Operation of a single mode external-cavity laser diode array near 780 nm

We have narrowed the spectral bandwidth of a commercial 2 W laser diode array to be less than 120 MHz near 780 nm. The external-cavity laser diode array system is a standard double-pass Littman–Metcalf configuration operating on a dominant single longitudinal mode. © 2002 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69845/2/RSINAK-73-12-4169-1.pd

Optimum Power Allocation for Average Power Constrained Jammers in the Presense of Non-Gaussian Noise

Cataloged from PDF version of article.We study the problem of determining the optimum power allocation policy for an average power constrained jammer operating over an arbitrary additive noise channel, where the aim is to minimize the detection probability of an instantaneously and fully adaptive receiver employing the Neyman-Pearson (NP) criterion. We show that the optimum jamming performance can be achieved via power randomization between at most two different power levels. We also provide sufficient conditions for the improvability and nonimprovability of the jamming performance via power randomization in comparison to a fixed power jamming scheme. Numerical examples are presented to illustrate theoretical results

Insulin sensitivity indices: Fasting versus glucose-stimulated ýndices in pediatric non-alcoholic fatty liver disease

OBJECTIVE: We aimed to compare insulin sensitivity indices, fasting vs glucose stimulated, in children and adolescents with non-alcoholic fatty liver disease. PATIENTS AND METHODS: Two hundredeleven obese children with median age of 11.24 ± 2.65 years were evaluated. After initial clinical and anthropometric examination, B-mode ultrasonography (USG) was performed and all subjects underwent Oral Glucose Tolerance Test (OGTT). Quantitative insulin sensitivity check index (QUICKI), homeostatic model assessment for insulin resistance (Homa-IR), the insulinogenic index (IGI), the Matsuda index, and the oral glucose insulin sensitivity (OGIS) model were used to determine peripheral insulin sensitivity. RESULTS: 59.24% (68 boys, 57 girls) of obese children had NALFD. The prevalence of FLD in obese adolescents was significantly higher than in prepubertal children (65.8% vs. 51.5%). Fasting glucose, insulin, Homa-IR, QUICKI, and OGIS and Matsuda were significantly different between subjects with and without NALFD. Insulin and glucose indices were not found to be significantly different in the prepubertal group, whereas Homa-IR, QUICKI, Matsuda, and OGIS were significantly different in the pubertal group. Age, waist circumference, and OUICKI were found to be risk factors associated with the presence of NALFD in the logistic-regression analysis. CONCLUSIONS: Age, waist circumference, and OUICKI were found to be risk factors associated with NALFD. As the value of QUICKI decreases, the probability of having steatosis increases. Although OGTT results gave the information about the glucose tolerance of a subject, indices derived from OGTT were not found to be superior to the traditional surrogates such as Homa-IR or QUICKI

Conserved Charges of Higher D Kerr-AdS Spacetimes

We compute the energy and angular momenta of recent D-dimensional Kerr-AdS solutions to cosmological Einstein gravity, as well as of the BTZ metric, using our invariant charge definitions.Comment: 11 pages, references added, equation correcte

All unitary cubic curvature gravities in D dimensions

We construct all the unitary cubic curvature gravity theories built on the contractions of the Riemann tensor in D -dimensional (anti)-de Sitter spacetimes. Our construction is based on finding the equivalent quadratic action for the general cubic curvature theory and imposing ghost and tachyon freedom, which greatly simplifies the highly complicated problem of finding the propagator of cubic curvature theories in constant curvature backgrounds. To carry out the procedure we have also classified all the unitary quadratic models. We use our general results to study the recently found cubic curvature theories using different techniques and the string generated cubic curvature gravity model. We also study the scattering in critical gravity and give its cubic curvature extensions.Comment: 24 pages, 1 figure, v2: A subsection on cubic curvature extensions of critical gravity is added, v3: The part regarding critical gravity is revised. Version to appear in Class. Quant. Gra

Effect of different segmentation methods using optical satellite imagery to estimate fuzzy clustering parameters for Sentinel-1A SAR images

Optical and SAR data are efficient data sources for shoreline monitoring. The processing of SAR data such as feature extraction is not an easy task since the images have totally different structure than optical imagery. Determination of threshold value is a challenging task for SAR data. In this study, SENTINEL-2A optical data was used as ancillary data to predict fuzzy membership parameters for segmentation of SENTINEL-1A SAR data to extract shoreline. SENTINEL-2A and SENTINEL-1A satellite images used were taken in September 9, 2016 and September 13, 2016 respectively. Three different segmentation algorithms which are selected from object, learning and pixel-based methods. They have been exploited to obtain land and water classes which have been used as an input data for parameter estimation. Thus, the performance of different segmentation algorithm has been investigated and analysed. In the first step of the study, Mean-Shift, Random Forest and Whale Optimization algorithms have been employed to obtain water and land classes from the SENTINEL-2A image. Water and land classes derived from each algorithm – are used as input data, and then the required parameters for the fuzzy clustering of SENTINEL-1A SAR image, were calculated. Lake Constance, Germany has been chosen as the study area. In this study, additionally an interface plugin has been developed and integrated into the open source Quantum GIS software platform. The developed interface allows non-experts to process and extract the shorelines without using any parameters. But, this system requires pre-segmented data as input. Thus, the batch process calculates the required parameters

Gravitating Instantons In 3 Dimensions

We study the Einstein-Chern-Simons gravity coupled to Yang-Mills-Higgs theory in three dimensional Euclidean space with cosmological constant. The classical equations reduce to Bogomol'nyi type first order equations in curved space. There are BPS type gauge theory instanton (monopole) solutions of finite action in a gravitational instanton which itself has a finite action. We also discuss gauge theory instantons in the vacuum (zero action) AdS space. In addition we point out to some exact solutions which are singular.Comment: 17 pages, 4 figures, title has changed, gravitational instanton actions are adde

Energy in Generic Higher Curvature Gravity Theories

We define and compute the energy of higher curvature gravity theories in arbitrary dimensions. Generically, these theories admit constant curvature vacua (even in the absence of an explicit cosmological constant), and asymptotically constant curvature solutions with non-trivial energy properties. For concreteness, we study quadratic curvature models in detail. Among them, the one whose action is the square of the traceless Ricci tensor always has zero energy, unlike conformal (Weyl) gravity. We also study the string-inspired Einstein-Gauss-Bonnet model and show that both its flat and Anti-de-Sitter vacua are stable.Comment: 18 pages, typos corrected, one footnote added, to appear in Phys. Rev.