58 research outputs found
Technical aspects in dark matter investigations
Some theoretical and experimental aspects regarding the direct dark matter
field are mentioned. In particular some arguments, which play a relevant role
in the evaluation of model dependent interpretations of experimental results
and in comparisons, are shortly addressed.Comment: Proceedings of TAUP 2011 Conferenc
Functional expression of TcoAT1 reveals it to be a P1-type nucleoside transporter with no capacity for diminazene uptake
It has long been established that the Trypanosoma brucei TbAT1/P2 aminopurine transporter is involved in the uptake of diamidine and arsenical drugs including pentamidine, diminazene aceturate and melarsoprol. Accordingly, it was proposed that the closest Trypanosoma congolense paralogue, TcoAT1, might perform the same function in this parasite, and an apparent correlation between a Single Nucleotide Polymorphism (SNP) in that gene and diminazene tolerance was reported for the strains examined. Here, we report the functional cloning and expression of TcoAT1 and show that in fact it is the syntenic homologue of another T. brucei gene of the same Equilibrative Nucleoside Transporter (ENT) family: TbNT10. The T. congolense genome does not seem to contain a syntenic equivalent to TbAT1. Two TcoAT1 alleles, differentiated by three independent SNPs, were expressed in the T. brucei clone B48, a TbAT1-null strain that further lacks the High Affinity Pentamidine Transporter (HAPT1); TbAT1 was also expressed as a control. The TbAT1 and TcoAT1 transporters were functional and increased sensitivity to cytotoxic nucleoside analogues. However, only TbAT1 increased sensitivity to diamidines and to cymelarsan. Uptake of [3H]-diminazene was detectable only in the B48 cells expressing TbAT1 but not TcoAT1, whereas uptake of [3H]-inosine was increased by both TcoAT1 alleles but not by TbAT1. Uptake of [3H]-adenosine was increased by all three ENT genes. We conclude that TcoAT1 is a P1-type purine nucleoside transporter and the syntenic equivalent to the previously characterised TbNT10; it does not mediate diminazene uptake and is therefore unlikely to play a role in diminazene resistance in T. congolense
Species' geographic distributions through time: Playing catchup with changing climates
This is the author's accepted manuscript.Speciesâ ranges are often treated as a rather fixed characteristic, rather than a fluid, ever-changing manifestation of their ecological requirements and dispersal abilities. Paleontologists generally have had a more flexible point of view on this issue than neontologists, but each perspective can improve by appreciating the other. Here, we provide an overview of paleontological and neontological perspectives on speciesâ geographic distributions, focusing on what can be learned about historical variations in distributions. The cross-disciplinary view, we hope, offers some novel perspectives on species-level biogeography
Extended Theories of Gravity
Extended Theories of Gravity can be considered a new paradigm to cure
shortcomings of General Relativity at infrared and ultraviolet scales. They are
an approach that, by preserving the undoubtedly positive results of Einstein's
Theory, is aimed to address conceptual and experimental problems recently
emerged in Astrophysics, Cosmology and High Energy Physics. In particular, the
goal is to encompass, in a self-consistent scheme, problems like Inflation,
Dark Energy, Dark Matter, Large Scale Structure and, first of all, to give at
least an effective description of Quantum Gravity. We review the basic
principles that any gravitational theory has to follow. The geometrical
interpretation is discussed in a broad perspective in order to highlight the
basic assumptions of General Relativity and its possible extensions in the
general framework of gauge theories. Principles of such modifications are
presented, focusing on specific classes of theories like f (R)-gravity and
scalar-tensor gravity in the metric and Palatini approaches. The special role
of torsion is also discussed. The conceptual features of these theories are
fully explored and attention is payed to the issues of dynamical and conformal
equivalence between them considering also the initial value problem. A number
of viability criteria are presented considering the post-Newtonian and the
post-Minkowskian limits. In particular, we discuss the problems of neutrino
oscillations and gravitational waves in Extended Gravity. Finally, future
perspectives of Extended Gravity are considered with possibility to go beyond a
trial and error approach.Comment: 184 pages, 3 figures, survey to appear in Physics Report
Neutrinos
229 pages229 pages229 pagesThe Proceedings of the 2011 workshop on Fundamental Physics at the Intensity Frontier. Science opportunities at the intensity frontier are identified and described in the areas of heavy quarks, charged leptons, neutrinos, proton decay, new light weakly-coupled particles, and nucleons, nuclei, and atoms
Persistent Place-Making in Prehistory: the Creation, Maintenance, and Transformation of an Epipalaeolithic Landscape
Most archaeological projects today integrate, at least to some degree, how past people engaged with their surroundings, including both how they strategized resource use, organized technological production, or scheduled movements within a physical environment, as well as how they constructed cosmologies around or created symbolic connections to places in the landscape. However, there are a multitude of ways in which archaeologists approach the creation, maintenance, and transformation of human-landscape interrelationships. This paper explores some of these approaches for reconstructing the Epipalaeolithic (ca. 23,000â11,500 years BP) landscape of Southwest Asia, using macro- and microscale geoarchaeological approaches to examine how everyday practices leave traces of human-landscape interactions in northern and eastern Jordan. The case studies presented here demonstrate that these Epipalaeolithic groups engaged in complex and far-reaching social landscapes. Examination of the Early and Middle Epipalaeolithic (EP) highlights that the notion of âNeolithizationâ is somewhat misleading as many of the features we use to define this transition were already well-established patterns of behavior by the Neolithic. Instead, these features and practices were enacted within a hunter-gatherer world and worldview
Rapid loss of flight in the Aldabra white-throated rail
Flight loss has evolved independently in numerous island bird lineages worldwide, and particularly in rails (Rallidae). The Aldabra white-throated rail (Dryolimnas [cuvieri] aldabranus) is the last surviving flightless bird in the western Indian Ocean, and the only living flightless subspecies within Dryolimnas cuvieri, which is otherwise volant across its extant range. Such a difference in flight capacity among populations of a single species is unusual, and could be due to rapid evolution of flight loss, or greater evolutionary divergence than can readily be detected by traditional taxonomic approaches. Here we used genetic and morphological analyses to investigate evolutionary trajectories of living and extinct Dryolimnas cuvieri subspecies. Our data places D. [c.] aldabranus among the most rapid documented avian flight loss cases (within an estimated maximum of 80,000â130,000 years). However, the unusual intraspecific variability in flight capacity within D. cuvieri is best explained by levels of genetic divergence, which exceed those documented between other volant taxa versus flightless close relatives, all of which have full species status. Our results also support consideration of Dryolimnas [cuvieri] aldabranus as sufficiently evolutionary distinct from D. c. cuvieri to warrant management as an evolutionary significant unit. Trait variability among closely related lineages should be considered when assessing conservation status, particularly for traits known to influence vulnerability to extinction (e.g. flightlessness)
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