Non-invasive quantification of lower limb mechanical alignment in flexion

Objective: Non-invasive navigation techniques have recently been developed to determine mechanical femorotibial alignment (MFTA) in extension. The primary aim of this study was to evaluate the precision and accuracy of an image-free navigation system with new software designed to provide multiple kinematic measurements of the knee. The secondary aim was to test two types of strap material used to attach optical trackers to the lower limb. Methods: Seventy-two registrations were carried out on 6 intact embalmed cadaveric specimens (mean age: 77.8 ± 12 years). A validated fabric strap, bone screws and novel rubber strap were used to secure the passive tracker baseplate for four full experiments with each knee. The MFTA angle was measured under the conditions of no applied stress, valgus stress, and varus stress. These measurements were carried out at full extension and at 30°, 40°, 50° and 60° of flexion. Intraclass correlation coefficients, repeatability coefficients, and limits of agreement (LOA) were used to convey precision and agreement in measuring MFTA with respect to each of the independent variables, i.e., degree of flexion, applied coronal stress, and method of tracker fixation. Based on the current literature, a repeatability coefficient and LOA of ≤3° were deemed acceptable. Results: The mean fixed flexion for the 6 specimens was 12.8° (range: 6–20°). The mean repeatability coefficient measuring MFTA in extension with screws or fabric strapping of the baseplate was ≤2°, compared to 2.3° using rubber strapping. When flexing the knee, MFTA measurements taken using screws or fabric straps remained precise (repeatability coefficient ≤3°) throughout the tested range of flexion (12.8–60°); however, using rubber straps, the repeatability coefficient was >3° beyond 50° flexion. In general, applying a varus/valgus stress while measuring MFTA decreased precision beyond 40° flexion. Using fabric strapping, excellent repeatability (coefficient ≤2°) was observed until 40° flexion; however, beyond 50° flexion, the repeatability coefficient was >3°. As was the case with precision, agreement between the invasive and non-invasive systems was satisfactory in extension and worsened with flexion. Mean limits of agreement between the invasive and non-invasive system using fabric strapping to assess MFTA were 3° (range: 2.3–3.8°) with no stress applied and 3.9° (range: 2.8–5.2°) with varus and valgus stress. Using rubber strapping, the corresponding values were 4.4° (range: 2.8–8.5°) with no stress applied, 5.5° (range: 3.3–9.0°) with varus stress, and 5.6° (range: 3.3–11.9°) with valgus stress. Discussion: Acceptable precision and accuracy may be possible when measuring knee kinematics in early flexion using a non-invasive system; however, we do not believe passive trackers should be mounted with rubber strapping such as was used in this study. Flexing the knee appears to decrease the precision and accuracy of the system. The functions of this new software using image-free navigation technology have many potential clinical applications, including assessment of bony and soft tissue deformity, pre-operative planning, and post-operative evaluation, as well as in further pure research comparing kinematics of the normal and pathological knee

The Blame Game: Water and Sanitation in Kampala’s Urban Slums

Urban poor areas of Kampala, Uganda see severe outbreaks of cholera, malaria, typhoid, bilharzia and other fatal water-borne diseases on an all too regular basis. Many people in the slums still lack safe drinking water and a sanitary living environment and despite efforts, the conditions have not reached or even come close to reaching international or national goals. This research explores various approaches to fixing this vital problem. The objective of this research is to compare various approaches to water and sanitation projects in Kampala’s urban slums. More specifically, the intent is to examine various implementation methods in the water and sanitation sector carried out by local governments, non-governmental organizations, and community-based organizations through the lens of direct and indirect community involvement in projects, and while examining the sustainability of the methods used. The researcher conducted an independent study project (ISP) in Kampala’s slums for a six-week period from the end of March 2008 to the start of May 2008. She conducted many interviews with both community members and key informants of various organizations. These organizations include Kampala City Council, two non-governmental organizations, two community-based organizations, Uganda Water and Sanitation NGO Network, and National Water and Sewerage Corporation. Additionally, she went on many field visits to view projects first-hand. The researcher concludes that the water and sanitation sector in Kampala’s urban slums has a long way to come in order to significantly improve the lives of the urban poor community. While organizations are making promising improvements and innovations on an individual basis, NGOs, CBOs, and the local government could affect many more people if partnerships and open cooperations were formed and fewer fingers were pointed in the someone else’s direction

