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

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

Desarrollo y aplicaciones de un modelo de crecimiento para plantaciones de Pinus radiata D. Don en El Bierzo (León)

A dynamic growth model for Pinus radiata D. Don plantations in El Bierzo (Spain) was developed with data from two inventories of permanent plots, of between 7 and 36 years old, established by the University of León. In this model, stand conditions at any point in time are defined by three state variables (stand basal area, number of trees per hectare and dominant height).Themodel includes three transition functions derived by the generalized algebraic difference approach to enable projection of the state variables at any particular time. Once they are known, the number of trees in each diameter class is estimated with a distribution function, by recovery of the parameters of theWeibull function by use of the moments method. Finally, a generalized height-diameter function and a taper function allow estimation of total or merchantable stand volume. The model provides satisfactory predictions for a time interval of three years. Simulation of the growth of four stands under two silvicultural regimes and two different sites confirm that the estimates provided by the overall model adequately represent the effects of both stand density and site quality. Other applications for the model are analysed and discussed.Se ha desarrollado un modelo dinámico de crecimiento para plantaciones de Pinus radiata D. Don en El Bierzo (León) a partir de datos de dos inventarios de parcelas permanentes, de entre 7 y 36 años de edad, establecidas por la Universidad de León. En este modelo, las condiciones del rodal en un instante dado están definidas por tres variables de estado (área basimétrica, número de pies por hectárea y altura dominante). El modelo incluye tres funciones de transición obtenidas mediante la metodología de ecuaciones en diferencias algebraicas generalizadas que permite la proyección de las variables de estado a un determinado instante en el tiempo. Una vez conocidas las variables de estado, una función de distribución estima el número de pies en cada clase diamétrica mediante la metodología de recuperación de los parámetros de la función deWeibull usando el método de los momentos. Finalmente, una función de altura-diámetro generalizada y una función de perfil de tronco permiten la estimación del volumen total o comercial del rodal. El modelo proporciona predicciones satisfactorias para un intervalo de proyección de tres años. La simulación del crecimiento de cuatro rodales bajo dos regímenes selvícolas distintos y dos calidades de estación diferentes corrobora que las estimaciones proporcionadas por el modelo global representan adecuadamente los efectos de la densidad de la masa y la calidad de la estación. Finalmente se analizan y discuten otras aplicaciones del modelo elaborado

Influence of Recycled Precast Concrete Aggregate on Durability of Concrete's Physical Processes

ABSTRACT: The research presented in this article analysed the influence of incorporating precast concrete waste as an alternative to coarse aggregate in self-compacting concrete to generate new precast elements. The experimental study involved the characterization of recycled aggregate and the design of the mix of the new self-compacting concrete (SCC). The experimental study evaluates the physical processes that affect the durability of concrete with percentages of incorporation such as 20%, 50% and 100% of recycled aggregate. Two types of SCC were manufactured with minimum compressive strength of 30 MPa and 45 MPa. The properties analysed were density of hardened SCC, shrinkage cracking, freeze-thaw resistance, resistance to ageing by thermal shock and abrasion resistance. The results obtained were compared with those of the control concrete, observing great capacity of the SCC under physical aggressions that affect durability. The results of this research show that it is possible to use the recycled aggregate coming from precast pieces in order to the manufacture of self-compacting recycled concrete in the same precast industry. However, high loss of proprieties occurs for a 100% substitution, while for 20% and 50%, the variations with respect to control concrete are smaller. In addition, taking advantage of this waste to incorporate it back into the production chain contributes to more sustainable construction.This research was funded by Junta de Castilla y León (Regional Government) for funding UIC-231 through project BU119P17; MINECO for funding through project BIA2014-55576-C2-1-R; FEDER (European Regional Development Funds) and LADICI

Kidney biopsy in Lupus Nephritis: still essential in clinical practice

Renal involvement in Systemic Lupus Erythematous is common and its management remains a daily challenge for clinical providers. Percutaneous kidney biopsy remains the gold standard for diagnosis of lupus nephritis. More recently, we have seen the role of the biopsy being challenged, considering the widespread use of corticosteroids and mycophenolate mofetil for all forms of lupus nephritis. We present a review of published evidence regarding first and repeat kidney biopsies for patients with lupus nephritis. Based on the available literature, we recommend a kidney biopsy to guide treatment and determine prognosis and we also suggest an algorithm for kidney rebiopsy in lupus nephritis.info:eu-repo/semantics/publishedVersio

European marine aggregates resources: Origins, usage, prospecting and dredging techniques

Marine aggregates (sand and gravel) are important mineral resources and traded commodities. Their significance is bound to increase further, due to increasing coastal zone development, stricter environmental regulation concerning land-won aggregates and increasing demand for beach replenishment material. Marine aggregate (MA) deposits can be differentiated into relict and modern deposits. The former consist of sedimentary material deposited in the past and under different environmental and sedimentary regimes than those existing presently (e.g. the gravel/ sand deposits of the Pleistocene buried river valleys of the northwestern European shelves). The latter are deposits, which have been formed and controlled by the modern hydro-and sediment dynamic conditions (e.g. the linear sand banks of the southern North Sea). The present contribution reviews the current state of affairs in 9 representative European Member States concerning the prospecting and extraction (dredging) techniques as well as the levels of production and usage. The review has shown a mixed record as, in some of the studied States, marine aggregate production is an important and streamlined activity, whereas other States have not yet developed efficient marine aggregate policies and industries. It has also shown that although attempts have been lately made to coordinate the field, the industry still faces problems, which hinder its sustainable development. These include (amongst others): lack of standardisation of the relevant information, difficulties in the access to information, non-coherent regulatory regimes and limited collaboration/coordination between the marine scientific research establishments and the marine aggregate industry. These issues should be addressed as quickly as possible in order to exploit effectively this important mineral resource