2,569 research outputs found
Energy distribution of charged dilaton black holes
Chamorro and Virbhadra studied, using the energy-momentum complex of
Einstein, the energy distribution associated with static spherically symmetric
charged dilaton black holes for an arbitrary value of the coupling parameter
which controls the strength of the dilaton to the Maxwell field. We
study the same in Tolman's prescription and get the same result as obtained by
Chamorro and Virbhadra. The energy distribution of charged dilaton black holes
depends on the value of and the total energy is independent of this
parameter.Comment: 8 pages, RevTex, no figure
Petrology of the zoned, peraluminous Halifax Pluton, south-central Nova Scotia
The Halifax Pluton (HP) is a large (approximately 900 km2 ), discrete plutonic body which forms the southeastern end of the South Mountain Batholith (SMB). The HP comprises a zoned sequence of rocfc units into which a second, generally more evolved sequence of rocks was intruded. Rocks of the zoned sequence are predominantly medium- to coarse-grained, have megacrystic textures, are generally monzogranltic In composition (with minor granodiorite) and have biotite (4-15%), muecovite (trace-4%) and cordlerlte (0->4%) as essential constituents. The second sequence is primarily fine-to medium-grained with highly variable textures (e.g., porphyrltic, equigranular, graphic), is generally monzogranltic in composition with minor leucogranite (<2% mafic minerals) and syenogranite, and have muscovite (2-10%), biotite (0-8%) and cordlerlte (0-2%) as essential minerals. Andalusite, generally absent from the zoned sequence, is commonly present as an accessory phase. Contacts between the two sequences are invariably intrusive.
Petrographlc and geochemical evidence suggests that the outer segment of the zoned sequence is normally zoned (i.e., more evolved toward the core). This may be explained by sidewall crystallization in a magma chamber with the removal of plagloclase and biotite (with accessory zircon, monazlte. xenotLme, apatite and ilmenite). Conversely, the inner portion of the pluton Is reversely zoned (i.e., less evolved toward core with an increase in biotite) which cannot be explained by fractional crystallization. Therefore, a model involving vertical stratification in the melt is proposed.
The presence of the zoned arrangement of rock units coupled with high contents of MgO, P2O5 and normative corundum, enstatite, hypersthene, apatite and high modal amounts of cordlerlte compared with the central SMB suggest that the H? evolved as a discrete pluton.
RÉSUMÉ
Le pluton de Halifax (PH) est un bâti plutonique distinct de grande taille (environ 900 km 2) qui constitue l'extreraité sud-est du Batholite de South Mountain (BSM). Le PH comprend une série d'unités rocheuses zonée à travers laquelle s'est injectée une seconde série de rocbes généralement plus évoluée. Lea terroes de la série zonee montrent surtout un grain intermédiaire à grossier ainsi que des textures mégacristes et ont généralement une composition monzogranltlque (avec quelque granodiorite). Lea constituents essentiels en sont la biotite (4-15%), la muscovite (trace -4%) et la cordlerlte (0->4%). La seconde série présente un grain surtout fin à intermédiaire. exhibe des textures varices (e.g., porphlrique, grenue, graphlque) et possede une composition généralement monzogranltlque avec quelque leucogranite (minéraux mafiques 2%) et syenogranite. Ses minéraux essentiels sont la muscovite (2-10%), la biotite (0-8%) et la cordlerlte (0-2%). Bien que généralement absente de la éerie zonee, l'andalousite formé éonmunement une phase accessoire. Les contacts entre les deux series sont invariablement intrusifs.
À la lumière de la pétrographie et la géochimie, le liseré de la série zonée semble zone normalement (i.e., plus évolue vers le coeur). Ceci peut s'expliquer par la cristallisation des épontes de la chambre raagmatique et l’elimination du plagloclase et de la biotite (avec les zircon, monazite, xénotime, apatite et ilménite). Par contre, la portion interne du pluton montre une zonation inverse (i.e., moins évoluée vers le coeur avec une augmentation de la biotite) qui ne peut s'éxpliquer par la cristallisation frectionnée. On propose done un modèle necessitant une stratification verticale du bain.
La présence d'une zonation des unites rocheuses combinée aux contenus élevés de MgO, P2O5 corindon normative, enstatite, hypersthene, apatite ainsi qu'aux valeurs modèles élevées de la cordleite, par rapport à la portion centrale du BSM suggèrent que le PH a évolué en tant que pluton distinct.
