Study of the radiation hardness of CsI(Tl) scintillation crystals

This paper is devoted to the study of a degradation of CsI(Tl)crystals scintillation characteristics under irradiation with gamma-quanta at the uniformly distributed absorbed dose up to 3700 rad. The sample set consisted of 25 crystals of 30 cm long having a truncated pyramid shape and 30 rectangular crystals of the same length. A large difference in the light output deterioration caused by the radiation was observed for the samples of the same shape. A substantial dependence of the average light output loss from the sample shape is seen as well. On the other hand, the crystals from the same ingot behave very similarly under irradiation

Universal quantum gates based on a pair of orthogonal cyclic states: Application to NMR systems

We propose an experimentally feasible scheme to achieve quantum computation based on a pair of orthogonal cyclic states. In this scheme, quantum gates can be implemented based on the total phase accumulated in cyclic evolutions. In particular, geometric quantum computation may be achieved by eliminating the dynamic phase accumulated in the whole evolution. Therefore, both dynamic and geometric operations for quantum computation are workable in the present theory. Physical implementation of this set of gates is designed for NMR systems. Also interestingly, we show that a set of universal geometric quantum gates in NMR systems may be realized in one cycle by simply choosing specific parameters of the external rotating magnetic fields. In addition, we demonstrate explicitly a multiloop method to remove the dynamic phase in geometric quantum gates. Our results may provide useful information for the experimental implementation of quantum logical gates.Comment: 9 pages, language revised, the publication versio

Bacterial expression of two human aryl sulfotransferases

The effect of replacing a single codon in the N-terminal of human aryl sulfotransferase (HAST) 1 and 3 with one that is more commonly found in E. coli genes was assessed. The pKK233-2 E. coli expression vector was employed and the polymerase chain reaction (PCR) was used to introduce the 5' nucleotide substitution, at the same time maintaining the fidelity of the amino acid sequence. The data indicates that this change had a minimal effect on protein production, subcellular localization or, in the case of HAST3, catalytic activity. In general, the pKK233-2 E. coli vector has been less than optimal for expressing human sulfotransferase cDNAs. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved

Sub-natural linewidth in room-temperature Rb vapor using a control laser

We demonstrate two ways of obtaining sub-natural linewidth for probe absorption through room-temperature Rb vapor. Both techniques use a control laser that drives the transition from a different ground state. The coherent drive splits the excited state into two dressed states (Autler-Townes doublet), which have asymmetric linewidths when the control laser is detuned from resonance. In the first technique, the laser has a large detuning of 1.18 GHz to reduce the linewidth to 5.1 MHz from the Doppler width of 560 MHz. In the second technique, we use a counter-propagating pump beam to eliminate the first-order Doppler effect. The unperturbed probe linewidth is about 13 MHz, which is reduced below 3 MHz (0.5 \Gamma) at a detuning of 11.5 MHz.Comment: 4 pages, 7 figure

Synthesis and super-resolution imaging performance of a refractive-index-controllable microsphere superlens

Microspheres can function as optical superlenses for nanoscale super-resolution imaging. The imaging performance is mainly affected by the size and refractive index of the microsphere. Precise control of these parameters is a challenging task but of fundamental importance to the further development of the technique. In this study, we demonstrate for the first time a nanoparticle-hybrid suspension polymerization approach to chemically synthesize high-quality microspheres (ZrO2/polystyrene) with optical properties that are highly controllable. Microspheres of different sizes (d: 2�20 μm) and refractive indexes (np: 1.590�1.685) were synthesized and their super-resolution imaging performances were evaluated and compared. Our results show that continuously increasing the refractive index of microspheres can enhance the imaging resolution and quality. A 60 nm resolution has been obtained in the wide-field imaging mode and a 50 nm resolution has been obtained in the confocal mode imaging of semiconductor chip samples. The obtained 50�60 nm resolutions have significantly gone beyond the conventional 200 nm resolution limit for visible light optical microscopes; the super-resolution mechanism has been discussed. The synthesized microsphere superlenses may find applications in many other areas as well, including nanolithography, nano-sensing, nano-diagnosis, nano-spectroscopy and ultra-high density optical data storage