Domestic well vulnerability to drought duration and unsustainable groundwater management in California's Central Valley

Millions of Californians access drinking water via domestic wells, which are vulnerable to drought and unsustainable groundwater management. Groundwater overdraft and the possibility of longer drought duration under climate change threatens domestic well reliability, yet we lack tools to assess the impact of such events. Here, we leverage 943 469 well completion reports and 20 years of groundwater elevation data to develop a spatially-explicit domestic well failure model covering California's Central Valley. Our model successfully reproduces the spatial distribution of observed domestic well failures during the severe 2012-2016 drought (n = 2027). Next, the impact of longer drought duration (5-8 years) on domestic well failure is evaluated, indicating that if the 2012-2016 drought would have continued into a 6 to 8 year long drought, a total of 4037-5460 to 6538-8056 wells would fail. The same drought duration scenarios with an intervening wet winter in 2017 lead to an average of 498 and 738 fewer well failures. Additionally, we map vulnerable wells at high failure risk and find that they align with clusters of predicted well failures. Lastly, we evaluate how the timing and implementation of different projected groundwater management regimes impact groundwater levels and thus domestic well failure. When historic overdraft persists until 2040, domestic well failures range from 5966 to 10 466 (depending on the historic period considered). When sustainability is achieved progressively between 2020 and 2040, well failures range from 3677 to 6943, and from 1516 to 2513 when groundwater is not allowed to decline after 2020

Modification of Nanodiamonds by Xenon Implantation: A Molecular Dynamics Study

Xenon implantation into nanodiamonds is studied using molecular dynamics. The nanodiamonds range in size from 2-10 nm and the primary knock-on (PKA) energy extends up to 40 keV. For small nanodiamonds an energy-window effect occurs in which PKA energies of around 6 keV destroy the nanodiamond, while in larger nanodiamonds the radiation cascade is increasingly similar to those in bulk material. Destruction of the small nanodiamonds occurs due to thermal annealing associated with the small size of the particles and the absence of a heat-loss path. Simulations are also performed for a range of impact parameters, and for a series of double-nanodiamond systems in which a heat-loss path is present. The latter show that the thermal shock caused by the impact occurs on the timescale of a few picoseconds. These findings are relevant to ion-beam modification of nanoparticles by noble gases as well as meteoritic studies where implantation is proposed as the mechanism for xenon incorporation in pre-solar nanodiamonds

Flight service evaluation of an advanced composite empennage component on commercial transport aircraft. Phase 1: Engineering development

The empennage component selected for this program is the vertical fin box of the L-1011 aircraft. The box structure extends from the fuselage production joint to the tip rib and includes the front and rear spars. Various design options were evaluated to arrive at a configuration which would offer the highest potential for satisfying program objectives. The preferred configuration selected consists of a hat-stiffened cover with molded integrally stiffened spars, aluminum trussed composite ribs, and composite miniwich web ribs with integrally molded caps. Material screening tests were performed to select an advanced composite material system for the Advanced Composite Vertical Fin (ACFV) that would meet the program requirements from the standpoint of quality, reproducibility, and cost. Preliminary weight and cost analysis were made, targets established, and tracking plans developed. These include FAA certification, ancillary test program, quality control, and structural integrity control plans

Medium-term performance and maintenance of SUDS:a case-study of Hopwood Park Motorway Service Area, UK

One of the main barriers to implementing SUDS is concern about performance and maintenance costs since there are few well-documented case-studies. This paper summarizes studies conducted between 2000 and 2008 of the performance and maintenance of four SUDS management trains constructed in 1999 at the Hopwood Park Motorway Service Area, central England. Assessments were made of the wildlife value and sedimentation in the SUDS ponds, the hydraulic performance of the coach park management train, water quality in all management trains, and soil/sediment composition in the grass filter strip, interceptor and ponds. Maintenance procedures and costs were also reviewed. Results demonstrate the benefits of a management train approach over individual SUDS units for flow attenuation, water treatment, spillage containment and maintenance. Peak flows, pond sediment depth and contaminant concentrations in sediment and water decreased through the coach park management train. Of the 2007 annual landscape budget of £15,000 for the whole site, the maintenance costs for SUDS only accounted for £2,500 compared to £4,000 for conventional drainage structures. Furthermore, since sediment has been attenuated in the management trains, the cost of sediment removal after the recommended period of three years was only £554 and, if the design is not compromised, less frequent removal will be required in future

