Selbstkontrolle und Handlungsinitiierung

Gemäß den Annahmen des Kraftspeichermodells der Selbstkontrolle basiert die Fähigkeit, eigene Impulse zu kontrollieren, auf einer limitierten Ressource, die vorübergehend erschöpfen kann. Während dieses Erschöpfungszustandes können anschließende Selbstkontrollhandlungen weniger erfolgreich ausgeführt werden. Die Regulation des Impulses, einen Sprint möglichst zeitnah zu einem akustischen Startsignal zu initiieren, erfordert Selbstkontrolle. Daher testeten wir an einer Stichprobe aus N = 37 Sportstudierenden die Annahme, dass die Initiierung von Sprints in Leichtathletik von der momentan verfügbaren Selbstkontrollkraft abhängt. Zur Untersuchung dieser Fragestellung führten die Versuchspersonen zunächst zu T1 drei Sprints über ca. 20 Meter aus einem Startblock aus und mittels Kontaktplatten wurde die Reaktionszeit (in Millisekunden) gemessen, die die Versuchspersonen benötigten, um den Sprint nach einem akustischen Signal zu initiieren. Im Anschluss daran wurde die temporär verfügbare Selbstkontrollkraft mittels einer Abschreibaufgabe experimentell manipuliert: Die Versuchspersonen wurden zufällig einer Ego Depletion Bedingung zugeordnet, in der die Selbstkontrollkraft temporär erschöpft wurde oder einer Kontrollgruppe, in der die Selbstkontrollkraft intakt gehalten wurde. Im Anschluss daran zu T2 wurden die Versuchspersonen erneut gebeten, drei Sprints über ca. 20 Meter auszuführen und die Reaktionszeiten wurden wieder mittels Kontaktplatten erfasst. Die Ergebnisse einer mixed between (Ego Depletion, kein Ego Depletion) within (T1, T2) Varianzanalyse unterstützen unsere Hypothese, so dass in der Ego Depletion Bedingung die Reaktionszeiten von T1 (M = 0.35, SD = 0.03) zu T2 signifikant zunahmen (M = 0.38, SD = 0.04), F(1, 35) = 6.77, p = .01, η2partial = .16, wohingegen sich in der Kontrollgruppe keine statistisch bedeutsamen Veränderungen der Reaktionszeiten zeigten (T1: M = 0.36, SD = 0.03; T2: M = 0.35, SD = 0.04), F(1, 35) = 0.47, p = .50, η2partial = .01. Eine Stärkung der Selbstkontrollkraft könnte Athleten dabei helfen, ihr Leistungsoptimum abzurufen.

Synthesis of photo-crosslinking probes and their application for the site-selective chemical modification of the 5-HT3 receptor

The 5-HT3 receptor (5-HT3R) is an important ion channel responsible for the transmission of nerve impulses in the CNS and PNS that is activated by the endogenous agonist serotonin (5-hydroxytryptamine, 5-HT). 5-HT3R is the only serotonin receptor belonging to the Cys-loop superfamily of neurotransmitter receptors. Different structural biology approaches can be applied, such as crystallization and x-ray analysis. Nonetheless, characterizing the exact ligand binding site(s) of these dynamic receptors is still challenging. The use of photo-crosslinking probes is an alternative validated approach allowing identification of regions in the protein that are important for the binding of small molecules. We designed our probes based on the core structure of the 5-HT3R antagonist granisetron, a FDA approved drug used for the treatment of chemotherapy-induced nausea and vomiting. We synthesized a small library of photo-crosslinking probes by conjugating diazirines and benzophenones via various linkers to granisetron. We were able to obtain several compounds with diverse linker lengths and different photo-crosslinking moieties that show nanomolar binding affinity for the orthosteric binding site. Furthermore we established a stable h5-HT3R expressing cell line and a purification protocol to yield the receptor in a high purity. Several experiments showed unambiguously that we are able to photo-crosslink our probes with the receptor site-specifically. The functionalised protein was analysed by Western blot and MS-analysis. This yielded the exact covalent modification site, corroborating current ligand binding models derived from mutagenesis and docking studies.

The video head impulse test during post-rotatory nystagmus: physiology and clinical implications.

