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A model of vertical differentiation in which foreign high value and domestic low value consumers incur congestion costs in using a common resource is discussed. The provision of multiple environmental goods demonstrate that providing differential qualities, may be best even if domestic consumers do not use the high quality resources at all.

The design of patient specific weight-bearing exercises after the surgical implementation of internal fixations is of critical importance for bone fracture healing. The purpose of this study is to theoretically investigate the effects of physiologically relevant dynamic loading on early stage of fracture healing under different locking compression plate (LCP) configurations. The finite element results show that dynamic loading enhanced transport of bone cells and growth factors in the fracture callus is much dependent on the flexibility of LCP. In comparison to free diffusion, a relatively flexible LCP together with dynamic loading could significantly enhance solute transport in callus. For example, a flexible LCP achieved by increasing WL (Working Length) and BPD (Bone Plate Distance) (e.g. WL=100 mm and BPD=2 mm) together with a 5-h 150 N@1 Hz dynamic loading could increase the uptake of chondrocytes by around 280% compared to free diffusion, osteoblasts by around 180%, osteogenic growth factors by around 120% and chondrogenic growth factors by around 220%. In addition, dynamic loading enhanced transport of cells and growth factors under LCP is spatially dependent with a relatively higher enhancement in far cortex zone than that in near cortex zone. The outcomes from present study could potentially assist orthopaedic surgeons to determine optimal loading regimes with consideration of patient specific LCP configurations. • Enhanced cell transport under dynamic loading depends on fixation flexibility. • Far cortical zone exhibit higher enhancement of cell uptake than near cortical zone. • Chondrocyte enhancement is higher in relatively smaller gap size of 1 mm. • Higher loading magnitude produce better mesenchymal stem cells enhancement. [ABSTRACT FROM AUTHOR]

Background Rotator cuff tears following anatomic total shoulder arthroplasty increase with duration of follow-up. This study aimed to evaluate contact pressure between the rotator cuff tendons and prosthesis after anatomic total shoulder arthroplasty and compare these with the tendon-contact pressures in the native shoulder. Methods Eight entire upper extremities were mounted onto a testing apparatus, and simulated muscle loading was applied to each rotator cuff tendon with the shoulder positioned in abduction, internal rotation, and external rotation. Pressure-sensitive film placed between each tendon and bone was used to measure the resultant tendon contact pressures. Experiments were repeated after anatomic total shoulder arthroplasty using standardized implant sizes, and pressure-sensitive film was used to evaluate tendon-prosthesis contact pressure. Results Both joint angle and shoulder joint replacement surgery had significant effects on the maximum contact pressure measured between the humeral head and all rotator cuff tendons (P <.05) except the teres minor. The supraspinatus demonstrated a significantly larger peak tendon contact pressure after surgery at 45° of abduction relative to that in the native shoulder (mean difference, 0.2 MPa; P =.031), while the subscapularis had a significantly larger maximum contact pressure at 10° of abduction (mean difference, 0.45 MPa; P =.032) and 90° of abduction (mean difference, 0.80 MPa; P =.008) postoperatively. Conclusion Anatomic total shoulder arthroplasty results in significantly larger tendon contact pressures relative to those in the native shoulder. High tendon contact pressures may ultimately predispose rotator cuff tendons to postoperative wear-induced damage and tearing. [ABSTRACT FROM AUTHOR]

