Near-IR internetwork spectro-polarimetry at different heliocentric angles

The analysis of near infrared spectropolarimetric data at the internetwork at different regions on the solar surface could offer constraints to reject current modeling of these quiet areas. We present spectro-polarimetric observations of very quiet regions for different values of the heliocentric angle for the Fe I lines at 1.56 micron, from disc centre to positions close to the limb. The spatial resolution of the data is 0.7-1". We analyze direct observable properties of the Stokes profiles as the amplitude of circular and linear polarization as well as the total degree of polarization. Also the area and amplitude asymmetries are studied. We do not find any significant variation of the properties of the polarimetric signals with the heliocentric angle. This means that the magnetism of the solar internetwork remains the same regardless of the position on the solar disc. This observational fact discards the possibility of modeling the internetwork as a Network-like scenario. The magnetic elements of internetwork areas seem to be isotropically distributed when observed at our spatial resolution.Comment: Sorry, this is the version with the correct bibliography. Some figures had to be compressed. Accepted for publication in A&

Four essays on the 1994 Mexican crisis

Most of the thesis is devoted to studying the collapse of the Mexican peso in December 1994 using empirical methods that allow shifts in regimes, as well as a small theoretical model based on the escape clause approach. Also, we present a study of the consumption boom observed in Mexico in the period 1989-1994 to highlight the importance of taking into account structural breaks in co-integration modelling. We use a series of realignment expectations, as well as linear and non-linear methods, to look for evidence that helps to characterise the Mexican crisis. Contrary to the predictions of first-generation models of currency crises, we find that the credibility of the peso did not experience any steady deterioration before its devaluation, and there was no stable relationship between realignment expectations and economic fundamentals. By using a Markov-switching regression model, we show that realignment expectations shifted over time between regimes of relatively high and low credibility, and that these shifts were more frequent during the troubled 1994. This evidence makes it problematic to endorse explanations of the collapse of the peso based on models of speculative attacks, and suggests using the approach of second-generation models of currency crises to study the Mexican experience. The theoretical model is designed to illustrate some specific features of the Mexican experience. We argue that the substitution of peso denominated assets for dollar denominated and indexed assets in investors’ portfolios helped policymakers to resist recurrent periods of confidence crisis during 1994, but it also made it more difficult to eliminate a potential self-fulfilling devaluation. In particular, the sterilisation of reserve losses during 1994 seems to be more important in the onset of the devaluation of the peso than the increase in the stock of dollar indexed bonds. We use an index of pressure in the foreign exchange market and mean-variance Markov- switching models to study the timing and causes of the shifts of the Mexican economy between states of calm and crisis. Models with time-varying transition probabilities do not yield conclusive results. Hence, we adopt a two step approach to obtain the probability of the state of crisis at each date in the sample, and then model this series as a function of economic fundamentals and political events. We find that the reduction of the debt-output ratio and positive political events maintained the economy in the state of calm up to 1994, despite a continuous real appreciation of the peso. However, the end of the declining path of the debt-output ratio and negative political shocks produced a shift towards the state of crisis for most of 1994 that finally led to the collapse of the peso. The study of the consumption boom observed in Mexico in the period 1989-1994 illustrates that structural breaks in long run relationships can be dated and evaluated if we allow regime shifts in co-integration modelling. The available data rejects a stable co-integration relationship between consumption and income. Meanwhile, using Markov- switching models, we find that there was a marked shift in the co-integration vector after the implementation of the program for stabilisation and economic reform in December 1987. The program caused the former unitary income elasticity of consumption to increase by almost 30 per cent, but later the shift was reversed when the currency and financial crisis erupted at the end of 1994

OH rotational lines as a diagnostic of the warm neutral gas in galaxies

We present Infrared Space Observatory (ISO) observations of several OH, CH and H2O rotational lines toward the bright infrared galaxies NGC253 and NGC1068. As found in the Galactic clouds in SgrB2 and Orion, the extragalactic far-IR OH lines change from absorption to emission depending on the physical conditions and distribution of gas and dust along the line of sight. As a result, most of the OH rotational lines that appear in absorption toward NGC253 are observed in emission toward NGC1068. We show that the far-IR spectrum of OH can be used as a powerful diagnostic to derive the physical conditions of extragalactic neutral gas. In particular, we find that a warm (Tk~150 K, n(H2)< 5 10^4 cm^-3) component of molecular gas with an OH abundance of 10^{-7} from the inner <15'' can qualitatively reproduce the OH lines toward NGC253. Similar temperatures but higher densities (5 10^5 cm^-3) are required to explain the OH emission in NGC1068.Comment: 5 pages, 4 figures, accepted in ApJ Part I (2004, October 6

