Nondegenerate parametric down conversion in coherently prepared two-level atomic gas

We describe parametric down conversion process in a two-level atomic gas, where the atoms are in a superposition state of relevant energy levels. This superposition results in splitting of the phase matching condition into three different conditions. Another, more important, peculiarity of the system under discussion is the nonsaturability of amplification coefficients with increasing pump wave intensity, under "sideband" generation conditions

Microstructures and resistivity of cuprate/manganite bilayer deposited on SrTiO3 substrate

Thin Yba[SUB2]Cu[SUB3]O[SUB7-δ/La[SUB0.67]Ca[SUB0.33]MnO[SUB3] (YBCO/LCMO) films were grown on SrTiO[SUB3](STO)substrates by magnetron sputtering technique. The microstructures of the bilayers were characterized and a standard four-probe technique was applied to measure the resistivity of the samples. The interdiffusions at the YBCO/LCMO and LCMO/STO interfaces formed two transient layers with the thickness of about 3 and 2 nm, respectively. All the bilayers were well textured along the c axis. At low temperature, the superconductivity can only be observed when the thickness of YBCO is more than 25 nm. When the thickness of YBCO is less than 8 nm, the bilayers show only ferromagnetism. The superconductivity and ferromagnetism perhaps coexist in the bilayer with the YBCO thickness of 12.5 nm. These interesting properties are related to the interaction between spin polarized electrons in the manganites and the cooper pairs in the cuprates. © 2003 American Institute of Physics.published_or_final_versio

Design of Microwave Diagnosis and Treatment Integrated Real-Time Detection System

This project designs an integrated real-time detection system for microwave diagnosis and treatment. Non-invasive temperature estimation using microwave conformal array antenna and Nakagami distributed temperature calculation based on BP neural network can effectively assist doctors in better treatment of breast cancer patients

Autofocus for multispectral camera using focus symmetry

Author name used in this publication: Si-Jie ShaoAuthor name used in this publication: John H. Xin2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Fabrication of Densely Packed AlN Nanowires by a Chemical Conversion of Al2O3Nanowires Based on Porous Anodic Alumina Film

Porous alumina film on aluminum with gel-like pore wall was prepared by a two-step anodization of aluminum, and the corresponding gel-like porous film was etched in diluted NaOH solution to produce alumina nanowires in the form of densely packed alignment. The resultant alumina nanowires were reacted with NH3and evaporated aluminum at an elevated temperature to be converted into densely packed aluminum nitride (AlN) nanowires. The AlN nanowires have a diameter of 15–20 nm larger than that of the alumina nanowires due to the supplement of the additional evaporated aluminum. The results suggest that it might be possible to prepare other aluminum compound nanowires through similar process

Mesonia sediminis sp nov., isolated from a sea cucumber culture pond

A yellow-pigmented, Gram-stain negative and facultatively anaerobic bacterium, designated MF326(T), was isolated from a sample of sediment collected from a sea cucumber culture pond in Rongcheng, China (122A degrees 14'34aEuro(3)E 36A degrees 54'36aEuro(3)N). Cells of strain MF326(T) were found to be catalase negative and oxidase positive. Optimal growth was found to occur at 30 A degrees C and pH 7.0-7.5 in the presence of 2.0-3.0 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain MF326(T) is a member of the genus Mesonia and exhibits the high sequence similarity (94.3 %) with the type strain of Mesonia ostreae, followed by Mesonia algae (93.9 %). The dominant fatty acids of strain MF326(T) were identified as iso-C-15:0, an unidentified fatty acid with an equivalent chain-length of 13.565 and anteiso-C-15:0. The major polar lipids were found to be two unidentified lipids and phosphatidylethanolamine. The major respiratory quinone was found to be MK-6 and the genomic DNA G+C content was determined to be 40.7 mol%. On the basis of the phylogenetic analysis and differential phenotypic characteristics, it is concluded that strain MF326(T) (=KCTC 42255(T) =MCCC 1H00125(T)) should be assigned to the genus Mesonia as the type strain of a novel species, for which the name Mesonia sediminis sp. nov. is proposed.A yellow-pigmented, Gram-stain negative and facultatively anaerobic bacterium, designated MF326(T), was isolated from a sample of sediment collected from a sea cucumber culture pond in Rongcheng, China (122A degrees 14'34aEuro(3)E 36A degrees 54'36aEuro(3)N). Cells of strain MF326(T) were found to be catalase negative and oxidase positive. Optimal growth was found to occur at 30 A degrees C and pH 7.0-7.5 in the presence of 2.0-3.0 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain MF326(T) is a member of the genus Mesonia and exhibits the high sequence similarity (94.3 %) with the type strain of Mesonia ostreae, followed by Mesonia algae (93.9 %). The dominant fatty acids of strain MF326(T) were identified as iso-C-15:0, an unidentified fatty acid with an equivalent chain-length of 13.565 and anteiso-C-15:0. The major polar lipids were found to be two unidentified lipids and phosphatidylethanolamine. The major respiratory quinone was found to be MK-6 and the genomic DNA G+C content was determined to be 40.7 mol%. On the basis of the phylogenetic analysis and differential phenotypic characteristics, it is concluded that strain MF326(T) (=KCTC 42255(T) =MCCC 1H00125(T)) should be assigned to the genus Mesonia as the type strain of a novel species, for which the name Mesonia sediminis sp. nov. is proposed

