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Potato is the third most important staple food crop globally following rice and wheat. In the United States, potato is grown on approximately 410,000 ha with a farm-gate value of US$1,032 million. In Canada, potato is grown on approximately 134,000 ha with a farm-gate value of US$235 million. The objective of this manuscript, compiled by the Weed Science Society of America Weed Loss Committee, was to estimate potato yield loss caused by weed interference. Potato yield data from weedy and weed-free plots (or plots with >95% weed control) was obtained from researchers working on weed management in potato in the United States and Canada or from published manuscripts from 2000 to 2018. Potato yield loss from weed interference was 12% to 61% when no weed management tactics were implemented. The average yield loss for all states/provinces (where data was obtained) due to weed interference was 44%. Weed interference would cause a farm-gate loss of approximately US$465 million and US$61 in the United States and Canada, respectively, if weeds are not controlled. These results indicate that weed management is critical for successful potato production, and that an ongoing need for research exists on weed management in this crop.
The intersection of paleontology and biomechanics can be reciprocally illuminating, helping to improve paleobiological knowledge of extinct species and furthering our understanding of the generality of biomechanical principles derived from study of extant species. However, working with data gleaned primarily from the fossil record has its challenges. Building on decades of prior research, we outline and critically discuss a complete workflow for biomechanical analysis of extinct species, using locomotor biomechanics in the Triassic theropod dinosaur Coelophysis as a case study. We progress from the digital capture of fossil bone morphology to creating rigged skeletal models, to reconstructing musculature and soft tissue volumes, to the development of computational musculoskeletal models, and finally to the execution of biomechanical simulations. Using a three-dimensional musculoskeletal model comprising 33 muscles, a static inverse simulation of the mid-stance of running shows that Coelophysis probably used more upright (extended) hindlimb postures and was likely capable of withstanding a vertical ground reaction force of magnitude more than 2.5 times body weight. We identify muscle force-generating capacity as a key source of uncertainty in the simulations, highlighting the need for more refined methods of estimating intrinsic muscle parameters such as fiber length. Our approach emphasizes the explicit application of quantitative techniques and physics-based principles, which helps maximize results robustness and reproducibility. Although we focus on one specific taxon and question, many of the techniques and philosophies explored here have much generality to them, so they can be applied in biomechanical investigation of other extinct organisms.
Throughout their 250 Myr history, archosaurian reptiles have exhibited a wide array of body sizes, shapes, and locomotor habits, especially in regard to terrestriality. These features make Archosauria a useful clade with which to study the interplay between body size, shape, and locomotor behavior, and how this interplay may have influenced locomotor evolution. Here, digital volumetric models of 80 taxa are used to explore how mass properties and body proportions relate to each other and locomotor posture in archosaurs. One-way, nonparametric, multivariate analysis of variance, based on the results of principal components analysis, shows that bipedal and quadrupedal archosaurs are largely distinguished from each other on the basis of just four anatomical parameters (p < 0.001): mass, center of mass position, and relative forelimb and hindlimb lengths. This facilitates the development of a quantitative predictive framework that can help assess gross locomotor posture in understudied or controversial taxa, such as the crocodile-line Batrachotomus (predicted quadruped) and Postosuchus (predicted biped). Compared with quadrupedal archosaurs, bipedal species tend to have relatively longer hindlimbs and a more caudally positioned whole-body center of mass, and collectively exhibit greater variance in forelimb lengths. These patterns are interpreted to reflect differing biomechanical constraints acting on the archosaurian Bauplan in bipedal versus quadrupedal groups, which may have shaped the evolutionary histories of their respective members.
Medical experts may be instructed by designated bodies such as the coroner or the court, to provide expert witness statements concerning patients treated under their care. Such reports are factual and are prepared on the basis of the medical records and personal recollection of events. Other authorities such as the Driving Vehicle and Licensing Agency can also seek information on patients with traumatic brain injury. In the civil court, experts may advise on matters relating to personal injury and medical negligence. Reports are usually based upon review of records, and often medical examination of the claimant. The expert may be instructed to provide reports on condition, prognosis and/or causation. This chapter discusses liaison with the various authorities that require medico-legal input relevant to head injury and whiplash.
The major determinant of outcome from TBI is the severity of the primary injury; however, not all brain damage happens at that time point. Invariably, primary injury activates cellular and molecular cascades which mediate potentially reversible, secondary injury in the ensuing hours and days. These events can lead to progressive brain swelling and increased intracranial pressure (ICP) thus compromising cerebral perfusion pressure (CPP) and cerebral blood flow (CBF) resulting in tissue ischaemia, hypoxia and cellular energy failure. Further cell damage exacerbates the brain swelling, forming part of a vicious circle that can lead to life-threatening brain herniation. A large body of evidence links post-traumatic intracranial hypertension at levels above 20 to 25 mmHg with excess mortality and worse functional outcomes.
Intracranial pressure (ICP) is well recognised as a critical parameter to both measure and influence in the management of the head injured patient. Since Lundberg’s seminal studies, ICP has arguably become the major focus of monitoring in head injury, as well as a number of other neurosurgical scenarios.1 Mean ICP and the features that make up the ICP waveform provide insight into the state of elastance and compliance of the injured brain, impending trends and events related to changes in intracranial pathophysiology, and also end-prognosis in traumatic brain injury (TBI).
Advocating a pragmatic and multidisciplinary approach to the management of patients with brain injuries, Traumatic Brain Injury provides a detailed description of care along the whole-patient pathway. Delivering an evidence-based update on the optimal care of both adult and paediatric patients who have sustained injuries ranging from mild to severe, information from on-going multi-centre studies in neurotrauma is included. The basic scientific principles of neuropathology, head injury research and scoring systems are presented before detailed sections on emergency department care, patient transfer, intensive care and longer-term care. Rehabilitation is reviewed in detail with chapters discussing the aims and roles of physiotherapy, occupational therapy and neuropsychology amongst others. Discussing medico-legal issues in detail, the effect of injury on the individual and their family are also examined. Emphasising a holistic approach to caring for patients with brain injuries, this is an essential guide for all involved.
We report an experimental study of photocarrier lifetime, transport, and excitation spectra in silicon-on-insulator doped with sulfur far above thermodynamic saturation. The spectral dependence of photocurrent in coplanar structures is consistent with photocarrier generation throughout the hyperdoped and undoped sub-layers, limited by collection of holes transported along the undoped layer. Holes photoexcited in the hyperdoped layer are able to diffuse to the undoped layer, implying (μτ)h ∼ 5 × 10−9 cm2/V. Although high absorptance of hyperdoped silicon is observed from 1200 to 2000 nm in transmission experiments, the number of collected electrons per absorbed photon is 10−4 of the above-bandgap response of the device, consistent with (μτ)e < 1 × 10−7cm2/V.