684 research outputs found
The hydrogeology of Northern Agago County in Pader District, Uganda
This report was produced to assist GOAL, an Irish NGO working in Uganda, in the provision
of water supplies for displaced persons in Agago County, part of Pader District in the north of
Uganda. The work contained within the report has been carried out on a voluntary basis,
although considerable support has been provided by GOAL in the provision of travel and
subsistence costs within Uganda, spanning the period from the 22nd September to the 12th
October 2007. Funding for preparatory work and for the writing of this report was provided
by the British Geological Survey (BGS).
The report describes the hydrogeology of five sub-counties (Lapono, Lukole, Paimol,
Parabongo and Wol) within Agago County, which cover GOALâs area of operation for water
and sanitation in Pader district. The area currently benefits from a large number of deep
boreholes, although many of these have proved to be dry at the time of drilling. GOAL aims
to meet the requirement for further water supplies largely through the provision of shallow,
hand-dug wells.
There has been no systematic geological or hydrogeological survey of the area to date and
geological maps are only available at scales of 1:1,000,000 and 1:1,250,000. Further data
collection during this visit has been restricted by limited exposures of rock, a lack of drill
cuttings and logistical difficulties arising from poor transport and continuing security
concerns. In general, however, the study area can be divided into areas of deeply weathered
crystalline basement and large inselbergs, exposing a range of high-grade metamorphic rocks.
Given the current emphasis on shallow well construction in the area, GIS layers of water
strike data and predicted depth to water have been created. The depth to the first recorded
water strikes appears to be largely controlled by the local topography and a map based on land
surface curvature (rate of change in slope) has been used to highlight topographic depressions
where water strikes are likely to be shallowest (negative curvature) and areas of raised ground
where water strikes may be more than 50 m below the surface (positive curvature). Where the
land surface curvature is below -0.001, recorded water strikes are uniformly within 40 m of
the surface. Where the land surface curvature is greater than this, however, the depth to water
strike is highly variable and recorded values range from 15 m to nearly 100 m below the
surface.
These results suggest that deep boreholes remain the most viable option for water supplies in
the majority of cases. While it is possible to highlight parts of the study area where water
strikes are likely to be shallowest, groundwater in these areas may still be more than 20 m
below the surface. As a result, shallow wells constructed in these areas would be unlikely to
succeed.
Overall aquifer productivity has also been assessed and the study area has been divided into
four domains with distinct hydrogeological characteristics. Transmissivity data from nearly
50 locations have been used in the delineation of these domains, along with topographic
considerations. The low-lying, flat land in the southwest is shown to contain the most
productive aquifers, while the areas close to the inselbergs in the north and east of the study
area are shown to have aquifers with low productivity.
The available data show no correlation between aquifer productivity and the depth of
weathering. This has implications for the continued use of resistivity surveys in identifying
suitable drilling sites, as much of the value of this technique lies in identifying the depth of
weathering
Defect flows in minimal models
In this paper we study a simple example of a two-parameter space of
renormalisation group flows of defects in Virasoro minimal models. We use a
combination of exact results, perturbation theory and the truncated conformal
space approach to search for fixed points and investigate their nature. For the
Ising model, we confirm the recent results of Fendley et al. In the case of
central charge close to one, we find six fixed points, five of which we can
identify in terms of known defects and one of which we conjecture is a new
non-trivial conformal defect. We also include several new results on exact
properties of perturbed defects and on the renormalisation group in the
truncated conformal space approach.Comment: 35 pages, 21 figures. 1 reference adde
Translocation t(11;18)(q21;q21) in gastric Bâcell lymphomas
