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Meeting the needs of acute geriatric patients is often challenging, and although evidence shows that older patients need tailored care, it is still unclear which interventions are most appropriate. The objective of this study is to systematically evaluate the hospital-wide acute geriatric models compared with conventional pathways. The design of the study includes hospital-wide geriatric-specific models characterized by components including patient-centered care, frequent medical review, early rehabilitation, early discharge planning, prepared environment, and follow‐up after discharge. Primary and secondary outcomes were considered, including functional decline, activities of daily living (ADL), length-of-stay (LoS), discharge destination, mortality, costs, and readmission. A systematic review and meta-analysis were conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. A total of 20 studies reporting on 15 trials and acutely admitted patients with an average age of 79, complex conditions and comorbidities to acute geriatric-specific pathways (N = 13,595) were included. Geriatric-specific models were associated with lower costs (weighted mean difference, WMD = − $174.98, 95% CI = -$332.14 to − $17.82; P = 0.03), and shorter LoS (WMD = − 1.11, 95% CI = − 1.39 to − 0.83; P

Construction simulation has been an active area of research in the last six decades. Nevertheless, there has been a gap between academia and industry in realizing the capabilities of simulation to support decision-making in construction. One of the well-recognized reasons is the difficulty of undertaking comprehensive simulation studies by construction practitioners, who usually lack sufficient knowledge and skills to adequately build simulation models. Efforts to bridge this gap have been focused on simplifying the computer coding and model implementation stages of construction simulation studies with limited research on the early stage of defining the model and abstracting the system, i.e., conceptual modeling. The conceptual modeling stage is known to be one of the most difficult tasks in a simulation study. Thus, several frameworks to support building conceptual models have been proposed in simulation literature. This study contributes to the research efforts to promote simulation in the construction industry through the adoption of a conceptual modeling framework. It demonstrates the application of the proposed conceptual modeling framework in a case study of piling operations. The findings of this paper reinforced the significance of conceptual modeling by confirming the role of the conceptual model as a communication link between stakeholders. Moreover, the conceptual model was used as a specification document for developing a flexible model that can be replicated in other settings. The use of a documented conceptual model assisted in managing the overall simulation study efficiently, which, in turn, lead to reductions in time and effort for different modeling activities.

Cloud service providers use load balancing algorithms in order to avoid Service Level Agreement Violations (SLAVs) and wasted energy consumption due to host over- and under-utilization, respectively. Load balancing algorithms migrate VMs between hosts in order to balance host loads. Any Virtual Machines (VMs) that are migrated experience performance degradation which results in lower Quality of Service (QoS) and can possibly result in SLAVs. Hence, an optimal load balancing method should reduce the number of over- and under-utilized hosts with a minimal number of VM migrations. One of the metrics used previously in the literature for evaluating load balancing stated that it equally considered SLAVs caused by both over-utilized hosts and migrations. However, in this paper, we show that, in fact, this metric values keeping the number of migrations low at the expense of an increased number of over-utilized hosts. This disparity is demonstrated by simulation of Google, PlanetLab and Azure data sets in CloudSim. This metric may suit public cloud providers which are focused on minimizing SLAVs and keeping energy costs low, but does not consider the QoS of customer VMs. We propose an alternative metric that considers QoS for the VMs. This alternative metric considers not only performance loss during migration, but also performance degradation due to host over-utilization. Private cloud providers, e.g., IT services within large organizations, often value the performance of their “customer” VMs, i.e., the QoS their organization receives, as well as traditional cloud provider costs, i.e., energy and SLAV costs. Hence, our alternative metric would be more appropriate in these scenarios. We compare and contrast load balancing methods using both the existing, biased metric and our new alternative metric.

BACKGROUND This multicentre cohort study investigates the effect of smoking on the outcome of rotator cuff repair (RCR), with attention to age at presentation for surgery, pre-operative and post-operative pain and function and intra-operative findings. METHODS Patient information was collected pre-operatively, including Flex Shoulder Function (Flex SF) and visual analogue scale pain, then at 6 months, 1, 2 and 5 years post-operatively. Intra-operative technical data were collected by the operating surgeon. Current smokers were classified by daily cigarette consumption. RESULTS A total of 1383 RCRs in as many patients were included with an 84% 5-year follow-up. Smokers were on average 6.7 years younger than non-smokers (51.8 vs. 58.5, P

Simulation modelling has been utilised as a decision-support tool for different production systems. However, simulation uptake in construction is lagging due to several challenges such as the exten...

Planning of operations, such as routing of vehicles, is often performed repetitively in rea-world settings, either by humans or algorithms solving mathematical problems. While humans build experience over multiple executions of such planning tasks and are able to recognize common patterns in different problem instances, classical optimization algorithms solve every instance independently. Machine learning (ML) can be seen as a computational counterpart to the human ability to recognize patterns based on experience. We consider variants of the classical Vehicle Routing Problem with Time Windows and Capacitated Vehicle Routing Problem, which are based on the assumption that problem instances follow specific common patterns. For this problem, we propose a ML-based branch and price framework which explicitly utilizes those patterns. In this context, the ML models are used in two ways: (a) to predict the value of binary decision variables in the optimal solution and (b) to predict branching scores for fractional variables based on full strong branching. The prediction of decision variables is then integrated in a node selection policy, while a predicted branching score is used within a variable selection policy. These ML-based approaches for node and variable selection are integrated in a reliability-based branching algorithm that assesses their quality and allows for replacing ML approaches by other (classical) better performing approaches at the level of specific variables in each specific instance. Computational results show that our algorithms outperform benchmark branching strategies. Further, we demonstrate that our approach is robust with respect to small changes in instance sizes.

