Hall effect magnetometer

A magnetometer which uses a single crystal of bismuth selenide is described. The rhombohedral crystal structure of the sensing element is analyzed. The method of construction of the magnetometer is discussed. It is stated that the sensing crystal has a positive or negative Hall coefficient and a carrier concentration of about 10 to the 18th power to 10 to the 20th power per cubic centimeter

Magnetometer uses bismuth-selenide

Characteristics of bismuth-selenide magnetometer are described. Advantages of bismuth-selenide magnetometer over standard magnetometers are stressed. Thermal stability of bismuth-selenide magnetometer is analyzed. Linearity of output versus magnetic field over wide range of temperatures is reported

Properties of crystalline bismuth selenide and its use as a Hall effect magnetometer

Single crystals of n-type Bi2Se3 grown by the Bridgman technique are found to make excellent Hall effect magnetometers. Plots of Hall resistivity sub yx against magnetic field B to 10 tesla are linear to within 1 percent. Furthermore, the slope of the sub yx against B curve varies by about 1 percent in the region 1.1 to 35 K and by less than 20 percent in the region 1.1 to 300 K. Analysis of galvanomagnetic measurements indicate the samples have semimetallic densities of approximately 10 to the 25th power/cu cm, with two band conduction and near carrier compensation. Reflectivity measurements suggest a band gap of approximately 0.08 eV for the samples. The temperature dependence of mobility is also measured. A series of 50 direct immersions into liquid helium and liquid nitrogen demonstrate the reliability of Bi2Se3 magnetometers for cryogenic use

Hot methane line lists for exoplanet and brown dwarf atmospheres

We present comprehensive experimental line lists of methane (CH4) at high temperatures obtained by recording Fourier transform infrared emission spectra. Calibrated line lists are presented for the temperatures 300 - 1400 degC at twelve 100 degC intervals spanning the 960 - 5000 cm-1 (2.0 - 10.4 microns) region of the infrared. This range encompasses the dyad, pentad and octad regions, i.e., all fundamental vibrational modes along with a number of combination, overtone and hot bands. Using our CH4 spectra, we have estimated empirical lower state energies (Elow in cm-1) and our values have been incorporated into the line lists along with line positions (cm-1) and calibrated line intensities (S' in cm molecule-1). We expect our hot CH4 line lists to find direct application in the modeling of planetary atmospheres and brown dwarfs.Comment: Supplementary material is provided via the Astrophysical Journal referenc

Feasibility and utility of mapping disease risk at the neighbourhood level within a Canadian public health unit: an ecological study

<p>Abstract</p> <p>Background</p> <p>We conducted spatial analyses to determine the geographic variation of cancer at the neighbourhood level (dissemination areas or DAs) within the area of a single Ontario public health unit, Wellington-Dufferin-Guelph, covering a population of 238,326 inhabitants. Cancer incidence data between 1999 and 2003 were obtained from the Ontario Cancer Registry and were geocoded down to the level of DA using the enhanced Postal Code Conversion File. The 2001 Census of Canada provided information on the size and age-sex structure of the population at the DA level, in addition to information about selected census covariates, such as average neighbourhood income.</p> <p>Results</p> <p>Age standardized incidence ratios for cancer and the prevalence of census covariates were calculated for each of 331 dissemination areas in Wellington-Dufferin-Guelph. The standardized incidence ratios (SIR) for cancer varied dramatically across the dissemination areas. However, application of the Moran's I statistic, a popular index of spatial autocorrelation, suggested significant spatial patterns for only two cancers, lung and prostate, both in males (p < 0.001 and p = 0.002, respectively). Employing Bayesian hierarchical models, areas in the urban core of the City of Guelph had significantly higher SIRs for male lung cancer than the remainder of Wellington-Dufferin-Guelph; and, neighbourhoods in the urban and surrounding rural areas of Orangeville exhibited significantly higher SIRs for prostate cancer. After adjustment for age and spatial dependence, average household income attenuated much of the spatial pattern of lung cancer, but not of prostate cancer.</p> <p>Conclusion</p> <p>This paper demonstrates the feasibility and utility of a systematic approach to identifying neighbourhoods, within the area served by a public health unit, that have significantly higher risks of cancer. This exploratory, ecologic study suggests several hypotheses for these spatial patterns that warrant further investigations. To the best of our knowledge, this is the first Canadian study published in the peer-reviewed literature estimating the risk of relatively rare public health outcomes at a very small areal level, namely dissemination areas.</p

Pelletizing

DURING the last 15 or 20 years we have witnessed an extra-ordinary increase in the quantity of artificial agglomera-tes used in blast-furnace burdens. This expansion has occurred in two fields, the first being sintering, a technique applied particularly to the agglomeration of low grade 'earthy' ores and to screenings from high quality Jump

Evaluación preliminar de condensadores de rocío y su utilización para riego de plántulas de árboles en Puerto Rico

