SALT Spectropolarimetry and Self-Consistent SED and Polarization Modeling of Blazars

We report on recent results from a target-of-opportunity program to obtain spectropolarimetry observations with the Southern African Large Telescope (SALT) on flaring gamma-ray blazars. SALT spectropolarimetry and contemporaneous multi-wavelength spectral energy distribution (SED) data are being modelled self-consistently with a leptonic single-zone model. Such modeling provides an accurate estimate of the degree of order of the magnetic field in the emission region and the thermal contributions (from the host galaxy and the accretion disk) to the SED, thus putting strong constraints on the physical parameters of the gamma-ray emitting region. For the specific case of the $\gamma$-ray blazar 4C+01.02, we demonstrate that the combined SED and spectropolarimetry modeling constrains the mass of the central black hole in this blazar to $M_{\rm BH} \sim 10^9 \, M_{\odot}$.Comment: Submitted to Galaxies - Proceedings of "Polarized Emission from Astrophysical Jets", Ierapetra, Crete, June 12 - 16, 201

A Novel Method for 3D-Segmentation of Vascular Images

Constructing the accurate digital model of vessel networks is critical to vascular tissue engineering, in which the segmentation of vessel plays an important role. However, the existing segmentation methods are not able to achieve the goal of accurate segmentation of vessel networks. This paper presents the development of a method for vessel segmentation based on a data structure of octree and 3D region growing. Firstly, the volume data of vessel images are divided into different data groups according to the predetermined depth value of octree, and then the optimal slices sequence is defined by analyzing the octree’s nodes which contain the vessel region. Then, the vessel segmentation is conducted from the vessels images of octree nodes based on 3D region growing. Finally, the treated data blocks are reset and the segmentation results of the whole volume data are obtained. By applying this method to the volume data of vascular images from MRA, accurate vessel segmentation results are achieved. This work would represent a significant advance for digital modeling of vessel networks. Key Words: Vascular tissue engineering; Image segmentation; Region growing; Octre

Spectrum of the Anomalous Microwave Emission in the North Celestial Pole with WMAP 7-Year data

We estimate the frequency spectrum of the diffuse anomalous microwave emission (AME) on the North Celestial Pole (NCP) region of the sky with the Correlated Component Analysis (CCA) component separation method applied to WMAP 7-yr data. The NCP is a suitable region for this analysis because the AME is weakly contaminated by synchrotron and free-free emission. By modeling the AME component as a peaked spectrum we estimate the peak frequency to be $21.7\pm0.8$\,GHz, in agreement with previous analyses which favored $\nu_{\rm p}<23$\,GHz. The ability of our method to correctly recover the position of the peak is verified through simulations. We compare the estimated AME spectrum with theoretical spinning dust models to constrain the hydrogen density $n_{\rm H}$. The best results are obtained with densities around 0.2--0.3\,cm$^{-3}$, typical of warm ionised medium (WIM) to warm neutral medium (WNM) conditions. The degeneracy with the gas temperature prevents an accurate determination of $n_{\rm H}$, especially for low hydrogen ionization fractions, where densities of a few cm$^{-3}$ are also allowed.Comment: 13 pages, 6 figures, published in Advances in Astronom

Cost of Production System Budgets

The Resource and Environmental Policy (REP) Division of CARD needed accurate cost of production system (COPS) budgets to integrate into its existing environmental modeling system. Cost and Returns Estimator (CARE) crop budgets were reorganized and modified to create a unique COPS budget for each rotation, tillage, and irrigation combination in every Agricultural Sector Model (ASM) region in the 12-state area encompassing the Corn Belt, Lake States, and Northern Plains. These consistent budgets allow comparison across the study region and provide cost of production data for environmental and agricultural policy analysis

Accurate small-signal equivalent circuit modelling of resonant tunneling diodes to 110 GHz

This article presents a novel, on-wafer deembedding technique for the accurate small-signal equivalent circuit modeling of resonant tunneling diodes (RTDs). The approach is applicable to stabilized RTDs, and so enables the modeling of the negative differential resistance (NDR) region of the device's current-voltage (I-V) characteristics. Furthermore, a novel quasi-analytical procedure to determine all the equivalent circuit elements from the deembedded S-parameter data is developed. Extraction results of a 10 μm × 10 μm stabilized, low-current density RTD at different bias points show excellent fits between modeled and measured S-parameters up to 110 GHz