Laser-electron beam interaction applied to optical amplifiers and oscillators

Momentum modulation of a relativistic electron beam by a Nd:YAG laser is demonstrated. The electrons, at 100 MeV energy, interact with the laser light in helium gas at standard temperature and pressure. At an angle of 6.55 mrad between the two wavevectors, corresponding to the Cerenkov angle, a given electron remains in a field of constant phase as it passes through the light beam. The experimental arrangement is illustrated showing the trajectories of the electron and light. The particle momentum is measured by a mass spectrometer, and the angle between the wavevectors is controlled by a rotatable mirror. Experimental results indicate that momentum modulation of an electron beam may be used for amplification. A possible configuration for an optical klystron is illustrated

Driving light pulses with light in two-level media

A two-level medium, described by the Maxwell-Bloch (MB) system, is engraved by establishing a standing cavity wave with a linearly polarized electromagnetic field that drives the medium on both ends. A light pulse, polarized along the other direction, then scatters the medium and couples to the cavity standing wave by means of the population inversion density variations. We demonstrate that control of the applied amplitudes of the grating field allows to stop the light pulse and to make it move backward (eventually to drive it freely). A simplified limit model of the MB system with variable boundary driving is obtained as a discrete nonlinear Schroedinger equation with tunable external potential. It reproduces qualitatively the dynamics of the driven light pulse

Improving Public Policy for Children: A Vote for Each Child

Changes in social policy in the United States (US) over the past four decades have provided health insurance for 100 percent of persons over age 65 and decreased poverty for this group while the number of children in poverty has risen and ten million are uninsured. This increasing intergenerational inequity reflects political decisions where children lack a voice. The purposes of this paper are to: 1) summarize, from the fields of ethics, government, law, social welfare and public health, current thinking about enfranchisement of children; 2) review the evolution of voting and representation in the US and identify misperceptions about barriers to equitable representation of children; 3) discuss the legal basis for children being regarded as adults and adult proxy decision making for children; and 4) suggest strategies to stimulate an equitable system of child representation by altering our current system of voting

Non-linear emission spectra of quantum dots strongly coupled to photonic mode

A theory of optical emission of quantum dot arrays in quantum microcavities is developed. The regime of the strong coupling between the quantum dots and photonic mode of the cavity is considered. The quantum dots are modeled as two-level systems. In the low pumping (linear) regime the emission spectra are mainly determined by the superradiant mode where the effective dipoles of the dots oscillate in phase. In the non-linear regime the superradiant mode is destroyed and the emission spectra are sensitive to the parity of quantum dot number. Further increase of the pumping results in the line width narrowing being an evidence of the lasing regime.Comment: 11 pages, 6 figure

Non Linear Compton Scattering of Strong Laser Radiation on Channeled Particles in a Crystal

A version for intense $\gamma$-ray radiation based on the multiphoton scattering of strong laser radiation on relativistic particle beam channeled in a crystal is proposed. The scheme is considered when the incident laser beam and charged paricles beam are counter-propagating and the laser radiation is resonant to the energy levels of transversal motion of channeled particles.Comment: 5 pages, Revte

Initial Metabolic Profiles Are Associated with 7-Day Survival among Infants Born at 22-25 Weeks of Gestation.

OBJECTIVE:To evaluate the association between early metabolic profiles combined with infant characteristics and survival past 7 days of age in infants born at 22-25 weeks of gestation. STUDY DESIGN:This nested case-control consisted of 465 singleton live births in California from 2005 to 2011 at 22-25 weeks of gestation. All infants had newborn metabolic screening data available. Data included linked birth certificate and mother and infant hospital discharge records. Mortality was derived from linked death certificates and death discharge information. Each death within 7 days was matched to 4 surviving controls by gestational age and birth weight z score category, leaving 93 cases and 372 controls. The association between explanatory variables and 7-day survival was modeled via stepwise logistic regression. Infant characteristics, 42 metabolites, and 12 metabolite ratios were considered for model inclusion. Model performance was assessed via area under the curve. RESULTS:The final model included 1 characteristic and 11 metabolites. The model demonstrated a strong association between metabolic patterns and infant survival (area under the curve [AUC] 0.885, 95% CI 0.851-0.920). Furthermore, a model with just the selected metabolites performed better (AUC 0.879, 95% CI 0.841-0.916) than a model with multiple clinical characteristics (AUC 0.685, 95% CI 0.627-0.742). CONCLUSIONS:Use of metabolomics significantly strengthens the association with 7-day survival in infants born extremely premature. Physicians may be able to use metabolic profiles at birth to refine mortality risks and inform postnatal counseling for infants born at <26 weeks of gestation

Miscellaneous Problems

Contains reports on two research projects

Eine bessere Politik für Kinder: jedem Kind eine Stimme

Veränderungen in der Sozialpolitik der Vereinigten Staaten im Laufe der letzten vier Jahrzehnte haben 100 Prozent der Menschen über 65 mit einer Gesundheitsversicherung versehen und die Armut dieser Gruppe reduziert, während die Zahl der Kinder in Armut gestiegen ist und zehn Millionen unversichert sind. Diese zunehmende intergenerationelle Ungerechtigkeit spiegelt politische Entscheidungen wider, in denen Kindern eine Stimme fehlt. Die Ziele des vorliegenden Artikels sind 1) eine Zusammenfassung gegenwärtiger Ansichten zum Stimmrecht für Kinder aus den Bereichen Ethik, Regierungslehre, Recht, Sozial- und Gesundheitswesen; 2) eine Überprüfung der Entwicklung von Abstimmung und Repräsentation in den USA und eine Identifikation der Fehleinschätzungen, die eine gleichberechtigte Repräsentation von Kindern behindern; 3)eine Diskussion der Rechtsgrundlage, die Kinder als Erwachsene begreift und elterliches Entscheiden in Vertretung für Kinder gestattet; sowie 4) Vorschläge von Strategien, um ein gleichberechtigtes Repräsentationssystem für Kinder durch Änderung unseres gegenwärtiges Wahlsystems anzuregen

Improving Public Policy for Children: A Vote for Each Child

Changes in social policy in the United States (US) over the past four decades have provided health insurance for 100 percent of persons over age 65 and decreased poverty for this group while the number of children in poverty has risen and ten million are uninsured. is increasing intergenerational inequity reflects political decisions where children lack a voice. The purposes of this paper are to: 1) summarize, from the fields of ethics, government, law, social welfare and public health, current thinking about enfranchisement of children; 2) review the evolution of voting and representation in the US and identify misperceptions about barriers to equitable representation of children; 3) discuss the legal basis for children being regarded as adults and adult proxy decision making for children; and 4) suggest strategies to stimulate an equitable system of child representation by altering our current system of voting