1,743 research outputs found
Probing the messenger of supersymmetry breaking by the muon anomalous magnetic moment
Motivated by the recently measured muon's anomalous magnetic moment
, we examine the supersymmetry contribution to in various
mediation models of supersymmetry breaking which lead to predictive flavor
conserving soft parameters at high energy scale. The studied models include
dilaton/modulus-mediated models in heterotic string/ theory, gauge-mediated
model, no-scale or gaugino-mediated model, and also the minimal and deflected
anomaly-mediated models. For each model, the range of allowed
by other experimental constraints, e.g. b --> s\gamma and the collider bounds
on superparticle masses, is obtained together with the corresponding parameter
region of the model. Gauge-mediated models with low messenger scale can give
any within the bound. In many other models, b -->
s\gamma favors smaller than either the value
() or the central value ().Comment: RevTeX, 29 pages, 14 eps figures, figure for deflected anomaly
mediation is corrected, reference adde
A Logical Model and Data Placement Strategies for MEMS Storage Devices
MEMS storage devices are new non-volatile secondary storages that have
outstanding advantages over magnetic disks. MEMS storage devices, however, are
much different from magnetic disks in the structure and access characteristics.
They have thousands of heads called probe tips and provide the following two
major access facilities: (1) flexibility: freely selecting a set of probe tips
for accessing data, (2) parallelism: simultaneously reading and writing data
with the set of probe tips selected. Due to these characteristics, it is
nontrivial to find data placements that fully utilize the capability of MEMS
storage devices. In this paper, we propose a simple logical model called the
Region-Sector (RS) model that abstracts major characteristics affecting data
retrieval performance, such as flexibility and parallelism, from the physical
MEMS storage model. We also suggest heuristic data placement strategies based
on the RS model and derive new data placements for relational data and
two-dimensional spatial data by using those strategies. Experimental results
show that the proposed data placements improve the data retrieval performance
by up to 4.0 times for relational data and by up to 4.8 times for
two-dimensional spatial data of approximately 320 Mbytes compared with those of
existing data placements. Further, these improvements are expected to be more
marked as the database size grows.Comment: 37 page
Two Higgs doublet models for the LHC Higgs boson data at 7 and 8 TeV
Updated LHC data on the new 126 GeV boson during the 7 and 8 TeV runnings
strengthen the standard model Higgs boson interpretation further. Through the
global analysis, we investigate whether the new particle could be one
of the scalar particles in two Higgs doublet models. Four types (Type I, II, X
and Y) are comprehensively studied. Taking the recent analysis on the
spin-parity of the new boson, we consider two scenarios: the new boson is
either the light CP-even one () or the heavy CP-even one (). It is
found that both scenarios are consistent with the new data, not only in the
parameter regions near the decoupling limit but also in other regions far from
the decoupling limit. In addition, the current data are compatible with the
possibility that the light Higgs boson is hidden in the mass window of
90-100 GeV. The diphoton or channel can provide a probe of this
possibility by the enhanced signal rates.Comment: To appear in JHE
Development of a hybrid magnetic resonance/computed tomography-compatible phantom for magnetic resonance guided radiotherapy
The purpose of the present study was to develop a hybrid magnetic resonance/computed tomography (MR/CT)-compatible phantom and tissue-equivalent materials for each MR and CT image. Therefore, the essential requirements necessary for the development of a hybrid MR/CT-compatible phantom were determined and the development process is described. A total of 12 different tissue-equivalent materials for each MR and CT image were developed from chemical components. The uniformity of each sample was calculated. The developed phantom was designed to use 14 plugs that contained various tissue-equivalent materials. Measurement using the developed phantom was performed using a 3.0-T scanner with 32 channels and a Somatom Sensation 64. The maximum percentage difference of the signal intensity (SI) value on MR images after adding K2CO3 was 3.31%. Additionally, the uniformity of each tissue was evaluated by calculating the percent image uniformity (%PIU) of the MR image, which was 82.18 ±1.87% with 83% acceptance, and the average circular-shaped regions of interest (ROIs) on CT images for all samples were within ±5 Hounsfield units (HU). Also, dosimetric evaluation was performed. The percentage differences of each tissue-equivalent sample for average dose ranged from -0.76 to 0.21%. A hybrid MR/CT-compatible phantom for MR and CT was investigated as the first trial in this field of radiation oncology and medical physics
Translational repression of mouse mu opioid receptor expression via leaky scanning
Mu opioid receptor (MOR) expression is under temporal and spatial controls, but expression levels of the MOR gene are relatively low in vivo. In addition to transcriptional regulations, upstream AUGs (uAUGs) and open reading frames (uORFs) profoundly affect the translation of the primary ORF and thus the protein levels in several genes. The 5′-untranslated region (UTR) of mouse MOR mRNA contains three uORFs preceding the MOR main initiation codon. In MOR-fused EGFP or MOR promoter/luciferase reporter constructs, mutating each uAUG individually or in combinations increased MOR transient heterologous expression in neuroblastoma NMB and HEK293 cells significantly. Translation of such constructs increased up to 3-fold without altering the mRNA levels if either the third uAUG or both the second and third AUGs were mutated. Additionally, these uAUG-mediated translational inhibitions were independent of their peptide as confirmed by internal mutation analyses in each uORF. Translational studies indicated that protein syntheses were initiated at these uAUG initiation sites, with the third uAUG initiating the highest translation level. These results support the hypothesis that uORFs in mouse MOR mRNA act as negative regulators through a ribosome leaky scanning mechanism. Such leaky scanning resulted in the suppression of mouse MOR under normal conditions
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