Design Of Prototype Prosthesis For A Canine With A Right Front Limb Deformity As An Alternate Approach To Stabilize Gait And Withstand Gait Forces

Congenital and developmental limb deformities in canines are rare and can occur as a genetic disorder or be caused by extrinsic factors. Without surgery to correct the deformity, conservative management can be implemented to manage exercise and restrict high-intensity activity of the canine. However, any alteration to the normal gait and locomotive biomechanics of a canine can have significant long-term effects on the musculoskeletal health and quality of life of the canine. To improve quality of life and provide an alternative and more cost-effective approach to surgery, a custom prosthetic was designed and developed for a canine born with a congenital right forelimb deformity. Since canine prosthetics that are currently on the market are limited and expensive, the goal of this thesis was to create a durable and inexpensive prosthetic to stabilize the gait of a canine. A 1-year-old German Shepherd was the single subject of this research project. The major results indicated that the custom-designed, 3D printed prosthetic parts, which included the foot and the body of the prosthetic, were strong enough to withstand the high-impact forces and stresses experienced during the gait of a canine. The results also indicated that the prosthetic was comfortable and did not cause any pain or discomfort to the canine, as well as the prosthetic leg and foot being the correct length to stabilize the gait of the canine and redistribute the body weight of the tripod canine to that of a tetrapod canine. This study also developed and outlined a feasible fabrication process that could be repeated and used to produce other custom prosthetics for canines with rare congenital or development limb deformities as an alternative to surgery. In a future study, fatigue testing, tensile testing, and impact testing should be performed to determine the failure points. Fatigue testing is a critical factor in determining failure of a part

Measuring antibiotic availability and use in 20 low- and middle-income countries

Objective To assess antibiotic availability and use in health facilities in low- and middle-income countries, using the service provision assessment and service availability and readiness assessment surveys. Methods We obtained data on antibiotic availability at 13 561 health facilities in 13 service provision assessment and 8 service availability and readiness assessment surveys. In 10 service provision assessment surveys, child consultations with health-care providers were observed, giving data on antibiotic use in 22 699 children. Antibiotics were classified as access, watch or reserve, according to the World Health Organization’s AWaRe categories. The percentage of health-care facilities across countries with specific antibiotics available and the proportion of children receiving antibiotics for key clinical syndromes were estimated. Findings The surveys assessed the availability of 27 antibiotics (19 access, 7 watch, 1 unclassified). Co-trimoxazole and metronidazole were most widely available, being in stock at 89.5% (interquartile range, IQR: 11.6%) and 87.1% (IQR: 15.9%) of health facilities, respectively. In contrast, 17 other access and watch antibiotics were stocked, by fewer than a median of 50% of facilities. Of the 22 699 children observed, 60.1% (13 638) were prescribed antibiotics (mostly co-trimoxazole or amoxicillin). Children with respiratory conditions were most often prescribed antibiotics (76.1%; 8972/11 796) followed by undifferentiated fever (50.1%; 760/1518), diarrhoea (45.7%; 1293/2832) and malaria (30.3%; 352/1160). Conclusion Routine health facility surveys provided a valuable data source on the availability and use of antibiotics in low- and middle-income countries. Many access antibiotics were unavailable in a majority of most health-care facilities

Dissipative Taylor-Couette flows under the influence of helical magnetic fields

The linear stability of MHD Taylor-Couette flows in axially unbounded cylinders is considered, for magnetic Prandtl number unity. Magnetic fields varying from purely axial to purely azimuthal are imposed, with a general helical field parameterized by \beta=B_\phi/B_z. We map out the transition from the standard MRI for \beta=0 to the nonaxisymmetric Azimuthal MagnetoRotational Instability (AMRI) for \beta\to \infty. For finite \beta, positive and negative wave numbers m, corresponding to right and left spirals, are no longer identical. The transition from \beta=0 to \beta\to\infty includes all the possible forms of MRI with axisymmetric and nonaxisymmetric modes. For the nonaxisymmetric modes, the most unstable mode spirals in the opposite direction to the background field. The standard (\beta=0) MRI is axisymmetric for weak fields (including the instability with the lowest Reynolds number) but is nonaxisymmetric for stronger fields. If the azimuthal field is due in part to an axial current flowing through the fluid itself (and not just along the central axis), then it is also unstable to the nonaxisymmetric Tayler instability, which is most effective without rotation. For large \beta this instability has wavenumber m=1, whereas for \beta\simeq 1 m=2 is most unstable. The most unstable mode spirals in the same direction as the background field.Comment: 9 pages, 11 figure

