Paying the forest for electricity: A modelling framework to market forest conservation as payment for ecosystem services benefiting hydropower generation

Published in PESC Special issue: Payments for ecosystem services in conservation: performance and prospectsThe operation and longevity of hydropower dams are often negatively impacted by sedimentation. Forest conservation can reduce soil erosion, and therefore efforts to maintain upstream forest cover within a watershed contribute to the economic life span of a hydropower facility. The cost of forest conservation can be viewed as an investment in hydropower and be financed via a payment for ecosystem services (PES) scheme. A novel modelling framework is used to estimate payments for forest conservation consisting of: (1) land-use change projection; (2)watershed erosion modelling; (3) reservoir sedimentation estimation; (4) power generation loss calculation; and (5) PES scheme design. The framework was applied to a proposed dam in Cambodia (Pursat 1). The estimated net present value of forest conservation was US$4.7 million when using average annual climate values over 100 years, or US$ 6.4 million when considering droughts every eight years. This can be remunerated with annual payments ofUS$4.26ha-1 or US$ 5.78ha-1, respectively, covering forest protection costs estimated at US$ 0.9 ha-1 yr-1. The application of this type of PES represents a rational option that allows for conservation and development of hydropower watersheds susceptible to erosion and sedimentation

Paying the forest for electricity: A modelling framework to market forest conservation as payment for ecosystem services benefiting hydropower generation

Published in PESC Special issue: Payments for ecosystem services in conservation: performance and prospectsThe operation and longevity of hydropower dams are often negatively impacted by sedimentation. Forest conservation can reduce soil erosion, and therefore efforts to maintain upstream forest cover within a watershed contribute to the economic life span of a hydropower facility. The cost of forest conservation can be viewed as an investment in hydropower and be financed via a payment for ecosystem services (PES) scheme. A novel modelling framework is used to estimate payments for forest conservation consisting of: (1) land-use change projection; (2)watershed erosion modelling; (3) reservoir sedimentation estimation; (4) power generation loss calculation; and (5) PES scheme design. The framework was applied to a proposed dam in Cambodia (Pursat 1). The estimated net present value of forest conservation was US$4.7 million when using average annual climate values over 100 years, or US$ 6.4 million when considering droughts every eight years. This can be remunerated with annual payments ofUS$4.26ha-1 or US$ 5.78ha-1, respectively, covering forest protection costs estimated at US$ 0.9 ha-1 yr-1. The application of this type of PES represents a rational option that allows for conservation and development of hydropower watersheds susceptible to erosion and sedimentation

Accurate hyperfine couplings for C59N

We identify the shortcomings of existing ab initio quantum chemistry calculations for the hyperfine couplings in the recently characterized azafullerene, C59N. Standard gaussian basis sets in the context of all--electron calculations are insufficient to resolve the spin density near the cores of the atoms. Using the Projector Augmented Wave method implemented on top of a standard pseudopotential plane--wave density--functional framework, we compute significantly more accurate values for the Fermi contact interaction.Comment: 8 pages, 4 figure

Multiscale Computation with Interpolating Wavelets

Multiresolution analyses based upon interpolets, interpolating scaling functions introduced by Deslauriers and Dubuc, are particularly well-suited to physical applications because they allow exact recovery of the multiresolution representation of a function from its sample values on a finite set of points in space. We present a detailed study of the application of wavelet concepts to physical problems expressed in such bases. The manuscript describes algorithms for the associated transforms which, for properly constructed grids of variable resolution, compute correctly without having to introduce extra grid points. We demonstrate that for the application of local homogeneous operators in such bases, the non-standard multiply of Beylkin, Coifman and Rokhlin also proceeds exactly for inhomogeneous grids of appropriate form. To obtain less stringent conditions on the grids, we generalize the non-standard multiply so that communication may proceed between non-adjacent levels. The manuscript concludes with timing comparisons against naive algorithms and an illustration of the scale-independence of the convergence rate of the conjugate gradient solution of Poisson's equation using a simple preconditioning, suggesting that this approach leads to an O(n) solution of this equation.Comment: 33 pages, figures available at http://laisla.mit.edu/muchomas/Papers/nonstand-figs.ps . Updated: (1) figures file (figs.ps) now appear with the posting on the server; (2) references got lost in the last submissio

Ab initio and finite-temperature molecular dynamics studies of lattice resistance in tantalum

This manuscript explores the apparent discrepancy between experimental data and theoretical calculations of the lattice resistance of bcc tantalum. We present the first results for the temperature dependence of the Peierls stress in this system and the first ab initio calculation of the zero-temperature Peierls stress to employ periodic boundary conditions, which are those best suited to the study of metallic systems at the electron-structure level. Our ab initio value for the Peierls stress is over five times larger than current extrapolations of experimental lattice resistance to zero-temperature. Although we do find that the common techniques for such extrapolation indeed tend to underestimate the zero-temperature limit, the amount of the underestimation which we observe is only 10-20%, leaving open the possibility that mechanisms other than the simple Peierls stress are important in controlling the process of low temperature slip.Comment: 12 pages and 9 figure

