600 research outputs found
Dispersion managed mode-locking dynamics in a Ti:Sapphire laser
We present what is to our knowledge the most complete 1-D numerical analysis
of the evolution and the propagation dynamics of an ultrashort laser pulse in a
Ti:Sapphire laser oscillator. This study confirms the dispersion managed model
of mode-locking, and emphasizes the role of the Kerr nonlinearity in generating
mode-locked spectra with a smooth and well-behaved spectral phase. A very good
agreement with preliminary experimental measurements is found.Comment: 11 pages, 4 figures, submitted to Optics Letter
Physics Beyond the Standard Model: Focusing on the Muon Anomaly
We present a model based on the implication of an exceptional E_{6}-GUT
symmetry for the anomalous magnetic moment of the muon. We follow a particular
chain of breakings with Higgses in the 78 and 351 representations. We analyse
the radiative correction contributions to the muon mass and the effects of the
breaking of the so-called Weinberg symmetry. We also estimate the range of
values of the parameters of our model.Comment: 14 RevTeX pages, 5 figure
Proper Motions of H-alpha filaments in the Supernova Remnant RCW 86
We present a proper motion study of the eastern shock-region of the supernova
remnant RCW 86 (MSH 14-63, G315.4-2.3), based on optical observations carried
out with VLT/FORS2 in 2007 and 2010. For both the northeastern and southeastern
regions, we measure an average proper motion of H-alpha filaments of 0.10 +/-
0.02 arcsec/yr, corresponding to 1200 +/- 200 km/s at 2.5kpc. There is
substantial variation in the derived proper motions, indicating shock
velocities ranging from just below 700 km/s to above 2200 km/s.
The optical proper motion is lower than the previously measured X-ray proper
motion of northeastern region. The new measurements are consistent with the
previously measured proton temperature of 2.3 +/- 0.3 keV, assuming no
cosmic-ray acceleration. However, within the uncertainties, moderately
efficient (< 27 per cent) shock acceleration is still possible. The combination
of optical proper motion and proton temperature rule out the possibility that
RCW 86 has a distance less than 1.5kpc.
The similarity of the proper motions in the northeast and southeast is
peculiar, given the different densities and X-ray emission properties of the
regions. The northeastern region has lower densities and the X-ray emission is
synchrotron dominated, suggesting that the shock velocities should be higher
than in the southeastern, thermal X-ray dominated, region. A possible solution
is that the H-alpha emitting filaments are biased toward denser regions, with
lower shock velocities. Alternatively, in the northeast the shock velocity may
have decreased rapidly during the past 200yr, and the X-ray synchrotron
emission is an afterglow from a period when the shock velocity was higher.Comment: Accepted for publication in MNRA
Atg21p is essential for macropexophagy and microautophagy in the yeast Hansenula polymorpha
AbstractATG genes are required for autophagy-related processes that transport proteins/organelles destined for proteolytic degradation to the vacuole. Here, we describe the identification and characterisation of the Hansenula polymorpha ATG21 gene. Its gene product Hp-Atg21p, fused to eGFP, had a dual location in the cytosol and in peri-vacuolar dots. We demonstrate that Hp-Atg21p is essential for two separate modes of peroxisome degradation, namely glucose-induced macropexophagy and nitrogen limitation-induced microautophagy. In atg21 cells subjected to macropexophagy conditions, sequestration of peroxisomes tagged for degradation is initiated but fails to complete
Characterization of soils in an area of prescribed fire
The prescribed fire is a technique that is often used, it has several advantages. Pedological and
hydropedological techniques were tested to assess the prescribed fire changes may cause in
soils. This work was performed in Tresminas area (Vila Pouca de Aguiar, Northern Portugal),
during February and March 2011.
In the present study we applied several techniques. For the field sampling was followed the ISO
10381-1[1], ISO 10381-2[2], and FAO rules [3], as well as were used a grid with 17 points for
measuring the soil parameters. During the fire, we have tried to check, with the assistance of the
Portuguese Forestry Authority, some important parameters such as, the propagation speed, the
size of the flame front and the intensity of energy emitted per unit area. Before the fire, was
collected carefully soil disturbed and undisturbed samples for laboratory analysis, and measured
soil water content; we also have placed four sets of thermocouples for measuring soil
temperature. After the fire, were collected the thermocouples and new soil samples; the water
content were measured in the soil and collected ashes.
In the laboratory, after preparing and sieving the samples, were determined the soil particle size.
The soil pH and electrical conductivity in water was also determined. The total carbon (TC) and
inorganic carbon (IC)[4] was measured by a Shimadzu TOC-Vcsn.
