Fermi-Edge Superfluorescence from a Quantum-Degenerate Electron-Hole Gas

We report on the observation of spontaneous bursts of coherent radiation from a quantum-degenerate gas of nonequilibrium electron-hole pairs in semiconductor quantum wells. Unlike typical spontaneous emission from semiconductors, which occurs at the band edge, the observed emission occurs at the quasi-Fermi edge of the carrier distribution. As the carriers are consumed by recombination, the quasi-Fermi energy goes down toward the band edge, and we observe a continuously red-shifting streak. We interpret this emission as cooperative spontaneous recombination of electron-hole pairs, or superfluorescence, which is enhanced by Coulomb interactions near the Fermi edge. This novel many-body enhancement allows the magnitude of the spontaneously developed macroscopic polarization to exceed the maximum value for ordinary superfluorescence, making electron-hole superfluorescence even more "super" than atomic superfluorescence.Comment: 10 pages, 5 figure

The effect of montelukast on exhaled nitric oxide of alveolar and bronchial origin in inhaled corticosteroid-treated asthma

SummaryBackgroundInhaled corticosteroid therapy suppresses nitric oxide levels (NO) of airway origin but not necessarily NO of alveolar or small airway origin. Systemic therapy with an oral anti-leukotriene agent may suppress NO production in distal airways and alveoli not reached by inhaled therapy.MethodsAdult patients with mild asthma were treated for 3 weeks with inhaled fluticasone 250μg twice daily then with inhaled fluticasone plus oral montelukast 10mg daily for 3 additional weeks. We monitored exhaled NO (eNO), spirometry, lung volumes, and asthma symptoms scores at baseline and at the end of each treatment period. In a subset of patients, we continued with montelukast monotherapy and repeated these measurements.ResultsIn the 18 patients studied, pulmonary function parameters and asthma symptom scores were not altered significantly from baseline by any therapy. The total eNO at baseline was 55±35.3ppb, dropping to 28.1±15.3ppb (p=0.005) after 3 weeks of fluticasone and to 23.5±14ppb (p=0.001 vs. baseline) after the addition of montelukast. The trend towards reduced total eNO with the combination therapy vs. monotherapy was not statistically significant. Alveolar eNO dropped from 4.2±2.4 at baseline to 3.0±1.5 (p=0.1) after fluticasone and then to 2.2±0.9 (p=0.08 vs. baseline) after fluticasone plus montelukast, increasing then to 3.8±1.8 after montelukast alone (p=0.6 vs. baseline).ConclusionsLeukotriene receptor antagonists administered systemically might decrease small airway/alveolar sites of inflammation when combined to inhaled corticosteroid therapy

Utilisation of second-trimester spontaneous and induced abortion services in public hospitals in Mexico, 2007–2015

Describe las tendencias temporales y geográficas en la utilización de servicios de aborto en el segundo trimestre dentro de las instalaciones en todo México. Utiliza datos del 2007-2015 del Sistema Automatizado de alta hospitalaria de México (SAEH) para identificar eventos abortivos en el segundo trimestre (ICD O02-O08) en hospitales públicos en los 32 estados de México. Describe la utilización, calcula las tasas utilizando datos de población y utilizamos la regresión logística para identificar los factores a nivel estatal y de la mujer (marginación a nivel municipal, ley de aborto a nivel estatal) asociados con la utilización de los servicios del segundo trimestre versus los del primer trimestre. Identifica 145 956 abortos en el segundo trimestre, o el 13.4% del total de hospitalizaciones documentadas por aborto entre 2007 y 2015. La tasa de utilización anual del aborto en el segundo trimestre se mantuvo constante, entre 0.5 y 0.6 por 1000 mujeres de 15 a 44 años. Las mujeres que viven en municipios altamente marginados tenían 1.43 probabilidades más altas de utilizar servicios de aborto en su segundo trimestre que en el primer trimestre, en comparación con las mujeres en municipios con baja marginación (IC del 95%: 1.18 a 1.73). Vivir en un estado con una excepción de salud o anomalía fetal a las restricciones de aborto no se asoció con una mayor utilización de los servicios de aborto en el segundo trimestre. Los resultados sugieren que existe la necesidad de todos los tipos de servicios de aborto en el segundo trimestre en México. Para mejorar los resultados de salud para las mujeres mexicanas, especialmente las más vulnerables, se debe garantizar el acceso a servicios de aborto seguro en el segundo trimestre mediante la implementación de las excepciones legales actuales y una atención renovada a la capacitación de los proveedores de atención médica

