Amperean pairing and the pseudogap phase of cuprate superconductors

The enigmatic pseudogap phase in underdoped cuprate high T_c superconductors has long been recognized as a central puzzle of the T_c problem. Recent data show that the pseudogap is likely a distinct phase, characterized by a medium range and quasi-static charge ordering. However, the origin of the ordering wavevector and the mechanism of the charge order is unknown. At the same time, earlier data show that precursive superconducting fluctuations are also associated with this phase. We propose that the pseudogap phase is a novel pairing state where electrons on the same side of the Fermi surface are paired, in strong contrast with conventional BCS theory which pair electrons on opposite sides of the Fermi surface. In this state the Cooper pair carries a net momentum and belong to a general class called pair density wave (PDW). The microscopic pairing mechanism comes from a gauge theory formulation of the resonating valence bond (RVB) picture, where electrons traveling in the same direction feel an attractive force in analogy with Ampere's effects in electromagnetism. We call this Amperean pairing. Charge order automatically appears as a subsidiary order parameter. Our theory gives a prediction of the ordering wavevector which is in good agreement with experiment. Furthermore, the quasiparticle spectrum from our model explains many of the unusual features reported in photoemission experiments. The Fermi arc and the unusual way the tip of the arc terminates also come out naturally. We also discuss how the onset of the Kerr effect in this state can be accommodated. Finally, we propose an experiment which can directly test the notion of Amperean pairing.Comment: (v4) added phase diagram, Appendix A on the incompatibility of CDW model, and more discussion of low-temperature properties; (v3) expanded supplementary section, added figures and discussion on Fermi arc; (v2) added references, improved figures, corrected typo in Eq.(4

Transatlantic Differences in Labour Markets: Changes in Wage and Non-Employment Structures in the 1980s and the 1990s

Rising wage inequality in the U.S. and Britain and rising continental European unemployment have led to a popular view in the economics profession that these two phenomena are related to negative relative demand shocks against the unskilled, combined with flexible wages in the Anglo-Saxon countries, but institutional rigidities in continental Europe ('Krugman hypothesis'). This paper tests this hypothesis based on seven large person-level data sets for the 1980s and the 1990s. I use a more sophisticated categorisation of low-skilled workers than previous studies, which highlights the distinction between German workers with and without apprenticeship training. I find evidence for the Krugman hypothesis when Germany is compared to the U.S. However, supply changes differ considerably between countries, with Britain experiencing enormous increases in skill supply explaining the relatively constant British skill premium in the 1990shttp://deepblue.lib.umich.edu/bitstream/2027.42/40148/3/wp762.pd

Stains Induce Apoptosis and Autophagy in Primary and Transformed Mast Cells

Statin drugs are widely employed in the clinic to reduce serum low density lipoproteins (LDLs) in patients with hypocholesteremia. In addition to their cholesterol-lowering effects through HMG CoA reductase antagonism, isoprenyl lipids necessary for membrane anchorage and signaling of small G-proteins are abrogated. We previously found that statins suppress mast cell activation in murine and human cells, suggesting these drugs might be useful in treating allergic disease. While mast cell function is critical to allergic inflammation, mast cell hyperplasia and survival also impact these diseases, and were not studied in our previous work. In this study, we describe Fluvastatin-mediated apoptosis in both primary and transformed mast cells. An IC50 was achieved between 1-5μM in both systems, and apoptosis was preceded by mitochondrial dysfunction and caspase release. In addition to apoptosis, our work also uncovered evidence of autophagy, which can serve as a compensatory mechanism during apoptosis. Interestingly, autophagy appeared to be cyto-protective in the primary cells yet cytotoxic in transformed mast cells. These findings offer insight into the mechanisms of mast cell survival and support the possible utility of statins in mast cell-associated allergic and neoplastic diseases

Labour mobility - an adjustment mechanism in Euroland? Empirical evidence for Western Germany, France and Italy

The purpose of this paper is to evaluate whether labour mobility is likely to act as a sufficient adjustment mechanism in the face of asymmetric shocks in Euroland. To this end, we estimate the elasticity of migration with respect to changes in unemployment and income on the basis of regional panel data provided by Eurostat, the statistical office of the European Union. Regression results are provided for Western Germany, France, and Italy. It is shown that labour mobility is highest in Germany, followed by France, and Italy. However, even in Germany, the accommodation of a shock to unemployment by migration takes several years. We conclude that labour mobility is extremely unlikely to act as a sufficient adjustment mechanism to asymmetric shocks in Euroland. --European Monetary Union (EMU),euro,labour mobility

What Happened to Wage and Non-Employment Structures During the ‘Dutch Employment Miracle’?

The Netherlands have experienced an employment miracle since the 1980s. This note investigates what happened to the wage, unemployment, and non-employment structures between 1988 and 1998, when both unemployment and non-employment rates decreased markedly. Surprisingly, I find no significant changes in the wage structures, although there clearly was wage moderation on average. Although there have also been virtually no changes in the unemployment structure, the relative non-employment of older workers (due to incentives to retire) and men increased. Whereas supply effects and early retirement schemes can explain the constancy of the returns to age, the lack of an increase in the returns to education remains a puzzle in the face of well-documented skill-biased technological change in other major industrialised countries.earnings, flexibility, labour

Professional identity

This chapter discusses the concept of professional identity and how professional teachers develop their identity. Policy contexts as well as research contexts are discussed in terms of how these shape professional working conditions

Transatlantic Differences in Labour Markets: Changes in Wage and Non-Employment Structures in the 1980s and the 1990s

Rising wage inequality in the U.S. and Britain and rising continental European unemployment have led to a popular view in the economics profession that these two phenomena are related to negative relative demand shocks against the unskilled, combined with flexible wages in the Anglo-Saxon countries, but institutional rigidities in continental Europe ('Krugman hypothesis'). This paper tests this hypothesis based on seven large person-level data sets for the 1980s and the 1990s. I use a more sophisticated categorisation of low-skilled workers than previous studies, which highlights the distinction between German workers with and without apprenticeship training. I find evidence for the Krugman hypothesis when Germany is compared to the U.S. However, supply changes differ considerably between countries, with Britain experiencing enormous increases in skill supply explaining the relatively constant British skill premium in the 1990swage, earnings, unemployment, non-employment, rigidity, identification

Advantage through training? A microeconometric evaluation of the employment effects of active labour market programmes in Poland

We estimate the employment effects of training, intervention works (subsidised employment), and public works programmes in Poland. The analysis is based on retrospective monthly calendar information on the labour force state and active labour market programme (ALMP) participation between January 1992 and August 1996. The data are obtained from the Polish Labour Force Survey of August 1996 and its Supplement on Labour Market Policies. Because there is no general agreement on the appropriate evaluation methodology when working with non-experimental data, we use two widely applied approaches to identify causal effects. First, non-parametric estimates of the programme effects are obtained on the basis of matched samples. Second, we use traditional econometric modelling in the form of duration models with unobserved individual heterogeneity. We find that training improves the employment opportunities of both men and women, whereas intervention and public works do not: intervention works prolong unemployment for both genders as do public works for men. The number of observations on women in public works is too small to make a statistically safe statement. In general, all ALMP effects are larger in absolute size for men than for women. --evaluation,microeconometrics,active labour market policy,Poland