Distributions of Upper PAPR and Lower PAPR of OFDM Signals in Visible Light Communications

Orthogonal frequency-division multiplexing (OFDM) in visible light communications (VLC) inherits the disadvantage of high peak-to-average power ratio (PAPR) from OFDM in radio frequency (RF) communications. The upper peak power and lower peak power of real-valued VLC-OFDM signals are both limited by the dynamic constraints of light emitting diodes (LEDs). The efficiency and transmitted electrical power are directly related with the upper PAPR (UPAPR) and lower PAPR (LPAPR) of VLC-OFDM. In this paper, we will derive the complementary cumulative distribution function (CCDF) of UPAPR and LPAPR, and investigate the joint distribution of UPAPR and LPAPR.Comment: acceptted by IEEE ICASSP 2014. arXiv admin note: text overlap with arXiv:1304.019

Numerical Approximations Using Chebyshev Polynomial Expansions

We present numerical solutions for differential equations by expanding the unknown function in terms of Chebyshev polynomials and solving a system of linear equations directly for the values of the function at the extrema (or zeros) of the Chebyshev polynomial of order N (El-gendi's method). The solutions are exact at these points, apart from round-off computer errors and the convergence of other numerical methods used in connection to solving the linear system of equations. Applications to initial value problems in time-dependent quantum field theory, and second order boundary value problems in fluid dynamics are presented.Comment: minor wording changes, some typos have been eliminate

Preparing Faculty to Incorporate Health Systems Science into the Clinical Learning Environment: Factors Associated with Sustained Outcomes

This study assesses participants’ perceptions of long-term impacts of the Teachers of Quality Academy, a medical school faculty development program designed to prepare faculty to both practice and teach health system science. A previously published 1-year evaluation of the first cohort of 27 participants showed improved perceived skills, with positive career and health system impacts. In this 5-year evaluation, a mixed-methods design included a questionnaire followed by semistructured interviews to assess perceived long-term impacts on participants. Quantitative and qualitative analyses were completed. Questionnaire response rate was 88% (N = 22), and 14 interviews were analyzed. Results demonstrated that participants had incorporated quality improvement concepts into their clinical work and teaching, better understood interprofessionalism, and observed continued improvements in care delivery. They felt the longitudinal training, delivered in a shared setting, created a learning community with lasting positive effects in institutional culture, supported long-term professional development, and had broader institutional impact. Advancements in clinical care, medical education, and professional and academic advancements were noted

Water-Soluble Mo3S4 Clusters Bearing Hydroxypropyl Diphosphine Ligands: Synthesis, Crystal Structure, Aqueous Speciation, and Kinetics of Substitution Reactions

The [Mo3S4Cl3(dhprpe)3]+ (1+) cluster cation has been prepared by reaction between Mo3S4Cl4(PPh3)3 (solvent)2 and the watersoluble 1,2-bis(bis(hydroxypropyl)phosphino)ethane (dhprpe, L) ligand. The crystal structure of [1]2[Mo6Cl14] has been determined by X-ray diffraction methods and shows the typical incomplete cuboidal structure with a capping and three bridging sulfides. The octahedral coordination around each metal center is completed with a chlorine and two phosphorus atoms of the diphosphine ligand. Depending on the pH, the hydroxo group of the functionalized diphosphine can substitute the chloride ligands and coordinate to the cluster core to give new clusters with tridentate deprotonated dhprpe ligands of formula [Mo3S4(dhprpe-H)3]+ (2+). A detailed study based on stopped-flow, 31P{1H} NMR, and electrospray ionization mass spectrometry techniques has been carried out to understand the behavior of acid−base equilibria and the kinetics of interconversion between the 1+ and the 2+ forms. Both conversion of 1+ to 2+ and its reverse process occur in a single kinetic step, so that reactions proceed at the three metal centers with statistically controlled kinetics. The values of the rate constants under different conditions are used to discuss on the mechanisms of opening and closing of the chelate rings with coordination or dissociation of chloride

Attitudes toward cost-conscious care among U.S. physicians and medical students: analysis of national cross-sectional survey data by age and stage of training

Abstract Background The success of initiatives intended to increase the value of health care depends, in part, on the degree to which cost-conscious care is endorsed by current and future physicians. This study aimed to first analyze attitudes of U.S. physicians by age and then compare the attitudes of physicians and medical students. Methods A paper survey was mailed in mid-2012 to 3897 practicing physicians randomly selected from the American Medical Association Masterfile. An electronic survey was sent in early 2015 to all 5,992 students at 10 U.S. medical schools. Survey items measured attitudes toward cost-conscious care and perceived responsibility for reducing healthcare costs. Physician responses were first compared across age groups (30–40 years, 41–50 years, 51–60 years, and > 60 years) and then compared to student responses using Chi square tests and logistic regression analyses (controlling for sex). Results A total of 2,556 physicians (65%) and 3395 students (57%) responded. Physician attitudes generally did not differ by age, but differed significantly from those of students. Specifically, students were more likely than physicians to agree that cost to society should be important in treatment decisions (p < 0.001) and that physicians should sometimes deny beneficial but costly services (p < 0.001). Students were less likely to agree that it is unfair to ask physicians to be cost-conscious while prioritizing patient welfare (p < 0.001). Compared to physicians, students assigned more responsibility for reducing healthcare costs to hospitals and health systems (p < 0.001) and less responsibility to lawyers (p < 0.001) and patients (p < 0.001). Nearly all significant differences persisted after controlling for sex and when only the youngest physicians were compared to students. Conclusions Physician attitudes toward cost-conscious care are similar across age groups. However, physician attitudes differ significantly from medical students, even among the youngest physicians most proximate to students in age. Medical student responses suggest they are more accepting of cost-conscious care than physicians and attribute more responsibility for reducing costs to organizations and systems rather than individuals. This may be due to the combined effects of generational differences, new medical school curricula, students’ relative inexperience providing cost-conscious care within complex healthcare systems, and the rapidly evolving U.S. healthcare system.https://deepblue.lib.umich.edu/bitstream/2027.42/146517/1/12909_2018_Article_1388.pd

