Gauge Consistent Wilson Renormalization Group I: Abelian Case

A version of the Wilson Renormalization Group Equation consistent with gauge symmetry is presented. A perturbative renormalizability proof is established. A wilsonian derivation of the Callan-Symanzik equation is given.Comment: Latex2e, 39 pages, 3 eps figures. Revised version to appear in Int. J. Mod. Phy

Local seismic response studies in the north-western portion of the August 24th, 2016 Mw 6.0 earthquake affected area. The case of Visso village (Central Apennines).

In this work, we investigate the possible causes of the differential damaging observed in Visso village (Central Apennines, about 28 km north from the August 24th, 2016 Mw 6.0 earthquake epicenter). Following insights from the available geological cartography at 1:10.000 scale, a preliminary geophysical survey has been performed in the damaged area in order to constrain geometries and extent of the subsoil lithotypes. Then, these results have been used to retrieve a Vs profile close to the most heavily damaged buildings. This latter has been used as input for a numerical analysis aimed at deriving the motion at the ground level in the study area. In particular, a linear equivalent simulation has been performed by means of EERA code and the waveform has been obtained convolving the time history recorded during the August 24th, 2016 mainshock at Spoleto Monteluco (SPM) site. Our preliminary results indicate a possible correlation of damaging to the thickness and shape of the geological units. Nevertheless, further analyses are necessary to highlight any 2D basin and / non- linear soil behaviour effects in order to compare them to the intrinsic buildings vulnerability, according to the EMS98 guidelines

Artificial neural networks for 3D cell shape recognition from confocal images

We present a dual-stage neural network architecture for analyzing fine shape details from microscopy recordings in 3D. The system, tested on red blood cells, uses training data from both healthy donors and patients with a congenital blood disease. Characteristic shape features are revealed from the spherical harmonics spectrum of each cell and are automatically processed to create a reproducible and unbiased shape recognition and classification for diagnostic and theragnostic use.Comment: 17 pages, 8 figure

Enantioselective Biocascade Catalysis with a Single Multifunctional Enzyme

Asymmetric catalytic cascade processes offer direct access to complex chiral molecules from simple substrates and in a single step. In biocatalysis, cascades are generally designed by combining multiple enzymes, each catalyzing individual steps of a sequence. Herein, we report a different strategy for biocascades based on a single multifunctional enzyme that can promote multiple stereoselective steps of a domino process by mastering distinct catalytic mechanisms of substrate activation in a sequential way. Specifically, we have used an engineered 4-oxalocrotonate tautomerase (4-OT) enzyme with the ability to form both enamines and iminium ions and combine their mechanisms of catalysis in a complex sequence. This approach allowed us to activate aldehydes and enals toward the synthesis of enantiopure cyclohexene carbaldehydes. The multifunctional 4-OT enzymes could promote both a two-component reaction and a triple cascade characterized by different mechanisms and activation sequences

Regional Seismic Characterization of Shallow Subsoil of Northern Apulia (Southern Italy)

A first-order seismic characterization of Northern Apulia (Southern Italy) has been provided by considering geological information and outcomes of a low-cost geophysical survey. In particular, 403 single-station ambient vibration measurements (HVSR techniques) distributed within the main settlements of the area have been considered to extract representative patterns deduced by Principal Component Analysis. The joint interpretation of these pieces of information allows the identification of three main domains (Gargano Promontory, Bradanic Through and Southern Apennines Fold and Thrust Belt), each characterized by specific seismic resonance phenomena. In particular, the Bradanic Through is homogeneously characterized by low frequency (< 1 Hz) resonance effects associated with relatively deep (> 100 m) seismic impedance, which is contrasting corresponding to the buried Apulian carbonate platform and/or sandy horizons located within the Plio-Pleistocene deposits. In the remaining ones, relatively high frequency (> 1 Hz) resonance phenomena are ubiquitous due to the presence of shallower impedance contrasts (< 100 m), which do not always correspond to the top of the geological bedrock. These general indications may be useful for a preliminary regional characterization of seismic response in the study area, which can be helpful for an effective planning of more detailed studies targeted to engineering purposes

Atmospheric forcing as a source for ocean variability at the brazil-malvinas confluence zone

