Applying theory of constraints to timber harvesting: A case study from the Northeast USA

Logging firms are a critical link in wood supply chains, connecting forest landowners with markets for wood products. Improving operational planning can benefit individual logging firms as well as the larger wood supply chain in which they operate. Applying concepts from Theory of Constraints (TOC) to timber harvesting may help achieve greater predictability and efficiency when planning harvest operations. However, examples that demonstrate how TOC can improve logging operations are lacking. This study focuses on the analysis of production and activity data collected during the harvest of a temperate mixed hardwood forest in the Northeast United States using a chainsaw-forwarder system through a TOC lens. Specifically, the drum-buffer-rope (DBR) method was used to reschedule operator and machine activities such that a consistent flow of wood from stump to landing was maintained despite anticipated production setbacks. The results of this case study provide insights into the usefulness of applying TOC to logging operations. In particular, logging businesses must be able to estimate machine and operator productivity within a given harvest context to identify and exploit system constraints, while taking full advantage of unused capacity of any non-constraint functions

Applying Theory of Constraints to Timber Harvesting: A Case Study from the Northeast USA

Logging firms are a critical link in wood supply chains, connecting forest landowners with markets for wood products. Improving operational planning can benefit individual logging firms as well as the larger wood supply chain in which they operate. Applying concepts from Theory of Constraints (TOC) to timber harvesting may help achieve greater predictability and efficiency when planning harvest operations. However, examples that demonstrate how TOC can improve logging operations are lacking. This study focuses on the analysis of production and activity data collected during the harvest of a temperate mixed hardwood forest in the Northeast United States using a chainsaw-forwarder system through a TOC lens. Specifically, the drum-buffer-rope (DBR) method was used to reschedule operator and machine activities such that a consistent flow of wood from stump to landing was maintained despite anticipated production setbacks. The results of this case study provide insights into the usefulness of applying TOC to logging operations. In particular, logging businesses must be able to estimate machine and operator productivity within a given harvest context to identify and exploit system constraints, while taking full advantage of unused capacity of any non-constraint functions

Attributes and definitions of locomotor capacity in older people: a World Health Organisation (WHO) locomotor capacity working group meeting report

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Quantifying the Life Cycle Greenhouse Gas Emissions of a Mechanized Shelterwood Harvest Producing Both Sawtimber and Woodchips

Forests are used to mitigate anthropogenic greenhouse gas (GHG) emissions through carbon offset programs, and forest management is generally accepted as “carbon neutral”. However, forest harvesting operations depend heavily on fossil fuels, so it would be remiss to broadly paint all forms of management as carbon neutral without empirical verification of this claim. Biomass feedstock, as a means to supplant fossil fuel consumption, has received the bulk of investigative efforts, as the carbon benefit of biomass is one of the most contentious among wood products, because it does not create long-term carbon storage. A life cycle assessment (LCA) was conducted on a winter shelterwood harvest occurring in the Adirondacks of upstate New York. Primary data were collected daily throughout the operation and used to model the impact attributed to producing clean chips and logs for delivery to a pulp mill and sawmill, respectively. This harvest produced 4894 Mg of clean chips and 527 Mg of sawtimber. We calculated that 39.77 and 25.16 kg of carbon dioxide equivalent were emitted per Mg of clean chips and sawtimber, respectively, with a total observed flow of GHG into the atmosphere between 206 and 210 thousand kilograms. The results contribute to our understanding of the global warming potential of implementing a forest harvest to produce raw materials for medium- and long-term carbon storage products such as paper and dimensional hardwood lumber

Quantifying the Life Cycle Greenhouse Gas Emissions of a Mechanized Shelterwood Harvest Producing Both Sawtimber and Woodchips

Forests are used to mitigate anthropogenic greenhouse gas (GHG) emissions through carbon offset programs, and forest management is generally accepted as “carbon neutral”. However, forest harvesting operations depend heavily on fossil fuels, so it would be remiss to broadly paint all forms of management as carbon neutral without empirical verification of this claim. Biomass feedstock, as a means to supplant fossil fuel consumption, has received the bulk of investigative efforts, as the carbon benefit of biomass is one of the most contentious among wood products, because it does not create long-term carbon storage. A life cycle assessment (LCA) was conducted on a winter shelterwood harvest occurring in the Adirondacks of upstate New York. Primary data were collected daily throughout the operation and used to model the impact attributed to producing clean chips and logs for delivery to a pulp mill and sawmill, respectively. This harvest produced 4894 Mg of clean chips and 527 Mg of sawtimber. We calculated that 39.77 and 25.16 kg of carbon dioxide equivalent were emitted per Mg of clean chips and sawtimber, respectively, with a total observed flow of GHG into the atmosphere between 206 and 210 thousand kilograms. The results contribute to our understanding of the global warming potential of implementing a forest harvest to produce raw materials for medium- and long-term carbon storage products such as paper and dimensional hardwood lumber

