Plasticity in transmission strategies of the malaria parasite, Plasmodium chabaudi : environmental and genetic effects

Parasites may alter their behaviour to cope with changes in the within-host environment. In particular, investment in transmission may alter in response to the availability of parasite resources or host immune responses. However, experimental and theoretical studies have drawn conflicting conclusions regarding parasites' optimal (adaptive) responses to deterioration in habitat quality. We analyse data from acute infections with six genotypes of the rodent malaria species to quantify how investment in transmission (gametocytes) is influenced by the within-host environment. Using a minimum of modelling assumptions, we find that proportional investment in gametocytogenesis increases sharply with host anaemia and also increases at low parasite densities. Further, stronger dependence of investment on parasite density is associated with greater virulence of the parasite genotype. Our study provides a robust quantitative framework for studying parasites' responses to the host environment and whether these responses are adaptive, which is crucial for predicting the short-term and evolutionary impact of transmission-blocking treatments for parasitic diseases

On the role of the UV and X-ray radiation in driving a disk wind in X-ray binaries

X-ray heating of the photosphere of an accretion disk is a possible mechanism to produce strong, broad UV emission lines in low mass X-ray binaries (LMXBs). However, detailed photoionization calculations show that this mechanism fails to produce sufficient emission measure. We present the results of hydrodynamical calculations of the disk photosphere irradiated by strong X-rays. We attempt to determine whether LMXBs can harbor significant UV-driven disk winds despite the effects of X-ray ionization. Such winds would be a likely candidate for the site of emission of UV lines and may better explain the observations than the X-ray heated disk photosphere. We find that the local disk radiation cannot launch a wind from the disk because of strong ionizing radiation from the central object. Unphysically high X-ray opacities would be required to shield the UV emitting disk and allow the line force to drive a disk wind. However the same X-ray radiation that inhibits line driving heats the disk and can produce a hot bipolar wind or corona above the disk. To assess the impact of X-ray heating upon driving of a disk wind by the line force in any system with an accretion disk we derive analytic formulae. In particular, we compare results of line-driven disk wind models for accretion disks in LMXBs and active galactic nuclei. The latter show spectral features associated with a strong and fast disk wind. The key parameter determining the role of the line force is not merely the presence of the luminous UV zone in the disk and the presence of the X-rays, but also the distance of this UV zone from the center.Comment: LaTeX, 34 pages, contains color figures, to appear in Ap

Identifying and characterising large ramps in power output of offshore wind farms

Recently there has been a significant change in the distribution of wind farms in Great Britain with the construction of clusters of large offshore wind farms. These clusters can produce large ramping events (i.e. changes in power output) on temporal scales which are critical for managing the power system (30 minute, 60 minute and 4 hours). This study analyses generation data from the Thames Estuary cluster in conjunction with meteorological observations to determine the magnitude and frequency of ramping events and the meteorological mechanism. Over a 4 hour time window, the extreme ramping events of the Thames Estuary cluster were caused by the passage of a cyclone and associated weather fronts. On shorter time scales, the largest ramping events over 30 minute and 60 minute time windows are not associated with the passage of fronts. They are caused by three main meteorological mechanisms; (1) very high wind speeds associated with a cyclone causing turbine cut-out (2) gusts associated with thunderstorms and (3) organised band of convection following a front. Despite clustering offshore capacity, the addition of offshore wind farms has increased the mean separation between capacity and therefore reduced the variability in nationally aggregated generation on high frequency time scales

Observations of wind speed profiles over Greater London, UK, using a Doppler lidar

To calculate the potential wind loading on a tall building in an urban area, an accurate representation of the wind speed profile is required. However, due to a lack of observations, wind engineers typically estimate the characteristics of the urban boundary layer by translating the measurements from a nearby reference rural site. This study presents wind speed profile data obtained from a Doppler lidar in central London, UK, during an 8 month observation period. Used in conjunction with wind speed data measured at a nearby airport, the data have been used to assess the accuracy of the predictions made by the wind engineering tools currently available. When applied to multiple changes in surface roughness identified from morphological parameters, the non-equilibrium wind speed profile model developed by Deaves (1981) provides a good representation of the urban wind speed profile. For heights below 500 m, the predicted wind speed remains within the 95% confidence interval of the measured data. However, when the surface roughness is estimated using land use as a proxy, the model tends to overestimate the wind speed, particularly for very high wind speed periods. These results highlight the importance of a detailed assessment of the nature of the surface when estimating the wind speed above an urban surface

Resonance line-profile calculations based on hydrodynamical models of cataclysmic variable winds

We present synthetic line profiles as predicted by the models of 2-D line- driven disk winds due to Proga, Stone & Drew. We compare the model line profiles with HST observations of the cataclysmic variable IX Vel. The model wind consists of a slow outflow that is bounded on the polar side by a fast stream. We find that these two components of the wind produce distinct spectral features. The fast stream produces profiles which show features consistent with observations. These include the appearance of the P-Cygni shape for a range of inclinations, the location of the maximum depth of the absorption component at velocities less than the terminal velocity, and the transition from absorption to emission with increasing inclination. However the model profiles have too little absorption or emission equivalent width. This quantitative difference between our models and observations is not a surprise because the line-driven wind models predict a mass loss rate that is lower than the rate required by the observations. We note that the model profiles exhibit a double-humped structure near the line center which is not echoed in observations. We identify this structure with a non-negligible redshifted absorption which is formed in the slow component of the wind where the rotational velocity dominates over expansion velocity. We conclude that the next generation of disk wind models, developed for application to CVs, needs to yield stronger wind driving out to larger disk radii than do the present models.Comment: LaTeX, 19 pages, to appear in Ap

