Support structure for irradiated elements Patent

Supporting structure for simultaneous exposure of pellets to X ray

Test fixture for pellet-like electrical elements

Fixture for simultaneously supporting several components for electrical testin

Multicolor Photometry of the Vela Pulsar

Multicolor photometry of the Vela pulsar (PSR B0833-45), updated by recent HST/WFPC2 observations obtained in the 555W, 675W and 814W filters, is presented. The available data provide the best characterization so far of the pulsar spectral shape, which is dominated by a flat power law continuum with spectral index \alpha = -0.2 +/- 0.2, consistent with the extrapolation in the optical domain of the power law component of the X-ray spectrum detected by Chandra. In addition, a marginally significant dip (~ 3 sigma) seems to be present at about 6500 AA. Spectroscopic observations with the VLT, now in progress, will undoubtly provide a much better assessment of the reality and characteristics of this feature.Comment: 4 pages, LaTex, 2 Postscript figures. Astronomy & Astrophysics, accepte

Don't forget primary progressive aphasia for anti-amyloid drugs: An estimation of eligible patients from the Lausanne Memory Center registry.

The study recently published on the clinical effect of lecanemab in early Alzheimer's disease (AD) only includes patients with amnestic presentation. However, a significant portion of AD patients presents a non-amnestic phenotype of AD, such as primary progressive aphasia (PPA) and could benefit of rather than on lecanemab. Therefore, we conducted a 10-year retrospective study at the Leenaards Memory Center in Lausanne (Switzerland) to identify how many PPA patients would be eligible for lecanemab. Among 54 patients with PPA, we identified 11 (20%) eligible patients. Furthermore, almost half of the 18 patients with logopenic variant would be eligible for lecanemab treatment

Search for the Optical Counterpart of the Vela Pulsar X-ray Nebula

Observations of the Vela pulsar region with the Chandra X-ray observatory have revealed the fine structure of its synchrotron pulsar-wind nebula (PWN), which showed an overall similarity with the Crab PWN. However, contrary to the Crab, no firm detection of the Vela PWN in optical has been reported yet. To search for the optical counterpart of the X-ray PWN, we analyzed deep optical observations performed with different telescopes. We compared the optical images with those obtained with the Chandra ACIS to search for extended emission patterns which could be identified as counterparts of the X-ray nebula elements. Although some features are seen in the optical images, we find no correlation with the X-ray structure. Thus, we conclude that the diffuse optical emission is more likely associated with filaments in the host Vela SNR. The derived upper limits on the optical flux from the PWN are compatibile, within the uncertainties, with the values expected on the basis of the extrapolations of the X-ray data.Comment: 19 pages, 6 figures. Accepted for publication in Ap

The Optical Spectrum of the Vela Pulsar

Our knowledge of the optical spectra of Isolated Neutron Stars (INSs) is limited by their intrinsic faintness. Among the fourteen optically identified INSs, medium resolution spectra have been obtained only for a handful of objects. No spectrum has been published yet for the Vela pulsar (PSR B0833-45), the third brightest (V=23.6) INS with an optical counterpart. Optical multi-band photometry underlines a flat continuum.In this work we present the first optical spectroscopy observations of the Vela pulsar, performed in the 4000-11000 A spectral range.Our observations have been performed at the ESO VLT using the FORS2 instrument. The spectrum of the Vela pulsar is characterized by a flat power-law (alpha = -0.04 +/- 0.04), which compares well with the values obtained from broad-band photometry. This confirms, once more, that the optical emission of Vela is entirely of magnetospheric origin. The comparison between the optical spectral indeces of rotation-powered INSs does not show evidence for a spectral evolution suggesting that, as in the X-rays, the INS aging does not affect the spectral properties of the magnetospheric emission. At the same time, the optical spectral indeces are found to be nearly always flatter then the X-rays ones, clearly suggesting a general spectral turnover at lower energies.Comment: 7 pages, 8 figures, accepted for publication in A&

