A search on Dirac equation

The solutions, in terms of orthogonal polynomials, of Dirac equation with analytically solvable potentials are investigated within a novel formalism by transforming the relativistic equation into a Schrodinger like one. Earlier results are discussed in a unified framework and certain solutions of a large class of potentials are given.Comment: 9 page

Technical efficiency and environmental impact of seabream and seabass farms

Sea cage farming of seabream and seabass is the most important form of aquaculture production in the Mediterranean Sea. Despite the continuous global growth in aquaculture production and demand, the economic performance of seabream and seabass companies has not followed the same trend. In recent years, companies have faced successive periods of market instability, with high volatility in supply and market prices that have strongly affected their operational margins. Despite the regional importance of this industry, only a handful of studies have examined the economic performance of these farms. In this paper, we investigate the technical efficiency and scale effects of Mediterranean aquaculture farms. Furthermore, environmental impact in terms of nutrient emissions from the farms is examined and discussed. Technical efficiency effects are analyzed using Data Envelopment Analysis (DEA), and the bootstrap procedure is used for bias correction. The results show that the mean technical efficiency could be improved by between 16% and 34%, and scale efficiency suggests that farms could improve their efficiency by operating at an optimal scale. Compared to measurements in previous studies, the environmental variables show that the emission of nutrients from the farms per kilo of fish produced has not changed over the past twenty years. Finally, policy implications suggest that more attention toward improving technical efficiency may help improve the robustness of the sector and that environmental regulation might be needed in order to improve the environmental performance of farms

Persistent Transport Barrier on the West Florida Shelf

Analysis of drifter trajectories in the Gulf of Mexico has revealed the existence of a region on the southern portion of the West Florida Shelf (WFS) that is not visited by drifters that are released outside of the region. This so-called ``forbidden zone'' (FZ) suggests the existence of a persistent cross-shelf transport barrier on the southern portion of the WFS. In this letter a year-long record of surface currents produced by a Hybrid-Coordinate Ocean Model simulation of the WFS is used to identify Lagrangian coherent structures (LCSs), which reveal the presence of a robust and persistent cross-shelf transport barrier in approximately the same location as the boundary of the FZ. The location of the cross-shelf transport barrier undergoes a seasonal oscillation, being closer to the coast in the summer than in the winter. A month-long record of surface currents inferred from high-frequency (HF) radar measurements in a roughly 60 km $\times$ 80 km region on the WFS off Tampa Bay is also used to identify LCSs, which reveal the presence of robust transient transport barriers. While the HF-radar-derived transport barriers cannot be unambiguously linked to the boundary of the FZ, this analysis does demonstrate the feasibility of monitoring transport barriers on the WFS using a HF-radar-based measurement system. The implications of a persistent cross-shelf transport barrier on the WFS for the development of harmful algal blooms on the shoreward side of the barrier are considered.Comment: Submitted to Geophysical Research Letter

Supersymmetry and the relationship between a class of singular potentials in arbitrary dimensions

The eigenvalues of the potentials $V_{1}(r)=\frac{A_{1}}{r}+\frac{A_{2}}{r^{2}}+\frac{A_{3}}{r^{3}}+\frac{A_{4 }}{r^{4}}$ and $V_{2}(r)=B_{1}r^{2}+\frac{B_{2}}{r^{2}}+\frac{B_{3}}{r^{4}}+\frac{B_{4}}{r^ {6}}$, and of the special cases of these potentials such as the Kratzer and Goldman-Krivchenkov potentials, are obtained in N-dimensional space. The explicit dependence of these potentials in higher-dimensional space is discussed, which have not been previously covered.Comment: 13 pages article in LaTEX (uses standard article.sty). Please check "http://www1.gantep.edu.tr/~ozer" for other studies of Nuclear Physics Group at University of Gaziante

Rhinocerebral mucormycosis treated with 32 gram liposomal amphotericin B and incomplete surgery: a case report

