66 research outputs found
Equilibrium configurations of two charged masses in General Relativity
An asymptotically flat static solution of Einstein-Maxwell equations which
describes the field of two non-extreme Reissner - Nordstr\"om sources in
equilibrium is presented. It is expressed in terms of physical parameters of
the sources (their masses, charges and separating distance). Very simple
analytical forms were found for the solution as well as for the equilibrium
condition which guarantees the absence of any struts on the symmetry axis. This
condition shows that the equilibrium is not possible for two black holes or for
two naked singularities. However, in the case when one of the sources is a
black hole and another one is a naked singularity, the equilibrium is possible
at some distance separating the sources. It is interesting that for
appropriately chosen parameters even a Schwarzschild black hole together with a
naked singularity can be "suspended" freely in the superposition of their
fields.Comment: 4 pages; accepted for publication in Phys. Rev.
The impact of land use/land cover scale on modelling urban ecosystem services
Context
Urbanisation places increasing stress on ecosystem services; however existing methods and data for testing relationships between service delivery and urban landscapes remain imprecise and uncertain. Unknown impacts of scale are among several factors that complicate research. This study models ecosystem services in the urban area comprising the towns of Milton Keynes, Bedford and Luton which together represent a wide range of the urban forms present in the UK.
Objectives
The objectives of this study were to test (1) the sensitivity of ecosystem service model outputs to the spatial resolution of input data, and (2) whether any resultant scale dependency is constant across different ecosystem services and model approaches (e.g. stock- versus flow-based).
Methods
Carbon storage, sediment erosion, and pollination were modelled with the InVEST framework using input data representative of common coarse (25 m) and fine (5 m) spatial resolutions.
Results
Fine scale analysis generated higher estimates of total carbon storage (9.32 vs. 7.17 kg m−2) and much lower potential sediment erosion estimates (6.4 vs. 18.1 Mg km−2 year−1) than analyses conducted at coarser resolutions; however coarse-scale analysis estimated more abundant pollination service provision.
Conclusions
Scale sensitivities depend on the type of service being modelled; stock estimates (e.g. carbon storage) are most sensitive to aggregation across scales, dynamic flow models (e.g. sediment erosion) are most sensitive to spatial resolution, and ecological process models involving both stocks and dynamics (e.g. pollination) are sensitive to both. Care must be taken to select model data appropriate to the scale of inquiry
Modelling the strategies for age specific vaccination scheduling during influenza pandemic outbreaks
Finding optimal policies to reduce the morbidity and mortality of the ongoing
pandemic is a top public health priority. Using a compartmental model with age
structure and vaccination status, we examined the effect of age specific
scheduling of vaccination during a pandemic influenza outbreak, when there is a
race between the vaccination campaign and the dynamics of the pandemic. Our
results agree with some recent studies on that age specificity is paramount to
vaccination planning. However, little is known about the effectiveness of such
control measures when they are applied during the outbreak. Comparing five
possible strategies, we found that age specific scheduling can have a huge
impact on the outcome of the epidemic. For the best scheme, the attack rates
were up to 10% lower than for other strategies. We demonstrate the importance
of early start of the vaccination campaign, since ten days delay may increase
the attack rate by up to 6%. Taking into account the delay between developing
immunity and vaccination is a key factor in evaluating the impact of
vaccination campaigns. We provide a general framework which will be useful for
the next pandemic waves as well
The novel antimicrobial peptide PXL150 in the local treatment of skin and soft tissue infections
Emerging concepts in biomarker discovery; The US-Japan workshop on immunological molecular markers in oncology
Supported by the Office of International Affairs, National Cancer Institute (NCI), the "US-Japan Workshop on Immunological Biomarkers in Oncology" was held in March 2009. The workshop was related to a task force launched by the International Society for the Biological Therapy of Cancer (iSBTc) and the United States Food and Drug Administration (FDA) to identify strategies for biomarker discovery and validation in the field of biotherapy. The effort will culminate on October 28th 2009 in the "iSBTc-FDA-NCI Workshop on Prognostic and Predictive Immunologic Biomarkers in Cancer", which will be held in Washington DC in association with the Annual Meeting. The purposes of the US-Japan workshop were a) to discuss novel approaches to enhance the discovery of predictive and/or prognostic markers in cancer immunotherapy; b) to define the state of the science in biomarker discovery and validation. The participation of Japanese and US scientists provided the opportunity to identify shared or discordant themes across the distinct immune genetic background and the diverse prevalence of disease between the two Nations
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