1,407 research outputs found
ANTIBACTERIAL EFFECTIVENESS OF PROSOPIS JULIFLORA AGAINST AEROBIC AND ANAEROBIC BACTERIA
Objective: The aim of this study is to analyse the antibacterial effectiveness of the leaf extract of Prosopis juliflora against aerobic and anaerobic bacteria and the objectives include maintaining the culture of Clostridium perfringens ATCC 3624, Staphylococcus aureus ATCC 25923, E. coli ATCC 25922 and to obtain an extract from the leaves of Prosopis juliflora by water extraction method. Agar cup diffusion testing is carried out to test the effectiveness of the extracted herb against the isolated strains of the above-mentioned bacteria.
Methods: Cross-sectional study was conducted for 6 mo in the Clinical Microbiology Laboratory at SMCH. Extract from the leaves of Prosopis juliflora was collected by a water extraction method. Isolation of Clostridium perfringens (from RCMB), Staphylococcus aureus and Escherichia coli were done, following which the agar cup diffusion method was performed in which the collected extracts were placed as discs in the agar plate which had been inoculated with the strains of the isolated bacteria. The agar plate was then incubated anaerobically. Agar cup diffusion method is considered as a primary method to determine the antimicrobial effectiveness of the bacteria.
Results: The leaf extract of Prosopis juliflora was found to be effective against both aerobic and anaerobic bacterial strains.
Conclusion: Based on the work, the effectiveness of Prosopis juliflora was determined and the mechanism of susceptibility was identified. With future research works in the field, many such natural herbal extracts can be proven to be effective against many pathogenic microorganisms
Magellan Spectroscopy of AGN Candidates in the COSMOS Field
We present spectroscopic redshifts for the first 466 X-ray and radio-selected
AGN targets in the 2 deg^2 COSMOS field. Spectra were obtained with the IMACS
instrument on the Magellan (Baade) telescope, using the nod-and-shuffle
technique. We identify a variety of Type 1 and Type 2 AGN, as well as red
galaxies with no emission lines. Our redshift yield is 72% down to i_AB=24,
although the yield is >90% for i_AB<22. We expect the completeness to increase
as the survey continues. When our survey is complete and additional redshifts
from the zCOSMOS project are included, we anticipate ~1100 AGN with redshifts
over the entire COSMOS field. Our redshift survey is consistent with an
obscured AGN population that peaks at z~0.7, although further work is necessary
to disentangle the selection effects.Comment: 19 pages, 14 figures. Accepted to ApJS special COSMOS issue. The full
electronic version of Table 2 can be found at
http://shaihulud.as.arizona.edu/~jtrump/tab2.tx
The evolution of clustering and bias in the galaxy distribution
This paper reviews the measurements of galaxy correlations at high redshifts,
and discusses how these may be understood in models of hierarchical
gravitational collapse. The clustering of galaxies at redshift one is much
weaker than at present, and this is consistent with the rate of growth of
structure expected in an open universe. If , this observation would
imply that bias increases at high redshift, in conflict with observed
values for known high- clusters. At redshift 3, the population of
Lyman-limit galaxies displays clustering which is of similar amplitude to that
seen today. This is most naturally understood if the Lyman-limit population is
a set of rare recently-formed objects. Knowing both the clustering and the
abundance of these objects, it is possible to deduce empirically the
fluctuation spectrum required on scales which cannot be measured today owing to
gravitational nonlinearities. Of existing physical models for the fluctuation
spectrum, the results are most closely matched by a low-density spatially flat
universe. This conclusion is reinforced by an empirical analysis of CMB
anisotropies, in which the present-day fluctuation spectrum is forced to have
the observed form. Open models are strongly disfavoured, leaving CDM
as the most successful simple model for structure formation.Comment: Invited review at the Royal Society Meeting `Large-scale structure in
the universe', London, March 1998. 20 Pages LaTe
Identifying dynamically young galaxy groups via wide-angle tail galaxies: A case study in the COSMOS field at z=0.53
We present an analysis of a wide-angle tail (WAT) radio galaxy located in a
galaxy group in the COSMOS field at a redshift of z=0.53 (hereafter CWAT-02).