Avaliação de acessos de Centrosema pubescens em regiões secas do estado de Zulia, Venezuela

Se evaluaron veinticinco accesiones de Centrosema pubescens, dos de Centrosema acutifolium y una de Centrosema brasilianum, en cuanto a adaptación, producción de materia seca (DMP), contenido de proteína cruda (CP), digestibilidad de materia orgánica in vitro (IVOMD), características de crecimiento y pureza. producción de semillas, en dos regiones del estado Zulia, Venezuela: “El Laberinto” (franco arenoso Alfisol; precipitación anual de 971 mm; bosque tropical seco), y “La Cañada” (franco arenoso Aridisol; precipitación anual de 600 mm; tropical muy seco bosque). Las accesiones se plantaron en un diseño de bloques completamente al azar, con tres repeticiones. Las evaluaciones se realizaron cada 12 semanas tanto durante la estación lluviosa (RS) como en la estación seca (DS). En “El Laberinto” se destacaron las accesiones de C. pubescens 15 160, 5 169, 5 627, 15 133, 438, 5 167, 5 189, 15 872 y 15 144, con un DMP de 12,96 a 9,84 t / ha. CP fue 18,76% en DS y 21,41% en RS. Inversamente, el IVMOD fue mayor durante el DS (56%) que en el RS (46,6%). En “La Cañada”, C. pubescens 15 150 presentó el mayor DMP con 13,5 t / ha, seguido por C. acutifolium 5 568, C. pubescens 15 144 y 15 160 con 10,4, 10,32 y 10,24 t / ha, respectivamente. La CP fue del 16,74% en DS y del 18,73% en RS. Nuevamente, el IVMOD fue mayor en DS (54,5%) que en RS (53,74%). C. pubescens 15 160, 5 167, 5 169 y 5 189 son las accesiones más prometedoras para “El Laberinto” y C. pubescens 15 150, 15 160, 15 144, 5 627 y C. acutifolium 5 568 para “La Cañada ”.Twenty five accessions of Centrosema pubescens, two of Centrosema acutifolium, and one of Centrosema brasilianum, were evaluated for adaptation, dry matter production (DMP), crude protein (CP) content, in vitro organic matter digestibility (IVOMD), growth characteristics and pure seed production, in two regions of Zulia State, Venezuela: “El Laberinto” (sandy loam Alfisol ; annual rainfall of 971mm; dry tropical forest), and “La Cañada”(sandy loam Aridisol; annual rainfall of 600 mm; very dry tropical forest). The accessions were planted in a completly randomized block design, with three replications. Evaluations were made every 12 weeks during both rainy (RS) and dry season (DS). At “El Laberinto” the C. pubescens accessions 15 160, 5 169, 5 627, 15 133, 438, 5 167, 5 189, 15 872, and 15 144 were outstanding, with DMP ranging from 12.96 to 9.84 t/ha. CP was 18.76% in DS, and 21.41% in RS. Inversely, IVMOD was higher during the DS (56%) than in the RS (46.6%). At “La Cañada”, C. pubescens 15 150 had the highest DMP with 13.5 t/ha, followed by C. acutifolium 5 568, C. pubescens 15 144 and 15 160 with 10.4, 10.32, and 10.24 t/ha, respectively. CP was 16.74% in DS, and 18.73% in RS. Again, IVMOD was higher in DS (54.5%) than in RS (53.74%). C. pubescens 15 160, 5 167, 5 169 y 5 189 are the most promising accessions for “El Laberinto” and C. pubescens 15 150, 15 160, 15 144, 5 627, and C. acutifolium 5 568 for “La Cañada”.Vinte e cinco acessos de Centrosema pubescens, dois de Centrosema acutifolium e um de Centrosema brasilianum foram avaliados quanto à adaptação, produção de matéria seca (DMP), teor de proteína bruta (PB), digestibilidade in vitro da matéria orgânica (DIVMO), características de crescimento e pureza produção de sementes, em duas regiões do estado de Zulia, Venezuela: “El Laberinto” (Alfisol franco-arenoso; precipitação anual de 971 mm; floresta tropical seca) e “La Cañada” (Aridisol franco-arenoso; precipitação anual de 600 mm; tropical muito seco floresta). Os acessos foram plantados em delineamento de blocos ao acaso, com três repetições. As avaliações foram feitas a cada 12 semanas durante a estação chuvosa (RS) e seca (DS). Em “El Laberinto” os acessos de C. pubescens 15 160, 5 169, 5 627, 15 133, 438, 5 167, 5 189, 15 872 e 15 144 foram excelentes, com DMP variando de 12,96 a 9,84 t / ha. CP foi de 18,76% no DS e 21,41% no RS. Inversamente, o IVMOD foi maior no SD (56%) do que no RS (46,6%). Em “La Cañada”, C. pubescens 15 150 teve o maior DMP com 13,5 t / ha, seguido por C. acutifolium 5 568, C. pubescens 15 144 e 15 160 com 10,4, 10,32 e 10,24 t / ha, respectivamente. CP foi de 16,74% no DS e 18,73% no RS. Novamente, o IVMOD foi maior no DS (54,5%) do que no RS (53,74%). C. pubescens 15 160, 5 167, 5 169 e 5 189 são os acessos mais promissores para “El Laberinto” e C. pubescens 15 150, 15 160, 15 144, 5 627 e C. acutifolium 5 568 para “La Cañada ”

