Marginal integration for nonparametric causal inference

We consider the problem of inferring the total causal effect of a single variable intervention on a (response) variable of interest. We propose a certain marginal integration regression technique for a very general class of potentially nonlinear structural equation models (SEMs) with known structure, or at least known superset of adjustment variables: we call the procedure S-mint regression. We easily derive that it achieves the convergence rate as for nonparametric regression: for example, single variable intervention effects can be estimated with convergence rate $n^{-2/5}$ assuming smoothness with twice differentiable functions. Our result can also be seen as a major robustness property with respect to model misspecification which goes much beyond the notion of double robustness. Furthermore, when the structure of the SEM is not known, we can estimate (the equivalence class of) the directed acyclic graph corresponding to the SEM, and then proceed by using S-mint based on these estimates. We empirically compare the S-mint regression method with more classical approaches and argue that the former is indeed more robust, more reliable and substantially simpler.Comment: 40 pages, 14 figure

A spatial impedance controller for robotic manipulation

Mechanical impedance is the dynamic generalization of stiffness, and determines interactive behavior by definition. Although the argument for explicitly controlling impedance is strong, impedance control has had only a modest impact on robotic manipulator control practice. This is due in part to the fact that it is difficult to select suitable impedances given tasks. A spatial impedance controller is presented that simplifies impedance selection. Impedance is characterized using ¿spatially affine¿ families of compliance and damping, which are characterized by nonspatial and spatial parameters. Nonspatial parameters are selected independently of configuration of the object with which the robot must interact. Spatial parameters depend on object configurations, but transform in an intuitive, well-defined way. Control laws corresponding to these compliance and damping families are derived assuming a commonly used robot model. While the compliance control law was implemented in simulation and on a real robot, this paper emphasizes the underlying theor

The science of law and modern public administration

Założeniem badawczym artykułu jest poddanie opisowi zasadniczych problemów bytu i funkcjonowania administracji publicznej we współczesności, problematyki nauki administracji oraz prawa administracyjnego. Opis i argumentacja dotyczą szerokiego spektrum zagadnień związanych z przeglądem wybranych współczesnych dziedzin funkcjonowania administracji, a zarazem także z ewolucją struktur i układów administracyjnych. Zastosowanie znajduje tu pewna ilość nowych terminów wstępnie wypracowanych. Cechą współczesnych procesów prawnych i politycznych jest konwergencja o charakterze globalnym. Stanowi ona wynik szeroko pojmowanego problemu globalizacji, czyli umiędzynarodowiania wszelkich dziedzin życia społecznego. Konwergencja globalna w prawie prowadzi często do nowych standardów, deregulacji, nowych uregulowań. Swoistym zagadnieniem badawczym jest tu prawo ponadnarodowe. Pozostaje ono w szczególnie dynamicznej łączności z prawem publicznym, a także z administracją publiczną.Problematyka dotyczy także aktualnego stanu nauki prawa i koniecznego rozwoju jej poznania, teorii. W szerszym zagadnieniu dotyczy rozwoju doktryn społecznych i ich uosabiania zwłaszcza w życiu politycznym i w życiu prawnym. Dostrzegalne i ważne w tych sferach są zagadnienia relacji podmiotowości i władztwa. Procesy współczesnego życia społecznego, a także przykłady szczególne dają podstawę złożonym problemom. Administracja musi aktualnie zmierzać do struktur ewoluujących wraz ze społeczeństwem, musi być strukturą chłonną i uczącą się, dającą podstawę bytowi działań innowacyjnych. Innowacje i inwencje są zasadniczym celem i potrzebą działania administracyjnego i funkcjonowania układów administracyjnych. Stanowią zasadniczy trzon postępu, i jedno z najistotniejszych współczesnych zagadnień prawnych.Ciągle istotna jest centralizacja. Administracja staje tu przed coraz szerszą skalą zadań. Multiplikuje się nie tylko wymiar potrzeb, ale zarazem szerokie zagadnienie regulacji prawnej. Powracają problemy regulacji i wykładni zagadnień prawnych, interesu publicznego, partii politycznych, praw podmiotowych, podmiotowości wobec władztwa, podziału władzy oraz zasad państwa prawnego. Przejawiają się one komparatystycznie w wielu kulturach prawnych, mimo nierzadko zmiennej frazeologii i różnego stanu zaawansowania w rozstrzyganiu problemów prawnych. Rozwiązań trzeba tu poszukiwać nie tylko w zmiennych wartościach doktrynalnych czy systemowych, ale też w tych szczególnych zmiennych wartościach, które dotyczą organizacji, kontroli, nadzoru, policji administracyjnej, a zatem tych pojęć i urządzeń, które są podstawowe dla nauki administracji i nauki prawa administracyjnego.The aim of this research paper is deliberation on the essential problems of existence and functioning of public administration in modern times as well as on some issues of the science administration and administrative law. The description and argumentation cover a wide spectrum of issues relating to the review of contemporary areas of administrative activity as well as to the evolution of administrative structures and systems. A number of new terms, preliminarily developed, is therefore used. One of the features of contemporary legal and political processes is convergence of a global nature, which is a result of broadly understood globalisation, namely the internationalisation of all aspects of social life. Global convergence frequently leads to new standards, deregulation and new regulations. A particular research issue is supranational law, dynamically linked to public law and public administration.The paper looks into the current condition of the science of law and calls for further cognitive studies. These include development of social doctrines and their personification in political and legal life, in particular. Here, the relationships between subjectivity and power are of significant importance. The processes of contemporary social life give rise to complex problems andadministration must evolve together with society. It must be able to adapt to new circumstances and create foundations for innovative activities. Innovation and invention are the fundamental goal of administrative actions and functioning of administrative structures. They constitute the principal pillar of progress and development and belong to the most important legal issues of the contemporary world.Centralisation continues to be essential as well. Administration faces an increasing range of tasks. The scale of needs multiplies, which then calls for new regulations and produces new legal issues. Regulation, interpretation of law, public interest, separation of powers, the rule of law, subjectivity and subjective rights are recurring issues and are comparatively manifested in many legal cultures, despite frequently varying phraseology and different levels of advancement in solving new legal problems. Solutions must be sought not only in doctrinal or system variables, but also in the specific variables relating to the organisation, control, supervision, or administrative police, and thus in these concepts and institutions that are fundamental for the science of administration and administrative law.

Compressive Strength Testing of Toughskin Thin Spray-On Liner

Thin spray-on liners (TSLs) have been attracting more and more attention as an alternative to the steel mesh in underground roadway support. In order to investigate and compare the compressive strength of glass fibre reinforced ToughSkin TSL developed at the University of Wollongong, a compression test was developed using the cube samples of 40 mm in size. The effect of a small amount of glass fibre in the polymer matrix was tested. The test results indicate that the compressive strength and the material stiffness of the cube samples increased with the increase of glass fibre. All of samples exhibited ductile stress strain curve as they had a yield point and a fracture point. The ductile ToughSkin yield characteristics are very important as sudden brittle failure is considered unsafe for mining practices

Using microtechnology to quantify torso angle during match-play in field hockey

Warman, GE, Cole, MH, Johnston, RD, Chalkley, D, and Pepping, GJ. Using microtechnology to quantify torso angle during match-play in field hockey. J Strength Cond Res 33(10): 2648–2654, 2019—Field hockey is played in a dynamic environment placing specific postural demands on athletes. Little research has been devoted to understanding the nature of a player's torso postures in field hockey match-play and its relationship with the perceptuomotor demands of the sport. We used commercially available microtechnology worn by 16 athletes during a 6-match national tournament to quantify torso flexion/extension angles. Orientation was derived using the inertial and magnetic sensors housed within global positioning system devices, assessing torso angle in the sagittal plane from 91 individual match files. The main independent variable was playing position, whereas the dependent variable was torso flexion/extension, presented as a percentage of playing time spent in 15 × 10° torso postural bands ranging from ≥40° extension to ≥90° flexion. It was shown that athletes spent 89.26% of their playing time in various torso postures, ranging from 20 to 90° of flexion. Defenders spent more time than midfielders (p = 0.004, effect size [ES] = 0.43) and strikers (p = 0.004; ES = 0.44) in the posture band of 10–20° torso flexion, whereas midfielders spent more time between 20 and 30° of torso flexion (p = 0.05; ES = 0.32) than strikers. Conversely, strikers spent more time between 30 and 40° of flexion than defenders (p < 0.001; ES = 0.74). These results reflect the sport-specific and role-specific torso angles adopted by field hockey athletes during match-play. Coaching staff can use these data to gain insight into the postural demands of their sport and inform the preparation of athletes for the perception-action demands of competition

Sliding mode control of spatial mechanical systems decoupling translation and rotation

This paper looks at the robust trajectory control of spatial mechanical systems using sliding mode techniques. Two distinctions of the proposed method from reported methods are: (1) The measure of attitudinal error used is intrinsically defined, Euclidean-geometric, and intuitive. From Euler's theorem it follows that given a desired and actual attitude of a rigid body there exists an axis and angle of rotation relating the two attitudes. This defines a relative rotation vector, which is used as an intrinsically defined, intuitive measure of error. Reported methods use algebraic differences of entities such as generalized coordinates representing attitude. While functionally correlated to attitudinal error, these measures are not intrinsically defined. (2) A novel, dynamically nonlinear sliding function is used that results in a simple control law. The parameters of this function are dynamically and geometrically intuitive. Simulation results are given for a spacecraft tracking a complex desired trajectory

Enhanced ion transport using geometrically structured charge selective interfaces

A microfluidic platform containing charged hydrogels is used to investigate the effect of geometry on charge transport in electrodialysis applications. The influence of heterogeneity on ion transport is determined by electrical characterization and fluorescence microscopy of three different hydrogel geometries. We found that electroosmotic transport of ions towards the hydrogel is enhanced in heterogeneous geometries, as a result of the inhomogeneous electric field in these systems. This yields higher ionic currents for equal applied potentials when compared to homogeneous geometries. The contribution of electroosmotic transport is present in all current regimes, including the Ohmic regime. We also found that the onset of the overlimiting current occurs at lower potentials due to the increased heterogeneity in hydrogel shape, owing to the non-uniform electric field distribution in these systems. Pinning of ion depletion and enrichment zones is observed in the heterogeneous hydrogel systems, due to electroosmotic flows and electrokinetic instabilities. Our platform is highly versatile for the rapid investigation of the effects of membrane topology on general electrodialysis characteristics, including the formation of ion depletion zones on the micro-scale and the onset of the overlimiting current