2,704 research outputs found
Exploring General Gauge Mediation
We explore various aspects of General Gauge Mediation(GGM). We present a
reformulation of the correlation functions used in GGM, and further elucidate
their IR and UV properties. Additionally we clarify the issue of UV sensitivity
in the calculation of the soft masses in the MSSM, highlighting the role of the
supertrace over the messenger spectrum. Finally, we present weakly coupled
messenger models which fully cover the parameter space of GGM. These examples
demonstrate that the full parameter space of GGM is physical and realizable.
Thus it should be considered a valid basis for future phenomenological
explorations of gauge mediation.Comment: 27 pages, minor changes, typos fixed in appendix
DEVELOPMENT OF A SCADA SYSTEM FOR ACCESS, PROCESSING AND SUPERVISION OF DATA COMING FROM A WIRELESS SENSORS NETWORK IN AGRO-ENVIRONMENTAL APPLICATIONS
Wireless sensors networks appeared in the 1970’s for military and
industrial use. They have since undergone a major evolution, particularly since the 90’s,
thanks to the improvements in wireless communications. These changes have allowed
them to participate in a wide variety of applications in different sectors such as
agriculture and environment. This paper shows the development of a SCADA application
programmed with LabVIEW® 8.6 (National Instruments), which allows management of
data received by wireless sensors networks through a friendly interface for users. For the
application shown in this paper we have worked with a MEP 510 sensors network
(Crossbow). The functionalities implemented are the following: Network configuration;
Data storage into database; Statistical processing of historical data with polynomial
adjustment and spline interpolation; Visualization by data graphics in real time and
historical data; Visualization of 2D intensity diagrams from the spatial distribution of
sensors; and Creation of a users registry system that allows, depending on the category
assigned, receiving or not access privileges in the application. As a complement we have
developed the possibility of remote access. Sensors network implemented and the
applications developed have been checked by operational tests for each functionality, as
well as sensors joining and leaving the network situations, range of variables and working
modes. The results obtained show the robustness of the SCADA application and the
limitations of wireless sensors networks operating on field conditions
Double percolation effects and fractal behavior in magnetic/superconducting hybrids
Perpendicular magnetic anisotropy ferromagnetic/superconducting (FM/SC) bilayers with a labyrinth domain structure are used to study nucleation of superconductivity on a fractal network, tunable through magnetic history. As clusters of reversed domains appear in the FM layer, the SC film shows a percolative behavior that depends on two independent processes: the arrangement of initial reversed domains and the fractal geometry of expanding clusters. For a full labyrinth structure, the behavior of the upper critical field is typical of confined superconductivity on a fractal network
Continuous-distribution puddle model for conduction in trilayer graphene
An insulator-to-metal transition is observed in trilayer graphene based on
the temperature dependence of the resistance under different applied gate
voltages. At small gate voltages the resistance decreases with increasing
temperature due to the increase in carrier concentration resulting from thermal
excitation of electron-hole pairs. At large gate voltages excitation of
electron-hole pairs is suppressed, and the resistance increases with increasing
temperature because of the enhanced electron-phonon scattering. We find that
the simple model with overlapping conduction and valence bands, each with
quadratic dispersion relations, is unsatisfactory. Instead, we conclude that
impurities in the substrate that create local puddles of higher electron or
hole densities are responsible for the residual conductivity at low
temperatures. The best fit is obtained using a continuous distribution of
puddles. From the fit the average of the electron and hole effective masses can
be determined.Comment: 18 pages, 5 figure
Genetic susceptibility loci for cardiovascular disease and their impact on atherosclerotic plaques
Background:
Atherosclerosis is a chronic inflammatory disease in part caused by lipid uptake in the vascular wall, but the exact underlying mechanisms leading to acute myocardial infarction and stroke remain poorly understood. Large consortia identified genetic susceptibility loci that associate with large artery ischemic stroke and coronary artery disease. However, deciphering their underlying mechanisms are challenging. Histological studies identified destabilizing characteristics in human atherosclerotic plaques that associate with clinical outcome. To what extent established susceptibility loci for large artery ischemic stroke and coronary artery disease relate to plaque characteristics is thus far unknown but may point to novel mechanisms.
Methods:
We studied the associations of 61 established cardiovascular risk loci with 7 histological plaque characteristics assessed in 1443 carotid plaque specimens from the Athero-Express Biobank Study. We also assessed if the genotyped cardiovascular risk loci impact the tissue-specific gene expression in 2 independent biobanks, Biobank of Karolinska Endarterectomy and Stockholm Atherosclerosis Gene Expression.
Results:
A total of 21 established risk variants (out of 61) nominally associated to a plaque characteristic. One variant (rs12539895, risk allele A) at 7q22 associated to a reduction of intraplaque fat, P=5.09×10−6 after correction for multiple testing. We further characterized this 7q22 Locus and show tissue-specific effects of rs12539895 on HBP1 expression in plaques and COG5 expression in whole blood and provide data from public resources showing an association with decreased LDL (low-density lipoprotein) and increase HDL (high-density lipoprotein) in the blood.
