process. Pescadero Lagoon, California, USA, a bar-built lagoon that suffers annual fish kills caused by rapid mixing-induced hypoxia upon sandbar breach, was studied to investigate the potential for COD of re-suspended sediment to deplete oxygen. In-situ chamber mixing trials demonstrated that re-suspended sediment can exert powerful oxygen demand on receiving waters. Surface DO depletion upon bar breach was too severe to be explained solely by mixing of the anoxic hypolimnion into the water column, and the depletion was too rapid to be attributed to biochemical oxygen demand (BOD), making COD of re-suspended sediment the likely direct cause. Sedimentous iron and sulfur compounds that exert COD are reduced under anoxic conditions created by water column stratification and BOD of heterotrophic bacteria

Three-Omega Thermal-Conductivity Measurements with Curved Heater Geometries

The three-omega method, a powerful technique to measure the thermal conductivity of nanometer-thick films and the interfaces between them, has historically employed straight conductive wires to act as both heaters and thermometers. When investigating stochastically prepared samples such as two-dimensional materials and nanomembranes, residue and excess material can make it difficult to fit the required millimeter-long straight wire on the sample surface. There are currently no available criteria for how diverting three-omega heater wires around obstacles affects the validity of the thermal measurement. In this Letter, we quantify the effect of wire curvature by performing three-omega experiments with a wide range of frequencies using both curved and straight heater geometries on SiO$_2$/Si samples. When the heating wire is curved, we find that the measured Si substrate thermal conductivity changes by only 0.2%. Similarly, we find that wire curvature has no significant effect on the determination of the thermal resistance of a $\sim$65 nm SiO$_2$ layer, even for the sharpest corners considered here, for which the largest measured ratio of the thermal penetration depth of the applied thermal wave to radius of curvature of the heating wire is 4.3. This result provides useful design criteria for three-omega experiments by setting a lower bound for the maximum ratio of thermal penetration depth to wire radius of curvature.Comment: 4 pages, 3 figure

Improving graduate attributes within the Egyptian university sector.

Throughout the years universities have attempted to foster graduate attributes in undergraduate degree courses. Despite the initiatives and funds put in place, attempts have been met with limited success causing what is known as the skills gap. This study sets out to understand the causes underpinning the skills gap by examining the specific nature of graduate attributes through using complexity theory. It builds on earlier work into graduate attributes by investigating the reasons influencing the variation in their interpretation thus providing an analysis of their contextual nature. Rather than determining key factors, this paper examines the multi factor causalities that affect the teaching and learning of graduate attributes in their educational context which requires to be acknowledged in higher education policies and practices. The study was explored in the Egyptian computer engineering undergraduate context. Using semi-structured interviews, a number of questions were posed to a purposive sample of academics and graduates belonging to two different computer engineering undergraduate programmes; one that is private and another that is public. To ensure the validity of data, more data were collected from Egyptian employers as well as the documents that represent the different educational policies and practices implemented in both private and public programmes of study. This research could be of interest to higher education authorities including: universities, deans of faculties, and heads of academic programmes, academics teaching undergraduate bachelor degrees, and course designers and reviewers for undergraduate bachelor degrees

Treatment of missing data in Bayesian network structure learning : an application to linked biomedical and social survey data

