Close temporal coupling of neuronal activity and tissue oxygen responses in rodent whisker barrel cortex

Neuronal activity elicits metabolic and vascular responses, during which oxygen is first consumed and then supplied to the tissue via an increase in cerebral blood flow. Understanding the spatial and temporal dynamics of blood and tissue oxygen (To(2)) responses following neuronal activity is crucial for understanding the physiological basis of functional neuroimaging signals. However, our knowledge is limited because previous To(2) measurements have been made at low temporal resolution (>100 ms). Here we recorded To(2) at high temporal resolution (1 ms), simultaneously with co-localized field potentials, at several cortical depths from the whisker region of the somatosensory cortex in anaesthetized rats and mice. Stimulation of the whiskers produced rapid, laminar-specific changes in To(2). Positive To(2) responses (i.e. increases) were observed in the superficial layers within 50 ms of stimulus onset, faster than previously reported. Negative To(2) responses (i.e. decreases) were observed in the deeper layers, with maximal amplitude in layer IV, within 40 ms of stimulus onset. The amplitude of the negative, but not the positive, To(2) response correlated with local field potential amplitude. Disruption of neurovascular coupling, via nitric oxide synthase inhibition, abolished positive To(2) responses to whisker stimulation in the superficial layers and increased negative To(2) responses in all layers. Our data show that To(2) responses occur rapidly following neuronal activity and are laminar dependent

The development and field use of a snow collector for acid precipitation studies

SIGLEAvailable from British Library Document Supply Centre- DSC:7628.85(WSL-LR-585(PA)M) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Accelerator-driven sub-critical target concept for transmutation of nuclear wastes

A means of transmuting key long-lived nuclear wastes, primarily the minor actinides (Np, Am, Cm) and iodine, using a hybrid proton accelerator and sub-critical lattice, is proposed. By partitioning the components of the light water reactor (LWR) spent fuel and by transmuting key elements, such as the plutonium, the minor actinides, and a few of the long-lived fission products, some of the most significant challenges in building a waste repository can be substantially reduced. The proposed machine, based on the described PHOENIX Concept, would transmute the minor actinides and the iodine produced by 75 LWRs, and would generate usable electricity (beyond that required to run the large accelerator) of 850 MW{sub e}. 19 refs., 20 figs

Impact of ICT-enabled product and process innovations at the Bottom of the Pyramid:a market separations approach

Innovations in products and processes enabled by ICT such as mobile phones and the Internet constitute a rapidly emerging means of market development at the Bottom of the Pyramid (BOP), which consists of people who earn less than US$2 a day. However, these ICT-enabled market development efforts have not always yielded positive developmental outcomes, in part because market development is hindered by remote location and geographic dispersion of BOP communities, their low and uncertain incomes, and informal local markets having exploitative intermediaries. These conditions imply that BOP consumers and producers are ‘separated’ from marketers and customers, respectively, through physical distance, lack of financial ability, and information asymmetry. The paper examines the question: How do ICT innovations in products and processes impact development at the BOP? Drawing perspectives from the information systems (IS) and marketing literatures, we analyze how and why ICT-enabled innovations in products and processes deployed for market development at the BOP, enable developmental outcomes through reduction of market separations. Analyzing qualitative data gathered from interviews with 33 respondents in India, including BOP individuals, social entrepreneurs, and managers from private organizations, we find that ICT-enabled product and process innovations do have the potential to reduce four types of separations that ‘disconnect’ BOP consumers (producers) from marketers (customers). However, situated social conditions influence the impact of ICT innovations on reduction of separations. The reduction of separations leads to developmental outcomes at the BOP. Implications of our findings for theory, practice, and policy are discussed

Indigenous Traces in Colonial Spaces: Archaeologies of Ambiguity, Origins, and Practices

This article reconsiders how archaeologists find Indigenous people, particularly Native Americans, in past colonial communities. Significant progress has been made in studying indigenous living areas associated with colonial communities but not in recovering evidence for (or even remembering) Native people laboring in distinctly colonial spaces. I propose that the reason for the lag lies in an incomplete perspective on material culture and space that denies their polyvalent and ambiguous, yet informative and manifestly real, nature. A new perspective can be forged with greater use of social theory pertaining to practice, space, and labor. Reconceptualizing material culture and space in colonial contexts requires that archaeologists acknowledge the role of labor relations in structuring material and spatial practices and not conflate origins of artifacts and spaces with other possible social meanings derived from practice. This article examines these two dimensions with three North American cases from New England, Florida, and California