BackgroundImpetigo is a common and contagious bacterial skin infection, affecting children worldwide but it is particularly prevalent in deprived communities. In New Zealand widespread prescribing of the topical antibiotic fusidic acid had led to an increase in antimicrobial resistance of Staphylococcus aureus. Alternative treatments are urgently being sought and as impetigo is a superficial infection, it has been suggested that topical antiseptics such as hydrogen peroxide or simple wound care alone may treat impetigo while avoiding the risk of increased antimicrobial resistance.MethodsThis protocol for a non-inferiority, single-blind randomised controlled trial compares topical fusidic acid with topical hydrogen peroxide and with simple wound care in the treatment of childhood impetigo. Participants are randomised to one of the three treatments for five days and the primary outcome is clinical improvement. This is assessed through paired photographs analysed by graders blinded to treatment arm. The trial is based in school health clinics in an urban centre in New Zealand. Comparison of antimicrobial resistance patterns pre- and post-treatment is also performed.DiscussionSpecial note is made of the need to involve the communities most affected by impetigo in the design and implementation of the clinical trial in order to recruit the children most in need of safe and effective treatments.Trial registration: Australian New Zealand Clinical Trials Registry (ANZCTR) 12616000356460

We implement jackknife model averaging (JMA) and a new prediction technique—hybrid-boost model averaging (HbMA)—to a surgical dataset that includes categorical explanatory variables. The model requirements for HbMA are different to that for JMA. HbMA generally does not require decent models to be included in the model average. However, the utility of HbMA is limited by the possibility of multiple solutions for the HbMA weights. Both model averaging approaches are comparable under the appropriate conditions. Among all the model averages considered, the best jackknife model average gives slightly better predictions of the surgery durations than the best hybrid-boost model average when evaluated on our surgical dataset. Finally, we discuss several methods that may further improve the performance of HbMA.

The on-time completion of patient transits can be identified as a bottleneck for the efficiency of health care services in major New Zealand hospitals. Delayed transits of patients between wards and treatment or diagnostic facilities lead to increasing waiting times at clinics and inefficient resource utilization (e.g. surgery teams) as appointment times are not met. Patient transits are carried out by orderlies, but in some cases require the assistance of a nurse. Ad-hoc dispatching of staff members, nurses and orderlies, to transits has been identified as one major source for delays currently observed in the system. To address this issue we present automated, optimized dispatching algorithms for staff members performing those transits. To develop these algorithms, a network formulation of the problem is introduced that is strongly related to classical vehicle routing problem with semi-soft time windows. However, the need to synchronize the routes of staff members of different types (nurses and orderlies) adds a whole new layer of complexity to the problem, as routes cannot be assessed independently. We present a set of algorithms with varying complexity, ranging from simple heuristics to the use of critical path methods to combine mixed integer formulations for the separated orderly and nurse problems. To address a transit service’s stochasticity, volatility and the resulting need for constant re-optimization, we embed the optimization algorithms in a discrete event simulation to evaluate their performance under realistic circumstances.

The design of generic models, or generic building blocks, for health care operations has been discussed in depth and identified as one of the grand challenges for researchers in the field of Modeling and Simulation. In this paper we provide an investigative basis for answering recently raised research questions for a specific sub-domain of health care facilities and a specific Modeling and Simulation paradigm, i.e. Discrete Event Simulation Models of Emergency Departments. We perform a detailed analysis of a large set of published Emergency Department models. This analysis is executed following a structured conceptual modeling framework to ensure the coverage of key conceptual modeling aspects: objectives; input scenarios; output definitions, i.e. commonly used performance indicators; structural components such as physical resources and human resources (including expertise and skill levels); patient classifications (arrival modes, triage grades, complaint categories); patient pathways including triage, treatment (which possibly includes resuscitation or special care) and admission phases; and organizational structures including control policies. The resulting collection and classification of modeling archetypes are used as the basis for an initial generic modeling toolkit for Emergency Department operations. Thereby, the modeler is guided through the main steps of conceptual modeling of Emergency Departments and generic building blocks for each step are provided. The paper concludes with a discussion on the applicability and benefits of the resulting GEDMod framework along with the potential to combine the toolkit into a single generic Emergency Department model.

Healthcare processes contain various complexities which make them difficult to model. These include: multiple-participant activities with flexible resourcing; dynamic task priorities; hierarchical skill levels of resources; and regular task pre-emption. Deciding which task in a care pathway a clinician next performs directly impacts on the performance of the healthcare process. The Hierarchical Control Conceptual Modeling (HCCM) approach has recently been proposed by Furian et al. [1] to provide a conceptual modelling framework purpose-built to explicitly model the decision-making structure in complex systems. Existing software packages for Discrete Event Simulation (DES) have been designed for conceptual models that consist of systems of queues. In particular, the lack of a module specifically designed to account for HCCM’s control structure makes the implementation of a HCCM conceptual model in an off-the-shelf simulation package problematic. This research applies the HCCM framework to a real-world Cytology lab (with complex decision making for task allocations) and demonstrates how the resultant conceptual model can be implemented within an off-the-shelf healthcare simulation package (Flexsim HC). The primary goal is a proof-of-concept that the control mechanism, particular to the HCCM framework, can be implemented using such a simulation package.

