Search

Public health crises require individuals, often volunteers, to help minimize disasters. The COVID-19 pandemic required such activation of individuals, but little is known about medical students' preferences of such engagement. We investigated potential variations in medical students' educational preferences, attitudes, and volunteerism during the COVID-19 pandemic based on socio-demographics to better prepare for future activation scenarios. A web-based, anonymous survey of U.S. medical students at a single institution was conducted in May 2020. Across four training year, 518 (68% response rate) students completed the survey. During the pandemic, 42.3% (n = 215) wanted to discontinue in-person clinical experiences, 32.3% (n = 164) wanted to continue, and 25.4% (n = 129) were neutral. There was no gender effect for engagement in volunteer activities or preference to engage in clinical activities during the pandemic. However, second-year (n = 59, 11.6%) and third-year students (n = 58, 11.4%) wanted to continue in-person clinical experiences at a greater proportion than expected, while a small proportion of fourth-year students (n = 17, 3.3%) wanted to continue, χ2(6) = 43.48, p <.001, φ = 0.29. Majority of respondents (n = 287, 55.5%) volunteered in clinical and non-clinical settings. A lower proportion of fourth-year (n = 12, 2.3%) and first-year students (n = 50, 9.7%) volunteered than expected. Likelihood to volunteer during a pandemic varied by gender, training year, and/or prior experience with disaster event depending on the type of volunteer-site setting. Our findings suggest socio-demographic factors may impact medical student engagement and volunteerism during a public health crisis. Educational leadership should be sensitive to such variations and can facilitate volunteer activities that allow student engagement during future pandemics. [ABSTRACT FROM AUTHOR]

Quantum graphs are commonly used as models of complex quantum systems, for example molecules, networks of wires and states of condensed matter. We consider quantum statistics for indistinguishable spinless particles on a graph, concentrating on the simplest case of Abelian statistics for two particles. In spite of the fact that graphs are locally one dimensional, anyon statistics emerge in a generalized form. A given graph may support a family of independent anyon phases associated with topologically inequivalent exchange processes. In addition, for sufficiently complex graphs, there appear new discrete-valued phases. Our analysis is simplified by considering combinatorial rather than metric graphs—equivalently, a many-particle tight-binding model. The results demonstrate that graphs provide an arena in which to study new manifestations of quantum statistics. Possible applications include topological quantum computing, topological insulators, the fractional quantum Hall effect, superconductivity and molecular physics. [ABSTRACT FROM AUTHOR]

Abstract   Background Small bowel mass lesions (SBML) are a relatively common cause of obscure gastrointestinal bleeding (OGIB). Their detection has been limited by the inability to endoscopically examine the entire small intestine. This has changed with the introduction of capsule endoscopy (CE) and double balloon enteroscopy (DBE) into clinical practice. Study Aim To evaluate the detection of SBML by DBE and CE in patients with OGIB who were found to have SBML by DBE and underwent both procedures. Methods A retrospective review of a prospectively collected database of all patients undergoing DBE for OGIB at seven North American tertiary centers was performed. Those patients who were found to have SBML as a cause of their OGIB were further analyzed. Results During an 18 month period, 183 patients underwent DBE for OGIB. A small bowel mass lesion was identified in 18 patients. Of these, 15 patients had prior CE. Capsule endoscopy identified the mass lesion in five patients; fresh luminal blood with no underlying lesion in seven patients, and non-specific erythema in three patients. Capsule endoscopy failed to identify all four cases of primary small bowel adenocarcinoma. Conclusions Double balloon enteroscopy detects small bowel mass lesions responsible for OGIB that are missed by CE. Additional endoscopic evaluation of the small bowel by DBE or intraoperative enteroscopy should be performed in patients with ongoing OGIB and negative or non-specific findings on CE. [ABSTRACT FROM AUTHOR]

Abstract   Objective To review all cases of drug-induced liver injury (DILI) requiring hospitalization at a single tertiary care center. Methods Patient records were identified by ICD-9 codes for inpatient visits from November 1998 through March 2006. Results Of a total 83,265 hospital admissions during the study period, 40 were for DILI (0.048%). Thirteen patients had non-acetaminophen DILI (NA-DILI); 27 had acetaminophen-related DILI (A-DILI). In the NA-DILI group, mean age was 59 ± 17.9 years and liver injury was classified as hepatocellular (7), cholestatic (5), or mixed (1). A variety of medications were implicated with antimicrobials being the most common class. Resolution occurred in seven, two died of complications related to hepatotoxicity, one underwent liver transplantation, and the outcome was undetermined in three who were lost to follow-up. In the A-DILI group, mean age was 35 ± 11.0 years. Eighteen involved intentional overdose of acetaminophen; nine were associated with chronic use. The pattern of injury was hepatocellular in all. Resolution occurred in 4 patients, death in 8, and improvement in 15. Conclusions DILI is a rare cause of inpatient admission but is associated with significant mortality. Spontaneous resolution occurs in most patients but return to normal liver function may take months. Antimicrobial agents account for the largest proportion of NA-DILI. [ABSTRACT FROM AUTHOR]

