Texture development and transformation strain of a cold-rolled Ti50-Ni45-Cu5 alloy

Shape memory alloys (SMAs) are finding increased use as functional materials in the aerospace, energy and medical industries 1 J. van Humbeeck, Shape Memory Materials and Phenomena—Fundamental Aspects and Applications, p. 3771, vol. 246, MRS, Pittsburgh, PA (1992).(1), (2) and (3). Shape memory behaviour is based on the recovery of large amounts of induced strain upon heating and/or unloading. This transformation strain is a result of the reversible growth of certain favoured martensite variants during martensite transformation and/or stressing [4] and [5]. For single crystal SMAs, the favoured variants are those which result in the maximum transformation strain for a specific orientation. This has been well established for several common single crystal SMAs such as TiNi, CuZnAl and CuAlNi [4] and [6].\ud \ud For polycrystalline SMAs, it is not clear which variants are favoured. Anisotropic behaviour in SMAs has been interpreted based on the anisotropy data of single crystal materials using the concept of the selection of favoured martensite variants. This has met with only limited success in work on NiTi alloys due to the lack of information about which variants are formed [7] and [8]. An investigation of the anisotropic behaviour of textured SMAs was thus conducted in order to determine which martensite variants develop during thermal cycling of a commercial TiNiCu SMA. The relationship between the observed variant development, changes in texture and anisotropic shape memory behaviour are discussed in light of models using the concept of favoured martensite variants

Extrapancreatic insulin effect of glibenclamide

In eight patients with uncomplicated non insulin dependent diabetes mellitus, serum insulin levels, serum C-peptide levels and blood glucose levels were measured before and after oral administration of glibenclamide 0.1 mg/kg body weight and a test meal, or after a test meal alone. The rise in serum insulin levels persisted longer after glibenclamide. The initial rise in serum insulin was of the same magnitude in both situations, as was the rise in serum C-peptide levels during the entire 5 h study. It is concluded that glibenclamide is able to maintain a more protonged increase in serum insulin levels by inhibiting the degradation of insulin in the vascular endothelial cells of the liver. The inhibition contributes to the blood glucose lowering effect of glibenclamide

The Effect of the Outer Lindblad Resonance of the Galactic Bar on the Local Stellar Velocity Distribution

Hydro-dynamical modeling of the inner Galaxy suggest that the radius of the outer Lindblad resonance (OLR) of the Galactic bar lies in the vicinity of the Sun. How does this resonance affect the distribution function in the outer parts of a barred disk, and can we identify any effect of the resonance in the velocity distribution f(v) actually observed in the solar neighborhood? To answer these questions, detailed simulations of f(v) in the outer parts of an exponential stellar disks with nearly flat rotation curves and a rotating central bar have been performed. For a model resembling the old stellar disk, the OLR causes a distinct feature in f(v) over a significant fraction of the outer disk. For positions <2kpc outside the OLR radius and at bar angles of \~10-70 degrees, f(v) inhibits a bi-modality between the low-velocity stars moving like the local standard of rest (LSR) and a secondary mode of stars predominantly moving outward and rotating more slowly than the LSR. Such a bi-modality is indeed present in f(v) inferred from the Hipparcos data for late-type stars in the solar neighborhood. If one interpretes this observed bi-modality as induced by the OLR -- and there are hardly any viable alternatives -- then one is forced to deduce that the OLR radius is slightly smaller than Ro. Moreover, by a quantitative comparison of the observed with the simulated distributions one finds that the pattern speed of the bar is 1.85+/-0.15 times the local circular frequency, where the error is dominated by the uncertainty in bar angle and local circular speed. Also other, less prominent but still significant, features in the observed f(v) resemble properties of the simulated velocity distributions, in particular a ripple caused by orbits trapped in the outer 1:1 resonance.Comment: 14 pages, 10 figures (Fig.2 in full resolution available upon request), accepted for publication in A

The properties of the Galactic bar implied by gas kinematics in the inner Milky Way

