845 research outputs found
Holographic renormalization as a canonical transformation
The gauge/string dualities have drawn attention to a class of variational
problems on a boundary at infinity, which are not well defined unless a certain
boundary term is added to the classical action. In the context of supergravity
in asymptotically AdS spaces these problems are systematically addressed by the
method of holographic renormalization. We argue that this class of a priori ill
defined variational problems extends far beyond the realm of holographic
dualities. As we show, exactly the same issues arise in gravity in non
asymptotically AdS spaces, in point particles with certain unbounded from below
potentials, and even fundamental strings in flat or AdS backgrounds. We show
that the variational problem in all such cases can be made well defined by the
following procedure, which is intrinsic to the system in question and does not
rely on the existence of a holographically dual theory: (i) The first step is
the construction of the space of the most general asymptotic solutions of the
classical equations of motion that inherits a well defined symplectic form from
that on phase space. The requirement of a well defined symplectic form is
essential and often leads to a necessary repackaging of the degrees of freedom.
(ii) Once the space of asymptotic solutions has been constructed in terms of
the correct degrees of freedom, then there exists a boundary term that is
obtained as a certain solution of the Hamilton-Jacobi equation which
simultaneously makes the variational problem well defined and preserves the
symplectic form. This procedure is identical to holographic renormalization in
the case of asymptotically AdS gravity, but it is applicable to any Hamiltonian
system.Comment: 37 pages; v2 minor corrections in section 2, 2 references and a
footnote on Palatini gravity added. Version to appear in JHE
Heart Rhythm Monitoring Strategies for Cryptogenic Stroke: 2015 Diagnostics and Monitoring Stroke Focus Group Report.
No abstract available
Formation of Zn- and Fe-sulfides near hydrothermal vents at the Eastern Lau Spreading Center: implications for sulfide bioavailability to chemoautotrophs
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
Broad Spectrum Antiviral Activity of Favipiravir (T-705): Protection from Highly Lethal Inhalational Rift Valley Fever
Background:Development of antiviral drugs that have broad-spectrum activity against a number of viral infections would be of significant benefit. Due to the evolution of resistance to currently licensed antiviral drugs, development of novel anti-influenza drugs is in progress, including Favipiravir (T-705), which is currently in human clinical trials. T-705 displays broad-spectrum in vitro activity against a number of viruses, including Rift Valley Fever virus (RVFV). RVF is an important neglected tropical disease that causes human, agricultural, and economic losses in endemic regions. RVF has the capacity to emerge in new locations and also presents a potential bioterrorism threat. In the current study, the in vivo efficacy of T-705 was evaluated in Wistar-Furth rats infected with the virulent ZH501 strain of RVFV by the aerosol route.Methodology/Principal Findings:Wistar-Furth rats are highly susceptible to a rapidly lethal disease after parenteral or inhalational exposure to the pathogenic ZH501 strain of RVFV. In the current study, two experiments were performed: a dose-determination study and a delayed-treatment study. In both experiments, all untreated control rats succumbed to disease. Out of 72 total rats infected with RVFV and treated with T-705, only 6 succumbed to disease. The remaining 66 rats (92%) survived lethal infection with no significant weight loss or fever. The 6 treated rats that succumbed survived significantly longer before succumbing to encephalitic disease.Conclusions/Significance:Currently, there are no licensed antiviral drugs for treating RVF. Here, T-705 showed remarkable efficacy in a highly lethal rat model of Rift Valley Fever, even when given up to 48 hours post-infection. This is the first study to show protection of rats infected with the pathogenic ZH501 strain of RVFV. Our data suggest that T-705 has potential to be a broad-spectrum antiviral drug. © 2014 Caroline et al
The RR Lyrae Distance Scale
We review seven methods of measuring the absolute magnitude M_V of RR Lyrae
stars in light of the Hipparcos mission and other recent developments. We focus
on identifying possible systematic errors and rank the methods by relative
immunity to such errors. For the three most robust methods, statistical
parallax, trigonometric parallax, and cluster kinematics, we find M_V (at
[Fe/H] = -1.6) of 0.77 +/- 0.13, 0.71 +/- 0.15, 0.67 +/- 0.10. These methods
cluster consistently around 0.71 +/- 0.07. We find that Baade-Wesselink and
theoretical models both yield a broad range of possible values (0.45-0.70 and
0.45-0.65) due to systematic uncertainties in the temperature scale and input
