Commissioning of the ATLAS Liquid Argon Calorimeters

A selection of ATLAS liquid argon (LAr) calorimeter commissioning studies is presented. It includes a coherent noise study, a measurement of the quality of the ionization pulse shape prediction, and energy and time reconstruction analyses with cosmic and single beam signals.Comment: Proceedings from the CIPANP 2009 Conferenc

Dark Matter in B-L Extended MSSM Models

We analyze the dark matter problem in the context of supersymmetric U(1)_{B-L} model. In this model, the lightest neutalino can be the B-L gaugino widetilde {Z}_{B-L} or the extra Higgsinos widetilde{chi}_{1,2} dominated. We compute the thermal relic abundance of these particles and show that, unlike the LSP in MSSM, they can account for the observed relic abundance with no conflict with other phenomenological constraints. The prospects for their direct detection, if they are part of our galactic halo, are also discussed.Comment: 11 pages, 9 figures. Published versio

Electroweak Symmetry Breaking and Proton Decay in SO(10) SUSY-GUT with TeV W_R

In a recent paper, we proposed a new class of supersymmetric SO(10) models for neutrino masses where the TeV scale electroweak symmetry is SU(2)_L\times SU(2)_R\times U(1)_{B-L} making the associated gauge bosons W_R and Z' accessible at the Large Hadron Collider. We showed that there exists a domain of Yukawa coupling parameters and symmetry breaking patterns which give an excellent fit to all fermion masses including neutrinos. In this sequel, we discuss an alternative Yukawa pattern which also gives good fermion mass fit and then study the predictions of both models for proton lifetime. Consistency with current experimental lower limits on proton life time require the squark masses of first two generations to be larger than ~ 1.2 TeV. We also discuss how one can have simultaneous breaking of both SU(2)_R\times U(1)_{B-L} and standard electroweak symmetries via radiative corrections.Comment: 31 pages, 5 figures, 4 tables

Charm meson resonances in D→PℓνD \to P \ell \nu decays

Motivated by recent experimental results we reconsider semileptonic $D \to P \ell \nu_{\ell}$ decays within a model which combines heavy quark symmetry and properties of the chiral Lagrangian. We include excited charm meson states, some of them recently observed, in our Lagrangian and determine their impact on the charm meson semileptonic form factors. We find that the inclusion of excited charm meson states in the model leads to a rather good agreement with the experimental results on the $q^2$ shape of the $F_+(q^2)$ form factor. We also calculate branching ratios for all $D \to P \ell \nu_{\ell}$ decays.Comment: 9 pages, 4 figures; minor corrections, added some discussion, version as publishe

Immunocytochemical localization of casein kinase II during interphase and mitosis

We have developed specific antibodies to synthetic peptide antigens that react with the individual subunits of casein kinase II (CKII). Using these antibodies, we studied the localization of CKII in asynchronous HeLa cells by immunofluorescence and immunoelectron microscopy. Further studies were done on HeLa cells arrested at the G1/S transition by hydroxyurea treatment. Our results indicate that the CKII alpha and beta subunits are localized in the cytoplasm during interphase and are distributed throughout the cell during mitosis. Further electron microscopic investigation revealed that CKII alpha subunit is associated with spindle fibers during metaphase and anaphase. In contrast, the CKII alpha' subunit is localized in the nucleus during G1 and in the cytoplasm during S. Taken together, our results suggest that CKII may play significant roles in cell division control by shifting its localization between the cytoplasm and nucleus

Impacts of the Mount Pinatubo eruption on ENSO in the GEOS seasonal-to-subseasonal forecasting system

The eruption of Mount Pinatubo in June 1991 introduced a perturbation of the Earth's global energy budget by increasing the stratospheric aerosol loading by an order of magnitude, with effects on the global climate. In this presentation we analyze the effects of the Mt. Pinatubo eruption on the seasonal forecast performed with Goddard Earth Observing System Seasonal-to Subseasonal (GEOS-S2S) system, an Earth System Model that includes an interactive ocean and a bulk aerosol model coupled to radiation. We performed 10-member ensembles for the year after the eruption (June 1991-May 1992) at ~0.5 horizontal resolution, with and without the inclusion of the Mt. Pinatubo eruption. In GEOS-S2S, the eruption leads to ta strengthening of El Nino peaking in January 1992. The strengthening is mainly due to the weakening of the trade winds, which is caused by a attening of the temperature gradient across the Pacic due to a differential response to the volcanic forcing between the central and eastern Pacic (ocean-dynamical thermostat). This response largely depends on the assumed size for the volcanic aerosols. Indeed, we performed simulations assuming a volcanic aerosol effective radius of 0.35 m (similar to tropospheric aerosol, and the default in GEOS) and 0.6 m (closer to observations of volcanic aerosol from Pinatubo-sized eruptions). We nd that in the latter case the tropical radiative forcing is lower, since smaller aerosols scatter shortwave radiation more eciently than larger ones. Accordingly, the impact on ENSO is not statistically signicant when a larger and more realistic particle radius is assumed