The aim of this study was to test the effects of a sustained nystagmus on the head impulse response of the vestibulo-ocular reflex (VOR) in healthy subjects. VOR gain (slow-phase eye velocity/head velocity) was measured using video head impulse test goggles. Acting as a surrogate for a spontaneous nystagmus (SN), a post-rotatory nystagmus (PRN) was elicited after a sustained, constant-velocity rotation, and then head impulses were applied. 'Raw' VOR gain, uncorrected for PRN, in healthy subjects in response to head impulses with peak velocities in the range of 150°/s-250°/s was significantly increased (as reflected in an increase in the slope of the gain versus head velocity relationship) after inducing PRN with slow phases of nystagmus of high intensity (>30°/s) in the same but not in the opposite direction as the slow-phase response induced by the head impulses. The values of VOR gain themselves, however, remained in the normal range with slow-phase velocities of PRN < 30°/s. Finally, quick phases of PRN were suppressed during the first 20-160 ms of a head impulse; the time frame of suppression depended on the direction of PRN but not on the duration of the head impulse. Our results in normal subjects suggest that VOR gains measured using head impulses may have to be corrected for any superimposed SN when the slow-phase velocity of nystagmus is relatively high and the peak velocity of the head movements is relatively low. The suppression of quick phases during head impulses may help to improve steady fixation during rapid head movements.

Compensatory saccades benefit from prediction during head impulse testing in early recovery from vestibular deafferentation

The head impulse test (HIT) can identify a deficient vestibulo-ocular reflex (VOR) by the compensatory saccade (CS) generated once the head stops moving. The inward HIT is considered safer than the outward HIT, yet might have an oculomotor advantage given that the subject would presumably know the direction of head rotation. Here, we compare CS latencies following inward (presumed predictable) and outward (more unpredictable) HITs after acute unilateral vestibular nerve deafferentation. Seven patients received inward and outward HITs delivered at six consecutive postoperative days (POD) and again at POD 30. All head impulses were recorded by portable video-oculography. CS included those occurring during (covert) or after (overt) head rotation. Inward HITs included mean CS latencies (183.48 ms ± 4.47 SE) that were consistently shorter than those generated during outward HITs in the first 6 POD (p = 0.0033). Inward HITs induced more covert saccades compared to outward HITs, acutely. However, by POD 30 there were no longer any differences in latencies or proportions of CS and direction of head rotation. Patients with acute unilateral vestibular loss likely use predictive cues of head direction to elicit early CS to keep the image centered on the fovea. In acute vestibular hypofunction, inwardly applied HITs may risk a preponderance of covert saccades, yet this difference largely disappears within 30 days. Advantages of inwardly applied HITs are discussed and must be balanced against the risk of a false-negative HIT interpretation.

A new class of symbolic abstract neural nets

Starting from the way the inter-cellular communication takes place by means of protein channels and also from the standard knowledge about neuron functioning, we propose a computing model called a tissue P system, which processes symbols in a multiset rewriting sense, in a net of cells similar to a neural net. Each cell has a finite state memory, processes multisets of symbol-impulses, and can send impulses (?excitations?) to the neighboring cells. Such cell nets are shown to be rather powerful: they can simulate a Turing machine even when using a small number of cells, each of them having a small number of states. Moreover, in the case when each cell works in the maximal manner and it can excite all the cells to which it can send impulses, then one can easily solve the Hamiltonian Path Problem in linear time. A new characterization of the Parikh images of ET0L languages are also obtained in this framework.

Solving SAT in linear time with a neural-like membrane system

We present in this paper a neural-like membrane system solving the SAT problem in linear time. These neural Psystems are nets of cells working with multisets. Each cell has a finite state memory, processes multisets of symbol-impulses, and can send impulses (?excitations?) to the neighboring cells. The maximal mode of rules application and the replicative mode of communication between cells are at the core of the eficiency of these systems.

Measurements and Prediction of Pedestrian Walking Loads on an Aluminium Catwalk

During the last two decades the topic of human induced vibration has attracted a lot of attention among civil engineering practitioners and academics alike. Usually this type of problem may be encountered in pedestrian footbridges or floors of paperless offices. Slender designs are becoming increasingly popular, and as a consequence, the importance of paying attention to vibration serviceability also increases. This paper resumes the results obtained from measurements taken at different points of an aluminium catwalk which is 6 m in length by 0.6 m in width. Measurements were carried out when subjecting the structure to different actions:1)Static test: a steel cylinder of 35 kg was placed in the middle of the catwalk; 2)Dynamic test: this test consists of exciting the structure with singles impulses; 3)Dynamic test: people walking on the catwalk. Identification of the mechanical properties of the structure is an achievement of the paper. Indirect methods were used to estimate properties including the support stiffness, the beam bending stiffness, the mass of the structure (using Rayleigh method and iterative matrix method), the natural frequency (using the time domain and frequency domain analysis) and the damping ratio (by calculating the logarithmic decrement). Experimental results and numerical predictions for the response of an aluminium catwalk subjected to walking loads have been compared. The damping of this light weight structure depends on the amplitude of vibration which complicates the tuning of a structural model. In the light of the results obtained it seems that the used walking load model is not appropriate as the predicted transient vibration values (TTVs) are much higher than the measured ones.

