University of New Hampshire

About: University of New Hampshire is a education organization based out in Durham, New Hampshire, United States. It is known for research contribution in the topics: Population & Solar wind. The organization has 9379 authors who have published 24025 publications receiving 1020112 citations. The organization is also known as: UNH.

The Turbulent Cascade at 1 AU: Energy Transfer and the Third-Order Scaling for MHD

Abstract: We perform a test of MHD turbulent cascade theory in the solar wind and directly evaluate the contribution of local turbulence to heating the solar wind at 1 AU. We look at turbulent fluctuations in the solar wind velocity V and magnetic field B, using the vector Elsasser variables Z ± ≡ V ± B/(4πρ)1/2 as measured at the ACE spacecraft stationed at the Earth's L1 point. We combine the fluctuations δZ± over time lags in the inertial range, from 64 s to several hours, to form components of the mixed vector third moments, and we adopt the work of Politano & Pouquet, who derive an exact scaling law, similar to the Kolmogorov 4/5 law, but valid in anisotropic MHD turbulence, for these components. We demonstrate that the scaling is reasonably linear, as is expected for the inertial range. The total turbulent energy injection/dissipation rate that we derive this way agrees with the in situ heating of the solar wind that is inferred from the temperature gradient, whereas methods using the power spectra only seldom agree with the heating rates derived from gradients of the thermal proton distribution. We derive expressions of the third-order moments that are applicable to the spectral cascades parallel and perpendicular to the mean magnetic field. We apply these expressions to fast- and slow-wind subsets of the data, with additional subsetting for mean field direction. We find that both the fast wind and the slow wind exhibit an active energy cascade over the inertial range scales. Furthermore, we find that the energy flux in the parallel cascade is consistently smaller than in the perpendicular cascade.

Primary production and abiotic controls in forests, grasslands, and desert ecosystems in the united states'

Abstract: This paper, a synthesis based on data generated by the International Biological Pro- gram, deals with the relationships among biotic and abiotic factors at the ecosystem level. Emphasis is placed on aboveground net primary production (ANPP), a major component of energy that drives ecosystem processes, and on potential evapotranspiration (PET), the abiotic variable most often used to explain variation in ANPP. The question addressed is: can ANPP be related to combinations of biotic and abiotic factors such that the relationships are independent of ecosystem type, whether it be forest, grassland, or desert'? ANPP as a function of peak foliar standing crop (FSC) was best explained by models which showed a reduction in ANPP/FSC as FSC increased. Thus, deserts had a higher ANPP per unit of FSC than did other systems. As expected, photosynthetic efficiency (PE) was highest for forests, -ZOO times greater than for deserts. However, when PE was evaluated per unit of foliage, the differences in PE of ecosystems were much less. In fact, a hot-desert site had the highest PE/FSC. In terms of a theoretical maximum, the PE of forests was only 6-25% of the maximum value. Systems with nearly steady-state aboveground standing crop (ASC) showed an exponential decrease with decreased water availability (potential evapotranspiration minus precipitation). For these same systems, the ratio of ANPP to ASC increased with decreased water availability, suggesting that water-stressed systems need more energy from ANPP to drive internal processes. A model predicting ANPP of desert-shortgrass steppes was structured in terms of FSC, water availability, and temperature. The predictive power was found to be very highs and the model was successfully validated in two of three cases with an independent data set. A model predicting ANPP of forests was structured in terms of FSC, radiation, ASC, and temperature. The deviation of the observed ANPP relative to that calculated was 17%. Deviations from predicted values were highest for deciduous stands with high ANPP and low FSC. Most relationships exhibited good correlations between ANPP and the various independent vari- ables including both biotic, abiotic, and combinations of the two. However, in many instances the data tended to be grouped by ecosystem type, suggesting that variation in ANPP can be reduced if ecosystem type is an added independent variable. It was surprising to find that, with the limits of our data, differences in ANPP at the ecosystem level are not glaring, especially considering that soil factors were not included in our analyses. When considering the broad range of genotypes in each ecosystem, and the much broader genotypic range representing all ecosystems, the control that native ecosystems have over abiotic factors in producing ANPP is evident but not large.

Identifying Firm Capabilities as Drivers of Environmental Management and Sustainability Practices – Evidence from Small and Medium-Sized Manufacturers

Abstract: Firms increasingly need to consider environmental issues as a result of stricter governmental regulation and due to growing pressures from a broad range of stakeholders. The literature on environmental management is vast but not much is known about firm-specific capabilities that facilitate the adoption of environmental practices and environmental collaboration. Drawing on the dynamic capabilities literature, this study identifies the adoption of advanced technology, experiences with inter-firm relations and capacity for product innovation as three capabilities that support firms' efforts to become ‘greener’. Descriptive statistics portray the diffusion of the related management practices among 294 small and medium-sized manufacturers from the United States. Based on regression analysis, the authors provide evidence for a relationship between the underlying capabilities and environmental management practices. Consequently, the results point to additional benefits of known strategic capabilities and suggest how firms should approach sustainability initiatives by developing certain competencies first. Copyright © 2012 John Wiley & Sons, Ltd and ERP Environment.

Prewhitening Bias in HAC Estimation

Abstract: Later version now published as a Journal Article: Oxford Bulletin of Economics & Statistics 67 (4), 517-546. doi: 10.1111/j.1468-0084.2005.00130.x