Impact of Biogenic Carbon Neutrality Assumption for Achieving a Net-Zero Emission Target: Insights from a Techno-Economic Analysis.

Global pathways limiting warming to 2 °C or below require deep carbon dioxide removal through a large-scale transformation of the land surface, an increase in forest cover, and the deployment of negative emission technologies (NETs). Government initiatives endorse bioenergy as an alternative, carbon-neutral energy source for fossil fuels. However, this carbon neutral assumption is increasingly being questioned, with several studies indicating that it may result in accounting errors and biased decision-making. To address this growing issue, we use a carbon budget model combined with an energy system model. We show that including forest sequestration in the energy system model alleviates the decarbonization effort. We discuss how a forest management strategy with a high sequestration capacity reduces the need for expensive negative emission technologies. This study indicates the necessity of establishing the most promising forest management strategy before investing in bioenergy with carbon capture and storage. Finally, we describe how a carbon neutrality assumption may lead to biased decision-making because it allows the model to use more biomass without being constrained by biogenic CO2 emissions. The risk of biased decision-making is higher for regions that have lower forest coverage, since available forest sequestration cannot sink biogenic emissions in the short term, and importing bioenergy could worsen the situation.

Prospective life cycle assessment of viticulture under climate change scenarios, application on two case studies in France.

Viticulture needs to satisfy consumers' demands for environmentally sound grape and wine production while envisaging adaptation options to diminish the impacts of projected climate change on future productivity. However, the impact of climate change and the adoption of adaptation levers on the environmental impacts of future viticulture have not been assessed. This study evaluates the environmental performance of grape production in two French vineyards, one located in the Loire Valley and another in Languedoc-Roussillon, under two climate change scenarios. First, the effect of climate-induced yield change on the environmental impacts of future viticulture was assessed based on grape yield and climate data sets. Second, besides the climate-induced yield change, this study accounted for the impacts of extreme weather events on grape yield and the implementation of adaptation levers based on the future probability and potential yield loss due to extreme events. The life cycle assessment (LCA) results associated with climate-induced yield change led to opposite conclusions for the two vineyards of the case study. While the carbon footprint of the vineyard from Languedoc-Roussillon is projected to increase by 29 % by the end of the century under the high emissions scenario (SSP5-8.5), the corresponding footprint is projected to decrease in the vineyard from the Loire Valley by approximately 10 %. However, when including the effect of extreme events and adaptation options, the life cycle environmental impacts of grape production are projected to drastically increase for both vineyards. For instance, under the SSP5-8.5 scenario, the carbon footprint for the vineyard of Languedoc-Roussillon is projected to increase fourfold compared to the current footprint, while it will rise threefold for the vineyard from the Loire Valley. The obtained LCA results emphasized the need to account for the impact of both climate change and extreme events on grape production under future climate change scenarios.

Three-dimensional kinematic evaluation of lateral suture stabilization in an in vitro canine cranial cruciate deficient stifle model.

The impact of surgical correction of cranial cruciate ligament rupture (CCLR) on 3D kinematics has not been thoroughly evaluated in dogs. The success of current techniques remains limited, as illustrated by suboptimal weightbearing and progression of osteoarthritis. The inability to restore the stifle's 3D kinematics might be a key element in understanding these suboptimal outcomes. The objective of this study was to evaluate the impact of lateral suture stabilization (LSS) on the 3D kinematics of the canine stifle joint. We hypothesized that LSS would not restore 3D kinematics in our model. Ten cadaveric pelvic limbs collected from large dogs (25-40 kg) were tested using a previously validated apparatus that simulates gait. Three experimental conditions were compared: (a) intact stifle; (b) unstable stifle following cranial cruciate ligament transection (CCLt) and (c) CCLt stabilized by LSS. Three-dimensional kinematics were collected through 5 loading cycles simulating the stance phase of gait and curves were analyzed using a Wilcoxon signed-rank test. LSS restored baseline kinematics for the entire stance phase for cranial and lateromedial translation, flexion, and abduction. It restored distraction over 90% of the stance phase. Internal rotation was limited, but not restored. This in vitro study had limitations, as it used a simplified model of stifle motion and weight-bearing. The results of this study report that LSS can restore physiologic 3D kinematics largely comparable to those of healthy stifles. Suboptimal outcome in patients following CCLR stabilization by LSS may therefore result from causes other than immediate postoperative abnormal 3D kinematics.

Are early clinical manifestations of spasticity associated with long-term functional outcome following spinal cord injury? A retrospective study.