Habitar lo irreal. aproximaciones a una arquitectónica de los mundos virtuales

Lo virtual es el lugar donde todo empieza, el germen de la imaginación productiva, un ámbito de pulsiones inaugurales y preexistencias sin forma donde todo convive, a la espera de ser diferenciado. Lo virtual es el sitio donde nacen las primeras exploraciones de cualquier acto de concepción, incluida la creación artística o el proyectar arquitectónico. Sin embargo, en las últimas tres décadas de revolución digital, el término ha sido utilizado de forma abusiva para referirse a todo tipo de entornos simulados informáticamente, es decir, a ficciones cerradas, programadas, controladas por el software y sus rutinas, radicalmente actualizadas, acabadas, completas, formalizadas. Paradójicamente, lo virtual ha servido para nombrar construcciones profundamente anti-virtuales. La telemática está propiciando el acceso del ser humano a un nuevo tipo de irrealidad cotidiana sustentada en prácticas espaciales cada vez menos vinculadas con la física y la biología. Esta condición fantasmagórica del habitar digital exige nuevos espacios de diálogo entre arquitectura y tecnología que se centren en el hecho imaginario. Para ello esta tesis propone —a partir de la recuperación del término griego arquitectónica— llevar el alcance de la disciplina hasta el hecho global del habitar. Y, al mismo tiempo, devolver al adjetivo virtual su auténtico significado preliminar, entendiendo que los verdaderos mundos virtuales no pueden simular nada, representar nada, formalizar nada, porque ellos son el origen infinito y amorfo de todo mundo. ABSTRACT The virtual is where it all starts, the seed of productive imagination, an area of inaugural impulses and formless preexistences that beat together, waiting to be differentiated. The virtual is the birthplace of any creative exploration, including those of the architectural project. However, in the last three decades of digital revolution, the term has been mostly misused to refer to all types of computer simulated environments; shut, finished, complete, formalized, radically actualized fictions controlled by software routines. Paradoxically, the virtual has been giving name to profoundly anti-virtual constructions. Telematics is allowing humans to access to a new kind of unreality, based on everyday spatial practices that are increasingly detached from physics and biology. This spectral condition of the digital living demands new dialectics between architecture and technology, focused on the imaginary. This thesis proposes — beginning by recovering the Greek word architectonics— to extend the scope of the discipline beyond edification to the overall fact of inhabiting. And, at the same time, to return to the adjective virtual its authentic preliminary meaning, realizing that the true virtual worlds cannot simulate, represent or formalize anything because they are the amorphous and endless source of every world.

Acoustic characterization of open cavities with the image source model

El objetivo de esta tesis es investigar las resonancias acústicas de una cavidad abierta tridimensional, de paredes rectas o inclinadas, mediante un método rápido y eficiente en el dominio del tiempo. Este método modela la respuesta temporal en cualquier punto como la convolución de la forma de onda de la fuente con la respuesta impulsiva de la cavidad, la cual se obtiene como una secuencia de impulsos retardados y atenuados procedentes de la fuente real, el primero, y de las fuentes imágenes especulares, los siguientes (Modelo Fuente Imagen, ISM). Además de las componentes directa y reflejadas en las paredes, la respuesta impulsiva también incluye las contribuciones difractadas en los bordes, obtenidas mediante la generación de las componentes difractadas de cada fuente imagen. Las frecuencias de resonancia acústica de la cavidad abierta son extraídas de los picos de la Función de Respuesta en Frecuencia (FRF), obtenida como la transformada de Fourier de la respuesta temporal correspondiente entre una fuente puntual y un punto cualquiera de la cavidad. Las frecuencias de resonancia acústicas estimadas mediante este Método de Fuentes Imagen + difracción en bordes son validadas por comparación con las que proporciona un Modelo de Elementos Finitos (FEM) y con las medidas experimentalmente, con diferencias menores que el 1.6 % y el 2.7 %, respectivamente. A modo de comparación, las frecuencias de resonancia estimadas para la misma cavidad por el método ISM, cuando no se incluye la difracción en los bordes, difieren en un 5.7 % de las obtenidas experimentalmente. ABSTRACT The goal of this thesis is to investigate the acoustic resonances of a three-dimensional open cavity, with parallel and non-parallel walls, by a fast and efficient method in the time domain. This method models the time response in any point as the convolution of the source waveform with the impulse response of the cavity, which, in turn, is obtained as a sequence of attenuated and delayed impulses coming, the first from the real, and the subsequent from the mirror imaged sources (Image Source Model). Besides direct and wall-reflected components, the impulse response includes also edge-diffracted contributions by generating first order diffraction components for each image source. The acoustic resonance frequencies of the open cavity are extracted from the peaks of the Frequency Response Function (FRF), obtained as the Fourier transform of the corresponding time response between a point source and any point in the cavity. The acoustic resonance frequencies estimated by the Image Source Model + edge diffraction are validated by comparison with those provided by a Finite Element Model (FEM) and the ones measured experimentally, differing less than 1.6 % and 2.7 %, respectively. As a comparison, resonance frequencies estimated with the pure Image Source Model differ by 5.7 % from the measured ones.