Abstract  Isoamyl acetate, produced via fermentation, is a natural flavor chemical with applications in the food industry. Two alcohol acetyltransferases from Saccharomyces cerevisiae (ATF1 and ATF2) can catalyze the esterification of isoamyl alcohol with acetyl coenzyme A. The respective genes were cloned and expressed in an appropriate ack-pta − strain of Escherichia coli. The engineered strains produce isoamyl acetate when isoamyl alcohol is added to the culture medium. Aerobic shake flask experiments examined isoamyl acetate production over various growth times, temperatures, and initial optical densities. The strain carrying the pBAD-ATF1 plasmid exhibited a high molar ester yield from glucose (1.13) after 48 h of aerobic growth at 25 °C. Low-cost media components, such as fusel oil, sorghum glucose and corn steep liquor, were found to give a high yield of isoamyl acetate. High-cell-density gave an increased isoamyl acetate yield of 0.18 g/g of glucose consumed. [ABSTRACT FROM AUTHOR]

The current study employs hybrid-exchange density functional theory to investigate the adsorption of HF and HCl to under-coordinated Al ions on the β-AlF3 (100) surface. It is shown that the geometries of the adsorbates are strongly dependent on coverage. Furthermore, the adsorption of HCl leads to a number of distinct structures that have very similar energies. It is proposed that this result may explain the high catalytic activity of aluminium fluoride and aluminium chloro-fluoride surfaces towards chlorine–fluorine exchange reactions. The stretching and bending frequencies of the H–F and H–Cl bonds at half and full monolayer coverage are also calculated and the vibrational spectrum is found to be strongly dependent on the adsorption site and the coverage. The vibrational frequency shifts provide, therefore, a mechanism for experimentally characterising these surfaces. [ABSTRACT FROM AUTHOR]

We describe a new class of scattering matrices for quantum graphs in which back-scattering is prohibited. We discuss some properties of quantum graphs with these scattering matrices and explain the advantages and interest in their study. We also provide two methods to build the vertex scattering matrices needed for their construction. [ABSTRACT FROM AUTHOR]

Abstract   We study numerically statistical properties of the random mean square separation, Δ(t)=〈Δ2〉1/2 of fluid particle pairs in the Onsager’s point vortex gas, i.e. in a random, inviscid, two-dimensional flow generated by the motion of quantized point vortices of random polarities. This model is perhaps the simplest, two-dimensional model of superfluid turbulence in helium II at low temperatures when the normal fluid is absent. The existence of the inverse energy cascade through scales in such a system was discovered in the pioneering work by Onsager (Nuovo Cimento Suppl. 6:279, 1949). We found that the mean diffusivity of particle pairs, d〈Δ2〉/dt obeys, to a good degree of accuracy, the Richardson’s diffusion ‘four-third’ law, d〈Δ2〉/dt∼Δ4/3. We also analyzed the details of time evolution of the rms particle separation. At small time the particle separation is ballistic, while at large time, when the motion of individual particles in the considered pair becomes uncorrelated, the mean square separation follows the diffusion law, 〈Δ2〉∼t. For intermediate time we found that the root mean square separation, Δ=〈Δ2〉1/2 is very sensitive to the initial separation, due to the memory of initial separation kept by the particle pair during the initial period of exponential ballistic separation, so that the rms separation never follows the Richardson’s t 3/2 scaling law. We characterized the time evolution of the rms particle separation in the vicinity of the inflexion point of the curve Δ(t) by the power law, , and found the dependence of α and γ on the initial separation Δ0, thus generalizing the Richardson’s t 3/2-law for the considered two-dimensional point vortex gas. [ABSTRACT FROM AUTHOR]

