Noncommutative geometry inspired black holes in higher dimensions at the LHC

When embedding models of noncommutative geometry inspired black holes into the peridium of large extra dimensions, it is natural to relate the noncommutativity scale to the higher-dimensional Planck scale. If the Planck scale is of the order of a TeV, noncommutative geometry inspired black holes could become accessible to experiments. In this paper, we present a detailed phenomenological study of the production and decay of these black holes at the Large Hadron Collider (LHC). Noncommutative inspired black holes are relatively cold and can be well described by the microcanonical ensemble during their entire decay. One of the main consequences of the model is the existence of a black hole remnant. The mass of the black hole remnant increases with decreasing mass scale associated with noncommutative and decreasing number of dimensions. The experimental signatures could be quite different from previous studies of black holes and remnants at the LHC since the mass of the remnant could be well above the Planck scale. Although the black hole remnant can be very heavy, and perhaps even charged, it could result in very little activity in the central detectors of the LHC experiments, when compared to the usual anticipated black hole signatures. If this type of noncommutative inspired black hole can be produced and detected, it would result in an additional mass threshold above the Planck scale at which new physics occurs.Comment: 21 pages, 7 figure

Constraints on Pluto’s H and CH₄ profiles from New Horizons Alice Lyα observations

The Alice spectrograph on New Horizons performed several far-ultraviolet (FUV) airglow observations during the July 2015 flyby of Pluto. One of these observations, named PColor2, was a short (226 s) scan across the dayside disk of Pluto from a range of ∼34,000 km, at about 40 minutes prior to closest approach. The brightest observed FUV airglow signal at Pluto is the Lyman alpha (Lyα) emission line of atomic hydrogen, which arises primarily through the resonant scattering of solar Lyα by H atoms in the upper atmosphere, with a brightness of about 30 Rayleighs. Pluto appears dark against the much brighter (∼100 Rayleigh) sky background; this sky background is likewise the result of resonantly scattered solar Lyα, in this case by H atoms in the interplanetary medium (IPM). Here we use an updated photochemical model and a resonance line radiative transfer model to perform detailed simulations of the Lyα emissions observed in the Alice PColor2 scan. The photochemical models show that H and CH₄ abundances in Pluto’s upper atmosphere are a very strong function of the near-surface mixing ratio of CH₄, and could provide a useful way to remotely monitor seasonal climate variations in Pluto’s lower atmosphere. The morphology of the PColor2 Lyα emissions provides constraints on the current abundance profiles of H atoms and CH₄ molecules in Pluto’s atmosphere, and indicate that the globally averaged near-surface mixing ratio of CH₄ is currently close to 0.4%. This new result thus provides independent confirmation of one of the primary results from the solar occultation, also observed with the New Horizons Alice ultraviolet spectrograph

Constraints on Pluto’s H and CH₄ profiles from New Horizons Alice Lyα observations

The Alice spectrograph on New Horizons performed several far-ultraviolet (FUV) airglow observations during the July 2015 flyby of Pluto. One of these observations, named PColor2, was a short (226 s) scan across the dayside disk of Pluto from a range of ∼34,000 km, at about 40 minutes prior to closest approach. The brightest observed FUV airglow signal at Pluto is the Lyman alpha (Lyα) emission line of atomic hydrogen, which arises primarily through the resonant scattering of solar Lyα by H atoms in the upper atmosphere, with a brightness of about 30 Rayleighs. Pluto appears dark against the much brighter (∼100 Rayleigh) sky background; this sky background is likewise the result of resonantly scattered solar Lyα, in this case by H atoms in the interplanetary medium (IPM). Here we use an updated photochemical model and a resonance line radiative transfer model to perform detailed simulations of the Lyα emissions observed in the Alice PColor2 scan. The photochemical models show that H and CH₄ abundances in Pluto’s upper atmosphere are a very strong function of the near-surface mixing ratio of CH₄, and could provide a useful way to remotely monitor seasonal climate variations in Pluto’s lower atmosphere. The morphology of the PColor2 Lyα emissions provides constraints on the current abundance profiles of H atoms and CH₄ molecules in Pluto’s atmosphere, and indicate that the globally averaged near-surface mixing ratio of CH₄ is currently close to 0.4%. This new result thus provides independent confirmation of one of the primary results from the solar occultation, also observed with the New Horizons Alice ultraviolet spectrograph

Laetoli Footprints Preserve Earliest Direct Evidence of Human-Like Bipedal Biomechanics