In scheduling theory and practise for parallel computing, representing a program as a task graph with communication delays is a popular model, due to its general nature, its expressiveness and relative simplicity. Unfortunately, scheduling such a task graph on a set of processors in such a way that it achieves its shortest possible execution time ( P | pred, c ij | C max in α | β | γ notation) is a strong NP-hard optimization problem without any known guaranteed approximation algorithm. Hence, many heuristics have been researched and are used in practise. However, in many situations it is necessary to obtain optimal schedules, for example, in the case of time-critical systems or for the evaluation of heuristics. Recent years have seen some advances in optimal algorithms for this scheduling problem, based on smart exhaustive state-space search or MILP (Mixed Integer Linear Programming) formulations. This paper proposes a novel approach based on SMT (Satisfiability Modulo Theory). We propose an elegant SMT formulation of the scheduling problem that only needs one decision variable and is very compact and comprehensible in comparison to the state-of-the-art MILP formulations. This novel optimal scheduling approach is extensively evaluated in experiments with more than a thousand task graphs. We perform experimental comparison with the best known MILP formulations, with attempts to further improve them, and deeply analyse the behaviour of the different approaches with respect to size, structure, number of processors, etc. Our proposed SMT-based approach in general outperforms the MILP-formulations and still possesses great potential for further optimization, from which MILP formulations have benefited in the past.

Summary 1.Mark-recapture distance sampling surveys with two independent observers are widely used to estimate wildlife population abundance. The analysis relies on accurate identification of duplicate sightings common to both observers, and correct judgments of group size, both of which are hard to achieve for species that exhibit complex grouping patterns. 2.In this paper, we examine the impact of these sources of uncertainty on bias and precision of abundance estimates, using a case study of 22 aerial surveys of common dolphins (Delphinus delphis) in the Hauraki Gulf, New Zealand. We develop a novel probabilistic method to identify duplicate observations, and account for various sources of uncertainty using a simulation-intensive approach. 3.For our case study, identifying duplicates using reasonable but arbitrary thresholds of time and angle discrepancies created a range of abundance estimates differing by up to 20%, whereas our novel threshold-free probabilistic analysis returned an estimate roughly central to this range. Uncertainty in group size made a smaller impact of up to 5% on abundance estimates. All analysis choices returned similar values for the coefficient of variation, from 20-23%. 4.Generating robust estimates of abundance, and accounting for all associated sources of uncertainty, is critical for informing conservation management. Our novel approach provides a way to eliminate arbitrary decisions associated with mark-recapture distance sampling, and account for a wider range of uncertainties. Our method allows for the reliable application of mark-recapture distance sampling to a wider range of terrestrial and marine species, and will be a useful tool for producing robust abundance estimates for species that exhibit complex grouping patterns. This article is protected by copyright. All rights reserved.

Discrete-Event Simulation (DES) is an event-driven simulation approach in which a real dynamic process is imitated as it progresses over time. It has been recognized as a powerful technique for the quantitative analysis of complex construction operations. However, current DES modelling strategies/frameworks implicitly rely on queuing structures which are too rigid to easily describe systems with complex behaviour common in construction, e.g., multi-tasking resources and/or role changes of entities. Queuing networks are one of the most common elements of DES systems and have been used to model a wide range of problems, but they lack the generality to easily model the complex decision mechanisms required to, e.g., efficiently multi-task or dynamically determine the best role for an entity. This research proposes a new modelling approach for construction that replaces Queue-Based (QB) DES, with its implicit queuing network control, with Non-Queue-Based (NQB) DES that explicitly defines the decision mechanisms of a model. It utilises a new conceptual modelling paradigm for simulation, Hierarchical Control Conceptual Modelling, which was developed to address similar issues with control mechanisms in health care simulation. This new approach is especially beneficial for the construction industry where determining effective decision making mechanisms is of significant importance for optimising, e.g., logistics and resource utilisation. This research investigates the benefits of the proposed approach for DES models in construction by investigating three earthmoving case studies. Although the scope of this research is limited to DES modelling in construction, the outcomes of the proposed NQB paradigm in construction translate to other domains that utilise DES for solving complex problems.

Background This study is a collation of baseline demographic characteristics of those presenting for rotator cuff repair in New Zealand, and exploration of associations with preoperative function and pain. Data were obtained from the New Zealand Rotator Cuff Registry; a multicentre, nationwide prospective cohort of rotator cuff repairs undertaken from 1 March 2009 until 31 December 2010. Methods A total of 1383 patients were included in the study. This required complete demographic information, preoperative Flex-SF (functional score) and pain scores. Following univariate analysis, a multivariate model was used. Results The average age was 58 years (69% males and 11% smokers). New Zealand Europeans made up 90% and Maori 5%. The average preoperative Flex-SF was significantly lower (poorer function) in those over 65 years, females, smokers and Maori, in the non-dominant patients, using a multivariate model. Average preoperative pain scores were significantly worse (higher scores) in females, Maori, Polynesians, smokers, using a multivariate model. Conclusion This is the largest reported prospective cohort of patients presenting for rotator cuff surgery. Results can be used to understand the effect of rotator cuff tears on the different patients, for example Maori patients who are under-represented, present younger, with more pain and poorer function.

