Microscopic mechanism for mechanical polishing of diamond (110) surfaces

Mechanically induced degradation of diamond, as occurs during polishing, is studied using total--energy pseudopotential calculations. The strong asymmetry in the rate of polishing between different directions on the diamond (110) surface is explained in terms of an atomistic mechanism for nano--groove formation. The post--polishing surface morphology and the nature of the polishing residue predicted by this mechanism are consistent with experimental evidence.Comment: 4 pages, 5 figure

Engineering Art Galleries

The Art Gallery Problem is one of the most well-known problems in Computational Geometry, with a rich history in the study of algorithms, complexity, and variants. Recently there has been a surge in experimental work on the problem. In this survey, we describe this work, show the chronology of developments, and compare current algorithms, including two unpublished versions, in an exhaustive experiment. Furthermore, we show what core algorithmic ingredients have led to recent successes

Comparison of CDMS [100] and [111] oriented germanium detectors

The Cryogenic Dark Matter Search (CDMS) utilizes large mass, 3" diameter $\times$ 1" thick target masses as particle detectors. The target is instrumented with both phonon and ionization sensors and comparison of energy in each channel provides event-by-event classification of electron and nuclear recoils. Fiducial volume is determined by the ability to obtain good phonon and ionization signal at a particular location. Due to electronic band structure in germanium, electron mass is described by an anisotropic tensor with heavy mass aligned along the symmetry axis defined by the [111] Miller index (L valley), resulting in large lateral component to the transport. The spatial distribution of electrons varies significantly for detectors which have their longitudinal axis orientations described by either the [100] or [111] Miller indices. Electric fields with large fringing component at high detector radius also affect the spatial distribution of electrons and holes. Both effects are studied in a 3 dimensional Monte Carlo and the impact on fiducial volume is discussed.Comment: Low Temperature Detector 14 conference proceedings to be published in the Journal of Low Temperature Physic

Identificação de QTLs ligados a resistência ao crestamento bacteriano em Phaseolus vulgaris.

O objetivo deste trabalho foi identificar QTLs associados à resistência do feijoeiro ao crestamento bacteriano comum, a fim de auxiliar a seleção com marcadores

Gamma Ray Large Area Space Telescope (GLAST) Balloon Flight Data Handling Overview

The GLAST Balloon Flight Engineering Model (BFEM) represents one of 16 towers that constitute the Large Area Telescope (LAT), a high-energy (>20 MeV) gamma-ray pair-production telescope being built by an international partnership of astrophysicists and particle physicists for a satellite launch in 2006. The prototype tower consists of a Pb/Si pair-conversion tracker (TKR), a CsI hodoscopic calorimeter (CAL), an anti-coincidence detector (ACD) and an autonomous data acquisition system (DAQ). The self-triggering capabilities and performance of the detector elements have been previously characterized using positron, photon and hadron beams. External target scintillators were placed above the instrument to act as sources of hadronic showers. This paper provides a comprehensive description of the BFEM data-reduction process, from receipt of the flight data from telemetry through event reconstruction and background rejection cuts. The goals of the ground analysis presented here are to verify the functioning of the instrument and to validate the reconstruction software and the background-rejection scheme.Comment: 5 pages, 4 figures, to be published in IEEE Transacations on Nuclear Science, August 200

Effect of Solution pH on the Removal of Paracetamol by Activated Carbon of Dende Coconut Mesocarp

Activated carbon of dende coconut mesocarp was used to investigate the removal of paracetamol from water by adsorption. The results indicated that the retention of paracetamol was favored in activated carbon with neutral surface properties. The textural features and presence of a transport pores network contributed to ensuring the accessibility to the inner porosity, and the microporosity must be large enough to accommodate the paracetamol molecule. Chemisorption and mainly physisorption are important in the paracetamol removal. Pseudo-second order equation and Langmuir model were chosen to best present the experimental data. The adsorption process was non-spontaneous and endothermic with increase in system disorder

Best management practices and environmental management in aquaculture: indicators for monitoring in multiple scales.

Abstract: The promotion of sustainable aquaculture depends on the documented adoption of Best Management Practices (BMPs), associated with the monitoring of environmental health, of the availability of natural resources (especially uncontaminated waters and sediments), and of the efficient use of inputs. In order to ensure a traceable and organized procedure to help fish farmers to comply with these requisites, a set of environmental performance indicators has been integrated into an Environmental Impact Assessment (EIA) system, under the coordination of the Brazilian Ministry of Fisheries and Aquaculture (MPA), through a research project carried out in the Furnas reservoir (Minas Gerais State, Brazil). This choice of location aims at supporting a national policy, dedicated to implement ?Aquaculture Parks? in the large reservoirs associated with hydroelectric facilities in the country. These ?Parks? have been delimitated in selected areas, following careful diagnostics of hydrodynamics, carrying capacity evaluations, multiple water uses and conflicting interests, to receive permits to install cages for fish production. One provision of said policy charges MPA to offer producers with monitoring programs related with environmental impact and social benefit assessments of these aquaculture ventures. A challenge for such monitoring programs is to encompass the multiple scales represented by (i) the individual aquaculture ventures (be these small or large numbers of fish cages for each fish farmer), (ii) the collective association of producers in an ?aquaculture park?, and (iii) the community at large eventually affected by these businesses. Furthermore, the monitoring procedure should emphasize the ability to promote and recommend adoption of BMPs, while facilitating the record keeping of environmental quality and resource carrying capacity information. The primary component of this record keeping, environmental management and resource monitoring procedure has been formulated as a ?Weighted Impact Assessment System for Best Management Practices in Aquaculture? (APOIA-Aquaculture), comprised of 68 indicators integrated in a multi-attribute platform to assess the ?Spatial organization? of the enterprises (in a set of 22 indicators), the analytical conditions of ?Water quality? (14 indicators), and ?Quality of the sediments? (09 indicators), and the conditions regarding ?Management, nutrition and safety? (23 indicators). A series of case studies has been carried out at the Furnas reservoir, in order to check the flexibility of the impact assessment system towards the different enterprise typologies, and its applicability as an environmental management tool for producers. Interestingly, a subset of ?sediment quality indicators? is frequently showing sensitivity as a record of mismanagement, especially those linked with inadequate feeding management. For instance, organic matter and phosphate contents increased markedly from sediments sampled ~10m upstream (considering the local current lows) as compared to just under the cages. The main reasons for these changes seemed to be the inadequate identification of cages, with consequent poor control on feeding practices and impossible bookkeeping. Such indicator interactions, and related management tradeoffs and improved practice recommendations, are stressed in 4th International Worksho

Validation of Phonon Physics in the CDMS Detector Monte Carlo

The SuperCDMS collaboration is a dark matter search effort aimed at detecting the scattering of WIMP dark matter from nuclei in cryogenic germanium targets. The CDMS Detector Monte Carlo (CDMS-DMC) is a simulation tool aimed at achieving a deeper understanding of the performance of the SuperCDMS detectors and aiding the dark matter search analysis. We present results from validation of the phonon physics described in the CDMS-DMC and outline work towards utilizing it in future WIMP search analyses.Comment: 6 Pages, 5 Figures, Proceedings of Low Temperature Detectors 14 Conferenc