A search for magnetic fields on central stars in planetary nebulae

One of the possible mechanisms responsible for the panoply of shapes in planetary nebulae is the presence of magnetic fields that drive the ejection of ionized material during the proto-planetary nebula phase. Therefore, detecting magnetic fields in such objects is of key importance for understanding their dynamics. Still, magnetic fields have not been detected using polarimetry in the central stars of planetary nebulae. Circularly polarized light spectra have been obtained with the Focal Reducer and Low Dispersion Spectrograph at the Very Large Telescope of the European Southern Observatory and the Intermediate dispersion Spectrograph and Imaging System at the William Herschel Telescope. Nineteen planetary nebulae spanning very different morphology and evolutionary stages have been selected. Most of central stars have been observed at different rotation phases to point out evidence of magnetic variability. In this paper, we present the result of two observational campaigns aimed to detect and measure the magnetic field in the central stars of planetary nebulae on the basis of low resolution spectropolarimetry. In the limit of the adopted method, we can state that large scale fields of kG order are not hosted on the central star of planetary nebulae.Comment: Paper accepted to be published in Astronomy and Astrophysics on 20/01/201

Upper limits to the magnetic field in central stars of planetary nebulae

More than about twenty central stars of planetary nebulae (CSPN) have been observed spectropolarimetrically, yet no clear, unambiguous signal of the presence of a magnetic field in these objects has been found. We perform a statistical (Bayesian) analysis of all the available spectropolarimetric observations of CSPN to constrain the magnetic fields on these objects. Assuming that the stellar field is dipolar and that the dipole axis of the objects are oriented randomly (isotropically), we find that the dipole magnetic field strength is smaller than 400 G with 95% probability using all available observations. The analysis introduced allows integration of future observations to further constrain the parameters of the distribution, and it is general, so that it can be easily applied to other classes of magnetic objects. We propose several ways to improve the upper limits found here.Comment: 7 pages, 3 figures, accepted for publication in Ap

Cellular Variant of Focal Segmental Glomerulosclerosis Treated with Plasma Exchange

Focal segmental glomerulosclerosis (FSGS) is the most common primary glomerular disease in nephrotic patients in the United States, frequently leading to end stage renal disease (ESRD). The cellular variant is a rare form of FSGS commonly associated with poor outcome. We report a case of cellular variant FSGS with progressive kidney dysfunction successfully treated with plasma exchange (PE). A 49-year-old Caucasian female presented with two days of ankle edema and hypertension. Laboratory findings showed serum creatinine (SCr) 1.6 mg/dL, urine albumin/creatinine ratio (uACR) 2.8 g/g, haematuria 3+ and no immunological abnormalities. Kidney biopsy revealed a cellular FSGS variant with segmental endocapillary proliferation on light microscopic, negative immunofluorescence and widespread foot process effacement by electronic microscopic. Prednisolone 1 mg/Kg was started. Four days later the SCr worsened (3.6 mg/dL) and the patient became severely nephrotic with uACR of6.8g/g, quickly attaining a maximum of 24.6 g/g in a short time and albumin of 2.15g/dL. Pulsed methyl prednisolone was started. Despite a 10 course of steroids, no clinical improvement was observed. Considering the rapidly worsening renal function and severe nephrotic syndrome, PE was begun in association with mycophenolate mofetil and tacrolimus. Kidney function recovered after one week. Complete remission was achieved at 3rd week and remains in complete remission at 27 months follow-up. Prolonged remission is a challenge in primary FSGS. PE associated with combined immunosuppression was effective in the present case. The short and long-term effects of plasma exchange in primary FSGS should be evaluated in prospective studies.info:eu-repo/semantics/publishedVersio

Letter to the editor: Measles outbreak linked to an international dog show in Slovenia - primary cases and chains of transmission identified in Italy, November to December 2014

In the letter epidemiological and virological investigations on Italian measles cases associated to a measles outbreak in Slovenia, linked to an international dog show from 8 to 9 November 2014, are described

Reflectometry measurements of the m=1 satellite mode in L- and H-mode plamas in ASDEX

In ASDEX, with strong NB, heating, often a large central m=1, n=1 mode is observed on the SXR emission. For PNBI > 1 MW a mode rotating with the same frequency, the so-called`m=1 satellite`, is seen on the magnetic pick-up coils in the L and H-phases. Magnetic measurement s in the divertor chamber suggest that the satellite mode might be located outside the separatix, on open field lines reaching the diretor /1/. Here we present results from localized microave reflectrometric measurements. The time evolution of the satellite mode frequency is studied for plasmas with different qa and the mode localization is estimated, confirming that is shoud be close to but outside the separatrix. The central toroidal rotation velocities of the plasma can be inferred from the measured frenquencies of the satellite modes