In this paper, a comparison of modelled and observed surface wind and temperature for two campaigns of the PUMA (Pollution of Urban Midlands Atmosphere) project is presented. The Regional Atmospheric Modelling System (RAMS) was configured for the West Midlands conurbation (WM), UK, to have two nested grids with a mesh size of 2 km for the inner grid which is embedded in the outer grid with a mesh size of 8 km. Statistical evaluation of the model results against observational data of wind speed, direction and temperature was conducted. In general, the model's performance is better in the summer campaign than in the winter campaign. The results suggest that the quality of the prediction is sensitive to whether or not cloud cover is captured by the model under winter conditions. Although the topography of the region is relatively flat, some spatial patterns of wind and temperature may exist under stagnant conditions during the summer and winter seasons. Under summer conditions, the spatial patterns are associated with convective eddies or rolls during daytime, while under winter conditions, the spatial patterns are closely linked to stability and topography. The modelled results of such winter conditions for the inner grid reveal subtle spatial patterns at a scale smaller than 10 km near hills and valleys with differences in elevation of a few hundred metres. Copyright © 2007 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

The paper discusses the following frequently arising question on the spectral structure of periodic operators of mathematical physics (e.g., Schrödinger, Maxwell, waveguide operators, etc). Is it true that one can obtain the correct spectrum by using the values of the quasimomentum running over the boundary of the (reduced) Brillouin zone only, rather than the whole zone? Or, do the edges of the spectrum occur necessarily at the set of 'corner' high symmetry points? This is known to be true in 1D, while no apparent reasons exist for this to be happening in higher dimensions. In many practical cases, though, this appears to be correct, which sometimes leads to the claims that this is always true. There seems to be no definite answer in the literature, and one encounters different opinions about this problem in the community. In this paper, starting with simple discrete graph operators, we construct a variety of convincing multiply-periodic examples showing that the spectral edges might occur deeply inside the Brillouin zone. On the other hand, it is also shown that in a 'generic' case, the situation of spectral edges appearing at high symmetry points is stable under small perturbations. This explains to some degree why in many (maybe even most) practical cases the statement still holds. [ABSTRACT FROM AUTHOR]

Up to 10% of patients who undergo ileal conduit urinary diversion may go on to develop ureteroileal anastomotic stenosis (UIAS); this can lead to recurrent urinary tract infections and deterioration in renal function. Classical management has been open revision of the anastomosis. We describe a novel technique that allows balloon dilatation and ureteral stent placement in a retrograde fashion. All patients in this study had undergone radical cystectomy and ileal conduit formation with Wallace type end-to-end refluxing uretero-intestinal anastomosis. After initial retrograde loopogram, a 6F MPA-1 catheter and an 0.035 inch extra stiff guide was passed to the distal ostium. Subsequently, a customised 8F bright tip MPA-1 guiding catheter was advanced over the guide wire which allowed effective splinting of the equipment to facilitate greater control of a second catheter and guide wire combination to access the stenotic or occluded anastomosis. Results show that a total of ten anastomoses were treated; nine anastomoses were successfully treated with a primary retrograde approach with no intra or post-procedural complications. After a mean follow-up of 19 months (5-33 months), as assessed by ascending loopograms, all anastomoses remained open. In conclusion, morbidity of open surgery has resulted in the popularization of endourological techniques in treating anastomotic stenoses. However, key to these endourological techniques is access to the anastomosis; typically, this has been via a percutaneously placed nephrostomy. The ideal route to the anastomosis is via a retrograde approach; we have illustrated a safe and successful novel technique that utilized two guidewires and a guiding catheter, allowing retrograde ureteral access. [ABSTRACT FROM AUTHOR]

Abstract  Model for Endstage Liver Disease (MELD) score has been used to allocate organs since February 2002. This policy allocates organs to candidates with regard to severity of their underlying liver disease except in the case of hepatocellular carcinoma (HCC) patients. The purpose of this study was to determine the impact of MELD on waiting times, dropout rates, and transplantation rates in all patients awaiting liver transplantation at our center. The records of all patients listed for liver transplantation between May 28, 1999, and February 27, 2004, at the Mayo Clinic, Scottsdale, Arizona, were reviewed. Candidates were grouped by two time periods as pre-MELD or post-MELD based on date of MELD implementation (February 27, 2002). The incidence of deceased donor liver transplantation (DDLT), waiting time to DDLT, dropout rate from the waiting list because of clinical deterioration or death, and survival while waiting for or after DDLT were determined for each group. Three hundred fifty-one patients were listed for liver transplantation (195 pre-MELD, 156 post-MELD) during the study period. HCC patients had an improved rate of transplantation after MELD (pre-MELD, 1.39 persons per year; post-MELD, 3.48 persons per year). In all groups, with the exception of hepatitis C virus, the transplantation rates were the same for both categories. The hepatitis C virus group also had improved transplantation rates in the post-MELD period. HCC candidates under the new allocation policy have an increased incidence of DDLT in our institution. However, this has not disadvantaged patients with non-HCC diagnoses. Thus, the new MELD-based allocation policy has benefited all candidates by allowing more timely transplants. [ABSTRACT FROM AUTHOR]

