Conjugate two-dimensional electric potential maps

Two dimensional electric potential maps based on voltage detection in conducting paper are common practice in many physics courses in college. Most frequently, students work on `capacitor-like' geometries with current flowing between two opposite electrodes. A `topographical' investigation across the embedding medium (map of equipotential curves) allows to reassure a number of physical properties. This paper focuses on some less common configurations that bear pedagogical interest. We analyze `open-geometries' with electrodes in the form of long strips with slits. They provide a natural groundwork to bring the student to complex variable methods. Aided by this, we show that shaping the conducting paper board one may analyze finite size effects, as well as some meaningful discontinuities in the measured potential. The concept of conjugate electric potentials is exploited. Equipotentials and electric field lines acquire interchangeable roles and may be obtained in complementary `dual' experiments. A feasible theoretical analysis based on introductory complex variables and standardized numerics gives a remarkable quantification of the experimental results.Comment: 15 pages, 8 figure

Economic integration and regional inequality in Iberia (1900-2000) : a geographical approach

This paper studies the evolution of regional inequality in Iberia from 1900 to 2000 from a geographical perspective. For doing that the text presents a new dataset of historical regional GDPs for Spanish NUTS III and Portuguese Historical Districts (HD), synthetic indices of regional inequality and different measures of spatial correlation across regional pc GDPs. The results show that Portuguese and Spanish national economic integration processes initially favored the economic specialization across Iberian regions fostering the divergence in terms of their regional pc GDPs. Notwithstanding, ulterior advances in the integration of national markets and the subsequent first stages in the process of adhesion of these two national economies into the UE coexisted with a progressive reduction in Iberian regional inequality. So, Iberian regional inequality depicts a long term U-shaped evolution. Nevertheless, at the same time, Iberian regional inequality evolution followed a significant geographical pattern. The poorest regions cluster in inland territories of the south and west, with regions belonging to this cluster sited on the two sides of the political border. On the contrary, richest regions cluster along the coasts, especially in the north-east corner of the Iberian Peninsula. Besides, the data show that this pattern was well established in the middle of the XX century, before the reciprocal openness of national markets in the 1980s. In this respect, the adhesion of both economies to the UE in 1986 seems to have just caused an ulterior deepening in this historical patter

New Evidence on Regional Inequality in Iberia (1900-2000)

This article presents new evidence on the evolution of regional inequality in Iberia from 1900 to 2000 from a geographical perspective. To do so we introduce a new historical dataset of regional gross domestic products (GDPs) for Spanish NUTS III and Portuguese Historical Districts, synthetic indices of regional inequality, and different measures of spatial correlation across regional per capita GDPs. The results show that the Portuguese and Spanish national economic integration processes initially led to the economic specialization across Iberian regions promoting the divergence in terms of their regional per capita GDPs. Notwithstanding, ulterior advances in the integration of national markets and the subsequent first stages in the process of adhesion of these two national economies into the UE coexisted with a progressive reduction in Iberian regional inequality

Northwest Africa 5790. Top Sequence of the Nakhlite Pile

NWA 5790 is a recently discovered nakhlite. Its mineralogy, petrology and geochemistry suggest that it is the topmost sequence of the nakhlite lava pile

Magnetic quenching of positronium in thorium phosphate: an experimental approach to p-Ps pick-off lifetime ?

The effects of magnetic field (B) quenching on positronium (Ps) are studied in solid thorium phosphate by using both the lifetime spectroscopy (LS) and Doppler broadening (DBARL) techniques, in view of gaining information on the pick-off decay rate constant of positronium singlet state (p-Ps) and compare it to that of the triplet state (o-Ps). At B=0, the longest lifetime is [MATH] 700 ps, with an intensity of some 23 %. The effects of B on LS parameter R (normalized integral of counts in a time window) show that [MATH] is ascribable to o-Ps. Fitting the variations with B of both R and [MATH]4 (lifetime of the m=0 o-Ps substate) requires two phenomenological parameters : (i) the contact density parameter, [MATH]0.22 and (ii) either an additional contact density parameter, [MATH]0.36, or a p-Ps pick-off decay constant, [MATH], different from that of o-Ps, [MATH]. Resolving the deconvoluted DBARL spectra to derive the intensity of the intrinsic decay component at B=0 gives a better agreement with the first ([MATH]) than with the second ([MATH]) of these possibilities

A Call to Arms: Revisiting Database Design

Good database design is crucial to obtain a sound, consistent database, and - in turn - good database design methodologies are the best way to achieve the right design. These methodologies are taught to most Computer Science undergraduates, as part of any Introduction to Database class. They can be considered part of the "canon", and indeed, the overall approach to database design has been unchanged for years. Moreover, none of the major database research assessments identify database design as a strategic research direction. Should we conclude that database design is a solved problem? Our thesis is that database design remains a critical unsolved problem. Hence, it should be the subject of more research. Our starting point is the observation that traditional database design is not used in practice - and if it were used it would result in designs that are not well adapted to current environments. In short, database design has failed to keep up with the times. In this paper, we put forth arguments to support our viewpoint, analyze the root causes of this situation and suggest some avenues of research.Comment: Removed spurious column break. Nothing else was change

An inverse source problem for the heat equation and the enclosure method

An inverse source problem for the heat equation is considered. Extraction formulae for information about the time and location when and where the unknown source of the equation firstly appeared are given from a single lateral boundary measurement. New roles of the plane progressive wave solutions or their complex versions for the backward heat equation are given.Comment: 23page

Radiogenomics in clear cell renal cell carcinoma: correlations between advanced CT imaging (texture analysis) and microRNAs expression

Purpose: A relevant challenge for the improvement of clear cell renal cell carcinoma management could derive from the identification of novel molecular biomarkers that could greatly improve the diagnosis, prognosis, and treatment choice of these neoplasms. In this study, we investigate whether quantitative parameters obtained from computed tomography texture analysis may correlate with the expression of selected oncogenic microRNAs. Methods: In a retrospective single-center study, multiphasic computed tomography examination (with arterial, portal, and urographic phases) was performed on 20 patients with clear cell renal cell carcinoma and computed tomography texture analysis parameters such as entropy, kurtosis, skewness, mean, and standard deviation of pixel distribution were measured using multiple filter settings. These quantitative data were correlated with the expression of selected microRNAs (miR-21-5p, miR-210-3p, miR-185-5p, miR-221-3p, miR-145-5p). Both the evaluations (microRNAs and computed tomography texture analysis) were performed on matched tumor and normal corticomedullar tissues of the same patients cohort. Results: In this pilot study, we evidenced that computed tomography texture analysis has robust parameters (eg, entropy, mean, standard deviation) to distinguish normal from pathological tissues. Moreover, a higher coefficient of determination between entropy and miR-21-5p expression was evidenced in tumor versus normal tissue. Interestingly, entropy and miR-21-5p show promising correlation in clear cell renal cell carcinoma opening to a radiogenomic strategy to improve clear cell renal cell carcinoma management. Conclusion: In this pilot study, a promising correlation between microRNAs and computed tomography texture analysis has been found in clear cell renal cell carcinoma. A clear cell renal cell carcinoma can benefit from noninvasive evaluation of texture parameters in adjunction to biopsy results. In particular, a promising correlation between entropy and miR-21-5p was found