Global axisymmetric Magnetorotational Instability with density gradients

We examine global incompressible axisymmetric perturbations of a differentially rotating MHD plasma with radial density gradients. It is shown that the standard magnetorotational instability, (MRI) criterion drawn from the local dispersion relation is often misleading. If the equilibrium magnetic field is either purely axial or purely toroidal, the problem reduces to finding the global radial eigenvalues of an effective potential. The standard Keplerian profile including the origin is mathematically ill-posed, and thus any solution will depend strongly on the inner boundary. We find a class of unstable modes localized by the form of the rotation and density profiles, with reduced dependence on boundary conditions.Comment: 22 pages, 5 figure

Helicity and alpha-effect by current-driven instabilities of helical magnetic fields

Helical magnetic background fields with adjustable pitch angle are imposed on a conducting fluid in a differentially rotating cylindrical container. The small-scale kinetic and current helicities are calculated for various field geometries, and shown to have the opposite sign as the helicity of the large-scale field. These helicities and also the corresponding $\alpha$-effect scale with the current helicity of the background field. The $\alpha$-tensor is highly anisotropic as the components $\alpha_{\phi\phi}$ and $\alpha_{zz}$ have opposite signs. The amplitudes of the azimuthal $\alpha$-effect computed with the cylindrical 3D MHD code are so small that the operation of an $\alpha\Omega$ dynamo on the basis of the current-driven, kink-type instabilities of toroidal fields is highly questionable. In any case the low value of the $\alpha$-effect would lead to very long growth times of a dynamo in the radiation zone of the Sun and early-type stars of the order of mega-years.Comment: 6 pages, 7 figures, submitted to MNRA

Relativistic stars with purely toroidal magnetic fields

We investigate the effects of the purely toroidal magnetic field on the equilibrium structures of the relativistic stars. The master equations for obtaining equilibrium solutions of relativistic rotating stars containing purely toroidal magnetic fields are derived for the first time. To solve these master equations numerically, we extend the Cook-Shapiro-Teukolsky scheme for calculating relativistic rotating stars containing no magnetic field to incorporate the effects of the purely toroidal magnetic fields. By using the numerical scheme, we then calculate a large number of the equilibrium configurations for a particular distribution of the magnetic field in order to explore the equilibrium properties. We also construct the equilibrium sequences of the constant baryon mass and/or the constant magnetic flux, which model the evolution of an isolated neutron star as it loses angular momentum via the gravitational waves. Important properties of the equilibrium configurations of the magnetized stars obtained in this study are summarized as follows ; (1) For the non-rotating stars, the matter distribution of the stars is prolately distorted due to the toroidal magnetic fields. (2) For the rapidly rotating stars, the shape of the stellar surface becomes oblate because of the centrifugal force. But, the matter distribution deep inside the star is sufficiently prolate for the mean matter distribution of the star to be prolate. (3) The stronger toroidal magnetic fields lead to the mass-shedding of the stars at the lower angular velocity. (4) For some equilibrium sequences of the constant baryon mass and magnetic flux, the stars can spin up as they lose angular momentum.Comment: 13 figures, 7 tables, submitted to PR

The Origin of Solar Activity in the Tachocline

Solar active regions, produced by the emergence of tubes of strong magnetic field in the photosphere, are restricted to within 35 degrees of the solar equator. The nature of the dynamo processes that create and renew these fields, and are therefore responsible for solar magnetic phenomena, are not well understood. We analyze the magneto-rotational stability of the solar tachocline for general field geometry. This thin region of strong radial and latitudinal differential rotation, between the radiative and convective zones, is unstable at latitudes above 37 degrees, yet is stable closer to the equator. We propose that small-scale magneto-rotational turbulence prevents coherent magnetic dynamo action in the tachocline except in the vicinity of the equator, thus explaining the latitudinal restriction of active regions. Tying the magnetic dynamo to the tachocline elucidates the physical conditions and processes relevant to solar magnetism.Comment: 10 pages, 1 figure, accepted for publication in ApJ

Investigation of the field-induced ferromagnetic phase transition in spin polarized neutron matter: a lowest order constrained variational approach

In this paper, the lowest order constrained variational (LOCV) method has been used to investigate the magnetic properties of spin polarized neutron matter in the presence of strong magnetic field at zero temperature employing $AV_{18}$ potential. Our results indicate that a ferromagnetic phase transition is induced by a strong magnetic field with strength greater than $10^{18}\ G$, leading to a partial spin polarization of the neutron matter. It is also shown that the equation of state of neutron matter in the presence of magnetic field is stiffer than the case in absence of magnetic field.Comment: 23 pages, 9 figures Phys. Rev. C (2011) in pres