Acculturation of the Spanish speaking people of Fort Collins, Colorado, in selected culture areas, The

August, 1947.Includes bibliographical references (pages 150-153)

Sistemas Hipertexto & Hipermédia - Reflexão, Ensino e Arte

Neste artigo começa por caracterizar-se o desenvolvimento dos sistemas hiper-texto/hipermédia associado ao paradigma da representação mental. Procura-se analisar o fundamento da atitude de mimésis entre os referidos sistemas e as representações internas do indivíduo no processamento de informação. Seguidamente, destaca-se o papel das tecnologias hipertexto/hipermédia no sistema educativo e o impacto inerente à sua implementação. Inclui, no final, uma reflexão sobre a cultura hipertexto/hipermédia e as suas repercussões no mundo da arte

A history of the Mexican-American people /

Includes bibliographies and index

Neurovascular coupling is not influenced by lower body negative pressure in humans

Cerebral blood flow is tightly coupled with local neuronal activation and metabolism, i.e., neurovascular coupling (NVC). Studies suggest a role of sympathetic nervous system in the regulation of cerebral blood flow. However, this is controversial, and the sympathetic regulation of NVC in humans remains unclear. Since impaired NVC has been identified in several chronic diseases associated with a heightened sympathetic activity, we aimed to determine whether reflex-mediated sympathetic activation via lower body negative pressure (LBNP) attenuates NVC in humans. NVC was assessed using a visual stimulation protocol (5 cycles of 30 s eyes closed and 30 s of reading) in 11 healthy participants (aged 24 ± 3 yr). NVC assessments were made under control conditions and during LBNP at -20 and -40 mmHg. Posterior (PCA) and middle (MCA) cerebral artery mean blood velocity (Vmean) and vertebral artery blood flow (VAflow) were simultaneously determined with cardiorespiratory variables. Under control conditions, the visual stimulation evoked a robust increase in PCAVmean (∆18.0 ± 4.5%), a moderate rise in VAflow (∆9.6 ± 4.3%), and a modest increase in MCAVmean (∆3.0 ± 1.9%). The magnitude of NVC response was not affected by mild-to-moderate LBNP (all P > 0.05 for repeated-measures ANOVA). Given the small change that occurred in partial pressure of end-tidal CO2 during LBNP, this hypocapnia condition was matched via voluntary hyperventilation in absence of LBNP in a subgroup of participants (n=8). The mild hypocapnia during LBNP did not exert a confounding influence on the NVC response. These findings indicate that the NVC is not influenced by LBNP or mild hypocapnia in humans