During an expansion of the General Medicine (GM) department at Waitakere Hospital, a new roster was required for its teams. Patients being transferred to another hospital due to uneven patient workloads between the teams were identified as an issue that could be addressed by an improved roster. A more even distribution of patients among the teams is desirable because it is fairer for the staff and it also improves the continuity of care for patients. Continuity of care is improved by balanced workloads because fewer patients need to be transferred from teams with high workloads. A novel rostering technique, using a mixed integer programme (MIP), which uses past data on patient admissions to track team workloads, was implemented. This allowed multiple rosters for different configurations of admitting teams to be created and evaluated against past data traces, in terms of the difference in workloads of the teams and estimated ward occupancies. The best performing of the constructed rosters reduced the median difference in workload between the team with the most patients and the team with the fewest from 14.5 to 12.5 (13.8% reduction) for the data traces considered, when compared with a roster from an internal rostering group. Waitakere Hospital has put this roster in place and has observed a reduction in the variation in workload between the teams, with fewer patients being transferred to other hospitals due to high team workloads. These improvements cannot be solely attributed to rostering improvements, as other factors such as an increase in the number of inpatient teams have also contributed. However, the generation and evaluation of multiple different rosters via MIP was central to the process that determined the final configuration of the GM department.

This paper presents a case study of research conducted to improve the delivery of treatment to high priority cancer patients. The authors present a modelling framework that uses time-stamp data collected by the North Shore Hospital IT systems as “business as usual”, to describe the patient journey through the cancer-care process. A simulation process is developed that uses this data to estimate the service's performance under current operating practices, and enables “what-if” analysis to identify where changes to current practice can most effectively be applied, ensuring the investment of additional resource can be targeted at the steps of the patient pathway where it can result in the greatest improvement. The process is illustrated using the Breast Cancer stream as a case-study, for the initial study period (July 2013 to June 2014), with a follow-up analysis presented briefly for the 3 months from July to the end of September 2014.

Mechanical and structural properties of ovine rumen tissue have been determined using uniaxial tensile testing of tissue from four animals at five rumen locations and two orientations. Animal and orientation did not have a significant effect on the stress-strain response, but there was a significant difference between rumen locations. Histological studies showed two orthogonal muscle layers in all regions except the reticulum, which has a more isotropic structure. A quasi-linear viscoelastic model was fitted to the relaxation stage for each region. Model predictions of the ramp stage had RMS errors of 13–24% and were within the range of the experimental data.

Energy consumption constitutes a significant proportion of data centers' operational costs. Furthermore, the establishment of large scale Cloud data centers due to the fast growth of utility-based IT services made the energy usage of data centers a concern. Cloud data centers use load balancing algorithms to allocate their physical resources (CPU, memory, hard disk, network bandwidth) efficiently on demand and hence optimize their energy consumption. In the load balancing process, some Virtual Machines (VMs) are selected from over-or under-utilized physical hosts and these VMs are migrated, while live and running, to other hosts. This live migration can result in Service Level Agreement Violations (SLAVs) and consequently low Quality of Service (QoS). Thus, in this paper, we propose an energy aware VM selection policy to minimize the number of migrations and consequently decrease SLAVs. Load balancing has three stages: a) Detecting over-and under-utilized hosts; b) Selecting one or more VMs for migration from those hosts; c) Finding destination hosts for the selected VMs. The focus of this research is on the VM selection stage of CPU load balancing. Our proposed VM selection algorithm considers CPU utilization of the VMs on each host and any linear correlation between the CPU usage of the VMs. The algorithm was evaluated on two different real Cloud data sets provided by the CoMon project and Google. Its performance was compared to our benchmark policy that only considers minimum migration time for VM selection. The results showed that our proposed algorithm decreases SLAVs by 66%, ESV (SLAVs × energy consumption) by 64% and the number of "re over-utilized" hosts by 81% when the CPU usage of VMs in a data set are highly correlated (e.g., as in the Google data set).

Tactile feedback in recent decades has allowed humans to receive information through technology beyond traditional visual and auditory senses. Lateral skin stretch has the potential to be a mode of tactile feedback, reliably enabling the perception of directional cues through the use of a single actuator. Experiments were conducted to explore sensitivity to skin stretch on nine locations on the human lower leg. Thirty-two stimuli were presented to subjects, exploring effects of displacement (from 0.2-2.0 mm) and speed (from 0.5-4.0 mm/s) on the perception of left and right directions. Higher accuracy came from stimuli having higher displacements and speeds. Three of the locations: soleus, calcaneal tendon (upper), and fibularis longus (lower) all had a mean accuracy of at least 85 percent and are suitable locations for a skin stretch tactile feedback device.

The goal of construction system modelling is to improve construction work performance by tracking the dynamic behaviour of construction systems. Discrete-Event Simulation (DES) has been suggested as a supporting tool for management decision-making in order to capture the dynamic complexity of construction projects. However, the limitations of DES in modelling influential factors such as the individual and emergent behaviour of system entities have led to the combined use of Agent-based Simulation (ABS) and DES. This paper provides an overview of DES and ABS applications in construction, and then discusses rationale for integrating DES and ABS from the conceptual stage onwards. Furthermore, a hybrid DES-ABS conceptual framework is introduced and the challenges of this type of hybrid simulation model are explained.