Impacts of forestry best management practices on logging costs and productivity in the northeastern USA

Best management practices (BMPs) effectively mitigate erosion and sedimentation during and immediately after harvest operations. The responsibility for implementing BMPs typically falls on loggers, with implications for higher harvesting costs and, possibly, reduced logging productivity. Two methods were used to assess the impacts of BMPs on logging operations in the northeastern United States. First, a case study was conducted using shift-level production and activity data and machine rate calculations to assess the impacts of BMP implementation for eight harvest operations, ranging from single-operator hand-felling systems to fully mechanized whole-tree and cut-to-length systems. Second, a survey was conducted in which loggers were asked to estimate the number of days required to complete a hypothetical timber harvest with and without a set of prescribed BMPs and to indicate their minimum acceptable contract rates for each. The combined results revealed a range of costs from $0/ac to$62/ac and decreases in productivity between 0 and 20%

Applying the “Goldilocks Rule” to Riparian Buffer Widths for Forested Headwater Streams across the Contiguous U.S.—How Much Is “Just Right”?

Delineating riparian management zones (RMZ) around streams to protect riparian ecological functions is critical during forest management. This study compared the area dedicated to RMZ using the USFS functional-based riparian buffer approach versus individual state-defined riparian buffer allocation strategies along headwater streams across 17 states within the US. The USFS method uses a variable-width riparian buffer that seeks to capture the functions of a riparian area. Our study sought to contrast this USFS method with various state-defined RMZ guidelines. The functional approach delineated the highest percentages of the watershed area around headwater streams in most watersheds, sometimes >20% of forestland, whereas state RMZ guidelines delineated <10% of forestland around headwater streams in many watersheds. Although many state guidelines failed to identify the variable widths of functional riparian areas, some watersheds in the Great Lakes states over-allocated forestland as riparian when compared to a functional riparian delineation. The topographic and forest composition differences observed across the study area were not represented by their respective state RMZ guidelines, and these variables strongly influence the delineation of a functional RMZ

True believers: the recption of Descartes's meditations by Malebranche and Huet

Both Nicholas Malebranche and Pierre-Daniel Huet were at first positively influenced by Descartes's Meditations, and both came to perceive shortcomings in that work. With respect to mind-body dualism, Malebranche attempted to strengthen Descartes's position by jettisoning clarity and distinctness basing it instead on a principle of intentionality. Huet jettisoned the whole position in favor of skepticism. The source of their different responses lay in their different estimations of Descartes's integrity.<br>Tanto Nicholas Malebranche como Pierre-Daniel Huet foram inicialmente positivamente influenciados pelas Meditações de Descartes e ambos terminaram por perceber falhas nesta obra. No que concerne o dualismo mente e corpo, Malebranche buscou fortalecer a posição cartesiana abandonando o critério de clareza e distinção em favor de um princípio de intencionalidade. Huet abandonou o cartesianismo como um todo em favor do ceticismo. A fonte destas respostas diversas está nas avaliações distintas que fizeram da integridade de Descartes

Surgical site infection after gastrointestinal surgery in children : an international, multicentre, prospective cohort study

Introduction Surgical site infection (SSI) is one of the most common healthcare-associated infections (HAIs). However, there is a lack of data available about SSI in children worldwide, especially from low-income and middle-income countries. This study aimed to estimate the incidence of SSI in children and associations between SSI and morbidity across human development settings. Methods A multicentre, international, prospective, validated cohort study of children aged under 16 years undergoing clean-contaminated, contaminated or dirty gastrointestinal surgery. Any hospital in the world providing paediatric surgery was eligible to contribute data between January and July 2016. The primary outcome was the incidence of SSI by 30 days. Relationships between explanatory variables and SSI were examined using multilevel logistic regression. Countries were stratified into high development, middle development and low development groups using the United Nations Human Development Index (HDI). Results Of 1159 children across 181 hospitals in 51 countries, 523 (45 center dot 1%) children were from high HDI, 397 (34 center dot 2%) from middle HDI and 239 (20 center dot 6%) from low HDI countries. The 30-day SSI rate was 6.3% (33/523) in high HDI, 12 center dot 8% (51/397) in middle HDI and 24 center dot 7% (59/239) in low HDI countries. SSI was associated with higher incidence of 30-day mortality, intervention, organ-space infection and other HAIs, with the highest rates seen in low HDI countries. Median length of stay in patients who had an SSI was longer (7.0 days), compared with 3.0 days in patients who did not have an SSI. Use of laparoscopy was associated with significantly lower SSI rates, even after accounting for HDI. Conclusion The odds of SSI in children is nearly four times greater in low HDI compared with high HDI countries. Policies to reduce SSI should be prioritised as part of the wider global agenda.Peer reviewe