Electron Phonon Collisions, Fermi Dirac Distribution and Bloch's T5T^5 law

In this paper, we model exchange of energy between electrons in solids and the phonon bath as electron-phonon collisions. Phonons are modelled as packets which create a lattice deformation potential of which electrons scatter. We show how these collisions exchange energy between electrons and phonons, leading to Fermi-Dirac distribution for electrons. Using these collisions, we derive the temperature dependence of resistivity of metals and the Bloch's $T$ and $T^5$ law for high and low temperature regime respectively. Unlike standard derivations of $T$ dependence of high temperature resistivity, our derivation rests fundamentally on the temperature dependence of the scattering angle.Comment: 14 pages, 10 Figures. arXiv admin note: text overlap with arXiv:1710.0348

Reforming institutions for service delivery : a framework for development assistance with an application to the health, nutrition, and population portfolio

World Development Report 1997: The State in a Changing World (report no. 17300) argued that institutions-the rules of the game that govern production and exchange-shape a country's prospects for sustained market-led growth. The author provides an institutional framework for service delivery, an essential component of state capability. He applies this framework to an evaluation of Bank support for service delivery in the health, nutrition, and population sector. He argues for greater institutional pluralism in the ways the World Bank does business in infrastructure, rural, and social sectors, but cautions against making efficient service delivery an issue of"state versus market."The Bank and its clients face the challenge of fitting menus of"better practice"delivery options to maps of institutional reality. In the health, nutrition, and population sector, the Bank should (1) unbundle and categorize essential health and clinical services according to goods characteristics and (2) integrate country knowledge into operations through upstream assessments of state, political, and social institutions. Overall, the Bank has made progress toward a"goods characteristics"approach, particularly in infrastructure and some rural services-but it has lagged in the social sectors, where support remains largely technocratic. Cross-sector comparisons reveal four generations of support for service delivery. First-generation support focused mainly on physical implementation of projects. Second-generation interventions, which characterized most social service interventions, focused on improving the financial and organizational viability of implementing agencies through technical assistance. Third-generation support was marked by significant unbundling of service delivery activities and clearer links to goods characteristics. In irrigation (1982-94), telecommunications (1980s-present), and transport (1990s), the one-size-fits-all monopoly model gave way to a range of options based on greater private sector and citizen participation in delivery. These included leases, concessions, outsourcing, and contracting as well as building, operating, transfer, and turnover schemes. Fourth-generation interventions are works-in-progress and represent efforts to develop new governance arrangements that systematically combine competition, voice, and hierarchy in the design, delivery, and monitoring of Bank projects. The Bank has a poor track record building country knowledge of institutional endowments that affect service delivery. The author identifies concepts and tools valuable for sector specialists'operations.Enterprise Development&Reform,Public Health Promotion,Health Economics&Finance,Decentralization,Health Monitoring&Evaluation,Governance Indicators,Poverty Assessment,Environmental Economics&Policies,Health Monitoring&Evaluation,Health Economics&Finance

Adiabaticity and the Fate of Non-Gaussianities: The Trispectrum and Beyond

Extending the analysis of [1011.4934] beyond the bispectrum, we explore the superhorizon generation of local non-gaussianities and their subsequent approach to adiabaticity. Working with a class of two field models of inflation with potentials amenable to treatment with the delta N formalism we find that, as is the case for f_{NL}^{local}, the local trispectrum parameters tau_{NL} and g_{NL} are exponentially driven toward values which are slow roll suppressed if the fluctuations are driven into an adiabatic mode by a phase of effectively single field inflation. We argue that general considerations should ensure that a similar behavior will hold for the local forms of higher point correlations as well.Comment: v3: Updated to match published version, minor corrections throughout, 17 pages; v2: Corrected counting of higher order non-linearity parameters, added references, updated formatting, conclusions unchanged, 16 pages; v1: 16 page

Phase diagram of mechanically stretched DNA: The salt effect

The cations, in form of salt, present in the solution containing DNA play a crucial role in the opening of two strands of DNA. We use a simple non linear model and investigate the role of these cations on the mechanical unzipping of DNA. The Hamiltonian is modified to incoporate the solvent effect and the cations present in the solution. We calculate the melting temperature as well as the critical force that is required to unzip the DNA molecule as a function of salt concentration of the solution. The phase diagrams are found to be in close agreement with the experimental phase diagrams