Interactions and scattering of quantum vortices in a polariton fluid

Quantum vortices, the quantized version of classical vortices, play a prominent role in superfluid and superconductor phase transitions. However, their exploration at a particle level in open quantum systems has gained considerable attention only recently. Here we study vortex pair interactions in a resonant polariton fluid created in a solid-state microcavity. By tracking the vortices on picosecond time scales, we reveal the role of nonlinearity, as well as of density and phase gradients, in driving their rotational dynamics. Such effects are also responsible for the split of composite spin-vortex molecules into elementary half-vortices, when seeding opposite vorticity between the two spinorial components. Remarkably, we also observe that vortices placed in close proximity experience a pull-push scenario leading to unusual scattering-like events that can be described by a tunable effective potential. Understanding vortex interactions can be useful in quantum hydrodynamics and in the development of vortex-based lattices, gyroscopes, and logic devices.Comment: 12 pages, 7 figures, Supplementary Material and 5 movies included in arXi

Potassium fertilisation and the thermal behaviour of Cynara cardunculus L.

Herbaceous biomass like Cynara is commonly high in potassium, chlorine and ash, which has been reported as a source of problems for combustion applications. An appropriate management of the potassium fertilisation is suggested as a way of improving the quality of the Cynara biomass for solid fuel applications. In this work a factorial experiment was designed involving two types of fertilisers, KCl and K2SO4, and two K rates, in order to study the effect of potassium fertilisation on the composition and thermal behaviour of Cynara biomass. The results proved that the potassium content of Cynara biomass increases with the potassium fertilisation. The thermogravimetric study showed that sintering phenomena can be expected at temperatures higher than 900 °C when the crop has been highly K-fertilised, irrespective of the type of fertiliser used, KCl or K2SO4. However, the SEM images taken of samples of the four K treatments of this experiment did not reveal signs of ash melting, although some particles with crystalline appearance appeared in the samples from highly K-fertilised treatments

Machine learning to refine decision making within a syndromic surveillance service