STUDY DESIGN: Retrospective study of a prospective cohort of patients with traumatic spinal cord injury (SCI). OBJECTIVES: Determine the relationship between the occurrence of early spasticity, defined as the development of signs and/or symptoms of spasticity during the hospitalization in traumatology, and the functional outcome 6-12 months following a SCI. Secondly, to determine the specific impact of early clonus, velocity-dependent hypertonia and/or muscle spasms on the functional outcome at the same timepoint. SETTING: Single trauma center specialized in SCI care. METHODS: One hundred sixty-two patients sustaining an acute traumatic SCI were included in the analyses. Comparative analysis was performed to describe the characteristics of patients with early spasticity. Correlations were performed to determine the relationship between the clinical signs of spasticity and the Spinal Cord Independence Measure (SCIM) scores collected 6-12 months after SCI. RESULTS: 51.9% of the cohort developed clinical signs of spasticity during the hospitalization in traumatology (29.7 days) following SCI. These showed a significantly lower total SCIM score and subscores compared to individuals without early spasticity at follow-up (p < 0.05). After adjusting for confounding factors, the occurrence of early spasms was only clinical sign of spasticity significantly associated with a decreased mobility at follow-up (r = -0.17, p = 0.04). CONCLUSIONS: The development of signs and symptoms of spasticity, in particular the occurrence of spasms in the first month following the injury may be associated with decreased functional outcome and mobility. Early assessment of spasticity following SCI is thus recommended.

Temporally-differentiated biogenic carbon accounting of wood building product life cycles.

Although standards have identified temporary carbon storage as an important element to consider in wood product LCAs, there has been no consensus on a methodology for its accounting. This work aims to improve the accounting of carbon storage and fluxes in long-life wood products in LCA. Biogenic carbon from harvested roundwood logs were tracked using the Carbon Budget Model Framework for Harvested Wood Products (CBMF-HWP). Carbon flows through wood product manufacturing, building life and end-of-life phases, and carbon stocks and fluxes from harvest to the atmosphere were estimated. To cover the products commonly used in the Canadian building industry, a range of softwood products types, provinces and territories and building lifetimes were considered. In addition, policy scenarios were considered in order to model the effects of dynamic parameters through time as a policy target is reached. Most wood products have similar emissions profiles, though cross-laminated timber has higher sawmill emissions and oriented-strand board has higher initial post-demolition emissions. The region of construction is also predictive of the initial post-demolition emissions. Higher recycling rates shift materials from landfills into subsequent product systems, thus avoiding landfill emissions. Landfill decay rates are affected by climate and results in a large range of landfill emissions. The degree of postponement of end-of-life emissions is highly dependent upon the wood product type, region and building lifespan parameters. This work develops biogenic carbon profiles that allows for modelling dynamic cradle-to-grave LCAs of Canadian wood products. SUPPLEMENTARY INFORMATION: The online version of this article (doi:10.1007/s42452-020-03979-2) contains supplementary material, which is available to authorized users.

Addressing temporal considerations in life cycle assessment.

In life cycle assessment (LCA), temporal considerations are usually lost during the life cycle inventory calculation, resulting in an aggregated "snapshot" of potential impacts. Disregarding such temporal considerations has previously been underlined as an important source of uncertainty, but a growing number of approaches have been developed to tackle this issue. Nevertheless, their adoption by LCA practitioners is still uncommon, which raises concerns about the representativeness of current LCA results. Furthermore, a lack of consistency can be observed in the used terms for discussions on temporal considerations. The purpose of this review is thus to search for common ground and to identify the current implementation challenges while also proposing development pathways. This paper introduces a glossary of the most frequently used terms related to temporal considerations in LCA to build a common understanding of key concepts and to facilitate discussions. A review is also performed on current solutions for temporal considerations in different LCA phases (goal and scope definition, life cycle inventory analysis and life cycle impact assessment), analysing each temporal consideration for its relevant conceptual developments in LCA and its level of operationalisation. We then present a potential stepwise approach and development pathways to address the current challenges of implementation for dynamic LCA (DLCA). Three key focal areas for integrating temporal considerations within the LCA framework are discussed: i) define the temporal scope over which temporal distributions of emissions are occurring, ii) use calendar-specific information to model systems and associated impacts, and iii) select the appropriate level of temporal resolution to describe the variations of flows and characterisation factors. Addressing more temporal considerations within a DLCA framework is expected to reduce uncertainties and increase the representativeness of results, but possible trade-offs between additional data collection efforts and the increased value of results from DLCAs should be kept in mind.

Three-dimensional kinematic evaluation of Tightrope CCL in a canine in vitro cranial cruciate deficient stifle model.

