49,345 research outputs found
Ultrastructural alteration of mouse lung by prolonged exposure to mixtures of helium and oxygen
Observed changes consist mainly of blebbing of capillary endothelium and alveolar epithelium, which is quite possibly indicative of cellular edema; also, there can be observed highly-convoluted basement membrane, alveolar debris, and increased numbers of platelets
Design and simulation of InGaAs/AlAsSb quantum-cascade lasers for short wavelength emission
The design and simulation of an In-0.53Ga-0.47As/Al-0.56As-0.44Sb quantum-cascade laser emitting in the near infrared is presented. Designed using a self-consistent rate equation solver coupled with an energy balance rate equation, the proposed laser has a calculated population inversion of ~20% at 77 K and sufficient gain to achieve room-temperature laser emission at λ ~2.8 µm. Threshold currents in the range 4–8 kA/cm2 are estimated as the temperature increases from 77 K to 300 K. The output characteristics of the proposed laser are compared to an existing λ ~3.1 µm In-0.53Ga-0.47As/Al-0.56As-0.44Sb quantum-cascade structure presented in the literature
Thermal storage experience at the MSSTF and plans for the future
The background of thermal storage development at the Midtemperature Solar Systems Test Facility is reviewed. The problems which were encountered are discussed and a course of action for resolving the problems is outlined. Scaling effects of going from laboratory models to full-size applications were determined and applied to thermal storage needs in near-term solar projects
The development of a power spectral density processor for C and L band airborne radar scatterometer sensor systems
A real-time signal processor was developed for the NASA/JSC L-and C-band airborne radar scatterometer sensor systems. The purpose of the effort was to reduce ground data processing costs. Conversion of two quadrature channels of data (like and cross polarized) was made to obtain Power Spectral Density (PSD) values. A chirp-z transform (CZT) approach was used to filter the Doppler return signal and improved high frequency and angular resolution was realized. The processors have been tested with record signals and excellent results were obtained. CZT filtering can be readily applied to scatterometers operating at other wavelengths by altering the sample frequency. The design of the hardware and software and the results of the performance tests are described in detail
Clawback Provisions in Real Estate Investment Trusts
Using a sample of 195 unique real estate investment trusts (REITs), we examine factors related to the adoption of clawback provisions within managerial compensation contracts. In general, we find strong and consistent empirical evidence that clawback provision are directly related to firm size, complexity, leverage, growth options, monitoring incentives, and CEO performance incentives. We also find that clawbacks are associated with enhanced market and accounting performance, with stronger performance relations observed for adoption decisions tied directly to regulatory mandates. In sum, we conclude compensation clawback provisions represent a value-relevant, strategic governance mechanism for REITs
Fabrication and characterization of smart fabric using energy storage fibres
Fibre supercapacitors were designed and manufactured using a dip-coating method. Their electrochemical properties were characterized using a VersaSTAT 3 workstation. Chinese ink with a fine dispersion of carbon and binder was coated as the electrode material. The specific capacitance per unit length of a copper fibre supercapacitor with the length of 41 cm reached 34.5 mF/cm. When this fibre supercapacitor was bent on rods with a diameter of 10.5 cm, the specific capacitance per length was 93% of the original value (without bending). It showed that these fibre supercapacitors have good flexibility and energy storage capacity. Furthermore, the fibre supercapacitor in the fabric showed the same capacitance before and after weaving.The European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement no. [281063]
A new quantum fluid at high magnetic fields in the marginal charge-density-wave system -(BEDT-TTF)Hg(SCN) (where ~K and Rb)
Single crystals of the organic charge-transfer salts
-(BEDT-TTF)Hg(SCN) have been studied using Hall-potential
measurements (K) and magnetization experiments ( = K, Rb). The data show
that two types of screening currents occur within the high-field,
low-temperature CDW phases of these salts in response to time-dependent
magnetic fields. The first, which gives rise to the induced Hall potential, is
a free current (), present at the surface of the sample.
The time constant for the decay of these currents is much longer than that
expected from the sample resistivity. The second component of the current
appears to be magnetic (), in that it is a microscopic,
quasi-orbital effect; it is evenly distributed within the bulk of the sample
upon saturation. To explain these data, we propose a simple model invoking a
new type of quantum fluid comprising a CDW coexisting with a two-dimensional
Fermi-surface pocket which describes the two types of current. The model and
data are able to account for the body of previous experimental data which had
generated apparently contradictory interpretations in terms of the quantum Hall
effect or superconductivity.Comment: 13 pages, 11 figure
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An Investigation into the Effect of the Shell on SALM Processed Parts
Shell Assisted Layer Manufacturing (SALM) is a novel process for rapid prototyping/
tooling/ manufacture (RP/RT/RM) which is presently undergoing feasibility studies. SALM is
based on layered manufacturing technology (LMT). Initially it develops the shell (boundaries)
of a selected layer using a technique similar to fused deposition modelling (FDM). The
developed shell is filled with a UV curable resin and is exposed to UV radiation for curing.
This procedure is repeated until the complete part is built. This paper compares and contrasts
properties of parts made using two options available with the SALM technique: building the
part using a soluble shell (FDM support structure material, finally dissolved to recover the
part); or using a polymer material such as ABS that is bonded with the resin whilst making
the part.Mechanical Engineerin
Spatial Relationship between Solar Flares and Coronal Mass Ejections
We report on the spatial relationship between solar flares and coronal mass
ejections (CMEs) observed during 1996-2005 inclusive. We identified 496
flare-CME pairs considering limb flares (distance from central meridian > 45
deg) with soft X-ray flare size > C3 level. The CMEs were detected by the Large
Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric
Observatory (SOHO). We investigated the flare positions with respect to the CME
span for the events with X-class, M-class, and C-class flares separately. It is
found that the most frequent flare site is at the center of the CME span for
all the three classes, but that frequency is different for the different
classes. Many X-class flares often lie at the center of the associated CME,
while C-class flares widely spread to the outside of the CME span. The former
is different from previous studies, which concluded that no preferred flare
site exists. We compared our result with the previous studies and conclude that
the long-term LASCO observation enabled us to obtain the detailed spatial
relation between flares and CMEs. Our finding calls for a closer flare-CME
relationship and supports eruption models typified by the CSHKP magnetic
reconnection model.Comment: 7 pages; 4 figures; Accepted by the Astrophysical Journa
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