Changes in the density profile due to the m=2 tearing mode in asdex

Resistive MHO tearing modes can develop magnetic islands near the rational magnetic surfaces, where q=m/ n

Recent results of H-mode studies on asdex

In a comparative study of various confinement regimes the H-mode demonstrated the best performance. Confinement enhancement factors (above ITER 89-P L-mode scaling) in the range of 1.6 fH 2.8 have been achieved with values depending on the divertor configuration, the wall condition, ELM behaviour and the plasma ion spicies. Long-pulse H-phases, withELMs, of up to 3.5s with constant confinement time, recycling and impurity characteristics are archived. H* -mode operation is possible without a loss of current scaling at qa values as low as 2.2. The B-limit is the same with and without ELMs. Murakami parameters are similar in H-and L-modes

Multiscale magnetic underdense regions on the solar surface: Granular and Mesogranular scales

The Sun is a non-equilibrium dissipative system subjected to an energy flow which originates in its core. Convective overshooting motions create temperature and velocity structures which show a temporal and spatial evolution. As a result, photospheric structures are generally considered to be the direct manifestation of convective plasma motions. The plasma flows on the photosphere govern the motion of single magnetic elements. These elements are arranged in typical patterns which are observed as a variety of multiscale magnetic patterns. High resolution magnetograms of quiet solar surface revealed the presence of magnetic underdense regions in the solar photosphere, commonly called voids, which may be considered a signature of the underlying convective structure. The analysis of such patterns paves the way for the investigation of all turbulent convective scales from granular to global. In order to address the question of magnetic structures driven by turbulent convection at granular and mesogranular scales we used a "voids" detection method. The computed voids distribution shows an exponential behavior at scales between 2 and 10 Mm and the absence of features at 5-10 Mm mesogranular scales. The absence of preferred scales of organization in the 2-10 Mm range supports the multiscale nature of flows on the solar surface and the absence of a mesogranular convective scale

Recursos minerales marinos en las rías gallegas y en la plataforma continental adyacente.

La riqueza natural de las rías gallegas y de su plataforma adyacente no se restringe exclusivamente a las pesquerías. Los recursos minerales marinos, entre los que se encuentran los áridos, placeres, sal marina, fosforitas, hidrocarburos e hidratos de gas poseen un interés económico intrínseco muy importante. Aunque las explotaciones de sal marina tuvieron importancia histórica en Galicia, en la actualidad el aprovechamiento económico de los recursos minerales marinos se limita a los áridos empleados en la regeneración de playas. Una compleja interacción de factores jurídicos, tecnológicos y económicos ha inhibido hasta ahora el desarrollo de otros recursos. Sin embargo, el nuevo orden político y económico internacional proporciona un escenario muy distinto que facilita su explotación. Sensibles a este cambio, las instituciones responsables han impulsado el desarrollo de programas de evaluación de algunos de estos recursos, cuyos resultados se exponen aquí. Este es el caso de los hidrocarburos, de interés energético estratégico, o de los placeres cuyo interés se basa en la presencia de ciertos metales y tierras raras empleados en los nuevos materiales. En este sentido es deseable que en los próximos años se considere también la evaluación de recursos energéticos alternativos como los hidratos de gas, o de otros que como las fosforitas, poseen un interés estratégico especial para la creciente demanda de fertilizantes que anticipa la racionalización del sector agropecuario en la región. Sólo una completa evaluación del potencial económico de 67 G. Méndez et al. Recursos minerales marinos en las rías gallegas... todos los recursos minerales marinos en Galicia permitirá planificar una política de desarrollo sostenido adecuada.The natural wealth of the Galician rias and adjoining platform is not constrained to their well know fisheries. Their marine mineral resources, such as aggregates, placers, marine salt, phosphorites, hydrocarbons and gas hydrates, also have very significant intrinsic economic value. Despite a number of marine salt exploitations of historical relevance, the economic importance of marine mineral mining in Galicia, at present day, is limited to aggregates for beach renourishment. A complex interaction of legal, technological and economical factors has inhibited the development of other resources. However, the new international political and economical order has provided a very different scenario that favours their exploitation. Sensitive to this change, the relevant institutions have put in place evaluation programs for some of these resources, whose results will be shown here. This is the case of hydrocarbons, of strategic energy interest, or placers a source of metals and rare-earth elements for the new materials industry. In this sense it is desirable that alternative energy resources like gas hydrates, or strategically interesting resources for agriculture like phosphorites will be adequately evaluated in the next few years. Only a complete evaluation of the true economical importance of all the marine mineral resources in Galicia will allow adequate long-term planning of successful sustained development policies