787 research outputs found
Procjena in vitro protoskolicidne učinkovitosti metanolnih biljnih ekstrakata na hidatidne ciste
The present study aimed at an evaluation of the protoscolicidal potential of methanolic extracts of three herbs; Ferula asafoetida (dried latex), Trachyspermum ammi (fruits) and Hippophae salicifolia (leaves) at three different concentrations (10, 20 and 30 mg/mL) for 20, 40 and 60 minute treatment intervals, with respect to standard allopathic drug albendazole. The in-vitro viability of the protoscolices was assessed by the Eosin exclusion method. The slope of mortality and lethal concentration for 50% (LC50) was determined from the regression graphs of the probit mortality of protoscolices plotted against log values of increasing concentrations of herbal extracts for 60 minute treatment intervals. The percentage of mortality caused by various extracts at concentrations ranging from 10-30 mg/mL varied from 29.54-97.76% with maximum mortality of 97.76, 97.30 and 81.91% recorded with methanolic extracts of F. asafoetida, T. ammi and H. salicifolia, respectively. Among all the extracts, the highest protoscolicidal activity was exhibited by F. asafoetida at 20 and 30 mg/mL concentrations in the 60 (97.16%) and 40/60 minutes (97.20% and 97.76%) treatments, respectively, and it showed a minimum LC50 value of 0.204, followed by T. ammi at 0.933. As compared to the standard allopathic drug, albendazole, the methanolic extracts of F. asafoetida and T. ammi exhibited better or comparable protoscolicidal activities.Cilj je istraživanja bila procjena protoskolicidnog potencijala metanolnih ekstrakata triju biljaka: Ferula asafoetida (sušena smola), Trachyspermum ammi (voće) i Hippophae salicifolia (lišće) u trima različitim koncentracijama (10, 20 i 30 mg/mL) u 20, 40 i 60-minutnim pokusnim intervalima u odnosu na standardni alopatski lijek albendazol. In vitro vitalnost protoskoleksa procijenjena je metodom isključivanja eozina. Krivulja pomora i smrtonosne koncentracije za 50 % (LC50) određena je iz regresijskih grafikona mortaliteta protoskoleksa u odnosu na log vrijednosti rastućih koncentracija biljnih ekstrakata tijekom 60-minutnog intervala. Pomor uzrokovan različitim ekstraktima u koncentracijama od 10 do 30 mg/mL varirao je od 29,54 do 97,76 % s najvišim postotkom od 97,76, 97,30 i 81,91 % u slučaju metanolnih ekstrakata F. asafoetida, T. ammi i H. salicifolia. Od svih primijenjenih ekstrakata najvišu protoskolicidnu aktivnost imala je F. asafoetida u koncentracijama od 20 i 30 mg/mL tijekom tretmana od 60 (97,16 %) i 40/60 minuta (97,20 i 97,76%), te je pokazala minimalnu vrijednost LC50 od 0,204, praćenu s T. ammi od 0,933. Usporedbom sa standardnim antiparazitikom albendazolom, metanolni ekstrakti biljaka F. asafoetida i T. ammi ostvarili su bolji ili slični protoskolicidni učinak
Quantum cohomology via vicious and osculating walkers
We relate the counting of rational curves intersecting Schubert varieties of the Grassmannian to the counting of certain non-intersecting lattice paths on the cylinder, so-called vicious and osculating walkers. These lattice paths form exactly solvable statistical mechanics models and are obtained from solutions to the Yang–Baxter equation. The eigenvectors of the transfer matrices of these models yield the idempotents of the Verlinde algebra of the gauged u^(n)k -WZNW model. The latter is known to be closely related to the small quantum cohomology ring of the Grassmannian. We establish further that the partition functions of the vicious and osculating walker model are given in terms of Postnikov’s toric Schur functions and can be interpreted as generating functions for Gromov–Witten invariants. We reveal an underlying quantum group structure in terms of Yang–Baxter algebras and use it to give a generating formula for toric Schur functions in terms of divided difference operators which appear in known representations of the nil-Hecke algebra
Statistical Interpretation of Joint Multiplicity Distributions of Neutrons and Charged Particles
Experimental joint multiplicity distributions of neutrons and charged
particles emitted in complex nuclear reactions provide an important test of
theoretical models. The method is applied to test three different theoretical
models of nuclear multi-fragmentation, two of which fail the test. The
measurement of neutrons is decisive in distinguishing between the Berlin and
Copenhagen models of nuclear multi-fragmentation and challenges the
interpretation of pseudo- Arrhenius plots. Statistical-model evaporation
calculations with GEMINI give a good reproduction first and second moments of
the experimental multiplicity correlations.Comment: 12 pages, 3 figures Added GEMINI calculations of multiplicity
correlations Added brief discussion of how neutron emission is treated in
MMM
Deformation effects in Ni nuclei produced in Si+Si at 112 MeV
Velocity and energy spectra of the light charged particles (protons and
-particles) emitted in the Si(E = 112 MeV) + Si
reaction have been measured at the Strasbourg VIVITRON Tandem facility. The
ICARE charged particle multidetector array was used to obtain exclusive spectra
of the light particles in the angular range 15 - 150 degree and to determine
the angular correlations of these particles with respect to the emission angles
of the evaporation residues. The experimental data are analysed in the
framework of the statistical model. The exclusive energy spectra of
-particles emitted from the Si + Si compound system are
generally well reproduced by Monte Carlo calculations using spin-dependent
level densities. This spin dependence approach suggests the onset of large
deformations at high spin. A re-analysis of previous -particle data
from the Si + Si compound system, using the same spin-dependent
parametrization, is also presented in the framework of a general discussion of
