An Anomalous UV Extension in NGC6251

Deep U-band FOC images of the nuclear region of NGC6251 have revealed a region of extended emission which is most probably radiation scattered from a continuum source in the nucleus. This radiation lies interior to a dust ring, is nearly perpendicular to the radio jet axis, and is seen primarily in the FOC U and b filters. The extension has a low observed polarization($\le 10$), and is unlikely to arise from line emission. We know of no other examples similar to what we have found in NGC 6251, and we offer some tentative explanations. The nuclear morphology shows clear similarities to that seen in the nucleus of NGC 4261 except for the extended U-band radiation.Comment: 14 pages AAStex format + 4 figures; accepted for publication in ApJ Letter

Measurement of macroscopic plasma parameters with a radio experiment: Interpretation of the quasi-thermal noise spectrum observed in the solar wind

The ISEE-3 SBH radio receiver has provided the first systematic observations of the quasi-thermal (plasma waves) noise in the solar wind plasma. The theoretical interpretation of that noise involves the particle distribution function so that electric noise measurements with long antennas provide a fast and independent method of measuring plasma parameters: densities and temperatures of a two component (core and halo) electron distribution function have been obtained in that way. The polarization of that noise is frequency dependent and sensitive to the drift velocity of the electron population. Below the plasma frequency, there is evidence of a weak noise spectrum with spectral index -1 which is not yet accounted for by the theory. The theoretical treatment of the noise associated with the low energy (thermal) proton population shows that the moving electrical antenna radiates in the surrounding plasma by Carenkov emission which becomes predominant at the low frequencies, below about 0.1 F sub P

Evaluación de la hemostasis

We try to explain the coagulation mechanism evaluation through our own clinical experience

Dust detection by the wave instrument on STEREO: nanoparticles picked up by the solar wind?

The STEREO/WAVES instrument has detected a very large number of intense voltage pulses. We suggest that these events are produced by impact ionisation of nanoparticles striking the spacecraft at a velocity of the order of magnitude of the solar wind speed. Nanoparticles, which are half-way between micron-sized dust and atomic ions, have such a large charge-to-mass ratio that the electric field induced by the solar wind magnetic field accelerates them very efficiently. Since the voltage produced by dust impacts increases very fast with speed, such nanoparticles produce signals as high as do much larger grains of smaller speeds. The flux of 10-nm radius grains inferred in this way is compatible with the interplanetary dust flux model. The present results may represent the first detection of fast nanoparticles in interplanetary space near Earth orbit.Comment: In press in Solar Physics, 13 pages, 5 figure

Place-based education

Education reforms are changing teaching methodology and curriculum content. Their focus on standards can lead to positive multidisciplinary learning or it can be too narrow. While some education boards spend the school year reinforcing primarily reading, writing and arithmetic skills within a traditional classroom setting in order to have all students succeed on standardized tests, other schools are embracing place-based education. Place-based education is beneficial for both the schools and for the communities involved. Schools around the world are acknowledging the value of place-based learning and are adopting this method of education and community service into their regular teaching practices. The American School of Barcelona in Spain is one such school

Jet-gas interactions in z~2.5 radio galaxies: evolution of the ultraviolet line and continuum emission with radio morphology

We present an investigation into the nature of the jet-gas interactions in a sample of 10 radio galaxies at 2.3<z<2.9 using deep spectroscopy of the UV line and continuum emission obtained at Keck II and the Very Large Telescope. Kinematically perturbed gas, which we have shown to be within the radio structure in previous publications, is always blueshifted with respect to the kinematically quiescent gas, is usually spatially extended, and is usually detected on both sides of the nucleus. In the three objects from this sample for which we are able to measure line ratios for both the perturbed and quiescent gases, we suggest that the former has a lower ionization state than the latter. We propose that the perturbed gas is part of a jet-induced outflow, with dust obscuring the outflowing gas that lies on the far side of the object. The spatial extent of the blueshifted perturbed gas, typically ~35 kpc, implies that the dust is spatially extended at least on similar spatial scales. We also find interesting interrelationships between UV line, UV continuum and radio continuum properties of this sample.Comment: Accepted for publication in MNRA

Deep spectroscopy of the FUV-optical emission lines from a sample of radio galaxies at z~2.5: metallicity and ionization

