Off-nadir antenna bias correction using Amazon rain forest sigma deg data

The radar response from the Amazon rain forest was studied to determine the suitability of this region for use as a standard target to calibrate a scatterometer like that proposed for the National Ocean Satellite System (NOSS). Backscattering observations made by the SEASAT-1 scatterometer system show the Amazon rain forest to be a homogeneous, azimuthally-isotropic, radar target which is insensitive to polarization. The variation with angle of incidence may be adequately modeled as sigma deg (dB) = alpha theta + beta with typical values for the incidence-angle coefficient from 0.07 dB deg to 0.15 dB/deg. A small diurnal effect occurs, with measurements at sunrise being 0.5 dB to 1 dB higher than the rest of the day. Maximum likelihood estimation algorithms are presented which permit determination of relative bias and true pointing angle for each beam. Specific implementation of these algorithms for the proposed NOSS scatterometer system is also discussed

Average transmission probability of a random stack

The transmission through a stack of identical slabs that are separated by gaps with random widths is usually treated by calculating the average of the logarithm of the transmission probability. We show how to calculate the average of the transmission probability itself with the aid of a recurrence relation and derive analytical upper and lower bounds. The upper bound, when used as an approximation for the transmission probability, is unreasonably good and we conjecture that it is asymptotically exact.Comment: 10 pages, 6 figure

Education Program for Improved Water Quality in Copano Bay Final Report

The Copano Bay watershed covers approximately 1.4 million acres encompassing portions of Karnes, Bee, Goliad, Refugio, San Patricio and Aransas counties. Copano Bay and its main tributaries, the Mission and Aransas rivers, were placed on the Texas Commission on Environmental Quality (TCEQ) 303(d) list in 1998 due to levels of bacteria that exceed water quality standards established to protect oyster waters use. A Total Maximum Daily Load (TMDL) program was initiated in September 2003 to identify and assess sources of these bacteria. The Center for Research in Water Resources at the University of Texas at Austin (UT CRWR) was funded by TCEQ to conduct computer-based modeling to determine the bacterial loading and reductions necessary to attain water quality standards. Subsequently Texas A&M University-Corpus Christi (TAMU-CC) conducted bacterial source tracking (BST) with funding from Texas General Land Office (TGLO) and the Coastal Bend Bays and Estuaries Program (CBBEP) to determine actual sources of bacteria. Due to the findings of the initial efforts of the TMDL and concerns voiced by stakeholders in the watershed, Texas AgriLife Extension Service was awarded a Clean Water Act § 319(h) Nonpoint Source Grant from the Texas State Soil and Water Conservation Board (TSSWCB) and the U.S. Environmental Protection Agency. The overall goal of this project was to improve water quality in Copano Bay and its tributaries by increasing awareness of water quality issues throughout the watershed. This increased awareness was to be accomplished by providing education and demonstrations for land and livestock owners in the watershed on best management practices (BMPs) to decrease or prevent bacteria from entering waterways. Through creation of a project website, 52 educational programs, and nine one-on-one consultations over the span of the project, we have reached 5,408 residents in and around the Copano Bay watershed. Additionally, through this project all data collected for the initial TMDL efforts was re-evaluated and findings were presented in the “Task 2 Report.” Project members developed a curriculum for horse owners, “A Guide to Good Horsekeeping” that addressed BMPs specific to horse operations. Land and livestock owners who had already implemented BMPs or were interested in implementing BMPs were given a participation certificate

Minimax mean estimator for the trine

We explore the question of state estimation for a qubit restricted to the $x$-$z$ plane of the Bloch sphere, with the trine measurement. In our earlier work [H. K. Ng and B.-G. Englert, eprint arXiv:1202.5136[quant-ph] (2012)], similarities between quantum tomography and the tomography of a classical die motivated us to apply a simple modification of the classical estimator for use in the quantum problem. This worked very well. In this article, we adapt a different aspect of the classical estimator to the quantum problem. In particular, we investigate the mean estimator, where the mean is taken with a weight function identical to that in the classical estimator but now with quantum constraints imposed. Among such mean estimators, we choose an optimal one with the smallest worst-case error-the minimax mean estimator-and compare its performance with that of other estimators. Despite the natural generalization of the classical approach, this minimax mean estimator does not work as well as one might expect from the analogous performance in the classical problem. While it outperforms the often-used maximum-likelihood estimator in having a smaller worst-case error, the advantage is not significant enough to justify the more complicated procedure required to construct it. The much simpler adapted estimator introduced in our earlier work is still more effective. Our previous work emphasized the similarities between classical and quantum state estimation; in contrast, this paper highlights how intuition gained from classical problems can sometimes fail in the quantum arena.Comment: 18 pages, 3 figure

