Stability of spin droplets in realistic quantum Hall devices

We study the formation and characteristics of "spin droplets",i.e., compact spin-polarized configurations in the highest occupied Landau level, in an etched quantum Hall device at filling factors $2\leq\nu\leq3$. The confining potential for electrons is obtained with self-consistent electrostatic calculations on a GaAs/AlGaAs heterostructure with experimental system parameters. Real-space spin-density-functional calculations for electrons confined in the obtained potential show the appearance of stable spin droplets at $\nu\sim 5/2$. The qualitative features of the spin droplet are similar to those in idealized (parabolic) quantum-dot systems. The universal stability of the state against geometric deformations underline the applicability of spin droplets in, e.g., spin-transport through quantum point contacts.Comment: 11 pages, 6 figure

Screening theory based modeling of the quantum Hall based quasi-particle interferometers, defined at quantum dots

In this work, we investigate the spatial distributions and the widths of the incompressible strips, i.e. the edge-states. The incompressible strips that correspond to nu = 1,2 and 1/3 filling factors are examined in the presence of a strong perpendicular magnetic field. We present a microscopic picture of the fractional quantum Hall effect based interferometers, within a phenomenological model. We adopt Laughlin quasi-particle properties in our calculation scheme. In the fractional regime, the partially occupied lowest Landau level is assumed to form an energy gap due to strong correlations. Essentially by including this energy gap to our energy spectrum, we obtain the properties of the incompressible strips at nu = 1/3. The interference conditions are investigated as a function of the gate voltage and steepness of the confinement potential, together with the strength of the applied magnetic field. (c) 2012 Elsevier B.V. All rights reserved

Study on prophylactic efficacies of daptomycin and vancomycin in a rat model of MRSA infection secondary to spinal implantation [Spinal enstrümantasyon sonrasi{dotless} MRSA enfeksiyonu oluşturulmuş rat modeli üzerinde vankomisin ve daptomisin'in profilaktik etkileri]

The present study aims to investigate the prophylactic effects of daptomycin and vancomycin in an experimental spinal infection induced by spinal implantation. The study involved inoculation of a bacterial suspension prepared with the MRSA ATCC 43300 strain to the implant bed and to the peripheral tissue immediately the implantation of titanium spinal implants to the bone in adult Winstar rats. The animals were divided into three groups; seven rats in the first group received no antibiotics, while the seven rats in group two and eight rats in group three received daptomycin and vancomycin, respectively. Microbiological and histological assessments were carried out on rats with induced infections. In the swab cultures of deep surgical areas, vancomycin demonstrated inhibition of infection of the surgical site in half of animals (50%) whereas daptomycin exhibited the same effect in more animals (71.4%), which was statistically significant compared to the control group (p0.05). As a result; comparing control group, preventive effects of daptomycin and vancomycin in infection induced model of spinal implantation with high bacteria inoculums were not found statistically significant whereas daptomycin showed statistically significant inhibition on deep surgical area infection

The role of Na+ channels in twitch generation during exposure of the frog rectus abdominis to Ca-free Ringer solution with Na(2)EDTA

WOS: A1997XJ12700001PubMed ID: 9227789The aim of the study was to investigate whether Na+ channels play a role in the twitch component of the response of the isolated frog rectus abdominis to Ca2+-free Ringer solution with 0.2 mM Na(2)EDTA by using tetrodotoxin and some other well known drugs that exhibit a blocking action on Na+ channels. In the presence of 5 X 10(-7) M tetrodotoxin, the twitch component, measured isotonically, disappeared. Although 10(-7) M d-tubocurarine was found to be ineffective, a complete blockage of twitch amplitude was observed at 5 x 10(-6) M concentration of the drug. The inhibitory action of d-tubocurarine on twitch response was not antagonized by 10(-6) and 10(-5) M carbachol. Propranolol (10(-6) - 10(-5) M), lidocaine (2 x 10(-6) - 10(-5) M), quinine (10(-6) - 2 X 10(-5) M) and quinidine (10(-6) - 2 X 10(-5) M) inhibited maximal twitch amplitude in a concentration dependent manner. These findings strongly suggest that activation of tetrodotoxin sensitive Na+ channel may play a primary role at twitch generation during exposure of the frog rectus abdominis to Ca2+-free Ringer solution with Na-2 EDTA

The role of thrombocyte activation on early brain injury in experimental subarachnoid hemorrhage model [Deneysel sak modelinde trombosit aktivasyonunun erken beyin hasari{dotless} gelişimindeki rolü]

Aim: Thrombocyte activation is one of the mechanisms blamed for emerging of early brain injury(EBI) soon after subarachnoid hemorrhage(SAH). It is wondered by researching to what extend neuron injury is prevented by making thrombocyte inhibition in SAH model. It shows that the role of trombocyte activation on EBI. Material and Method: 21 rabbits weighting 3-5 kg are divided in 3 groups 7 each. After ether anesthesia, 0.2 cc arterial blood taking from group 1 and 2 was injected into cysterna magna and created SAH. After SAH, at regular intervals antithrombocyte drug (tirofiban) was given to group 2 intraperitoneally; no treatment was carried on group 1. 0.2 cc SF was injected into cysterna magna in group 3. Decapitation was done in 72nd hour and then ischemic brain map was done at hippocampus level. The amount of ischemic neuron was scored and statistically analyzed. Results: SAH was detected in all rabbits of group 1 and 2. There are meaningful difference between the group 1 and group 3 of scoring ischemic neuron of hippocampus's CA-3 and CA-4 areas. Whereas in group 2, which is a ischemic neuron treatment group, there is a decline in each area, this decline has reached to a statistical means only in CA-4 area. Conclusion: There can be neuronal loss due to EBI even in the area which is free from blood in experimental SAH. Decreasing the injury of neuron with an antithrombocyte medicine shows that thrombocyte activation plays a great role in pathogenesis of EBI