physics. Main-sequence fitting gives a much brighter M_V = 0.45 +/- 0.04 but
this may be due to a difference in the metallicity scales of the cluster giants
and the calibrating subdwarfs. White-dwarf cooling-sequence fitting gives 0.67
+/- 0.13 and is potentially very robust, but at present is too new to be fully
tested for systematics. If the three most robust methods are combined with
Walker's mean measurement for 6 LMC clusters, V_{0,LMC} = 18.98 +/- 0.03 at
[Fe/H] = -1.9, then mu_{LMC} = 18.33 +/- 0.08.Comment: Invited review article to appear in: `Post-Hipparcos Cosmic Candles',
A. Heck & F. Caputo (Eds), Kluwer Academic Publ., Dordrecht, in press. 21
pages including 1 table; uses Kluwer's crckapb.sty LaTeX style file, enclose
Rotation of planet-harbouring stars
The rotation rate of a star has important implications for the detectability,
characterisation and stability of any planets that may be orbiting it. This
chapter gives a brief overview of stellar rotation before describing the
methods used to measure the rotation periods of planet host stars, the factors
affecting the evolution of a star's rotation rate, stellar age estimates based
on rotation, and an overview of the observed trends in the rotation properties
of stars with planets.Comment: 16 pages, 4 figures: Invited review to appear in 'Handbook of
Exoplanets', Springer Reference Works, edited by Hans J. Deeg and Juan
Antonio Belmont
Oceanic Sharks Clean at Coastal Seamount
Interactions between pelagic thresher sharks (Alopias pelagicus) and cleaner wrasse were investigated at a seamount in the Philippines. Cleaning associations between sharks and teleosts are poorly understood, but the observable interactions seen at this site may explain why these mainly oceanic sharks regularly venture into shallow coastal waters where they are vulnerable to disturbance from human activity. From 1,230 hours of observations recorded by remote video camera between July 2005 and December 2009, 97 cleaner-thresher shark events were analyzed, 19 of which were interrupted. Observations of pelagic thresher sharks interacting with cleaners at the seamount were recorded at all times of day but their frequency declined gradually from morning until evening. Cleaners showed preferences for foraging on specific areas of a thresher shark's body. For all events combined, cleaners were observed to conduct 2,757 inspections, of which 33.9% took place on the shark's pelvis, 23.3% on the pectoral fins, 22.3% on the caudal fin, 8.6% on the body, 8.3% on the head, 2.1% on the dorsal fin, and 1.5% on the gills respectively. Cleaners did not preferentially inspect thresher sharks by time of day or by shark sex, but there was a direct correlation between the amount of time a thresher shark spent at a cleaning station and the number of inspections it received. Thresher shark clients modified their behavior by “circular-stance-swimming,” presumably to facilitate cleaner inspections. The cleaner-thresher shark association reflected some of the known behavioral trends in the cleaner-reef teleost system since cleaners appeared to forage selectively on shark clients. Evidence is mounting that in addition to acting as social refuges and foraging grounds for large visiting marine predators, seamounts may also support pelagic ecology by functioning as cleaning stations for oceanic sharks and rays
Is a cooperative approach to seaweed farming effectual? An analysis of the seaweed cluster project (SCP), Malaysia
Seaweed (Kappaphycus spp.) farming has been practised in Malaysia since the late 1970s following government policy incentives (training and farming inputs). However, numerous governance, economic, environmental, technological and sociocultural challenges have limited the industry from achieving its full potential. The Seaweed Cluster Project (SCP) was introduced in 2012 to address some of these challenges. We sought to evaluate the effectiveness of the SCP in delivering its central objectives of increasing seaweed production, optimising the farming area, improving seaweed quality and farming efficiency, raising farmers’ income, and reducing the environmental impact of seaweed farming. Community and industry perceptions of the SCP were obtained from seven communities using a mixed-methods approach based on face-to-face semi-structured interviews, focus group discussions, household surveys, observation and secondary data. Views on the SCP outcomes were generally negative, including low take-up rates by indigenous people, poor stakeholder participation in decision-making, limited acceptance of new technologies, economic vulnerability, a complex marketing system, and low social cohesion of seaweed farming communities. Positive perceptions included recognition that the SCP confers high social status upon a community, reduces operating costs, and facilitates the production of certified seaweed. The SCP’s problems are linked to poor multi-level governance, weak market mechanisms and unintegrated community development. The study concludes with five recommendations to improve the SCP: promote the participation of indigenous people; legalise existing migrant farmers; strengthen local seaweed cooperative organisations; provide entrepreneurship skills to farmers; and fully integrate stakeholders into decision-making
