1,117 research outputs found
Reoperation rates following intramedullary nailing versus external fixation of Gustilo Type 3A open tibia shaft fractures
Background: Open tibia fractures are among the most difficult to manage due to the lack of soft tissue coverage and poor blood supply. This is especially true in developing settings primarily due to a lack of resources. Both locked Intramedullary Nailing (IM) and External Fixation (EF) are two possible modalities for surgical treatment of open tibia fractures. However, it is unknown at this time which one is most suitable in low resource regions especially with regards to the risk of serious complications requiring reoperation. This study was conducted to identify which method is safest and minimizes this risk in patients with open tibia fractures.Methodology: A prospective cohort study of Gustilo 3A open tibia shaft factures treated either by intramedullary nailing or external fixation was conducted from March 2013 to February 2014 at Muhimbili Orthopaedic Institute (Dar es Salaam, Tanzania). Follow-up was conducted at 2, 6 10, 14, and 18 weeks postoperatively. The primary outcome assessed was all-cause reoperation.Results: Fifty patients were enrolled and completed follow-up at all-time points; twenty-six were treated with IM nail and twenty-four were treated by EF. There were 9 (37.5%) EF patients who required reoperation compared to 1(3.8%) IM nail patient (p=0.004). Reasons for reoperation among EF patients were infection (2 patients), malalignment (3 patients), and delayed union (4 patients). The one IM nail patient presented with signs of infection and wound dehiscence at 14 weeks postoperatively. No patients presented with hardware failure or malrotation.Conclusion: Treatment of Gustilo Type 3A open tibia shaft fractures with interlocking intramedullary nailing results in lower reoperation rate in the early stages of treatment compared to uniplanar external fixation.Keywords: Orthopaedic surgery, Tanzania, Intramedullary nail, External fixation, Open tibia fractur
Inhibitory effect of rhubarb on intestinal α-glucosidase activity in type 1 diabetic rats
Purpose: To investigate the inhibitory effect of rhubarb on α-glucosidase activity in the small intestine of rats with type 1 diabetes.Methods: Type 1 diabetic rat model was established by intraperitoneally injecting 30 male SD rats with 1 % streptozocin (STZ). Rats with fasting blood glucose > 11 mmol/L (24) were used for the study. The rats were randomly divided into three equal groups including control, acarbose and rhubarb groups. Arcabose® (20 mg/kg /day) and rhubarb (100 mg/kg /day) were given by intra-gastric route via insertion of the cannula through the esophagus. Daily fasting blood glucose and daily postprandial glucose levels were assayed for all groups. On day 6, postprandial blood glucose, blood levels of C-peptide and insulin, and intestinal α-glucosidase were also determined.Results: There were no significant differences in levels of C-peptide, insulin and fasting blood glucose between control, Acarbose® and rhubarb groups (p > 0.05). However, α-glucosidase activity at 0, 30, 60 and 120 min in the rhubarb group was 1759.2, 1812.8, 1379.8 and 772.1 U, respectively,) while in the Acarbose® group it was 178.6, 1260.1, 1126.5, 599.2 U, respectively. α-Glucosidase activity in both groups initially showed an increase (p < 0.05), followed by a decline from 60 to 120 min (p ˂ 0.05). After 120 min, α-glucosidase activity in each of the two groups was significantly decreased compared with untreated control (1200 U) (p ˂ 0.05).Conclusion: The inhibitory effect of rhubarb on intestinal α-glucosidase activity of Type 1 diabetic rats is comparable to that of Arcabose®.This suggests that this plant may have clinically potent anti-diabetic properties.Keywords: Type 1 diabetes, α-Glucosidase activity, Acarbose®, Rhubarb, Postprandial glucose leve
Spin filtering and magnetoresistance in ballistic tunnel junctions
We theoretically investigate magnetoresistance (MR) effects in connection
with spin filtering in quantum-coherent transport through tunnel junctions
based on non-magnetic/semimagnetic heterostructures. We find that spin
filtering in conjunction with the suppression/enhancement of the spin-dependent
Fermi seas in semimagnetic contacts gives rise to (i) spin-split kinks in the
MR of single barriers and (ii) a robust beating pattern in the MR of double
