The content and nature of thought

Die Dissertation prüft das Potential von Fines Semantischem Relationismus für einen kognivistischen Ansatz der Sprache und des Geistes. Hauptziel ist es, den Semantischen Relationismus als einzig angemessene Inhalstheorie für die Gedankensprache zu verteidigen, indem die Vorzüge gegenüber den wichtigsten Alternativen, dem Referentialismus und dem Fregeanismus, aufgezeigt werden. Die Arbeit soll zeigen, dass nur der Semantische Relatinismus alle Varianten des Frege Puzzles für die Gedankensprache lösen kann, und zwar in einerWeise, die die erheblichen Schwierigkeiten der alternativen Theorien umgeht. Das Ergebnis ist sowohl eine Verteidigung des Sematischen Relationismus als auch eine Bestätigung der Tragbarkeit der Hypothese einer Gedankensprache. Auf Basis der Gedankensprache und einer relationistischen Semantik stellt die Arbeit zudem eine neue Theorie der Propositionen vor, die sich erheblich von allen bestehenden Alternativen, inbegriffen der von Fine, unterscheidet. Das Endergebnis ist eine Auffassung von Propositionen als syntaktisch strukturierten mentalen Repräsentationen, die Sätze in der Gedankensprache darstellen, sowie Träger von Inhalten, die durch ihren semantischen Inhalt typindividuiert sind. Ein Kernziel der Arbeit ist es, die Vorteile dieser Auffassung gegenüber klassischen und modernen Alternativen aufzuzeigen. Die Arbeit entwickelt ihr Gesamtergebnis durch die Aufarbeitung von drei aktuellen, eng miteinander verbundenen Debatten. Erstens, das Problem, dass Freges Puzzle für Gedanken und überzegungen darstellt, insbesondere in Form von Kripkes Puzzle. Zweitens, das Problem der Typindividuierung von Symbolen in der Gedankensprache. Drittens, die Debatte um die Ontologie von Begriffen und Propositionen. Indem eine vielversprechende relationistische Lösung in diesen Problembereichen entwickelt wird, bietet die Arbeit zusätzliche Bestätigung für Fines semantische Theorie durch eine erhebliche Erweiterung ihres Anwendungsbereichs.The thesis evaluates the potential of Fine’s Semantic Relationism for a cognitivist approach to language and the mind. The main aim is to champion Semantic Relationism as the only adequate theory of content for the Language of Thought by bringing out the benefits of the theory over its main rivals, Referentialism and Fregeanism. It seeks to show that only Semantic Relationism can address all the variants of Frege’s Puzzle for the Language of Thought, and that it can do so in a way that avoids the substantial difficulties that beset other semantic theories. The main outcome is at the same time a vindication of the adopted semantic theory and a confirmation of the viability of the Language of Thought hypothesis. The thesis also offers a new theory of propositions on the basis of the Language of Thought and a Relationist semantics that differs significantly from all such presently available theories, including Fine’s. The final result is a theory of propositions as syntactically structured mental representations, which are sentences in the Language of Thought, that are content bearers individuated by their semantic content as specified by Semantic Relationism. A major objective of the thesis is to highlight the advantages of this view over both classical and current alternatives. The thesis develops its overall view by offering solutions in three closely related ongoing debates. First, the challenge posed by Frege’s Puzzle for thought and belief, Kripke’s Puzzle notably included, secondly, the problem about the proper type-individuation of Language of Thought symbol tokens, and thirdly, the debate about the ontological nature of concepts and propositions. By developing a promising Relationist response to these problems, the thesis also provides additional support to Fine’s semantic theory by considerably expanding its scope of application

Shotgun approaches to gait analysis:insights & limitations

Background: Identifying features for gait classification is a formidable problem. The number of candidate measures is legion. This calls for proper, objective criteria when ranking their relevance.Methods: Following a shotgun approach we determined a plenitude of kinematic and physiological gait measures and ranked their relevance using conventional analysis of variance (ANOVA) supplemented by logistic and partial least squares (PLS) regressions. We illustrated this approach using data from two studies involving stroke patients, amputees, and healthy controls.Results: Only a handful of measures turned out significant in the ANOVAs. The logistic regressions, by contrast, revealed various measures that clearly discriminated between experimental groups and conditions. The PLS regression also identified several discriminating measures, but they did not always agree with those of the logistic regression.Discussion &amp; conclusion: Extracting a measure's classification capacity cannot solely rely on its statistical validity but typically requires proper post-hoc analysis. However, choosing the latter inevitably introduces some arbitrariness, which may affect outcome in general. We hence advocate the use of generic expert systems, possibly based on machine-learning.</p