ESTUDO DA EFICÁCIA ADAPTATIVA DE HERDEIROS DE EMPRESA FAMILIAR

O presente trabalho visa estudar a eficácia adaptativa dos herdeiros de empresa familiar, segundo a teoria da adaptação de Ryad Simon. Os objetivos foram: 1. investigar a eficácia adaptativa dos herdeiros de empresa familiar; 2. descrever aspectos da dinâmica adaptativa dos herdeiros; 3. descrever aspectos da dinâmica familiar internalizada pelos herdeiros de cada família; 4. investigar as repercussões obtidas pela análise da eficácia adaptativa de cada herdeiro no contexto da empresa familiar. O método utilizado foi clínico e a técnica, a entrevista clínica preventiva. Foram entrevistados sete herdeiros de duas diferentes empresas familiar, todos os herdeiros atuam profissionalmente nelas. Os dados das entrevistas foram avaliados clinicamente por meio da Escala Diagnóstica Adaptativa Operacionalizada (EDAO), e análise dos fatores, segundo Teoria da Evolução da Adaptação, de Ryad Simon. Os resultados encontrados foram: 72% (5 herdeiros) encontraram-se classificados no grupo 4 Adaptação Ineficaz Severa, 14% (1 herdeiro) no grupo 5 Adaptação Ineficaz Grave, e 14% (1herdeiro) no grupo 3 Adaptação Ineficaz Moderada em CRISE. Na análise destes resultados verificou-se a importância central do setor Afetivo-Relacional, 100% dos herdeiros foram classificados com respostas pouquíssimo adequadas, e o que mesclou as diferentes classificações, descritas acima, foi no setor Produtividade. Frente a este diagnóstico percebemos a importância das relações com a figura paterna, presente tanto no lar como na empresa. Na análise dos herdeiros e da dinâmica das duas famílias concluímos que quando a figura paterna comporta-se de forma onipotente e insubstituível, não permite que os filhos cresçam e busquem satisfação no que produzem. Diferente de quando este pai consegue colocar limites, mas gradativamente delega responsabilidades aos filhos, demonstrando confiar neles. Esta postura facilita o encontro da satisfação na área produtiva. Neste estudo ficou evidente que a dinâmica familiar estende-se até a empresarial, desta forma em uma das famílias, cujo pai foi capaz de delegar aos filhos o poder na empresa, a dinâmica na empresa parece ser saudável, permeada por impulsos construtivos. Enquanto a outra, cujo pai mantém o poder na empresa, parece estar muito doente, predominando os impulsos destrutivos na família com repercussão, também, na empresa.