Aim This study aims to describe the microbiology of middle ear fluid (MEF) in a cohort of children vaccinated with Streptococcus pneumoniae conjugate vaccine (PCV7) having ventilation tube insertion. Nasopharyngeal (NP) carriage of otopathogens in these children is compared with children without history of otitis media. Methods Between May and November 2011, MEF and NP samples from 325 children aged

Conventional smoothing over complicated coastal and island regions may result in errors across boundaries, due to the use of Euclidean distances to measure interpoint similarity. The new Complex Region Spatial Smoother (CReSS) method presented here uses estimated geodesic distances, model averaging, and a local radial basis function to provide improved smoothing over complex domains. CReSS is compared, via simulation, with recent related smoothing techniques, Thin Plate Splines (TPS), geodesic low rank TPS (GLTPS), and the Soap film smoother (SOAP). The GLTPS method cannot be used in areas with islands and SOAP can be hard to parameterize. CReSS is comparable with, if not better than, all considered methods on a range of simulations. Supplementary materials for this article are available online.

Periprosthetic osteolysis in the retroacetabular region with cancellous bone loss is a recognized phenomenon in the long-term follow-up of total hip replacement. The effects on load transfer in the presence of defects are less well known. A finite element model incorporating a retroacetabular defect behind a cementless component was validated against a 4th generation sawbone pelvis. Computational predictions of surface strain and von Mises stresses were closely correlated to experimental findings. The presence of a cancellous defect increased von Mises stress in the cortical bone of the medial wall of the pelvis. At a load of 600 N this was under the predicted failure stress for cortical bone. Increases in the cup size relative to the acetabulum caused increased stress in the cortical bone of the lateral wall of the pelvis, adjacent to the acetabulum. We are confident that our modeling approach can be applied to patient specific defects to predict pelvis stress with large loads and a range of activities.

Background: Rotator cuff-tear arthropathy has traditionally represented a challenge to the shoulder arthroplasty surgeon. The poor results of conventional total shoulder arthroplasty in rotator-cuff-deficient shoulders due to glenoid component loosening have led to hemiarthroplasty being the traditional preferred surgical option. Recently, reverse total shoulder arthroplasty has gained increasing popularity because of a clinical perception of an improved functional outcome, despite the lack of comparative data. The aim of this study was to compare the early functional results of hemiarthroplasty with those of reverse shoulder arthroplasty in the management of cuff-tear arthropathy. Methods: The results of 102 primary hemiarthroplasties for rotator cuff-tear arthropathy were compared with those of 102 reverse shoulder arthroplasties performed for the same diagnosis. Patients were identified from the New Zealand Joint Registry and matched for age, sex, and American Society of Anesthesiologists (ASA) scores. Oxford Shoulder Scores (OSS) collected at six months postoperatively as well as mortality and revision rates were compared between the two groups. Results: There were fifty-one men and fifty-one women in each group, with a mean age of 71.6 years in the hemiarthroplasty group and 72.6 years in the reverse shoulder arthroplasty group. The mean OSS at six months was 31.1 in the hemiarthroplasty group and 37.5 in the reverse shoulder arthroplasty group. At the time of follow-up, there were nine revisions in the hemiarthroplasty group and five in the reverse shoulder arthroplasty group. No difference in mortality rate was seen between the two groups. Conclusions: In this unselected population with rotator cuff-tear arthropathy, controlled for age, sex, and ASA score, reverse shoulder arthroplasty resulted in a functional outcome that was superior to that of hemiarthroplasty. Longer-term follow-up is needed to confirm these findings. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Bone mineral density (BMD) in the proximal tibia decreases after TKA and is believed to be a factor in implant migration and loosening. Unicompartmental knee arthroplasty (UKA) is a less invasive procedure preserving knee compartments unaffected by degeneration. Finite element studies have suggested UKA may preserve BMD and that implants of differing stiffnesses might differentially affect BMD but these notions have not been clinically confirmed.We therefore asked whether (1) proximal tibial BMD decreases after UKA, and (2) a cemented metal tibial component with a mobile polyethylene (PE) bearing would have greater BMD loss than a cemented PE tibial component.We prospectively followed 48 patients who underwent 50 UKAs using one of two implants: one with a cemented metal tibial baseplate and a mobile PE insert (n = 26) and one with a cemented all-PE tibial component (n = 24). In followup we assessed pain and function (Oxford Knee Score, SF-12, The Knee Society Score(©)) and radiographs. BMD changes were assessed using quantitative CT osteodensitometry performed postoperatively and at 1 and 2 years after the index procedure.Mean cancellous BMD decreased 1.9% on the medial side and 1.1% on the lateral side. Mean cortical BMD was static, decreasing 0.4% on the medial side and increasing 0.5% on the lateral side. The greatest observed difference between implants for any region was 3.7%. There were no differences in pain or functional outcome scores.BMD was preserved 2 years after UKA with no major differences seen between implant types.

We are using full-scale three dimensional numerical model of the Rotorua geothermal system to generate temperature and pressure time series in model blocks where a surface features is located. The Pearson correlation factors between the time series, rainfall, and recorded temperature variations in surface features are calculated which allows us to determine the contribution of these variations to the behaviour of the surface features for blocks at different depths. This is enable us to determine some of the main controls of the behaviour of such geothermal surface features and thus what should be included in a predictive model (e.g. rainfall and bi-annual production and reinjection rates).

Study design Blinded radiographic analysis of CT scans reformatted for precise lumbar spinous process (LSP) measurement.