Background: Worldwide, syndromic surveillance is increasingly used for improved and timely situational awareness and early identification of public health threats. Syndromic data streams are fed into detection algorithms, which produce statistical alarms highlighting potential activity of public health importance. All alarms must be assessed to confirm whether they are of public health importance. In England, approximately 100 alarms are generated daily and, although their analysis is formalised through a risk assessment process, the process requires notable time, training, and maintenance of an expertise base to determine which alarms are of public health importance. The process is made more complicated by the observation that only 0.1% of statistical alarms are deemed to be of public health importance. Therefore, the aims of this study were to evaluate machine learning as a tool for computer-assisted human decision-making when assessing statistical alarms. Methods: A record of the risk assessment process was obtained from Public Health England for all 67505 statistical alarms between August 2013 and October 2015. This record contained information on the characteristics of the alarm (e.g. size, location). We used three Bayesian classifiers- naïve Bayes, tree-augmented naïve Bayes and Multinets - to examine the risk assessment record in England with respect to the final ‘Decision’ outcome made by an epidemiologist of ‘Alert’, ‘Monitor’ or ‘No-action’. Two further classifications based upon tree-augmented naïve Bayes and Multinets were implemented to account for the predominance of ‘No-action’ outcomes. Results: The attributes of each individual risk assessment were linked to the final decision made by an epidemiologist, providing confidence in the current process. The naïve Bayesian classifier performed best, correctly classifying 51.5% of ‘Alert’ outcomes. If the ‘Alert’ and ‘Monitor’ actions are combined then performance increases to 82.6% correctly classified. We demonstrate how a decision support system based upon a naïve Bayes classifier could be operationalised within an operational syndromic surveillance system. Conclusions: Within syndromic surveillance systems, machine learning techniques have the potential to make risk assessment following statistical alarms more automated, robust, and rigorous. However, our results also highlight the importance of specialist human input to the process

Identification of Neural Circuits by Imaging Coherent Electrical Activity with FRET-Based Dyes

AbstractWe show that neurons that underlie rhythmic patterns of electrical output may be identified by optical imaging and frequency-domain analysis. Our contrast agent is a two-component dye system in which changes in membrane potential modulate the relative emission between a pair of fluorophores. We demonstrate our methods with the circuit responsible for fictive swimming in the isolated leech nerve cord. The output of a motor neuron provides a reference signal for the phase-sensitive detection of changes in fluorescence from individual neurons in a ganglion. We identify known and possibly novel neurons that participate in the swim rhythm and determine their phases within a cycle. A variant of this approach is used to identify the postsynaptic followers of intracellularly stimulated neurons

Pre-exenterative chemotherapy, a novel therapeutic approach for patients with persistent or recurrent cervical cancer

BACKGROUND: Most cervical cancer patients with pelvic recurrent or persistent disease are not candidates for exenteration, therefore, they only receive palliative chemotherapy. Here we report the results of a novel treatment modality for these patients pre-exenterative chemotherapy- under the rational that the shrinking of the pelvic tumor would allow its resection. METHODS: Patients with recurrent or persistent disease and no evidence of systemic disease, considered not be candidates for pelvic exenteration because of the extent of pelvic tumor, received 3-courses of platinum-based chemotherapy. Response was evaluated by CT scan and bimanual pelvic examination; however the decision to perform exenteration relied on the physical findings. Toxicity to chemotherapy was evaluated with standard criteria. Survival was analyzed with the Kaplan-Meier method. RESULTS: Seventeen patients were studied. The median number of chemotherapy courses was 4. There were 9 patients who responded to chemotherapy, evaluated by bimanual examination and underwent pelvic exenteration. Four of them had pathological complete response. Eight patients did not respond and were not subjected to surgery. One patient died due to exenteration complications. At a median follow-up of 11 months, the median survival for the whole group was 11 months, 3 months in the non-operated and 32 months in those subjected to exenteration. CONCLUSION: Pre-exenterative chemotherapy is an alternative for cervical cancer patients that are no candidates for exenteration because of the extent of the pelvic disease. Its place in the management of recurrent disease needs to be investigated in randomized studies, however, its value for offering long-term survival in some of these patients with no other option than palliative care must be stressed

IFE Plant Technology Overview and contribution to HiPER proposal

HiPER is the European Project for Laser Fusion that has been able to join 26 institutions and signed under formal government agreement by 6 countries inside the ESFRI Program of the European Union (EU). The project is already extended by EU for two years more (until 2013) after its first preparatory phase from 2008. A large work has been developed in different areas to arrive to a design of repetitive operation of Laser Fusion Reactor, and decisions are envisioned in the next phase of Technology Development or Risk Reduction for Engineering or Power Plant facilities (or both). Chamber design has been very much completed for Engineering phase and starting of preliminary options for Reactor Power Plant have been established and review here