Background Debates over the evolution of hominin bipedalism, a defining human characteristic, revolve around whether early bipeds walked more like humans, with energetically efficient extended hind limbs, or more like apes with flexed hind limbs. The 3.6 million year old hominin footprints at Laetoli, Tanzania represent the earliest direct evidence of hominin bipedalism. Determining the kinematics of Laetoli hominins will allow us to understand whether selection acted to decrease energy costs of bipedalism by 3.6 Ma. Methodology/Principal Findings Using an experimental design, we show that the Laetoli hominins walked with weight transfer most similar to the economical extended limb bipedalism of humans. Humans walked through a sand trackway using both extended limb bipedalism, and more flexed limb bipedalism. Footprint morphology from extended limb trials matches weight distribution patterns found in the Laetoli footprints. Conclusions These results provide us with the earliest direct evidence of kinematically human-like bipedalism currently known, and show that extended limb bipedalism evolved long before the appearance of the genus Homo. Since extended-limb bipedalism is more energetically economical than ape-like bipedalism, energy expenditure was likely an important selection pressure on hominin bipeds by 3.6 Ma

Future changes in tropical cyclone activity in the North Indian Ocean projected by high-resolution MRI-AGCMs

Open Access at publisher's web site: http://www.springerlink.com/content/b682734237171631

Genetics, recombination and clinical features of human rhinovirus species C (HRV-C) infections; interactions of HRV-C with other respiratory viruses

To estimate the frequency, molecular epidemiological and clinical associations of infection with the newly described species C variants of human rhinoviruses (HRV), 3243 diagnostic respiratory samples referred for diagnostic testing in Edinburgh were screened using a VP4-encoding region-based selective polymerase chain reaction (PCR) for HRV-C along with parallel PCR testing for 13 other respiratory viruses. HRV-C was the third most frequently detected behind respiratory syncytial virus (RSV) and adenovirus, with 141 infection episodes detected among 1885 subjects over 13 months (7.5%). Infections predominantly targeted the very young (median age 6–12 months; 80% of infections in those <2 years), occurred throughout the year but with peak incidence in early winter months. HRV-C was detected significantly more frequently among subjects with lower (LRT) and upper respiratory tract (URT) disease than controls without respiratory symptoms; HRV-C mono-infections were the second most frequently detected virus (behind RSV) in both disease presentations (6.9% and 7.8% of all cases respectively). HRV variants were classified by VP4/VP2 sequencing into 39 genotypically defined types, increasing the current total worldwide to 60. Through sequence comparisons of the 5′untranslated region (5′UTR), the majority grouped with species A (n = 96; 68%, described as HRV-Ca), the remainder forming a phylogenetically distinct 5′UTR group (HRV-Cc). Multiple and bidirectional recombination events between HRV-Ca and HRV-Cc variants and with HRV species A represents the most parsimonious explanation for their interspersed phylogeny relationships in the VP4/VP2-encoding region. No difference in age distribution, seasonality or disease associations was identified between HRV-Ca and HRV-Cc variants. HRV-C-infected subjects showed markedly reduced detection frequencies of RSV and other respiratory viruses, providing evidence for a major interfering effect of HRV-C on susceptibility to other respiratory virus infections. HRV-C's disease associations, its prevalence and evidence for interfering effects on other respiratory viruses mandates incorporation of rhinoviruses into future diagnostic virology screening

Gravitino dark matter in the constrained next-to-minimal supersymmetric standard model with neutralino next-to-lightest superpartner

The viability of a possible cosmological scenario is investigated. The theoretical framework is the constrained next-to-minimal supersymmetric standard model (cNMSSM), with a gravitino playing the role of the lightest supersymmetric particle (LSP) and a neutralino acting as the next-to-lightest supersymmetric particle (NLSP). All the necessary constraints from colliders and cosmology have been taken into account. For gravitino we have considered the two usual production mechanisms, namely out-of equillibrium decay from the NLSP, and scattering processes from the thermal bath. The maximum allowed reheating temperature after inflation, as well as the maximum allowed gravitino mass are determined.Comment: 20 pages, 5 figure

The porin and the permeating antibiotic: A selective diffusion barrier in gram-negative bacteria

Gram-negative bacteria are responsible for a large proportion of antibiotic resistant bacterial diseases. These bacteria have a complex cell envelope that comprises an outer membrane and an inner membrane that delimit the periplasm. The outer membrane contains various protein channels, called porins, which are involved in the influx of various compounds, including several classes of antibiotics. Bacterial adaptation to reduce influx through porins is an increasing problem worldwide that contributes, together with efflux systems, to the emergence and dissemination of antibiotic resistance. An exciting challenge is to decipher the genetic and molecular basis of membrane impermeability as a bacterial resistance mechanism. This Review outlines the bacterial response towards antibiotic stress on altered membrane permeability and discusses recent advances in molecular approaches that are improving our knowledge of the physico-chemical parameters that govern the translocation of antibiotics through porin channel