Designing weight-bearing exercises for patients with lower-limb bone fractures is challenging and requires a systematic approach that accounts for patient-specific loading conditions. However, 'trial-and-error' approaches are commonplace in clinical settings due to the lack of a fundamental understanding of the effect of weight-bearing exercises on the bone healing process. Whilst computational modelling has the potential to assist clinicians in designing effective patient-specific weight-bearing exercises, current models do not explicitly account for the effects of muscle loading, which could play an important role in mediating the mechanical microenvironment of a fracture site. We combined a fracture healing model involving a tibial fracture stabilised with a locking compression plate (LCP) with a detailed musculoskeletal model of the lower limb to determine interfragmentary strains in the vicinity of the fracture site during both full weight-bearing (100% body weight) and partial weight-bearing (50% body weight) standing. We found that muscle loading significantly altered model predictions of interfragmentary strains. For a fractured bone with a standard LCP configuration (bone-plate distance = 2 mm, working length = 30 mm) subject to full weight-bearing, the predicted strains at the near and far cortices were 23% and 11% higher when muscle loading was included compared to the case when muscle loading was omitted. The knee and ankle muscles accounted for 38% of the contact force exerted at the knee joint during quiet standing and contributed significantly to the strains calculated at the fracture site. Thus, models of bone fracture healing ought to account explicitly for the effects of muscle loading. Furthermore, the study indicated that LCP configuration parameters play a crucial role in influencing the fracture site microenvironment. The results highlighted the dominance of working length over bone-plate distance in controlling the flexibility of fracture sites stabilised with LCP devices. [Display omitted] • The importance of muscle loading on fracture healing analyses in highlighted. • Muscle loads could be up to 38% of the joint loads for quiet standing. • Omitting muscle loads may lead up to 25% error in interfragmentary strain predictions. [ABSTRACT FROM AUTHOR]

Obesity has been identified as an independent risk factor for a wide range of health conditions. Therefore, there is a clear need for high quality Bariatric research in order to improve patient selection, outcomes and safety for patients with obesity. We sought to identify and compare the quantitative and qualitative publication output from Bariatric centres in England. We identified 42 National Health Service (NHS) Trusts and 162 surgeons providing Bariatric services in England. A median of 4 (range 1–7) Bariatric surgeons were identified per centre. Eight NHS Trusts (19%) and 75 surgeons (46.3%) had no Bariatric publications during the study period, while 87 surgeons published a total of 432 Bariatric papers. Only 15 surgeons (9%) had ≥10 publications within the study period. However, these surgeons produced >50% of all Bariatric publications. Departments with more than 4 surgeons produced a significantly higher number of Bariatric publications (median 8.5 vs 2, p = 0.01). There is significant variation in research contribution amongst Bariatric centres in England. Academia should be encouraged and promoted across all bariatric services in order to broaden our understanding on Bariatric outcomes by expanding the service and proportional increase in funding. Given that a number of health conditions can afflict individuals living with obesity, bariatric surgery research becomes all the more important. [ABSTRACT FROM AUTHOR]

Background: Rotator cuff repair surgery aims to create a secure, pressurized tendon-bone footprint to permit re-establishment of the fibrovascular interface and tendon healing. Flat-braided suture-tape is an alternative suture material to traditional suture-wire that has potential to reproduce a larger repair construct contact area. The objective of this study was to compare contact pressure, area as well as the mechanical fatigue strength between suture-wire and suture-tape Suture-bridge repair constructs in an ovine model.Methods: Sixty lamb infraspinatus tendons were harvested and randomly allocated to three- and four-anchor Suture-bridge repairs performed using either suture-wire or suture-tape. Thirty-two specimens were cyclically loaded for 200 cycles in an Instron testing machine, while tendon gap formation was recorded using a high speed digital motion analysis system. Loading to failure was then performed to evaluate construct ultimate tensile strength and stiffness. The remaining 28 specimens were assessed for repair contact pressure and area using pressure-sensitive film.Results: There was a significantly greater average tendon contact pressure (mean difference: 0.064 MPa, p = 0.04) and area (mean difference: 2.71 mm2, p = 0.03) in fiber-tape repair constructs compared to those in fiber-wire constructs for the three-anchor Suture-bridge configuration. The four-anchor suture-tape constructs had a significantly larger ultimate tensile strength than that of the four-anchor suture-wire constructs (mean difference: 56.4 N, p = 0.04). There were no significant differences in gap formation or stiffness between suture-tape and suture-wire constructs (p > 0.05).Conclusion: Suture-tape offers greater pressurised tendon-bone contact than suture-wire in three-anchor Suture-bridge repairs, while greater mechanical strength is achieved with the use of suture-tape in four-anchor Suture-bridge constructs. [ABSTRACT FROM AUTHOR]