Periodic and discrete Zak bases

Weyl's displacement operators for position and momentum commute if the product of the elementary displacements equals Planck's constant. Then, their common eigenstates constitute the Zak basis, each state specified by two phase parameters. Upon enforcing a periodic dependence on the phases, one gets a one-to-one mapping of the Hilbert space on the line onto the Hilbert space on the torus. The Fourier coefficients of the periodic Zak bases make up the discrete Zak bases. The two bases are mutually unbiased. We study these bases in detail, including a brief discussion of their relation to Aharonov's modular operators, and mention how they can be used to associate with the single degree of freedom of the line a pair of genuine qubits.Comment: 15 pages, 3 figures; displayed abstract is shortened, see the paper for the complete abstrac

The moisture effect on 223Ra and 224Ra measurements using Mn-cartridges

Important processes in the ocean can be evaluated with radioactive nuclides, including radium isotopes. An approach for quantifying radium isotopes in seawater with in-situ pumps has been developed in advance of the GEOTRACES program [1]. Precise measurements of 223Ra and 224Ra by means of the delayed coincidence counting system (RaDeCC) [2] are dependent on the moisture content of the medium [3]. In order to verify the optimum moisture content for this new approach, a set of measurements of the Mn-cartridge standards under different moisture conditions was conducted, as this was done previously for acrylic fiber. At a time, an amount of water equivalent to 5% of the cartridges weight was added, and the activities were determined. The variation of 224Ra activity occurs mainly between 0 to 15% of humidity. Under moisture conditions higher than 15%, the emanation efficiency reaches an optimum plateau until 100% of moisture. This result differs slightly from those found for 224Ra measurements using the acrylic fiber (plateau from 30 to 100 %) [3]. The 223Ra Mn-cartridge standard reaches the plateau under 5% of humidity, and above 50% moisture the activity seems to decrease. Considering the counting error (7%), it is hard to state that the effect of the moisture is critical. However, this decrease can be related to the shorter half-life of the 219Rn compared to the time needed to its diffusion through the water film, which could be a reason for the frequently observed lower efficiency of the 223Ra channel of the RaDeCC system [4]. [1] Henderson et al. (2013) J. Radioanal. Nucl. Chem. 296, 357–362. [2] Moore and Arnold (1996) J. Geophys. Res. 101, 321–1329. [3] Sun and Torgersen (1998) Mar. Chem. 61, 163–171. [4] Charette et al. (2012) Limnol. Oceanogr. 10, 451–463

Migrating Songbirds on Stopover Prepare for, and Recover from, Oxidative Challenges Posed by Long-Distance Flight

Managing oxidative stress is an important physiological function for all aerobic organisms, particularly during periods of prolonged high metabolic activity, such as long-distance migration across ecological barriers. However, no previous study has investigated the oxidative status of birds at different stages of migration and whether that oxidative status depends on the condition of the birds. In this study, we compared (1) energy stores and circulating oxidative status measures in (a) two species of Neotropical migrants with differing migration strategies that were sampled at an autumn stopover site before an ecological barrier; and (b) a species of trans-Saharan migrant sampled at a spring stopover site after crossing an ecological barrier; and (2) circulating oxidative measures and indicators of fat metabolism in a trans-Saharan migrant after stopovers of varying duration (0–8 nights), based on recapture records. We found fat stores to be positively correlated with circulating antioxidant capacity in Blackpoll Warblers and Red-eyed Vireos preparing for fall migration on Block Island, USA, but uncorrelated in Garden Warblers on the island of Ponza, Italy, after a spring crossing of the Sahara Desert and Mediterranean Sea. In all circumstances, fat stores were positively correlated with circulating lipid oxidation levels. Among Garden Warblers on the island of Ponza, fat anabolism increased with stopover duration while oxidative damage levels decreased. Our study provides evidence that birds build antioxidant capacity as they build fat stores at stopover sites before long flights, but does not support the idea that antioxidant stores remain elevated in birds with high fuel levels after an ecological barrier. Our results further suggest that lipid oxidation may be an inescapable hazard of using fats as the primary fuel for flight. Yet, we also show that birds on stopover are capable of recovering from the oxidative damage they have accrued during migration, as lipid oxidation levels decrease with time on stopover. Thus, the physiological strategy of migrating songbirds may be to build prophylactic antioxidant capacity in concert with fuel stores at stopover sites before a long-distance flight, and then repair oxidative damage while refueling at stopover sites after long-distance flight

