Anomalous phase shift in a twisted quantum loop

Coherent motion of electrons in a twisted quantum ring is considered to explore the effect of torsion inherent to the ring. Internal torsion of the ring composed of helical atomic configuration yields a non-trivial quantum phase shift in the electrons' eigenstates. This torsion-induced phase shift causes novel kinds of persistent current flow and an Aharonov-Bohm like conductance oscillation. The two phenomena can occur even when no magnetic flux penetrates inside the twisted ring, thus being in complete contrast with the counterparts observed in untwisted rings.Comment: 13 paes, 5 figure

Implementação eficiente de emparelhamentos bilineares sobre curvas elípticas na plataforma ARM

Monografia (graduação)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Ciência da Computação, 2013.Algoritmos de chave assimétrica são projetados para que, mesmo com o conhecimento da chave de cifração, seja inviável deduzir a chave de decifração. Esses algoritmos são também chamados de algoritmos de chave pública porque permitem que uma das chaves seja de alcance público. Este fato possibilitou a utilização de técnicas criptográ_cas em cenários inéditos como comércio eletrônico e assinaturas digitais. Em 1985, Neal Koblitz e Victor Miller propuseram independentemente a utilização de curvas elípticas na construção de sistemas criptogra_cos de chave pública. A descoberta de criptossistemas baseados em curvas elípticas produziu uma nova revolução na área de criptogra_a, porque possuem baixos requisitos para armazenamento de chaves e baixo custo computacional para execução. Além disso, a descoberta de técnicas criptográ_cas baseada em emparelhamentos bilineares sobre curvas elípticas trouxe ainda novas aplicações como sistemas baseados em identidades. No entanto, o custo computacional desses criptossistemas ainda permanece signi_cativamente maior do que os tradicionais, representando um obstáculo para sua adoção, especialmente em dispositivos com recursos limitados. Dentre esse dispositivos, os smartphones e os tablets têm obtido grande sucesso no mercado por garantir acesso a capacidades cada vez maiores de computação aliadas a mobilidade e portabilidade. Como grande parte desses dispositivos possuem processadores ARM, este trabalho tem como objetivo geral aprimorar o desempenho dos métodos de criptogra_a baseado em emparelhamento bilineares sobre curvas elípticas nos processadores ARM. _______________________________________________________________________ ABSTRACTAsymmetric key algorithms are designed so that, even with the knowledge of the encryption key, it is not feasible to deduce the decryption key. These algorithms are also called public key algorithms because they allow one of the keys to be made public. This fact made possible the use of cryptographic techniques in new scenarios such as digital signatures and electronic commerce. In 1985, Neal Koblitz and Miller Victor independently proposed the use of elliptic curves for the construction of public key cryptographic systems. The discovery of cryptosystems based on elliptic curves produced a new revolution in cryptography, because of their low requirements for key storage and low computational cost for execution. Furthermore, the discovery of cryptographic techniques based on bilinear pairings on elliptic curves brought even new applications such as identity-based systems. However, the computational cost of these cryptosystems remains signi cantly higher than the traditional ones, representing an obstacle to their adoption, especially on devices with limited resources. Among such devices, smartphones and tablets have achieved great success in the market by ensuring access to increasingly large computing capacities combined with mobility and portability. Since most of these devices run on an ARM processor, this work aims to improve the overall performance of encryption methods based on bilinear pairing on elliptic curves on ARM-based processors

Torsion-induced persistent current in a twisted quantum ring

We describe the effects of geometric torsion on the coherent motion of electrons along a thin twisted quantum ring. The geometric torsion inherent in the quantum ring triggers a quantum phase shift in the electrons' eigenstates, thereby resulting in a torsion-induced persistent current that flows along the twisted quantum ring. The physical conditions required for detecting the current flow are discussed.Comment: 9 pages, 3 figure

Flux-free conductance modulation in a helical Aharonov-Bohm interferometer

A novel conductance oscillation in a twisted quantum ring composed of a helical atomic configuration is theoretically predicted. Internal torsion of the ring is found to cause a quantum phase shift in the wavefunction that describes the electron's motion along the ring. The resulting conductance oscillation is free from magnetic flux penetrating inside the ring, which is in complete contrast with the ordinary Aharonov-Bohm effect observed in untwisted quantum rings.Comment: 10 pages, 4 figure