A great deal of evidence suggests that partial weight-bearing exercise plays an important role in bone fracture healing. However, current physiotherapy program tends to follow the “Let's try it and see” strategy due to the lack of a fundamental understanding of in vivo mechanical environment required for the better healing outcomes. The purpose of present study is to develop an innovative framework to predict the healing outcomes as a result of post-surgical physical therapy. The raw acceleration data corresponding to a series of walking tests is firstly captured by ActiGraph accelerometers, and then used as input to theoretically estimate the peak ground reaction force (PGRF) and peak loading rate (PLR). Finally, the healing outcomes as a result of different walking speeds are predicated based on the interfragmentary movement (IFM) measured by using mechanical testing. The results show that PGRF and PLR are important factors for the callus tissue differentiation at the early stage of healing. The developed model could potentially allow the design of effective patient specific post-surgical physical therapy. [ABSTRACT FROM AUTHOR]

Mechano-regulation plays a crucial role in bone healing and involves complex cellular events. In this study, we investigate the change of mechanical microenvironment of stem cells within early fracture callus as a result of the change of fracture obliquity, gap size and fixation configuration using mechanical testing in conjunction with computational modelling. The research outcomes show that angle of obliquity ( θ ) has significant effects on interfragmentary movement (IFM) which influences mechanical microenvironment of the callus cells. Axial IFM at near cortex of fracture decreases with θ , while shear IFM significantly increases with θ . While a large θ can increase shear IFM by four-fold compared to transverse fracture, it also result in the tension–stress effect at near cortex of fracture callus. In addition, mechanical stimuli for cell differentiation within the callus are found to be strongly negatively correlated to angle of obliquity and gap size. It is also shown that a relatively flexible fixation could enhance callus formation in presence of a large gap but could lead to excessive callus strain and interstitial fluid flow when a small transverse fracture gap is present. In conclusion, there appears to be an optimal fixation configuration for a given angle of obliquity and gap size. [ABSTRACT FROM AUTHOR]

Femtosecond laser-written integrated devices involving Fresnel Zone Plates (FZPs) and waveguide arrays are demonstrated as built-in optical couplers. These structures were fabricated in borosilicate glass using a direct laser writing technique. The optical properties of these integrated photonic structures were investigated using CW lasers and high-resolution CCDs. For a single FZP coupled to a single waveguide, the overall coupling efficiency was 9%. A multiplexed optical coupler composed of three FZP layers was demonstrated to couple three waveguides simultaneously in a waveguide array. Structures of this type can be used as platforms for multichannel waveguide coupling elements or as microfluidic sensors that require higher light collecting efficiency. [ABSTRACT FROM AUTHOR]

Introduction Knowledge about the functional consequences of lower limb long bone fractures is helpful to inform patients, clinicians and employers about their recovery process and prognosis. This study aims to describe the epidemiology and health outcomes of femoral and tibial shaft fractures treated at two level I trauma centres, by comparing the differences between patients with delayed union or nonunion and patients with union. Patients and methods An analysis of registry data over two years, supplemented with medical record review, was conducted. Fracture healing was retrospectively assessed by clinical and radiological evidence of union, and the need for surgical intervention. SF-12 scores, and work and pain status were prospectively recorded at six and twelve months post injury. Results 285 fractures progressed to union and 138 fractures developed delayed union or nonunion. There was a significant difference between the two cohorts with regards to the mechanism of injury, association with multi-trauma, open fractures, grade of Gustilo classification, patient fund source, smoking status and presence of comorbidities. The SF-12 physical component score was less than 50 at both six and twelve months with improvement in the union group, but not in the delayed union or nonunion group. 72% of patients with union had returned to work at one year, but 54% continued to have pain. The difference compared to patients with delayed union or nonunion was significant. Discussion Even patients whose fractures unite in the expectant time-frame will have residual physical disability. Patients with delayed union or nonunion have still poorer outcomes, including ongoing problems with returning to work and pain. It is important to educate patients about their injury so that they have realistic expectations. This is particularly relevant given that the patients most likely to sustain femoral or tibial shaft fractures are working-age healthy adults, and up to a third of fractures may develop delayed union or nonunion. Conclusion Despite modern treatment, the patient-reported outcomes of lower limb long bone shaft fractures do not return to normal at one year. Patients with delayed union or nonunion can expect poorer outcomes. [ABSTRACT FROM AUTHOR]

