Interpretation of anomalous temperature dependence of anti-Stokes photoluminescence at GaInP2/GaAs interface

The anomalous temperature dependence of anti-Stokes photoluminescence (ASPL) at the GaInP2/GaAs interface was studied. A localized state luminescence model was employed to interpret the temperature-dependence of the peak position of the ASPL. The results show that the localization of the up-converted carriers plays an important role in radiative recombination producing the ASPL. The studies also show that the microscopic mechanism of thermal quenching of ASPL at GaInP2/GaAs interface is unmasked.published_or_final_versio

Aligning Manifolds of Double Pendulum Dynamics Under the Influence of Noise

This study presents the results of a series of simulation experiments that evaluate and compare four different manifold alignment methods under the influence of noise. The data was created by simulating the dynamics of two slightly different double pendulums in three-dimensional space. The method of semi-supervised feature-level manifold alignment using global distance resulted in the most convincing visualisations. However, the semi-supervised feature-level local alignment methods resulted in smaller alignment errors. These local alignment methods were also more robust to noise and faster than the other methods.Comment: The final version will appear in ICONIP 2018. A DOI identifier to the final version will be added to the preprint, as soon as it is availabl

Management of Extracranial Carotid Artery Aneurysms:17 Years» Experience

AbstractObjectives:a retrospective review of seventeen-year (1980–1996) experience of the management of extracranial carotid artery aneurysms.Patients and methods:sixty-six aneurysms of extracranial carotid artery were seen in 63 patients. The diagnosis was confirmed by angiography in 51 patients and duplex ultrasonography in twelve. Twenty-eight (42%) patients had an atherosclerotic aneurysm, twenty-two (33%) had false aneurysms secondary to trauma, nine were congenital and seven were mycotic. All underwent aneurysm resection with saphenous-vein-graft interposition as the most common means of reconstruction.Results:one death occurred due to septicaemia in a diabetic patient with a mycotic aneurysm, giving an operative mortality of 1.5%. One patient had an immediate hemiparesis after carotid artery ligation, and three had a hemiparesis within 48 hours of operation (6.1%). After a change in technique to avoid a residual carotid stump, no further neurological problems were encountered in the following 28 patients.Conclusion:extracranial carotid aneurysms may be successfully managed with resection and reconstruction with autogenous saphenous vein. End-to-side anastomosis avoids a blind-ending stump which may be the source of emboli

Low-Lying Dirac Eigenmodes, Topological Charge Fluctuations and the Instanton Liquid Model

The local structure of low-lying eigenmodes of the overlap Dirac operator is studied. It is found that these modes cannot be described as linear combinations of 't Hooft "would-be" zeromodes associated with instanton excitations that underly the Instanton Liquid Model. This implies that the instanton liquid scenario for spontaneous chiral symmetry breaking in QCD is not accurate. More generally, our data suggests that the vacuum fluctuations of topological charge are not effectively dominated by localized lumps of unit charge with which the topological "would-be" zeromodes could be associated.Comment: Presented by I. Horvath at the NATO Advanced Research Workshop "Confinement, Topology, and other Non-Perturbative Aspects of QCD", January 21-27, 2002, Stara Lesna, Slovakia. 12 pages, 6 figures, uses crckapb.st

Temperature-dependent photoluminescence of GaInP/AlGaInP multiple quantum well laser structure grown by metalorganic chemical vapor deposition with tertiarybutylarsine and tertiarybutylphosphine

A GaInP/AlGaInP multiple quantum well laser structure was grown by low-pressure metalorganic chemical vapor deposition with tertiarybutylarsine and tertiarybutylphosphine. Laser diodes fabricated from this structure lased at room temperature. Photoluminescence ~PL! measurements were performed from 10 to 230 K. The PL energy increased with temperature from 10 to 70 K and decreased above 70 K. The former was attributed to thermal activation of trapped carriers due to localization in the quantum wells, while the latter was attributed to temperature-induced band-gap shrinkage. The PL intensity as a function of temperature was fitted by employing two nonradiative recombination mechanisms with good agreement, resulting in two activation energies that correspond to losses of photogenerated carriers to nonradiative centers. © 2003 American Institute of Physics.published_or_final_versio

Observational evidence of a change in radiative forcing due to the indirect aerosol effect

