Values of Ecosystem Services Associated with Intense Dairy Farming in New Zealand

The increase in greenhouse gas emissions and degradation of water quality and quantity in waterways due to dairy farming in New Zealand have become of growing concern. Compared to traditional sheep and beef cattle farming, dairy farming is more input intensive and more likely to cause such environmental damage. Our study uses choice modeling to explore New Zealanders' willingness to pay for sustainable dairy and sheep/beef cattle farming. We investigate respondents' level of awareness of the environmental degradation caused by dairy farming and their willingness to make trade-offs between economic growth and improvements in the level of ecosystem services associated with pastoral farming.ecosystem services, greenhouse gas emissions, dairy farming, choice modeling, Environmental Economics and Policy, Livestock Production/Industries,

Ecosystem Services on New Zealand Arable Farms

Researchers have estimated the total economic value of global ecosystem goods and services showing that a significant portion of humanity's economic well being is unaccounted for in conventional GNP accounting (Constanza et al., 1997). To demonstrate this point, authors have conventionally used highly aggregated landscape units for analysis (e.g., biomes), and average, not marginal values, of each ecosystem good or service are estimated for each unit using value transfer methodologies (Wilson et al., 2004). For example, Patterson and Cole (1999a, b) replicated the Constanza et al., (1997) approach by estimating economic values for Waikato and New Zealand ecosystem goods and services associated with standard land cover classes including horticulture, agriculture and cropping. As a result, Patterson and Cole (1999b) argue that only five ecosystem services associated with cropping have non-zero value. One of the reasons for this low number of non-zero values assorted with arable lands is that the original economic studies used by Patterson and Cole, are heavily weighted towards natural and undisturbed ecosystems rather than disturbed systems like agricultural or urban landscapes. To address this issue, more recently researchers have noted that many landscapes are actively modified by humans who seek to realise economic gain and this topic is thus an important one because in the 21st century, many of our homes, workplaces and recreational spaces are embedded within, or adjacent to, landscape mosaics that are to a greater or lesser degree affected by the conscious efforts of people to harness goods and services provided by ecological systems (Palmer et al., 2004). An engineered or designed ecosystem is one that has been extensively modified by humans to explicitly provide a set of ecosystem goods and services including more fresh water, trees, and food products and fewer floods and pollutants. These modified landscapes provide a range of ecosystem goods and services, particularly food production as farmers seek to maximize commercial gain from land use. The current paper examines issues in valuation of ecosystem goods and services derived from land used for arable farming in New Zealand and proposes ways to provide more detailed estimates of the flow and value of the flow of ecosystem services provided.Ecosystem management, Arable farming, Engineered ecosystem, Agricultural and Food Policy, Community/Rural/Urban Development, Crop Production/Industries, Environmental Economics and Policy, Farm Management, Land Economics/Use,

Macroscopic proof of the Jarzynski-Wojcik fluctuation theorem for heat exchange

In a recent work, Jarzynski and Wojcik (2004 Phys. Rev. Lett. 92, 230602) have shown by using the properties of Hamiltonian dynamics and a statistical mechanical consideration that, through contact, heat exchange between two systems initially prepared at different temperatures obeys a fluctuation theorem. Here, another proof is presented, in which only macroscopic thermodynamic quantities are employed. The detailed balance condition is found to play an essential role. As a result, the theorem is found to hold under very general conditions.Comment: 9 pages, 0 figure

Deuterium-deuterium nuclear cross-sections in insulator and metallic environments

The three-dimensional Thomas-Fermi (TF) model is used to simulate the variation of the d+d to t + p cross-section at low impact energies, when the target deuterium nucleus is embedded in metallic or insulator environments. Comparison of the computational results to recent experiments demonstrates that even though the TF model can explain some increase in the low energy cross section for metallic host, a full explanation of the experimental results is still lacking. Possible reasons for the disagreement are discussed.Comment: 6 pages;6 figures. Accepted for publication in Eur. Phys. Jour.

Fluctuation theorem for the renormalized entropy change in the strongly nonlinear nonequilibrium regime

Generalizing a recent work [T. Taniguchi and E. G. D. Cohen, J. Stat. Phys. 126, 1 (2006)] that was based on the Onsager-Machlup theory, a nonlinear relaxation process is considered for a macroscopic thermodynamic quantity. It is found that the fluctuation theorem holds in the nonlinear nonequilibrium regime if the change of the entropy characterized by local equilibria is appropriately renormalized. The fluctuation theorem for the ordinary entropy change is recovered in the linear near-equilibrium case. This result suggests a possibility that the the information-theoretic entropy of the Shannon form may be modified in the strongly nonlinear nonequilibrium regime.Comment: 14 pages, no figures. Typos correcte

Emptying Dirac valleys in bismuth using high magnetic fields

The Fermi surface of elemental bismuth consists of three small rotationally equivalent electron pockets, offering a valley degree of freedom to charge carriers. A relatively small magnetic field can confine electrons to their lowest Landau level. This is the quantum limit attained in other dilute metals upon application of sufficiently strong magnetic field. Here, we report on the observation of another threshold magnetic field never encountered before in any other solid. Above this field, $B_{\rm{empty}}$, one or two valleys become totally empty. Drying up a Fermi sea by magnetic field in the Brillouin zone leads to a manyfold enhancement in electric conductance. We trace the origin of the large drop in magnetoresistance across $B_{\rm{empty}}$ to transfer of carriers between valleys with highly anisotropic mobilities. The non-interacting picture of electrons with field-dependent mobility explains most results. Coulomb interaction may play a role in shaping the fine details.Comment: 19 pages, 5 figures, Supplemental Material available upon reques

Direct measurement of quantum phase gradients in superfluid 4He flow

We report a new kind of experiment in which we generate a known superfluid velocity in a straight tube and directly determine the phase difference across the tube's ends using a superfluid matter wave interferometer. By so doing, we quantitatively verify the relation between the superfluid velocity and the phase gradient of the condensate macroscopic wave function. Within the systematic error of the measurement (~10%) we find v_s=(hbar/m_4)*(grad phi)

A quantitative model for IcR product in d-wave Josephson junctions

We study theoretically the Josephson effect in d-wave superconductor / diffusive normal metal /insulator/ diffusive normal metal/ d-wave superconductor (D/DN/I/DN/D) junctions. This model is aimed to describe practical junctions in high-$T_C$ cuprate superconductors, in which the product of the critical Josephson current ($I_C$) and the normal state resistance ($R$) (the so-called $I_{\rm C}R$ product) is very small compared to the prediction of the standard theory. We show that the $I_{\rm C}R$ product in D/DN/I/DN/D junctions can be much smaller than that in d-wave superconductor / insulator / d-wave superconductor junctions and formulate the conditions necessary to achieve large $I_{\rm C}R$ product in D/DN/I/DN/D junctions. The proposed theory describes the behavior of $I_{\rm C}R$ products quantitatively in high-$T_{\rm C}$ cuprate junctions.Comment: 4 pages, 6 figure