336 research outputs found

    Infinite-dimensional representations of the rotation group and Dirac's monopole problem

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    Within the context of infinite-dimensional representations of the rotation group the Dirac monopole problem is studied in details. Irreducible infinite-dimensional representations, being realized in the indefinite metric Hilbert space, are given by linear unbounded operators in infinite-dimensional topological spaces, supplied with a weak topology and associated weak convergence. We argue that an arbitrary magnetic charge is allowed, and the Dirac quantization condition can be replaced by a generalized quantization rule yielding a new quantum number, the so-called topological spin, which is related to the weight of the Dirac string.Comment: JHEP style. Extended version of hep-th/0403146. Revised version, title and some notations are changed. References and Appendix B are adde

    Social investment in Spain: How do solidarity mutual funds decide the allocation of solidarity funding between social economy organizations?

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    Solidarity mutual funds (SMFs) are a financial product oriented toward funding social economy organizations (SEOs). The main characteristic of these mutual funds, known in other countries as social investment, is that part of their management fees is allocated to support SEOs. In Spain, the criteria used in the allocation process of these funds have not been studied. The aim of this paper is to analyze the decision model of SMFs. To this end, we developed a logit regression model. The obtained results show that the decision model of SMFs promotes the development of commercial activity and favors a specific ideology and values and an exclusive relationship with the main funders

    Characterization and wear performance of boride phases over tool steel substrates

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    This research work was conducted to characterize boride phases, obtained from the powder-pack process, on AISI H13 and D2 steel substrates, and investigate their tribological behavior. The boriding was developed at a temperature of 1273 K with an exposure time of 8 h. X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were conducted on the borided material to characterize the presence of the FeB, Fe2B, and CrB phases and the distribution of heavy elements on the surface of the substrates. The adherence of the boride layers was evaluated, in a qualitative form, through the Daimler-Benz Rockwell-C indentation technique. Sliding wear tests were then performed using a reciprocating wear test machine. All tests were conducted in dry conditions at room temperature. A frequency of 10 Hz and 15-mm sliding distance were used. The applied Hertzian pressure was 2.01 GPa. Scanning electron microscopy was used to observe and analyze the wear mechanisms. Additionally, the variation of the friction coefficient versus the number of cycles was obtained. Experimental results showed that the characteristic wear mechanism for the borided surface was plastic deformation and mild abrasive wear; for unborided substrates, cracking and spalling were observed

    Modelling of surface and inner wall temperatures in the analysis of courtyard thermal performances in Mediterranean climates

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    Courtyards are an effective passive strategy for improving the energy performance of buildings. However, there is a lack of accurate simulation tools for their thermal performance due to their complex thermodynamics. This paper’s contribution is the coupling of a CFD model with a system of differential equations at the walls, governing surface and inner wall temperatures, providing an accurate computation of courtyard thermal performance. On this basis, boundary conditions for the standard Boussinesq equations governing temperatures, wind velocity, and pressure within the courtyard are established. Modelling results are compared with monitored data in two days of different months in a courtyard in Seville (Spain). Simultaneously, simulations carried out by existing software were performed. Resulting data showed more accuracy than existing tools, with a Root Mean Square Error of 1.19 (August) and 1.59 (October), while the corresponding values with ENVI-met were 3.31-3.4, and with Ladybug Tools 2.59-4.49.Ministerio de Economía y Competitividad MTM2015-64577-C2-1-RMinisterio de Economía y Competitividad MTM2015-64577-C2-2-RMinisterio de Ciencia, Innovación y Universidades RTI2018-093521-B-C31Ministerio de Ciencia, Innovación y Universidades RTI2018-093521-B-C33Ministerio de Educación, Cultura y Deporte FPU17/0503

    Sex-specific behavioral and neurogenic responses to cocaine in mice lacking and blocking dopamine D1 or dopamine D2 receptors

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    Adult neurogenesis in rodents is modulated by dopaminergic signaling and inhibited by cocaine. However, the sex-specific role of dopamine D1 and D2 receptors (D1R, D2R) in the deleterious effect of cocaine on adult neurogenesis has not been described yet. Here, we explored sex differences in (a) cell proliferation (5′-bromo-2′-deoxyuridine [BrdU]), (b) neural precursor (nestin), (c) neuronal phenotype (BrdU/β3-tubulin), and (d) neuronal maturity (NeuN) in the subventricular zone (SVZ) of the lateral ventricles and striatum of mice with genetic deletion (D1, D2) or pharmacological blockage (SCH23390: 0.1 mg/kg/day/5 days; Raclopride: 0.3 mg/kg/day/5 days) of D1R and D2R, and treated (10 mg/kg/day/5 days) and then challenged (5 mg/kg, 48 hr later) with cocaine. Results indicated that hyperactivity responses to cocaine were absent in D1 mice and reduced in SCH23390-treated mice. Activity responses to cocaine were reduced in D2 males, but absent in D2 females and increased in Raclopride-treated females. D1R deletion blocked the deleterious effect of cocaine on SVZ cell proliferation in males. Cocaine-exposed D1 males also had reduced neuronal phenotype of SVZ newborn cells and increased striatal neuronal maturity. D2 mice had lower proliferative and neural precursor responses. Cocaine in D2 females or coadministered with Raclopride in wild-type females improved SVZ cell proliferation, an effect that positively correlated with plasma brain-derived neurotrophic factor (BDNF) concentrations. In conclusion, the sex-specific D1R and D2R signaling on SVZ cell proliferation, neural progenitor and neuronal maturity is differentially perturbed by cocaine, and BDNF may be required to link D2R to neuroplasticity in cocaine addiction in females.Consejería de Salud, Junta de Andalucía, Grant/Award Number: C1-0049-2019; Instituto de Salud Carlos III, Grant/Award Numbers: CP19/00068, CPII17/00024, CPII19/00022, CPII19/00031, PI19/01577, PI19/00886, PI17/02026, RD16/0017/0001; Ministerio de Sanidad, Servicios Sociales e Igualdad, Grant/Award Numbers: PND2017/043, PND2018/033, PND2018/044, PND2019/04

    Guillain-Barré syndrome following the 2009 pandemic monovalent and seasonal trivalent influenza vaccination campaigns in Spain from 2009 to 2011: Outcomes from active surveillance by a neurologist network, and records from a country-wide hospital discharge database

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    Background: Studies have shown a slight excess risk in Guillain-Barré syndrome (GBS) incidence associated with A(H1N1)pdm09 vaccination campaign and seasonal trivalent influenza vaccine immunisations in 2009-2010. We aimed to assess the incidence of GBS as a potential adverse effect of A(H1N1)pdm09 vaccination. Methods: A neurologist-led network, active at the neurology departments of ten general hospitals serving an adult population of 4.68 million, conducted GBS surveillance in Spain in 2009-2011. The network, established in 1996, carried out a retrospective and a prospective study to estimate monthly alarm thresholds in GBS incidence and tested them in 1998-1999 in a pilot study. Such incidence thresholds additionally to observation of GBS cases with immunisation antecedent in the 42 days prior to clinical onset were taken as alarm signals for 2009-2011, since November 2009 onwards. For purpose of surveillance, in 2009 we updated both the available centres and the populations served by the network. We also did a retrospective countrywide review of hospital-discharged patients having ICD-9-CM code 357.0 (acute infective polyneuritis) as their principal diagnosis from January 2009 to December 2011. Results: Among 141 confirmed of 148 notified cases of GBS or Miller-Fisher syndrome, Brighton 1-2 criteria in 96 %, not a single patient was identified with clinical onset during the 42-day time interval following A(H1N1)pdm09 vaccination. In contrast, seven cases were seen during a similar period after seasonal campaigns. Monthly incidence figures did not, however, exceed the upper 95 % CI limit of expected incidence. A retrospective countrywide review of the registry of hospital-discharged patients having ICD-9-CM code 357.0 (acute infective polyneuritis) as their principal diagnosis did not suggest higher admission rates in critical months across the period December 2009-February 2010. Conclusions: Despite limited power and underlying reporting bias in 2010-2011, an increase in GBS incidence over background GBS, associated with A(H1N1)pdm09 monovalent or trivalent influenza immunisations, appears unlikely