The impact of surgical correction of cranial cruciate ligament-deficient stifles (CCDS) on the 3-dimensional (3D) kinematics of the canine stifle has been sparsely evaluated. Tightrope (TR) cranial cruciate ligament (CCL) has been proposed to restore baseline 3D kinematics in CCDS by using isometric points. We hypothesized that TR would restore baseline 3D kinematics of the stifle in our model. Ten pelvic limbs were used with a previously validated apparatus. Three experimental conditions were evaluated: i) intact stifle, ii) cranial cruciate ligament transection (CCLt), and iii) CCLt stabilized with TR; kinematic data was recorded. Tightrope CCL in CCDS did not limit sagittal flexion. Tightrope CCL neutralized internal rotation without restoring baseline curves, but it did not restore abduction, nor did it neutralize or restore cranial translation, but it did restore latero-medial and proximo-distal translations. In our model, TR without pre-conditioning of the FiberTape strands did not restore baseline stifle 3D kinematics and residual cranial translation could result in frequent meniscal tears.

L'impact de la correction chirurgicale d'une déficience du ligament croisé crânial du genou (CCDS) sur la cinématique du grasset canin a été peu étudié. La technique de restauration du ligament croisé crânial (CCL) appelée 'Tightrope' (TR) a été proposée pour restaurer la cinématique 3D lors de CCDS en utilisant des points isométriques. Nous avons émis l'hypothèse que la technique TR restaurerait la cinématique 3D d'origine du grasset dans notre modèle. Dix membres pelviens ont été utilisés avec un appareil préalablement validé. Trois conditions expérimentales furent évaluées : i) grasset intact, ii) transsection du ligament croisé crânial (CCLt), et iii) CCLt stabilisé par TR; et les données de cinématique furent enregistrées. La technique TR lors de CCL n'a pas limité la flexion sagittale. Cette technique neutralisait la rotation interne sans restaurer les courbes d'origine, mais elle ne restaurait pas l'abduction, ni ne neutralisait ou restaurait une translation crâniale, mais elle a restauré les translations latéro-médiale et proximo-distale. Dans notre modèle, la technique TR sans préconditionnement des bandes FiberTape n'a pas restauré la cinématique 3D d'origine et une translation crâniale résiduelle pourrait résulter en des déchirures fréquentes du ménisque.(Traduit par Docteur Serge Messier).

Assessment of Regional Bone Density in Fractured Vertebrae Using Quantitative Computed Tomography.

STUDY DESIGN: Cohort study. PURPOSE: The aim of this study is to propose and evaluate a new technique to assess bone mineral density of fractured vertebrae using quantitative computed tomography (QCT). OVERVIEW OF LITERATURE: There is no available technique to estimate bone mineral density (BMD) at the fractured vertebra because of the alterations in bony structures at the fracture site. METHODS: Forty patients with isolated fracture from T10 to L2 were analyzed from the vertebrae above and below the fracture level. Apparent density (AD) was measured based on the relationship between QCT images attenuation coefficients and the density of calibration objects. AD of 8 independent regions of interest (ROI) within the vertebral body and 2 ROI within the pedicles of vertebrae above and below the fractured vertebra were measured. At the level of the fractured vertebra, AD was measured at the pedicles, which are typically intact. AD of the fractured vertebral body was linearly interpolated, based on the assumption that AD at the fractured vertebra is equivalent to the average AD measured in vertebrae adjacent to the fracture. Estimated and measured AD of the pedicles at the fractured level were compared to verify our assumption of linear interpolation from adjacent vertebrae. RESULTS: The difference between the measured and the interpolated density of the pedicles at the fractured vertebra was 0.006 and 0.003 g/cm3 for right and left pedicle respectively. The highest mean AD located at the pedicles and the lowest mean AD was found at the anterior ROI of the vertebral body. Significant negative correlation exist between age and AD of ROI in the vertebral body. CONCLUSIONS: This study suggests that the proposed technique is adequate to estimate the AD of a fractured vertebra from the density of adjacent vertebrae.

Experimental Model of Proximal Junctional Fracture after Multilevel Posterior Spinal Instrumentation.