We find that the host galaxy of CWAT-02 is the brightest galaxy in the group,
although it does not coincide with the center of mass of the system. Estimating
a) the velocity of CWAT-02, relative to the intra-cluster medium (ICM), and b)
the line-of-sight peculiar velocity of CWAT-02's host galaxy, relative to the
average velocity of the group, we find that both values are higher than those
expected for a dominant galaxy in a relaxed system. This suggests that
CWAT-02's host group is dynamically young and likely in the process of an
ongoing group merger. Our results are consistent with previous findings showing
that the presence of a wide-angle tail galaxy in a galaxy group or cluster can
be used as an indicator of dynamically young non-relaxed systems. Taking the
unrelaxed state of CWAT-02's host group into account, we discuss the impact of
radio-AGN heating from CWAT-02 onto its environment, in the context of the
missing baryon problem in galaxy groups. Our analysis strengthens recent
results suggesting that radio-AGN heating may be powerful enough to expel
baryons from galaxy groups.Comment: 8 pages, 6 figures, 1 table. Accepted for publication in Ap
Literacy practices of primary education children in Andalusia (Spain): a family-based perspective
Primary school children develop literacy practices in various domains and situations in everyday life.
This study focused on the analysis of literacy practices of children aged 8â12 years from the perspec-
tive of their families. 1,843 families participated in the non-experimental explanatory study. The
children in these families speak Spanish as a first language and are schooled in this language. The
instrument used was a self-report questionnaire about childrenâs home-literacy practices. The data
obtained were analysed using categorical principal components analysis (CATPCA) and analysis of
variance (ANOVA). The results show the complex relationship between literacy practices developed
by children in the domains of home and school and the limited development of a literacy-promoting
âthird spaceâ. In conclusion, the families in our study had limited awareness of their role as literacy-
promoting agents and thought of literacy learning as restricted to formal or academic spaces
A low escape fraction of ionizing photons of L>L* Lyman break galaxies at z=3.3
We present an upper limit for the relative escape fraction (f_{esc}^{rel}) of
ionizing radiation at z~3.3 using a sample of 11 Lyman Break Galaxies (LBGs)
with deep imaging in the U band obtained with the Large Binocular Camera,
mounted on the prime focus of the Large Binocular Telescope. We selected 11
LBGs with secure redshift in the range 3.27<z<3.35, from 3 independent fields.
We stacked the images of our sources in the R and U band, which correspond to
an effective rest-frame wavelength of 1500\AA and 900\AA respectively,
obtaining a limit in the U band image of >=30.7(AB)mag at 1 sigma. We derive a
1 sigma upper limit of f_{esc}^{rel}~5%, which is one of the lowest values
found in the literature so far at z~3.3. Assuming that the upper limit for the
escape fraction that we derived from our sample holds for all galaxies at this
redshift, the hydrogen ionization rate that we obtain (Gamma_{-12}<0.3 s^{-1})
is not enough to keep the IGM ionized and a substantial contribution to the UV
background by faint AGNs is required. Since our sample is clearly still limited
in size, larger z~3 LBG samples, at similar or even greater depths are
necessary to confirm these results on a more firm statistical basis.Comment: 15 pages, 2 figures, 1 table, accepted for publication in Ap
Current drag in capacitevly coupled Luttinger constrictions
We study the current drag in the system of two electrostatically coupled
finite 1D electron channels. We present the perturbation theory results along
with the results for two non-perturbative regimes. It is shown that the drag
may become absolute, that is, the currents in the channels are equal in a
finite window of the bias voltages.Comment: 4 pages RevTeX, 3 postscript figure
Anisotropy and periodicity in the density distribution of electrons in a quantum-well
We use low temperature near-field optical spectroscopy to image the electron
density distribution in the plane of a high mobility GaAs quantum well. We find
that the electrons are not randomly distributed in the plane, but rather form
narrow stripes (width smaller than 150 nm) of higher electron density. The
stripes are oriented along the [1-10 ] crystal direction, and are arranged in a
quasi-periodic structure. We show that elongated structural mounds, which are
intrinsic to molecular beam epitaxy, are responsible for the creation of this
electron density texture.Comment: 10 pages, 3 figure
The XMM-Newton wide-field survey in the COSMOS field. IV: X-ray spectral properties of Active Galactic Nuclei
We present a detailed spectral analysis of point-like X-ray sources in the
XMM-COSMOS field. Our sample of 135 sources only includes those that have more
than 100 net counts in the 0.3-10 keV energy band and have been identified
through optical spectroscopy. The majority of the sources are well described by
a simple power-law model with either no absorption (76%) or a significant
intrinsic, absorbing column (20%).As expected, the distribution of intrinsic
absorbing column densities is markedly different between AGN with or without
broad optical emission lines. We find within our sample four Type-2 QSOs
candidates (L_X > 10^44 erg/s, N_H > 10^22 cm^-2), with a spectral energy
distribution well reproduced by a composite Seyfert-2 spectrum, that
demonstrates the strength of the wide field XMM/COSMOS survey to detect these
rare and underrepresented sources.Comment: 16 pages, ApJS COSMOS Special Issue, 2007 in press. The
full-resolution version is available at
http://www.mpe.mpg.de/XMMCosmos/PAPERS/mainieri_cosmos.ps.g
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