Astrobiology Survey of a Lava Cave at Lava Beds National Monument by a Rover Carrying a Remote Sensing Instrument Payload

We report here on a survey of a lava tube cave by a rover that is instrumented for astrobiology missions. The NASA Ames testbed rover, CaveR, was deployed in Valentine Cave in Lava Beds National Monument (N. CA, USA) during August of 2018. The rover carried an instrument package consisting of Near Infrared and Visible Spectrometer System (NIRVSS) a point spectrometer operating in 1590-3400 nm range, sensitive to H2O and -OH bearing minerals, pyroxenes, and carbonates (Roush, et al 2018); the bore sighted Drill Operations Camera (DOC), a monochrome imager illuminated by LEDs at 410, 540, 640, 740, 905 and 940 nm; a Realsense depth sensor system for 3D model generation; and a high resolution DSLR stereo camera. The payload was mounted on a tiltable instrument platform attached to the left side of the rover. The rover was driven manually in the cave by field operators, following instructions from a remote science operations team, and simulating a mission concept with science-guided autonomy. A simulated mission took place for 3 days with a team of 3 scientists selecting targets and interpreting data from the payload. To begin the mission, the rover drove along one wall of the cave imaging continuously with the Realsense in 20 m cave segments, three total. At the start of each day, the images from a 20m segment and a panorama stitched from them were provided to the science team to examine. The science team used these data to prioritize specific points along the cave wall for the collection of NIRVSS, DOC, and DSLR data. The objective of the data collection was to identify and study putative biological and mineralogical features in the cave. The data were delivered in xGDS, a customized mapping, planning, and data base management software developed at NASA Ames (Lee, et al 2013). Once the targets for further observations were selected, a plan for collecting the observations (positions in the cave and pointing for each requested observation) was constructed using xGDS and delivered to a rover team to execute the science data collection plan. Acquired data were delivered back to the science team for analysis. Preliminary results from the experiment illustrate the utility of the system (rover plus payload) to study the cave geology and mineralogy and its potential for identifying biomineral features

Renormalized Energies of Superfluorescent Bursts from an Electron-Hole Magneto-plasma with High Gain in InGaAs Quantum Wells

We study light emission properties of a population-inverted 2D electron-hole plasma in a quantizing magnetic field. We observe a series of superfluorescent bursts, discrete both in time and energy, corresponding to the cooperative recombination of electron-hole pairs from different Landau levels. The emission energies are strongly renormalized due to many-body interactions among the photogenerated carriers, exhibiting red-shifts as large as 20 meV at 15 T. However, the magnetic field dependence of the lowest Landau level emission line remains excitonic at all magnetic fields. Interestingly, our time-resolved measurements show that this lowest-energy burst occurs only after all upper states become empty, suggesting that this excitonic stability is related to the `hidden symmetry' of 2D magneto-excitons expected in the magnetic quantum limit.Comment: 5 pages, 4 figure

Regulation of mammary gland branching morphogenesis by the extracellular matrix and its remodeling enzymes.

A considerable body of research indicates that mammary gland branching morphogenesis is dependent, in part, on the extracellular matrix (ECM), ECM-receptors, such as integrins and other ECM receptors, and ECM-degrading enzymes, including matrix metalloproteinases (MMPs) and their inhibitors, tissue inhibitors of metalloproteinases (TIMPs). There is some evidence that these ECM cues affect one or more of the following processes: cell survival, polarity, proliferation, differentiation, adhesion, and migration. Both three-dimensional culture models and genetic manipulations of the mouse mammary gland have been used to study the signaling pathways that affect these processes. However, the precise mechanisms of ECM-directed mammary morphogenesis are not well understood. Mammary morphogenesis involves epithelial 'invasion' of adipose tissue, a process akin to invasion by breast cancer cells, although the former is a highly regulated developmental process. How these morphogenic pathways are integrated in the normal gland and how they become dysregulated and subverted in the progression of breast cancer also remain largely unanswered questions

Martian atmosphere as observed by VIRTIS‐M on Rosetta spacecraft

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95134/1/jgre2651.pd