Translocation t(11;18)(q21;q21) is the most frequent chromosomal aberration reported in gastric mucosa-associated lymphoid tissue (MALT) lymphomas. Intriguingly, this translocation has been reported only rarely in diffuse large B-cell lymphomas; it has been proposed that t(11;18)-positive tumors rarely progress to diffuse large B-cell lymphomas. We examined the frequency of chromosomal translocation t(11;18)(q21;q21) in mucosa-associated lymphoid tissue lymphoma and diffuse large B-cell lymphoma of the stomach. Paraffin-embedded tissues from patients with gastric B-cell lymphomas were selected retrospectively. The presence of the t(11;18)(q21;q21) was determined using reverse transcriptase-polymerase chain reaction and/or fluorescence in situ hybridization. beta-Actin transcript was also determined to evaluate the integrity and efficiency of RNA (cDNA) recovery from paraffin-embedded tissues. We analyzed 53 gastric B-cell lymphomas (33 diffuse large B-cell and 20 mucosa-associated lymphoid tissue) obtained from Italy, the USA, or Japan. Beta-actin transcript was amplified in 50 cases (94%), including 19 mucosa-associated lymphoid tissue and 31 diffuse large B-cell lymphomas (five with mucosa-associated lymphoid tissue components). The t(11;18) translocation was detected in 19% (6 of 31) cases with diffuse large B-cell lymphoma versus 26% (five of 19) with mucosa-associated lymphoid tissue lymphoma (P = 0.72). One of five diffuse large B-cell lymphomas with a mucosa-associated lymphoid tissue component showed the t(11;18)(q21;q21). In conclusion, translocation t(11;18)(q21;q21) was found in both mucosa-associated lymphoid tissue lymphomas and diffuse large B-cell lymphomas of the stomach at approximately equivalent frequencies; its presence does not exclude progression to diffuse large B-cell lymphoma
Positivity of energy for asymptotically locally AdS spacetimes
We derive necessary conditions for the spinorial Witten-Nester energy to be
well-defined for asymptotically locally AdS spacetimes. We find that the
conformal boundary should admit a spinor satisfying certain differential
conditions and in odd dimensions the boundary metric should be conformally
Einstein. We show that these conditions are satisfied by asymptotically AdS
spacetimes. The gravitational energy (obtained using the holographic stress
energy tensor) and the spinorial energy are equal in even dimensions and differ
by a bounded quantity related to the conformal anomaly in odd dimensions.Comment: 36 pages, 1 figure; minor corrections, JHEP versio
On the renormalisation group for the boundary Truncated Conformal Space Approach
In this paper we continue the study of the truncated conformal space approach
to perturbed boundary conformal field theories. This approach to perturbation
theory suffers from a renormalisation of the coupling constant and a
multiplicative renormalisation of the Hamiltonian. We show how these two
effects can be predicted by both physical and mathematical arguments and prove
that they are correct to leading order for all states in the TCSA system. We
check these results using the TCSA applied to the tri-critical Ising model and
the Yang-Lee model. We also study the TCSA of an irrelevant
(non-renormalisable) perturbation and find that, while the convergence of the
coupling constant and energy scales are problematic, the renormalised and
rescaled spectrum remain a very good fit to the exact result, and we find a
numerical relationship between the IR and UV couplings describing a particular
flow. Finally we study the large coupling behaviour of TCSA and show that it
accurately encompasses several different fixed points.Comment: 27 pages, 19 figure
Unpacking the Effect of Parental Monitoring on Early Adolescent Problem Behavior: Mediation by Parental Knowledge and Moderation by ParentâYouth Warmth
This study explores the monitoring process longitudinally among a sample of rural early adolescents and addresses two research questions: (a) Does maternal knowledge mediate the relationship between three aspects of the parental monitoring process and adolescent problem behavior: active parent monitoring efforts, youth disclosure, and parental supervision? (b) Are these meditational pathways moderated by the affective quality of the parentâchild relationship? Parent efforts to monitor youth and youth disclosure in the Fall of Grade 6 predicted substance use and delinquency in Grade 8. These relations were mediated by increases in maternal knowledge assessed in the Spring of Grade 6, suggesting that the protective effects of these constructs are partially indirect. Supervision was not significantly related to maternal knowledge or problem behavior. Parent efforts to monitor were more strongly related to maternal knowledge in families with high levels of positive affect than in families with low levels of positive affect
Conserved Charges in Even Dimensional Asymptotically locally Anti-de Sitter Space-times
