Time decay of scaling invariant Schroedinger equations on the plane

We prove the sharp L^1-L^{\infty} time-decay estimate for the 2D-Schroedinger equation with a general family of scaling critical electromagnetic potentials.Comment: 26 page

Estimating the Impact of State Policies and Institutions with Mixed-Level Data

Researchers often seek to understand the effects of state policies or institutions on individual behavior or other outcomes in sub-state-level observational units (e.g., election results in state legislative districts). However, standard estimation methods applied to such models do not properly account for the clustering of observations within states and may lead researchers to overstate the statistical significance of state-level factors. We discuss the theory behind two approaches to dealing with clusteringclustered standard errors and multilevel modeling. We then demonstrate the relevance of this topic by replicating a recent study of the effects of state post-registration laws on voter turnout (Wolfinger, Highton, and Mullin 2005). While we view clustered standard errors as a more straightforward, feasible approach, especially when working with large datasets or many cross-level interactions, our purpose in this Practical Researcher piece is to draw attention to the issue of clustering in state and local politics research.mixed-level data, voter turnout

Estimating the Impact of State Policies and Institutions with Mixed-Level Data

Researchers often seek to understand the effects of state policies or institutions on individual behavior or other outcomes in sub-state-level observational units (e.g., election results in state legislative districts). However, standard estimation methods applied to such models do not properly account for the clustering of observations within states and may lead researchers to overstate the statistical significance of state-level factors. We discuss the theory behind two approaches to dealing with clustering—clustered standard errors and multilevel modeling. We then demonstrate the relevance of this topic by replicating a recent study of the effects of state post-registration laws on voter turnout (Wolfinger, Highton, and Mullin 2005). While we view clustered standard errors as a more straightforward, feasible approach, especially when working with large datasets or many cross-level interactions, our purpose in this Practical Researcher piece is to draw attention to the issue of clustering in state and local politics research

Preliminary Observations on the Ability to Adapt To Salinity Changes in Nursehound Scyliorhinus Stellaris (Linnaeus, 1758) and Small Spotted Catsharks Scyliorhinus Canicula

Nursehound Scyliorhinus stellaris and small spotted catsharks Scyliorhinus canicula are frequently hosted in public aquaria and their husbandry is improving. The reproduction of this species in captive conditions is not difficult and juveniles are easily maintained in laboratory or in thematic tanks showed to the public. Data on juveniles are easily acquired in order to understand different aspects of their natural life and physiology. In two stages, during 2006 and 2010, six S. stellaris and three S. canicula juveniles were tested at different salinity levels under controlled conditions in order to understand their responses in terms of respiration rate to this stress. In fact this is a benthic species living at constant water quality parameters at approximately 70-100 meters deep

Antioxidant activity of isolated compounds in non-volatile residue from orange essential oil

6 páginas, 3 figuras.[ES] Existe un creciente interés en la industria alimentaria y en la medicina preventiva por la búsqueda de «antioxidantes naturales», por lo que nos planteamos evaluar la actividad antioxidante del residuo no volátil del aceite esencial de naranja contra la oxidación del aceite de oliva sin retinar y de reciente extracción. Mediante destilación del aceite esencial de naranja se obtuvo el residuo no-volátil, el cual se fraccionó en columna de silica gel 60. La actividad antioxidante fue medida por el valor de peróxidos producidos por el aceite de oliva al provocar la oxidación por calentamiento a 70 °C durante 48 h. Se aislaron seis compuestos mediante H PLC preparativo de los cuales cuatro tuvieron actividad antioxidante. Usando métodos espectroscópicos se identificaron a-tocoferol y tres flavonas metoxiladas. Con este estudio se confirmó que la fracción no volátil del aceite esencial de naranja contiene antioxidantes naturales diferentes al a-tocoferol.[EN] There has been a growing interest in the food industry and in preventive medicine to search for «natural antioxidants». Therefore the objetive of this study was to evaluate the antioxidant activity of the non-volatile residue of essential orange oil in the oxidation of unrefined and freshly extracted olive oil. Essential orange oil was distilled to obtain a non-volatile residue and fracctionated on a Silica Gel 60 column. The antioxidant activity was determined by measuring peroxide value obtained after heating olive oil at 70 °C for 48 h. Six compounds were isolated and purified, four of these had antioxidant activity, a-tocopherol and three methoxylated flavones were identified using spectroscopic methods. This study confirmed that non-volatile fractions of essential orange oil contain natural antioxidants diferent from a-tocopherol.Peer reviewe