2,419 research outputs found
Cargo/Logistics Airlift System Study (CLASS), Volume 2
Air containerization is discussed in terms of lower freight rates, size and pallet limitations, refrigeration, backhaul of empties, and ownership. It is concluded that there is a need for an advance air cargo system as indicated by the industry/transportation case studies, and a stimulation of the air cargo would result in freight rate reductions
Cargo/Logistics Airlift System Study (CLASS), Volume 1
Current and advanced air cargo systems are evaluated using industrial and consumer statistics. Market and commodity characteristics that influence the use of the air mode are discussed along with a comparison of air and surface mode on typical routes. Results of on-site surveys of cargo processing facilities at airports are presented, and institutional controls and influences on air cargo operations are considered
Cargo/Logistics Airlift System Study (CLASS), Executive Summary
The current air cargo system is analyzed along with advanced air cargo systems studies. A forecast of advanced air cargo system demand is presented with cost estimates. It is concluded that there is a need for a dedicated advance air cargo system, and with application of advanced technology, reductions of 45% in air freight rates may be achieved
Experimentally Constrained Molecular Relaxation: The case of hydrogenated amorphous silicon
We have extended our experimentally constrained molecular relaxation
technique (P. Biswas {\it et al}, Phys. Rev. B {\bf 71} 54204 (2005)) to
hydrogenated amorphous silicon: a 540-atom model with 7.4 % hydrogen and a
611-atom model with 22 % hydrogen were constructed. Starting from a random
configuration, using physically relevant constraints, {\it ab initio}
interactions and the experimental static structure factor, we construct
realistic models of hydrogenated amorphous silicon. Our models confirm the
presence of a high frequency localized band in the vibrational density of
states due to Si-H vibration that has been observed in a recent vibrational
transient grating measurements on plasma enhanced chemical vapor deposited
films of hydrogenated amorphous silicon.Comment: 13 pages, 4 figure
Thermal Conductivity and Specific Heat Measurements of Candidate Structural Materials for the JWST Optical Bench
The James Webb Space Telescope will include an optical bench known as the integrated science instrument module (ISIM). Candidate structural materials for the ISIM must have low density, high stiffness, high thermal conductivity, and low thermal expansion coefficient at the operating temperature of 30 Kelvin. The specific heat is also important in modeling the on-orbit cooldown. We built two different systems for measuring the thermal conductivity and specific heat of samples between 4 Kelvin and 290 Kelvin. Both experiments were carefully designed to minimize potential errors due to radiative heat transfer. We chose the cooling system and instrumentation to allow long-term unattended operation. Software was developed to automate each experiment. It used an algorithm designed to ensure that each system was in thermal equilibrium before a measurement was taken. We describe the two experiments and present the data
Intermuscular Adipose Tissue Is Muscle Specific and Associated with Poor Functional Performance
Purpose. People with obesity, diabetes, and peripheral neuropathy have high levels of intermuscular adipose tissue (IMAT) volume which has been inversely related to physical function. We determined if IMAT is muscle specific, if calf IMAT is different between a healthy obese group (HO), a group with diabetes mellitus (D), and a group with diabetes mellitus and peripheral neuropathy (DN), and if IMAT volume or the ratio of IMAT/muscle volume is related to physical function in these groups. Methods. 10 healthy obese people, 11 with type 2 diabetes, 24 with diabetes and peripheral neuropathy, had assessments of muscle morphology, physical function and muscle performance. Results. The gastrocnemius muscle had a higher ratio of IMAT/muscle volume than any other muscle or compartment. There were no differences between groups in calf muscle or IMAT volumes. Calf IMAT was inversely related to physical performance on the 6-minute walk test (r = −0.47) and physical performance test (r = −0.36). IMAT/muscle volume was inversely related to physical performance (PPT, r = −0.44; 6 MW r = −0.48; stair power, r = −0.30). Conclusions. IMAT accumulation varies in calf muscles, is highest in the gastrocnemius muscle, and is associated with poor physical performance
C-C bond-forming reactions of ground-state aryl halides under reductive activation
Under basic conditions aryl halides can undergo SRN1 reactions, BHAS reactions and benzyne formations. Appropriate complex substrates afford an opportunity to study inherent selectivities. SRN1 reactions are usually favoured under photoactivated conditions, but this paper reports their success using ground-state and transition metal-free conditions. In benzene, the enolate salt 12, derived by deprotonation of diketopiperazine 11, behaves as an electron donor, and assists the initiation of the reactions, but in DMSO, it is not required. The outcomes are compared and contrasted with a recent photochemical study on similar substrates. A particular difference is the prevalence of hydride shuttle reactions under relatively mild thermal conditions
Cryogenic Thermal Emittance Measurements on Small-Diameter Stainless Steel Tubing
The Mid Infrared Instrument aboard the James Webb Space Telescoep includes a mechanical cryocooler which cools its detectors to their 6 K operating temperature. The refrigerant flows through several meters of approximately 2 mm diameter 304L stainless steel tubing, with some sections gold plated, and some not, which are exposed to their environment. An issue of water freezing onto the tube surfaces is mitigated by a running a warm gas through the lines to sublimate the water. To model the effect of this process on nearby instruments, an accurate measure of the tube emittance is needed. Previously we reported the abosprtance of the gold plated stainless steel tubing as a function of source temperature (i.e. its environment). In this work the thermal emittance of the uncoated tubing is measured as a function of its temperature between 100 and 300 K. This value leads to an accurate prediction of the minimum length of time required to thermally recycle the system. We report the technique and present the results
Optimized Dipole Antennas on Photonic Band gap crystals
Cataloged from PDF version of article.Photonic band gap crystals have been used as a perfectly reflecting substrate for planar dipole antennas in the 12–15 GHz regime. The position, orientation, and driving frequency of the dipole antenna on the photonic band gap crystal surface, have been optimized for antenna performance and directionality. Virtually no radiated power is lost to the photonic crystal resulting in gains and radiation efficiencies larger than antennas on other conventional dielectric substrates.
© 1995 American Institute of Physic
Mutation of the Traj18 gene segment using TALENs to generate Natural Killer T cell deficient mice.
Invariant Natural Killer T (iNKT) cells are a unique subset of T lymphocytes that have been implicated in both promoting and suppressing a multitude of immune responses. In mice, iNKT cells express T cell antigen receptors (TCRs) comprising a unique TCRα rearrangement between the Trav11 and Traj18 gene segments. When paired with certain Trbv TCRβ chains, these TCRs recognize lipid antigens presented by the major histocompatibility complex (MHC) class I-like molecule, CD1d. Until recently, the sole model of iNKT deficiency targeted the Jα18, which is absolutely required to form the TCR with the appropriate antigenic specificity. However, these mice were demonstrated to have a large reduction in TCR repertoire diversity, which could confound results arising from studies using these mice. Here, we have created a new NKT-deficient mouse strain using transcription activator-like effector nuclease (TALEN) technology to only disrupt the expression of Jα18, leaving the remaining Jα repertoire unperturbed. We confirm that these mice lack iNKT cells and do not respond to lipid antigen stimulation while the development of conventional T cells, regulatory T cells, and type Ib NKT cells is normal. This new mouse strain will serve as a new model of iNKT cell deficiency to facilitate our understanding of iNKT biology
- …