Immunocytochemical localization of the neuron-specific form of the c-src gene product, pp60c-src(+), in rat brain

Neurons express high levels of a variant form of the c-src gene product, denoted pp60c-src(+), which contains a 6 amino acid insert in the amino-terminal half of the c-src protein. We have determined the localization of pp60c-src(+) in neurons using an affinity-purified anti-peptide antibody, referred to as affi-SB12, that exclusively recognizes this neuron-specific form of the c-src gene product. Using affi-SB12, we examined the distribution of pp60c-src(+) by immunoperoxidase staining of sections through adult rat brains, pp60c-src(+) was widely distributed in rat brain and appeared to be differentially expressed in subpopulations of neurons. The majority of immunoreactive neurons was found in the mesencephalon, cerebellum, pons, and medulla. Telencephalic structures that contained substantial populations of pp60c-src(+)-immunoreactive neurons included layer V of the cerebral cortex and the ventral pallidum. Within individual neurons, pp60c-src(+) immunoreactivity was localized to the cell soma and dendritic processes, while labeling of axons and nerve terminals (puncta) was not as readily detected. Dense accumulations of immunoreactive axons were rare, being most prominent in portions of the inferior and superior olive, and in the spinal trigeminal nucleus. While the regional distribution of pp60c-src(+) immunoreactivity does not correlate with any specific neuronal cell type or first messenger system, this unique pattern of expression of pp60c-src(+) suggests the existence of a previously uncharacterized functional organization within the brain. Furthermore, the localization of this neuron-specific tyrosine kinase in functionally important areas of the nerve cell, namely, dendritic processes, axons, and nerve terminals, suggests that pp60c-src(+) may regulate pleiotropic functions in specific classes of neurons in the adult central nervous system

Cloud Optical Depth Retrievals from Solar Background "signal" of Micropulse Lidars

Pulsed lidars are commonly used to retrieve vertical distributions of cloud and aerosol layers. It is widely believed that lidar cloud retrievals (other than cloud base altitude) are limited to optically thin clouds. Here we demonstrate that lidars can retrieve optical depths of thick clouds using solar background light as a signal, rather than (as now) merely a noise to be subtracted. Validations against other instruments show that retrieved cloud optical depths agree within 10-15% for overcast stratus and broken clouds. In fact, for broken cloud situations one can retrieve not only the aerosol properties in clear-sky periods using lidar signals, but also the optical depth of thick clouds in cloudy periods using solar background signals. This indicates that, in general, it may be possible to retrieve both aerosol and cloud properties using a single lidar. Thus, lidar observations have great untapped potential to study interactions between clouds and aerosols

Double Type-II Seesaw, Baryon Asymmetry and Dark Matter for Cosmic e^\pm Excesses

We construct a new realization of type-II seesaw for neutrino masses and baryon asymmetry by extending the standard model with one light and two heavy singlet scalars besides one Higgs triplet. The heavy singlets pick up small vacuum expectation values to give a suppressed trilinear coupling between the triplet and doublet Higgs bosons after the light singlet drives the spontaneous breaking of lepton number. The Higgs triplet can thus remain light and be accessible at the LHC. The lepton number conserving decays of the heavy singlets can generate a lepton asymmetry stored in the Higgs triplet to account for the matter-antimatter asymmetry in the Universe. We further introduce stable gauge bosons from a hidden sector, which obtain masses and annihilate into the Higgs triplet after spontaneous breaking of the associated non-Abelian gauge symmetry. With Breit-Wigner enhancement, the stable gauge bosons can simultaneously explain the relic density of dark matter and the cosmic positron/electron excesses.Comment: 9 pages, 4 figures, minor rewording, final PRD version (in Press

Remote sensing of cloud sides of deep convection: towards a three-dimensional retrieval of cloud particle size profiles

International audienceThe cloud scanner sensor is a central part of a recently proposed satellite remote sensing concept ? the three-dimensional (3-D) cloud and aerosol interaction mission (CLAIM-3D) combining measurements of aerosol characteristics in the vicinity of clouds and profiles of cloud microphysical characteristics. Such a set of collocated measurements will allow new insights in the complex field of cloud-aerosol interactions affecting directly the development of clouds and precipitation, especially in convection. The cloud scanner measures radiance reflected or emitted by cloud sides at several wavelengths to derive a profile of cloud particle size and thermodynamic phase. For the retrieval of effective size a Bayesian approach was adopted and introduced in a preceding paper. In this paper the potential of the approach, which has to account for the complex three-dimensional nature of cloud geometry and radiative transfer, is tested in realistic cloud observing situations. In a fully simulated environment realistic cloud resolving modelling provides complex 3-D structures of ice, water, and mixed phase clouds, from the early stage of convective development to mature deep convection. A three-dimensional Monte Carlo radiative transfer is used to realistically simulate the aspired observations. A large number of cloud data sets and related simulated observations provide the database for an experimental Bayesian retrieval. An independent simulation of an additional cloud field serves as a synthetic test bed for the demonstration of the capabilities of the developed retrieval techniques