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Escaping the pushpin paradigm in geographic information science: (re)presenting national crime data
In 2011 the Home Office released the police.uk website, which provided a high-resolution map of recent
crime data for the national extents of England, Wales and Northern Ireland. Through this free service,
crimes were represented as points plotted on top of a Google map, visible down to a street level of
resolution. However, in order to maintain confidentiality and to comply with data disclosure legislation,
individual-level crimes were aggregated into points that represented clusters of events that were located
over a series of streets. However, with aggregation the representation of crimes as points becomes
problematic, engendering spurious precision over where crimes occurred. Given obvious public sensitivity
to such information, there are social imperatives for appropriate representation of crime data, and
as such, in this paper we present a method of translating the ‘point’ crime events into a new representational
form that is tied to street network geography; presenting these results in an alternate national
crime mapping portal http://www.policestreets.co.u
Denying humanness to victims: How gang members justify violent behavior
The high prevalence of violent offending amongst gang-involved youth has been established in the literature. Yet the underlying psychological mechanisms that enable youth to engage in such acts of violence remain unclear. 189 young people were recruited from areas in London, UK, known for their gang activity. We found that gang members, in comparison to non-gang youth, described the groups they belong to as having recognized leaders, specific rules and codes, initiation rituals, and special clothing. Gang members were also more likely than non-gang youth to engage in violent behavior and endorse moral disengagement strategies (i.e., moral justification, euphemistic language, advantageous comparison, displacement of responsibility, attribution of blame, and dehumanization). Finally, we found that dehumanizing victims partially mediated the relationship between gang membership and violent behavior. These findings highlight the effects of groups at the individual level and an underlying psychological mechanism that explains, in part, how gang members engage in violence
Impacts of Water and Sanitation Activities on the Environment in the Upper Mara Basin
The provision of reliable and safe water supplies is an essential element in improving the quality of life for mankind. However, over time the natural resource base has become severely stressed due to unsustainable use of the resources. This study was undertaken to evaluate the impacts of water, sanitation and hygiene (WASH) activities on the environment in the upper Mara River basin. Sampled water and sanitation projects were identified by observation and Geographic Information System (GIS) was used to map and report on these projects. Impacts of the projects on land and environmental quality were assessed using Land Quality Indicators (LQI); fresh water quality, solid and liquid waste generation and management and soil erosion. Water samples were analyzed for physical, chemical and bacteriological parameters and only 23.4% of sampled water sources were found suitable as domestic water sources. Most open water sources were contaminated with E. Coli caused by open defecation in the basin which on average was 38%. The study showed that, 21.3% of the sampled water supply projects had evidence of soil erosion around them which was mainly caused by livestock overcrowding at water points. Among the wastewater generating and management activities in upper Mara basin, Bomet municipal stabilization pond posed the greatest pollution threat to the environment since it lacked capacity to treat waste water to standards before it overflowed into the environment. This study recommended that WASH project implementers, users and managers should plan for and implement environmentally sustainable projects. In addition, WASH stakeholders in the basin should make comprehensive efforts to provide improved water sources and sanitation to all the residents. Keywords: Water, Sanitation, Environment, Impact
Time-dependent Hamiltonian estimation for Doppler velocimetry of trapped ions
The time evolution of a closed quantum system is connected to its Hamiltonian
through Schroedinger's equation. The ability to estimate the Hamiltonian is
critical to our understanding of quantum systems, and allows optimization of
control. Though spectroscopic methods allow time-independent Hamiltonians to be
recovered, for time-dependent Hamiltonians this task is more challenging. Here,
using a single trapped ion, we experimentally demonstrate a method for
estimating a time-dependent Hamiltonian of a single qubit. The method involves
measuring the time evolution of the qubit in a fixed basis as a function of a
time-independent offset term added to the Hamiltonian. In our system the
initially unknown Hamiltonian arises from transporting an ion through a static,
near-resonant laser beam. Hamiltonian estimation allows us to estimate the
spatial dependence of the laser beam intensity and the ion's velocity as a
function of time. This work is of direct value in optimizing transport
operations and transport-based gates in scalable trapped ion quantum
information processing, while the estimation technique is general enough that
it can be applied to other quantum systems, aiding the pursuit of high
operational fidelities in quantum control.Comment: 10 pages, 8 figure
Computer simulation of Wheeler's delayed choice experiment with photons
We present a computer simulation model of Wheeler's delayed choice experiment
that is a one-to-one copy of an experiment reported recently (V. Jacques {\sl
et al.}, Science 315, 966 (2007)). The model is solely based on experimental
facts, satisfies Einstein's criterion of local causality and does not rely on
any concept of quantum theory. Nevertheless, the simulation model reproduces
the averages as obtained from the quantum theoretical description of Wheeler's
delayed choice experiment. Our results prove that it is possible to give a
particle-only description of Wheeler's delayed choice experiment which
reproduces the averages calculated from quantum theory and which does not defy
common sense.Comment: Europhysics Letters (in press
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