Inappropriate electrolyte repletion for patients undergoing endoscopic procedures

At Thomas Jefferson University Hospital (TJUH), there has been a perceived necessity among housestaff and fellows to routinely check and replete serum potassium and magnesium for inpatients prior to endoscopic procedures In addition, there was an unwritten policy that these electrolytes needed to be aggressively repleted, with a goal potassium above 4.0 and magnesium above 2.0 Contributing factors include absence of clear policy, fear of adverse outcomes during procedures, and fear of delay of procedures leading to increased hospital stay This practice has led to unwarranted lab draws, costs of lab tests and electrolyte riders, and possible delayed procedures Goals Clarify policies regarding electrolyte repletion Determine frequency of inappropriate electrolyte checking and repletion Determine monetary cost of this action Decrease frequency of inappropriate electrolyte lab check and repletionhttps://jdc.jefferson.edu/patientsafetyposters/1023/thumbnail.jp

A Comparison of Optimism Levels and Life Stress Levels among NCAA Division I Athletes and Non Athletes

Researchers suggest that optimistic individuals approach life situations with the belief that outcomes will be favorable, and are more likely to exhibit better coping mechanisms when dealing with adversity and stress (Carver, & Scheier, 1987; Karadeaus, Karvelis, Argyropoulou, 2007). Moreover, the cognitive adaptation theory suggests that optimistic individuals are more likely to make appropriate cognitive adaptations to stressful situations (Lightsey, 1994; Alloy & Clements, 1992). Results concerning collegiate athletic status, gender, optimism, and stress are mixed. The purpose of this study was to compare collegiate athletes and non athletes and gender on optimism and life stress. The present study utilized the Life Orientation Test-Revised to optimism and the Undergraduate Stress Questionnaire to measure life stress. Results from this study support the hypotheses that 1) high-level optimistic athletes would experience significantly lower levels of life stress than low-level optimistic athletes; 2) high-level optimistic athletes would experience significantly lower levels of life stress than high-level optimistic non-athletes; and 3) high-level optimistic men would experience significantly lower levels of life stress than high-level optimistic women within the sample Future research about optimism and stress levels, athletic status, and gender is included within the discussion

The importance of forecasting regional wind power ramping: a case study for the UK

In recent years there has been a significant change in the distribution of wind farms in Great Britain, with a trend towards very large offshore farms clustered together in zones. However, there are concerns these clusters could produce large ramping events on time scales of less than 6 hours as local meteorological phenomena simultaneously impact the production of several farms. This paper presents generation data from the wind farms in the Thames Estuary (the largest cluster in the world) for 2014 and quantifies the high frequency power ramps. Based on a case study of a ramping event which occurred on 3rd November 2014, we show that due to the large capacity of the cluster, a localised ramp can have a significant impact on the cost of balancing the power system on a national level if it is not captured by the forecast of the system operator. The planned construction of larger offshore wind zones will exacerbate this problem. Consequently, there is a need for accurate regional wind power forecasts to minimise the costs of managing the system. This study shows that state-of-the-art high resolution forecast models have capacity to provide valuable information to mitigate this impact

Distribution of LeConte\u27s Free-tailed Bat (Tadarida brasiliensis cynocephala) in Arkansas, with Notes on Reproduction and Natural History

During the past 20 years (1982-2001) we have studied the biology, occurrence and distribution of LeConte\u27s (Brazilian) free-tailed bat, Tadarida brasiliensis cynocephala, in Arkansas. Colonies and individuals were reported from man made structures only. Four new county records have been documented since 1988, extending the range from the central part of the state to Arkansas\u27s northern-most tier of counties. Numerous nuisance maternity colonies were investigated during exclusion activities and one, year-round colony provided the majority of reproductive data. A total of 152 free-tailed bats was submitted to the Arkansas Department of Health Rabies Laboratory (1982-2001); most during February through April, a period that corresponded to annual mating activity. Pregnant bats had single embryos only in the right uterine horn and parturition occurred in mid-June. Seven specimens tested positive for rabies

Constitutional Cohesion and the Right to Public Health

Despite years of significant legal improvements stemming from a renaissance in public health law, Americans still face major challenges and barriers in assuring their communal health. Reversals of legal reforms coupled with maligned policies and chronic underfunding contribute to diminished public health outcomes. Underlying preventable morbidity and mortality nationally are realities of our existing constitutional infrastructure. In essence, there is no general obligation of government to protect or promote the public’s health. Under principles of “constitutional cohesion,” structural facets and rights-based principles interwoven within the Constitution protect individuals and groups from governmental vices (i.e., oppression, overreaching, tyranny, and malfeasance). Structural impediments and rights infringements provide viable options to challenge governmental efforts inapposite to protecting the public’s health. Through corollary applications framed as auxiliary, creative, and ghost righting, courts are also empowered to recognize core duties or rights that the Constitution may not explicitly denote but assuredly contains, to remedy identifiable vices. Notably, ghost righting charts a course for recognizing a constitutional right to public health that Americans are owed, and government must respect, to assure basic public health needs