8,789 research outputs found
The first total synthesis of (+)-mucosin
The first total synthesis of (+)-mucosin has been completed allowing assignment of the absolute stereochemistry of the natural product. A zirconium induced co-cyclisation was utilised to install the correct stereochemistry of the four contiguous stereocentres around the unusual bicyclo[4.3.0]nonene core
Explicit Formulas for Relaxed Disarrangement Densities Arising from Structured Deformations
Structured deformations provide a multiscale geometry that captures the
contributions at the macrolevel of both smooth geometrical changes and
non-smooth geometrical changes (disarrangements) at submacroscopic levels. For
each (first-order) structured deformation of a continuous body, the
tensor field is known to be a measure of deformations without
disarrangements, and is known to be a measure of deformations
due to disarrangements. The tensor fields and together deliver not only
standard notions of plastic deformation, but and its curl deliver the
Burgers vector field associated with closed curves in the body and the
dislocation density field used in describing geometrical changes in bodies with
defects. Recently, Owen and Paroni [13] evaluated explicitly some relaxed
energy densities arising in Choksi and Fonseca's energetics of structured
deformations [4] and thereby showed: (1) , the positive part of
, is a volume density of disarrangements due to submacroscopic
separations, (2) , the negative part of , is a volume density
of disarrangements due to submacroscopic switches and interpenetrations, and
(3) , the absolute value of , is a volume density of all three of
these non-tangential disarrangements: separations, switches, and
interpenetrations. The main contribution of the present research is to show
that a different approach to the energetics of structured deformations, that
due to Ba\'ia, Matias, and Santos [1], confirms the roles of ,
, and established by Owen and Paroni. In doing so, we give
an alternative, shorter proof of Owen and Paroni's results, and we establish
additional explicit formulas for other measures of disarrangements.Comment: 17 pages; http://cvgmt.sns.it/paper/2776
\u3cem\u3eChlamydomonas\u3c/em\u3e mutants display reversible deficiencies in flagellar beating and axonemal assembly
Axonemal complexes in flagella are largely prepackaged in the cell body. As such, one mutation often results in the absence of the co-assembled components and permanent motility deficiencies. For example, a Chlamydomonas mutant defective in RSP4 in the radial spoke (RS), which is critical for bend propagation, has paralyzed flagella that also lack the paralogue RSP6 and three additional RS proteins. Intriguingly, recent studies showed that several mutant strains contain a mixed population of swimmers and paralyzed cells despite their identical genetic background. Here we report a cause underlying these variations. Two new mutants lacking RSP6 swim processively and other components appear normally assembled in early log phase indicating that, unlike RSP4, this paralogue is dispensable. However, swimmers cannot maintain the typical helical trajectory and reactivated cell models tend to spin. Interestingly the motile fraction and the spokehead content dwindle during stationary phase. These results suggest that (1) intact RS is critical for maintaining the rhythm of oscillatory beating and thus the helical trajectory; (2) assembly of the axonemal complex with subtle defects is less efficient and the inefficiency is accentuated in compromised conditions, leading to reversible dyskinesia. Consistently, several organisms only possess one RSP4/6 gene. Gene duplication in Chlamydomonas enhances RS assembly to maintain optimal motility in various environments
The unavoidable costs of ethnicity : a review of evidence on health costs
This report was commissioned by the Advisory Committee on Resource Allocation (ACRA), and prepared
by the Centre for Health Services Studies (CHESS) and the Centre for Research in Ethnic Relations
(CRER) at the University of Warwick. The NHS Executive does not necessarily assent to the factual
accuracy of the report, nor necessarily share the opinions and recommendations of the authors.
The study reviews the evidence concerning the degree to which the presence of populations of minority
ethnic origin was associated with ‘unavoidable additional costs’ in health service delivery. While local
health authorities retail full autonomy in their use of funds allocated to them under the Hospital and
Community Health Services formula, the size of that budget is governed by a set of weightings applied to
their population, to allow for factors known to influence levels of need, and the costs of providing services.
The study began by considering the definitions used in describing ‘ethnicity’ and ethnic groups in relevant
medical and social policy literature. It is clear that no fixed set of terms can be adopted, and that flexibility
is required to respond to social changes. The terms used in the 1991 Census, with additions to allow for
local and contemporary developments, provide a suitable baseline but require additional information on
religion language and migration history for clinical and health service delivery planning.
There have been notable developments in health service strategy to meet the needs of black and minority
ethnic groups which have been encouraged by good practice guidelines and local initiatives. Together with
research into epidemiology and ethnic monitoring of services, these have enlarged understanding of the
impact of diversity. A conceptual model is developed which explores the potential for such diversity to lead
to variations in the cost of providing health services to a multi-ethnic population.
The research team reviewed the existing published evidence relating to ethnic health and disease treatment
in medical, social science, academic and practitioner literature, using conventional techniques. Additional
evidence was located through trawls of ‘grey’ literature in specialist collections, and through contacting all
English health districts with a request for information. A number of authorities and trusts provided written
and oral evidence, and a bibliography of key materials is provided.