Precision Measurement of the 29Si, 33S, and 36Cl Binding Energies

The binding energies of 29Si, 33S, and 36Cl have been measured with a relative uncertainty $< 0.59 \times 10^{-6}$ using a flat-crystal spectrometer. The unique features of these measurements are 1) nearly perfect crystals whose lattice spacing is known in meters, 2) a highly precise angle scale that is derived from first principles, and 3) a gamma-ray measurement facility that is coupled to a high flux reactor with near-core source capability. The binding energy is obtained by measuring all gamma-rays in a cascade scheme connecting the capture and ground states. The measurements require the extension of precision flat-crystal diffraction techniques to the 5 to 6 MeV energy region, a significant precision measurement challenge. The binding energies determined from these gamma-ray measurements are consistent with recent highly accurate atomic mass measurements within a relative uncertainty of $4.3 \times 10^{-7}$. The gamma-ray measurement uncertainties are the dominant contributors to the uncertainty of this consistency test. The measured gamma-ray energies are in agreement with earlier precision gamma-ray measurements.Comment: 13 pages, 4 figure

Ammonium bis(salicylaldehyde thiosemicarbazonato)ferrate(III), a supramolecular material containing low-spin FeIII

The synthesis and crystal structure (100 K) of the title com­pound, ammonium bis­[salicyl­aldehyde thio­semi­car­ba­zon­ato(2−)-κ3O,N1,S]iron(III), NH4[Fe(C8H7N3OS)2], is reported. The asymmetric unit consists of an octa­hedral [FeIII(thsa)2]− fragment, where thsa2− is salicyl­aldehyde thio­semi­car­ba­zon­ate(2−), and an NH4+ cation. Each thsa2− ligand binds via the thiol­ate S, the imine N and the phenolate O donor atoms, resulting in an FeIIIS2N2O2 chromophore. The ligands are orientated in two perpendicular planes, with the O and S atoms in cis and the N atoms in trans positions. The FeIII ion is in the low-spin state at 100 K. The crystal structure belongs to a category I order–disorder (OD) family. It is a polytype of a maximum degree of order (MDO). Fragments of the second MDO polytype lead to systematic twinning by pseudomerohedry

Systematic review of fatty acid composition of human milk from mothers of preterm compared to full-term infants

Background: Fatty acid composition of human milk serves as guidance for the composition of infant formulae. The aim of the study was to systematically review data on the fatty acid composition of human milk of mothers of preterm compared to full-term infants. Methods: An electronic literature search was performed in English (Medline and Medscape) and German (SpringerLink) databases and via the Google utility. Fatty acid compositional data for preterm and fullterm human milk were converted to differences between means and 95% confidence intervals. Results: We identified five relevant studies publishing direct comparison of fatty acid composition of preterm versus full-term human milk. There were no significant differences between the values of the principal saturated and monounsaturated fatty acids. In three independent studies covering three different time points of lactation, however, docosahexaenoic acid (DHA) values were significantly higher in milk of mothers of preterm as compared to those of full-term infants, with an extent of difference considered nutritionally relevant. Conclusion: Higher DHA values in preterm than in full-term human milk underlines the importance of using own mother's milk for feeding preterm babies and raises the question whether DHA contents in preterm formulae should be higher than in formulae for full-term infants. Copyright (c) 2008 S. Karger AG, Basel