In addition to the therapeutic exposure, a course of radiotherapy will involve the additional (concomitant) irradiation of the patient using CT, simulator or portal imaging systems, for localization of the target volume and subsequent verification of treatment delivery. The number of concomitant exposures is likely to increase as the developing technical capabilities for conformal, image-guided radiotherapy make target and critical organ definition an increasingly important aspect of radiotherapy. Estimation of doses and risks to critical organs in the body from all sources is thus necessary to provide the basis for adequate justification of the exposures as required by ICRP. In this paper, doses to selected organs and tissues for which ICRP have identified fatal cancer probabilities have been measured using a realistic anthropomorphic phantom loaded with thermoluminescent dosemeters and irradiated using a treatment protocol for radical radiotherapy of the prostate. Independently, doses to the same organs and tissues have been measured from concomitant CT and portal imaging exposures given for localization and verification purposes. Although negligible in comparison with the target dose, realistic numbers of concomitant exposures give a small but significant contribution to the total dose to most organs and tissues outside the target volume. Generally, this is in the range 5-10% of the total organ dose, but can be as high as 20% for bone surfaces. These data may be used to estimate concomitant doses from any combination of CT and portal imaging and may help in the justification process, especially when additional verification exposures may be required during treatment. [ABSTRACT FROM AUTHOR]

Objective: To measure the inflammatory and autonomic responses of healthy humans and patients with coronary artery disease to controlled concentrations of two specific components of vehicle derived air pollution, carbon particles and sulphur dioxide (SO2). Methods: Placebo controlled, double blind, random order human challenge study examining the effects of carbon particles (50 μg/m³) and SO2 (200 parts per billion (ppb)) on heart rate variability (HRV) and circulating markers of inflammation and coagulation in healthy volunteers and patients with stable angina. Results: In healthy volunteers, markers of cardiac vagal control did not fall in response to particle exposure but, compared with the response to air, increased transiently immediately after exposure (root mean square of successive RR interval differences (RMSSD) 15 (5) ms with carbon particles and 4 (3) ms) with air, p < 0.05). SO2 exposure resulted in no immediate change but a significant reduction in HRV markers of cardiac vagal control at four hours (RMSSD -2 (3.6) ms with air, -7 (2.7) ms with SO2, p < 0.05). No such changes were seen in patients with stable angina. Neither pollutant caused any change in markers of inflammation or coagulation at zero, four, or 24 hours. Conclusion: In healthy volunteers, short term exposure to pure carbon particles does not cause adverse effects on HRV or a systemic inflammatory response. The adverse effects of vehicle derived particulates are likely to be caused by more reactive species found on the particle surface. SO2 exposure does, however, reduce cardiac vagal control, a response that would be expected to increase susceptibility to ventricular arrhythmia. [ABSTRACT FROM AUTHOR]

As of November 2005, there were 6.2 million broadband customers in the UK and this figure is still growing. North and South America had approximately 49 million broadband users, Asia-Pacific 74 million and Europe 53 million. In the last two years, broadband has turned from a niche product into a truly mass-market product. [ABSTRACT FROM AUTHOR]

Consumer broadband has reached mass-market adoption. Over the next few years we will see a range of new entertainment, voice and other services being delivered to a variety of networked devices in increasingly complex home networks. For a service provider such as BT, this growth in market size and complexity presents both a challenge and an opportunity for customer service. The challenge is to minimise the cost of supporting these home environments. The opportunity is in being able to differentiate on service quality and generate additional revenues by managing the home network and the delivery of new services for the consumer. In this paper we will examine what management means for the home network. We will discuss the standards that exist or are emerging and discuss some approaches to management and diagnostics. [ABSTRACT FROM AUTHOR]

Total (as opposed to culturable) bacterial number counts are reported for four sites in the United Kingdom measured during campaigns over four separate seasons. These are interpreted in relation to simple climatic factors, i.e. temperature, wind speed and wind direction. Temperature has a marked effect at all four sites with data for a rural coastal site conforming best to a simple exponential model. Data for the other rural and urban locations show a baseline similar to that determined at the coastal rural location, but with some very significant positive excursions. The temperature dependence of bacterial number is found to conform to that typical of bacterial growth rates. At the coastal rural location, bacterial numbers normalised for temperature show no dependence on wind speed whilst at the inland sites there is a decrease with increasing wind speed of the form expected for a large area source. Only one site appeared to show a systematic relationship of bacterial concentrations to wind direction that being a site in the suburbs of Birmingham with highest number concentrations observed on a wind sector approaching from the city centre. PCR techniques have been used to identify predominant types of bacteria and results are presented which show that Bacillus was the dominant genus observed at the three inland sites during the winter and summer seasons. Pseudomonas appeared with comparable frequency at certain sites and seasons. There was in general a greater diversity of bacteria at the coastal site than at the inland sites. [ABSTRACT FROM AUTHOR]

