3,374 research outputs found
Traversable wormholes: minimum violation of null energy condition revisited
It was argued in literature that traversable wormholes can exist with
arbitrarily small violation of null energy conditions. We show that if the
amount of exotic material near the wormhole throat tends to zero, either this
leads to a horn instead of a wormhole or the throat approaches the horizon in
such a way that infnitely large stresses develop on the throat.Comment: 12 pages. To appear in PR
On the Transfer of Metric Fluctuations when Extra Dimensions Bounce or Stabilize
In this report, we study within the context of general relativity with one
extra dimension compactified either on a circle or an orbifold, how radion
fluctuations interact with metric fluctuations in the three non-compact
directions. The background is non-singular and can either describe an extra
dimension on its way to stabilization, or immediately before and after a series
of non-singular bounces. We find that the metric fluctuations transfer
undisturbed through the bounces or through the transients of the
pre-stabilization epoch. Our background is obtained by considering the effects
of a gas of massless string modes in the context of a consistent 'massless
background' (or low energy effective theory) limit of string theory. We discuss
applications to various approaches to early universe cosmology, including the
ekpyrotic/cyclic universe scenario and string gas cosmology.Comment: V2. Minor Clarifications V3. appendix and 2 figures added, typos
corrected, conclusions unchanged 12 pages, 6 figure
High-energy effective theory for matter on close Randall Sundrum branes
Extending the analysis of hep-th/0504128, we obtain a formal expression for
the coupling between brane matter and the radion in a Randall-Sundrum
braneworld. This effective theory is correct to all orders in derivatives of
the radion in the limit of small brane separation, and, in particular, contains
no higher than second derivatives. In the case of cosmological symmetry the
theory can be obtained in closed form and reproduces the five-dimensional
behaviour. Perturbations in the tensor and scalar sectors are then studied.
When the branes are moving, the effective Newtonian constant on the brane is
shown to depend both on the distance between the branes and on their velocity.
In the small distance limit, we compute the exact dependence between the
four-dimensional and the five-dimensional Newtonian constants.Comment: Updated version as published in PR
Parental satisfaction with quality of health care of children with sickle cell disease at the University of Benin Teaching Hospital, Benin City
Background: Parents play a major role in determining where and when to access care for their children. Assessing parental satisfaction with the health system will be a pointer to attitude towards health institutions compliance with treatment and achievement of better treatment outcome, especially in the care of children with chronic diseases such as sickle cell disease (SCD). This study determined parental satisfaction with quality of health care of their children with SCD at the University of Benin Teaching Hospital (UBTH), Benin City.Methods: The study was a descriptive survey. A structured questionnaire with a five point Likert scale was used for data collection from parents of children with SCD. A mean score of 3.0 and above was used as an acceptable response for high level of satisfaction. The maximum allowable score was 5.Results: Parents of children with SCD had a good perception of the health facility with a high mean score of 4.35 ± 0.43. Parental satisfaction was high (mean score ranged from 3.49 ± 0.68 to 4.31 ± 0.50) across the entire construct. The highest and lowest levels of satisfaction was found in the domain “visit to the doctors (mean score was 4.31 ± 0.50) and “staff communication” (mean score 3.49 ± 0.68) respectively. Socio-demographic and economic factors did not significantly affect parental satisfaction with quality of health care.Conclusion: Parental satisfaction with quality of health care was high in this study. Areas with least level of satisfaction such as “communication with staff” and “care from the laboratory” should be reviewed for improvement.Keywords: Parental Satisfaction, Quality, Healthcare, Children, Sickle Cell Disease
Brane Cosmology in an Arbitrary Number of Dimensions
We derive the effective cosmological equations for a non-
symmetric codimension one brane embedded in an arbitrary D-dimensional bulk
spacetime, generalizing the cases much studied previously. As a
particular case, this may be considered as a regularized codimension (D-4)
brane avoiding the problem of curvature divergence on the brane. We apply our
results to the case of spherical symmetry around the brane and to partly
compactified AdS-Schwarzschild bulks.Comment: 23 page
Sustainable construction: a web-based performance assessment tool
The quest towards sustainable development, both nationally and globally, puts the
construction industry in the foreground as the main consumer of natural resources. The
industry has profound economic, social and environmental impacts. Sustainable
construction is one of the most important challenges faced by the construction industry
today. In the UK, sustainability is being driven and enforced by the government through
stringent fiscal policies and regulations, voluntary initiatives combined with naming and
shaming strategies. Stakeholders are becoming more aware of the global challenges and
are using their power to exert pressure on companies. Increasingly, construction clients
are demanding that their business partners submit: their corporate sustainability policies
with tender packages to demonstrate their performance in dealing with opportunities
and risks stemming from economic, environmental and social aspect of sustainability.
However, the lack of understanding of the concept and its practical application has been
a recurrent problem.
