A multi-family GLRT for detection in polarimetric SAR images

This paper deals with detection from multipolarization SAR images. The problem is cast in terms of a composite hypothesis test aimed at discriminating between the Polarimetric Covariance Matrix (PCM) equality (absence of target in the tested region) and the situation where the region under test exhibits a PCM with at least an ordered eigenvalue smaller than that of a reference covariance. This last setup reflects the physical condition where the back scattering associated with the target leads to a signal, in some eigen-directions, weaker than the one gathered from a reference area where it is apriori known the absence of targets. A Multi-family Generalized Likelihood Ratio Test (MGLRT) approach is pursued to come up with an adaptive detector ensuring the Constant False Alarm Rate (CFAR) property. At the analysis stage, the behaviour of the new architecture is investigated in comparison with a benchmark (but non-implementable) and some other adaptive sub-optimum detectors available in open literature. The study, conducted in the presence of both simulated and real data, confirms the practical effectiveness of the new approach

The role of path choice and traffic assignment models in evacuation

n/

Application of SINTACS method to the aquifers of Piana di Palermo, Siciliy,Italy

Piana di Palermo is characterized by the presence of two different aquifers: one shallow, constituted by calcarenites and the other deep in fractured carbonates. The calcarenitic aquifer presents a low potential compared to the carbonatic aquifer. The chemistry of the water in both aquifers reflects water-rock interaction, seawater intrusion, ionic exchange etc. The application of SINTACS method showed that about 80% of the study area can be classified as of high to very high vulnerability.Piana di Palermo es caracterizada por la presencia de dos acuíferos diferentes: uno somero constituido por calcarenitas y otro profundo en rocas carbonatadas fracturadas. El acuífero calcarenítico presenta un bajo potencial hídrico comparado con el acuífero carbonático. El comportamiento químico del agua en ambos acuíferos refleja severos procesos como interacción agua-roca, intrusión marina, cambio iónico, etc. La aplicación del método SINTACS mostró que cerca del 80 % del área en estudio puede ser clasificada como de alta a muy alta vulnerabilidad

Fostering savings by commitment: Evidence from a quasi-natural experiment at The Small Enterprise Foundation in South Africa

We studied the effects of a pilot project that strengthened savings incentive mechanisms. The project was established by The Small Enterprise Foundation (SEF), a leading microfinance institution based in South Africa. The program introduced a savings stimulus in the form of a Goal Card: clients subscribing to this (non-coercive) tool were required to identify a savings goal and to commit to regular payments to reach it. The experiment had a quasi-natural approach as it was implemented by SEF in non-randomly selected locations. Difference-in-differences estimates show improved savings habits among those of the foundation's customers who were involved in the program, compared to the counterfactual that are identified using propensity score matching. The effect of the program manifested in its second semester, suggesting a persistent change of habits but a slow accumulation of savings. We conclude that asking microcredit customers to identify a savings goal and commit to a regular savings amount to achieve it is a promising savings incentive mechanism

Photo-Protective Mechanisms and the Role of Poly (ADP-Ribose) Polymerase Activity in a Facultative CAM Plant Exposed to Long-Term Water Deprivation

The Crassulacean acid metabolism (CAM) pathway helps plants to alleviate the oxidative stress under drought, but the shift to CAM-idling may expose plants to the overproduction of reactive oxygen species causing cell damages. The facultative CAM species Portulacaria afra L., was subjected to long-term water deprivation to assess the photo-protective strategies and the poly (ADP-ribose) polymerase (PARP) activity during water stress and plant capability to recover from the stress. Measurements of titratable acidity, chlorophyll fluorescence emission, and antioxidant activity were performed during the stress and rewatering. Under water deprivation, plants shifted from C3 to CAM metabolism, reaching the CAM-idling status at the end of the stress period. The daily variation of the titratable acidity and PARP activity increased at the beginning of stress and declined with stress progression, reaching the lowest value at the end of stress treatment. H2 O2 content, superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities increased with the severity of water stress. The photochemical processes remained high during the entire stress period indicating the presence of alternative sinks to CO2 fixation. The elevated activity of catalase under severe water stress suggests the occurrence of photorespiration in sustaining the photosynthetic electron transport under CAM-idling condition. The overall data indicate that scavenger enzymes, photorespiration and PARP activity modulation contribute to the strong resistance of P. afra to severe water stress, preserving the functioning of photosynthetic apparatus and ensuring plant recovery with rewatering

The Work of Roberto Busa SJ: Open Spaces between Computation and Hermeneutics

A review of the achievements of Fr. Busa over the course of his 60 years of work in the area of computational linguistics: internal hypertexts, the systematization of allographs, lemmatization, homographs and typologies; the lexical system; the laws of economy for graphemes, for semantic typology, for heterogeneity among terms, and of the two lexical hemispheres. Finally, the project of disciplined languages is mentioned, a response to the linguistic challenge resulting from informational globalization

Recurrent Nevus. A 5-Year Review

A persistência de uma lesão melanocítica, em local onde tenha sido previamente excisado um nevo melanocítico pode colocar, clínica e histologicamente, problemas no diagnóstico diferencial com melanoma, designado por alguns autores como ‘pseudomelanoma’. Neste estudo, os autores pretendem realizar uma análise comparativa entre os achados clínicos e histopatológicos das lesões melanocíticas primárias e dos nevos recorrentes. Procura-se também avaliar eventuais factores predisponentes para este fenómeno

The interplay between chemical and mechanical feedback from the first generation of stars

We study cosmological simulations of early structure formation, including non-equilibrium molecular chemistry, metal pollution from stellar evolution, transition from population III (popIII) to population II (popII) star formation, regulated by a given critical metallicity, and feedback effects. We investigate the properties of early metal spreading from the different stellar populations and its interplay with primordial molecular gas. We find that, independently of the details about popIII modeling, after the onset of star formation, regions enriched below the critical level are mostly found in isolated environments, while popII star formation regions are much more clumped. Typical star forming haloes show average SN driven outflow rates of up to 10^{-4} Msun/yr in enriched gas, initially leaving the original star formation regions almost devoid of metals. The polluted material, which is gravitationally incorporated in over-dense environments on timescales of 10^7 yr, is mostly coming from external, nearby star forming sites ("gravitational enrichment"). In parallel, the pristine-gas inflow rates are between 10^{-3} - 10^{-1} Msun/yr. However, thermal feedback from SN generates turbulence and destroys molecules within the pristine gas, and only the polluted material, incorporated via gravitational enrichment, can continue to cool by atomic metal fine-structure transitions on time scales short enough to end the initial popIII regime within less than 10^8 yr.Comment: Accepted on the 31/1/201