Spectra of Maser Radiation from a Turbulent, Circumnuclear Accretion Disk. III. Circular polarization

Calculations are performed for the circular polarization of maser radiation from a turbulent, Keplerian disk that is intended to represent the sub-parsec disk at the nucleus of the galaxy NGC4258. The polarization in the calculations is a result of the Zeeman effect in the regime in which the Zeeman splitting is much less than the spectral linebreadth. Plausible configurations for turbulent magnetic and velocity fields in the disk are created by statistical methods. This turbulence, along with the Keplerian velocity gradients and the blending of the three hyperfine components to form the $6_{16} - 5_{23}$ masing transition of water, are key ingredients in determining the appearance of the polarized spectra that are calculated. These spectra are quite different from the polarized spectra that would be expected for a two-level transition where there is no hyperfine structure. The effect of the hyperfine structure on the polarization is most striking in the calculations for the maser emission that represents the central (or systemic) features of NGC4258. Information about magnetic fields is inferred from observations for polarized maser radiation and bears on the structure of accretion disks.Comment: Latex, uses aastex, eucal, to be published in the Astrophysical Journa

Low noise high performance 50nm T-gate metamorphic HEMT with cut-off frequency f_T of 440 GHz for millimeterwave imaging receivers applications

The 50 nm m-HEMT exhibits extremely high f<sub>T</sub>, of 440GHz, low F<sub>min</sub> of 0.7 dB, associated gain of 13 dB at 26 GHz with an exceptionally high Id of 200 mA/mm and gm of 950 ms/mm at low noise biased point

A method for determining landing runway length for a STOL aircraft

Based on data obtained from flight tests of the augmentor wing jet STOL research aircraft, a method is proposed for determining the length of the landing runway for powered-lift STOL aircraft. The suggested method determines runway landing length by summing three segments: the touchdown-dispersion distance, the transition distance from touchdown to application of brakes, and the stopping distance after brakes are applied. It is shown how the landing field length can be reduced either through improved autoland system design or by providing the pilot with appropriate information to allow him to identify a "low probability" long or short landing and to execute a go-around. The proposed method appears to determine a safe runway landing length for the STOL application and offers the potential for reducing runway length if great emphasis is placed on a short-runway capability. FAR Parts 25 and 121 appear conservative and suitable for the situation where no great emphasis is placed on reducing the runway length requirement

Reconciling taxonomy and phylogenetic inference: formalism and algorithms for describing discord and inferring taxonomic roots

Although taxonomy is often used informally to evaluate the results of phylogenetic inference and find the root of phylogenetic trees, algorithmic methods to do so are lacking. In this paper we formalize these procedures and develop algorithms to solve the relevant problems. In particular, we introduce a new algorithm that solves a "subcoloring" problem for expressing the difference between the taxonomy and phylogeny at a given rank. This algorithm improves upon the current best algorithm in terms of asymptotic complexity for the parameter regime of interest; we also describe a branch-and-bound algorithm that saves orders of magnitude in computation on real data sets. We also develop a formalism and an algorithm for rooting phylogenetic trees according to a taxonomy. All of these algorithms are implemented in freely-available software.Comment: Version submitted to Algorithms for Molecular Biology. A number of fixes from previous versio

A Comparative analysis of satellite-based approaches for aboveground biomass estimation in the Brazilian Amazon.

The moist tropical forest in the Amazon has been regarded as an important part in global carbon budget. Deforestation since the 1970s has made it an important carbon source, but the rapid growth of secondary vegetation may compensate its negative role to a certain degree. In order to reduce the uncertainty in carbon estimation at regional or global scale, it is critical to timely provide the carbon spatial distribution with high accuracy. Remotely sensed data have become the primary source for mapping carbon storage at local or regional scale. Thanks to the NASA LBA-ECO funded projects (1998 - 2008), we have explored aboveground biomass (AGB) estimation in the eastern and western Brazilian Amazon with Landsat Thematic Mapper (TM) images. Different TM spectral responses and textures were examined for improving the AGB estimation performance. Subpixel information extracted from the spectral mixture analysis of TM multispectral images was also examined. Entropy was used to analyze the complexity of forest stand structure and to examine impacts of different stand structures on TM reflectance data. This research indicates that estimating AGB is still a challenge task, especially for the sites with complicated biophysical environments. The TM spectral responses are more suitable for AGB estimation in the sites with relatively simple forest stand structure than for the sites with complicated forest stand structure. Conversely, textures appear more important than spectral responses in AGB estimation in the sites with complicated forest stand structure. A combination of spectral responses and textures improves AGB estimation performance. Using fraction images perform better for successional vegetation AGB estimation than using TM spectral signatures. However, both models based on TM spectral signatures and fractions provided poor performance for primary forest AGB estimation. The complex stand structure and associated canopy shadow greatly reduced relationships between AGB and TM reflectance or fraction images. Different study areas having various biophysical conditions affect AGB estimation performance. More research is needed to focus on the integration of optical and radar data, the use of multisource data, and the selection of suitable variables and algorithms for AGB estimation at different scales. The AGB estimates at local scale may be used as a reference data for calibrating or validating the model-based carbon estimates at regional or global scale. Sessão: 3. Integrando fluxos de carbono para a regi?o a partir de medidas em pontos de coleta, torres e aeronaves. Tipo de Apresentação: Oral(Apresentação oral

Preparation and Characterization of Cerium (III) Doped Captopril Nanoparticles and Study of their Photoluminescence Properties

Indexación: Web of Science. DOAJ.In this research Ce3+ doped Captopril nanoparticles (Ce3+ doped CAP-NP) were prepared by a cold welding process and have been studied. Captopril may be applied in the treatment of hypertension and some types of congestive heart failure and for preventing kidney failure due to high blood pressure and diabetes. CAP-NP was synthesized by a cold welding process. The cerium nitrate was added at a ratio of 10% and the optical properties have been studied by photoluminescence (PL). The synthesized compounds were characterized by Fourier transform infrared spectroscopy. The size of CAP-NP was calculated by X-ray diffraction (XRD). The size of CAP-NP was in the range of 50 nm. Morphology of surface of synthesized nanoparticles was studied by scanning electron microscopy (SEM). Finally the luminescence properties of undoped and doped CAP-NP were compared. PL spectra from undoped CAP-NP show a strong pack in the range of 546 nm after doped cerium ion into the captopril appeared two bands at 680 and 357 nm, which is ascribed to the well-known 5d–4f emission band of the cerium.http://www.degruyter.com/view/j/chem.2016.14.issue-1/chem-2016-0008/chem-2016-0008.xm

Satellite estimation of aboveground biomass and impacts of forest stand structure.

Heterogeneous Amazonian landscapes and complex forest stand structure often make aboveground biomass (AGB) estimation difficult. In this study, spectral mixture analysis was used to convert a Landsat Thematic Mapper (TM) image into green vegetation, shade, and soil fraction images. Entropy was used to analyze the complexity of forest stand structure and to examine impacts of different stand structures on TM reflectance data. The relationships between AGB and fraction images or TM spectral signatures were investigated based on successional and primary forests, respectively, and AGB estimation models were developed for both types of forests. Our findings indicate that the AGB estimation models using fraction images perform better for successional forest biomass estimation than using TM spectral signatures. However, both models based on TM spectral signatures and fractions provided poor performance for primary forest biomass estimation. The complex stand structure and associated canopy shadow greatly reduced relationships between AGB and TM reflectance or fraction images