the occurrence of large deformation effects in the A ~ 60 mass region.Comment: 25 pages, 6 figure
Centrality Dependence of Neutral Pion Production in 158 A GeV Pb + Pb Collisions
The production of neutral pions in 158AGeV Pb+Pb collisions has been studied
in the WA98 experiment at the CERN SPS. Transverse momentum spectra are studied
for the range 0.3 GeV/c < mT-m0 < 4.0 GeV/c. The results for central collisions
are compared to various models. The centrality dependence of the neutral pion
spectral shape and yield is investigated. An invariance of the spectral shape
and a simple scaling of the yield with the number of participating nucleons is
observed for centralities with greater than about 30 participating nucleons
which is most naturally explained by assuming an equilibrated system.Comment: 5 pages, Latex, including 3 eps figures, submitted to Phys.Rev.Lett;
updated pQCD comparison due to new input from the author, updated references,
corrected plotting error in figure
Systematics of Inclusive Photon Production in 158 AGeV Pb Induced Reactions on Ni, Nb, and Pb Targets
The multiplicity of inclusive photons has been measured on an event-by-event
basis for 158 AGeV Pb induced reactions on Ni, Nb, and Pb targets. The
systematics of the pseudorapidity densities at midrapidity (rho_max) and the
width of the pseudorapidity distributions have been studied for varying
centralities for these collisions. A power law fit to the photon yield as a
function of the number of participating nucleons gives a value of 1.13+-0.03
for the exponent. The mean transverse momentum, , of photons determined
from the ratio of the measured electromagnetic transverse energy and photon
multiplicity, remains almost constant with increasing rho_max. Results are
compared with model predictions.Comment: 16 pages including 4 figure
Highly deformed Ca configurations in Si + C
The possible occurrence of highly deformed configurations in the Ca
di-nuclear system formed in the Si + C reaction is investigated
by analyzing the spectra of emitted light charged particles. Both inclusive and
exclusive measurements of the heavy fragments (A 10) and their
associated light charged particles (protons and particles) have been
made at the IReS Strasbourg {\sc VIVITRON} Tandem facility at bombarding
energies of Si) = 112 MeV and 180 MeV by using the {\sc ICARE}
charged particle multidetector array. The energy spectra, velocity
distributions, and both in-plane and out-of-plane angular correlations of light
charged particles are compared to statistical-model calculations using a
consistent set of parameters with spin-dependent level densities. The analysis
suggests the onset of large nuclear deformation in Ca at high spin.Comment: 33 pages, 11 figure
Thecamoebians (Testate Amoebae) Straddling the Permian-Triassic Boundary in the Guryul Ravine Section, India: Evolutionary and Palaeoecological Implications
Exceptionally well-preserved organic remains of thecamoebians (testate amoebae) were preserved in marine sediments that straddle the greatest extinction event in the Phanerozoic: the Permian-Triassic Boundary. Outcrops from the Late Permian Zewan Formation and the Early Triassic Khunamuh Formation are represented by a complete sedimentary sequence at the Guryul Ravine Section in Kashmir, India, which is an archetypal Permian-Triassic boundary sequence. Previous biostratigraphic analysis provides chronological control for the section, and a perspective of faunal turnover in the brachiopods, ammonoids, bivalves, conodonts, gastropods and foraminifera. Thecamoebians were concentrated from bulk sediments using palynological procedures, which isolated the organic constituents of preserved thecamoebian tests. The recovered individuals demonstrate exceptional similarity to the modern thecamoebian families Centropyxidae, Arcellidae, Hyalospheniidae and Trigonopyxidae, however, the vast majority belong to the Centropyxidae. This study further confirms the morphologic stability of the thecamoebian lineages through the Phanerozoic, and most importantly, their apparent little response to an infamous biological crisis in Earth's history
Scaling of Particle and Transverse Energy Production in 208Pb+208Pb collisions at 158 A GeV
Transverse energy, charged particle pseudorapidity distributions and photon
transverse momentum spectra have been studied as a function of the number of
participants (N_{part}) and the number of binary nucleon-nucleon collisions
(N_{coll}) in 158 A GeV Pb+Pb collisions over a wide impact parameter range. A
scaling of the transverse energy pseudorapidity density at midrapidity as
N_{part}^{1.08 \pm 0.06} and N_{coll}^{0.83 \pm 0.05} is observed. For the
charged particle pseudorapidity density at midrapidity we find a scaling as
N_{part}^{1.07 \pm 0.04} and N_{coll}^{0.82 \pm 0.03}. This faster than linear
scaling with N_{part} indicates a violation of the naive Wounded Nucleon Model.Comment: 13 pages, 16 figures, submitted to European Physical Journal C
(revised results for scaling exponents
A Preshower Photon Multiplicity Detector for the WA98 Experiment
A high granularity preshower detector has been fabricated and installed in the WA98 Experiment at the CERN SPS for measuring the spatial distribution of photons produced in the forward region in lead ion induced interactions. Photons are counted by detecting the preshower signal in plastic scintillator pads placed behind a 3 radiation length thick lead converter and applying a threshold on the scintillator signal to reject the minimum ionizing particles. Techniques to improve the imaging of the fibre and performance of the detector in the high multiplicity environment of lead-lead collisions are described. Using Monte-Carlo simulation methods and test beam data of pi- and e- at various energies the photon counting efficiency is estimated to be 68% for central and 73% for peripheral Pb+Pb collisions
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