We present a nonlinear integer programming formulation for fitting a spline-based regression to two-dimensional data using an adaptive knot-selection approach, with the number and location of the knots being determined in the solution process. However, the nonlinear nature of this formulation makes its solution impractical, so we also outline a knot selection heuristic inspired by the Remes Exchange Algorithm, to produce good solutions to our formulation. This algorithm is intuitive and naturally accommodates local changes in smoothness. Results are presented for the algorithm demonstrating performance that is as good as, or better than, other current methods on established benchmark functions.

Optimization and heuristic methods for the design of medium to large storage area networks (SANs) are in the early stages of development, but are required if large clustered storage systems are to become a viable alternative to expensive monolithic storage. We present here a new mixed-integer formulation for optimal design of a storage area network. Our formulation models the Single-edge Core-Edge topology. Using a testbed of medium to large problems, we compare the solution times for our new formulation to the current benchmark in the literature-our formulation solves in significantly less time with an off-the-shelf optimization software package. We also generate problem-specific cuts to further reduce the solution time for our formulation. An algorithm, which includes an integer programming subproblem, is described for generating some of these cuts. For all test problems, the cuts yield a further reduction in the solution time.

Little is known about tibial bone remodeling with TKA and its clinical relevance. We performed a randomized clinical trial to compare tibial bone density changes in cemented components with different bearing designs. Bone density changes were assessed using quantitative computed tomography (qCT)-assisted osteodensitometry. Twenty-eight rotating-platform and 26 fixed-platform cemented TKAs were included. The nonoperated contralateral side was used as a control. CT scans were performed postoperatively and 1 year and 2 years after the index operation. Cancellous bone density loss (up to 12.6% at 2 years) was observed in all proximal tibial regions in both cohorts. In contrast, we found lower cortical bone density loss (up to 3.6% at 2 years). We found no differences in bone loss between fixed- and rotating-platform implants. The decrease of cancellous bone density after TKA suggests stress transfer to the cortical bone.

Located on the Caribbean coast of Mexico's Yucatan Peninsula, the village of Cancun was radically transformed when mass tourism development began there in the early 1970s. Cancun and the surrounding “Maya Riviera” quickly became a wildly popular tourism destination offering a variety of cultural experiences, including visits to ancient Maya archaeological sites. Now, some of those archaeological sites are in danger of being “loved to death,” while others are only just beginning to appear on the tourist radar. There is increasing pressure to balance tourist accessibility with conservation of the ancient buildings and to find a balance that incorporates architectural and ecological conservation, management of the tourist procession through the site, and effective interpretation of the site to enhance the visitor experience. Sites need to be presented within historical, temporal, and geographical contexts, and tourists must be educated about the host region and local indigenous cultures to enhance the tourism experience and encourage tourist behaviors that promote sustainability at the site.

The number of periprosthetic fractures following total hip arthroplasty (THA) is increasing. There is, however, limited data on the functional outcome following these injuries. We analyzed functional outcome for revision THA following periprosthetic fracture, and compared this to the outcome of elective revision THA performed for aseptic loosening.232 patients undergoing revision THA for femoral fracture were identified from the New Zealand National Registry. Functional outcome was measured using the Oxford 12 hip score (OHS). A reference group of 232 patients undergoing elective revision THA was selected and matched for age and sex.Outcome was worse following revision THA for periprosthetic fracture than in reference patients (mean OHS: 29 vs. 24, p = 0.006). A higher 6-month mortality rate was seen in periprosthetic fracture patients (7.3% vs. 0.9%, p0.001), along with a higher likelihood of re-revision (7.3% vs. 2.6%, p = 0.06).This large comparative series of periprosthetic fractures following THA shows that patients with periprosthetic fracture have poorer functional outcome and higher death rates than patients undergoing revision THA for aseptic loosening.

There are many developments for offshore renewable energy around the United Kingdom whose installation typically produces large amounts of far-reaching noise, potentially disturbing many marine mammals. The potential to affect the favorable conservation status of many species means extensive environmental impact assessment requirements for the licensing of such installation activities. Quantification of such complex risk problems is difficult and much of the key information is not readily available. Expert elicitation methods can be employed in such pressing cases. We describe the methodology used in an expert elicitation study conducted in the United Kingdom for combining expert opinions based on statistical distributions and copula-like methods.

In this paper we address the problem of optimal network design for a storage area network. We consider the Core-Edge reference topology and present two formulations for the Core-Edge storage area network design problem. One formulation excludes explicit host/device connections to the edge (as is common in currently available heuristics), the other includes these connections to allow the modeling of multiple disjoint paths between hosts and devices. These formulations include generic component types to reduce the number of constraints and variables, with the properties of these components being determined as part of the solution process. The size of the formulation is further reduced by a preprocessing method that removes suboptimal switches and links from consideration. We test our formulations on a randomly generated set of problems, all of which are of a size consistent with those encountered in industry. We generate solutions using our two formulations for all test problems in good time. Finally we apply a relaxation of one of our formulations to re-configure the Cecil back-end network, which is currently used across the University of Auckland. We present two designs for the re-configured network to significantly increase reliability and scalability.

