Fermi Liquid Properties of a Two Dimensional Electron System With the Fermi Level Near a van Hove Singularity

We use a diagrammatic approach to study low energy physics of a two dimensional electron system where the Fermi level is near van-Hove singularies in the energy spectrum. We find that in most regions of the $\epsilon_F-T$ phase diagram the system behaves as a normal Fermi liquid rather than a marginal Fermi liquid. Particularly, the imaginary part of the self energy is much smaller than the excitation energy, which implies well defined quasiparticle excitations, and single particle properties are only weakly affected by the presence of the van-Hove singularities. The relevance to high temperature superconductivity is also discussed.Comment: 10 pages, 4 postscript figure

1898: The Start of American Imperialism, or its End?

The year 1898, with the annexation of Hawaii and the results of Spanish-American War – namely the acquisition of more overseas territory – has traditionally served as the benchmark for what would be known as ‘American Imperialism’. At the time, and in the 117 years since, very little material has been produced which questions either the nature of ‘American Imperialism’ or its assumed start date. This paper seeks to accomplish exactly those aims. By first exploring the historiography of the broader nature of ‘imperialism’, then seeing how the ‘American System’ adapted and applied it, I will use specific case-study examples to test the hypothesis that rather than beginning in 1898, ‘American Imperialism’ actually ended in that year, and has not been a policy or practice of the United States since

Recommendations for Implementing Hepatitis C Virus Care in Homeless Shelters: The Stakeholder Perspective.

Compared with the general population, homeless individuals are at higher risk of hepatitis C infection (HCV) and may face unique barriers in receipt of HCV care. This study sought the perspectives of key stakeholders toward establishing a universal HCV screening, testing, and treatment protocol for individuals accessing homeless shelters. Four focus groups were conducted with homeless shelter staff, practice providers, and social service outreach workers (n = 27) in San Francisco, California, and Minneapolis, Minnesota. Focus groups evaluated key societal, system, and individual-level facilitators and barriers to HCV testing and management. Interviews were transcribed and analyzed thematically. The societal-level barriers identified were lack of insurance, high-out-of-pocket expenses, restriction of access to HCV treatment due to active drug and/or alcohol use, and excessive paperwork required for HCV treatment authorization from payers. System-level barriers included workforce constraints and limited health care infrastructure, HCV stigma, low knowledge of HCV treatment, and existing shelter policies. At the individual level, client barriers included competing priorities, behavioral health concerns, and health attitudes. Facilitators at the system level for HCV care service integration in the shelter setting included high acceptability and buy in, and linkage with social service providers. Conclusion: Despite societal, system, and individual-level barriers identified with respect to the scale-up of HCV services in homeless shelters, there was broad support from key stakeholders for increasing capacity for the provision of HCV services in shelter settings. Recommendations for the scale-up of HCV services in homeless shelter settings are discussed

Youth in modern world

Today’s time may be also named as a time for bold measures. Franklin D. Roosevelt said: “We cannot always build the future for our youth, but we can build our youth for the future” [1]. Youth is often considered to represent the future as they bring new ideas and energy to add to the pool of knowledge that currently exists. They can bring enthusiasm and vitality which can lead to new discoveries and developments that can benefit society or even the world at large. Although not the only drivers of social change, young people are seen to be one the key drivers engendering change. Youth are not only the leaders of tomorrow, but also the partners of today. Young people are social actors of change and progress. The new generation has many fine ideas of completing a task and has better leadership qualities. Youth also renews and refreshes the current status of the society including leadership, innovations, skills etc. Youngsters are expected to advance the current technology, education, politics and peace of the country. On the other hand, young people have also to maintain the culture together with all good values in the society. So, youth plays a great role in modern society