974 resultados para 100-250 µm
Resumo:
Parkinson's disease (PD) is associated with enhanced synchronization of neuronal network activity in the beta (15-30 Hz) frequency band across several nuclei of the basal ganglia (BG). Deep brain stimulation of the subthalamic nucleus (STN) appears to reduce this pathological oscillation, thereby alleviating PD symptoms. However, direct stimulation of primary motor cortex (M1) has recently been shown to be effective in reducing symptoms in PD, suggesting a role for cortex in patterning pathological rhythms. Here, we examine the properties of M1 network oscillations in coronal slices taken from rat brain. Oscillations in the high beta frequency range (layer 5, 27.8 +/- 1.1 Hz, n=6) were elicited by co-application of the glutamate receptor agonist kainic acid (400 nM) and muscarinic receptor agonist carbachol (50 mu M). Dual extracellular recordings, local application of tetrodotoxin and recordings in M1 micro-sections indicate that the activity originates within deep layers V/VI. Beta oscillations were unaffected by specific AMPA receptor blockade, abolished by the GABA type A receptor (GABAAR) antagonist picrotoxin and the gap-junction blocker carbenoxolone, and modulated by pentobarbital and zolpidem indicating dependence on networks of GABAergic interneurons and electrical coupling. High frequency stimulation (HFS) at 125 Hz in superficial layers, designed to mimic transdural/transcranial stimulation, generated gamma oscillations in layers 11 and V (incidence 95%, 69.2 +/- 7.3 Hz, n=17) with very fast oscillatory components (VFO; 100-250 Hz). Stimulation at 4 Hz, however, preferentially promoted theta activity (incidence 62.5%, 5.1 +/- 0.6 Hz, n=15) that effected strong amplitude modulation of ongoing beta activity. Stimulation at 20 Hz evoked mixed theta and gamma responses. These data suggest that within M1, evoked theta, gamma and fast oscillations may coexist with and in some cases modulate pharmacologically induced beta oscillations.
Resumo:
Two high-resolution sediment cores from eastern Fram Strait have been investigated for sea subsurface and surface temperature variability during the Holocene (the past ca 12,000 years). The transfer function developed by Husum and Hald (2012) has been applied to sediment cores in order to reconstruct fluctuations of sea subsurface temperatures throughout the period. Additional biomarker and foraminiferal proxy data are used to elucidate variability between surface and subsurface water mass conditions, and to conclude on the Holocene climate and oceanographic variability on the West Spitsbergen continental margin. Results consistently reveal warm sea surface to subsurface temperatures of up to 6 °C until ca 5 cal ka BP, with maximum seawater temperatures around 10 cal ka BP, likely related to maximum July insolation occurring at that time. Maximum Atlantic Water (AW) advection occurred at surface and subsurface between 10.6 and 8.5 cal ka BP based on both foraminiferal and dinocyst temperature reconstructions. Probably, a less-stratified, ice-free, nutrient-rich surface ocean with strong AW advection prevailed in the eastern Fram Strait between 10 and 9 cal ka BP. Weakened AW contribution is found after ca 5 cal ka BP when subsurface temperatures strongly decrease with minimum values between ca 4 and 3 cal ka BP. Cold late Holocene conditions are furthermore supported by high planktic foraminifer shell fragmentation and high d18O values of the subpolar planktic foraminifer species Turborotalita quinqueloba. While IP25-associated indices as well as dinocyst data suggest a sustained cooling due to a decrease in early summer insolation and consequently sea-ice increase since about 7 cal ka BP in surface waters, planktic foraminiferal data including stable isotopes indicate a slight return of stronger subsurface AW influx since ca 3 cal ka BP. The observed decoupling of surface and subsurface waters during the later Holocene is most likely attributed to a strong pycnocline layer separating cold sea-ice fed surface waters from enhanced subsurface AW advection. This may be related to changes in North Atlantic subpolar versus subtropical gyre activity.
Resumo:
The Arctic is responding more rapidly to global warming than most other areas on our planet. Northward flowing Atlantic Water is the major means of heat advection towards the Arctic and strongly affects the sea ice distribution. Records of its natural variability are critical for the understanding of feedback mechanisms and the future of the Arctic climate system, but continuous historical records reach back only ~150 years. Here, we present a multidecadal scale record of ocean temperature variations during the last 2000 years, derived from marine sediments off Western Svalbard (79°N). We find that early-21st-century temperatures of Atlantic Water entering the Arctic Ocean are unprecedented over the past 2000 years and are presumably linked to the Arctic Amplification of global warming.
Resumo:
Two single-dose regimens of ciprofloxacin, 100 and 250 mg, were compared in the treatment of uncomplicated urinary tract infections in women. Cure rates 5 days after therapy did not significantly differ, being 16 of 19 (84%) with the 100-mg dose and 17 of 19 (89%) with the 250-mg dose. Ciprofloxacin was well tolerated.
Resumo:
Proyecto de una dinamo de inducido dentado e inductor multipolar en derivación, de 100 kv de potencia y de una diferencia de potencial en las terminales de 250 V.
Resumo:
"July 1972."
Resumo:
"June 1972."
Resumo:
Includes indexes.
Resumo:
Shipping list no.: 88-684-P.
Resumo:
Includes index.
Resumo:
Includes index.
Resumo:
INTRODUÇÃO: O Grupo de Qualidade de Vida da OMS desenvolveu um instrumento de avaliação de Qualidade de Vida, o WHOQOL-100 que está traduzido para 20 idiomas (WHOQOL GROUP, 1998). A aplicação do instrumento na versão em português é o objetivo do trabalho. MÉTODOS: Foram aplicados em 250 pacientes provenientes de quatro grandes áreas médicas (psiquiatria, clínica, cirurgia e ginecologia) de um hospital de clínicas de Porto Alegre, RS, e em 50 voluntários-controles o Instrumento de Avaliação de Qualidade de Vida da OMS (WHOQOL-100), o Inventário de Beck para a depressão (BDI) e a Escala de Desesperança de Beck (BHS). RESULTADOS E CONCLUSÕES:O Instrumento mostrou bom desempenho psicométrico com características satisfatórias de consistência interna, validade discriminante, validade de critério, validade concorrente e fidedignidade teste-reteste. Concluiu-se que o instrumento está em condições de ser usado no Brasil, sendo importante avaliar seu desempenho em outras regiões e em diferentes amostras de indivíduos.