4,253 research outputs found

    Type-4 spinors: transmuting from Elko to single-helicity spinors

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    In this communication we briefly report an unexpected theoretical discovery which emerge from the mapping of Elko mass-dimension-one spinors into single helicity spinors. Such procedure unveils a class of spinor which is classified as type-4 spinor field within Lounesto classification. In this paper we explore the underlying physical and mathematical contents of the type-4 spinor.Comment: 9 pages, 0 figure

    El águila y el dragón: la batalla del nuevo milenio

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    Irak, Estados Unidos e Inglaterra han estado en el ojo del huracán debido a la incursión bélica que estos últimos dos realizaron en el 2003 para derrocar al régimen iraquí a pesar de la oposición de muchos países en el Consejo de Seguridad de la ONU

    Cute hypotensor effect of the vascular occlusion exercise on elderly adults

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    Objetivo: El objetivo de este estudio fue evaluar la respuesta cardíaca aguda después de realizar una sesión de ejercicio con oclusión vascular en adultos mayores (AM). Sujetos y método: 22 participantes voluntarios, fueron sometidos al protocolo experimental de ejercicio dinámico de prensión manual con un 30% de presión de oclusión (PO), después de registrar los valores basales y en reposo de presión arterial sistólica (PAS), presión arterial diastólica (PAD) y frecuencia cardíaca (FC). Evaluadas en condiciones basales y entre los 5 y 30 minutos post-oclusión. Resultados: Al finalizar el protocolo se observó una reducción significativa en la PAS y FC a los 15’, 20’ y 25’ (p<0,05) y para la PAD a los 10’ y 20’ (p<0,05). Conclusión: El efecto agudo del ejercicio con oclusión vascular genera una reducción significativa de PAS, PAD y FC hasta 25 minutos post-oclusión, en los AM analizadosThe objective of this study was to evaluate the acute cardiac response after performing an exercise session with vascular occlusion in elderly adults (EA). Twenty-two volunteer participants underwent the experimental protocol of dynamic manual grip exercise with 30% occlusion pressure (OP), after recording the baseline values and resting systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR). All measures were taken in basal conditions and between 5 and 30 minutes’ post-occlusion. At the end of the protocol, there was a significant reduction in SBP and HR at 15 ', 20' and 25 '(p <0.05) and for DBP at 10' and 20 '(p <0.05).). The acute effect of exercise with vascular occlusion generates a significant reduction of SBP, Basal Diastolic Pressure (BDP) and HR up to 25 minutes’ post-occlusion, in the EA analyze

    Ammonium chloride ingestion attenuates exercise-induced mRNA levels in human muscle

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    Minimizing the decrease in intracellular pH during high-intensity exercise training promotes greater improvements in mitochondrial respiration. This raises the intriguing hypothesis that pH may affect the exercise-induced transcription of genes that regulate mitochondrial biogenesis. Eight males performed 10x2-min cycle intervals at 80% VO2speak intensity on two occasions separated by ~2 weeks. Participants ingested either ammonium chloride (ACID) or calcium carbonate (PLA) the day before and on the day of the exercise trial in a randomized, counterbalanced order, using a crossover design. Biopsies were taken from the vastus lateralis muscle before and after exercise. The mRNA level of peroxisome proliferator-activated receptor co-activator 1α (PGC-1α), citrate synthase, cytochome c and FOXO1 was elevated at rest following ACID (P<0.05). During the PLA condition, the mRNA content of mitochondrial- and glucose-regulating proteins was elevated immediately following exercise (P<0.05). In the early phase (0-2 h) of post-exercise recovery during ACID, PGC-1α, citrate synthase, cytochome C, FOXO1, GLUT4, and HKII mRNA levels were not different from resting levels (P>0.05); the difference in PGC-1α mRNA content 2 h post-exercise between ACID and PLA was not significant (P = 0.08). Thus, metabolic acidosis abolished the early post-exercise increase of PGC-1α mRNA and the mRNA of downstream mitochondrial and glucose-regulating proteins. These findings indicate that metabolic acidosis may affect mitochondrial biogenesis, with divergent responses in resting and post-exercise skeletal muscle

    A study of the etapipi channel produced in central pp interactions at 450 GeV/c

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    The reaction pp -> pf (eta pi pi) ps has been studied at 450 GeV/c. There is clear evidence for an a2(1320)pi decay mode of the eta2(1645) and eta2(1870). In addition, there is evidence for an a0(980)pi$ decay mode of both resonances and an f2(1270)eta decay mode of the eta2(1870). No evidence is found for a JPC = 2++ a2(1320)pi wave.Comment: 15 pages, Latex, 4 Figures Branching ratio a2pi /f2 eta correcte

    On extending actions of groups

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    Problems of dense and closed extension of actions of compact transformation groups are solved. The method developed in the paper is applied to problems of extension of equivariant maps and of construction of equivariant compactifications

    A study of the f0(1370), f0(1500), f0(2000) and f2(1950) observed in the centrally produced 4pi final states

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    The production and decay properties of the f0(1370), f0(1500), f0(2000) and f2(1950) have been studied in central pp interactions at 450 GeV/c. The dPT, phi and |t| distributions of these resonances are presented. For the J = 0 states, the f0(1370) and f0(2000) have similar dPT and phi dependences. These are different to the dPT and phi dependences of the f0(980), f0(1500) and f0(1710). For the J = 2 states the f2(1950) has different dependences to the f2(1270) and f2'(1520). This shows that the dPT and phi dependences are not just J phenomena.Comment: 14 pages, Latex, 4 Figure

    A study of pseudoscalar states produced centrally in pp interactions at 450 GeV/c

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    A study has been made of pseudoscalar mesons produced centrally in pp interactions. The results show that the eta and etaprime appear to have a similar production mechanism which differs from that of the pi0. The production properties of the eta and etaprime are not consistent with what is expected from double Pomeron exchange. In addition the production mechanism for the eta and etaprime is such that the production cross section are greatest when the azimuthal angle between the pT vectors of the two protons is 90 degrees.Comment: 11 pages, Latex, 3 Figure

    A partial wave analysis of the centrally produced K+K- and K0K0 systems in pp interactions at 450 GeV/c and new information on the spin of the fJ(1710)

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    A partial wave analysis of the centrally produced K+K- and K0K0 channels has been performed in pp collisions using an incident beam momentum of 450 GeV/c. An unambiguous physical solution has been found in each channel. The striking feature is the observation of peaks in the S-wave corresponding to the f0(1500) and fJ(1710) with J = 0. The D-wave shows evidence for the f2(1270)/a2(1320), the f2(1525) and the f2(2150) but there is no evidence for a statistically significant contribution in the D-wave in the 1.7 GeV mass region.Comment: 15 pages, Latex, 5 Figure

    A partial wave analysis of the centrally produced pi+pi- system in pp interactions at 450 GeV/c

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    A partial wave analysis of the centrally produced pi+pi- channel has been performed in pp collisions using an incident beam momentum of 450 GeV/c. An unambiguous physical solution has been found. Evidence is found for the f0(980), f0(1300), f0(1500) and fJ(1710) with J = 0 in the the S-wave. The rho(770) is observed dominantly in the P0-wave and the f2(1270) is observed dominantly in the D0-wave. In addition, there is evidence for a broad enhancement in the D-wave below 1 GeV.Comment: 12 pages, Latex, 4 Figure
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