Continuous-distribution puddle model for conduction in trilayer graphene

An insulator-to-metal transition is observed in trilayer graphene based on the temperature dependence of the resistance under different applied gate voltages. At small gate voltages the resistance decreases with increasing temperature due to the increase in carrier concentration resulting from thermal excitation of electron-hole pairs. At large gate voltages excitation of electron-hole pairs is suppressed, and the resistance increases with increasing temperature because of the enhanced electron-phonon scattering. We find that the simple model with overlapping conduction and valence bands, each with quadratic dispersion relations, is unsatisfactory. Instead, we conclude that impurities in the substrate that create local puddles of higher electron or hole densities are responsible for the residual conductivity at low temperatures. The best fit is obtained using a continuous distribution of puddles. From the fit the average of the electron and hole effective masses can be determined.Comment: 18 pages, 5 figure

Automated voxel-wise brain DTI analysis of fitness and aging

Diffusion Tensor Imaging (DTI) has become a widely used MR modality to investigate white matter integrity in the brain. This paper presents the application of an automated method for voxel-wise group comparisons of DTI images in a study of fitness and aging. The automated processing method consists of 3 steps: 1) preprocessing including image format converting, image quality control, eddy-current and motion artifact correction, skull stripping and tensor image estimation, 2) study-specific unbiased DTI atlas computation via diffeomorphic fluid-based and demons deformable registration and 3) voxel-wise statistical analysis via heterogeneous linear regression and a wild bootstrap technique for correcting for multiple comparisons. Our results show that this fully automated method is suitable for voxel-wise group DTI analysis. Furthermore, in older adults, the results suggest a strong link between reduced fractional anisotropy (FA) values, fitness and aging

A study of the bound states for square potential wells with position-dependent mass

A square potential well with position-dependent mass is studied for bound states. Applying appropriate matching conditions, a transcendental equation is derived for the energy eigenvalues. Numerical results are presented graphically and the variation of the energy of the bound states are calculated as a function of the well-width and mass.Comment: To appear in Phys. Lett. A (Present e-mail of A.G: [email protected]

Molecular cytogenetic aberrations in patients with multiple myeloma studied by interphase fluorescence in situ hybridization

