Long term storage test of titanium material with liquid fluorine propellant

The compatibility of 6AL-4V Ti with propellant grade GF2 and LF2 at 77 K for up to 3 years was investigated. Titanium double coupons, annealed or heat treated, with 16 or 64 RMS finishes, were immersed in F2 in individual Pyrex capsules and stored under LN2 for 29 and 39 months. Pre and post immersion tests were performed on the propellant and coupons. Chemical analysis of the propellant did not reveal any significant changes due to titanium corrosion. Gravimetric, visual, microscopic, and metallurgical examination with pitting analysis did not reveal gross corrosion of the titanium although pitting appears to be greater after 39 months exposure. The increase in pit size and number raises the possibility of unpredictable crack propagation instability. Fracture toughness tests are necessary to define this possibility

Social Work in Schools in New Zealand: Indigenous Social Work Practice

Social workers have found a new professional presence in New Zealand schools since 2001 following a pilot program in a small cluster of schools in 1999. Schools that are in low socio-economic communities have been selected to engage the services of in-school social workers. These schools have a high proportion of Maori and Pacific Island children and families in a country where Maori make up 15% of the population and Pacific Island families now make up 7% of the population. Maori social service providers are keen to employ Maori social workers so that there is congruence with their clients. These workers must then manage the multiple relationships they encounter in small rural communities in New Zealand. School social work enables helping professionals to work in health and counselling teams with families, contributing to positive Maori development and empowering families

Patient-oriented and performance-based outcomes after knee autologous chondrocyte implantation: a timeline for the first year of recovery

It is well established that autologous chondrocyte implantation (ACI) can require extended recovery postoperatively; however, little information exists to provide clinicians and patients with a timeline for anticipated function during the first year after ACI. Objective: To document the recovery of functional performance of activities of daily living after ACI. Patients: ACI patients (n = 48, 29 male 35.1 ± 8.0 y). Intervention: All patients completed functional tests (weight-bearing squat, walk-across, sit-to-stand, step-up/over, and forward lunge) using the NeuroCom long force plate (Clackamas, OR) and completed patient-reported outcome measures (International Knee Documentation Committee Subjective Knee Evaluation Form, Lysholm, Western Ontario and McMaster Osteoarthritis Index WOMAC, and 36-Item Short-Form Health Survey) preoperatively and 3, 6, and 12 mo postoperatively. Main Outcome Measures: A covariance pattern model was used to compare performance and self-reported outcome across time and provide a timeline for functional recovery after ACI. Results: Participants demonstrated significant improvement in walk-across stride length from baseline (42.0% ± 8.9% height) at 6 (46.8% ± 8.1%) and 12 mo (46.6% ± 7.6%). Weight bearing on the involved limb during squatting at 30°, 60°, and 90° was significantly less at 3 mo than presurgery. Step-up/over time was significantly slower at 3 mo (1.67 ± 0.69 s) than at baseline (1.49 ± 0.33 s), 6 mo (1.51 ± 0.36 s), and 12 mo (1.40 ± 0.26 s). Step-up/over lift-up index was increased from baseline (41.0% ± 11.3% body weight BW) at 3 (45.0% ± 11.7% BW), 6 (47.0% ± 11.3% BW), and 12 mo (47.3% ± 11.6% BW). Forward-lunge time was decreased at 3 mo (1.51 ± 0.44 s) compared with baseline (1.39 ± 0.43 s), 6 mo (1.32 ± 0.05 s), and 12 mo (1.27 ± 0.06). Similarly, forward-lunge impact force was decreased at 3 mo (22.2% ± 1.4% BW) compared with baseline (25.4% ± 1.5% BW). The WOMAC demonstrated significant improvements at 3 mo. All patient-reported outcomes were improved from baseline at 6 and 12 mo postsurgery. Conclusions: Patients' perceptions of improvements may outpace physical changes in function. Decreased function for at least the first 3 mo after ACI should be anticipated, and improvement in performance of tasks requiring weight-bearing knee flexion, such as squatting, going down stairs, or lunging, may not occur for a year or more after surgery

Driven Intrinsic Localized Modes in a Coupled Pendulum Array

Intrinsic localized modes (ILMs), also called discrete breathers, are directly generated via modulational instability in an array of coupled pendulums. These ILMs can be stabilized over a range of driver frequencies and amplitudes. They are characterized by a pi-phase difference between their center and wings. At higher driver frequencies, these ILMs are observed to disintegrate via a pulsating instability, and the mechanism of this breather instability is investigated.Comment: 5 pages, 6 figure

A computational approach to fretting wear prediction at the head-stem taper junction of total hip replacements

