135,812 research outputs found
Small V/STOL aircraft analysis, volume 1
A study has been made of the economic viability of advanced V/STOL aircraft concepts in performing general aviation missions. A survey of general aviation aircraft users, operators, and manufacturers indicated that personnel transport missions formulated around business executive needs, commuter air service, and offshore oil supply are the leading potential areas of application using VTOL aircraft. Advanced VTOL concepts potentially available in the late 1970 time period were evaluated as alternatives to privately owned contemporary aircraft and commercial airline service in satisfying these personnel transport needs. Economic analysis incorporating the traveler's value of time as the principle figure of merit were used to identify the relative merits of alternative VTOL air transportation concepts
Exposure of a tendon extracellular matrix to synovial fluid triggers endogenous and engrafted cell death: A mechanism for failed healing of intrathecal tendon injuries
Aim: The purpose of this study was to investigate the effect of normal synovial fluid (SF) on exposed endogenous tendon-derived cells (TDC) and engrafted mesenchymal stem cells (MSCs) within the tendon extracellular matrix.
Methods: Explants from equine superficial digital flexor (extra-synovial) and deep digital flexor tendons (DDFT) from the compressed, intra-synovial and the tensile, extra-synovial regions were cultured in allogeneic or autologous SF-media. Human hamstring explants were cultured in allogeneic SF. Explant viability was assessed by staining. Proliferation of equine monolayer MSCs and TDCs in SF-media and co-culture with DDFT explants was determined by alamarblue®. Non-viable Native Tendon matrices (NNTs) were re-populated with MSCs or TDCs and cultured in SF-media. Immunohistochemical staining of tendon sections for the apoptotic proteins caspase-3, -8 and -9 was performed.
Results: Contact with autologous or allogeneic SF resulted in rapid death of resident tenocytes in equine and human tendon. SF did not affect the viability of equine epitenon cells, or of MSCs and TDCs in monolayer or indirect explant co-culture. MSCs and TDCs, engrafted into NNTs, died when cultured in SF. Caspase-3, -8 and -9 expression was greatest in SDFT explants exposed to allogeneic SF.
Conclusions: The efficacy of cells administered intra-synovially for tendon lesion repair is likely to be limited, since once incorporated into the matrix, cells become vulnerable to the adverse effects of SF. These observations could account for the poor success rate of intra-synovial tendon healing following damage to the epitenon and contact with SF, common with most soft tissue intra-synovial pathologies
Regenerative medicine in equine orthopaedics: what and when?
The development of regenerative medicine has opened up many new therapeutic avenues in veterinary medicine. The focus of regenerative medicine in the horse lies primarily in the musculoskeletal system, where the consequences of injury make tendons, ligaments and joints particularly desirable targets for such interventions. This article focuses on what has been learned from the use of regenerative medicine in naturally-occurring tendon, ligament and joint disease in the horse
Failure properties of loaded fiber bundles having a lower cutoff in fiber threshold distribution
Presence of lower cutoff in fiber threshold distribution may affect the
failure properties of a bundle of fibers subjected to external load. We
investigate this possibility both in a equal load sharing (ELS) fiber bundle
model and in local load sharing (LLS) one. We show analytically that in ELS
model, the critical strength gets modified due to the presence of lower cutoff
and it becomes bounded by an upper limit. Although the dynamic exponents for
the susceptibility and relaxation time remain unchanged, the avalanche size
distribution shows a permanent deviation from the mean-fiels power law. In the
LLS model, we analytically estimate the upper limit of the lower cutoff above
which the bundle fails at one instant. Also the system size variation of
bundle's strength and the avalanche statistics show strong dependence on the
lower cutoff level.Comment: 7 pages and 7 figure
Long season wheat
Agronomy of long season wheats, 87AL9, 87AL10, 87ES3, 87ES4, 87JE2, 87JE3, 87MT8, 87MT9 and 87NA9. Septoria control in long season wheat, 87E4 and 87MT10. Nitrogen response by long season wheat, 87ES5 and 87JE4. Phenology of long season wheats, 87E5 and 87MT11
Rate constants and Arrhenius parameters for the reactions of OH radicals and Cl atoms with CF3CH2OCHF2, CF3CHClOCHF2 and CF3CH2OCClF2, using the discharge-flow/resonance fluorescence method
Rate constants have been determined for the reactions of OH radicals and Cl atoms with the three partially halogenated methyl-ethyl ethers, CFCHOCHF, CFCHClOCHF and CFCHOCClF, using discharge-flow techniques to generate the OH radicals and the Cl atoms and resonance fluorescence to observe changes in their relative concentrations in the presence of added ether. For each combination of radical and ether, experiments were carried out at three temperatures between 292 and 410 K, yielding the following Arrhenius expressions for the rate constants within this range of temperature:
OH + CFCHOCHF: = (2.00.8) 10 exp( – 2110 150 K / T) cm molecule s
OH + CFCHClOCHF: = (4.5 1.3) 10 exp( – 940 100 K / T) cm molecule s
OH + CFCHOCClF: = (1.6 0.6) 10 exp( – 1100 125 K / T) cm molecule s
Cl + CFCHOCHF: = (6.1 1.4) 10 exp( – 1830 90 K / T) cm molecule s
Cl + CFCHClOCHF: = (7.8 2.6) 10 exp( – 2980 130 K / T) cm molecule s
Cl + CFCHOCClF: = (2.2 0.2) 10 exp( – 2700 40 K / T) cm molecule s
The results are compared with those obtained previously for the same and related reactions of OH radicals and Cl atoms, and the atmospheric implications of the results are considered briefly
Altruistic Contents of Quantum Prisoner's Dilemma
We examine the classical contents of quantum games. It is shown that a
quantum strategy can be interpreted as a classical strategies with effective
density-dependent game matrices composed of transposed matrix elements. In
particular, successful quantum strategies in dilemma games are interpreted in
terms of a symmetrized game matrix that corresponds to an altruistic game plan.Comment: Revised according to publisher's request: 4 pgs, 2 fgs, ReVTeX4. For
more info, go to http://www.mech.kochi-tech.ac.jp/cheon
Integer quantum Hall effect on a six valley hydrogen-passivated silicon (111) surface
We report magneto-transport studies of a two-dimensional electron system
formed in an inversion layer at the interface between a hydrogen-passivated
Si(111) surface and vacuum. Measurements in the integer quantum Hall regime
demonstrate the expected sixfold valley degeneracy for these surfaces is
broken, resulting in an unequal occupation of the six valleys and anisotropy in
the resistance. We hypothesize the misorientation of Si surface breaks the
valley states into three unequally spaced pairs, but the observation of odd
filling factors, is difficult to reconcile with non-interacting electron
theory.Comment: 4 pages, 4 figures, to appear in Physical Review Letter
- …