A modified Schwinger's formula for the Casimir effect

After briefly reviewing how the (proper-time) Schwinger's formula works for computing the Casimir energy in the case of "scalar electrodynamics" where the boundary conditions are dictated by two perfectly conducting parallel plates with separation "a" in the Z-axis, we propose a slightly modification in the previous approach based on an analytical continuation method. As we will see, for the case at hand our formula does not need the use of Poisson summation to get a (renormalized) finite result.Comment: 6 pages, DFTUZ/93/14 (a short version will appear in the Letters in Math. Phys.

El sentimiento relacional de género en el alumnado de Educación Secundaria Obligatoria

Esta comunicación presenta resultados empíricos sobre la preferencia relacional del alumnado en la Educación Secundaria Obligatoria. Mediante el instrumento Escala de Preferencias Relacionales de Género se indaga en las predisposiciones del alumnado a elegir o rechazar a chicos o chicas según el tipo de actividad conjunta a desarrollar. Según las elecciones o los rechazos constatados podemos conocer acerca de la presencia de los mandatos de género en las aulas escolares. La muestra se compone de 722 estudiantes (chicas y chicos = 50%) de E.S.O. de la provincia de Sevilla. El error muestral es de 3,7% con un nivel de confianza del 95,5% con la máxima varianza proporcional (p = q). Los resultados muestran algunas pautas de elección según el género, observándose que las chicas son más elegidas para compartir secretos o los chicos para practicar deporte, lo que nos permite concluir sobre la presencia en la escuela de los mandatos de género patriarcales.This paper presents empirical results on relational preference of students in secondary education. The instrument Relational Scale for Gender Preferences explores students' predispositions to choose or refuse to boys or girls under the joint activity to develop. According to the observed choices or rejections can know about the presence of gender mandates in the classroom. The sample consists of 722 students (girls and boys = 50%) of ESO in the province of Seville. The sampling error is 3.7% with a confidence level of 95.5% with maximum variance method (p = q). The results show some patterns of choice by gender, showing that girls are chosen to share secrets or the kids to play sports, allowing us to conclude about the presence in the school of patriarchal gender mandates

Stroke subtypes and their possible implication in stroke prevention drug strategies

Thrombotic strokes can affect large or small arteries in the brain. Drugs to prevent atherosclerosis complication such as thrombotic strokes, should be drugs able to prevent the accumulation of intravascular fat, reduce vascular proliferation, decrease blood pressure levels with the resulting shear stress, reduce platelet aggregation, and possibly partially or totally reverse carotid plaques. Any of the commonly used antihypertensive drugs lower the incidence of stroke, with larger reductions in BP resulting in larger reductions in risk. Experimental and clinical data suggest that reducing the activity of the renin-angiotensin aldosterone system (RAAS) may have beneficial effects beyond the lowering of blood pressure to reduce stroke incidence. In clinical trials, statins consistently reduced the risk of ischemic stroke in patients with or without CHD whereas the data on the effects of other lipid modifying drugs on stroke risk are limited. Approximately 25% of strokes are recurrent. Antiplatelet therapy is indicated for the prevention of recurrent stroke in patients with a history of noncardioembolic minor stroke or transient ischemic attack (TIA). Although clinicians may choose acetylsalicylic acid (ASA) as first-line therapy for secondary prevention, clinical guidelines and evidence from trials suggest that ASA may not be the most effective strategy. A recent review discussed results from clinical trials that have compared the efficacy of ASA monotherapy versus ASA + extended release dipyridamole in secondary stroke prevention. Therefore it is difficult to extrapolate the real benefit of pharmacological prevention strategies against atherothrombotic subtype for excellence in the TOAST classification subtype that is represented by the LAAS and also with regard to lacunar subtype as an expression of lipohyalinosis process which is a further aspect of atherosclerosis

3-(2,4-Dibromo­anilino)-2,2-dimethyl-2,3-dihydro­naphtho[1,2-b]furan-4,5-dione: a new substituted aryl­amino nor-β-lapachone derivative

The title compound, C20H15Br2NO3, shows the furan ring to adopt a half-chair conformation and the two ring systems to be approximately perpendicular [dihedral angle = 71.0 (2)°]. In the crystal structure, inter­molecular C—H⋯O contacts link the mol­ecules

The new vertical neutron beam line at the CERN n_TOF facility design and outlook on the performance

At the neutron time-of-flight facility n_TOF at CERN a new vertical beam line was constructed in 2014, in order to extend the experimental possibilities at this facility to an even wider range of challenging cross-section measurements of interest in astrophysics, nuclear technology and medical physics. The design of the beam line and the experimental hall was based on FLUKA Monte Carlo simulations, aiming at maximizing the neutron flux, reducing the beam halo and minimizing the background from neutrons interacting with the collimator or back-scattered in the beam dump. The present paper gives an overview on the design of the beam line and the relevant elements and provides an outlook on the expected performance regarding the neutron beam intensity, shape and energy resolution, as well as the neutron and photon backgrounds

Taxa de aplicação máxima anual de lodo de esgoto higienizado pelo processo de estabilização alcalina: estudo comparativo de curvas de pH de solos

Objetivou-se avaliar a taxa de aplicação máxima anual de lodo de esgoto higienizado porprocesso de estabilização alcalina prolongada (EAP) em dois solos da RegiãoMetropolitana de Curitiba (Lapa e Pinhais). Obteve-se curvas de neutralização do pH,incubando-se os solos com doses crescentes de dois dos três corretivos de acidezutilizados: dois lodos EAP (obtido em condições controladas e da estação) e um calcário.Concluiu-se que três toneladas de lodo EAP higienizado sob condições controladas foiequivalente a uma tonelada de calcário; houve interação entre lodo e tipo de solo, sendoa capacidade tampão dos solos importante para determinação da taxa de aplicaçãomáxima anual

2-(4-Methyl­phen­yl)-1H-anthraceno[1,2-d]imidazole-6,11-dione: a fluorescent chemosensor

In the title compound, C22H14N2O2, the five rings of the mol­ecule are not coplanar. There is a significant twist between the four fused rings, which have a slightly arched conformation, and the pendant aromatic ring, as seen in the dihedral angle of 13.16 (8)° between the anthraquinonic ring system and the pendant aromatic ring plane

Chemoselective oxidation of benzophenazines by m-CPBA: n-oxidation vs. oxidative cleavage

Chemoselectivity is observed when a pyran-benzo[a]phenazine and a furan-benzo[a]phenazine from beta-lapachone and nor-beta-lapachone, respectively, were submitted to oxidation by m-CPBA. The pyran phenazine furnished mainly macrolactones, while the furan one led exclusively to a phenazine N-8 oxide. To understand this difference in reactivity, we synthesized a new furan phenazine, with the reactive double bond site less hindered than that of the derivative from nor-beta-lapachone. This furan phenazine, upon oxidation with m-CPBA, furnished mainly the expected macrolactone. These experimental results, along with preliminary analysis based on mechanical molecular calculations of the ground state of the substrates, allowed us to suggest that the observed chemoselectivity has a steric oxidant approach control origin, related to the presence of the geminal methyl groups in the phenazine structure. Several of the synthesized compounds are, herein, reported for the first time