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

Biotic and abiotic factors affecting the Tasmanian distribution and density of the introduced New Zealand porcelain crab Petrolisthes elongatus

Petrolisthes elongatus (Milne-Edwards, 1837) was first introduced into southern Tasmania in the late 19th century putatively associated with live-oyster transfers from New Zealand. In the last century P. elongatus populations have expanded, inoculating rocky intertidal zones around Tasmania. We initially identified the scope of P. elongatus introduced range around Tasmania by visiting 57 sites to identify presence. Density of P. elongatus and populations of two native grapsid crab species was assessed at 12 sites around Tasmania to identify any biotic resistance. Abiotic factors including substrate availability and preference, and wave stress, were identified at each of the 57 sites. Our results indicate that P. elongatus has successfully invaded a large proportion of the southern and northern coasts of Tasmania, with a small number of sites on the east and none on the west coast supporting P. elongatus populations. Densities were found to be higher in southern Tasmania compared to the eastern and northern coastlines. Petrolisthes elongatus presence was found to be positively correlated with native grapsid crab presence, however, no statistically significant relationship was found between densities at scales of site or quadrat. Abiotic factors have been identified as the primary drivers of Petrolisthes distribution pattern

Marine biosecurity crisis decision-making: Two tools to Aid "Go"/"No Go" decision-making

Determining if a newly detected marine species is introduced to an area is an important first step when considering if control or eradication should be attempted. This step is often challenging, especially when data and introduced species expertise is limited: yet decisions about responding to a new invasion needs to occur in a timely manner. The crux is that biosecurity crisis decisions are often made in a vacuum. To improve this process, we consider expanded criteria to determine if a species is native, cryptogenic or introduced and outline application in a rapid response approach that uses a non-probabilistic decision tree to support decision makers. Effective use of the rapid response decision-tree and species criteria requires a multi-disciplinary approach drawing upon biology (taxonomy, phylogeny, genetics, ecology, biogeography) and monitoring. We assessed the expanded criteria against 213 bryozoan species present in Australian waters. A multivariate evaluation highlighted that a weight of evidence approach using the expanded criteria was successful in differentiating between native and introduced status. Our assessment highlighted that five criteria provide a high level of congruence with heuristic assignments, and provide a precautionary assignment of species\u27 status by reducing mis-classifications of introduced species as native species (Type I error) in comparison to the original criteria. However, differentiating between introduced and cryptogenic species remains problematic, especially when using the original criteria. We highlight the critical need for taxonomic identification, appropriate application of assigning cryptogenic status, and monitoring requirements to enable use of the criteria in a rapid response context. Using both the rapid response decision tree and the criteria provides a quantifiable mechanism to aid decision-makers in deciding whether to respond to a marine species introduction

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

Scaling properties of growing noninfinitesimal perturbations in space-time chaos

We study the spatiotemporal dynamics of random spatially distributed noninfinitesimal perturbations in one-dimensional chaotic extended systems. We find that an initial perturbation of finite size $\epsilon_0$ grows in time obeying the tangent space dynamic equations (Lyapunov vectors) up to a characteristic time $t_{\times}(\epsilon_0) \sim b - (1/\lambda_{max}) \ln (\epsilon_0)$, where $\lambda_{max}$ is the largest Lyapunov exponent and $b$ is a constant. For times $t < t_{\times}$ perturbations exhibit spatial correlations up to a typical distance $\xi \sim t^z$. For times larger than $t_{\times}$ finite perturbations are no longer described by tangent space equations, memory of spatial correlations is progressively destroyed and perturbations become spatiotemporal white noise. We are able to explain these results by mapping the problem to the Kardar-Parisi-Zhang universality class of surface growth.Comment: 4.5 pages LaTeX (RevTeX4) format, 3 eps figs included. Submitted to Phys Rev

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