Wear is one of the main reasons for failure of modular total hip replacements. Recent evidence suggests that fretting wear occurs at the taper junction which provides fixation between the prosthesis femoral head and stem components. The fine metallic wear debris that is released can lead to adverse soft-tissue reactions which can necessitate a revision surgery. The present study proposes a computational methodology utilising an energy wear law and a 3D finite element model to predict fretting wear at the taper junction. The method is novel in that it simulates the weakening of the initial taper ‘fixation’ (created at impaction of the head onto the stem in surgery) due to the wearing process. The taper fixation is modelled using a contact analysis with overlapped meshes at the taper junction. The reduction in fixation is modelled by progressive removal of the overlap between components based on calculated wear. The fretting wear analysis approach has been shown to model the evolution of wear effectively; however, it has been shown that accurate, quantitative values for wear are critically dependant on mesh refinement, wear scaling factor and fraction, wear coefficient used and knowledge of the device loading history. The method has been implemented with a 3D finite element model of the taper junction of a commercial total hip replacement. This has been used to determine taper wear patterns, wear damage and wear rates which have been shown to be consistant with those found from observation and measurement of retrieved prostheses. The numerical method could be used to consider the effect of design changes and clinical technique on subsequent fretting wear in modular prosthetic devices

Fundamental investigation of losses of skeletal mineral in young adult human males and collaterally in young adult male pigtail monkeys /macacus nemestrima/ through immobilization for varying periods of time, coupled with a study of methods of preven

Skeletal mineral losses in young adult humans and monkeys resulting from immobilizatio

EFFECTS OF RESERVOIR AQUATIC PLANT MANAGEMENT ON RECREATIONAL EXPENDITURES AND REGIONAL ECONOMIC ACTIVITY

Exotic aquatic plant management is a major concern for public reservoir management in many regions of the United States. A study was conducted to measure the effects of alternative aquatic plant management strategies on recreational expenditures and regional economic activity. The study areas was Lake Guntersville, Alabama, and the local economy surrounding the lake. Lake Guntersville is one of the largest reservoirs in the Tennessee Valley Authority system. Results suggested the relatively moderate levels of aquatic plant control are associated with the highest levels of recreation-related economic effects on the economy surrounding Lake Guntersville.Aquatic plants, Input-output analysis, Public reservoir management, Recreational expenditures, Regional economic activity, Resource /Energy Economics and Policy,

Effects of cochlear implantation on binaural hearing in adults with unilateral hearing loss

A FDA clinical trial was carried out to evaluate the potential benefit of cochlear implant (CI) use for adults with unilateral moderate-to-profound sensorineural hearing loss. Subjects were 20 adults with moderate-to-profound unilateral sensorineural hearing loss and normal or near-normal hearing on the other side. A MED-EL standard electrode was implanted in the impaired ear. Outcome measures included: (a) sound localization on the horizontal plane (11 positions, −90° to 90°), (b) word recognition in quiet with the CI alone, and (c) masked sentence recognition with the target at 0° and the masker at −90°, 0°, or 90°. This battery was completed preoperatively and at 1, 3, 6, 9, and 12 months after CI activation. Normative data were also collected for 20 age-matched control subjects with normal or near-normal hearing bilaterally. The CI improved localization accuracy and reduced side bias. Word recognition with the CI alone was similar to performance of traditional CI recipients. The CI improved masked sentence recognition when the masker was presented from the front or from the side of normal or near-normal hearing. The binaural benefits observed with the CI increased between the 1- and 3-month intervals but appeared stable thereafter. In contrast to previous reports on localization and speech perception in patients with unilateral sensorineural hearing loss, CI benefits were consistently observed across individual subjects, and performance was at asymptote by the 3-month test interval. Cochlear implant settings, consistent CI use, and short duration of deafness could play a role in this result

The interaction of phylloxera infection, rootstock, and irrigation on young Concord grapevine growth

Concord roots are moderately resistant to phylloxera, which form nodosities on the fine roots and weaken the root system. Rootstocks and vineyard floor management both have the potential to eliminate or reduce the effect of phylloxera in New York Concord vineyards. Young, container-grown Concord grapevines were used to evaluate the interaction between rootstock (own-rooted, Couderc 3309), irrigation, and phylloxera infection on vine growth. Phylloxera inoculation alone caused a 21 % decrease in vine dry mass and lack of irrigation (mid-day stem water potential: -0.9 to -1.0 M Pa) alone caused a 34 % decrease in vine dry mass. The combination of phylloxera stress and water stress was additive and caused a 54 % decrease in vine dry mass. Because C3309 rootstock is resistant to phylloxera, the grafted vines showed a response to irrigation but not phylloxera inoculation. This container study shows the potential benefits of irrigating own-rooted Concord grapevines or the use of rootstocks without irrigation to withstand phylloxera infection.