Five hundred orthopaedic surgeons and 336 anaesthetists were surveyed to assess current UK attitudes towards transfusion practice following arthroplasty surgery. Seventy-two percent of surgeons and 73% of anaesthetists responded to the survey. In an uncomplicated patient following total hip arthroplasty, 53.2% of surgeons and 63.1% of anaesthetists would transfuse at or below a haemoglobin (Hb) level of 8 g/dL. Surgeons tended to be more aggressive in their attitudes, with a mean transfusion threshold of 8.3 g/dL compared to 7.9 g/dL for anaesthetists (p

Background: Nonoperative treatment of idiopathic clubfoot has become increasingly accepted worldwide as the initial standard of care. The Ponseti method has become particularly popular as a result of published short and long-term success rates in North America. The purpose of the current study was to examine the early rate of clubfoot recurrence following the use of the Ponseti treatment method in a New Zealand population and to analyze patient characteristics to identify factors predictive of recurrence. Methods: Fifty-one consecutive babies with a total of seventy-three clubfeet treated by the Ponseti technique were followed prospectively for a minimum of two years from the start of treatment. Recurrence, defined as the need for any subsequent operative treatment, was analyzed with respect to the severity at presentation, the time of presentation, the number of casts needed to obtain the initial correction, any family history of clubfoot, ethnicity, and the compliance with postcorrection abduction bracing. Recurrence was classified as minor, defined as requiring a tendon transfer or an Achilles tendon lengthening, or major, defined as requiring a full posterior or posteromedial surgical release to achieve a corrected plantigrade foot. Results: Twenty-one (41%) of the fifty-one patients had a recurrence, which was major in twelve of them and minor in nine. The parents of twenty-six babies (51%) complied with the abduction bracing protocol, and only three of these children had a major recurrence. Compliance with abduction bracing was associated with the greatest risk reduction for recurrence (odds ratio, 0.2; p = 0.009). When the parents had not complied with the bracing protocol, the patient had a five times greater chance of having a recurrence. With the numbers studied, no significant relationships were found between recurrence and the severity at presentation, the time of presentation, the number of casts needed to obtain correction, ethnicity, or a family history of clubfoot. Conclusions: Compliance with the postcorrection abduction bracing protocol is crucial to avoid recurrence of a clubfoot deformity treated with the Ponseti method. When the parents comply with the bracing protocol, the Ponseti method is very effective at maintaining a correction, although minor recurrences are still common. When the parents do not comply with the bracing protocol, many major and minor recurrences should be expected. Level of Evidence: Prognostic Level II. See Instructions to Authors for a complete description of levels of evidence.

The concept of using distributed computing to supply video games to end users has been growing in popularity. Internet cafes are one potential application for this concept. We consider a cloud-based model for Internet cafes where servers provide virtual machines with different specifications in order to meet different kinds of user demand (web browsing, low end gaming, medium end gaming, and high end gaming). In an Internet cafe, users arrive throughout the day with different demands and different durations for which they stay. Given the user demand over time and a fixed hardware set-up of servers, the task then consists of choosing which users to accept and how to allocate the accepted users to the servers in order to maximize the total profit of the Internet cafe. We formulate an integer programming model for computing an optimal choice of users to accept together with an efficient allocation of accepted users to servers. Computational results show that, when allocating users efficiently, using a cloud-based setting with servers providing virtual machines that exactly meet the users' demands can greatly improve resource efficiency in Internet cafes compared to classical zoning models that use desktop computers. At the same time, the total profit obtained from accepting users can be improved significantly due to the added flexibility when using an optimized user acceptance strategy.

As of 2010 data centers use 1.5% of global electricity production and this is expected to keep growing [1]. There is a need for a near real-time power consumption modeling/monitoring system that could be used at scale within a Software Defined Data Center (SDDC). The power consumption models and information they provide can then be used to make better decisions for data center orchestration, e.g., whether to migrate virtual machines to reduce power consumption. We propose a scalable system that would 1) create initial power consumption models, as needed, for data center components, and 2) could be continually refined while the components are in use. The models will be used for the near real-time monitoring of power consumption, as well as predicting power consumption before and after potential orchestration decisions. The first step towards this goal of whole data center power modeling and prediction is to be able to predict the power consumption of one server effectively, based on high level utilization statistics from that server. In this paper we present a novel method for modeling whole system power consumption for a server, under varying random levels of CPU utilization, with a scalable random forest based model, that utilizes statistics available at the data center management level.

Background Recent literature has shown that Propionibacterium acnes can be cultured from superficial and deep layers of the shoulder. Our aims were to assess the rate of P. acnes colonization in patients undergoing primary shoulder arthroplasty, to identify patient-related risk factors, and to evaluate the efficacy of our perioperative antisepsis protocol. Methods Thirty consecutive patients undergoing primary shoulder arthroplasty were included in our study. Swabs were taken perioperatively (4 superficial and 2 deep wound swabs) and analyzed quantitatively for P. acnes . Cefazolin minimum inhibitory concentration was determined for P. acnes isolates from positive deep cultures. Results Twenty-two patients (73%) had positive cultures for P. acnes . Male gender ( P = .024) and presence of hair ( P = .005) had significantly higher rates of P. acnes superficial cultures. Subjects with positive superficial P. acnes cultures ( P = .076) and presence of hair with a history of steroid injection ( P = .092) were more likely to have deep P. acnes –positive cultures, but this was not statistically significant. Local topical antisepsis measures did not eradicate P. acnes ( P = .12). Mean cefazolin minimum inhibitory concentration for P. acnes was 0.32 μg/mL. Conclusion P. acnes is commonly isolated from the skin and deep surgical wounds of patients undergoing primary total shoulder arthroplasty who have not had previous shoulder surgery. Male gender and presence of hair were significant risk factors for P. acnes colonization. Perioperative local topical antisepsis and cefazolin administration were not effective in eliminating P. acnes colonization.