Simulating Physical Phenomena by Quantum Networks

Physical systems, characterized by an ensemble of interacting elementary constituents, can be represented and studied by different algebras of observables or operators. For example, a fully polarized electronic system can be investigated by means of the algebra generated by the usual fermionic creation and annihilation operators, or by using the algebra of Pauli (spin-1/2) operators. The correspondence between the two algebras is given by the Jordan-Wigner isomorphism. As we previously noted similar one-to-one mappings enable one to represent any physical system in a quantum computer. In this paper we evolve and exploit this fundamental concept in quantum information processing to simulate generic physical phenomena by quantum networks. We give quantum circuits useful for the efficient evaluation of the physical properties (e.g, spectrum of observables or relevant correlation functions) of an arbitrary system with Hamiltonian $H$.Comment: 44 pages, 15 psfigur

Acceleration Schemes for Ab-Initio Molecular Dynamics and Electronic Structure Calculations

We study the convergence and the stability of fictitious dynamical methods for electrons. First, we show that a particular damped second-order dynamics has a much faster rate of convergence to the ground-state than first-order steepest descent algorithms while retaining their numerical cost per time step. Our damped dynamics has efficiency comparable to that of conjugate gradient methods in typical electronic minimization problems. Then, we analyse the factors that limit the size of the integration time step in approaches based on plane-wave expansions. The maximum allowed time step is dictated by the highest frequency components of the fictitious electronic dynamics. These can result either from the large wavevector components of the kinetic energy or from the small wavevector components of the Coulomb potential giving rise to the so called {\it charge sloshing} problem. We show how to eliminate large wavevector instabilities by adopting a preconditioning scheme that is implemented here for the first-time in the context of Car-Parrinello ab-initio molecular dynamics simulations of the ionic motion. We also show how to solve the charge-sloshing problem when this is present. We substantiate our theoretical analysis with numerical tests on a number of different silicon and carbon systems having both insulating and metallic character.Comment: RevTex, 9 figures available upon request, to appear in Phys. Rev.

Non-Equilibrium Electron Transport in Two-Dimensional Nano-Structures Modeled by Green's Functions and the Finite-Element Method

We use the effective-mass approximation and the density-functional theory with the local-density approximation for modeling two-dimensional nano-structures connected phase-coherently to two infinite leads. Using the non-equilibrium Green's function method the electron density and the current are calculated under a bias voltage. The problem of solving for the Green's functions numerically is formulated using the finite-element method (FEM). The Green's functions have non-reflecting open boundary conditions to take care of the infinite size of the system. We show how these boundary conditions are formulated in the FEM. The scheme is tested by calculating transmission probabilities for simple model potentials. The potential of the scheme is demonstrated by determining non-linear current-voltage behaviors of resonant tunneling structures.Comment: 13 pages,15 figure

FGF receptor genes and breast cancer susceptibility: results from the Breast Cancer Association Consortium

Background:Breast cancer is one of the most common malignancies in women. Genome-wide association studies have identified FGFR2 as a breast cancer susceptibility gene. Common variation in other fibroblast growth factor (FGF) receptors might also modify risk. We tested this hypothesis by studying genotyped single-nucleotide polymorphisms (SNPs) and imputed SNPs in FGFR1, FGFR3, FGFR4 and FGFRL1 in the Breast Cancer Association Consortium. Methods:Data were combined from 49 studies, including 53 835 cases and 50 156 controls, of which 89 050 (46 450 cases and 42 600 controls) were of European ancestry, 12 893 (6269 cases and 6624 controls) of Asian and 2048 (1116 cases and 932 controls) of African ancestry. Associations with risk of breast cancer, overall and by disease sub-type, were assessed using unconditional logistic regression. Results:Little evidence of association with breast cancer risk was observed for SNPs in the FGF receptor genes. The strongest evidence in European women was for rs743682 in FGFR3; the estimated per-allele odds ratio was 1.05 (95 confidence interval=1.02-1.09, P=0.0020), which is substantially lower than that observed for SNPs in FGFR2. Conclusion:Our results suggest that common variants in the other FGF receptors are not associated with risk of breast cancer to the degree observed for FGFR2. © 2014 Cancer Research UK

The methodological quality is insufficient in clinical practice guidelines in the context of COVID-19 : systematic review

Objectives The number of published clinical practice guidelines related to COVID-19 has rapidly increased. This study explored if basic methodological standards of guideline development have been met in the published clinical practice guidelines related to COVID-19. Study Design and Setting Rapid systematic review from February 1 until April 27, 2020 using MEDLINE [PubMed], CINAHL [Ebsco], Trip and manual search, including all types of healthcare workers providing any kind of healthcare to any patient population in any setting. Results There were 1342 titles screened and 188 guidelines included. The highest average AGREE II domain score was 89% for scope and purpose, the lowest for rigor of development (25%). Only eight guidelines (4%) were based on a systematic literature search and a structured consensus process by representative experts (classified as the highest methodological quality). The majority (156; 83%) was solely built on an informal expert consensus. A process for regular updates was described in 27 guidelines (14%). Patients were included in the development of only one guideline. Conclusion Despite clear scope, most publications fell short of basic methodological standards of guideline development. Clinicians should use guidelines that include up-to-date information, were informed by stakeholder involvement, and employed rigorous methodologies