6,854 research outputs found
Mass matrix Ansatz and lepton flavor violation in the THDM-III
Predictive Higgs-fermion couplings can be obtained when a specific texture
for the fermion mass matrices is included in the general two-Higgs doublet
model. We derive the form of these couplings in the charged lepton sector using
a Hermitian mass matrix Ansatz with four-texture zeros. The presence of
unconstrained phases in the vertices phi-li-lj modifies the pattern of
flavor-violating Higgs interactions. Bounds on the model parameters are
obtained from present limits on rare lepton flavor violating processes, which
could be extended further by the search for the decay tau -> mu mu mu and mu-e
conversion at future experiments. The signal from Higgs boson decays phi -> tau
mu could be searched at the large hadron collider (LHC), while e-mu transitions
could produce a detectable signal at a future e mu-collider, through the
reaction e mu -> h0 -> tau tau.Comment: 17 pages, 9 figure
Synthesis of MgB4O7:Dy3+and Thermoluminescent Characteristics at Low Doses of Beta Radiation
The synthesis and thermoluminescent characteristics of dysprosium-doped MgB4O7 are analyzed. The phosphor at different concentrations (0, 0.1, 0.5, 1, 2 and 4 mol%) of the dopant was prepared by the solution-assisted method. The magnesium borate compound was confirmed by X-ray diffraction. The annealing and dopant concentrations effects on the crystalline matrix were investigated. The highest thermoluminescent sensitivity was found with 450°C of annealing temperature and at high Dy3+ concentration too. The un-doped MgB4O7 phosphor shows a broad glow curve which peaked at 199°C and about 306 °C. Introducing Dy3+ dopant in the matrix that behavior was strongly changed. The wide glow curve shows three glow peaks; two small shoulders at 124 and 195 °C, and a highest peak between 323 and 336 °C temperature range. A large linear dose-response (5 – 2000 mGy) beta dose was obtained. The complex glow curves were deconvolved and the kinetics parameters were determined considering the general order kinetics model
Minimal supersymmetric standard model with gauge mediated supersymmetry breaking and neutrinoless double beta decay
The Minimal Supersymmetric Standard Model with gauge mediated supersymmetry
breaking and trilinear R-parity violation is applied to the description of
neutrinoless double beta decay. A detailed study of limits on the parameter
space coming from the B to (X,gamma) processes by using the recent CLEO results
is performed. The importance of two-nucleon and pion-exchange realizations of
neutrinoless double beta decay together with gluino and neutralino
contributions to this process are addressed. We have deduced new limits on the
trilinear R-parity breaking parameter lambda_{111}' from the non-observability
of 0 nu beta beta in several medium and heavy open-shell nuclei for different
gauge mediated breaking scenarios. In general, they are stronger than those
known from other analyses. Also some studies with respect to the future
neutrinoless double beta decay projects are presented.Comment: 10 pages, 7 figure
Performance evaluation of surgical techniques for treatment of scapholunate instability in a type II wrist
Bounds for Lepton Flavor Violation and the Pseudoscalar Higgs in the General Two Higgs Doublet Model using muon factor
Current experimental data from the muon factor, seems to show the
necessity of physics beyond the Standard Model (SM), since the difference
between SM and experimental predictions is 2.6. In the framework of
the General Two Higgs Doublet Model (2HDM), we calculate the muon anomalous
magnetic moment to get lower and upper bounds for the Flavour Changing (FC)
Yukawa couplings in the leptonic sector. We also obtain lower bounds for the
mass of the pseudoscalar Higgs () as a function of the parameters of
the model.Comment: 12 pages, RevTex4, 5 figures. Improved presentation, updated
experimental data, amplified analysis, new figures added. Subbmited to Phys.
Rev.
Aromatase and COX in Breast Cancer: Enzyme Inhibitors and Beyond
Aromatase expression and enzyme activity in breast cancer patients is greater in or near the tumor tissue compared with the normal breast tissue. Complex regulation of aromatase expression in human tissues involves alternative promoter sites that provide tissue-specific control. Previous studies in our laboratories suggested a strong association between aromatase (CYP19) gene expression and the expression of cyclooxygenase (COX) genes. Additionally, nonsteroidal anti-inflammatory drugs (NSAIDs) and COX selective inhibitors can suppress CYP19 gene expression and decrease aromatase activity. Our current hypothesis is that pharmacological regulation of aromatase and/or cyclooxygenases can act locally to decrease the biosynthesis of estrogen and may provide additional therapy options for patients with hormone-dependent breast cancer. Two pharmacological approaches are being developed, one involving mRNA silencing by selective short interfering RNAs (siRNA) molecules and the second utilizing small molecule drug design. In the first approach, short interfering RNAs were designed against either human aromatase mRNA or human COX-2 mRNA. Treatment of breast cancer cells with siAROMs completely masked the aromatase enzyme activity. Treatment with COX-2 siRNAs decreased the expression of COX-2 mRNA; furthermore, the siCOX-2-mediated decrease also resulted in suppression of CYP19 mRNA. The small molecule drug design approach focuses on the synthesis and biological evaluation of a novel series of sulfonanilide analogs derived from the COX-2 selective inhibitors. The compounds suppress aromatase enzyme activity in SK-BR-3 breast cancer cells in a dose and time-dependent manner, and structure activity analysis does not find a correlation between aromatase suppression and COX inhibition. Real-time PCR analysis demonstrates that the sulfonanilide analogs decrease aromatase gene transcription in breast cells. Thus, these results suggest that the siRNAs and novel sulfonanilides targeting aromatase expression may be valuable tools for selective regulation of aromatase in breast cancer
New Higgs signals induced by mirror fermion mixing effects
We study the conditions under which flavor violation arises in scalar-fermion
interactions, as a result of the mixing phenomena between the standard model
and exotic fermions. Phenomenological consequences are discussed within the
specific context of a left-right model where these additional fermions have
mirror properties under the new SU(2)_R gauge group.
Bounds on the parameters of the model are obtained from LFV processes; these
results are then used to study the LFV Higgs decays (H --> tau l_j, l_j = e,
mu), which reach branching ratios that could be detected at future colliders.Comment: 12 pages, 2 figures, ReVTex4, graphicx, to be published in Phys. Rev.
Preparation of Dipteran Larvae for Scanning Electron Microscopy with Special Reference to Myiasigen Dipteran Species
Although controversy exists concerning the role of chemical fixatives in scanning electron microscopy (SEM) studies of Dipteran larvae, we have observed that filtered 10% formaldehyde solution gives excellent results as a preservative. After immersing in vivo in formaldehyde, the larvae material is preserved for prolonged periods (up to 8 months), before examination with SEM. As a fixative, formaldehyde preserves the structure of the larval cuticle and produces no visible artifacts. Moreover, postfixation is not necessary.
Due to pecularities of the way of life of Wohlfahrtia magnifica (principally the accumulations of necrotic tissue, purulent particles, and other types of substances that often adhere to the numerous spines of larvae), this species must be cleaned before examination by SEM. Manual cleaning with alternating bidistilled water and 0.9% saline solution proved to be a rapid, easy and inexpensive method that gave good results.
Both lyophilization drying and critical point drying were used before sputtering the material. While lyophilization drying proved to be the most effective method for instars II and III, critical point drying was the best technique for study of specimens belonging to instar I. The optimum time for drying and conditions for lyophilization and sputter-coating with gold were determined experimentally. Samples were mounted on SEM stubs with double-sided adhesive and silver conductive paint.
The method proposed is easy and effective for the SEM study of larvae myiasis-producing diptera
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