Dew condensers have been proposed as a means to reduce drought&nbsp;mortality of tree seedlings in early stages of reforestation projects. We&nbsp;investigated the amount of dew condensate produced by locally constructed&nbsp;dew condensers, constructed with three different infrared emitting&nbsp;surfaces: standard polyethylene/ TiO2 / BaSO4 foil, thermoplastic polyolefin&nbsp;(TPO), and plastic coated with locally available Lanco UrethanizerTM8&nbsp;roofing paint. All surfaces produced similar amounts of total dew condensate,&nbsp;typically ranging between 0.05 and 0.25 L/m2/night. However, the materials&nbsp;differed in the fraction of dew running off the surfaces, which represents the&nbsp;water available for tree seedlings. Highest runoff fractions were obtained&nbsp;with painted surfaces, followed by polyethylene and polyolefin surfaces,&nbsp;respectively. Considerably greater amounts of nightly dew condensate&nbsp;were observed during the winter than in summer, attributed to differences&nbsp;in night length and cloud cover. A commercially available dew condenser,&nbsp;the Groasis WaterboxxTM, did not generate more than 0.04 L per night of&nbsp;runoff dew, due primarily to a small condenser surface area of &lt; 0.2 m2. A&nbsp;field study showed that 1 m2 dew condensers maintained the root zone of&nbsp;mahogany seedlings at matric potentials &gt; -60 kPa during dry spells. Overall,&nbsp;results indicated that passive dew condensers with condenser areas of 1 m2&nbsp;are capable of producing sufficient water for survival of small tree seedlings&nbsp;during drought periods.Los condensadores de rocío se han propuesto como mecanismo para&nbsp;proveer agua a plántulas de árboles en etapas iniciales de reforestación. Se&nbsp;investigó el potencial de condensadores de fabricación local para producir&nbsp;agua. Se compararon condensadores construidos con tres diferentes&nbsp;superficies emisoras en infrarrojo: lámina estándar de polietileno impregnado&nbsp;con TiO2 y BaSO4, poli-olefina termoplástica (TPO), y plástico recubierto con&nbsp;pintura Lanco UrethanizerTM disponible en ferreterías locales. Todas las&nbsp;superficies produjeron cantidades similares de condensado total de rocío,&nbsp;por lo general entre 0.05 y 0.25 L /m2/noche. Sin embargo, los materiales&nbsp;variaron en la fracción del condensado escurrido desde las superficies, lo&nbsp;cual representa el agua disponible para las plántulas. Las fracciones de&nbsp;escorrentía más altas se obtuvieron con las superficies pintadas, seguido&nbsp;por las superficies de polietileno y de poli-olefina, respectivamente. Las&nbsp;cantidades de condensado durante el invierno fueron mayores que en&nbsp;verano, probablemente debido a noches más largas y menor nubosidad&nbsp;en invierno. Se evaluó el volumen de rocío (escorrentía) producido por un&nbsp;modelo comercial de condensador de rocío, el Groasis WaterboxxTM. Este&nbsp;nunca superó 0.04 L por noche, atribuido principalmente a la pequeña área&nbsp;de superficie (&lt; 0.2 m2) del condensador. Un experimento de campo mostró&nbsp;que condensadores de rocío de 1 m2 mantuvieron el potencial matricial&nbsp;de agua en la zona de raíces de plántulas de caoba en valores &gt; -60 kPa&nbsp;durante periodos de sequía. En general, los resultados indicaron que los&nbsp;condensadores de rocío con áreas superficiales de 1 m2 producen suficiente&nbsp;agua para la supervivencia de pequeñas plántulas de árboles

Asymptotically stable particle-in-cell methods for the Vlasov-Poisson system with a strong external magnetic field

International audienceThis paper deals with the numerical resolution of the Vlasov-Poissonsystem with a strong external magnetic field by Particle-In-Cell(PIC) methods. In this regime, classical PIC methods are subject tostability constraints on the time and space steps related to the smallLarmor radius and plasma frequency. Here, we propose anasymptotic-preserving PIC scheme which is not subjected to theselimitations. Our approach is based on first and higher order semi-implicit numericalschemes already validated on dissipative systems. Additionally, when the magnitude of the external magneticfield becomes large, this method provides a consistent PICdiscretization of the guiding-center equation, that is, incompressibleEuler equation in vorticity form. We propose several numerical experiments which provide a solid validation of the method and its underlying concepts

Controlling magnetic order and quantum disorder in molecule-based magnets.

We investigate the structural and magnetic properties of two molecule-based magnets synthesized from the same starting components. Their different structural motifs promote contrasting exchange pathways and consequently lead to markedly different magnetic ground states. Through examination of their structural and magnetic properties we show that [Cu(pyz)(H 2 O)(gly) 2 ](ClO 4 ) 2 may be considered a quasi-one-dimensional quantum Heisenberg antiferromagnet whereas the related compound [Cu(pyz)(gly)](ClO 4 ) , which is formed from dimers of antiferromagnetically interacting Cu 2+ spins, remains disordered down to at least 0.03 K in zero field but shows a field-temperature phase diagram reminiscent of that seen in materials showing a Bose-Einstein condensation of magnons