Differentiation between solid-ankle cushioned heel and energy storage and return prosthetic foot based on step-to-step transition cost

Decreased push-off power by the prosthetic foot and inadequate roll-over shape of the foot have been shown to increase the energy dissipated during the step-to-step transition in human walking. The aim of this study was to determine whether energy storage and return (ESAR) feet are able to reduce the mechanical energy dissipated during the step-to-step transition. Fifteen males with a unilateral lower-limb amputation walked with their prescribed ESAR foot (Vari-Flex, Ossur; Reykjavík, Iceland) and with a solid-ankle cushioned heel foot (SACH) (1D10, Ottobock; Duderstadt, Germany), while ground reaction forces and kinematics were recorded. The positive mechanical work on the center of mass performed by the trailing prosthetic limb was larger (33%, p = 0.01) and the negative work performed by the leading intact limb was lower (13%, p = 0.04) when walking with the ESAR foot compared with the SACH foot. The reduced step-to-step transition cost coincided with a higher mechanical push-off power generated by the ESAR foot and an extended forward progression of the center of pressure under the prosthetic ESAR foot. Results can explain the proposed improvement in walking economy with this kind of energy storing and return prosthetic foot

Energy storing and return prosthetic feet improve step length symmetry while preserving margins of stability in persons with transtibial amputation

Abstract Background Energy storing and return (ESAR) feet are generally preferred over solid ankle cushioned heel (SACH) feet by people with a lower limb amputation. While ESAR feet have been shown to have only limited effect on gait economy, other functional benefits should account for this preference. A simple biomechanical model suggests that enhanced gait stability and gait symmetry could prove to explain part of the difference in the subjective preference between both feet. Aim To investigate whether increased push-off power with ESAR feet increases center of mass velocity at push off and enhance intact step length and step length symmetry while preserving the margin of stability during walking in people with a transtibial prosthesis. Methods Fifteen people with a unilateral transtibial amputation walked with their prescribed ESAR foot and a SACH foot at a fixed walking speed (1.2 m/s) over a level walkway while kinematic and kinetic data were collected. Push-off work generated by the foot, center of mass velocity, step length, step length symmetry and backward margin of stability were assessed and compared between feet. Results Push-off work was significantly higher when using the ESAR foot compared to the SACH foot. Simultaneously, center of mass velocity at toe-off was higher with ESAR compared to SACH, and intact step length and step length symmetry increased without reducing the backward margin of stability. Conclusion Compared to the SACH foot, the ESAR foot allowed an improvement of step length symmetry while preserving the backward margin of stability at community ambulation speed. These benefits may possibly contribute to the subjective preference for ESAR feet in people with a lower limb amputation

Feasibility and Validity of a Graded One-Legged Cycle Exercise Test to Determine Peak Aerobic Capacity in Older People With a Lower-Limb Amputation

Background. Information concerning exercise tolerance and aerobic capacity is imperative for generating effective and safe exercise programs. However, for older people with a lower-limb amputation, a standard exercise test is not available. Objective. The primary aim of the present study was to determine whether a graded 1-legged peak exercise test is feasible and provides a valid assessment of peak aerobic capacity in older people walking with a lower-limb prosthesis. Design. This was a quasi-experimental case-control study. Methods. A total of 36 older people with a lower-limb prosthesis and 21 people who were able-bodied (controls) (overall mean age=61.7 years, SD=6.1) performed a discontinuous graded 1-legged exercise test. The peak respiratory exchange ratio was used as an indicator of maximal effort. The controls performed an additional 2-legged exercise test to provide insight into differences between the testing modes. Results. All participants were able to perform the exercise test. Electrocardiographic tracings and blood pressure were adequately monitored. The controls and the people with a lower-limb amputation were able to stress the cardiovascular system to a similar extent. Analyses of construct validity revealed that the peak aerobic capacity measured with the 1-legged exercise test was able to distinguish between participants on the basis of age, body mass index, and sex to a similar extent as the conventional 2-legged exercise test. Limitations. The results can be generalized only to people who are able to ambulate with their prosthesis. Conclusions. The graded 1-legged exercise test was feasible and provided a valid assessment of peak aerobic capacity and exercise tolerance in older people walking with a lower-limb prosthesis