The goal of this study is to evalúate the impact of the atmospheric forcing of the scale of the storms on the oceanic circulation and temperature at the Brazil-Malvinas Confluence Zone. SST data and numerical simulations are used to get some insight on the mechanisms responsible for the establishment of the oceanic temperature and velocity fields response to the wind variability and to analyze the penetration depth, the time and the persistence of this response. Results show that atmospheric storms can be very effective on generating a SST persistent perturbation in the area and given their high frequency they can generate an important effect on the variability of the SST and its mean. Two possible mechanisms are considered for the oceanic response, the wind stress forcing and the heat exchange through the ocean-atmosphere interface. The latter probes to be the most important one. Even though the wind stress forcing has a rol on modifying the oceanic characteristics by means of advection, it is a slow process that will only be effective if the atmospheric perturbation remains for long periods. In contrast, the heat flux through the ocean surface is much more rapid and effective, particularly in cooling the ocean. The cooling of the ocean surface produces static instability and convection that rapidly transfers the cooling to lower layers. Vertical mixing relatively heats the ocean surface allowing for a new cooling by means of interaction with the atmosphere. Results show that even though most of the energy is lost as inertia-gravity waves, it takes to the ocean 24 hours to develop a geostrophically balanced response and it is proportional to the persistence of the atmospheric event. Once the response is setup into the ocean, it tends to remain even though the atmospheric disturbance disappears, because oceanic dissipative effects are of a much longer temporal scale than the atmospheric ones. The scale of penetration results to be of the order of 200 meters. Therefore, in a broad and shallow región such as the Argentinean continental shelf these events might be able to produce the mixing of the whole water column. Atmospheric storms in the area have a mean annual frequency higher than once a week and the signal is present in the ocean for a longer period. The results suggest that atmospheric variability on the scale of the storms can be very important on determining the local SST.El objetivo de este trabajo es evaluar el impacto del forzante atmosférico en la escala de las tormentas sobre la circulación y la temperatura del océano en la región de la Confluencia Brasil-Malvinas. Se utilizan datos de temperatura de la superficie del mar (TSM) y simulaciones numéricas con el objetivo de estudiar los mecanismos responsables del establecimiento de la respuesta de los campos de temperatura y velocidad en el océano a la perturbación atmosférica y analizar la profundidad de penetración, el tiempo y la persistencia de esta respuesta. Los resultados indican que las tormentas atmosféricas pueden ser muy efectivas en la generación de una perturbación persistente de la TSM en el área y, dada su alta frecuencia, pueden tener un efecto importante en la variabilidad de la TSM y su media. Se consideran dos mecanismos posibles en la generación de la respuesta, el forzante del viento y el intercambio de calor a través de la interfase mar-atmósfera. El último resulta ser el más importante. Aunque el esfuerzo del viento modifica el océano por advección, éste es un proceso muy lento, que sólo puede ser efectivo si la perturbación atmosférica permanece por períodos largos. En contraste, el flujo de calor a través de la superficie del mar es un mecanismo mucho más rápido y efectivo, especialmente enfriando el océano. Un enfriamiento de la superficie del mar produce inestabilidad estática y convección, que rápidamente transfiere el enfriamiento a capas más profundas. La mezcla vertical a su vez calienta relativamente la superficie del océano, facilitando un nuevo enfriamiento por interacción mar-atmósfera. Los resultados muestran que, aunque gran parte de la energía se pierde como ondas grávito-inerciales, en 24 horas el océano desarrolla una respuesta balanceada geostróficamente y que esta respuesta es proporcional a la persistencia del evento atmosférico. Una vez que la respuesta oceánica se establece, tiende a permanecer aunque la perturbación atmosférica desaparezca, porque los efectos disipativos tienen una escala temporal mucho más larga en el océano que en la atmósfera. La escala de penetración resulta ser del orden de 200 metros. Por lo tanto, en una región ancha y somera como la Plataforma Continental Argentina, estos eventos podrían producir la mezcla de toda la columna de agua. Las tormentas atmosféricas en el área tienen una frecuencia anual mayor a un evento semanal y la señal permanece en el océano durante un tiempo aún más largo. Los resultados sugieren que la variabilidad atmosférica en la escala de las tormentas puede tener un gran impacto en la TSM local.Asociación Argentina de Geofísicos y Geodesta