ESTUDO DA EFICÁCIA ADAPTATIVA DE HERDEIROS DE EMPRESA FAMILIAR

O presente trabalho visa estudar a eficácia adaptativa dos herdeiros de empresa familiar, segundo a teoria da adaptação de Ryad Simon. Os objetivos foram: 1. investigar a eficácia adaptativa dos herdeiros de empresa familiar; 2. descrever aspectos da dinâmica adaptativa dos herdeiros; 3. descrever aspectos da dinâmica familiar internalizada pelos herdeiros de cada família; 4. investigar as repercussões obtidas pela análise da eficácia adaptativa de cada herdeiro no contexto da empresa familiar. O método utilizado foi clínico e a técnica, a entrevista clínica preventiva. Foram entrevistados sete herdeiros de duas diferentes empresas familiar, todos os herdeiros atuam profissionalmente nelas. Os dados das entrevistas foram avaliados clinicamente por meio da Escala Diagnóstica Adaptativa Operacionalizada (EDAO), e análise dos fatores, segundo Teoria da Evolução da Adaptação, de Ryad Simon. Os resultados encontrados foram: 72% (5 herdeiros) encontraram-se classificados no grupo 4 Adaptação Ineficaz Severa, 14% (1 herdeiro) no grupo 5 Adaptação Ineficaz Grave, e 14% (1herdeiro) no grupo 3 Adaptação Ineficaz Moderada em CRISE. Na análise destes resultados verificou-se a importância central do setor Afetivo-Relacional, 100% dos herdeiros foram classificados com respostas pouquíssimo adequadas, e o que mesclou as diferentes classificações, descritas acima, foi no setor Produtividade. Frente a este diagnóstico percebemos a importância das relações com a figura paterna, presente tanto no lar como na empresa. Na análise dos herdeiros e da dinâmica das duas famílias concluímos que quando a figura paterna comporta-se de forma onipotente e insubstituível, não permite que os filhos cresçam e busquem satisfação no que produzem. Diferente de quando este pai consegue colocar limites, mas gradativamente delega responsabilidades aos filhos, demonstrando confiar neles. Esta postura facilita o encontro da satisfação na área produtiva. Neste estudo ficou evidente que a dinâmica familiar estende-se até a empresarial, desta forma em uma das famílias, cujo pai foi capaz de delegar aos filhos o poder na empresa, a dinâmica na empresa parece ser saudável, permeada por impulsos construtivos. Enquanto a outra, cujo pai mantém o poder na empresa, parece estar muito doente, predominando os impulsos destrutivos na família com repercussão, também, na empresa.

Probes bound to myosin Cys-707 rotate during length transients in contraction

It is widely conjectured that muscle shortens because portions of myosin molecules (the “cross-bridges”) impel the actin filament to which they transiently attach and that the impulses result from rotation of the cross-bridges. Crystallography indicates that a cross-bridge is articulated–consisting of a globular catalytic/actin-binding domain and a long lever arm that may rotate. Conveniently, a rhodamine probe with detectable attitude can be attached between the globular domain and the lever arm, enabling the observer to tell whether the anchoring region rotates. Well-established signature effects observed in shortening are tension changes resulting from the sudden release or quick stretch of active muscle fibers. In this investigation we found that closely correlated with such tension changes are changes in the attitude of the rhodamine probes. This correlation strongly supports the conjecture about how shortening is achieved.

Induction of Purkinje fiber differentiation by coronary arterialization

A synchronized heart beat is controlled by pacemaking impulses conducted through Purkinje fibers. In chicks, these impulse-conducting cells are recruited during embryogenesis from myocytes in direct association with developing coronary arteries. In culture, the vascular cytokine endothelin converts embryonic myocytes to Purkinje cells, implying that selection of conduction phenotype may be mediated by an instructive cue from arteries. To investigate this hypothesis, coronary arterial development in the chicken embryo was either inhibited by neural crest ablation or activated by ectopic expression of fibroblast growth factor (FGF). Ablation of cardiac neural crest resulted in ≈70% reductions (P < 0.01) in the density of intramural coronary arteries and associated Purkinje fibers. Activation of coronary arterial branching was induced by retrovirus-mediated overexpression of FGF. At sites of FGF-induced hypervascularization, ectopic Purkinje fibers differentiated adjacent to newly induced coronary arteries. Our data indicate the necessity and sufficiency of developing arterial bed for converting a juxtaposed myocyte into a Purkinje fiber cell and provide evidence for an inductive function for arteriogenesis in heart development distinct from its role in establishing coronary blood circulation.

RetinaStudio: A bioinspired framework to encode visual information

The retina is a very complex neural structure, which performs spatial, temporal, and chromatic processing on visual information and converts it into a compact ‘digital’ format composed of neural impulses. This paper presents a new compiler-based framework able to describe, simulate and validate custom retina models. The framework is compatible with the most usual neural recording and analysis tools, taking advantage of the interoperability with these kinds of applications. Furthermore it is possible to compile the code to generate accelerated versions of the visual processing models compatible with COTS microprocessors, FPGAs or GPUs. The whole system represents an ongoing work to design and develop a functional visual neuroprosthesis. Several case studies are described to assess the effectiveness and usefulness of the framework.

Development of a magnetic resonance compatible wrist device for the analysis of movement encoding in the brain

Tese de mestrado integrado em Engenharia Biomédica e Biofísica, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2016