BACKGROUND: Mucormycosis (or zygomycosis) is the term for infection caused by fungi of the order Mucorales. Mucoraceae may produce severe disease in susceptible individuals, notably patients with diabetes and leukemia. Rhinocerebral mucormycosis most commonly manifests itself in the setting of poorly controlled diabetes, especially with ketoacidosis. CASE PRESENTATION: A 31-year-old diabetic man presented to the outpatient clinic with the following signs and symptoms: headache, periorbital pain, swelling and loss of vision in the right eye. On physical examination his right eye was red and swollen. There was periorbital cellulitis and the conjunctiva was edematous. KOH preparation of purulent discharge showed broad, ribbonlike, aseptate hyphae when examined under a fluorescence microscope. Cranial MRI showed involvement of the right orbit, thrombosis in cavernous sinus and infiltrates at ethmoid and maxillary sinuses. Mucormycosis was diagnosed based on these findings. Amphotericin B (AmBisome(®); 2 mg/kg.d) was initiated after the test doses. Right orbitectomy and right partial maxillectomy were performed; the lesions in ethmoid and maxillary sinuses were removed. The duration of the liposomal amphotericin B therapy was approximately 6 months and the total dose of liposomal amphotericin B used was 32 grams. Liposomal amphotericin B therapy was stopped six months later and oral fluconazole was started. CONCLUSIONS: Although a total surgical debridement of the lesions could not be performed, it is remarkable that regression of the disease could be achieved with medical therapy alone

Effects of external nutrient sources and extreme weather events on the nutrient budget of a Southern European coastal lagoon

The seasonal and annual nitrogen (N), phosphorus (P), and carbon (C) budgets of the mesotidal Ria Formosa lagoon, southern Portugal, were estimated to reveal the main inputs and outputs, the seasonal patterns, and how they may influence the ecological functioning of the system. The effects of extreme weather events such as long-lasting strong winds causing upwelling and strong rainfall were assessed. External nutrient inputs were quantified; ocean exchange was assessed in 24-h sampling campaigns, and final calculations were made using a hydrodynamic model of the lagoon. Rain and stream inputs were the main freshwater sources to the lagoon. However, wastewater treatment plant and groundwater discharges dominated nutrient input, together accounting for 98, 96, and 88 % of total C, N, and P input, respectively. Organic matter and nutrients were continuously exported to the ocean. This pattern was reversed following extreme events, such as strong winds in early summer that caused upwelling and after a period of heavy rainfall in late autumn. A principal component analysis (PCA) revealed that ammonium and organic N and C exchange were positively associated with temperature as opposed to pH and nitrate. These variables reflected mostly the benthic lagoon metabolism, whereas particulate P exchange was correlated to Chl a, indicating that this was more related to phytoplankton dynamics. The increase of stochastic events, as expected in climate change scenarios, may have strong effects on the ecological functioning of coastal lagoons, altering the C and nutrient budgets.Portuguese Science and Technology Foundation (FCT) [POCI/MAR/58427/2004, PPCDT/MAR/58427/2004]; Portuguese Science and Technology Foundation (FCT

"Mushroom cloud": a giant left ventricular pseudoaneurysm after a myocardial infarction due to myocardial bridging – a case report

Left ventricular pseudoaneurysm is an uncommon complication after transmural myocardial infarction, occurring when a free wall rupture is contained by adhesions of the overlying pericardium preventing acute tamponade. In this report, an unusual case of a 61 year-old male with a giant apical left ventricular pseudoaneurysm after an unnoticed myocardial infarction is presented. On coronary angiogram myocardial bridging of the distal left anterior descending artery was judged to be the infarct related lesion. The echocardiographic diagnosis allowed for a timely surgical intervention which resulted in the patient's full recovery

The Cd isotope composition of atmospheric aerosols from the Tropical Atlantic Ocean

Stable isotope compositions can potentially be used to trace atmospheric Cd inputs to the surface ocean and anthropogenic Cd emissions to the atmosphere. Both of these applications may provide valuable insights into the effects of anthropogenic activities on the cycling of Cd in the environment. However, a lack of constraints for the Cd isotope compositions of atmospheric aerosols is currently hindering such studies. Here we present stable Cd isotope data for aerosols collected over the Tropical Atlantic Ocean. The samples feature variable proportions of mineral dust-derived and anthropogenic Cd, yet exhibit similar isotope compositions, thus negating the distinction of these Cd sources by using isotopic signatures in this region. Isotopic variability between these two atmospheric Cd sources may be identified in other areas, and thus warrants further investigation. Regardless, these data provide important initial constraints on the isotope composition of atmospheric Cd inputs to the ocean