Temperature gradient driven lasing and stimulated cooling

A laser can be understood as thermodynamic engine converting heat to a coherent single mode field close to Carnot efficiency. From this perspective spectral shaping of the excitation light generates a higher effective temperature on the pump than on the gain transition. Here, using a toy model of a quantum well structure with two suitably designed tunnel-coupled wells kept at different temperature, we study a laser operated on an actual spatial temperature gradient between pump and gain region. We predict gain and narrow band laser emission for a sufficient temperature gradient and resonator quality. Lasing appears concurrent with amplified heat flow and points to a new form of stimulated solid state cooling. Such a mechanism could raise the operating temperature limit of quantum cascade lasers by substituting phonon emission driven injection, which generates intrinsic heat, by an extended model with phonon absorption steps

Coulomb driven energy boost of heavy ions for laser plasma acceleration

An unprecedented increase of kinetic energy of laser accelerated heavy ions is demonstrated. Ultra thin gold foils have been irradiated by an ultra short laser pulse at an intensity of $6\times 10^{19}$ W/cm$^{2}$. Highly charged gold ions with kinetic energies up to $> 200$ MeV and a bandwidth limited energy distribution have been reached by using $1.3$ Joule laser energy on target. $1$D and $2$D Particle in Cell simulations show how a spatial dependence on the ions ionization leads to an enhancement of the accelerating electrical field. Our theoretical model considers a varying charge density along the target normal and is capable of explaining the energy boost of highly charged ions, leading to a higher efficiency in laser acceleration of heavy ions

Demonstration of a hybrid collisional soft-x-ray laser

Includes bibliographical references (pages 033803-4-033803-5).We report on a demonstration of x-ray-ultraviolet amplification following collisional excitation in a discharge-created plasma waveguide irradiated by a picosecond optical laser pulse. A capillary discharge was used to generate a sulfur plasma column with a large concentration of Ne-like ions and a radially concave electron density profile. The intense short laser pulse rapidly heated the electrons, producing amplification in the 3p 1S0-3s 1P1 transition of Ne-like S at 60.8 nm. The integrated gain-length product obtained exciting a 3-cm-long capillary with a 0.46-J short laser pulse is 6.8. The beam divergence was observed to decrease as a function of plasma column length, reaching 2.5 mrad for 30-mm-long capillaries. This hybrid laser pumping scheme could lead to a new generation of efficient tabletop soft-x-ray lasers

Fast capillary discharge plasma as a preformed medium for longitudinally pumped collisional x-ray lasers

Includes bibliographical references (pages 219-220).Simulations of plasma dynamics in a fast capillary discharge are presented. The temporal dependence of the plasma column's resistance validates the one-dimensional model that was used in the numerical simulations. Numerical analysis of the laser absorption determines the pump parameter range for efficient excitation of longitudinally pumped transient collisional x-ray lasers

Acquisition of pneumococci specific effector and regulatory Cd4+ T cells localising within human upper respiratory-tract mucosal lymphoid tissue

The upper respiratory tract mucosa is the location for commensal Streptococcus (S.) pneumoniae colonization and therefore represents a major site of contact between host and bacteria. The CD4(+) T cell response to pneumococcus is increasingly recognised as an important mediator of immunity that protects against invasive disease, with data suggesting a critical role for Th17 cells in mucosal clearance. By assessing CD4 T cell proliferative responses we demonstrate age-related sequestration of Th1 and Th17 CD4(+) T cells reactive to pneumococcal protein antigens within mucosal lymphoid tissue. CD25(hi) T cell depletion and utilisation of pneumococcal specific MHCII tetramers revealed the presence of antigen specific Tregs that utilised CTLA-4 and PDL-1 surface molecules to suppress these responses. The balance between mucosal effector and regulatory CD4(+) T cell immunity is likely to be critical to pneumococcal commensalism and the prevention of unwanted pathology associated with carriage. However, if dysregulated, such responses may render the host more susceptible to invasive pneumococcal infection and adversely affect the successful implementation of both polysaccharide-conjugate and novel protein-based pneumococcal vaccines

How Much Can We Trust Maternal Ratings of Early Child Development in Disadvantaged Samples?

An increasing number of panel studies use short screening questionnaires to assess infant development. Although some research examines the validity of screening questionnaires for middleclass families, knowledge about their accuracy in disadvantaged households is scarce. This paper validates a short screening questionnaire included in the German Socio-Economic Panel (SOEP) with the Bayley Scales for Infant Development (BSID) as an external criterion with a disadvantaged population. The results reveal significant correlations between the screening questionnaire ratings and the BSID scores for disadvantaged mothers. However, the concordance of maternal ratings and test results decreased in mothers with multiple risk burdens

Effects of Early Childhood Intervention on Fertility and Maternal Employment: Evidence from a Randomized Controlled Trial

This paper presents the results of a randomized study of a home visiting program implemented in Germany for low-income, first-time mothers. A major goal of the program is to improve the participants' economic self-sufficiency and family planning. I use administrative data from the German social security system and detailed telephone surveys to examine the effects of the intervention on maternal employment, welfare benefits, and household composition. The study reveals that the intervention unintentionally decreased maternal employment and increased subsequent births. These results contradict those of previous studies from the United States, where home visiting programs successfully increased employment and decreased fertility. Analyzing the reason for the different results, suggests that the program interacts with low employment incentives and generous welfare state arrangements for disadvantaged mothers with young children in Germany

Protective Role of Programmed Death 1 Ligand 1 (PD-L1)in Nonobese Diabetic Mice : The Paradox in Transgenic Models

OBJECTIVE—Coinhibitory signals mediated via programmed death 1 (PD-1) receptor play a critical role in downregulating immune responses and in maintaining peripheral tolerance. Programmed death 1 ligand 1 (PD-L1), the interacting ligand for PD-1, widely expressed in many cell types, acts as a tissue-specific negative regulator of pathogenic T-cell responses. We investigated the protective potential of PD-L1 on autoimmune diabetes by transgenically overexpressing PD-L1 in pancreatic β-cells in nonobese diabetic (NOD) mice