Curvature effects on surface electron states in ballistic nanostructures

The curvature effect on the electronic states of a deformed cylindrical conducting surface of variable diameter is theoretically investigated. The quantum confinement of electrons normal to the curved surface results in an effective potential energy that affects the electronic structures of the system at low energies. This suggests the possibility that ballistic transport of electrons in low-dimensional nanostructures can be controlled by inducing a local geometric deformation.Comment: 11 pages, 3 figure

Polysaccharides as potential antioxidative compounds for extended-release matrix tablets.

The objective of this study was to identify polysaccharides with antioxidant properties for use as potential antioxidative compounds for extended-release matrix tablets. The antioxidant properties of five different polysaccharides, high molecular weight alginate (H-ALG), low molecular weight alginate (L-ALG), high molecular weight chitosan (H-chitosan), low molecular weight chitosan (L-chitosan), and pectic acid (PA) were examined using N-centered radicals from 1,1\u27-diphenyl-2-picrylhydrazyl (DPPH) and 2,2\u27-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and reducing power, based on their ability to reduce Cu(2+). L-chitosan and PA had acceptable scavenging abilities and were good radical scavengers, with good reducing power, but the H-chitosan and alginate derivatives were much less effective. The results suggest that L-chitosan and PA could be useful in combating oxidative stress. A PA and L-chitosan interpolymer complex (IPC) tablet was prepared and evaluated as an extended-release tablet matrix using theophylline (TPH) as a model drug. The release of TPH from the matrix tablet (TPH/PA/L-chitosan=200 mg:150 mg:50 mg) was slower than that from PA only (TPH/PA/chitosans=200 mg:200 mg:0 mg) or L-chitosan only (TPH/PA/L-chitosan=200 mg:0 mg:200 mg) tablet. Turbidity measurements also indicated the optimum complexation ratio for IPC between PA/L-chitosan to be 1/3, indicating an acceptable relationship between the turbidity of the complex and the release ratio of TPH. These results suggest that an L-chitosan/PA complex would be potentially useful in an extended-release IPC tablet with high antioxidant activity.The objective of this study was to identify polysaccharides with antioxidant properties for use as potential antioxidative compounds for extended-release matrix tablets. The antioxidant properties of five different polysaccharides, high molecular weight alginate (H-ALG), low molecular weight alginate (L-ALG), high molecular weight chitosan (H-chitosan), low molecular weight chitosan (L-chitosan), and pectic acid (PA) were examined using N-centered radicals from 1,1\u27-diphenyl-2-picrylhydrazyl (DPPH) and 2,2\u27-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and reducing power, based on their ability to reduce Cu(2+). L-chitosan and PA had acceptable scavenging abilities and were good radical scavengers, with good reducing power, but the H-chitosan and alginate derivatives were much less effective. The results suggest that L-chitosan and PA could be useful in combating oxidative stress. A PA and L-chitosan interpolymer complex (IPC) tablet was prepared and evaluated as an extended-release tablet matrix using theophylline (TPH) as a model drug. The release of TPH from the matrix tablet (TPH/PA/L-chitosan=200 mg:150 mg:50 mg) was slower than that from PA only (TPH/PA/chitosans=200 mg:200 mg:0 mg) or L-chitosan only (TPH/PA/L-chitosan=200 mg:0 mg:200 mg) tablet. Turbidity measurements also indicated the optimum complexation ratio for IPC between PA/L-chitosan to be 1/3, indicating an acceptable relationship between the turbidity of the complex and the release ratio of TPH. These results suggest that an L-chitosan/PA complex would be potentially useful in an extended-release IPC tablet with high antioxidant activity

Useful Extend-release Chitosan Tablets with High Antioxidant Activity.