Longitude-velocity (l-V) diagrams of H I and CO gas in the inner Milky Way have long been known to be inconsistent with circular motion in an axisymmetric potential. Several lines of evidence suggest that the Galaxy is barred, and gas flow in a barred potential could be consistent with the observed ``forbidden'' velocities and other features in the data. We compare the H I observations to l-V diagrams synthesized from 2-D fluid dynamical simulations of gas flows in a family of barred potentials. The gas flow pattern is very sensitive to the parameters of the assumed potential, which allows us to discriminate among models. We present a model that reproduces the outer contour of the H I l-V diagram reasonably well; this model has a strong bar with a semimajor axis of 3.6 kpc, an axis ratio of approximately 3:1, an inner Lindblad resonance (ILR), and a pattern speed of 42 km/s/kpc, and matches the data best when viewed from 34\deg to the bar major axis. The behavior of the models, combined with the constraint that the shocks in the Milky Way bar should resemble those in external barred galaxies, leads us to conclude that wide ranges of parameter space are incompatible with the observations. In particular we suggest that the bar must be fairly strong, must have an ILR, and cannot be too end-on, with the bar major axis at 35\deg +/- 5\deg to the line of sight. The H I data exhibit larger forbidden velocities over a wider longitude range than are seen in molecular gas; this important difference is the reason our favored model differs so significantly from other recently proposed models.Comment: 23 pages, 14 figures, 1 table, uses emulateapj and psfig, 640 kb. Submitted to Ap

SPH Simulations of Galactic Gaseous Disk with Bar: Distribution and Kinematic Structure of Molecular Clouds toward the Galactic Center

We have performed Smoothed Particle Hydrodynamic (SPH) simulations to study the response of molecular clouds in the Galactic disk to a rotating bar and their subsequent evolution in the Galactic Center (GC) region. The Galactic potential in our models is contributed by three axisymmetric components (massive halo, exponential disk, compact bulge) and a non-axisymmetric bar. These components are assumed to be invariant in time in the frame corotating with the bar. Some noticeable features such as an elliptical outer ring, spiral arms, a gas-depletion region, and a central concentration have been developed due to the influence of the bar. The rotating bar induces non-circular motions of the SPH particles, but hydrodynamic collisions tend to suppress the random components of the velocity. The velocity field of the SPH particles is consistent with the kinematics of molecular clouds observed in HCN (1-0) transition; these clouds are thought to be very dense clouds. However, the l-v diagram of the clouds traced by CO is quite different from that of our SPH simulation, being more similar to that obtained from simulations using collisionless particles. The $l-v$ diagram of a mixture of collisional and collisionless particles gives better reproduction of the kinematic structures of the GC clouds observed in the CO line. The fact that the kinematics of HCN clouds can be reproduced by the SPH particles suggests that the dense clouds in the GC are formed via cloud collisions induced by rotating bar.Comment: 31 pages, 10 pigures, accepted for publication in Ap

Functional outcome of patients with spinal cord injury: rehabilitation outcome study

Objective: To increase our knowledge of neurological recovery and functional outcome of patients with spinal cord injuries in order to make more successful rehabilitation programmes based on realistic goals.Design: Descriptive analysis of data gathered in an information system.Setting: Rehabilitation centre in The Netherlands with special department for patients with spinal cord injuries.Subjects: Fifty-five patients with traumatic spinal cord lesions admitted to the rehabilitation centre from 1988 to 1994. Main outcome measures: The functional improvement was presented in terms of progress in independence in nine daily activity skills. Independence was rated on a four-point scale.Results: From admission to discharge, lesions in 100% of patients with tetraplegia and 96% of patients with paraplegia remained complete. Significant progress in independence was made in self-care, ambulation and bladder and bowel care. Differences were found in the extent of functional improvement between subgroups of patients with different levels and extent of lesion. Contrary to expectations based on theoretical models, patients with complete paraplegia did not achieve maximal independence in self-care. Independent walking was only attained by patients with incomplete lesions. Regarding outcome of bladder and bowel care, poor results were found, especially the independence in defaecation and toilet transfers.Conclusions: The results of this study provided more insight into the functional outcome of a group of patients with traumatic spinal cord injury. More research is needed to evaluate the rehabilitation programmes for these patients

Vocational perspectives after spinal cord injury

Objective: To give insight into the vocational situation several years after a traumatic spinal cord injury (SCI) and describe the personal experiences and unmet needs; to give an overview of health and functional status per type of SCI and their relationship with employment status. Design: Descriptive analysis of data from a questionnaire. Setting: Dutch rehabilitation centre with special department for patients with spinal cord injuries. Subjects: Fifty-seven patients with a traumatic SCI, aged 18-60 years, admitted to the rehabilitation centre from 1990 to 1998. Main measures: Questionnaire with items related to vocational outcome, job experiences, health and functional status. Results: Of 49 patients who were working at the moment of SCI 60% currently had a paid job. Vocational outcome was related to a higher educational level. A significant relation between the SCI-specific health and functional status and employment was not found. The respondents who changed to a new employer needed more time to resume work, but seemed more satisfied with the job and lost fewer working hours than those who resumed work with the same employer. In spite of reasonable to good satisfaction with the current work situation, several negative experiences and unmet needs were reported. Conclusions: Despite a high participation in paid work following SCI, the effort of the disabled worker to have and keep a job should not be underestimated