Based on the recent paper hep-th/0503045, we derive a formula of calculating
conserved charges in even dimensional asymptotically {\it locally} anti-de
Sitter space-times by using the definition of Wald and Zoupas. This formula
generalizes the one proposed by Ashtekar {\it et al}. Using the new formula we
compute the masses of Taub-Bolt-AdS space-times by treating Taub-Nut-AdS
space-times as the reference solution. Our result agrees with those resulting
from "background subtraction" method or "boundary counterterm" method. We also
calculate the conserved charges of Kerr-Taub-Nut-AdS solutions in four
dimensions and higher dimensional Kerr-AdS solutions with Nut charges. The mass
of (un)wrapped brane solutions in any dimension is given.Comment: Latex, 28 pages, v2: minor changes, to appear in JHE
A serendipitous all sky survey for bright objects in the outer solar system
We use seven yearʌs worth of observations from the Catalina Sky Survey and the Siding Spring Survey covering most of the northern and southern hemisphere at galactic latitudes higher than 20° to search for serendipitously imaged moving objects in the outer solar system. These slowly moving objects would appear as stationary transients in these fast cadence asteroids surveys, so we develop methods to discover objects in the outer solar system using individual observations spaced by months, rather than spaced by hours, as is typically done. While we independently discover eight known bright objects in the outer solar system, the faintest having no new objects are discovered. We find that the survey is nearly 100% efficient at detecting objects beyond 25 AU for ( in the southern hemisphere) and that the probability that there is one or more remaining outer solar system object of this brightness left to be discovered in the unsurveyed regions of the galactic plane is approximately 32%
Holographic Description of Gravitational Anomalies
The holographic duality can be extended to include quantum theories with
broken coordinate invariance leading to the appearance of the gravitational
anomalies. On the gravity side one adds the gravitational Chern-Simons term to
the bulk action which gauge invariance is only up to the boundary terms. We
analyze in detail how the gravitational anomalies originate from the modified
Einstein equations in the bulk. As a side observation we find that the
gravitational Chern-Simons functional has interesting conformal properties. It
is invariant under conformal transformations. Moreover, its metric variation
produces conformal tensor which is a generalization of the Cotton tensor to
dimension . We calculate the modification of the holographic
stress-energy tensor that is due to the Chern-Simons term and use the bulk
Einstein equations to find its divergence and thus reproduce the gravitational
anomaly. Explicit calculation of the anomaly is carried out in dimensions
and . The result of the holographic calculation is compared with that of
the descent method and agreement is found. The gravitational Chern-Simons term
originates by Kaluza-Klein mechanism from a one-loop modification of M-theory
action. This modification is discussed in the context of the gravitational
anomaly in six-dimensional theory. The agreement with earlier
conjectured anomaly is found.Comment: 24 pages, Latex; presentation re-structured, new references adde
Topologically Massive Gravity and the AdS/CFT Correspondence
We set up the AdS/CFT correspondence for topologically massive gravity (TMG)
in three dimensions. The first step in this procedure is to determine the
appropriate fall off conditions at infinity. These cannot be fixed a priori as
they depend on the bulk theory under consideration and are derived by solving
asymptotically the non-linear field equations. We discuss in detail the
asymptotic structure of the field equations for TMG, showing that it contains
leading and subleading logarithms, determine the map between bulk fields and
CFT operators, obtain the appropriate counterterms needed for holographic
renormalization and compute holographically one- and two-point functions at and
away from the 'chiral point' (mu = 1). The 2-point functions at the chiral
point are those of a logarithmic CFT (LCFT) with c_L = 0, c_R = 3l/G_N and b =
-3l/G_N, where b is a parameter characterizing different c = 0 LCFTs. The bulk
correlators away from the chiral point (mu \neq 1) smoothly limit to the LCFT
ones as mu \to 1. Away from the chiral point, the CFT contains a state of
negative norm and the expectation value of the energy momentum tensor in that
state is also negative, reflecting a corresponding bulk instability due to
negative energy modes.Comment: 54 pages, v2: added comments and reference
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