Bio-inspired Sensing and Actuating Architectures for Feedback Control of Civil Structures

Civil structures, such as buildings and bridges, are constantly at risk of failure due to external environmental loads, such as earthquakes or strong winds. To minimize the effects of these loads, active feedback control systems have been proposed but such systems still face numerous challenges which impede their widespread adoption. In order to overcome many of these challenges, inspiration can be drawn from the signal processing and actuating techniques employed by the biological central nervous system to develop a bio-inspired control algorithm. In this study the front-end, signal processing techniques employed by biological sensory systems, and in particular the mammalian auditory system, are drawn upon in order to alleviate computations at the actuation node. This results in a simplistic control law that is a weighted combination of input information about the structure\u27s response such that F   =   WN , where F is the applied control force, W is a pre-determined weighting matrix, and N is a deconstructed representation of the structural response to the applied excitation. There is no empirical solution for deriving an optimal weighting matrix, W , and in this study numerous methods are explored in order to determine values for this matrix that produce the most effective control. These methods include particle swarm optimization, artificial neural networks, and optimal control theory. The various weighting matrices are integrated into the proposed bio-inspired control algorithm and applied in simulation to a five story benchmark structure. These methods are also compared to a traditional linear quadratic regulator (LQR) to gain insight into the overall performance of the bio-inspired control algorithm. Of the three training techniques, the particle swarm optimization technique offers the most effective control which is comparable in performance to the traditional LQR

The design of Flow Injection manifolds to give the best detection limits for methods involving on-line chemical derivatisation Part 2. The spectrophotometric determination of chloride

The optimisation of a flow injection manifold for the spectrophotometric determination of chloride is described. Factors contributing to the baseline noise due to refractive index and reagent absorption effects are removed by a combination of design features. Firstly, a double-line manifold is used; secondly, pulse-dampers and a packed bed reactor are incorporated into the flow lines and thirdly a delay coil is introduced to resolve the valve switching peaks from the determinand peaks. The appropriate conditions for obtaining the maximum sensitivity are found from an off-line experiment and the guidelines established on the basis of the well-stirred tank model for dispersion applied to the design of the operating parameters of flow rate ratio and volume injected. Good agreement between the predicted and experimentally determined values were obtained. The resulting manifold gave a linear calibration from the detection limit (4.5-8.0 ppb) to 2.00 ppm

Elimination of Double Peaks in the Iodimetric Flow Injection Visible Spectrophotometric Determination of Sulphite Using a Single-Channel Manifold

A flow injection method of determining sulphite with amperometric monitoring of iodine using a single-channel manifold in which iodine is formed in the reverse flow injection (rFI) manner and reacts with sulphite dispersing in the normal flow injection (nFI) manner has been adapted for use with visible spectrophotometry. The carrier stream consists of an alkaline solution containing iodate and an excess of iodide: injections of acid and then of acidified sulphite are made. The decrease in the iodine signal (measured at 352 nm) in the presence of sulphite is proportional to the sulphite concentration in the injectate. The alkalinity of the carrier stream was adjusted to reduce the signal widths and to prevent the appearance of double peaks. A rectilinear decrease in signal size (down to ca. 10% of the signal size in the absence of sulphite) was obtained in the range 1 x 10-s_7 x 10-4 M sulphite using a single-channel manifold consisting of 3 m of 0.8 mm bore transmission tubing with a flow-rate of 5 ml min-1 and an injection volume of 15 rd, when the carrier stream was 6.7 x 1 Q-6 Min iodate, 6.7 x 10-2 Min iodide and 3.5 x 1 Q-3 Min sodium hydroxide, and the sample solution was 0.1 M in hydrochloric acid