Background Context: While burst fracture is a well-known cause of spinal canal occlusion with dynamic, axial spinal compression, it is unclear how such loading mechanisms might cause occlusion without fracture.Purpose: To determine how spinal canal occlusion during dynamic compression of the lumbar spine is differentially caused by fracture or mechanisms without fracture and to examine the influence of spinal level on occlusion.Study Design: A cadaveric biomechanical study.Methods: Twenty sets of three-vertebrae specimens from all spinal levels between T12 and S1 were subjected to dynamic compression using a hydraulic loading apparatus up to a peak velocity between 0.1 and 0.9 m/s. The presence of canal occlusion was measured optically with a high-speed camera. This was repeated with incremental increases of 4% compressive strain until a vertebral fracture was detected using acoustic emission measurements and computed tomographic imaging.Results: For axial compression without fracture, the peak occlusion (Omax) was 29.9±10.0%, which was deduced to be the result of posterior bulging of the intervertebral disc into the spinal canal. Omax correlated significantly with lumbar spinal level (p<.001), the compressive displacement (p<.001) and the cross-sectional area of the vertebra (p=.031).Conclusions: Spinal canal occlusion observed without vertebral fracture involves intervertebral disc bulging. The lower lumbar spine tended to be more severely occluded than more proximal levels.Clinical Significance: Clinically, intermittent canal occlusion from disc bulging during dynamic compression may not show any radiographic features. The lower lumbar spine should be a focus of injury prevention intervention in cases of high-rate axial compression. [ABSTRACT FROM AUTHOR]

The paper reports measurements of the vacuum-ultraviolet spectral irradiances of a flat zinc target over a wavelength region of 124–164 nm generated by 10 and 60 ns duration low-intensities, 5 × 10 9 - 3 × 10 10  W cm −2 , 1.06 μm wavelength laser pulses. Maximum radiation conversion efficiencies of 2.5%/2 π sr and 0.8%/2 π sr were measured for 60 and 10 ns laser pulses at the intensities of 5 × 10 9 and 1.4 × 10 10  W cm −2 , respectively. Atomic structure calculations using a relativistic configuration-interaction, flexible atomic code and a developed non-local thermodynamic equilibrium population kinetics model in comparison to the experimental spectra detected by the Seya-Namioka type monochromator reveal the strong broadband experimental emission originates mainly from 3d 9 4p-3d 9 4s, 3d 9 4d-3d 9 4p and 3d 8 4p-3d 8 4s, 3d 8 4d-3d 8 4p unresolved-transition arrays of double and triple ionized zinc, respectively. Two-dimensional radiation-hydrodynamics code is used to investigate time-space plasma evolution and spectral radiation of a 10 ns full-width-at-half-maximum Gaussian laser pulse-zinc interaction. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to review the complication rate and profile associated with surgical fixation of acute midshaft clavicle fracture in a large cohort of patients treated in a level I trauma centre.Patients and Methods: We identified all patients who underwent surgical treatment of acute midshaft clavicle fracture between 2002 and 2010. The study group consisted of 138 fractures (134 patients) and included 107 men (78%) and 31 women (22%); the median age of 35 years (interquartile range (IQR) 24-45). The most common mechanism of injury was a road traffic accident (78%). Sixty percent (n=83) had an injury severity score of ≥15 indicating major trauma. The most common fracture type (75%) was simple or wedge comminuted (2B1) according to the Edinburgh classification. The median interval between the injury and operation was 3 days (IQR 1-6). Plate fixation was performed in 110 fractures (80%) and intramedullary fixation was performed in 28 fractures (20%). There were 85 men and 25 women in the plate fixation group with median age of 35 years (IQR 25-45) There were 22 men and six women in the intramedullary fixation group with median age of 31 years (IQR 24-42 years). Statistical analysis was performed using independent sample t test, Mann Whitney test, and Chi square test. Significant P-value was <0.05.Results: The overall incidence of complication was 14.5% (n=20). The overall nonunion rate was 6%. Postoperative wound infection occurred in 3.6% of cases. The incidence of complication associated with plate fixation was 10% (11 of 110 cases) compared to 32% associated with intramedullary fixation (nine of 28 cases; P=0.003). Thirty-five percent of complications were related to inadequate surgical technique and were potentially avoidable. Symptomatic hardware requiring removal occurred in 23% (n=31) of patients. Symptomatic metalware was more frequent after plate fixation compared to intramedullary fixation (26% vs 7%, P=0.03).Conclusions: Intramedullary fixation of midshaft clavicle fracture is associated with a higher incidence of complications. Plate fixation is associated with a higher rate of symptomatic metalware requiring removal compared to intramedullary fixation. Approximately one in three complications may be avoided by attention to adequate surgical technique. [ABSTRACT FROM AUTHOR]