There is a high risk of proximal junctional fractures (PJF) with multilevel spinal instrumentation, especially in the osteoporotic spine. This problem is associated with significant morbidity and possibly the need for reoperation. Various techniques have been proposed in an attempt to decrease the risk of PJF but there is no experimental model described for in vitro production of PJF after multilevel instrumentation. The objective of this study is to develop an experimental model of PJF after multilevel posterior instrumentation. Initially, four porcine specimens including 4 vertebrae and instrumented at the 3 caudal vertebrae using a pedicle screw construct were subjected to different loading conditions. Loading conditions on porcine specimens involving cyclic loading along the axis of the center vertebral body line, with constrained flexion between 0° and 15° proximally, and fully constraining the specimen distally resulted in a fracture pattern most representative of a PJF seen clinically in humans, so to undergo human cadaveric testing with similar loading conditions was decided. Clinically relevant PJF were produced in all 3 human specimens. The experimental model described in this study will allow the evaluation of different parameters influencing the incidence and prevention of PJF after multilevel posterior spinal instrumentation.

The influence of proximal anchors on the risk of proximal junctional fracture in the osteoporotic spine: biomechanical comparison between pedicle screws and transverse process hooks.

STUDY DESIGN: Biomechanical comparison of the risk of proximal junctional fracture (PJF) after multilevel spinal instrumentation using pedicle screws or transverse process hooks on the top of a pedicle screw construct. OBJECTIVE: To compare the loads leading to PJF when using pedicle screws or transverse process hooks at the proximal level after multilevel spinal instrumentation using pedicle screws. SUMMARY OF BACKGROUND DATA: With stronger spinal fixation techniques, there is increased risk of PJF, especially in the osteoporotic spine. The use of transverse process hooks over pedicle screws at the proximal level of multilevel pedicle screw constructs has been proposed to decrease the incidence of PJF. However, there is no biomechanical study evaluating this concept. METHODS: Twenty-four segments of 4 vertebrae from 6 human cadaveric spines were evaluated after instrumentation of the distal 3 vertebrae using pedicle screws, except at the top of the construct where either pedicle screws (AP group) or transverse process hooks (PTPH group) were placed. The proximal vertebra was left uninstrumented. Quantitative computed tomography scan was used before instrumentation in order to assess the bone density for each specimen. Cyclic compression loading between 50 and 1000 N at 1 Hz was applied to each of 24 instrumented spinal segments until obtaining a PJF. RESULTS: Bone density was similar between the AP and PTPH groups. A PJF occurred in 22 of 24 tested specimens. The number of cycles required to produce the PJF ranged between 2 and 1002. The number of cycles required to produce the PJF was similar between the AP construct group (median: 3; interquartile range: 3-7) and the PTPH construct group (median: 4; interquartile range: 3-5). CONCLUSIONS: The current study failed to observe a significant impact of using transverse process hooks over pedicle screws on top of multilevel pedicle screw construct to decrease the risk of PJF.

Axial load-bearing capacity of an osteochondral autograft stabilized with a resorbable osteoconductive bone cement compared with a press-fit graft in a bovine model.

BACKGROUND: Osteochondral autografts in mosaicplasty are inserted in a press-fit fashion, and hence, patients are kept nonweightbearing for up to 2 months after surgery to allow bone healing and prevent complications. Very little has been published regarding alternative fixation techniques of those grafts. HYPOTHESIS: Osteochondral autografts stabilized with a resorbable osteoconductive bone cement would have a greater load-bearing capacity than standard press-fit grafts. STUDY DESIGN: Controlled laboratory study. METHODS: Biomechanical testing was conducted on 8 pairs of cadaveric bovine distal femurs. For the first 4 pairs, 6 single osteochondral autografts were inserted in a press-fit fashion on one femur. On the contralateral femur, 6 grafts were stabilized with a calcium triglyceride osteoconductive bone cement. For the 4 remaining pairs of femurs, 4 groups of 3 adjacent press-fit grafts were inserted on one femur, whereas on the contralateral femur, grafts were cemented. After a maturation period of 48 hours, axial loading was applied on all single grafts and on the middle graft of each 3-in-a-row series. RESULTS: For the single-graft configuration, median loads required to sink the press-fit and cemented grafts by 2 and 3 mm were 281.87 N versus 345.56 N (P = .015) and 336.29 N versus 454.08 N (P = .018), respectively. For the 3-in-a-row configuration, median loads required to sink the press-fit and cemented grafts by 2 and 3 mm were 260.31 N versus 353.47 N (P = .035) and 384.83 N versus 455.68 N (P = .029), respectively. CONCLUSION: Fixation of osteochondral grafts using bone cement appears to improve immediate stability over the original mosaicplasty technique for both single- and multiple-graft configurations. CLINICAL RELEVANCE: Achieving greater primary stability of osteochondral grafts could potentially accelerate postoperative recovery, allowing early weightbearing and physical therapy.

Passive contribution of the rotator cuff to abduction and joint stability.