The water content in soil has not varied significantly before and after the fire, as well as soil pH
and soil electrical conductivity. The TC and IC did not change, which was expected, since the
fire not overcome the 200° C. Through the various parameters, we determined that the
prescribed fire didn’t affect the soil. The low temperature of the fire and its rapid
implementation that lead to the possible adverse effects caused by the wild fire didn’t occurred
New cathepsin V inhibitor from stems of Bowdichia virgilioides
Bioassay-guided fractionation of Bowdichia virgilioides Kunth, Fabaceae, extracts has led to the isolation of cathepsin V inhibitors. The investigation of the hexane and ethyl acetate extracts allowed the characterization of eleven compounds: lupeol, lupenone, β-sitosterol and stigmasterol in mixture, trans p-coumaric acid ester derivative, syringaresinol, bowdenol, 8-methoxycoumestrol, 3,4-hydroxy-7-methoxyisoflavone, 7,3′-dihydroxy-4′-methoxyisoflavone, and 5,4′-dihydroxy-7′-methoxyisoflavone. Structures of compounds were stablished by 1D and 2D NMR, and MS experiments. Among the isolated compounds, trans p-coumaric acid ester derivative and 8-methoxycoumestrol showed significant inhibition on cathepsin V, which is up to now unexplored. Keywords: Cathepsin, Cysteine peptidases, Inhibitors, Cerrado biom
Insignificant impact of prescribed fire on surface soil in a Pinus pinaster plantation, northern Portugal
Following a prescribed fire in a Pinus pinaster forest site located in the north-west Portugal, monitoring of any changes in selected soil characteristics and soil hydrology was undertaken to assess the effects of burning on the following: pH, electrical conductivity, water content, organic carbon and porosity. Thirty plots were established on a regular grid. At each sample plot before and after the fire, samples were collected (disturbed samples from depths of 0-1cm and 1-5cm; undisturbed core samples from 0-5cm). The results indicate that there was no measurable impact on the properties of the soil following this carefully conducted prescribed fire. The fire only affected the litter layer, as intended. Confirmation of this minimal impact on the soil was provided by regrowth of grasses and herbs already occurring two months after the fire. The implication is, therefore, that provided this wildfire-risk reduction strategy is carried out under existing strict guidelines, any impact on soil quality will be minimal
Suzaku X-Ray Imaging and Spectroscopy of Cassiopeia A
Suzaku X-ray observations of a young supernova remnant, Cassiopeia A, were
carried out. K-shell transition lines from highly ionized ions of various
elements were detected, including Chromium (Cr-Kalpha at 5.61 keV). The X-ray
continuum spectra were modeled in the 3.4--40 keV band, summed over the entire
remnant, and were fitted with a simplest combination of the thermal
bremsstrahlung and the non-thermal cut-off power-law models. The spectral fits
with this assumption indicate that the continuum emission is likely to be
dominated by the non-thermal emission with a cut-off energy at > 1 keV. The
thermal-to-nonthermal fraction of the continuum flux in the 4-10 keV band is
best estimated as ~0.1. Non-thermal-dominated continuum images in the 4--14 keV
band were made. The peak of the non-thermal X-rays appears at the western part.
The peak position of the TeV gamma-rays measured with HEGRA and MAGIC is also
shifted at the western part with the 1-sigma confidence. Since the location of
the X-ray continuum emission was known to be presumably identified with the
reverse shock region, the possible keV-TeV correlations give a hint that the
accelerated multi-TeV hadrons in Cassiopeia A are dominated by heavy elements
in the reverse shock region.Comment: Publ. Astron. Soc. Japan 61, pp.1217-1228 (2009
Different susceptibility of osteosarcoma cell lines and primary cells to treatment with oncolytic adenovirus and doxorubicin or cisplatin
Despite improvements in treatment regimens for osteosarcoma (OS) patients, survival rate has not increased over the last two decades. New treatment modalities are therefore warranted. Preclinical results with conditionally replicative adenoviruses (CRAds) to treat OS are promising. One type of CRAd that was effective against OS cells is Ad5-Δ24RGD. In other types of cancer, CRAds have been shown to interact synergistically with chemotherapeutic agents. Chemotherapy for OS often includes doxorubicin and cisplatin. Therefore, we explored combination treatment of OS cell lines and primary OS cell cultures with Ad5-Δ24RGD and doxorubicin or cisplatin. On OS cell lines, combination treatment was additive to synergistic. Surprisingly, however, on seven of eight primary OS samples no such combination effects were observed. In contrast, in many cases chemotherapy even inhibited CRAd-mediated cell killing. The inhibitory effect of doxorubicin on Ad5-Δ24RGD in primary OS cells appeared to correlate with slow cell growth rate; reduced viral replication and absence of chemotherapy-induced G2 cell cycle arrest. Our results point to the possibility that, at least for OS, virotherapy and chemotherapy should best not be performed simultaneously. In general, our work underscores the importance of testing new genetic anticancer agents and treatment regimens on primary cancer specimens
- …