• A narrow linewidth, tunable 80 W thulium fiber laser is presented. • Low doping concentration thulium fiber was used to avoid thermal degradation. • System performance was optimized to investigate thermal blooming. • Effects of thermal blooming on laser propagation have been investigated. We describe the design and characterization of a tunable narrow linewidth thulium-doped fiber laser source which combines a core-pumped preamplifier and high power cladding-pumped amplifier, providing >80 W average power. The single-frequency wavelength output from 1.92 um to 2.01 µm is digitally tunable to target specific atmospheric absorption and transmission windows for applications targeting atmospheric transmission at 2 µm. Results from preliminary thermal blooming studies are presented. [ABSTRACT FROM AUTHOR]

Abstract: Absorber-free transmission and butt-welding of different polymers were performed using thulium fiber laser radiation at the wavelength 2μm. The relations between the laser process conditions and the dimensions and quality of the seam were investigated by means of optical and phase-contrast microscopy. Mechanical properties of the weld joints were studied in tensile strength tests. Laser-welded polyethylene samples revealed a tensile strength of greater than 80% of the bulk material strength. Transmission welding of different polymer combinations featured the formation of different joint classes depending on the spectral properties. The experiments demonstrate new application areas of mid-IR fiber laser sources for materials processing. [Copyright &y& Elsevier]

Abstract: Study design: Prospective cohort study. Objective: To identify factors that predict poor patient-reported outcomes in patients with traumatic vertebral body fracture(s) of the thoracic and/or lumbar spine without neurological deficit. Summary of background data: There is a paucity of information on factors that predict poor patient-reported outcomes in patients with traumatic vertebral body fracture(s) of the thoracic and/or lumbar spine without neurological deficit. Methods: Patients were identified from the Victorian Orthopaedic Trauma Outcomes Registry (VOTOR). VOTOR includes all patients with orthopaedic trauma admitted to the two adult Level 1 trauma centres in Victoria, Australia. Patient-reported outcomes and data on possible predictive factors, including demographic details, injury-related and treatment-based factors, were obtained from the VOTOR database. Patient-reported outcomes were measured at 12 months post-injury using the 12-Item Short-Form Health Survey (SF-12), a Numerical Rating Scale (NRS) for pain, global outcome questions and data was collected on return to work or study. For the identification of predictive factors, univariate analyses of outcome vs. each predictor were carried out first, followed by logistic multiple regression. Results: 344 patients were eligible for the study and data were obtained for 264 (76.7%) patients at 12 months follow-up. Patients reported ongoing pain at 12 months post-injury (moderate–severe: 33.5%), disability (70.1%) and inability to return to work or study (23.3%). A number of demographic, injury-related and treatment-based factors were identified as being predictive of poor patient-reported outcomes. Patients who had associated radius fracture(s) were more likely to have moderate to severe disability (odds ratio (OR)=3.85, 95% confidence interval=1.30–11.39), a poorer physical health status (OR=3.73, 1.37–10.12) and moderate to severe pain (OR=3.23, 1.22–8.56) at 12 months post-injury than patients without radius fracture. Patients who did not receive compensation for work-related or road traffic-related injuries were less likely to report moderate to severe pain (OR=0.45, 0.23–0.90) or have a poorer mental health status (OR=0.17, 0.04–0.70) at 12 months post-injury than those who received compensation. Conclusions: The prognostic factors identified in this study may assist clinicians in the identification of patients requiring more intensive follow-up or additional rehabilitation to ultimately improve patient care. [Copyright &y& Elsevier]