Vectors Based on Modified Vaccinia Ankara Expressing Influenza H5N1 Hemagglutinin Induce Substantial Cross-Clade Protective Immunity
New highly pathogenic H5N1 influenza viruses are continuing to evolve with a potential threat for an influenza pandemic. So far, the H5N1 influenza viruses have not widely circulated in humans and therefore constitute a high risk for the non immune population. The aim of this study was to evaluate the cross-protective potential of the hemagglutinins of five H5N1 strains of divergent clades using a live attenuated modified vaccinia Ankara (MVA) vector vaccine.The replication-deficient MVA virus was used to express influenza hemagglutinin (HA) proteins. Specifically, recombinant MVA viruses expressing the HA genes of the clade 1 virus A/Vietnam/1203/2004 (VN/1203), the clade 2.1.3 virus A/Indonesia/5/2005 (IN5/05), the clade 2.2 viruses A/turkey/Turkey/1/2005 (TT01/05) and A/chicken/Egypt/3/2006 (CE/06), and the clade 2.3.4 virus A/Anhui/1/2005 (AH1/05) were constructed. These experimental live vaccines were assessed in a lethal mouse model. Mice vaccinated with the VN/1203 hemagglutinin-expressing MVA induced excellent protection against all the above mentioned clades. Also mice vaccinated with the IN5/05 HA expressing MVA induced substantial protection against homologous and heterologous AH1/05 challenge. After vaccination with the CE/06 HA expressing MVA, mice were fully protected against clade 2.2 challenge and partially protected against challenge of other clades. Mice vaccinated with AH1/05 HA expressing MVA vectors were only partially protected against homologous and heterologous challenge. The live vaccines induced substantial amounts of neutralizing antibodies, mainly directed against the homologous challenge virus, and high levels of HA-specific IFN-γ secreting CD4 and CD8 T-cells against epitopes conserved among the H5 clades and subclades.The highest level of cross-protection was induced by the HA derived from the VN/1203 strain, suggesting that pandemic H5 vaccines utilizing MVA vector technology, should be based on the VN/1203 hemagglutinin. Furthermore, the recombinant MVA-HA-VN, as characterized in the present study, would be a promising candidate for such a vaccine
A randomised controlled trial to evaluate the efficacy of a 6 month dietary and physical activity intervention for prostate cancer patients receiving androgen deprivation therapy
<p>Abstract</p> <p>Background</p> <p>Treatment with Androgen Deprivation Therapy (ADT) for prostate cancer is associated with changes in body composition including increased fat and decreased lean mass; increased fatigue, and a reduction in quality of life. No study to date has evaluated the effect of dietary and physical activity modification on the side-effects related to ADT. The aim of this study is to evaluate the efficacy of a 6-month dietary and physical activity intervention for prostate cancer survivors receiving ADT to minimise the changes in body composition, fatigue and quality of life, typically associated with ADT.</p> <p>Methods</p> <p>Men are recruited to this study if their treatment plan is to receive ADT for at least 6 months. Men who are randomised to the intervention arm receive a home-based tailored intervention to meet the following guidelines a) ≥ 5 servings vegetables and fruits/day; b) 30%-35% of total energy from fat, and < 10% energy from saturated fat/day; c) 10% of energy from polyunsaturated fat/day; d) limited consumption of processed meats; e) 25-35 gm of fibre/day; f) alcoholic drinks ≤ 28 units/week; g) limited intake of foods high in salt and/or sugar. They are also encouraged to include at least 30 minutes of brisk walking, 5 or more days per week. The primary outcomes are change in body composition, fatigue and quality of life scores. Secondary outcomes include dietary intake, physical activity and perceived stress. Baseline information collected includes: socio-economic status, treatment duration, perceived social support and health status, family history of cancer, co-morbidities, medication and supplement use, barriers to change, and readiness to change their health behaviour. Data for the primary and secondary outcomes will be collected at baseline, 3 and 6 months from 47 intervention and 47 control patients.</p> <p>Discussion</p> <p>The results of this study will provide detailed information on diet and physical activity levels in prostate cancer patients treated with ADT and will test the feasibility and efficacy of a diet and physical activity intervention which could provide essential information to develop guidelines for prostate cancer patients to minimise the side effects related to ADT.</p> <p>Trial registration</p> <p>ISRCTN trial number ISCRTN75282423</p
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