The distance to the Vela pulsar gauged with HST parallax oservations

The distance to the Vela pulsar (PSR B0833-45) has been traditionally assumed to be 500 pc. Although affected by a significant uncertainty, this value stuck to both the pulsar and the SNR. In an effort to obtain a model free distance measurement, we have applied high resolution astrometry to the pulsar V~23.6 optical counterpart. Using a set of five HST/WFPC2 observations, we have obtained the first optical measurement of the annual parallax of the Vela pulsar. The parallax turns out to be 3.4 +/- 0.7 mas, implying a distance of 294(-50;+76) pc, i.e. a value significantly lower than previously believed. This affects the estimate of the pulsar absolute luminosity and of its emission efficiency at various wavelengths and confirms the exceptionally high value of the N_e towards the Vela pulsar. Finally, the complete parallax data base allows for a better measurement of the Vela pulsar proper motion (mu_alpha(cos(delta))=-37.2 +/- 1.2 mas/yr; mu_delta=28.2 +/- 1.3 mas/yr after correcting for the peculiar motion of the Sun) which, at the parallax distance, implies a transverse velocity of ~65 km/s. Moreover, the proper motion position angle appears specially well aligned with the axis of symmetry of the X-ray nebula as seen by Chandra. Such an alignment allows to assess the space velocity of the Vela pulsar to be ~81 km/s.Comment: LaTeX, 21 pages, 5 figures. Accepted for publication in Ap

Unpulsed UBV Optical Emission from the Crab Pulsar

Based on observations of the Crab pulsar using the TRIFFID high speed imaging photometer in the UBV bands using the Special Astrophysical Observatory's 6m telescope in the Russian Caucasus, we report the detection of pronounced emission during the so-called `off' phase of emission. Following de-extinction, this unpulsed component of emission is shown to be consistent with a power law with an exponent of alpha = -0.60 +/- 0.37, the uncertainty being dominated by the error associated with the independent CCD photometry used to reference the TRIFFID data. This suggests a steeper power law form than that reported elsewhere in the literature for the total integrated spectrum, which is essentially flat with alpha ~ 0.1, although the difference in this case is only significant at the ~ 2 sigma level. Deeper reference integrated and TRIFFID phase-resolved photometry in these bands in conjunction with further observations in the UV and R region would constrain this fit further.Comment: 26 pages, 2 figures, uses aasms4.sty, accepted for publication in the Astrophysical Journa

Implications of the Optical Observations of Neutron Stars

We show that observations of pulsars with pulsed optical emission indicate that the peak flux scales according to the magnetic field strength at the light cylinder. The derived relationships indicate that the emission mechanism is common across all of the observed pulsars with periods ranging from 33ms to 385 ms and ages of 1000-300,000 years. It is noted that similar trends exist for $\gamma$ ray pulsars. Furthermore the model proposed by Pacini (1971) and developed by Pacini and Salvati (1983,1987) still has validity and gives an adequate explanation of the optical phenomena.Comment: 23 pages, 6 figures, accepted for publication in the Astrophysical Journa

Dopaminergic system modulation, behavioral changes, and oxidative stress after neonatal administration of pyrethroids

Pyrethroids are a class of insecticides involved in different neurological disorders. They cross the blood–brain barrier and exert their effect on dopaminergic system, contributing to the burden of oxidative stress in Parkinson’s disease through several pathways. The aim of the present study was to evaluate the effect of neonatal exposition to permethrin and cypermethrin (1/10 of DL50) in rats from the eighth to the fifteenth day of life. Open-field studies showed increased spontaneous locomotor activity in the groups treated with permethrin and the one treated with cypermethrin, while a higher number of center entries and time spent in the center was observed for the cypermethrin-treated group. Lower dopamine and higher homovanillic acid levels were measured in the striatum from both treated groups. A reduction of blood glutathione peroxidase content was measured, while no change in blood superoxide dismutase was observed. Carbonyl group formation increased in striatum, but not in erythrocytes. Lipid peroxidation occurred in erythrocytes, but not in striatum. No changes in fluidity at different depths of plasma membrane were measured in striatum or erythrocytes. The activation of monocyte NADPH oxidase by phorbol esters (PMA) shows that superoxide anion production was reduced in the pyrethroid-treated groups compared to the control group. Our studies suggest that neonatal exposition to permethrin or cypermethrin induces long-lasting effects after developmental exposure giving changes in open-field behaviors, striatal monoamine level, and increased oxidative stress. Although the action of pyrethroids on various target cells is different, a preferential interaction with the extracellular side of plasma membrane proteins can be observed