1,592 research outputs found
The Holobiont Imperative: perspectives from early emerging animals
This book examines how the growing knowledge of the huge range of animal-bacterial interactions, whether in shared ecosystems or intimate symbioses, is fundamentally altering our understanding of animal biology. Individuals from simple invertebrates to human are not solitary, homogenous entities but consist of complex communities of many species that likely evolved during a billion years of coexistence. Defining the individual microbe-host conversations in these consortia, is a challenging but necessary step on the path to understanding the function of the associations as a whole. The hologenome theory of evolution considers the holobiont with its hologenome as a unit of selection in evolution. This new view may have profound impact on understanding a strictly microbe/symbiont-dependent life style and its evolutionary consequences. It may also affect the way how we approach complex environmental diseases from corals (coral bleaching) to human (inflammatory bowel disease etc). The book is written for scientists as well as medically interested persons in the field of immunobiology, microbiology, evolutionary biology, evolutionary medicine and corals
Non-compact QED(3) coupled to a four-fermi interaction
We present preliminary numerical results for the three dimensional
non-compact QED with a weak four-fermion term in the lattice action. Approaches
based on Schwinger-Dyson studies, arguments based on thermodynamic inequalities
and numerical simulations lead to estimates of the critical number of fermion
flavors (below which chiral symmetry is broken) ranging from to
. The weak four-fermion coupling provides the framework for an
improved algorithm, which allows us to simulate the chiral limit of massless
fermions and expose delicate effects.Comment: 3 pages, Contribution to Lattice2004(chiral), Fermilab, June 21-26,
200
Classification of Generalized Symmetries for the Vacuum Einstein Equations
A generalized symmetry of a system of differential equations is an
infinitesimal transformation depending locally upon the fields and their
derivatives which carries solutions to solutions. We classify all generalized
symmetries of the vacuum Einstein equations in four spacetime dimensions. To
begin, we analyze symmetries that can be built from the metric, curvature, and
covariant derivatives of the curvature to any order; these are called natural
symmetries and are globally defined on any spacetime manifold. We next classify
first-order generalized symmetries, that is, symmetries that depend on the
metric and its first derivatives. Finally, using results from the
classification of natural symmetries, we reduce the classification of all
higher-order generalized symmetries to the first-order case. In each case we
find that the generalized symmetries are infinitesimal generalized
diffeomorphisms and constant metric scalings. There are no non-trivial
conservation laws associated with these symmetries. A novel feature of our
analysis is the use of a fundamental set of spinorial coordinates on the
infinite jet space of Ricci-flat metrics, which are derived from Penrose's
``exact set of fields'' for the vacuum equations.Comment: 57 pages, plain Te
Lensing in an interior Kottler solution
We derive the interior Kottler solution of the incompressible fluid and show
that the bending of light in this solution does depend on the cosmological
constant.Comment: The inner Kottler solution derived and used in this paper is not new.
Corresponding references to Stuchlik (2000) and Boehmer (2003) are added.
