Josep Pascual Vila (1985-1979): una breu aproximació biogràfica

Es presenta una breu aproximació biogràfica de Josep Pascual Vila, catedràtic de química orgànica de la Universitat de Barcelona durant més de trenta anys. La seva trajectòria permet explicar l'evolució d'una escola de recerca iniciada a començaments dels anys vint i desenvolupada durant el franquisme.This is a brief biography of Josep Pascual Vila, professor of Organic Chemistry at the University of Barcelona for over thirty years. His career helps us to describe the evolution of a school of research that began in the 1920s and developed during the time of the Franco dictatorship

Enric Moles i Ormella (1883-1953) : un gran científic i un gran desconegut

In the context of the year commemorating Enric Moles, this paper makes a biographical sketch of this man, perhaps the most prestigious Catalan chemist in the first half of the 20th century. In addition to highlighting his contribution to the determination of atomic weights, a field in which he stood out in particular, we consider the latter years of his life and especially his exile, his return to Spain and his court-martial. Moles’ case is a clear example of the dramatic rupture produced in society by the Spanish Civil War and the Franco dictatorship. The recovery of our country’s historical memory requires that we study and spread the knowledge of such figures as Enric Moles and demand their acknowledgement.En el marc de l'Any Moles, aquest article presenta una aproximació a la biografia del químic català, segurament, de més prestigi internacional a la primera meitat del segle XX. A més de les seves aportacions a la determinació de pesos atòmics —camp en què destacà especialment—, es tracten en detall els últims anys de la seva vida, en concret, els de l'exili, el retorn i el consell de guerra a què fou sotmès. El seu és un cas ben representatiu del trencament dramàtic que suposaren la Guerra Civil i la dictadura franquista. La recuperació de la memòria històrica del país exigeix encara avui dia analitzar, difondre i reclamar la restitució de personalitats com Enric Moles

Neutron spectroscopy with the Spherical Proportional Counter

A novel large volume spherical proportional counter, recently developed, is used for neutron measurements. Gas mixtures of $N_{2}$ with $C_{2}H_{6}$ and pure $N_{2}$ are studied for thermal and fast neutron detection, providing a new way for the neutron spectroscopy. The neutrons are detected via the ${}^{14}N(n, p)C^{14}$ and ${}^{14}N(n, \alpha)B^{11}$ reactions. Here we provide studies of the optimum gas mixture, the gas pressure and the most appropriate high voltage supply on the sensor of the detector in order to achieve the maximum amplification and better resolution. The detector is tested for thermal and fast neutrons detection with a ${}^{252}Cf$ and a ${}^{241}Am-{}^{9}Be$ neutron source. The atmospheric neutrons are successfully measured from thermal up to several MeV, well separated from the cosmic ray background. A comparison of the spherical proportional counter with the current available neutron counters is also given.Comment: 7 pages, 10 figure

Exploring changes in open defecation prevalence in sub-Saharan Africa based on national level indices

Background In sub-Saharan Africa, it is estimated that 215 million people continue to engage in open defecation. This practice facilitates the transmission of diarrheal diseases – one of the leading causes of mortality in children under 5 in sub-Saharan Africa. The main purpose of this study is to: estimate changes in open defecation prevalence between 2005 and 2010 across countries in sub-Saharan Africa; examine the association between national level indices and changes in open defecation prevalence; and assess how many countries can achieve ‘open defecation free status’ by 2015. Methods After applying selection criteria, this study analyzed country-level data for 34 sub-Saharan African countries. Seven country-level indices were collected: 1) presence of a national sanitation policy; 2) budget line for sanitation; 3) budget allocated to sanitation; 4) annual per capita GDP; 5) GDP growth; 6) implementation of total sanitation approaches; and 7) per capita aid disbursement for water supply and sanitation. The relationships between these country-level indices and the change in open defecation from 2005 to 2010 were investigated using Wilcoxon Signed-Rank test and Spearman\u27s rank correlation test. Results Only 3 countries (i.e. Ethiopia, Angola and Sao Tome and Principe) decreased open defecation by 10% or more between 2005 and 2010. No significant associations were observed between the change in open defecation prevalence and all of national level indices except per capita aid disbursement. Per capita aid disbursement for water and sanitation was positively associated with a reduction in open defecation (p-value = 0.02) for a subset of 29 low-income countries from 2005 to 2010. Only one country in our analysis, Angola, is on track to end open defecation by 2015 based on their performance between 2000 and 2010. Conclusions Most of the national level indices, including a country’s economic status, were not associated with the change in the open defecation prevalence. Based on current trends, the goal of ending open defecation in the majority of sub-Saharan African countries by 2015 will not be achieved. Our findings may be limited by the exploratory nature of this analysis, and future research is required to identify and characterize national level factors specific to reducing open defecation in sub-Saharan Africa

All-optical attoclock: accessing exahertz dynamics of optical tunnelling through terahertz emission

The debate regarding attosecond dynamics of optical tunneling has so far been focused on time delays associated with electron motion through the potential barrier created by intense ionizing laser fields and the atomic core. Compelling theoretical and experimental arguments have been put forward to advocate the polar opposite views, confirming or refuting the presence of tunnelling time delays. Yet, such delay, whether present or ot, is but a single quantity characterizing the tunnelling wavepacket; the underlying dynamics are richer. Here we propose to complement photo-electron detection with detecting light, focusing on the so-called Brunel adiation -- the near-instantaneous nonlinear optical response triggered by the tunnelling event. Using the combination of single-color and two-color driving fields, we determine not only the ionization delays, but also the re-shaping of the tunnelling wavepacket as it emerges from the classically forbidden region. Our work introduces a new type of attoclock for optical tunnelling, one that is based on measuring light rather than photo-electrons. All-optical detection paves the way to time-resolving multiphoton transitions across bandgaps in solids, on the attosecond time-scale