Un modelo analítico para la variación transversal de la circulación en estuarios asociada a cambios en la batimetría

El objetivo de este trabajo es evaluar la variación transversal del flujo en estuarios asociada a cambios en la batimetría por medio del análisis de modelos conceptuales bidimensionales en los que se considera la respuesta de las corrientes a la acción de diversos forzantes externos. Estos se aplicaron sobre dos tipos de secciones transversales de estuarios diferentes: uno con una sección rectangular y otro con una sección característica del estuario de Bahía Blanca, con una planicie de marea. Se analizó la respuesta de estos estuarios bajo la acción de los forzantes más importantes: la estructura de densidad, la acción de un viento local y finalmente un forzante remoto. Los modelos conceptuales presentados indican que los mecanismos de forzante analizados producen una circulación que es fuertemente dependiente de la batimetría. Para estuarios con estructura batimétrica transversal no uniforme, la respuesta a los forzantes tampoco es uniforme en esta dirección. Sin embargo, para una configuración batimétrica dada, las soluciones pueden ser normalizadas independizándolas de la intensidad del forzante. Por lo tanto, para una configuración batimétrica dada, una vez integrada la ecuación sólo es necesario un dato de velocidad a una cierta profundidad para hacer una estimación razonable de las corrientes en todos los niveles. Cuando los mecanismos de forzante actúan combinados, pueden reforzarse o contrarrestarse mutuamente. Nuestro análisis indica que las variaciones en la batimetría a través del estuario y son muy importantes para la creación de variaciones transversales en el patrón de corrientes. Sin embargo, este tipo de variaciones podría ser difícil de detectar en la naturaleza debido a la superposición de efectos. Estas variaciones laterales de la velocidad podrían tener importantes implicancias en el mantenimiento del transporte residual y el balance de salinidad dentro del estuario.The aim of this paper is to evalúate the lateral variations of the flow in estuaries related to changes in the bathymetry, by means of the analysis of conceptual bidimensional models in which the response to the currents to different external forcings is considered. These models are applied to two kind of estuaries: one with a rectangular bathymetry section and the other one with a section that is characteristic of the estuary of Bahía Blanca, including a tidal fíat. The response to the most important forcings is analyzed. These forcings are the density structure, the action of a local wind and a remote forcing. The analytical models indícate that the analyzed forcings produce a circulation that strongly depends upon the topography. For estuaries with a non-uniform transversal topographic structure, the response is non-uniform in that direction as well. Nevertheless, for a given bathymetry, the solutions can be normalized and made independent of the intensity of the forcing. Therefore, once the equation has been integrated for a given bathymetry, only one velocity data at some depth is needed to make a reasonable estimation of the currents at any level. When the different forcings act together they can either reinforce or debilítate each other. Our analysis indicates that the topography variations across the estuaries are very important in the creation of transversal variations of the current pattern. Nevertheless, due to the superposition effects, it might be difficult to observe this kind of variations in nature. These velocity variations might have important implications in the maintenance of the residual transport and salinity balance in the estuaries.Asociación Argentina de Geofísicos y Geodesta

Beta function and infrared renormalons in the exact Wilson renormalization group in Yang-Mills theory

We discuss the relation between the Gell-Mann-Low beta function and the ``flowing couplings'' of the Wilsonian action S_\L[\phi] of the exact renormalization group (RG) at the scale \L. This relation involves the ultraviolet region of \L so that the condition of renormalizability is equivalent to the Callan-Symanzik equation. As an illustration, by using the exact RG formulation, we compute the beta function in Yang-Mills theory to one loop (and to two loops for the scalar case). We also study the infrared (IR) renormalons. This formulation is particularly suited for this study since: $i$) \L plays the r\^ole of a IR cutoff in Feynman diagrams and non-perturbative effects could be generated as soon as \L becomes small; $ii$) by a systematical resummation of higher order corrections the Wilsonian flowing couplings enter directly into the Feynman diagrams with a scale given by the internal loop momenta; $iii$) these couplings tend to the running coupling at high frequency, they differ at low frequency and remain finite all the way down to zero frequency.Comment: 19 pages, 6 figures, LaTex, uses epsfig, rotatin