The authors acknowledge the Research/Scientific Computing teams at The James Hutton Institute and NIAB for providing computational resources and technical support for the “UK’s Crop Diversity Bioinformatics HPC” (BBSRC grant BB/S019669/1), use of which has contributed to the results reported within this paper. Access to this was provided via the University of St Andrews Bioinformatics Unit which is funded by a Wellcome Trust ISSF award (grant 105621/Z/14/Z and 204821/Z/16/Z). XK was supported by a World-Leading PhD Scholarship from St Leonard’s Postgraduate School of the University of St Andrews. VAS and KK were partially supported by HATUA, The Holistic Approach to Unravel Antibacterial Resistance in East Africa, a three-year Global Context Consortia Award (MR/S004785/1) funded by the National Institute for Health Research, Medical Research Council and the Department of Health and Social Care. KK is supported by the Academy of Medical Sciences, the Wellcome Trust, the Government Department of Business, Energy and Industrial Strategy, the British Heart Foundation Diabetes UK, and the Global Challenges Research Fund [Grant number SBF004\1093]. KK is additionally supported by the Economic and Social Research Council HIGHLIGHT CPC- Connecting Generations Centre [Grant number ES/W002116/1].Background Availability of linked biomedical and social science data has risen dramatically in past decades, facilitating holistic and systems-based analyses. Among these, Bayesian networks have great potential to tackle complex interdisciplinary problems, because they can easily model inter-relations between variables. They work by encoding conditional independence relationships discovered via advanced inference algorithms. One challenge is dealing with missing data, ubiquitous in survey or biomedical datasets. Missing data is rarely addressed in an advanced way in Bayesian networks; the most common approach is to discard all samples containing missing measurements. This can lead to biased estimates. Here, we examine how Bayesian network structure learning can incorporate missing data. Methods We use a simulation approach to compare a commonly used method in frequentist statistics, multiple imputation by chained equations (MICE), with one specific for Bayesian network learning, structural expectation-maximization (SEM). We simulate multiple incomplete categorical (discrete) data sets with different missingness mechanisms, variable numbers, data amount, and missingness proportions. We evaluate performance of MICE and SEM in capturing network structure. We then apply SEM combined with community analysis to a real-world dataset of linked biomedical and social data to investigate associations between socio-demographic factors and multiple chronic conditions in the US elderly population. Results We find that applying either method (MICE or SEM) provides better structure recovery than doing nothing, and SEM in general outperforms MICE. This finding is robust across missingness mechanisms, variable numbers, data amount and missingness proportions. We also find that imputed data from SEM is more accurate than from MICE. Our real-world application recovers known inter-relationships among socio-demographic factors and common multimorbidities. This network analysis also highlights potential areas of investigation, such as links between cancer and cognitive impairment and disconnect between self-assessed memory decline and standard cognitive impairment measurement. Conclusion Our simulation results suggest taking advantage of the additional information provided by network structure during SEM improves the performance of Bayesian networks; this might be especially useful for social science and other interdisciplinary analyses. Our case study show that comorbidities of different diseases interact with each other and are closely associated with socio-demographic factors.PostprintPublisher PDFPeer reviewe

The Effectiveness of the Critical Power Model on Prescribing Elements of Intermittent Exercise

Intermittent exercise is a valuable method of training, consisting of numerous interrelated factors. The critical power model has been used to administer interval training programs; however, it has not been used to accurately prescribe elements of intermittent exercise. PURPOSE: This study aimed to use individual critical power models to prescribe elements of intermittent exercise. METHODS: Ten male athletes, mean (sd) age and mass 19.6 (1.4) years and 77.8 (8.1) kg performed three phases of testing on a cycle ergometer: 1) familiarization, one learning trial to establish a starting point for subsequent tests; 2) establishment of individual W/t relationship from [Eq 1], i.e. t = W’ / (W – WCP), 4 bouts of exercise designed to elicit fatigue in 2-15 minutes; 3) intermittent exercise, 3 bouts of work with predicted number of work/recovery cycles (n = 5) of 60/60 s, 120/60 s, and 60/120 s. The elements of these bouts were prescribed using [Eq 2], i.e. n = W’ / ((Ww – WCP)tw – (WCP – Wr)tr) and estimates of W’ and CP from phase 2 of testing. One sample t-tests were used to compare the number of cycles actually completed to the predicted value of 5 cycles for each intermittent exercise bout. A repeated-measures ANOVA was used to compare the effect of intermittent exercise on the number of work/recovery cycles completed across conditions. RESULTS: The mean (sd) completed work/recovery cycles were 4.64 (0.47), 4.65 (1.10), and 3.70 (0.80), for the 60/60 s, 120/60 s, and 60/120 s trials, respectively. Results of the t-tests suggested that actual values were not significantly different from predicted for 60/60 s and 120/60 s (t(9) = -2.39, p = 0.04; t(9) = -1.01, p = 0.34), but were for 60/120 s (t(9) = -5.14, p \u3c 0.01). Results of the rANOVA suggested that the mean completed work/recovery cycles was significantly different across conditions (F(2,18) = 3.99, p = 0.04). DISCUSSION: These data suggest that using [Eq 2], with estimates of W’ and CP from [Eq 1], to prescribe elements of intermittent exercise can be successful for trials with short recovery periods

Attack of the Flying Snakes : Formation of Isolated HI Clouds By Fragmentation of Long Streams