Key issues considered include the need for and use of, interpreter and translation services, the incidence of
‘ethnically-specific’ disease, and variations in the prevalence and cost of treating ‘common’ conditions in
minority ethnic populations. Sources of variation are discussed, and a ‘scoping’ approach adopted to
explore the extent to which these variations could be adequately modelled. It is clear that while some
additional costs can be identified, and seen to be unavoidable, there are other areas where the presence of
minority populations may lead to lessened pressures on budgets, or where provision of ‘ethnic-specific’
facilities may be alternative to existing needs.
The literature provides a range of estimates which can be used in a modelling exercise, but is deficient in
many respects, particularly in terms of precise costs associated with procedure and conditions, or in
associating precise and consistent categories of ethnic group with epidemiological and operational service
provision data. Certain other activities require funding to set them up, and may not be directly related to
population size. There is considerable variation in the approaches adopted by different health authorities,
and many services are provided by agencies not funded by NHS budgets. The study was completed before
the announcement of proposed changes in health service commissioning which may have other implications
for ethnic diversity.
The presence of minorities is associated with the need to provide additional services in respect of
interpreting and translation, and the media of communication.
In order to achieve clinical effectiveness, a range of advocacy support facilities or alternative models of
provision seem to be desirable.
Ethnic diversity requires adaptation and additional evidence in order to inform processes of consultation
and commissioning.
Minority populations do create demands for certain additional specific clinical services not required by the
bulk of the majority population: it is not yet clear to what extent the reverse can be stated since research on
‘under-use’ is less well developed.
Some variations in levels of need, particularly those relating to established clinical difference in
susceptibility or deprivation, are already incorporated in funding formulae although it is not clear how far
the indicators adequately reflect these factors.
Costs are not necessarily simply related to the size of minority populations.
The provision of services to meet minority needs is not always a reflection of their presence, but has
frequently depended upon the provision of additional specific funds.
There is a consensus that the NHS research and development strategy should accept the need for more work
to establish the actual levels of need and usage of service by ethnic minority groups, and that effort should
be made to use and improve the growing collection of relevant information through ethnic monitoring
activities.
A variety of modelling techniques are suggested, and can be shown to have the potential to provide
practical guidance to future policy in the field.
Current data availability at a national or regional scale is inadequate to provide estimates of the ‘additional
costs of ethnicity’ but locally collected data and the existence of relevant policy initiatives suggest that a
focused study in selected districts would provide sufficiently robust information to provide reliable
estimates.
The review has demonstrated that there are costs associated with the presence of minority ethnic groups in
the population which can be shown to be unavoidable and additional, but that others are either ‘desirable’ or
‘alternative’. It would be wrong to assume that all cost pressures of this nature are in the same direction.
Our study has drawn attention to deficiencies in data collection and budgeting which may hinder
investigation of the effectiveness of the service in general. The process of drawing attention to ethnic
minority needs itself leads to developments in services which are functional and desirable for the majority
population
Prevalence of traumatic brain injury amongst children admitted to hospital in one health district : a population-based study
There is a dearth of information regarding the prevalence of brain injury, serious enough to require hospital admission, amongst children in the United Kingdom. In North Staffordshire a register of all children admitted with traumatic brain injury (TBI) has been maintained since 1992 presenting an opportunity to investigate the incidence of TBI within the region in terms of age, cause of injury, injury severity and social deprivation. The register contains details of 1553 children with TBI, two thirds of whom are male. This population-based study shows that TBI is most prevalent amongst children from families living in more deprived areas, however, social deprivation was not related to the cause of injury. Each year, 280 per 100,000 children are admitted for ≥24 hours with a TBI, of these 232 will have a mild brain injury, 25 moderate, 17 severe, and 2 will die. The incidence of moderate and severe injuries is higher than previous estimates. Children under 2 years old account for 18.5% of all TBIs, usually due to falls, being dropped or non-accidental injuries. Falls account for 60% of TBIs in the under 5s. In the 10-15 age group road traffic accidents were the most common cause (185, 36.7%). These findings will help to plan health services and target accident prevention initiatives more accurately
Past and Present Large Solid Rocket Motor Test Capabilities
A study was performed to identify the current and historical trends in the capability of solid rocket motor testing in the United States. The study focused on test positions capable of testing solid rocket motors of at least 10,000 lbf thrust. Top-level information was collected for two distinct data points plus/minus a few years: 2000 (Y2K) and 2010 (Present). Data was combined from many sources, but primarily focused on data from the Chemical Propulsion Information Analysis Center s Rocket Propulsion Test Facilities Database, and heritage Chemical Propulsion Information Agency/M8 Solid Rocket Motor Static Test Facilities Manual. Data for the Rocket Propulsion Test Facilities Database and heritage M8 Solid Rocket Motor Static Test Facilities Manual is provided to the Chemical Propulsion Information Analysis Center directly from the test facilities. Information for each test cell for each time period was compiled and plotted to produce a graphical display of the changes for the nation, NASA, Department of Defense, and commercial organizations during the past ten years. Major groups of plots include test facility by geographic location, test cells by status/utilization, and test cells by maximum thrust capability. The results are discussed
Case Commentary: Comparative Negligence in a Maritime Products Liability Case - Lewis v. Timco, Inc.
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