PURPOSE: The purpose of this study is to compare shoulder joint biomechanics during abduction with and without intact non-functioning rotator cuff tissue. METHODS: A cadaver model was devised to simulate the clinical findings seen in patients with a massive cuff tear. Eight full upper limb shoulder specimens were studied. Initially, the rotator cuff tendons were left intact, representing a non-functional rotator cuff, as seen in suprascapular nerve paralysis or in cuff repair with a patch. Subsequently, a massive rotator cuff tear was re-created. Three-dimensional kinematics and force requirements for shoulder abduction were analyzed for each condition using ten abduction cycles in the plane of the scapula. RESULTS: Mediolateral displacements of the glenohumeral rotation center (GHRC) during abduction with an intact non-functioning cuff were minimal, but massive cuff tear resulted in significant lateral displacement of the GHRC (p < 0.013). Similarly, massive cuff tear caused increased superior migration of the GHRC during abduction compared with intact non-functional cuff (p < 0.01). From 5 to 30° of abduction, force requirements were significantly less with an intact non-functioning cuff than with massive cuff tear (p < 0.009). CONCLUSION: During abduction, an intact but non-functioning rotator cuff resulted in decreased GHRC displacement in two axes as well as lowered the force requirement for abduction from 5 to 30° as compared with the results following a massive rotator cuff tear. This provides insight into the potential biomechanical effect of repairing massive rotator cuff tears with a biological or synthetic "patch," which is a new treatment for massive cuff tear.

Considering time in LCA: dynamic LCA and its application to global warming impact assessments.

The lack of temporal information is an important limitation of life cycle assessment (LCA). A dynamic LCA approach is proposed to improve the accuracy of LCA by addressing the inconsistency of temporal assessment. This approach consists of first computing a dynamic life cycle inventory (LCI), considering the temporal profile of emissions. Then, time-dependent characterization factors are calculated to assess the dynamic LCI in real-time impact scores for any given time horizon. Although generally applicable to any impact category, this approach is developed here for global warming, based on the radiative forcing concept. This case study demonstrates that the use of global warming potentials for a given time horizon to characterize greenhouse gas emissions leads to an inconsistency between the time frame chosen for the analysis and the time period covered by the LCA results. Dynamic LCA is applied to the US EPA LCA on renewable fuels, which compares the life cycle greenhouse gas emissions of different biofuels with fossil fuels including land-use change emissions. The comparison of the results obtained with both traditional and dynamic LCA approaches shows that the difference can be important enough to change the conclusions on whether or not a biofuel meets some given global warming reduction targets.

A low-cost thermoelectrically cooled tissue clamp for in vitro cyclic loading and load-to-failure testing of muscles and tendons.

In vitro cyclic loading and load-to-failure testing of muscles and tendons require a reliable linking device between tissues and the actuator that can transmit high loads without slippage or tissue damage. This article describes a simple custom-made thermoelectrically cooled freeze clamp. The effectiveness of the clamp to transmit loads without tissue slippage was evaluated on 10 canine quadriceps femoris myo-tendinous junctions in both load-to-failure and cyclic loading settings. Dynamic cyclic loading during an extensive period of time was successfully achieved. Loads up to 4.84 kN were applied in quasi-static conditions without evidence of clamp slippage or failure.

The effect of axis alignment on shoulder joint kinematics analysis during arm abduction.

BACKGROUND: A joint coordinate system allows coherence between the performed movement, its mathematical representation and the clinical interpretation of the kinematics of joint motion. In 2005, the International Society of Biomechanics (ISB) defined a joint coordinate system for the shoulder. To improve kinematics interpretation, the ISB suggested aligning the coordinate systems of the humerus and the scapula. Therefore, the aim of this research project was to determine how the alignment of the joint coordinate system axes can influence the interpretation of shoulder joint kinematics. More precisely, we wanted to investigate if mathematical alignment of the reference and moving coordinate system axes could facilitate the kinematic interpretation of a simple abduction movement without introducing additional coupled motion. METHODS: An experiment was carried out on eight shoulder cadaveric specimens. Elevation of the arm in the scapular plane (abduction) was recorded using an electromagnetic tracking device. Three-dimensional angular displacements of the arm during elevation in the scapular plane were described using the standard ISB joint coordinate system, and using a modified joint coordinate system for which the axes were mathematically aligned. FINDINGS: The results obtained revealed a difference in the interpretation of the starting angles between the ISB joint coordinate system and the aligned coordinate system. No difference was found in the interpretation of the angular range of motion (P<0.01). INTERPRETATION: The aligned coordinate system provided a standardized starting angle of elevation that allows an easier clinical interpretation of shoulder kinematics.