Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 23
Filtrar
1.
Geophys Res Lett ; 45(2): 578-584, 2018 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-29576666

RESUMO

We report Magnetospheric Multiscale observations of electron pressure gradient electric fields near a magnetic reconnection diffusion region using a new technique for extracting 7.5 ms electron moments from the Fast Plasma Investigation. We find that the deviation of the perpendicular electron bulk velocity from E × B drift in the interval where the out-of-plane current density is increasing can be explained by the diamagnetic drift. In the interval where the out-of-plane current is transitioning to in-plane current, the electron momentum equation is not satisfied at 7.5 ms resolution.

2.
J Geophys Res Space Phys ; 122(11): 10891-10909, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-29399431

RESUMO

During a magnetic storm on 23 June 2015, several very intense substorms took place, with signatures observed by multiple spacecraft including DMSP and Magnetospheric Multiscale (MMS). At the time of interest, DMSP F18 crossed inbound through a poleward expanding auroral bulge boundary at 23.5 h magnetic local time (MLT), while MMS was located duskward of 22 h MLT during an inward crossing of the expanding plasma sheet boundary. The two spacecraft observed a consistent set of signatures as they simultaneously crossed the reconnection separatrix layer during this very intense reconnection event. These include (1) energy dispersion of the energetic ions and electrons traveling earthward, accompanied with high electron energies in the vicinity of the separatrix; (2) energy dispersion of polar rain electrons, with a high-energy cutoff; and (3) intense inward convection of the magnetic field lines at the MMS location. The high temporal resolution measurements by MMS provide unprecedented observations of the outermost electron boundary layer. We discuss the relevance of the energy dispersion of the electrons, and their pitch angle distribution, to the spatial and temporal evolution of the boundary layer. The results indicate that the underlying magnetotail magnetic reconnection process was an intrinsically impulsive and the active X-line was located relatively close to the Earth, approximately at 16-18 RE.

3.
Geophys Res Lett ; 43(10): 4841-4849, 2016 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-27867235

RESUMO

We report on field-aligned current observations by the four Magnetospheric Multiscale (MMS) spacecraft near the plasma sheet boundary layer (PSBL) during two major substorms on 23 June 2015. Small-scale field-aligned currents were found embedded in fluctuating PSBL flux tubes near the separatrix region. We resolve, for the first time, short-lived earthward (downward) intense field-aligned current sheets with thicknesses of a few tens of kilometers, which are well below the ion scale, on flux tubes moving equatorward/earthward during outward plasma sheet expansion. They coincide with upward field-aligned electron beams with energies of a few hundred eV. These electrons are most likely due to acceleration associated with a reconnection jet or high-energy ion beam-produced disturbances. The observations highlight coupling of multiscale processes in PSBL as a consequence of magnetotail reconnection.

4.
J Sci Med Sport ; 7(1): 1-10, 2004 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15139159

RESUMO

The purpose of this study was to compare the effectiveness of three different recovery modalities--active (ACT), passive (PAS) and contrast temperature water immersion (CTW)--on the performance of repeated treadmill running, lactate concentration and pH. Fourteen males performed two pairs of treadmill runs to exhaustion at 120% and 90% of peak running speed (PRS) over a 4-hour period. ACT, PAS or CTW was performed for 15-min after the first pair of treadmill runs. ACT consisted of running at 40% PRS, PAS consisted of standing stationary and CTW consisted of alternating between 60-s cold (10 degrees C) and 120-s hot (42 degrees C) water immersion. Run times were converted to time to cover set distance using critical power. Type of recovery modality did not have a significant effect on change in time to cover 400 m (Mean +/- SD; ACT 2.7 +/- 3.6 s, PAS 2.9 +/- 4.2 s, CTW 4.2 +/- 6.9 s), 1000 m (ACT 2.2 +/- 4.0 s, PAS 4.8 +/- 8.6 s, CTW 2.1 +/- 7.2 s) or 5000 m (ACT 1.4 +/- 29.0 s, PAS 16.7 +/- 58.5 s, CTW 11.7 +/- 33.0 s). Post exercise blood lactate concentration was lower in ACT and CTW compared with PAS. Participants reported an increased perception of recovery in the CTW compared with ACT and PAS. Blood pH was not significantly influenced by recovery modality. Data suggest both ACT and CTW reduce lactate accumulation after high intensity running, but high intensity treadmill running performance is returned to baseline 4-hours after the initial exercise bout regardless of the recovery strategy employed.


Assuntos
Tolerância ao Exercício/fisiologia , Exercício Físico/fisiologia , Fadiga Muscular/fisiologia , Corrida/fisiologia , Adulto , Estudos Cross-Over , Teste de Esforço , Humanos , Ácido Láctico/sangue , Masculino , Pessoa de Meia-Idade , Esportes , Temperatura , Fatores de Tempo , Água
6.
Br J Psychiatry ; 168(3): 368-71, 1996 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8833694

RESUMO

BACKGROUND: We investigated the hypothesis that prenatal exposure to the 1957 A2 influenza increases the risk of schizophrenia in adulthood. METHOD: We traced a cohort of individuals known to have been exposed to the 1957 influenza epidemic during gestation and an unexposed cohort matched for period of gestation and hospital of birth. Follow-up information on psychiatric illness in subjects was sought from two sources: maternal interview and psychiatric hospital admission data. RESULTS: Follow-up information was obtained on 54% of the sample: 238 subjects from the influenza-exposed group and 287 subjects from the unexposed group. There was no increased risk of schizophrenia among the exposed cohort compared to the unexposed cohort (relative risk 1.1; 95% Cl 0.41-2.95), although there was an increase in depressive illness (relative risk 1.59; 95% Cl 1.15-2.19). CONCLUSIONS: The association between prenatal influenza and an increased risk of schizophrenia in adulthood has thus far been found only in population-based data and is not supported by the present observational study which has information about exposure and outcome in individuals.


Assuntos
Surtos de Doenças , Influenza Humana/epidemiologia , Efeitos Tardios da Exposição Pré-Natal , Esquizofrenia/etiologia , Estudos de Coortes , Feminino , Seguimentos , Humanos , Incidência , Irlanda/epidemiologia , Gravidez , Cuidado Pré-Natal , Estudos Retrospectivos
15.
J Ir Dent Assoc ; 18(6): 248-54, 1972.
Artigo em Inglês | MEDLINE | ID: mdl-4510242
17.
Br Med J ; 4(5788): 682, 1971 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-5134577
18.
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA