The Impact of Age and Physical Activity Level on Manual Aiming Performance

Older adults traditionally adapt their discrete aiming movements, thereby travelling a larger proportion of the movement under closed-loop control. As the beneficial impact of a physically active lifestyle in old age has been described for several aspects of motor control, we compared the aiming performance of young controls to active and sedentary older adults. To additionally determine the contribution of visual feedback, aiming movements were executed with and without saccades. Results showed only sedentary older adults adopted the typical movement changes, highlighting the impact of a physically active lifestyle on manual aiming in old age. In an attempt to reveal the mechanism underlying the movement changes, evidence for an age-related decline in force control was found, which in turn resulted in an adapted aiming strategy. Finally, prohibiting saccades did not affect older adults’ performance to a greater extent, suggesting they do not rely more on visual feedback than young controls. Keywords: aging, physical activity, manual aiming, eye movement

Parental perspectives long term after neonatal clinical trial participation: a survey

Background: Although recruiting newborns is ethically challenging, clinical trials remain essential to improve neonatal care. There is a lack of empirical data on the parental perspectives following participation of their neonate in a clinical trial, especially at long term. The objective of this study is to assess experiences and emotions of parents, long term after trial participation in an interventional drug trial. Methods: Parents of former participants of five neonatal interventional drug trials were surveyed at long term (3– 13 years ago) after participation. The survey assessed parental contentment with trial participation, perceived influence of the trial on care and health, emotional consequences of participation, and awareness of typical clinical trial characteristics on 6-point Likert scales. Results: Complete responses were received from 123 parents (52% of involved families). Twenty percent of parents did not remember participation. Those who remembered participation reported high contentment with overall trial participation (median 5.00), but not with follow-up (median 3.00). Most parents did not perceive any influence of the trial on care (median 2.00) and health (median 2.43). Almost all parents reported satis

Fashioning Entitlements: A Comparative Law and Economic Analysis of the Judicial Role in Environmental Centralization in the U.S. and Europe

This paper identifies and evaluates, from an economic point of view, the role of the judiciary the steady shift of environmental regulatory authority to higher, more centralized levels of government in both the U.S. and Europe. We supply both a positive analysis of how the decisions made by judges have affected the incentives of both private and public actors to pollute the natural environment, and normative answers to the question of whether judges have acted so as to create incentives that move levels of pollution in an efficient direction, toward their optimal, cost-minimizing (or net-benefit-maximizing) levels. Highlights of the analysis include the following points: 1) Industrial-era local (state or national) legislation awarding entitlements to pollute was almost certainly inefficient due to a fundamental economic obstacle faced by those who suffer harm from the over-pollution of publicly owned natural resources: the inability to monetize and credibly commit to repay the future economic value of reducing pollution. 2) When industrial era pollution spilled across state lines in the US, the federal courts, in particular the Supreme Court, fashioned a federal common law of interstate nuisance that set up essentially the same sort of blurry, uncertain entitlements to pollute or be free of pollution that had been created by the state courts in resolving local pollution disputes. We argue that for the typical pollution problem, a legal regime of blurry interstate entitlements - with neither jurisdiction having a clear right either to pollute or be free of pollution from the other - is likely to generate efficient incentives for interjursidictional bargaining, even despite the public choice problems besetting majority-rule government. Interestingly, a very similar system of de facto entitlements arose and often stimulated interjursidictional bargaining in Europe as well as in the U.S. 3) The US federal courts have generally interpreted the federal environmental statutes in ways that give clear primacy to federal regulators. Through such judicial interpretation, state and local regulators face a continuing risk of having their decisions overridden by federal regulators. This reduces the incentives for regulatory innovation at the state and local level. Judicial authorization of federal overrides has thus weakened the economic rationale for cooperative federalism suggested by economic models of principal-agent relationships. As a result of the principle of attribution, there is less risk in Europe that (like in the US) courts would enlarge the federal purview and thereby limit the powers of the Member States. Despite this principle, the power of the European bureaucracy (that is, the European Commission) has steadily increased and led to a steady shift of environmental regulatory competencies to the European level. This shift is only sometimes normatively desirable, and yet there is little that the ECJ can or will do to slow it

Spatial distribution of rock fragments in cultivated soils in northern Ethiopia as affected by lateral and vertical displacement processes

Although, in semi-arid environments, rock fragments at the soil surface and within the topsoil play an important role in desertification control, little is known about their spatial distribution. Therefore, this study analyses spatial patterns of rock fragment cover along catenas, and the vertical variations in volumetric rock fragment content in soil profiles in the highlands of Tigray, northern Ethiopia. Natural and anthropogenic processes inducing these patterns are assessed. Volumetric rock fragment content (R-V) was analysed in 10 soil pits. All rock fragments were extracted, and their volumes determined by pedo-stratigraphic unit, size and lithology. The rock fragment cover (R-C) was determined by the point-count method using vertical photographs of the soil surface. The following processes contribute to the vertical variability of R-V: (1) in Vertisols, upsqueezing as a consequence of swell-shrink cycles (argillipedoturbation) is responsible for high R-C at the soil surface; (2) large rock fragments (> 7.5 cm) are rapidly brought to the soil surface by kinetic sieving through tillage, even in the case of continuous fine sediment deposition, what may result in a rock fragment rich subsoil, underlying a thick soil layer (up to 80 cm) without large rock fragments and a topsoil with a high R-C at the surface; (3) Skeletic Regosols at the foot of cliffs show no systematic vertical rock fragment distributions. As to rock fragment cover along the catena, some fundamental differences appear between the basalt and limestone substrate. On the basalt catena with slope gradients between 0.06 and 0.42 m m(-1), R-C is high everywhere (57-85%) and is unrelated to slope gradient. Vertical processes such as kinetic sieving through ploughing and argillipedoturbation determine the rock fragment distribution at the soil surface. In limestone areas, argillipedoturbation is less active and R-C is positively correlated with slope gradient (R-2 = 0.74; n = 6; P 2 cm) and more kinetic sieving sensitive rock fragments lowers R-2 to 0.46 (n = 6; n.s.). Preconditions for the present spatial distribution of rock fragments at the soil surface in the study area are the occurrence of two geomorphic processes in the past: (1) mudflows depositing diamictons including much coarse debris and (2) intense water erosion, which occurred after deforestation and exposed rock fragments at or near to the soil surface. Generally, the balance between lateral and vertical movements of rock fragments now, controls the spatial distribution of R-C. With respect to the lateral displacement processes: (1) lateral transport over the soil surface by trampling, tillage and concentrated runoff, especially on steep slopes, and (2) rockfall from the cliffs. Vertical supply of rock fragments to the soil surface is caused by (1) selective runoff erosion and the development of erosion pavements, (2) tillage induced kinetic sieving, bringing preferentially large rock fragments (>7.5 cm) to the soil surface, and (3) argillipedoturbation in Vertisol areas. (C) 2002 Elsevier Science B.V. All rights reserved.status: publishe