Background: Multiple myeloma (MM) is an incurable hematological disorder characterized by the accumulation of malignant plasma cells within the bone marrow (BM). The clinical heterogeneity of MM is dictated by the cytogenetic aberrations present in the clonal plasma cells (PCs). Cytogenetic studies in MM are hampered by the hypoproliferative nature of plasma cells in MM. Therefore, fluorescence in situ hybridization (FISH) analysis combined with magnetic-activated cell sorting (MACS) is an attractive alternative for evaluation of numerical and structural chromosomal changes in MM. Methods: Interphase FISH studies with three different specific probes for the regions containing 13q14.3 (D13S319), 14q32 (IGHC/IGHV) and 1q12(CEP1 ) were performed in 48 MM patients. Interphase FISH studies with LSI IGH/CCND1, LSI IGH/FGFR3, and LSI IGH/MAF probes were used to detect t(11;14)(q13;q32), t(4;14)(p16;q32), and t(14;16)(q32;q23) in patients with 14q32 rearrangement. Results: Molecular cytogenetic aberrations were found in 40 (83.3%) of the 48 MM patients. 13 patients (27.1%) simultaneously had 13q deletion/monosomy 13 [del(13q14)], illegitimate IGH rearrangement and chromosome 1 abnormality. Del(13q14) was detected in 21 cases (43.7%), and illegitimate IGH rearrangements in 29 (60.4%) including 6 with t(11;14) and 5 with t(4;14). None of 9 patients with illegitimate IGH rearrangements and without t(11;14) or t(4;14) we detected had t(14;16) (q32;q23). 24 of the 48 MM patients (50%) had chromosome 1 abnormalities. Among 21 patients with del(13q14), 15 patients had Amp1q12;16 had IgH rearrangements. Whereas, among 27 cases without del(13q14), 8 had Amp1q12; 13 had IgH rearrangements. There was a strong association between del(13q14) and Amp1q12(c2 = 8.26, р < 0.01), and between del(13q14) and IgH rearrangement(c2 = 3.88, p < 0.05). Conclusion: 13q deletion/monosomy 13, IGH rearrangement and chromosome 1 abnormality are frequent in MM. They are not randomly distributed, but strongly interconnected. Interphase FISH technique combined with MACS using CD138-specific antibody is a highly sensitive technique at detecting molecular cytogenetic aberrations in MM.Обоснование: множественная миелома (MM) — неизлечимое гематологическое заболевание, характеризирующееся накоплением злокачественных плазматических клеток в костном мозге (КM). Клиническая гетерогенность MM определяется цитогенетическими аберрациями, присутствующими в клоне плазматических клеток (ПК). Цитогенетические исследования MM осложнены гипопролиферативными особенностями ПК. В связи с этим флуоресцентная гибридизация in situ (FISH) в комбинации с сортировкой клеток, активированных магнитными полями (MACS) представляется достойной альтернативой методам оценки точечных и структурных изменений хромосом при MM. Методы: интерфазные исследования методом FISH с использованием трех различных специфических зондов для участков, содержащих 13q14.3 (D13S319), 14q32 (IGHC/IGHV) и 1q12(CEP1), проводили у 48 больных с MM. Интерфазные исследования методом FISH с использованием зондов LSI IGH/CCND1, LSI IGH/FGFR3 и LSI IGH/MAF применяли для детекции t(11;14)(q13;q32), t(4;14)(p16;q32), и t(14;16)(q32;q23) у пациентов с перестройкой 14q32. Результаты: молекулярные цитогенетические аберрации выявляли у 40 (83,3%) из 48 больных с MM. У 13 пациентов (27,1%) одновременно определены 13q делеция/моносомия 13 [del(13q14)], аномальная перестройка IGH и аномалия хромосомы 1. Del(13q14) детектировали в 21 случае (43,7%), а аномальные перестройки IGH — в 29 (60,4%), в том числе у 6 пациентов с t(11;14) и 5 с t(4;14). Ни у одного из 9 больных с аномальными перестройками IGH и без t(11;14) или t(4;14) не выявляли транслокацию t(14;16) (q32;q23). У 24 из 48 пациентов с MM (50%) определяли аномалии хромосомы 1. В группе из 21 больных с del(13q14) в 15 случаях имелись перестройки IgH Amp1q12;16. В то же время из 27 случаев без del(13q14) у 8 содержались Amp1q12; в 13 случаях отмечали перестройки IgH. Выявлена взаимосвязь между del(13q14) и Amp1q12(χ2 = 8,26, p < 0,01) и между del(13q14) и перестройками IgH (χ2 = 3,88, p < 0,05). Выводы: 13q делецию/моносомию 13, перестройку IGH и аномалию хромосомы 1 часто отмечают при MM, причем их распределение не случайно и тесно взаимосвязано. Интерфазный анализ FISH в комбинации с MACS с использованием CD138-специфичных антител является высокочувствительным методом детекции молекулярных цитогенетических аберраций при MM

Perturbative Formulation and Non-adiabatic Corrections in Adiabatic Quantum Computing Schemes

Adiabatic limit is the presumption of the adiabatic geometric quantum computation and of the adiabatic quantum algorithm. But in reality, the variation speed of the Hamiltonian is finite. Here we develop a general formulation of adiabatic quantum computing, which accurately describes the evolution of the quantum state in a perturbative way, in which the adiabatic limit is the zeroth-order approximation. As an application of this formulation, non-adiabatic correction or error is estimated for several physical implementations of the adiabatic geometric gates. A quantum computing process consisting of many adiabatic gate operations is considered, for which the total non-adiabatic error is found to be about the sum of those of all the gates. This is a useful constraint on the computational power. The formalism is also briefly applied to the adiabatic quantum algorithm.Comment: 5 pages, revtex. some references adde