2,792 research outputs found
Evidence against strong correlation in 4d transition metal oxides, CaRuO3 and SrRuO3
We investigate the electronic structure of 4d transition metal oxides, CaRuO3
and SrRuO3. The analysis of the photoemission spectra reveals significantly
weak electron correlation strength (U/W ~ 0.2) as expected in 4d systems and
resolves the long standing issue that arose due to the prediction of large U/W
similar to 3d-systems. It is shown that the bulk spectra, thermodynamic
parameters and optical properties in these systems can consistently be
described using first principle approaches. The observation of different
surface and bulk electronic structures in these weakly correlated 4d systems is
unusual.Comment: 4 pages, 4 figure
Observation of particle hole asymmetry and phonon excitations in non-Fermi liquid systems: A high-resolution photoemission study of ruthenates
We investigate the temperature evolution of the electronic states in the
vicinity of the Fermi level of a non-Fermi liquid (NFL) system, CaRuO3 using
ultra high-resolution photoemission spectroscopy; isostructural SrRuO3
exhibiting Fermi liquid behavior despite similar electron interaction
parameters as that of CaRuO3, is used as a reference. High-energy resolution in
this study helps to reveal particle-hole asymmetry in the excitation spectra of
CaRuO3 in contrast to that in SrRuO3. In addition, we observe signature of
phonon excitations in the photoemission spectra of CaRuO3 at finite
temperatures while these are weak in SrRuO3.Comment: 4 pages including 3 figure
Observation of R-Band Variability of L Dwarfs
We report, for the first time, photometric variability of L dwarfs in
band. Out of three L1 dwarfs (2MASS 1300+19, 2MASS 1439+19, and 2MASS 1658+70)
observed, we have detected R band variability in 2MASS 1300+19 and 2MASS
1439+19. The objects exhibit variability of amplitude ranging from 0.01 mag to
0.02 mag. Object 2MASS 1658+70, turns out to be non-variable in both and
band. However, more observations are needed to infer its variability. No
periodic behaviour in the variability is found from the two L1 dwarfs that are
variable. All the three L1 dwarfs have either negligible or no
activity. In the absence of any direct evidence for the presence of
sufficiently strong magnetic field, the detection of polarization at the
optical favors the presence of dust in the atmosphere of L dwarfs. We suggest
that the observed band photometric variability is most likely due to
atmospheric dust activity.Comment: 13 pages (latex, aastex style) including 3 eps figures. Accepted for
publication in The Astrophysical Journal Letter
Micellar Aggregates of Gemini Surfactants: Monte Carlo Simulation of a Microscopic Model
We propose a "microscopic" model of gemini surfactants in aqueous solution.
Carrying out extensive Monte Carlo simulations, we study the variation of the
critical micellar concentration (CMC) of these model gemini surfactants with
the variation of the (a) length of the spacer connecting the two hydrophilic
heads, (b) length of the hydrophobic tail and (c) the bending rigidity of the
hydrocarbon chains forming the spacer and the tail; some of the trends of
variation are counter-intuitive but are in excellent agreement with the
available experimental results. Our simulations also elucidate the dependence
of the shapes of the micellar aggregates and the magnitude of the CMC on the
geometrical shape and size of the surfactant molecules and the electrical
charge on the hydrophilic heads
Hysterosalpingography (HSG), hysteroscopy and laparoscopic evaluation of female genital tract of patient attending tertiary infertility centre and correlation of various modalities
Background: Hysterosalpingogarphy (HSG) has traditionally been the first line of investigation anatomy and contour of uterine cavity along with fallopian tube and its patency. Because of limitations of HSG, video endoscopic evaluation of endometrial and peritoneal cavity by diagnostic hysteroscopy and laparoscopy can diagnose many subtle and obvious pathologies in evaluation of infertile couple. To know this difference author studied the efficacy of HSG along with diagnostic laparohysteroscopy.Methods: HSG, Diagnostic Hysteroscopy and Laparoscopy were performed on a group of 50 Patient of primary and secondary infertility. Findings of HSG, Hysteroscopy and Laparoscopy were computed, analyzed and corelated.Results: HSG showed a false positive rate of 25% for tubal factor and false negative 12% for uterine factors when compared with hysteroscopic and laparoscopic findings. The sensitivity of HSG was 75% and specificity was 88 % when compared with Hysteroscopic and Laparoscopic findings. Among various abnormality detected during the present study were, congenital anomaly 7(14%), Asherman syndrome 5 (10%), Tubal factor defect 6(12%), fibroid 3(6%) and Pelvi-inflammatory disease in 7(14%) of cases.Conclusions: Though HSG is a simple procedure for detecting abnormality of female genital tract, due to its low specificity and sensitivity hysterolaparoscopy should be complemented during infertility work up in all patient
Spin-Hall effect in triplet chiral superconductors and graphene
We study spin-Hall effects in time-reversal symmetry (TRS) broken systems
such as triplet chiral superconductors and TRS preserved ones such as graphene.
For chiral triplet superconductors, we show that the edge states carry a
quantized spin-Hall current in response to an applied Zeeman magnetic field
along the vector \cite{leggett1}, whereas the edge spin-current for
is screened by the condensate. We also derive the bulk
spin-Hall current for chiral triplet superconductors for arbitrary relative
orientation of and and discuss its relation with the edge
spin-current. For TRS invariant system graphene, we show that the bulk
effective action, unlike its TRS broken counterparts, does not support a SU(2)
Hopf term but allows a crossed Hopf term in the presence of an external
electromagnetic field, which yields a quantized bulk spin-Hall current in
response to an electric field. We also present an analytical solution of the
edge problem for armchair edges of graphene and contrast the properties of
these edge states with their time reversal symmetry broken counterparts in
chiral superconductors. We propose possible experiments to test our results.Comment: v2; minor changes, additional ref
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