Alternative potentials for the electromagnetic field

The electromagnetic field can be expressed in terms of two complex potentials $\alpha, \beta ,$ which are related to the Debye potentials. The evolution equations for these potentials are derived, which are separable either in parabolic coordinates (leading to the radiation fields) or in radial coordinates (multipole fields). Potentials corresponding to focused wave fields as well as plane waves are discussed. A conserved radiation density can be constructed in terms of these potentials, which is positive (negative) for positive (negative) helicity radiation.Comment: 13 pages, plainTex, slightly amended version of origina

Predictive of Critical Stress and Seeking Help on Perceived Suicidal Thoughts and Attempts among Emergency Medical Service Professionals: A Content Analysis

Critical stress and seeking help among emergency medical service (EMS) professionals lead to suicidal thoughts and attempts. EMS professionals not seeking nor accepting help also adds to problems caused by critical stress. The problem is that 37% of 4,021 EMS professionals surveyed had suicidal thoughts, and 6.6% attempted suicide. Additionally, 2,300 of the 4,021 EMS professionals did not seek help for their critical stress, and nearly one-half felt no need to seek help. This study aimed to investigate the predictors of critical stress and to seek help on perceived suicidal thoughts and attempts among EMS professionals. The interpersonal theory of suicide and the person-environment fit theory were utilized. This study used a content analysis of 19 relevant studies with surveys, case studies, and interviews from the 50 United States, including the District of Columbia, Puerto Rico, American Samoa, and Guam. Data analysis included the review of descriptive findings and inferential statistical output — a review of the literature and databases on suicidal thoughts and attempts among EMS professionals. The study results indicated that critical stress and seeking help have measurable effects on suicidal thoughts and attempts among EMS providers. This study’s results might assist policymakers in positive social change by ensuring EMS organizations improve the health and well-being of their employees and increase public awareness

An Innovative Approach to Teaching Robotics

Problem Solving Using LEGOS is a 3-credit hour course offered to any student at Pace University of Pleasantville, New York. The class uses a project­ based learning environment, which consists of four design projects. This paper discusses the pedagogical advantages of teaching robotics in a mixed-reality environment with a virtual instructor as opposed to teaching robotics in a traditional laboratory setting

Heme oxygenase is induced in nephrotoxic nephritis and hemin, a stimulator of heme oxygenase synthesis, ameliorates disease

Heme oxygenase is induced in nephrotoxic nephritis and hemin, a stimulator of heme oxygenase synthesis, ameliorates disease. Heme oxygenase (HO) catalyses degradation of heme to biliverdin, iron and carbon monoxide (CO). Two isoforms exist, a constitutive form and an inducible form (HO-1). Induction of HO-1 may have protective effects in inflammation. We studied heterologous (HNTN) and accelerated (ANTN) nephrotoxic nephritis in Lewis rats. Hemin, an inducer of HO-1, (30 μmol/kg) was administered 18 hours before induction of nephritis and 72 hours later in ANTN. HO-1 was not detected immunohistochemically in normal glomeruli but was present in HNTN and ANTN in cells with the morphology of macrophages. HO-1 induction was confirmed by RT-PCR. In normal rats hemin induced glomerular HO-1 mRNA at 18 hours. In HNTN hemin markedly reduced proteinuria at 24 hours (10 ± 4 mg/24 hr; control 54 ± 16; P < 0.05), neutrophil infiltration at two hours (29.8 ± 1.8 vs. 22.3 ± 1.5 neutrophils/glomerulus, P < 0.05), and glomerular macrophage number at two hours (2.1 ± 0.1 vs. 3.1 ± 0.4 cells/glomerulus, P < 0.05). In ANTN proteinuria was reduced at day 1 and day 4 (36 ± 11 vs. 60 ± 15 and 35 ± 7 vs. 86 ± 9mg protein/24 hr, respectively, P < 0.001), glomerular thrombi were reduced by hemin at day 1 and 4 (1.5 ± 2.7 vs. 2.7 ± 0.2 and 1.3 ± 0.01 vs. 2.9 ± 0.02, respectively, P < 0.001) and glomerular macrophage infiltration was reduced on day 4 (11.2 ± 0.8 cells/glom; control 15.9 ± 0.8, P < 0.01). Possible mechanisms by which HO-1 ameliorates disease include anti-complement or anti-oxidant effects of bilirubin and vasodilator and anti-platelet effects of carbon monoxide

Passive, broadband and low-frequency suppression of laser amplitude noise to the shot-noise limit using hollow-core fibre

We use hollow-core fibre to preserve the spectrum and temporal profile of picosecond laser pulses in CBD to suppress 2.6 dB of amplitude noise at MHz noise frequencies, to within 0.01 dB of the shot-noise limit. We provide an enhanced version of the CBD scheme that concatenates circuits to suppress over multiple frequencies and over broad frequency ranges --- we perform a first demonstration that reduces total excess amplitude noise, between 2 - 6 MHz, by 85%. These demonstrations enable passive, broad-band, all-guided fibre laser technology operating at the shot-noise limit.Comment: 8 pages, 8 figure

Wild capuchin monkeys adjust stone tools according to changing nut properties

Animals foraging in their natural environments need to be proficient at recognizing and responding to changes in food targets that affect accessibility or pose a risk. Wild bearded capuchin monkeys (Sapajus libidinosus) use stone tools to access a variety of nut species, including otherwise inaccessible foods. This study tests whether wild capuchins from Serra da Capivara National Park in Brazil adjust their tool selection when processing cashew (Anacardium spp.) nuts. During the ripening process of cashew nuts, the amount of caustic defensive substance in the nut mesocarp decreases. We conducted field experiments to test whether capuchins adapt their stone hammer selection to changing properties of the target nut, using stones of different weights and two maturation stages of cashew nuts. The results show that although fresh nuts are easier to crack, capuchin monkeys used larger stone tools to open them, which may help the monkeys avoid contact with the caustic hazard in fresh nuts. We demonstrate that capuchin monkeys are actively able to distinguish between the maturation stages within one nut species, and to adapt their foraging behaviour accordingly

Hypoxia-inducible Gene Domain 1 Proteins in Yeast Mitochondria Protect Against Proton Leak Through Complex IV

Hypoxia-inducible gene domain 1 (HIGD1) proteins are small integral membrane proteins, conserved from bacteria to humans, that associate with oxidative phosphorylation supercomplexes. Using yeast as a model organism, we have shown previously that its two HIGD1 proteins, Rcf1 and Rcf2, are required for the generation and maintenance of a normal membrane potential (ΔΨ) across the inner mitochondrial membrane (IMM). We postulated that the lower ΔΨ observed in the absence of the HIGD1 proteins may be due to decreased proton pumping by complex IV (CIV) or enhanced leak of protons across the IMM. Here we measured the ΔΨ generated by complex III (CIII) to discriminate between these possibilities. First, we found that the decreased ΔΨ observed in the absence of the HIGD1 proteins cannot be due to decreased proton pumping by CIV because CIII, operating alone, also exhibited a decreased ΔΨ when HIGD1 proteins were absent. Because CIII can neither lower its pumping stoichiometry nor transfer protons completely across the IMM, this result indicates that HIGD1 protein ablation enhances proton leak across the IMM. Second, we demonstrate that this proton leak occurs through CIV because ΔΨ generation by CIII is restored when CIV is removed from the cell. Third, the proton leak appeared to take place through an inactive population of CIV that accumulates when HIGD1 proteins are absent. We conclude that HIGD1 proteins in yeast prevent CIV inactivation, likely by preventing the loss of lipids bound within the Cox3 protein of CIV