We present long-slit NIR spectra, obtained using the ISAAC instrument at the Very Large Telescope, for nine radio galaxies at z~2.5. One-dimensional spectra have been extracted and cross calibrated with optical spectra from the literature to produce line spectra spanning a rest wavelength of ~1200-7000 A. We have also produced a composite of the rest-frame UV-optical line fluxes of powerful, z~2.5 radio galaxies. We have investigated the relative strengths of Ly-alpha, H-beta, H-alpha, HeII 1640 and HeII 4687, and we find that Av can vary significantly from object to object. In addition, we identify new line ratios to calculate electron temperature: [NeV] 1575/[NeV] 3426, [NeIV] 1602/[NeIV] 2423, OIII] 1663/[OIII] 5008 and [OII] 2471/[OII]3728. We model the emission line spectra and conclude they are best explained by AGN-photoionization with the ionization parameter U varying between objects. Single slab photoionization models are unable to reproduce the high- and the low-ionization lines simultaneously: this may be alleviated either by combining two or more single slab photoionization models with different U, or by using mixed-medium models such as those of Binette, Wilson & Storchi-Bergmann (1996). On the basis of NV/NIV] and NIV]/CIV we argue that shocks make a fractional contribution to the ionization of the EELR. We find that in the EELR of z~2 radio galaxies the N/H abundance ratio is close to its solar value. We conclude that N/H and metallicity do not vary by more than a factor of two in our sample. This is consistent with the idea that massive ellipticals are assembled very early in the history of the universe, and then evolve relatively passively up to the present day.Comment: Accepted for publication by MNRA

Estimation des formes du phosphore dans la rivière Venoge en crue

Des échantillons d'eau de rivière ont été prélevés près de l'embouchure de la Venoge, affluent du Léman, au cours de cinq crues survenues entre octobre 1986 et novembre 1987. Les échantillons ont été extraits de grands volumes d'eau à l'aide d'une centrifugeuse à débit continu. La concentration de matières en suspension, et les formes du phosphore de ces échantillons ont été dosés. L'interprétation de ces données, basée sur une méthode de régression progressive, montre que la concentration en phosphore particulaire total peut être estimée par deux paramètres, la fraction de suspensions supérieure à 63 µm et la concentration en phosphore réactif dissous. Par ailleurs, puisqu'il existe des relations statistiques entre le phosphore particulaire total et les autres formes du phosphore particulaire, il est possible d'évaluer la concentration de ces dernières (formes de phosphore apatitique, non apatitique, organique et inorganique). Le phosphore total dissous peut être pareillement estimé en fonction du phosphore réactif dissous. L'estimation des formes du phosphore et ainsi que celle de leur charge en crue peut donc se faire même lorsque le volume des échantillons est limité, c'est-à-dire, lorsque la quantité de matières en suspension n'est pas suffisante pour l'analyse de toutes les formes du phosphore particutaire.In order to gain a better understanding of phosphorus transport in a storm-dependent river system, water samples were collected near the mouth of the River Venoge, Switzerlang, during five storm events between october 1986 and november 1987. Suspended sediment (SS) was extracted from large-volume water samples by continuous flow centrifugation. Soluble and particulate forms of phosphorus were subsequently analysed with the centrifuged and filtered (0.45 µm) waters, and freeze-dried SS in a < 63 µm fraction.However, the sampling usually performed at more than 4-hour intervals could not guarantee that no information had been missed, for example, the instantaneous fluctuation of soluble reactive phosphorus (SRP) during the events. Although more frequent sampling using an auto-sampler is feasible, the small volume of raw water cannot provide sufficient sediment for all the analyses of phosphorus forms. Thus, it would be useful to find a model capable of estimating phosphorus concentration in different forms, whenever the present measurements are not possible.A multivariate progressive analysis of the measured phosphorus data set shows that total particulate phosphorus (TPP) concentration can be estimated as a function of two parameters, the percentage of a SS fraction coarser than 63 µm and the SRP concentration measured in filtered water. On the other hand, general statistical relationships exist between the various forms of phosphorus. Total soluble phosphorus (TSP) is dependent upon SRP. Organic phosphorus (OP) and non-apatite inorganic phosphorus (NAIP) can be approximately assessed from TPP, measured or calculated. Then, apatite phosphorus (AP), inorganic phosphorus (IP) and total phosphorus in raw water can be calculated by means of summation/substraction operations.Modelling is apparently suitable to the storm events during which only a limited volume of water samples could be collected. It also provides a rapid way to estimate the partitioning of phosphorus loads in high flow periods of the river system, thereby reducing the field and laboratory work required

Fractura diafisaria del antebrazo : tratamiento por fijación externa. Bases mecánico-anatómicas

Intentamos explicar en este trabajo las bases teórico-prácticas que seguimos en las fracturas diafisarias del antebrazo en su tratamiento mediante fijación externa según nuestros conocimientos anatómico-mecánicos.We try to explain in ihis paper the theoreticpractical basis that we follow in the dyaphiseal fractures of the forearm by skeletal fixation treatment according to our mechanical and anatomical knowledge