117 research outputs found
Syphilis- The Great Imitator
Syphilis is an infectious disease with Treponema Pallidum being its causative agent. When not treated it can pass through 4 stages: primary, secondary, latent and tertiary. Syphilis has a broad spectrum of skin and mucosal manifestations and can imitate many other skin disease, hence the name ldquo;The great Imitatorrdquo;. The number of patients infected with syphilis has declined dramatically after penicillin invention. Albania has not had a significant number of cases but eruptions has been seen time after time. Herein, we describe 5 cases of suspected syphilis presented at our clinic
1.6 W continuous-wave Raman laser using low-loss synthetic diamond
Low-birefringence (Δn<2x10−6), low-loss (absorption coefficient <0.006cm−1 at 1064nm), single-crystal, synthetic diamond has been exploited in a CW Raman laser. The diamond Raman laser was intracavity pumped within a Nd:YVO4 laser. At the Raman laser wavelength of 1240nm, CW output powers of 1.6W and a slope efficiency with respect to the absorbed diode-laser pump power (at 808nm) of ~18% were measured. In quasi-CW operation, maximum on-time output powers of 2.8W (slope efficiency ~24%) were observed, resulting in an absorbed diode-laser pump power to the Raman laser output power conversion efficiency of 13%
The ion-induced charge-exchange X-ray emission of the Jovian Auroras: Magnetospheric or solar wind origin?
A new and more comprehensive model of charge-exchange induced X-ray emission,
due to ions precipitating into the Jovian atmosphere near the poles, has been
used to analyze spectral observations made by the Chandra X-ray Observatory.
The model includes for the first time carbon ions, in addition to the oxygen
and sulfur ions previously considered, in order to account for possible ion
origins from both the solar wind and the Jovian magnetosphere. By comparing the
model spectra with newly reprocessed Chandra observations, we conclude that
carbon ion emission provides a negligible contribution, suggesting that solar
wind ions are not responsible for the observed polar X-rays. In addition,
results of the model fits to observations support the previously estimated
seeding kinetic energies of the precipitating ions (~0.7-2 MeV/u), but infer a
different relative sulfur to oxygen abundance ratio for these Chandra
observations.Comment: 11 pages, 2 figures, 2 tables, submitted to ApJ Lette
Intracavity Raman conversion of a red semiconductor disk laser using diamond
We demonstrate a diamond Raman laser intracavity-pumped by a red semiconductor disk laser (~675 nm) for laser emission at around 740 nm. Output power up to 82 mW of the Stokes-shifted field was achieved, limited by the available pump power, with an output coupling of 1.5%. We also report wavelength tuning of the diamond Raman laser over 736 - 750 nm
Electronically highly cubic conditions for Ru in alpha-RuCl3
We studied the local Ru 4d electronic structure of alpha-RuCl3 by means of
polarization dependent x-ray absorption spectroscopy at the Ru-L2,3 edges. We
observed a vanishingly small linear dichroism indicating that electronically
the Ru 4d local symmetry is highly cubic. Using full multiplet cluster
calculations we were able to reproduce the spectra excellently and to extract
that the trigonal splitting of the t2g orbitals is -12 meV, i.e.
negligible as compared to the Ru 4d spin-orbit coupling constant. Consistent
with our magnetic circular dichroism measurements, we found that the ratio of
the orbital and spin moments is 2.0, the value expected for a Jeff = 1/2 ground
state. We have thus shown that as far as the Ru 4d local properties are
concerned, alpha-RuCl3 is an ideal candidate for the realization of Kitaev
physics
Nonlinear spectroscopy of excitonic states in transition metal dichalcogenides
Second-harmonic generation (SHG) is a well-known nonlinear spectroscopy
method to probe electronic structure, specifically, in transition metal
dichalcogenide (TMDC) monolayers. This work investigates the nonlinear dynamics
of a strongly excited TMDC monolayer by solving the time evolution equations
for the density matrix. It is shown that the presence of excitons qualitatively
changes the nonlinear dynamics leading, in particular, to a huge enhancement of
the nonlinear signal as a function of the dielectric environment. It is also
shown that the SHG polarization angular diagram and its dependence on the
driving strength are very sensitive to the type of exciton state. This
sensitivity suggests that SHG spectroscopy is a convenient tool for analyzing
the fine structure of excitonic states.Comment: 13 pages, 5 figure
Density Functional Study of Cubic to Rhombohedral Transition in -AlF
Under heating, -AlF undergoes a structural phase transition from
rhombohedral to cubic at temperature around 730 K. The density functional
method is used to examine the =0 energy surface in the structural parameter
space, and finds the minimum in good agreement with the observed rhombohedral
structure. The energy surface and electronic wave-functions at the minimum are
then used to calculate properties including density of states, -point
phonon modes, and the dielectric function. The dipole formed at each fluorine
ion in the low temperature phase is also calculated, and is used in a classical
electrostatic picture to examine possible antiferroelectric aspects of this
phase transition.Comment: A 6-page manuscript with 4 figures and 4 table
Laser spectroscopy of NV- and NV0 colour centres in synthetic diamond
In this paper, we analyse the prospects for using nitrogen-vacancy centre (NV) containing diamond as a laser gain material by measuring its key laser related parameters. Synthetic chemical vapour deposition grown diamond samples with an NV concentration of ~1 ppm have been selected because of their relatively high NV concentration and low background absorption in comparison to other samples available to us. For the samples measured, the luminescence lifetimes of the NV- and NV0 centres were measured to be 8±1 ns and 20±1 ns respectively. The respective peak stimulated emission cross-sections were (3.6±0.1)×10-17 cm2 and (1.7±0.1)×10-17 cm2. These measurements were combined with absorption measurements to calculate the gain spectra for NV- and NV0 for differing inversion levels. Such calculations indicate that gains approaching those required for laser operation may be possible with one of the samples tested and for the NV- centre
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Comparative Analysis and Variability of the Jovian X‐Ray Spectra Detected by the Chandra and XMM‐Newton Observatories
Expanding upon recent work, a more comprehensive spectral model based on charge exchange induced X‐ray emission by ions precipitating into the Jovian atmosphere is used to provide new understanding of the polar auroras. In conjunction with the Xspec spectral fitting software, the model is applied to analyze observations from both Chandra and XMM‐Newton by systematically varying the initial precipitating ion parameters to obtain the best fit model for the observed spectra. In addition to the oxygen and sulfur ions considered previously, carbon is included to discriminate between solar wind and Jovian magnetospheric ion origins, enabled by the use of extensive databases of both atomic collision cross sections and radiative transitions. On the basis of fits to all the Chandra observations, we find that carbon contributes negligibly to the observed polar X‐ray emission suggesting that the highly accelerated precipitating ions are of magnetospheric origin. Most of the XMM‐Newton fits also favor this conclusion with one exception that implies a possible carbon contribution. Comparison among all the spectra from these two observatories in light of the inferred initial energies and relative abundances of precipitating ions from the modeling show that they are significantly variable in time (observation date) and space (north and south polar X‐ray auroras).Astronom
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