Near-field interaction between domain walls in adjacent Permalloy nanowires

The magnetostatic interaction between two oppositely charged transverse domain walls (DWs)in adjacent Permalloy nanowires is experimentally demonstrated. The dependence of the pinning strength on wire separation is investigated for distances between 13 and 125 nm, and depinning fields up to 93 Oe are measured. The results can be described fully by considering the interaction between the full complex distribution of magnetic charge within rigid, isolated DWs. This suggests the DW internal structure is not appreciably disturbed by the pinning potential, and that they remain rigid although the pinning strength is significant. This work demonstrates the possibility of non-contact DW trapping without DW perturbation and full continuous flexibility of the pinning potential type and strength. The consequence of the interaction on DW based data storage schemes is evaluated.Comment: 4 pages, 4 figures, 1 page supplimentary material (supporting.ps

Symmetries and Ambiguities in the linear sigma model with light quarks

We investigate the role of undetermined finite contributions generated by radiative corrections in a $SU(2)\times SU(2)$ linear sigma model with quarks. Although some of such terms can be absorbed in the renormalization procedure, one such contribution is left in the expression for the pion decay constant. This arbitrariness is eliminated by chiral symmetry.Comment: 9 pages. Added references through the text; an author was added due to an important contribution; corrected typos; the title also was changed. Submitted to Modern Physics Letter

Charge and mass effects on the evaporation of higher-dimensional rotating black holes

To study the dynamics of discharge of a brane black hole in TeV gravity scenarios, we obtain the approximate electromagnetic field due to the charged black hole, by solving Maxwell's equations perturbatively on the brane. In addition, arguments are given for brane metric corrections due to backreaction. We couple brane scalar and brane fermion fields with non-zero mass and charge to the background, and study the Hawking radiation process using well known low energy approximations as well as a WKB approximation in the high energy limit. We argue that contrary to common claims, the initial evaporation is not dominated by fast Schwinger discharge.Comment: Published version. Minor typos corrected. 29 pages, 5 figure

Diversidade florística e fitossociológica do tapete herbáceo da caatinga na reserva legal do Salitre, Juazeiro-BA.

Para amostragem das herbáceas foi adotado o método das parcelas, com 50m2 de área amostral em cada microhabitate

Avaliação da toxicidade da sulfametazina em organismos aquáticos.

Resumo: Dentre os fármacos, o grupo dos antibióticos, entre eles as sulfonamidas, é considerado um dos mais importantes. Estes compostos são extensivamente utilizados na medicina humana, veterinária e na aquicultura, com o propósito de prevenir ou tratar infecções microbianas. Essas substâncias podem acumular-se no solo, sofrer lixiviação ou, ainda, ser transportada via escoamento superficial para os corpos hídricos. A fim de alcançar um maior entendimento sobre os efeitos das sulfonamidas, avaliou-se a toxicidade aguda da sulfametazina utilizando-se duas espécies de invertebrados aquáticos (Daphnia similis e Artemia salina) e o peixe (Piaractus mesopotamicus). Foram determinados os valores de concentração efetiva media (CE50-48h), relacionada à imobilidade dos microcrustáceos equivalente a 77,5-48h e >1000 mg L-¹ para D. similis e A. salina, respectivamente. Para o peixe P. mesopotamicus, não houve efeito letal. Considerando-se que estes compostos são administrados em doses elevadas, a avaliação do seu impacto em toda biota aquática parece aconselhável. Os valores, portanto auxiliam para o estabelecimento de concentrações máximas permissíveis de sulfametazina nos corpos de água. Abstract: Among the drugs, the group of antibiotics, including sulfonamides, is considered one of the most important. These compounds are extensively used in human, veterinary medicine and aquaculture, with the purpose of preventing or treating microbial infections. These substances can build up in the soil, leachate or even be transported via superficial runoff to water bodies. In order to achieve a better understanding of the effects of sulfonamides, the acute toxicity of sulfamethazine was evolved using two species of aquatic invertebrates (Daphnia similis and artemia salina) and fish (Piaractus mesopotamicus). Determined the average effective concentration values were (EC50-48h), related to immobility of microcrustaceans equivalent to 77.5-48h and>1000 mg L -1 for D. similis and A. salina, respectively. For the fish P. mesopotamicus not lethal effect was found. Considering that these compounds are administered in high doses, to assess their impact on aquatic biota all seems advisable. values thus help to establish allowable maximum concentrations of sulfamethazine in water bodies

P2X7 receptor isoform B is a key drug resistance mediator for neuroblastoma

Drug resistance is a major challenge for all oncological treatments that involve the use of cytotoxic agents. Recent therapeutic alternatives cannot circumvent the ability of cancer cells to adapt or alter the natural selection of resistant cells, so the problem persists. In neuroblastoma, recurrence can occur in up to 50% of high-risk patients. Therefore, the identification of novel therapeutic targets capable of modulating survival or death following classical antitumor interventions is crucial to address this problem. In this study, we investigated the role of the P2X7 receptor in chemoresistance. Here, we elucidated the contributions of P2X7 receptor A and B isoforms to neuroblastoma chemoresistance, demonstrating that the B isoform favors resistance through a combination of mechanisms involving drug efflux via MRP-type transporters, resistance to retinoids, retaining cells in a stem-like phenotype, suppression of autophagy, and EMT induction, while the A isoform has opposite and complementary roles

Regularization Independent Analysis of the Origin of Two Loop Contributions to N=1 Super Yang-Mills Beta Function

We present a both ultraviolet and infrared regularization independent analysis in a symmetry preserving framework for the N=1 Super Yang-Mills beta function to two loop order. We show explicitly that off-shell infrared divergences as well as the overall two loop ultraviolet divergence cancel out whilst the beta function receives contributions of infrared modes.Comment: 7 pages, 2 figures, typos correcte

Effects of the rainy season on growth of Mimosa tenuiflora in dry tropical forest, Brazil.

Resumo

Evidence of random magnetic anisotropy in ferrihydrite nanoparticles based on analysis of statistical distributions

We show that the magnetic anisotropy energy of antiferromagnetic ferrihydrite depends on the square root of the nanoparticles volume, using a method based on the analysis of statistical distributions. The size distribution was obtained by transmission electron microscopy, and the anisotropy energy distributions were obtained from ac magnetic susceptibility and magnetic relaxation. The square root dependence corresponds to random local anisotropy, whose average is given by its variance, and can be understood in terms of the recently proposed single phase homogeneous structure of ferrihydrite.Comment: 6 pages, 2 figure