This paper presents an artificial neural network (ANN)-based nonlinear model predictive visual servoing method for mobile robots. The ANN model is developed for state predictions to mitigate the unknown dynamics and parameter uncertainty issues of the physics-based (PB) model. To enhance both the model generalization and accuracy for control, a two-stage ANN training process is proposed. In a pretraining stage, highly diversified data accommodating broad operating ranges is generated by a PB kinematics model and used to train an ANN model first. In the second stage, the test data collected from the actual system, which is limited in both the diversity and the volume, are employed to further finetune the ANN weights. Path-following experiments are conducted to compare the effects of various ANN models on nonlinear model predictive control and visual servoing performance. The results confirm that the pretraining stage is necessary for improving model generalization. Without pretraining (i.e., model trained only with the test data), the robot fails to follow the entire track. Weight finetuning with the captured data further improves the tracking accuracy by 0.07–0.15 cm on average.

The death of a loved one – bereavement – is a universal experience that marks the human mental health condition. Grief – the cognitive, emotional, and behavioral responses to bereavement – is thus experienced by virtually everyone at some point in life, while mourning is a process through which grievers come to terms with the loss envisioning life without the deceased. Although distress subsides over time among most bereaved individuals, a minority will develop a condition recently identified as prolonged grief disorder (PGD). The present review provides a global perspective on bereavement, grief reactions, and PGD. Although the loss of a loved one and grief reactions are in general experienced consistently across different cultures, differences and variations in their expression may exist across cultures. Especially within specific populations that may be more at risk for PGD, possibly due to risk factors associated with the mechanisms of loss (e.g., refugees, migrants, and conflict survivors). The diagnostic criteria for PGD are mostly based on Western grieving populations, and cultural adaptations of PGD treatments are limited. Therefore, cross-cultural development and validation of PGD screening/assessment is critical to support future research on grief reactions and PGD, especially in non-Western contexts, and concerning the potential future global changes and challenges that appear to have a major impact on PGD. More transcultural research on PGD is needed to contextualize and will lead to culture-bound symptom identification of PGD, and the adaptation of current treatment protocols, which may ultimately improve health at the individual level, and health-care systems.

The International Instituut Voor Sociale Geschiedenis, or International Institute of Social History, located in Amsterdam, is well known as one of the world's leading centers for research on the history of labor movements and leftist political parties. It is also a major depository of archival material. However, scholars have largely neglected the Institute's extraordinary collection of Latin American materials. The purpose of this article is to describe the two largest bodies of Latin American holdings, those pertaining to Argentina and Brazil. For reasons of space, we have kept annotations to a minimum and have included only materials published before 1940, since they constitute by far the most significant portion of the Institute's Latin American collection.

As chemical management options for weeds become increasingly limited due to selection for herbicide resistance, investigation of additional nonchemical tools becomes necessary. Harvest weed seed control (HWSC) is a methodology of weed management that targets and destroys weed seeds that are otherwise dispersed by harvesters following threshing. It is not known whether problem weeds in western Canada retain their seeds in sufficient quantities until harvest at a height suitable for collection. A study was conducted at three sites over 2 yr to determine whether retention and height criteria were met by wild oat, false cleavers, and volunteer canola. Wild oat consistently shed seeds early, but seed retention was variable, averaging 56% at the time of wheat swathing, with continued losses until direct harvest of wheat and fababean. The majority of retained seeds were >45 cm above ground level, suitable for collection. Cleavers seed retention was highly variable by site-year, but generally greater than wild oat. The majority of seed was retained >15 cm above ground level and would be considered collectable. Canola seed typically had >95% retention, with the majority of seed retained >15 cm above ground level. The suitability ranking of the species for management with HWSC was canola>cleavers>wild oat. Efficacy of HWSC systems in western Canada will depend on the target species and site- and year-specific environmental conditions.

Field trials were initiated in fall 2011 to determine the potential of pyroxasulfone to control acetolactate synthase (ALS) inhibitor-resistant weeds in field pea. Pyroxasulfone was applied in split-plot trials at five locations in western Canada using fall and PRE spring applications of 0 to 400 g ai ha−1. Trial locations were chosen with a range of soil organic matter content: 2.9, 4.3, 5.5, 10.5, and 10.6% at Scott, Kernen, Kinsella, Melfort, and Ellerslie, respectively. The herbicide dose required to reduce biomass by 50% (ED50) in false cleavers ranged between 53 and 395 g ha−1 at Scott and Ellerslie, respectively. Wild oat ED50s varied between 0.54 g ha−1 at Scott in the fall and 410 g ai ha−1 in the spring at Melfort. ED50s for wild oat and false cleavers varied by 7.4- and 746-fold, respectively, depending primarily on the organic matter content at the trial location. The effect of application timing was not consistent. Significant yield reductions and pea injury occurred at 150 and 100 g ha−1 and higher at Kernen and Scott, respectively. Low organic matter and high precipitation levels at these locations indicates increased herbicide activity under these conditions. Pyroxasulfone may allow control of ALS inhibitor-resistant false cleavers and wild oat; however, locations with high soil organic matter will require higher rates than those with low organic matter for similar control levels.