The existence of long (> 100 kpc) HI streams and small (< 20 kpc) free-floating HI clouds is well-known. While the formation of the streams has been investigated extensively, and the isolated clouds are often purported to be interaction debris, little research has been done on the formation of optically dark HI clouds that are not part of a larger stream. One possibility is that such features result from the fragmentation of more extended streams, while another idea is that they are primordial, optically dark galaxies. We test the validity of the fragmentation scenario (via harassment) using numerical simulations. In order to compare our numerical models with observations, we present catalogues of both the known long HI streams (42 objects) and free-floating HI clouds suggested as dark galaxy candidates (51 objects). In particular, we investigate whether it is possible to form compact features with high velocity widths (> 100 km/s), similar to observed clouds which are otherwise intriguing dark galaxy candidates. We find that producing such features is possible but extremely unlikely, occurring no more than 0.2% of the time in our simulations. In contrast, we find that genuine dark galaxies could be extremely stable to harassment and remain detectable even after 5 Gyr in the cluster environment (with the important caveat that our simulations only explore harassment and do not yet include the intracluster medium, heating and cooling, or star formation). We also discuss the possibility that such objects could be the progenitors of recently discovered ultra diffuse galaxies.Comment: 46 pages, 27 figures, accepted for publication in MNRA

Hydroxyurea Therapy in UK Children with Sickle Cell Anaemia – A Single Centre Experience

Despite the demonstrated efficacy of hydroxyurea therapy, children with sickle cell anaemia in the United Kingdom (UK) are preferentially managed with supportive care or transfusion. Hydroxyurea is reserved for children with severe disease phenotype. This is in contrast to North America and other countries where hydroxyurea is widely used for children of all clinical phenotypes. The conservative UK practice may in part be due to concerns about toxicity, in particular marrow suppression with high doses, and growth in children. We monitored 37 paediatric patients with sickle cell anaemia who were treated with hydroxyurea at a single UK treatment centre. Therapy was well tolerated and mild transient cytopenias were the only toxicity observed. Comparative analysis of patients receiving ≥26mg/kg/day versus <26 mg/kg/day demonstrates increasing dose has a significant positive effect on foetal haemoglobin (29.2% v 20.4%, p=0.0151), mean cell volume (94.4 v 86.5, p=0.0183) and reticulocyte count (99.66 x109/L v 164.3x109/L, p=0.0059). Marrow suppression was not a clinical problem with high dose treatment, haemoglobin 92.25 g/L v 91.81 g/L (ns), neutrophil count 3.3 x109/L v 4.8 x109/L (ns) and platelet count 232.4 x109/L v 302.2 x109/L (ns). Normal growth rates were maintained in all children. Good adherence to therapy was a significant factor in reducing hospitalisations This study demonstrates the effectiveness and safety in practice of high dose hydroxyurea as a disease modifying therapy which we advocate for all children with sickle cell anaemia

Information Gaps and Misinformation in the 2022 Elections

The prob­lem of elec­tion misin­form­a­tion is vast. Part of the prob­lem occurs when there is high demand for inform­a­tion about a topic, but the supply of accur­ate and reli­able inform­a­tion is inad­equate to meet that demand. The result­ing inform­a­tion gap creates oppor­tun­it­ies for misin­form­a­tion to emerge and spread.One major elec­tion inform­a­tion gap developed in 2020, when the Covid-19 pandemic drove many states to expand access to voting by mail. Inad­equate public know­ledge about the process left room for disin­form­a­tion mongers to spread false claims that mail voting would lead to wide­spread fraud. Elec­tion offi­cials could not fill inform­a­tion gaps with accur­ate inform­a­tion in time. As is now well known, no less than former Pres­id­ent Trump promoted these false claims, among others, to deny the 2020 pres­id­en­tial elec­tion results and provoke the Janu­ary 6, 2021, attack on the U.S. Capitol.In 2022, false narrat­ives about a stolen 2020 elec­tion persist, even as an unpre­ced­en­ted spate of restrict­ive voting law changes across the coun­try has created fresh inform­a­tion gaps and, thus, fresh oppor­tun­it­ies for misin­form­a­tion. Since 2020, at least 18 states have shrunk voting access, often in ways that dramat­ic­ally alter proced­ures voters might remem­ber from the past. Mean­while, lies and vitriol about the 2020 elec­tion have affected percep­tions of elec­tion admin­is­tra­tion in ways that complic­ate work to defend against misin­form­a­tion.This paper iden­ti­fies some of the most signi­fic­ant inform­a­tion gaps around elec­tions in 2022 and new devel­op­ments in elec­tions over­sight that will make it harder to guard against misin­form­a­tion. Ulti­mately, it recom­mends strategies that elec­tion offi­cials, journ­al­ists, social media compan­ies, civic groups, and indi­vidu­als can and should use to prevent misin­form­a­tion from filling gaps in public know­ledge. Lessons from other subjects, such as Covid-19 vaccine ingredi­ents and tech­no­lo­gies, show how timely responses and proact­ive "preb­unk­ing" with accur­ate inform­a­tion help to mitig­ate misin­form­a­tion