barriers with a semimagnetic well. We believe these are unique signatures for
quantum filtering.Comment: Added references + corrected typo
Landau and dynamical instabilities of Bose-Einstein condensates with superfluid flow in a Kronig-Penney potential
We study the elementary excitations of Bose-Einstein condensates in a
one-dimensional periodic potential and discuss the stability of superfluid flow
based on the Kronig-Penney model. We analytically solve the Bogoliubov
equations and calculate the excitation spectrum. The Landau and dynamical
instabilities occur in the first condensate band when the superfluid velocity
exceeds certain critical values, which agrees with the result of condensates in
a sinusoidal potential. It is found that the onset of the Landau instability
coincides with the point where the perfect transmission of low-energy
excitations is forbidden, while the dynamical instability occurs when the
effective mass is negative. It is well known that the condensate band has a
peculiar structure called swallowtail when the periodic potential is shallow
compared to the mean field energy. We find that the upper side of the
swallowtail is dynamically unstable although the excitations have the linear
dispersion reflecting the positive effective mass.Comment: 6 pages, 2 figures, Proceedings of the International Symposium on
Quantum Fluids and Solids (QFS2006
Spin oscillations in transient diffusion of a spin pulse in n-type semiconductor quantum wells
By studying the time and spatial evolution of a pulse of the spin
polarization in -type semiconductor quantum wells, we highlight the
importance of the off-diagonal spin coherence in spin diffusion and transport.
Spin oscillations and spin polarization reverse along the the direction of spin
diffusion in the absence of the applied magnetic field are predicted from our
investigation.Comment: 5 pages, 4 figures, accepted for publication in PR
Modelling of Optical Detection of Spin-Polarized Carrier Injection into Light-Emitting Devices
We investigate the emission of multimodal polarized light from Light Emitting
Devices due to spin-aligned carriers injection. The results are derived through
operator Langevin equations, which include thermal and carrier-injection
fluctuations, as well as non-radiative recombination and electronic g-factor
temperature dependence. We study the dynamics of the optoelectronic processes
and show how the temperature-dependent g-factor and magnetic field affect the
polarization degree of the emitted light. In addition, at high temperatures,
thermal fluctuation reduces the efficiency of the optoelectronic detection
method for measuring spin-polarization degree of carrier injection into
non-magnetic semicondutors.Comment: 15 pages, 7 figures, replaced by revised version. To appear in Phys.
Rev.
Magnetism in systems with various dimensionality: A comparison between Fe and Co
A systematic ab initio study is performed for the spin and orbital moments
and for the validity of the sum rules for x-ray magnetic circular dichroism for
Fe systems with various dimensionality (bulk, Pt-supported monolayers and
monatomic wires, free-standing monolayers and monatomic wires). Qualitatively,
the results are similar to those for the respective Co systems, with the main
difference that for the monatomic Fe wires the term in the spin sum rule
is much larger than for the Co wires. The spin and orbital moments induced in
the Pt substrate are also discussed.Comment: 4 page
Effects of pressurization and surface tension on drawing Ge-Sb-Se chalcogenide glass suspended-core fiber
Drawing chalcogenide glass microstructured optical fibers efficiently requires a good understanding of the different drawing conditions beforehand, due to the high cost of the chalcogenide glass materials. A simulation based on Stokes’ model that includes pressurization and glass surface tension is validated with respect to drawing a Ge28Sb12Se60 chalcogenide glass single hole capillary, as well as microstructured optical fiber with three holes, with different pressurizations. Suspended-core Ge28Sb12Se60 fibers with bridges just hundreds of nanometer wide are drawn using parameters predicted by the simulations. These fibers should be suitable for applications such as generating mid-infrared (MIR) supercontinuum based on chalcogenide glasses.Wu Shengling, Simon Fleming, Boris T. Kuhlmey, Heike Ebendorff-Heidepriem and Alessio Stefan
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