Management and radiographic outcomes of femoral head fractures.

BackgroundFemoral head fractures are uncommon injuries. Small series constitute the majority of the available literature. Surgical approach and fracture management is variable. The purpose of this study was to evaluate the incidence, method of treatment, and outcomes of consecutive femoral head fractures at a regional academic Level I trauma center.Materials and methodsA retrospective review of a prospective database was performed over a 13-year period. All AO/OTA 31C femoral head fractures were identified. A surgical approach and fixation method was recorded. Clinical and radiographic evaluation was performed for patients with 6 months or greater follow-up. Radiographs were evaluated for fixation failure, heterotopic ossification (HO), avascular necrosis (AVN) and post-traumatic arthritis.ResultsWe identified 164 fractures in 163 patients; 147 fractures were available for review. Treatment was operative reduction and internal fixation (ORIF) in 78 (53.1%), fragment excision in 37 (25.1%) and non-operative in 28 (19%). An anterior approach and mini-fragment screws were used in the majority of patients treated with fixation. Sixty-nine fractures had follow-up greater than 6 months. Sixty-two fractures (89.9%) proceeded to uneventful union. All Pipkin III fractures failed operative fixation. Six patients developed AVN, seven patients had a known conversion to hip arthroplasty; HO developed in 28 (40.6%) patients and rarely required excision.ConclusionsFractures of the femoral head are rare. An anterior approach can be used for fragment excision or fixation using mini-fragment screws. Pipkin III fractures represent catastrophic injuries. Non-bridging, asymptomatic HO is common. AVN and posttraumatic degenerative disease of the hip occur but are uncommon.Level of evidenceIV-prognostic

Research program on fractured petroleum reservoirs. Final report, January 1, 1996--December 31, 1996

Multiphase flow in fractured porous media is a complex problem. While the study of single phase flow in a fractured or a layered medium can be pursued by some kind of averaging process, there is no meaning to averaging two-phase flow when capillarity is an active force. For a two-layer system comprised of high and low permeable layers, the performance of gas-oil gravity can be less efficient than the homogeneous low permeable medium. On the other hand, heterogeneity may enhance water imbibition due to capillarity. Due to the above and various other complexities, current tools for predicting the performance of fractured hydrocarbon reservoirs are not reliable. Based on the research work carried out at the Reservoir Engineering Research Institute, and some other Institutions, a good deal of progress has been made in recent years. But still we are a long way from good predictive reservoir models. In this final report, we summarize some of our achievements in the understanding of multiphase flow in fractured media. Since some of the features of two-phase flow in fractured and layered many are similar due to the capillary forces, the work includes progress in both types of media. There are some basic issues of flow in both fractured and unfractured media that are currently unresolved. These issues include: (1) new phase formation such as the formation of liquid phase in gas condensate reservoirs, and gas phase formation in solution gas drive process and (2) composition variation due to thermal convection and diffusion processes. In the following, a brief summary of our findings in the last three years during the course of the project is presented

A Comparative Study of the Immscible Density Currents Using the SPH And VOF-LES Methods

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Subthreshold and near-threshold kaon and antikaon production in proton-nucleus reactions

The differential production cross sections of K^+ and K^- mesons have been measured at the ITEP proton synchrotron in p+Be, p+Cu collisions under lab angle of 10.5^0, respectively, at 1.7 and 2.25, 2.4 GeV beam energies. A detailed comparison of these data with the results of calculations within an appropriate folding model for incoherent primary proton-nucleon, secondary pion-nucleon kaon and antikaon production processes and processes associated with the creation of antikaons via the decay of intermediate phi mesons is given. We show that the strangeness exchange process YN->NNK^- gives a small contribution to the antikaon yield in the kinematics of the performed experiment. We argue that in the case when antikaon production processes are dominated by the channels with KK^- in the final state, the cross sections of the corresponding reactions are weakly influenced by the in-medium kaon and antikaon mean fields.Comment: 24 pages. accepted for publication at J.Phys.

Ge/SiGe parabolic quantum wells

Quantum wells with parabolic confining potentials allow the realization of semiconductor heterostructures mimicking the physical properties of a quantum harmonic oscillator. Here we report the attempt of attaining such parabolic quantum wells (PQWs) within the Ge/SiGe material platform. Multiple PQWs featuring different widths and composition have been epitaxially grown and characterized by means of high-resolution x-ray diffraction and scanning transmission electron microscopy. The compositional profile is seen to deviate slightly from an ideal parabola, but the quantum confined states are almost equally spaced within the valence and conduction band as indicated by photoreflectance measurements and k . p modelling

Numerical simulation of turbidity current using V2-f turbulence model

The deposition behavior of fine sediment is an important phenomenon, and yet unclear to engineers concerned about reservoir sedimentation. An elliptic relaxation turbulence model ( 2 n - f model) has been used to simulate the motion of turbid density currents laden with fine solid particles. During the last few years, the 2 n - f turbulence model has become increasingly popular due to its ability to account for near-wall damping without use of damping functions. The 2 n - f model has also proved to be superior to other RANS (Reynolds-Averaged Navier-Stokes) methods in many fluid flows where complex flow features are present. This current becomes turbulent at low Reynolds number (order 1000). The k -e model, which was standardized for high Reynolds number and isotropic turbulence flow, cannot simulate the anisotropy and nonhomogenous behavior near the wall. In this study, the turbidity current with a uniform velocity and concentration enters the channel via a sluice gate into a lighter ambient fluid and moves forward down-slope. The model has been validated by available experimental data sets. Moreover, results have been compared with the standard k -e turbulence model. The deposition of particles and the effects of their fall velocity on concentration distribution, Richardson number, and the deposition rate are also investigated. The results show that the coarse particles settle rapidly and make the deposition rate higher

Experimental Investigation of Turbulence Specifications of Turbidity Currents

The present study investigates the turbulence characteristic of turbidity current experimentally. The three-dimensional Acoustic-Doppler Velocimeter (ADV) was used to measure the instantaneous velocity and characteristics of the turbulent flow. The experiments were conducted in a three-dimensional channel for different discharge flows, concentrations, and bed slopes. Results are expressed at various distances from the inlet, for all flow rates, slopes and concentrations as the distribution of turbulence energy, Reynolds stress and the turbulent intensity. It was concluded that the maximum turbulence intensity happens in both the interface and near the wall. Also, it was observed that the turbulence intensity reaches its minimum where maximum velocity occurs

Determination of Settling Tanks Performance Using an Eulerian- Lagrangian Method

Circulation regions always exist in settling tanks. These regions reduce the tank’s performance and decrease its effective volume. The recirculation zones would result in short-circuiting and high flow mixing problems. The inlet position would also affect the size and location of the recirculation region. Using a proper baffle configuration could substantially increase the performance of the settling tanks. A common procedure for the comparison of the performances of different tanks has been using the Flow Through Curves (FTC) method. FTC, however, neglects tendencies for particles sedimentation. In this work, a new method for evaluation of the settling tanks performance is presented. The new method which is referred to as the particle Tracking Method (PTM) is based on an Eulerian-Lagrangian approach. In this paper, by using FTC and PTM the effects of the inlet position and the baffle configuration on the hydraulic performance of the primary settling tanks were studied and results were compared. Then, shortcomings of the FTC approach were stated. The optimal positioning of the baffles was also determined though a series of computer simulations