Anthropogenic aerosols enhance cloud reflectivity by increasing the number concentration of cloud droplets, leading to a cooling effect on climate known as the indirect aerosol effect. Observational support for this effect is based mainly on evidence that aerosol number concentrations are connected with droplet concentrations, but it has been difficult to determine the impact of these indirect effects on radiative forcing(1-3). Here we provide observational evidence for a substantial alteration of radiative fluxes due to the indirect aerosol effect. We examine the effect of aerosols on cloud optical properties using measurements of aerosol and cloud properties at two North American sites that span polluted and clean conditions-a continental site in Oklahoma with high aerosol concentrations, and an Arctic site in Alaska with low aerosol concentrations. We determine the cloud optical depth required to fit the observed shortwave downward surface radiation. We then use a cloud parcel model to simulate the cloud optical depth from observed aerosol properties due to the indirect aerosol effect. From the good agreement between the simulated indirect aerosol effect and observed surface radiation, we conclude that the indirect aerosol effect has a significant influence on radiative fluxes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62920/1/nature02234.pd

First Steps towards Underdominant Genetic Transformation of Insect Populations

The idea of introducing genetic modifications into wild populations of insects to stop them from spreading diseases is more than 40 years old. Synthetic disease refractory genes have been successfully generated for mosquito vectors of dengue fever and human malaria. Equally important is the development of population transformation systems to drive and maintain disease refractory genes at high frequency in populations. We demonstrate an underdominant population transformation system in Drosophila melanogaster that has the property of being both spatially self-limiting and reversible to the original genetic state. Both population transformation and its reversal can be largely achieved within as few as 5 generations. The described genetic construct {Ud} is composed of two genes; (1) a UAS-RpL14.dsRNA targeting RNAi to a haploinsufficient gene RpL14 and (2) an RNAi insensitive RpL14 rescue. In this proof-of-principle system the UAS-RpL14.dsRNA knock-down gene is placed under the control of an Actin5c-GAL4 driver located on a different chromosome to the {Ud} insert. This configuration would not be effective in wild populations without incorporating the Actin5c-GAL4 driver as part of the {Ud} construct (or replacing the UAS promoter with an appropriate direct promoter). It is however anticipated that the approach that underlies this underdominant system could potentially be applied to a number of species. Figure

A rapid, efficient, and facile solution for dental hypersensitivity: The tannin–iron complex

Dental hypersensitivity due to exposure of dentinal tubules under the enamel layer to saliva is a very popular and highly elusive technology priority in dentistry. Blocking water flow within exposed dentinal tubules is a key principle for curing dental hypersensitivity. Some salts used in "at home" solutions remineralize the tubules inside by concentrating saliva ingredients. An "in-office" option of applying dense resin sealants on the tubule entrance has only localized effects on well-defined sore spots. We report a self-assembled film that was formed by facile, rapid (4 min), and efficient (approximately 0.5 g/L concentration) dip-coating of teeth in an aqueous solution containing a tannic acid-iron(III) complex. It quickly and effectively occluded the dentinal tubules of human teeth. It withstood intense tooth brushing and induced hydroxyapatite remineralisation within the dentinal tubules. This strategy holds great promise for future applications as an effective and user-friendly desensitizer for managing dental hypersensitivity.111310Ysciescopu

Effect of strengthened standards on Chinese ironmaking and steelmaking emissions

China has produced roughly half of the world’s steel in recent years, but the country’s iron and steel industry is a major source of air pollutants, especially particulate matter, SO2 and NOx emissions. To reduce such emissions, China imposed new emission standards in 2015 and promoted ultralow emission standards in 2019. Here we use measurements from China’s continuous emissions monitoring systems (covering 69–91% of national iron and steel production) to develop hourly, facility-level emissions estimates for China’s iron and steel industry. In turn, we use this data to evaluate the emission reductions related to China’s increasingly stringent policies. We find steady declines in emission concentrations at iron- and steelmaking plants since the 2015 standards were implemented. From 2014 to 2018, particulate matter and SO2 emissions fell by 47% and 42%, respectively, and NOx increased by 3%, even as the production increased by 14%. Moreover, we estimate that if all facilities achieve the ultralow emission standards, particulate matter, SO2 and NOx emissions will drop by a further 50%, 37% and 58%, respectively. Our results thus reveal the substantial benefits of the Chinese government’s interventions to curb emissions from iron and steel production and emphasize the promise of ongoing ultralow emission renovations