The antioxidant properties of different low molecular weight (LMW) chitosans (CS1; 22 kDa, CS2; 38 kDa, CS3; 52 kDa, CS4; 81 kDa) were examined for possible use in extended-release tablets. The criteria used were the ability of the chitosans to reduce Cu2+, and hydroxyl and superoxide radicals and N-centered radicals derived from 1,1\u27-diphenyl-2-picrylhydrazyl, via the use of ESR spectrometry. CS2 showed the highest scavenging activity. CS1 and CS3, however, were much less effective and CS4 was not a viable antioxidant. The results suggest that CS2 could be useful in combating the development of oxidative stress. A series of chitosan tablets were prepared using a spray drying method and evaluated as an extended-release matrix tablet using theophylline (TPH) as a model drug. The release of TPH from the different MW chitosan tablets increased with increasing MW of the chitosan used. CS2, CS3 and CS4 showed a reasonable release activity, but CS1 showed the shortest release activity. Moreover, the CS2-TPH tablet showed the highest scavenging activity of the three chitosan tablets (CS2-CS4) using 2,2\u27-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) radicals. These results suggest that a CS2-TPH tablet could be potentially useful in an extended-release matrix tablet with a high antioxidant activity.The antioxidant properties of different low molecular weight (LMW) chitosans (CS1; 22 kDa, CS2; 38 kDa, CS3; 52 kDa, CS4; 81 kDa) were examined for possible use in extended-release tablets. The criteria used were the ability of the chitosans to reduce Cu2+, and hydroxyl and superoxide radicals and N-centered radicals derived from 1,1\u27-diphenyl-2-picrylhydrazyl, via the use of ESR spectrometry. CS2 showed the highest scavenging activity. CS1 and CS3, however, were much less effective and CS4 was not a viable antioxidant. The results suggest that CS2 could be useful in combating the development of oxidative stress. A series of chitosan tablets were prepared using a spray drying method and evaluated as an extended-release matrix tablet using theophylline (TPH) as a model drug. The release of TPH from the different MW chitosan tablets increased with increasing MW of the chitosan used. CS2, CS3 and CS4 showed a reasonable release activity, but CS1 showed the shortest release activity. Moreover, the CS2-TPH tablet showed the highest scavenging activity of the three chitosan tablets (CS2-CS4) using 2,2\u27-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) radicals. These results suggest that a CS2-TPH tablet could be potentially useful in an extended-release matrix tablet with a high antioxidant activity

Multiplexed Molecular Profiling of Lung Cancer Using Pleural Effusion

Introduction:Pleural effusion is frequently observed in patients with advanced lung cancer. Although effusion can be obtained less invasively and repeatedly, its use in multiplexed molecular profiling has not been fully investigated.Methods:Between July 2011 and April 2013, pleural effusion samples were obtained from patients with lung cancer at Shizuoka Cancer Center. They were analyzed for EGFR, KRAS, BRAF, PIK3CA, NRAS, MEK1, AKT1, PTEN, and HER2 mutations, EGFR, MET, FGFR1, FGFR2, and PIK3CA amplifications, and ALK, ROS1, and RET fusion genes using pyrosequensing and/or capillary electrophoresis, quantitative reverse-transcriptase polymerase chain reaction, and reverse-transcriptase polymerase chain reaction, respectively.Results:One hundred and two samples from 84 patients were analyzed. Adenocarcinoma was the most common histological subtype (82%). Genetic abnormalities were detected in 42% of patients. The most common abnormality was EGFR mutation (29%), followed by EML4-ALK rearrangement (5%), KRAS mutation, and EGFR amplification (4%, each). Concordance rates between pleural effusion and matched formalin-fixed, paraffin-embedded samples were 88%. Among 11 patients who provided samples at multiple time points, changes in molecular profile over the course of treatment were observed in five patients.Conclusions:The use of pleural effusion for multiplexed molecular testing and real-time monitoring in lung cancer was demonstrated

Embedding Effect on the Mechanical Stability of Pressurised Carbon Nanotubes

We elaborate on the cross-sectional deformation of carbon nanotubes embedded into a self-contracting host medium. The continuum elastic approach is used to formulate the mechanical energy of both the embedded nanotubes and the self-contracting outer medium with finite thickness. Our formula allows us to evaluate the critical radial pressure applied on the interface between the embedded nanotube and the outer contracting medium as well as the deformation mode that arises immediately above the critical pressure. An interesting mechanical implication of the embedding effect, that is, the power-law dependence of the critical pressure on the elastic modulus of the medium, is deduced by the theoretical approach established