Conclusions:
Our study supports the view that cardiovascular susceptibility loci may exert their effect by influencing the atherosclerotic plaque characteristics
Thermal shape fluctuation effects in the description of hot nuclei
The behavior of several nuclear properties with temperature is analyzed
within the framework of the Finite Temperature Hartree-Fock-Bogoliubov (FTHFB)
theory with the Gogny force and large configuration spaces. Thermal shape
fluctuations in the quadrupole degree of freedom, around the mean field
solution, are taken into account with the Landau prescription. As
representative examples the nuclei Er, Dy and Hg are
studied. Numerical results for the superfluid to normal and deformed to
spherical shape transitions are presented. We found a substantial effect of the
fluctuations on the average value of several observables. In particular, we get
a decrease in the critical temperature () for the shape transition as
compared with the plain FTHFB prediction as well as a washing out of the shape
transition signatures. The new values of are closer to the ones found in
Strutinsky calculations and with the Pairing Plus Quadrupole model Hamiltonian.Comment: 17 pages, 8 Figure
Naturalness and Higgs Decays in the MSSM with a Singlet
The simplest extension of the supersymmetric standard model - the addition of
one singlet superfield - can have a profound impact on the Higgs and its
decays. We perform a general operator analysis of this scenario, focusing on
the phenomenologically distinct scenarios that can arise, and not restricting
the scope to the narrow framework of the NMSSM. We reexamine decays to four b
quarks and four tau's, finding that they are still generally viable, but at the
edge of LEP limits. We find a broad set of Higgs decay modes, some new,
including those with four gluon final states, as well as more general six and
eight parton final states. We find the phenomenology of these scenarios is
dramatically impacted by operators typically ignored, specifically those
arising from D-terms in the hidden sector, and those arising from weak-scale
colored fields. In addition to sensitivity of m_Z, there are potential tunings
of other aspects of the spectrum. In spite of this, these models can be very
natural, with light stops and a Higgs as light as 82 GeV. These scenarios
motivate further analyses of LEP data as well as studies of the detection
capabilities of future colliders to the new decay channels presented.Comment: 3 figures, 1 appendix; version to appear in JHEP; typos fixed and
additional references and acknowledgements adde
The STAR Silicon Strip Detector (SSD)
The STAR Silicon Strip Detector (SSD) completes the three layers of the
Silicon Vertex Tracker (SVT) to make an inner tracking system located inside
the Time Projection Chamber (TPC). This additional fourth layer provides two
dimensional hit position and energy loss measurements for charged particles,
improving the extrapolation of TPC tracks through SVT hits. To match the high
multiplicity of central Au+Au collisions at RHIC the double sided silicon strip
technology was chosen which makes the SSD a half million channels detector.
Dedicated electronics have been designed for both readout and control. Also a
novel technique of bonding, the Tape Automated Bonding (TAB), was used to
fullfill the large number of bounds to be done. All aspects of the SSD are
shortly described here and test performances of produced detection modules as
well as simulated results on hit reconstruction are given.Comment: 11 pages, 8 figures, 1 tabl
Indirect Dark Matter Detection from Dwarf Satellites: Joint Expectations from Astrophysics and Supersymmetry
We present a general methodology for determining the gamma-ray flux from
annihilation of dark matter particles in Milky Way satellite galaxies, focusing
on two promising satellites as examples: Segue 1 and Draco. We use the
SuperBayeS code to explore the best-fitting regions of the Constrained Minimal
Supersymmetric Standard Model (CMSSM) parameter space, and an independent MCMC
analysis of the dark matter halo properties of the satellites using published
radial velocities. We present a formalism for determining the boost from halo
substructure in these galaxies and show that its value depends strongly on the
extrapolation of the concentration-mass (c(M)) relation for CDM subhalos down
to the minimum possible mass. We show that the preferred region for this
minimum halo mass within the CMSSM with neutralino dark matter is ~10^-9-10^-6
solar masses. For the boost model where the observed power-law c(M) relation is
extrapolated down to the minimum halo mass we find average boosts of about 20,
while the Bullock et al (2001) c(M) model results in boosts of order unity. We
estimate that for the power-law c(M) boost model and photon energies greater
than a GeV, the Fermi space-telescope has about 20% chance of detecting a dark
matter annihilation signal from Draco with signal-to-noise greater than 3 after
about 5 years of observation
Triggering an eruptive flare by emerging flux in a solar active-region complex
A flare and fast coronal mass ejection originated between solar active
regions NOAA 11514 and 11515 on July 1, 2012 in response to flux emergence in
front of the leading sunspot of the trailing region 11515. Analyzing the
evolution of the photospheric magnetic flux and the coronal structure, we find
that the flux emergence triggered the eruption by interaction with overlying
flux in a non-standard way. The new flux neither had the opposite orientation
nor a location near the polarity inversion line, which are favorable for strong
reconnection with the arcade flux under which it emerged. Moreover, its flux
content remained significantly smaller than that of the arcade (approximately
40 %). However, a loop system rooted in the trailing active region ran in part
under the arcade between the active regions, passing over the site of flux
emergence. The reconnection with the emerging flux, leading to a series of jet
emissions into the loop system, caused a strong but confined rise of the loop
system. This lifted the arcade between the two active regions, weakening its
downward tension force and thus destabilizing the considerably sheared flux
under the arcade. The complex event was also associated with supporting
precursor activity in an enhanced network near the active regions, acting on
the large-scale overlying flux, and with two simultaneous confined flares
within the active regions.Comment: Accepted for publication in Topical Issue of Solar Physics: Solar and
Stellar Flares. 25 pages, 12 figure
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