The problem of designing fibre-optic networks for local-access telecommunications generates (at least) three non-trivial subproblems. In the first of these subproblems one must determine how many fibre-optic cables (fibres) are required at either end of a street. In the next subproblem a minimum-cost network must be designed to support the fibres. The network must also provide distinct paths from either end of the street to the central exchange(s). Finally, the fibre-optic cables must be placed in protective covers. These covers are available in a number of different sizes, allowing some flexibility when covering each section of the network. In this paper we describe a dynamic programming (DP) formulation for finding a minimum-cost (protective) covering for the network (the third of the subproblems). This problem is a generalised set covering problem with side constraints and is further complicated by the introduction of fixed and variable welding costs. The DP formulation selects covers along each arc (in the network), but cannot exactly model the fixed costs and so does not guarantee optimality. We also describe an integer programming (IP) formulation for assessing the quality of the DP solutions. The cost of the networks constructed by the IP model is less than those designed using the DP model, but the saving is not significant for the problems examined (less than 0.1%). This indicates that the DP model will generally give very good solutions. Furthermore, as the problem dimensions grow, DP gives significantly better solution times than IP.

Background: Periprosthetic bone remodelling is an important issue in total hip arthroplasty, which can compromise long-term outcomes. The aim of this study was to evaluate bone remodelling of the proximal femur with an uncemented hydroxyapatite-coated taper stem. Methods: Twenty-three patients (27 hips) were included in this study. The mean age of the patients at the index operation was 57.2 years. There were 15 men and 8 women. Bone remodelling was assessed with quantitative computed tomography and the clinical outcome determined using the Harris Hip Scores. The mean preoperative Harris Hip Score was 38 points and at the 1-year follow up, it was rated 96 points. All hips were radiologically stable. Results: At the 1-year follow up, we found a greater bone-density loss of the cancellous bone (ranging from 16.7 to 28.2%) compared with the cortical bone (ranging from 5.3 to 7.8%). A strong correlation was found between the low density of the cortical bone at the index operation and a higher loss of bone density at the follow up. Conclusion: The newly designed tapered stem showed good clinical and radiological outcomes with a proximal femoral bone loss that compares favourably with other studies.

The object of this study was to develop a method to assess the accuracy of an image-free total knee replacement navigation system in legs with normal or abnormal mechanical axes. A phantom leg was constructed with simulated hip and knee joints and provided a means to locate the centre of the ankle joint. Additional joints located at the midshaft of the tibia and femur allowed deformation in the flexion/extension, varus/valgus and rotational planes. Using a digital caliper unit to measure the coordinates precisely, a software program was developed to convert these local coordinates into a determination of actual leg alignment. At specific points in the procedure, information was compared between the digital caliper measurements and the image-free navigation system. Repeated serial measurements were undertaken. In the setting of normal alignment the mean error of the system was within 0.5°. In the setting of abnormal plane alignment in both the femur and the tibia, the error was within 1°. This is the first study designed to assess the accuracy of a clinically-validated navigation system. It demonstrates in vitro accuracy of the image-free navigation system in both normal and abnormal leg alignment settings.

This paper describes the development and implementation of an optimization model used to resolve disruptions to an operating schedule in the rail industry. Alterations to the existing train timetable and crewing roster are made simultaneously in real time--previous treatments in the literature have always decoupled these two problems and solved them in series. An integer programming model is developed that constructs a train timetable and crew roster. This model contains two distinct blocks, with separate variables and constraints for the construction of the train timetable and crew roster, respectively. These blocks are coupled by piece of work sequencing constraints and shift length constraints, which involve variables from both blocks. This unique parallel construction process is then used as the basis of a method to deal with the resolution of train disruptions in realtime. Favourable results are presented for both the combined train/driver scheduling model and the real-time disruption recovery model.

The classical world-views of discrete event simulation (DES) are event scheduling, activity scanning and process interaction. A fourth approach, the three-phase method, extends activity scanning and is often regarded as another world-view. These world-views provide the theoretical framework for applying DES in practice. However, in health care simulation, practitioners often face modeling challenges where the concepts and methodologies described by these world-views are not able to reflect either the dynamics or the entity flow of the system being modelled. This leads to individualized approaches and solutions that do not build on a unified and standardized theoretical basis. In this paper we present an extension to the activity scanning world-view based on the needs of the health care sector that uses hierarchical control structures as a more general, flexible and powerful tool to define health care DES models. To demonstrate the strength and potential of the approach two ongoing simulation studies are briefly outlined and the benefits of using the new world-view for these models is discussed. INTRODUCTION AND MOTIVATION In DES the underlying system is changed at discrete points in time. How these changes are modeled, controlled and triggered is dependent on the sub-domain of discrete event simulation, also known as the worldview, being utilized. The classical world-views are: event scheduling; activity scanning; and process interaction. However, the three phase method, which is an extension to the activity scanning approach, is also often referred to as a world-view. Much work has been done to formalize, evaluate, compare and transform the different world-views, as in (Balci 1988; Birta and Arbez 2007), or more recently (Overstreet and Nance