Relation Between Aerobic Capacity and Walking Ability in Older Adults With a Lower-Limb Amputation

<p>Objectives: To determine the relative aerobic load, walking speed, and walking economy of older adults with a lower-limb prosthesis, and to predict the effect of an increased aerobic capacity on their walking ability.</p><p>Design: Cross-sectional.</p><p>Setting: Human motion laboratory at a rehabilitation center.</p><p>Participants: Convenience sample of older adults (n=36) who underwent lower-limb amputation because of vascular deficiency or trauma and able-bodied controls (n=21).</p><p>Interventions: Not applicable.</p><p>Main Outcome Measures: Peak aerobic capacity and oxygen consumption while walking were determined. The relative aerobic load and walking economy were assessed as a function of walking speed, and a data-based model was constructed to predict the effect of an increased aerobic capacity on walking ability.</p><p>Results: People with a vascular amputation walked at a substantially higher (45.2%) relative aerobic load than people with an amputation because of trauma. The preferred walking speed in both groups of amputees was slower than that of able-bodied controls and below their most economical walking speed. We predicted that a 10% increase in peak aerobic capacity could potentially result in a reduction in the relative aerobic load of 9.1%, an increase in walking speed of 17.3% and 13.9%, and an improvement in the walking economy of 6.8% and 2.9%, for people after a vascular or traumatic amputation, respectively.</p><p>Conclusions: Current findings corroborate the notion that, especially in people with a vascular amputation, the peak aerobic capacity is an important determinant for walking ability. The data provide quantitative predictions on the effect of aerobic training; however, future research is needed to experimentally confirm these predictions. (C) 2013 by the American Congress of Rehabilitation Medicine</p>

Cardiorespiratory fitness and physical strain during prosthetic rehabilitation after lower limb amputation

Background: Sufficient cardiorespiratory fitness has been regarded a prerequisite for prosthetic walking. In order to improve cardiorespiratory fitness, adequate strain ought to be placed on the system during training. Objectives: To determine cardiorespiratory fitness at the start and end of inpatient rehabilitation after lower limb amputation and determine the physical strain experienced during conventional prosthetic rehabilitation. Study design: Multicenter prospective cohort study. Methods: Cardiorespiratory fitness was assessed using a peak one-legged cycle exercise test. Physical strain was assessed during a minimum of three full rehabilitation days using heart rate recordings. Physical strain was expressed in the time per day that heart rate exceeded 40% of heart rate reserve. Results: At the start of rehabilitation, peak aerobic capacity was on average 16.9 (SD, 6.5) mL/kg/min (n = 33). Overall, peak aerobic capacity did not improve over the course of rehabilitation (n = 23, p = 0.464). Fifty percent of the patients experienced a physical strain level that satisfies minimum criteria for maintaining cardiorespiratory fitness (>40% heart rate reserve for 30 min/day). Conclusion: Cardiorespiratory fitness was low and did not increase during conventional prosthetic rehabilitation. On average, the physical strain during rehabilitation was insufficient to elicit potential improvements in aerobic capacity. Results stress the need for dedicated physical training modules at the individual level. Clinical relevance: This study shows that clinicians ought to be aware of the relatively low cardiorespiratory fitness of people who have undergone lower limb amputation and that improvements during rehabilitation are not always obtained. Results stress the need for physical training modules in which intensity is imposed at the individual level

A photoswitchable strapped calix[4]pyrrole receptor: highly effective chloride binding and release

A stiff-stilbene strapped calix[4]pyrrole receptor can be reversibly switched by light between a strong chloride-binding Z-isomer and a very weakly binding E-isomer. The light-induced switching process is monitored by UV-Vis and (1)H NMR spectroscopy and chloride binding is studied in detail using both (1)H NMR and ITC titrations in DMSO and MeCN. In DMSO, at millimolar concentrations, switching from a fully bound to an almost fully unbound state can be triggered. Quantification of the binding constants in MeCN reveals an extraordinary 8000-fold affinity difference between the Z- and E-isomer. Single crystal X-ray crystallographic analysis gives insight into the structure of the photogenerated E-isomer and the geometry of the chloride-bound receptors is optimized by DFT calculations. The highly effective control of binding affinity demonstrated in this work opens up new prospects for on demand binding and release in extractions and photocontrol of membrane transport processes, among other applications