Tight junctions govern the paracellular permeability of endothelial and epithelial cells. Aberrations of tight junction function are an early and key event during the vascular spread of cancer and inflammation. This study sought to determine the role of estrogen in the regulation of tight junctions and expression of molecules making tight junctions in endothelial cells. Human endothelial cell, HECV, which express ER-β but not ER-α was used. 17-β-estradiol induced a concentration- and time-dependent biphasic effect on tight junction. At 10-9 and 10-6 M, it decreased the level of occludin and increased in paracellular permeability of HECV cells, but at 10-12 M it decreased in paracellular permeability and increased the level of occludin. The transendothelial electrical resistance (TER), however, was reduced by 17-β-estradiol at lower concentrations (as low as 10-12 M). Furthermore, the time-dependent biphasic effect was observed over a period of 4 days, with the first reduction of TER seen within 15 min and the second drop occurring 48 h after 17-β-estradiol treatment. It was further revealed that protein and mRNA levels of occludin, but not claudin-1 and -5, and ZO-1, were reduced by 17-β-estradiol, in line with changes of TER. This study shows that 17-β-estradiol can induce concentration- and time-related biphasic effects on tight junction functions expression of occludin in endothelial cells and that this perturbation of tight junction functions may have implications in the etiology of mastalgia and the vascular spread of breast cancer. J. Cell. Physiol. 196: 362–369, 2003. © 2003 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

As part of the timed breeding colony at Tulane National Primate Research Center, exogenous progesterone administration (5 mg/day for 10 days) has been used to select conception dates by inducing artificial luteal phases in female rhesus monkeys. A retrospective analysis of data obtained during four breeding seasons (1998–2001) revealed that conceptions occurred an average of 18 days after the last administration of progesterone. The age of the female to be bred, previous pregnancy history, and timing of breeding during the breeding season were determined to be critical factors in the success of the procedure. The benefit of this method of timed breeding is that it does not require tracking of menstrual cycles, which can be labor-intensive and requires that animals be monitored several months in advance of breeding to determine each female's individual cycle length. It also provided an efficient use of breeding-age males. Am. J. Primatol. 60:23–28, 2003. © 2003 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Purpose: We tested a prototype stimulator interfaced with a commercially available scanning laser ophthalmoscope designed to measure retinal capillary perfusion (Heidelberg Retina Flowmeter (HRF)). The add-on stimulator optically superimposed the image of a monitor display on to the subject's retina coaxially with the imaging optics of the HRF. The purpose of the study was to determine if flicker and pattern stimulation presented in this manner could evoke changes in retinal perfusion that could be measured by the HRF. Methods: The prototype stimulator projected 55° visual angle circular fields of homogeneous flicker, alternating checkerboard, and multi-focal m-sequence hexagonal patterns on the retina of 10 human subjects during acquisition of images by the HRF. Results: Images were successfully acquired and processed. HRF perfusion values during flicker and pattern stimulation were not significantly different from control values. Conclusions: Results of the present study and a previously published study showing a flicker-induced increase in the HRF perfusion values are contradictory. Retinal perfusion measured by the HRF were not affected by flicker and pattern stimulation delivered through the prototype device. These data are not consistent with a large flicker or pattern induced increase in retinal perfusion. The instrumental modification appears promising. However, the raster scan stimulation technique or some other aspect of stimulation or image acquisition may account for the different results in the present study and previous studies in our laboratory and in the laboratories of other investigators. [ABSTRACT FROM AUTHOR]

In the article by Winograd et al., 10,927 cases of pediatric guanfacine exposures were reported to the National Poison Data System (NPDS) between 2000-2016, of which 4662 (42.7%) were in the 0-5 year age group [[1]]. While these results are limited by the relatively low number of cases, of the 4662 cases analyzed by Winograd et al. there was no effect ( I n i = 2359, 50.6%) or minor effect ( I n i = 1417, 30.4%) in the majority of cases. To the Editor, We recently reviewed the article by Winograd et al. [[1]] that focused on pediatric exposures to guanfacine. [Extracted from the article]