    Forage yield of Urochloa cultivars in a warm sub-humid environment

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    Objective: Evaluate for 10 weeks the growth of five Urochloa cultivars: Camello, Cobra, Cayman, Convert 330, Mavuno and Xaraés; during the Nortes (NS), Drought (DS) and Rainy (RS) seasons in a humid semi-warm environment. Design/methodology/approach: Variables were crop growth rate (CGR; kg ha-1 d-1) and total dry matter yield (TDM; t ha-1); which were analyzed under a completely randomized design (Tukey; p=0.05). Results: During NS, Mavuno and Xaraés presented, on average, the highest values ??of CGR (p<0.05), 23.7 and 19.4 kg ha-1 d-1, respectively. In DS the cultivars Xaraés, Convert 330, Mavuno and Cayman, presented the highest values, with 20.7 and 26.8 kg ha-1 d-1, in week 2 and 4, respectively. During RS, in the second and fourth week of regrowth, the Xaraés and Mavuno cultivars presented the highest CGR (p<0.05), 119.8 and 144.7 kg ha-1 d-1, on average. In the NS, the Mavuno hybrid presented the highest yields (p<0.05) of TDM, 0.886, 1.553 and 2.156 t ha-1 in week 6, 8 and 10, respectively. For RS, the cultivars Camello, Cayman, Mavuno and Xaraés presented similar yields of TDM; which, on average, were 4.652, 5.312 and 6.278 t ha-1, at 6, 8 and 10 weeks, respectively. Findings/conclusions: The cultivars Xaraés, Mavuno and Cayman presented good forage potential in a humid semi-warm environment; mainly for showing greater growth and accumulation of total dry matter.Objective: To evaluate for 10 weeks the growth of five Urochloa cultivars: Camello,Cobra, Cayman, Convert 330, Mavuno and Xaraés; during the North Winds (NS), Dry(DS) and Rainy (RS) seasons in a warm sub-humid environment. Design/Methodology/Approach: The variables were crop growth rate (CGR; kg ha-1 d-1 ) and total dry matter yield (TDM; t ha -1 ); which were analyzed under a completelyrandomized design (Tukey; p=0.05). Results: During NS, Mavuno and Xaraés presented, on average, the highest values ??ofCGR (p<0.05), 23.7 and 19.4 kg ha-1 d-1, respectively. In DS the cultivars Xaraés,2Convert 330, Mavuno, and Cayman presented the highest values, with 20.7 and 26.8 kgha-1 d-1 , in week 2 and 4, respectively. During RS, in the second and fourth week ofregrowth, the Xaraés and Mavuno cultivars presented the highest CGR (p<0.05), 119.8and 144.7 kg ha-1 d-1 , on average. In the NS, the Mavuno hybrid presented the highestyields (p<0.05) of TDM, 0.886, 1.553 and 2.156 t ha -1 in week 6, 8 and 10, respectively.For RS, the cultivars Camello, Cayman, Mavuno, and Xaraés presented similar yields ofTDM; which, on average, were 4.652, 5.312 and 6.278 t ha -1 , at 6, 8 and 10 weeks,respectively. Findings/Conclusions: The cultivars Xaraés, Mavuno and Cayman presented goodforage potential in a warm sub-humid environment; mainly for showing greater growthand accumulation of total dry matter

    Changing state of the climate system

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    Chapter 2 assesses observed large-scale changes in climate system drivers, key climate indicators and principal modes of variability. Chapter 3 considers model performance and detection/attribution, and Chapter 4 covers projections for a subset of these same indicators and modes of variability. Collectively, these chapters provide the basis for later chapters, which focus upon processes and regional changes. Within Chapter 2, changes are assessed from in situ and remotely sensed data and products and from indirect evidence of longer-term changes based upon a diverse range of climate proxies. The time-evolving availability of observations and proxy information dictate the periods that can be assessed. Wherever possible, recent changes are assessed for their significance in a longer-term context, including target proxy periods, both in terms of mean state and rates of change
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