Also added: a numerical example and a figure. This is the version accepted by
Gen. Rel. Grav. However it includes a short passage that an anonymous referee
had me suppress
Aquifer simulation model for use on disk supported small computer systems
Includes bibliographical references (p. 21).Cover title
D-brane dynamics near compactified NS5-branes
We examine the dynamics of a -brane in the background of coincident,
parallel 5-branes which have had one of their common transverse directions
compactified. We find that for small energy, bound orbits can exist at
sufficiently large distances where there will be no stringy effects. The orbits
are dependent upon the energy density, angular momentum and electric field. The
analysis breaks down at radial distances comparable with the compactification
radius and we must resort to using a modified form of the harmonic function in
this region.Comment: Latex, 20 pages, 6 figs, references adde
Discovery and Measurement of Sleptons, Binos, and Winos with a Z'
Extensions of the MSSM could significantly alter its phenomenology at the
LHC. We study the case in which the MSSM is extended by an additional U(1)
gauge symmetry, which is spontaneously broken at a few TeV. The production
cross-section of sleptons is enhanced over that of the MSSM by the process
, so the discovery potential for
sleptons is greatly increased. The flavor and charge information in the
resulting decay, , provides a useful handle on
the identity of the LSP. With the help of the additional kinematical constraint
of an on-shell Z', we implement a novel method to measure all of the
superpartner masses involved in this channel. For certain final states with two
invisible particles, one can construct kinematic observables bounded above by
parent particle masses. We demonstrate how output from one such observable,
m_T2, can become input to a second, increasing the number of measurements one
can make with a single decay chain. The method presented here represents a new
class of observables which could have a much wider range of applicability.Comment: 20 pages, 15 figures; v2 references added and minor change
Exploring the cytotoxicity, uptake, cellular response, and proteomics of mono- and dinuclear DNA light-switch complexes
Drug resistance to platinum chemotherapeutics targeting DNA often involves abrogation of apoptosis, and has emerged as a significant challenge in modern, non-targeted chemotherapy. Consequently, there is great interest in the anti-cancer properties of metal complexes - particularly those that interact with DNA - and mechanisms of consequent cell death. Herein we compare a parent cytotoxic complex [Ru(phen)2(tpphz)]2+ [phen = 1,10-phenanthroline, tpphz = tetrapyridyl [3,2-a:2',3'-c:3'',2''-h:2''',3'''-j] phenazine], with a mononuclear analogue with modified intercalating ligand, [Ru(phen)2(taptp)]2+,[taptp = 4,5,9,18-tetraazaphenanthreno[9,10-b] triphenylene], and two structurally related di-nuclear, tpphz-bridged, heterometallic complexes, RuRe and RuPt. These changes result in a switch from intercalation to groove binding DNA interaction, concomitant reduction in cytotoxic potency, but no significant change in relative cytotoxicity toward platinum-resistant A2780CIS cancer cells, indicating that DNA interaction mode is not critical for the mechanism of platinum resistance. All variants exhibited a light-switch effect, which for the first time, was exploited to investigate timing of cell death by live cell microscopy. Surprisingly, cell death occurred rapidly as a consequence of oncosis, characterized by loss of cytoplasmic volume control, absence of significant mitochondrial membrane potential loss, and lack of activation of apoptotic cell death markers. Importantly, a novel, quantitative proteomic analysis of the A2780 cell genome following exposure to either mononuclear complex reveals changes in protein expression associated with global cell responses to oxidative stress, and DNA replication/repair cellular pathways. This combination of a multiple targeting modality and induction of a non-apoptotic death mechanism makes these complexes highly promising chemotherapeutic cytotoxicity leads
What do young athletes implicitly understand about psychological skills?
One reason sport psychologists teach psychological skills is to enhance performance in sport; but the value of psychological skills for young athletes is questionable because of the qualitative and quantitative differences between children and adults in their understanding of abstract concepts such as mental skills. To teach these skills effectively to young athletes, sport psychologists need to appreciate what young athletes implicitly understand about such skills because maturational (e.g., cognitive, social) and environmental (e.g., coaches) factors can influence the progressive development of children and youth. In the present qualitative study, we explored young athletes’ (aged 10–15 years) understanding of four basic psychological skills: goal setting, mental imagery, self-talk, and relaxation. Young athletes (n = 118: 75 males and 43 females) completed an open-ended questionnaire to report their understanding of these four basic psychological skills. Compared with the older youth athletes, the younger youth athletes were less able to explain the meaning of each psychological skill. Goal setting and mental imagery were better understood than self-talk and relaxation. Based on these findings, sport psychologists should consider adapting interventions and psychoeducational programs to match young athletes’ age and developmental level
D-Brane Dynamics and NS5 Rings
We consider the classical motion of a probe D-brane moving in the background
geometry of a ring of NS5 branes, assuming that the latter are non-dynamical.
We analyse the solutions to the Dirac-Born-Infield (DBI) action governing the
approximate dynamics of the system. In the near horizon (throat) approximation
we find several exact solutions for the probe brane motion. These are compared
to numerical solutions obtained in more general cases. One solution of
particular interest is when the probe undergoes oscillatory motion through the
centre of the ring (and perpendicular to it). By taking the ring radius
sufficiently large, this solution should remain stable to any stringy
corrections coming from open-strings stretching between the probe and the
NS5-branes along the ring.Comment: 17 pages, Latex, 8 figures; References adde
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