51 research outputs found
Transverse momentum dependence of directed particle flow at 160 AGeV
The transverse momentum () dependence of hadron flow at SPS energies is
studied. In particular, the nucleon and pion flow in S+S and Pb+Pb collisions
at 160 AGeV is investigated. For simulations the microscopic quark-gluon string
model (QGSM) is applied. It is found that the directed flow of pions changes sign from a negative slope in the low- region to a
positive slope at GeV/c as recently also observed
experimentally. The change of the flow behaviour can be explained by early
emission times for high- pions. We further found that a substantial amount
of high- pions are produced in the very first primary NN collisions at the
surface region of the touching nuclei. Thus, at SPS energies high-
nucleons seem to be a better probe for the hot and dense early phase of nuclear
collisions than high- pions. Both, in the light and in the heavy system
the pion directed flow exhibits large negative values when
the transverse momentum approaches zero, as also seen experimentally in Pb+Pb
collisions. It is found that this effect is caused by nuclear shadowing. The
proton flow, in contrary, shows the typical linear increase with rising .Comment: REVTEX, 20 pages incl. 6 figures, revised and extended versio
Pair-Hopping Mechanism for Layered Superconductors
We propose a possible charge fluctuation effect expected in layered
superconducting materials. In the multireference density functional theory,
relevant fluctuation channels for the Josephson coupling between
superconducting layers include the interlayer pair hopping derived from the
Coulomb repulsion. When interlayer single-electron tunneling processes are
irrelevant in the Kohn-Sham electronic band structure calculation, the two-body
effective interactions stabilize a superconducting phase. This state is also
regarded as a valence-bond solid in a bulk electronic state. The hidden order
parameters coexist with the superconducting order parameter when the charging
effect of a layer is comparable to the pair hopping. Relevant materials
structures favorable for the pair-hopping mechanism are discussed.Comment: 24 pages, 2 figures, to be published in J. Phys. Soc. Jpn. (2009
Dilepton production in heavy ion collisions at intermediate energies
We present a unified description of the vector meson and dilepton production
in elementary and in heavy ion reactions. The production of vector mesons
() is described via the excitation of nuclear resonances ().
The theoretical framework is an extended vector meson dominance model (eVMD).
The treatment of the resonance decays with arbitrary spin is
covariant and kinematically complete. The eVMD includes thereby excited vector
meson states in the transition form factors. This ensures correct asymptotics
and provides a unified description of photonic and mesonic decays. The
resonance model is successfully applied to the production in
reactions. The same model is applied to the dilepton production in elementary
reactions (). Corresponding data are well reproduced. However, when
the model is applied to heavy ion reactions in the BEVALAC/SIS energy range the
experimental dilepton spectra measured by the DLS Collaboration are
significantly underestimated at small invariant masses. As a possible solution
of this problem the destruction of quantum interference in a dense medium is
discussed. A decoherent emission through vector mesons decays enhances the
corresponding dilepton yield in heavy ion reactions. In the vicinity of the
-peak the reproduction of the data requires further a substantial
collisional broadening of the and in particular of the meson.Comment: 32 pages revtex, 19 figures, to appear in PR
Isospin Physics in Heavy-Ion Collisions at Intermediate Energies
In nuclear collisions induced by stable or radioactive neutron-rich nuclei a
transient state of nuclear matter with an appreciable isospin asymmetry as well
as thermal and compressional excitation can be created. This offers the
possibility to study the properties of nuclear matter in the region between
symmetric nuclear matter and pure neutron matter. In this review, we discuss
recent theoretical studies of the equation of state of isospin-asymmetric
nuclear matter and its relations to the properties of neutron stars and
radioactive nuclei. Chemical and mechanical instabilities as well as the
liquid-gas phase transition in asymmetric nuclear matter are investigated. The
in-medium nucleon-nucleon cross sections at different isospin states are
reviewed as they affect significantly the dynamics of heavy ion collisions
induced by radioactive beams. We then discuss an isospin-dependent transport
model, which includes different mean-field potentials and cross sections for
the proton and neutron, and its application to these reactions. Furthermore, we
review the comparisons between theoretical predictions and available
experimental data. In particular, we discuss the study of nuclear stopping in
terms of isospin equilibration, the dependence of nuclear collective flow and
balance energy on the isospin-dependent nuclear equation of state and cross
sections, the isospin dependence of total nuclear reaction cross sections, and
the role of isospin in preequilibrium nucleon emissions and subthreshold pion
production.Comment: 101 pages with embedded epsf figures, review article for
"International Journal of Modern Physics E: Nuclear Physics". Send request
for a hard copy to 1/author
Curcumin-induced inhibition of cellular reactive oxygen species generation: novel therapeutic implications