The conceptual confusion; its vagueness and ambiguity, the complexity of the myriad of
challenges and fluidity of the sustainability concept, compounded with the myopic
attitude of the industry, lack of clear-cut and practical framework are causing frustration
in the construction industry. Consequently, a number of sustainability management
frameworks have been proposed. There are probably more than one hundred
frameworks for sustainable business strategy. However, the majority of these are either
complicated to implement or lack sound theoretical base, effective change management
and completeness. These, therefore, do not make the situation any easier. Many are still
baffled as to what they should do and how they should go about affecting change. Corporate sustainability in the construction industry is a challenge to many companies.
The industry is still under-performing in each of the key themes of sustainable
construction and this has lead to a 'blame culture’ where each sector of the industry
allocates responsibility for its current failings to others (CIRIA C563, 2001). Such a
situation poses a need for a comprehensive, practical and easy to use tool that would aid
the implementation and management of sustainability at the core of business process.
The tool will complement the existing frameworks, which breaks down the strategic and
management issues into manageable components. This will enable companies to focus
on individual areas and identify actions needed to facilitate change. The problem is that
such a tool is virtually non-existent.
The main focal point of this research is the development of a tool to facilitate the
implementation, management and integration of sustainability issues at the strategic
level and promote wider uptake of the concept in the construction industry. This
requires a thorough understanding of the concepts of sustainable development,
sustainable construction and related issues as well as drivers, benefits, barriers and
enablers for achieving corporate sustainability. It also demands an examination of
existing management frameworks and collation of case studies from the early adopters
to establish critical factors for strategic and management issues involved in achieving
corporate sustainability. Through, diverse research epistemologies (quantitative,
qualitative and triangulation methods), the research established four main critical factors
and thirty-six sub-critical factors for achieving corporate sustainability. These factors
underpinned the development of a web-based prototype software (ConPass). This thesis
presents the development and evaluation ConPass Model and the prototype software
Critical current density and ac harmonic voltage generation in thin films by the screening technique
The temperature and field dependence of harmonics in voltage
using the screening technique have been measured for
superconducting
thin films. Using the Sun model we obtained the curves for the
temperature-dependent critical current density . In addition, we
applied the criterion proposed by Acosta et al. to compute . Also, we
made used of the empirical law as an input in our
calculations to reproduce experimental harmonic generation up to the fifth
harmonic. We found that most models fit well the fundamental voltage but higher
harmonics are poorly reproduced. Such behavior suggests the idea that higher
harmonics contain information concerning complex processes like flux creep or
thermally assisted flux flow.Comment: 2 pages, 2 figure
Measuring the Welfare Impact of Public Expenditure on Primary Healthcare Services in Rural Nigeria: A Benefit-Incidence Approach
In this study, attempt has been made to measure the welfare impact of government expenditure on primary healthcare services in rural Nigeria employing the benefit-incidence approach. To do this data were generated from the various healthcare centres located in Ika South Local Government Area from a combination of primary and secondary sources. On the basis of the sample selected, households were decomposed into non-poor, moderately poor and core poor. An analysis of the data generated depicts that the non-poor benefited more from the public primary healthcare services. The low benefit accruing to the poor group is attributable to their relative inaccessibility to access public healthcare in terms of drugs and consultatison. There is therefore the need for proper implementation of primary healthcare policies to make them more pro-poor. In this regard, this paper recommends that local governments should collaborate with community for drug revolving scheme. This is to enable the poor in the rural areas have more access to genuine drug at affordable price. Most importantly, there should be restructuring in public health expenditure pattern, focusing more on primary healthcare since this will benefit more of the poor and vulnerable in the society. By so doing, their welfare would be greatly improved. Keywords: Public expenditure on healthcare services, welfare impact, benefit-incidence analysis JEL classification: C2; C3; E
An Empirical Analysis of the Distributional Impact of Public Expenditure Pattern on Human Development in Nigeria States
This study is to empirically analyze the distributional impact of public expenditure pattern on human development using data for 20 states in Nigeria for the period, 1996-2012. Based on the results of fixed-effects model, the analysis reveals that the effect of sectoral changes in public expenditure on human development differs. While a change in education, health, agriculture, rural development and water resources expenditure has an increasing effect, a change in energy and housing expenditure has a decreasing effect on human development. In all, the estimated coefficient reveals that public expenditure has not robustly impacted on human development across states and period covered by the study. It is therefore recommended that it is imperative for the states to improve and sustain human development expenditure focusing more on education, health, agriculture, rural development and portable water resources since they have positive marginal impact on human development. Moreover, states in Nigeria should develop an expenditure framework for equitable human development expenditure that would benefit all in the near future. More importantly, there is urgent need for reform in expenditure pattern among states in Nigeria. This is to ensure that more money is allocated to those sectors that have higher capabilities of fostering human development. Keywords: Public expenditure; Human development; Panel data; fixed effec
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