31,110 research outputs found
Probing the Low Surface Brightness Dwarf Galaxy Population of the Virgo Cluster
We have used public data from the Next Generation Virgo Survey (NGVS) to
investigate the dwarf galaxy population of the Virgo cluster beyond what has
previously been discovered. We initially mask and smooth the data, and then use
the object detection algorithm Sextractor to make our initial dwarf galaxy
selection. All candidates are then visually inspected to remove artefacts and
duplicates. We derive Sextractor parameters to best select low surface
brightness galaxies using g band central surface brightness values of 22.5 to
26.0 mag sq arc sec and exponential scale lengths of 3.0 - 10.0 arc sec to
identify 443 cluster dwarf galaxies - 303 of which are new detections. These
new detections have a surface density that decreases with radius from the
cluster centre. We also apply our selection algorithm to 'background',
non-cluster, fields and find zero detections. In combination, this leads us to
believe that we have isolated a cluster dwarf galaxy population. The range of
objects we are able to detect is limited because smaller scale sized galaxies
are confused with the background, while larger galaxies are split into numerous
smaller objects by the detection algorithm. Using data from previous surveys
combined with our data, we find a faint end slope to the luminosity function of
-1.35+/-0.03, which does not significantly differ to what has previously been
found for the Virgo cluster, but is a little steeper than the slope for field
galaxies. There is no evidence for a faint end slope steep enough to correspond
with galaxy formation models, unless those models invoke either strong feedback
processes or use warm dark matter.Comment: Accepted for publication in MNRA
UNICEF IWASH Project, Northern Region, Ghana : an adapted training manual for groundwater development
This report is an adapted training manual, with specific best practice recommendations for
groundwater development practitioners working in the Northern Region, Ghana. It is designed to
be used in conjunction with the existing comprehensive training manual ‘Developing
Groundwater: a guide to rural water supply’ by MacDonald, Davies, Calow and Chilton (2005).
The additional guidelines provided in this supplementary report are specific to the Northern
Region of Ghana, and have been informed by a review of groundwater development in the
region which BGS carried out on behalf of UNICEF in 2010-2011.
The Northern Region is a difficult area in which to find and develop groundwater resources. For
this reason, more resources – time and money – need to be focussed on careful borehole siting
and development in order to maximise success. This includes detailed desk and field
reconnaissance surveys; the effective use and interpretation of geophysical siting methods;
collection of good quality data during drilling and test pumping; rigorous recording and
management of data; and effective interpretation, sharing and use of hydrogeological
information by all groundwater development practitioners. This report, and the associated
manual ‘Developing Groundwater’, provide practical help for carrying out these activities
effectively.
The authors gratefully acknowledge those persons who contributed to the formation of these
guidelines, who include:
UNICEF Ghana – Othniel Habila, Kabuka Banda and David Ede
Community Water and Sanitation Agency (CWSA), Ghana – John Aduakye
Canadian International Development Agency (CIDA) – Hydrogeological Assessment
Project (HAP) – James Racicot
All participants at the UNICEF/BGS workshop and training programme held in Tamale,
Northern Region, from 7 to 18 February 2011
Cunning-folk in the medical market-place during the nineteenth century.
Copyright © Cambridge University Press 1999Over the last twenty years a considerable amount of valuable research has uncovered the activities of a variety of unorthodox medical practitioners in the eighteenth and nineteenth centuries. Quack doctors, spiritual healers, medical botanists, and bone-setters have all been subjected to detailed analysis. In contrast, the practitioners of folk-magical healing have been largely overlooked. This neglect of a significant sector of the nineteenth-century medical market-place is probably due to the nature of the relevant source material. Most of the information we have about cunning-folk derives from ethnographic sources and newspaper reports. The considerable body of folkloric material on cunning-folk has been particularly overlooked because of historians' general disregard for the anecdotal, and unsystematic way in which much of this information was gathered. However, when folkloric sources are examined in conjunction with the concrete data supplied in newspaper reports of the prosecution of cunning-folk, new light is cast on the popular experience of healing during the nineteenth century.3 The aim of the following discussion, therefore, is to introduce cunning-folk to the debate over medical provision in nineteenth-century society, and to examine their relationship with other groups of medical providers in terms of practice and public perceptionPeer reviewe
Electron-electron interactions in antidot-based Aharonov-Bohm interferometers
We present a microscopic picture of quantum transport in quantum antidots in
the quantum Hall regime taking electron interactions into account. We discuss
the edge state structure, energy level evolution, charge quantization and
linear-response conductance as the magnetic field or gate voltage is varied.
Particular attention is given to the conductance oscillations due to
Aharonov-Bohm interference and their unexpected periodicity. To explain the
latter we propose the mechanisms of scattering by point defects and Coulomb
blockade tunneling. They are supported by self-consistent calculations in the
Hartree approximation, which indicate pinning and correlation of the
single-particle states at the Fermi energy as well as charge oscillation when
antidot-bound states depopulate. We have also found interesting phenomena of
anti-resonance reflection of the Fano type.Comment: 12 pages, 8 figure
The Niger Delta and Human Rights in Nigeria
The Niger Delta Region in the enclave called Nigeria today has been terribly locked in an endless battle for its Human Rights which also includes the right to development and economic autonomy, with various predatory institutions which have across time, relentlessly sought to command its immense natural wealth and dictate to it the terms and manner of development it must follow. The world conference on Human Rights held in Vienna, Austria recognized the fact that development rights are arguably fundamental and inalienable rights. The recognition of the right to development and the meeting of basic economic and social needs as part of fundamental human rights by the conference marked a turning point in the United Nations recognition of only Civil rights as fundamental human rights.This paper takes a look at the Niger Delta , its problems of human rights to which development rights is a part and contends that the Niger Delta development rights must be promoted and defended at all cost on the basis of proper understanding of the institutionalization of a transparent and genuine democracy. KeyWords:*Niger Delta, *human rights, *development, *resource control, *Nigeria, *fundamental rights, *linternational la
Public ubiquitous computing systems:lessons from the e-campus display deployments
In this paper we reflect on our experiences of deploying ubiquitous computing systems in public spaces and present a series of lessons that we feel will be of benefit to researchers planning similar public deployments. We focus on experiences gained from building and deploying three experimental public display systems as part of the e-campus pro ject. However, we believe the lessons are likely to be generally applicable to many different types of public ubicomp deployment
Bir yabancı gözile İstanbul'un surları II
Taha Toros Arşivi, Dosya No: 122-Surlarİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033
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