A counterbalanced cross-over study of the effects of visual, auditory and no feedback on performance measures in a simulated cardiopulmonary resuscitation

<p>Abstract</p> <p>Background</p> <p>Previous research has demonstrated that trained rescuers have difficulties achieving and maintaining the correct depth and rate of chest compressions during both in and out of hospital cardiopulmonary resuscitation (CPR). Feedback on rate and depth mitigate decline in performance quality but not completely with the residual performance decline attributed to rescuer fatigue. The purpose of this study was to examine the effects of feedback (none, auditory only and visual only) on the quality of CPR and rescuer fatigue.</p> <p>Methods</p> <p>Fifteen female volunteers performed 10 minutes of 30:2 CPR in each of three feedback conditions: none, auditory only, and visual only. Visual feedback was displayed continuously in graphic form. Auditory feedback was error correcting and provided by a voice assisted CPR manikin. CPR quality measures were collected using SkillReporter^®software. Blood lactate (mmol/dl) and perceived exertion served as indices of fatigue. One-way and two way repeated measures analyses of variance were used with alpha set <it>a priori </it>at 0.05.</p> <p>Results</p> <p>Visual feedback yielded a greater percentage of correct compressions (78.1 ± 8.2%) than did auditory (65.4 ± 7.6%) or no feedback (44.5 ± 8.1%). Compression rate with auditory feedback (87.9 ± 0.5 compressions per minute) was less than it was with both visual and no feedback (p < 0.05). CPR performed with no feedback (39.2 ± 0.5 mm) yielded a shallower average depth of compression and a lower percentage (55 ± 8.9%) of compressions within the accepted 38-50 mm range than did auditory or visual feedback (p < 0.05). The duty cycle for auditory feedback (39.4 ± 1.6%) was less than it was with no feedback (p < 0.05). Auditory feedback produced lower lactate concentrations than did visual feedback (p < 0.05) but there were no differences in perceived exertion.</p> <p>Conclusions</p> <p>In this study feedback mitigated the negative effects of fatigue on CPR performance and visual feedback yielded better CPR performance than did no feedback or auditory feedback. The perfect confounding of sensory modality and periodicity of feedback (visual feedback provided continuously and auditory feedback provided to correct error) leaves unanswered the question of optimal form and timing of feedback.</p

Left ventricular mass increases with deteriorating glucose tolerance, especially in women: Independence of increased arterial stiffness or decreased flow-mediated dilation - The Hoorn Study

OBJECTIVE - Type 2 diabetes and impaired glucose metabolism (IGM) are associated with an increased cardiovascular disease (CVD) risk. Increased left ventricular mass (LVM) is thought to increase CVD risk through several unfavorable cardiac changes. Type 2 diabetes and IGM are associated with increased LVM, but the underlying mechanism is unclear. We investigated the association between glucose tolerance status (GTS) and LVM and explored whether any such association could be mediated through increased arterial stiffness, impaired endothelial function, or the presence of atherosclerosis. RESEARCH DESIGN AND METHODS - We used ultrasound to measure LVM, carotid and femoral stiffness, carotid-femoral transit time, and flow-mediated vasodilation (FMD) and tonometry to estimate compliance and augmentation index. The study population (n = 780) consisted of 287 individuals with normal glucose metabolism (NGM), 179 with IGM, and 314 with type 2 diabetes, and the mean age was 68.4 years. RESULTS - In women, after adjusting for age, height, BMI, and mean arterial pressure, LVM increased significantly with deteriorating GTS (LVM 157 g in NGM, 155 g in IGM, and 169 g in type 2 diabetes, P for trend <0.018). Additional adjustment for arterial stiffness, FMD, or the presence of atherosclerosis did not materially alter the results, even though these variables were significantly associated with both GTS and LVM. Indexes of hyperglycemia/-insulinemia or insulin resistance explained at most 7% of the association between GTS and LVM. In men, no statistically significant associations were observed. CONCLUSIONS - Our data expand the conceptual view of the pathogenesis of GTS-related changes in LVM because we show that the increase in LVM in women is independent of increased arterial stiffness, impaired FMD, or the presence of atherosclerosis. In addition, we show that this increase in LVM is only minimally explained by indexes of hyperglycemia/-insulinemia or insulin resistance. Our data may, in part, explain the increased CVD risk seen in women with deteriorating GTS