Radiative transfer theory for polarimetric remote sensing of pine forest

The radiative transfer theory is applied to interpret polarimetric radar backscatter from pine forest with clustered vegetation structures. To take into account the clustered structures with the radiative transfer theory, the scattering function of each cluster is calculated by incorporating the phase interference of scattered fields from each component. Subsequently, the resulting phase matrix is used in the radiative transfer equations to evaluate the polarimetric backscattering coefficients from random medium layers embedded with vegetation clusters. Upon including the multi-scale structures, namely, trunks, primary and secondary branches, as well as needles, we interpret and simulate the polarimetric radar responses from pine forest for different frequencies and looking angles. The preliminary results are shown to be in good agreement with the measured backscattering coefficients at the Landes maritime pine forest during the MAESTRO-1 experiment

Modular Analysis Software for the ALMA Front End Test and Measurement System

A new software library for The ALMA Front End Test and Measurement System (FETMS) will be implemented at the NRAO Technology Center (NTC) to test new front end systems. This library will ensure that these front end systems meet noise temperature specifications and IF output power spectrum specifications, allowing optimal signal-to-noise ratios (SNR) to be made with the receivers. The library is written in PHP and is used to find, analyze, and display test data from FETMS measurements database. It features structured interfaces for simple communication between tests, flexible database retrieval to minimize computation time, universal data structures which utilize the PHP array features to allow for ease in data manipulation, and an adaptable plotter class that gives the user a simple module to plot their data. These features will allow for easier use, quicker maintenance, and more timely upgrades. This library is now running on the FETMS at the NTC and future versions will include more specification test options and the removal of possible bugs.Ope

Dislocation transport and intermittency in the plasticity of crystalline solids

International audienceWhen envisioned at the relevant length scale, plasticity of crystalline solids consists in the transport of dislocations through the lattice. In this paper, transport of dislocations is evidenced by experimental data gathered from high-resolution extensometry carried out on copper single crystals in tension. Spatiotemporal kinematic fields display spatial correlation through characteristic lines intermittently covered by plastic activity. Intermittency shows temporal correlation and power-law distribution of avalanche size. Interpretation of this phenomenon is proposed within the framework of a field dislocation theory attacking the combined problem of dislocation transport and long-range internal stress field development. Intermittency and transport properties show remarkable independence from sample size, aspect ratio, loading rate, and strain-rate sensitivity of the flow stress

Visualising the past – an evaluation of processes and sequences for fingermark recovery from old documents

This study aimed to collect data on the effectiveness of most of the fingermark visualisation reagents currently used on porous surfaces on fingermarks aged for up to 90 years, significantly extending the timescales for which such information exists. A limited subset of the variables associated with processing of old fingermarks was explored, with a focus on the use of 1,8 diazafluoren-9-one (DFO), 1,2-indandione, ninhydrin, and physical developer. These techniques were used in sequence on batches of cheques between 11 and 32 years old, and on documents dating from the 1920s and 1940s. The potential for applying a physical developer enhancement process (blue toning) as the final step in the sequence was also explored. The benefits of using processing sequences on porous items were clearly demonstrated, with all processes in the sequence adding value in terms of additional marks found on the cheques up to 32 years old. In addition, physical developer was found to be capable of developing fingermarks up to 90 years old, whereas the amino acid reagents appear less effective on documents of 70 years and older. An experimental physical developer formulation with reduced environmental impact was found to be as effective as the existing process in these experiments. Blue toning was found to visualise an additional 10-25% of marks, and its wider use after silver-based deposition processes is recommended based on the evidence from this study.Peer reviewedFinal Accepted Versio

2D photonic-crystal optomechanical nanoresonator

We present the optical optimization of an optomechanical device based on a suspended InP membrane patterned with a 2D near-wavelength grating (NWG) based on a 2D photonic-crystal geometry. We first identify by numerical simulation a set of geometrical parameters providing a reflectivity higher than 99.8 % over a 50-nm span. We then study the limitations induced by the finite value of the optical waist and lateral size of the NWG pattern using different numerical approaches. The NWG grating, pierced in a suspended InP 265 nm-thick membrane, is used to form a compact microcavity involving the suspended nano-membrane as end mirror. The resulting cavity has a waist size smaller than 10 $\mu$m and a finesse in the 200 range. It is used to probe the Brownian motion of the mechanical modes of the nanomembrane

β\beta-NMR of Isolated 8^{8}Li+^{+} Implanted into a Thin Copper Film

Depth-controlled $\beta$-NMR was used to study highly spin-polarized $^8$Li in a Cu film of thickness 100 nm deposited onto a MgO substrate. The positive Knight Shifts and spin relaxation data show that $^8$Li occupies two sites at low temperatures, assigned to be the substitutional ($S$) and octahedral ($O$) interstitial sites. Between 50 to 100 K, there is a site change from $O$ to $S$. The temperature dependence of the Knight shifts and spin-lattice relaxation rates at high temperatures, i.e. when all the Li are in the $S$ site, is consistent with the Korringa Law for a simple metal.Comment: Accepted for publication in Phys. Rev.

Qualitative Assessment of Participant Utilization and Satisfaction With the Seattle Senior Farmers’ Market Nutrition Pilot Program

INTRODUCTION: The Seattle Senior Farmers' Market Nutrition Pilot Program delivered fresh fruits and vegetables to homebound seniors in King County, Washington, from June through October 2001. A primary objective of the program was to increase participants' intake of fruits and vegetables. A qualitative study was conducted to examine the impact of the program on participating homebound seniors. METHODS: Semi-structured interviews were performed with 27 participants in their homes to identify benefits and barriers they encountered and to measure their use and sense of satisfaction with the program. RESULTS: Analysis of the transcribed interviews revealed several common themes:  Participants appreciated the variety and quality of the fresh fruits and vegetables. . Some participants would not have had access to fresh fruits and vegetables without the program. . Home-delivered baskets of fresh fruits and vegetables brought participants joy, stimulated interest in healthy foods, and improved quality of life. . The program newsletter supported consumption of fresh produce. CONCLUSION: Program success was rooted in the multiple ways the program addressed potential barriers and reinforced behavioral intent

Searching for Imprints of Circumstellar Material in the Ultraviolet Spectra of Type Ia Supernovae

Type Ia supernovae (SNe Ia), having large and standard luminosities, are our primary dark energy probe. Although we believe that SNe Ia are produced by white dwarfs (WDs) in binary systems, the type of companion star is still unclear. Using a SN as a backlight, we can probe the gas along the line-of-sight to a SN Ia, including possible circumstellar gas from the companion star. For a handful of SNe Ia, repeated measurements of the narrow Na D doublet have shown variable absorption that we interpret as the recombination of circumstellar Na atoms after being ionized by the initial UV SN flash. This is perhaps the best evidence that at least some SNe Ia have a main-sequence or red-giant companion. Using Hubble Space Telescope ultraviolet spectroscopy, we probe several additional species with varying ionization potentials for 8 SNe Ia. Since these features have different ionization potentials from species seen in the optical, they probe new physical regions of the circumstellar system. Although these features can potentially reveal previously hidden circumstellar gas, we do not detect any variable features in our best examples, indicating that these systems had no circumstellar gas or that the gas was particularly distant.Ope