There is evidence for increased levels of circulating reactive oxygen species (ROS) in diabetics, as indirectly inferred by the findings of increased lipid peroxidation and decreased antioxidant status. Direct measurements of intracellular generation of ROS using fluorescent dyes also demonstrate an association of oxidative stress with diabetes. Although phenolic compounds attenuate oxidative stress-related tissue damage, there are concerns over toxicity of synthetic phenolic antioxidants and this has considerably stimulated interest in investigating the role of natural phenolics in medicinal applications. Curcumin (the primary active principle in turmeric, Curcuma longa Linn.) has been claimed to represent a potential antioxidant and antiinflammatory agent with phytonutrient and bioprotective properties. However there are lack of molecular studies to demonstrate its cellular action and potential molecular targets. In this study the antioxidant effect of curcumin as a function of changes in cellular ROS generation was tested. Our results clearly demonstrate that curcumin abolished both phorbol-12 myristate-13 acetate (PMA) and thapsigargin-induced ROS generation in cells from control and diabetic subjects. The pattern of these ROS inhibitory effects as a function of dose-dependency suggests that curcumin mechanistically interferes with protein kinase C (PKC) and calcium regulation. Simultaneous measurements of ROS and Ca2+ influx suggest that a rise in cytosolic Ca2+ may be a trigger for increased ROS generation. We suggest that the antioxidant and antiangeogenic actions of curcumin, as a mechanism of inhibition of Ca2+ entry and PKC activity, should be further exploited to develop suitable and novel drugs for the treatment of diabetic retinopathy and other diabetic complications
Maxillary Tumor in the Base of the Skull
A large bony swelling in the region of body of maxilla with extension to nasal, zygomatic and palatal region suspected to be a malignant tumor or aggressive benign tumor is clinically recorded and investigated. Conventional radiograph of skull reveals that a radiopacity in the region of body of maxilla obliterating the maxillary antrum with areas of radiolucency. The radiopacity extends to nasal, zygomatic, palatal and lateral wall of the nose. Computerized Tomography image revealed in both coronal and axial view, a well-defined soft tissue mass with areas of calcifications. The mass extended to the base of the skull towards the lateral part of the sphenoid sinus. The margins are well defined and not infiltrative in nature.
Biopsy revealed that it was a cemento-ossifying fibroma. Thus a swelling clinically appeared as malignant tumor was diagnosed as benign tumor with extension to the base of the skull without any complications. The case is presented and discussed
Knowledge, attitude and perception on OPMD among oral medicine specialists
BACKGROUND: Oral potentially malignant disorders are common oral mucosal lesions associated with tobacco habit mainly and few congenital, immunologically mediated mucocutaneous disorders with increased risk for malignant transformation diseases. Aim: The aim of this questionnaire study is to assess the awareness of evidence based medical management of OPMDs among oral medicine specialists in a university setting. The questionnaire based study was conducted among 100 participants. A self-administered questionnaire was used. Sampling was done by convenient sampling. The study was done in a university setting. The questionnaires were distributed to the post graduates and teaching faculties with varied teaching experience in Oral medicine speciality. It was circulated using an online search software, google form and the response was collected through it. CONCLUSION: The collected data was ranked as good, average and below average and the data collected were stored and results were analysed by SPSS software. Out of 100, the need of educational programs exclusively on topical therapeutics in management of oral mucosal lesions to be initiated from the beginning of post-graduation course and educational programs on current updates of topical therapeutics is essential for Oral Medicine Specialist to ensure proper treatment protocol in dental practice
Tuberculous Granuloma
Tuberculosis is a chronic granulomatous disease caused by Mycobacterium tuberculosis. There are two forms namely primary and secondary tuberculosis. Pulmonary tuberculosis is the most common form of primary tuberculosis. Primary tuberculosis in extrapulmonary site, though very uncommon, can occur in any site such as skin, brain, bone, eye, genitourinary tract and oral cavity.
A 50-year-old male reported with complaint of swelling in the left maxillary region for 3 months duration. Intraorally diffuse firm swelling in the buccal mucosa with mild tenderness, free of secondary changes was present. Histhopathological report revealed Langhans′ giant cell suggestive of tuberculous granuloma. This article emphasis the fact that primary oral tuberculosis should be considered as differential diagnosis of soft tissue swellings, as the communicable nature of the disease demands early diagnosis and treatment
Preparation of oregano, coffee and black cumin aqueous formulation and its anti inflammatory activity
Background: Origanum vulgare (referred to as Spanish thyme and wild marjoram),is a member of the plant family Lamiaceae. Oregano contains potent components which contributes towards the cardiovascular and nervous systems, relieves symptoms of inflammation, and modulates blood sugar and lipids. Coffee which contains polyphenols attributes to a number of pharmacological activities that include antioxidant, antiinflammatory, immunomodulatory, anti-microbial, anti-cancer, cardioprotective and neuroprotective effects. Nigella sativa, black caraway is also called kalonji or nigella, and more common in the Far East, Mideast, Bangladesh, India and Africa. Nigella sativa contains active ingredients, in particular, thymoquinone, the main active constituent known for anti-inflammatory effect. Aim: To evaluate the antiinflammatory effect of oregano, coffee and black cumin formulation. Materials and methods: This study includes the usage of about 1g of oregano, coffee and black cumin extracts mixed with 100 mL of distilled water and boiled for 15 minutes, filtered and again concentrated till 10mL.The antiinflammatory activity of this formulation is assessed by using Bovine Serum Albumin assay. Results: The anti-inflammatory activity of oregano, coffee and black cumin aqueous formulation shows about 65% of inhibition when compared with standard
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