Zettawatt-Exawatt Lasers and Their Applications in Ultrastrong-Field Physics: High Energy Front

Since its birth, the laser has been extraordinarily effective in the study and applications of laser-matter interaction at the atomic and molecular level and in the nonlinear optics of the bound electron. In its early life, the laser was associated with the physics of electron volts and of the chemical bond. Over the past fifteen years, however, we have seen a surge in our ability to produce high intensities, five to six orders of magnitude higher than was possible before. At these intensities, particles, electrons and protons, acquire kinetic energy in the mega-electron-volt range through interaction with intense laser fields. This opens a new age for the laser, the age of nonlinear relativistic optics coupling even with nuclear physics. We suggest a path to reach an extremely high-intensity level $10^{26-28}$W/cm$^2$ in the coming decade, much beyond the current and near future intensity regime $10^{23}$W/cm$^2$, taking advantage of the megajoule laser facilities. Such a laser at extreme high intensity could accelerate particles to frontiers of high energy, tera-electron-volt and peta-electron-volt, and would become a tool of fundamental physics encompassing particle physics, gravitational physics, nonlinear field theory, ultrahigh-pressure physics, astrophysics, and cosmology. We focus our attention on high-energy applications in particular and the possibility of merged reinforcement of high-energy physics and ultraintense laser.Comment: 25 pages. 1 figur

Natural Selection and Adaptive Evolution of Leptin in the Ochotona Family Driven by the Cold Environmental Stress

BACKGROUND: Environmental stress can accelerate the evolutionary rate of specific stress-response proteins and create new functions specialized for different environments, enhancing an organism's fitness to stressful environments. Pikas (order Lagomorpha), endemic, non-hibernating mammals in the modern Holarctic Region, live in cold regions at either high altitudes or high latitudes and have a maximum distribution of species diversification confined to the Qinghai-Tibet Plateau. Variations in energy metabolism are remarkable for them living in cold environments. Leptin, an adipocyte-derived hormone, plays important roles in energy homeostasis. METHODOLOGY/PRINCIPAL FINDINGS: To examine the extent of leptin variations within the Ochotona family, we cloned the entire coding sequence of pika leptin from 6 species in two regions (Qinghai-Tibet Plateau and Inner Mongolia steppe in China) and the leptin sequences of plateau pikas (O. curzonia) from different altitudes on Qinghai-Tibet Plateau. We carried out both DNA and amino acid sequence analyses in molecular evolution and compared modeled spatial structures. Our results show that positive selection (PS) acts on pika leptin, while nine PS sites located within the functionally significant segment 85-119 of leptin and one unique motif appeared only in pika lineages-the ATP synthase alpha and beta subunit signature site. To reveal the environmental factors affecting sequence evolution of pika leptin, relative rate test was performed in pikas from different altitudes. Stepwise multiple regression shows that temperature is significantly and negatively correlated with the rates of non-synonymous substitution (Ka) and amino acid substitution (Aa), whereas altitude does not significantly affect synonymous substitution (Ks), Ka and Aa. CONCLUSIONS/SIGNIFICANCE: Our findings support the viewpoint that adaptive evolution may occur in pika leptin, which may play important roles in pikas' ecological adaptation to extreme environmental stress. We speculate that cold, and probably not hypoxia, may be the primary environmental factor for driving adaptive evolution of pika leptin

Validation of an arterial tortuosity measure with application to hypertension collection of clinical hypertensive patients

<p>Abstract</p> <p>Background</p> <p>Hypertension may increase tortuosity or twistedness of arteries. We applied a centerline extraction algorithm and tortuosity metric to magnetic resonance angiography (MRA) brain images to quantitatively measure the tortuosity of arterial vessel centerlines. The most commonly used arterial tortuosity measure is the distance factor metric (DFM). This study tested a DFM based measurement’s ability to detect increases in arterial tortuosity of hypertensives using existing images. Existing images presented challenges such as different resolutions which may affect the tortuosity measurement, different depths of the area imaged, and different artifacts of imaging that require filtering.</p> <p>Methods</p> <p>The stability and accuracy of alternative centerline algorithms was validated in numerically generated models and test brain MRA data. Existing images were gathered from previous studies and clinical medical systems by manually reading electronic medical records to identify hypertensives and negatives. Images of different resolutions were interpolated to similar resolutions. Arterial tortuosity in MRA images was measured from a DFM curve and tested on numerically generated models as well as MRA images from two hypertensive and three negative control populations. Comparisons were made between different resolutions, different filters, hypertensives versus negatives, and different negative controls.</p> <p>Results</p> <p>In tests using numerical models of a simple helix, the measured tortuosity increased as expected with more tightly coiled helices. Interpolation reduced resolution-dependent differences in measured tortuosity. The Korean hypertensive population had significantly higher arterial tortuosity than its corresponding negative control population across multiple arteries. In addition one negative control population of different ethnicity had significantly less arterial tortuosity than the other two.</p> <p>Conclusions</p> <p>Tortuosity can be compared between images of different resolutions by interpolating from lower to higher resolutions. Use of a universal negative control was not possible in this study. The method described here detected elevated arterial tortuosity in a hypertensive population compared to the negative control population and can be used to study this relation in other populations.</p