3,646 research outputs found
The first confirmation of V-type asteroids among the Mars crosser population
The Mars crossing region constitutes a path to deliver asteroids from the
Inner Main Belt to the Earth crossing space. While both the Inner Main Belt and
the population of Earth crossing asteroids contains a significant fraction of
asteroids belonging to the V taxonomic class, only two of such V-type asteroids
has been detected in the Mars crossing region up to now. In this work, we
searched for asteroids belonging to the V class among the population of Mars
crossing asteroids, in order to support alternative paths to the delivery of
this bodies into the Earth crossing region. We selected 18 candidate V-type
asteroids in the Mars crossing region using observations contained in the Sloan
Digital Sky Survey Moving Objects Catalog. Then, we observed 4 of these
candidates to take their visible spectra using the Southern Astrophysical
Research Telescope (SOAR). We also performed the numerical simulation of the
orbital evolution of the observed asteroids. We confirmed that 3 of the
observed asteroids belong to the V class, and one of these may follow a path
that drives it to an Earth collision in some tens of million years
Infrared spectroscopy of the largest known trans-neptunian object 2001 KX76
We report complete near-infrared (0.9-2.4 m) spectral observations of
the largest know trans-neptunian objects (TNO) 28976 = 2001 KX taken in
two different nights using the new Near Infrared Camera Spectrometer (NICS)
attached to the 3.56m Telescopio Nazionale Galileo (TNG). The spectra are
featureless and correspond to a neutral colored object. Our observations
indicate that the surface of 2001 KX is probably highly evolved due to
long term irradiation, and that collisional resurfacing processes have not
played an important role in its evolution.Comment: 1 Latex file, 2 postscript files. A&A in pres
In search of phylogenetic congruence between molecular and morphological data in bryozoans with extreme adult skeletal heteromorphy
peerreview_statement: The publishing and review policy for this title is described in its Aims & Scope. aims_and_scope_url: http://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=tsab20© Crown Copyright 2015. This document is the author's final accepted/submitted version of the journal article. You are advised to consult the publisher's version if you wish to cite from it
A new insight into the Galactic potential: a simple secular model for the evolution of binary systems in the solar neighbourhood
Context. Among the main effects that the Milky Way exerts in binary systems, the Galactic tide is the only one that is not probabilistic and can be deduced from a potential. Therefore, it is possible to perform an analysis of the global structure of the phase space of binary systems in the solar neighbourhood using the Galactic potential. Aims. The aim of this work is to obtain a simple model to study the collisionless dynamical evolution of generic wide binaries systems in the solar neighbourhood. Methods. Through an averaging process, we reduced the three-dimensional potential of the Galaxy to a secular one-degree of freedom model. The accuracy of this model was tested by comparing its predictions with numerical simulations of the exact equations of motion of a two-body problem disturbed by the Galaxy. Results. Using the one-degree of freedom model, we developed a detailed dynamical study, finding that the secular Galactic tide period changes as a function of the separation of the pair, which also gives a dynamical explanation for the arbitrary classification between wide and tight binaries. Moreover, the secular phase space for a generic gravitationally bound pair is similar to the dynamical structure of a Lidov-Kozai resonance, but surprisingly this structure is independent of the masses and semimajor axis of the binary system. Thus, the Galactic potential is able to excite the initially circular orbit of binary systems to high values of eccentricity, which has important implications for studies of binary star systems (with and without exoplanets), comets, and Oort cloud objects.Facultad de Ciencias AstronĂłmicas y GeofĂsica
Exploring the interdependencies of research funders in the UK
Investment in medical research is vital to the continuing improvement of the UK's health and wealth. It is through research that we expand our understanding of disease and develop new treatments for patients. Medical research charities currently contribute over ÂŁ1 billion annually to medical research in the UK, of which over ÂŁ350 million is provided by Cancer Research UK. Many charities,
including Cancer Research UK, receive no government funding for their research
activity.
Cancer Research UK is engaged in a programme of work in order to better understand the medical research funding environment and demonstrate the importance of sustained investment. A key part of that is the Office of Health
Economicsâ (OHE) 2011 report âExploring the interdependency between public and charitable medical researchâ. This study found that there are substantial
benefits, both financial and qualitative, from the existence of a variety of funders and that reductions in the level of government financial support for medical
research are likely to have broader negative effects.
This contributed to other evidence which found that the activities and funding of the charity, public and private sectors respectively are complementary, i.e. mutually reinforcing, rather than duplicative or merely substituting for one another.
âExploring the interdependencies of research funders in the UKâ by the Office of Health Economics (OHE) and SPRU: Science and Technology Policy Research at the University of Sussex, represents a continued effort to build the evidence base around the funding of medical research.
This report uncovers the extent to which funders of cancer research are interdependent, nationally and internationally. Key figures show that two
thirds of publications acknowledging external support have relied on multiple funders, while just under half benefited from overseas funding, and almost a fifth are also supported by industry. In addition the analysis
shows that the general public would not want tax funding of cancer research to be reduced, but would not donate enough to charities to compensate for any such reduction
Development of a Superconducting Twin Axis Cavity
Superconducting cavities with two separate accelerating axes have been proposed in the past for energy recovery linac applications. While the study showed the advantages of such cavity, the designs present serious fabrication challenges. Hence the proposed cavities have never been built. The new design, elliptical twin cavity, proposed by Jefferson Lab and optimized by Center for Accelerator Science at Old Dominion University, allows similar level of engineering and fabrication techniques of a typical elliptical cavity. This paper describes preliminary LOM and HOM spectrum, engineering and fabrication processes of the twin axis cavity
Rheological properties of the soft-disk model of two-dimensional foams
The soft-disk model previously developed and applied by Durian [D. J. Durian,
Phys. Rev. Lett. 75, 4780 (1995)] is brought to bear on problems of foam
rheology of longstanding and current interest, using two-dimensional systems.
The questions at issue include the origin of the Herschel-Bulkley relation,
normal stress effects (dilatancy), and localization in the presence of wall
drag. We show that even a model that incorporates only linear viscous effects
at the local level gives rise to nonlinear (power-law) dependence of the limit
stress on strain rate. With wall drag, shear localization is found. Its
nonexponential form and the variation of localization length with boundary
velocity are well described by a continuum model in the spirit of Janiaud et
al. [Phys. Rev. Lett. 97, 038302 (2006)]. Other results satisfactorily link
localization to model parameters, and hence tie together continuum and local
descriptions
Electromagnetic Design of a Superconducting Twin Axis Cavity
The twin-axis cavity is a new kind of rf superconducting cavity that consists of two parallel beam pipes, which can accelerate or decelerate two spatially separated beams in the same cavity. This configuration is particularly effective for high-current beams with low-energy electrons that will be used for bunched beam cooling of high-energy protons or ions. The new cavity geometry was designed to create a uniform accelerating or decelerating fields for both beams by utilizing a TM110 dipole mode. This paper presents the design rf optimization of a 1497 MHz twin-axis single-cell cavity, which is currently under fabrication
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