Efficient natural dispersal of herbicide-resistance alleles via seed and pollen can markedly accelerate the incidence of herbicide-resistant weed populations across an agroecoregion. Studies were conducted in western Canada in 2014 and 2015 to investigate pollen- and seed-mediated gene flow in kochia. Pollen-mediated gene flow (PMGF) from glyphosate-resistant (GR) to non-GR kochia was quantified in a field trial (hub and spoke design) at Saskatoon, Saskatchewan. Seed-mediated gene flow of acetolactate synthase (ALS) inhibitor-resistant kochia as a function of tumbleweed speed and distance was estimated in cereal stubble fields at Lethbridge, Alberta and Scott, Saskatchewan. Regression analysis indicated that outcrossing from GR to adjacent non-GR kochia ranged from 5.3 to 7.5%, declining exponentially to 0.1 to 0.4% at 96 m distance. However, PMGF was significantly influenced by prevailing wind direction during pollination (maximum of 11 to 17% outcrossing down-wind). Seed dropped by tumbleweeds varied with distance and plant speed, approaching 90% or more (ca. 100,000 seeds or more) at distances of up to 1,000 m and plant speeds of up to 300 cm s–1. This study highlights the efficient proximal (pollen) and distal (seed) gene movement of this important GR weed.

Two broad aims drive weed science research: improved management and improved understanding of weed biology and ecology. In recent years, agricultural weed research addressing these two aims has effectively split into separate subdisciplines despite repeated calls for greater integration. Although some excellent work is being done, agricultural weed research has developed a very high level of repetitiveness, a preponderance of purely descriptive studies, and has failed to clearly articulate novel hypotheses linked to established bodies of ecological and evolutionary theory. In contrast, invasive plant research attracts a diverse cadre of nonweed scientists using invasions to explore broader and more integrated biological questions grounded in theory. We propose that although studies focused on weed management remain vitally important, agricultural weed research would benefit from deeper theoretical justification, a broader vision, and increased collaboration across diverse disciplines. To initiate change in this direction, we call for more emphasis on interdisciplinary training for weed scientists, and for focused workshops and working groups to develop specific areas of research and promote interactions among weed scientists and with the wider scientific community.

In western Canada, more money is spent on wild oat herbicides than on any other weed species, and wild oat resistance to herbicides is the most widespread resistance issue. A direct-seeded field experiment was conducted from 2010 to 2014 at eight Canadian sites to determine crop life cycle, crop species, crop seeding rate, crop usage, and herbicide rate combination effects on wild oat management and canola yield. Combining 2× seeding rates of early-cut barley silage with 2× seeding rates of winter cereals and excluding wild oat herbicides for 3 of 5 yr (2011 to 2013) often led to similar wild oat density, aboveground wild oat biomass, wild oat seed density in the soil, and canola yield as a repeated canola–wheat rotation under a full wild oat herbicide rate regime. Wild oat was similarly well managed after 3 yr of perennial alfalfa without wild oat herbicides. Forgoing wild oat herbicides in only 2 of 5 yr from exclusively summer annual crop rotations resulted in higher wild oat density, biomass, and seed banks. Management systems that effectively combine diverse and optimal cultural practices against weeds, and limit herbicide use, reduce selection pressure for weed resistance to herbicides and prolong the utility of threatened herbicide tools.

Developments in assisted human reproduction (AHR) have aroused considerable debate and interest around the world, with most governments accepting that they are matters of public policy. This politicization of AHR is explored in the context of a consideration of the oft-used term “the best interests of the child.” This “rallying call” is frequently cited as the primary concern in the determination of policy. This article is based on the contention that it is important to examine the interplay between the three main groups directly influencing “best interest” outcomes for AHR offspring. These groups are the professionals, the parents, and the state. It seeks to examine how this high-sounding and well-meaning commitment is addressed, advanced, or ignored in the interplay of these groups.

The purpose of this paper is to advance an approach to analyzing decision-making by front line public officials. The notion of discretion in front line decision-making has been examined widely in the law and society literature. However, it has often failed to capture the different kinds and levels of decisions that enforcement officials make. Taking an interdisciplinary approach that draws on political, sociological, and legal analysis, we propose a new conceptual framework, one that draws a sharper distinction between discretion and judgment and teases out distinct levels in the scope and depth of decision-making. We then use this framework to create a conceptual map of the decision-making process of front-line officials charged with enforcing the Employment Standards Act (ESA) of Ontario, demonstrating that a deeper, more precise analysis of discretion and judgment can contribute to a richer understanding of front line decision-making and its social, political, and legal implications.