Abstract: Double-Pulse Laser-Induced Breakdown Spectroscopy of iron using both Nd:YAG and TEA–CO2 lasers has been investigated to better understand mechanisms of signal enhancement. The signal dependence on the delay between the two laser pulses shows an enhanced signal when the CO2 laser pulse interacts with the sample before the Nd:YAG pulse. Signal kinetics and a simple model of sample heating by the CO2 pulse show that the enhancement during the first 700ns is due primarily to sample heating. Images of the sample surface after ablation as well as time-integrated pictures of the plasma suggest that particles are ejected from the surface during the first microseconds after the arrival of the CO2 pulse and provide fuel for the subsequent plasma created by the Nd:YAG laser. [Copyright &y& Elsevier]

• A photothermal process was employed to tune Ge-As-Pb-Se films' refractive indices. • The index change was studied as a function of laser and heat treatment conditions. • The index change is repeatable and scalable for films with thicknesses up to 40 µm. • The study provides crucial guidance towards a gradient refractive index structure. The development of infrared gradient refractive index (GRIN) components relies on the ability to modify the refractive index and dispersion properties of suitable host materials with a high spatial selectivity and a sufficient magnitude of change. We present a novel multi-step approach to induce local refractive index changes in chalcogenide optical materials. Films with thicknesses between 1 and 40 µm fabricated from multi-component GeSe 2 -As 2 Se 3 -PbSe (GAP–Se) glass-ceramic materials were irradiated with continuous-wave and nanosecond-pulsed laser light, and post-processed with heat-treatments. A maximum local refractive index change of Δ n = 0.088 across a broad spectral range in the infrared was realized. Spatial control of the refractive index variation was achieved through thermally-induced crystallization of a Pb-rich crystal phase. The magnitude of the index change scaled with the laser power and the exposure dose while the material maintained the required optical quality. The material performance validated in this study for thick films (20–40 µm films) reconfirms our ability to extend results from thin GAP-Se films towards novel optical designs. [ABSTRACT FROM AUTHOR]

• Of the 6186 vulnerable road users studied over the 8-year period, 43% were motorcyclists, 32% and 25% were pedestrians. • Problems with usual activities at 6 months, and pain/discomfort at 12 months, were most prevalent. • The adjusted odds of reporting problems on all EQ-5D-3 L items were lower for cyclists when compared to pedestrians. • An average cyclist had a greater odds of a good recovery and returning to work after injury, compared to an average pedestrian. Pedestrians, cyclists and motorcyclists are vulnerable to serious injury due to limited external protective devices. Understanding the level of recovery, and differences between these road user groups, is an important step towards improved understanding of the burden of road trauma, and prioritisation of prevention efforts. This study aimed to characterise and describe patient-reported outcomes of vulnerable road users at 6 and 12 months following orthopaedic trauma. A registry-based cohort study was conducted using data from the Victorian Orthopaedic Trauma Outcomes Registry (VOTOR) and included pedestrians, cyclists and motorcyclists who were hospitalised for an orthopaedic injury following an on-road collision that occurred between January 2009 and December 2016. Outcomes were measured using the 3-level EuroQol 5 dimensions questionnaire (EQ-5D-3 L), Glasgow Outcome Scale – Extended (GOS-E) and return to work questions. Outcomes were collected at 6 and 12 months post-injury. Multivariable generalized estimating equations (GEE), adjusted for confounders, were used to compare outcomes between the road user groups over time. 6186 orthopaedic trauma patients met the inclusion criteria during the 8-year period. Most patients were motorcyclists (42.8%) followed by cyclists (32.6%) and pedestrians (24.6%). Problems were most prevalent on the usual activities item of the EQ-5D-3 L at 6-months post-injury, and the pain/discomfort item of the EQ-5D-3 L at 12 months. The adjusted odds of reporting problems on all EQ-5D-3 L items were lower for cyclists when compared to pedestrians. Moreover, an average cyclist had a greater odds of a good recovery on the GOS-E, (AOR 2.75, 95% CI 2.33, 3.25) and a greater odds of returning to work (AOR = 3.13, 95% CI 2.46, 3.99) compared to an average pedestrian. Pedestrians and motorcyclists involved in on-road collisions experienced poorer patient-reported outcomes at 6 and 12 months post-injury when compared to cyclists. A focus on both primary injury prevention strategies, and investment in ongoing support and treatment to maximise recovery, is necessary to reduce the burden of road trauma for vulnerable road users. [ABSTRACT FROM AUTHOR]