Investigation of escape response of Norwegian Pecten maximus

The ongoing process of ocean acidification already affects marine life and, according to the concept of oxygen- and capacity limitation of thermal tolerance (OCLTT), these effects may be exacerbated at the boarders of the thermal tolerance window. We studied the effects of elevated CO2 concentrations on clapping performance and energy metabolism of the commercially important scallop Pecten maximus. Individuals were exposed for at least 30 days to 4°C (winter) or to 10°C (spring/summer) at either ambient (0.04 kPa, normocapnia) or predicted future PCO2 levels (0.11 kPa, hypercapnia). Cold (4°C) exposed groups revealed thermal stress exacerbated by PCO2 indicated by a high mortality overall and its increase from 55% under normocapnia to 90% under hypercapnia. We therefore excluded the 4°C groups from further experimentation. Scallops at 10°C showed impaired clapping performance following hypercapnic exposure. Force production was significantly reduced although the number of claps was unchanged between normo- and hypercapnia exposed scallops. The difference between maximal and resting metabolic rate (aerobic scope) of the hypercapnic scallops was significantly reduced compared to normocapnic animals, indicating a reduction in net aerobic scope. Our data confirm that ocean acidification narrows the thermal tolerance range of scallops resulting in elevated vulnerability to temperature extremes and impairs the animal's performance capacity with potentially detrimental consequences for its fitness and survival in the ocean of tomorrow.

Perception de la force musculaire et de la distribution du poids lors d’activités motrices chez le sujet sain

Les résultats de récentes études supportent l’idée que la perception de la force aurait un rôle important dans la réalisation des tâches fonctionnelles telles que le passage assis à debout (PAD). Cependant, très peu d’études se sont attardées à quantifier la précision avec laquelle les individus en santé sont capables de percevoir la force musculaire. De plus, aucune étude n’a évalué la perception de la distribution du poids lors du PAD chez la clientèle saine. L’objectif principal était de recueillir des données sur la capacité des individus en santé, jeunes et âgés, à percevoir la force musculaire lors d’une contraction statique des extenseurs du genou et à percevoir la distribution du poids (DP) lorsqu’ils réalisent le passage assis à debout. Cette étude a été effectuée auprès de 31 individus, divisés en deux groupes d’âge (< 50 ans et > 60 ans). Les résultats du premier objectif visant à quantifier les erreurs de perception de la force lors d’une contraction statique des extenseurs du genou ont démontré que les erreurs absolues et brutes sont plus élevées pour les niveaux de force supérieurs à 50 % CVM et que les erreurs brutes sont plus importantes chez les jeunes pour les hauts niveaux de force. Les résultats du second objectif visant à évaluer l’effet de différentes références sensorimotrices sur les erreurs de perception de la force musculaire ont montré qu’une référence à 50 % CVM préalablement montrée au participant et qu’une contraction simultanée des muscles de la préhension de la main diminuent les erreurs brutes et absolues de perception pour le niveau de force 70%. Les résultats du troisième objectif visant à quantifier les erreurs de perception de la DP lors du PAD ont démontré que les sujets jeunes et âgés ont une bonne capacité à percevoir leur DP avec des erreurs absolues et brutes variant respectivement entre 2,9 % et 9,4 % et entre -5,7 % et 5,7 % et des coefficients de corrélations intra-classes supérieurs à 0,75 entre la DP produite et celle perçue. Les résultats contribuent à approfondir les connaissances relatives à la perception de la force et de la DP chez les individus en santé. Ces données pourront servir à titre comparatif lors d’études menées auprès des patients hémiparétiques afin d’évaluer s’ils ont des problèmes perceptifs pouvant expliquer l’asymétrie récurrente qu’ils présentent dans leurs tâches fonctionnelles.

Revealing atomic-scale details in the force fields above carbonate surfaces

Diese Arbeit stellt eine ausführliche Studie fundamentaler Eigenschaften der Kalzit CaCO3(10.4) und verwandter Mineraloberflächen dar, welche nicht nur durch die Verwendung von Nichtkontakt Rasterkraftmikroskopie, sondern hauptsächlich durch die Messung von Kraftfeldern ermöglicht wurde. Die absolute Oberflächenorientierung sowie der hierfür zugrundeliegende Prozess auf atomarer Skala konnten erfolgreich für die Kalzit (10.4) Oberfläche identifiziert werden.rnDie Adsorption chiraler Moleküle auf Kalzit ist relevant im Bereich der Biomineralisation, was ein Verständnis der Oberflächensymmetrie unumgänglich macht. Die Messung des Oberflächenkraftfeldes auf atomarer Ebene ist hierfür ein zentraler Aspekt. Eine solche Kraftkarte beleuchtet nicht nur die für die Biomineralisation wichtige Wechselwirkung der Oberfläche mit Molekülen, sondern enthält auch die Möglichkeit, Prozesse auf atomarer Skala und damit Oberflächeneigenschaften zu identifizieren.rnDie Einführung eines höchst flexiblen Messprotokolls gewährleistet die zuverlässige und kommerziell nicht erhältliche Messung des Oberflächenkraftfeldes. Die Konversion der rohen ∆f Daten in die vertikale Kraft Fz ist jedoch kein trivialer Vorgang, insbesondere wenn Glätten der Daten in Frage kommt. Diese Arbeit beschreibt detailreich, wie Fz korrekt für die experimentellen Bedingungen dieser Arbeit berechnet werden können. Weiterhin ist beschrieben, wie Lateralkräfte Fy und Dissipation Γ erhalten wurden, um das volle Potential dieser Messmethode auszureizen.rnUm Prozesse auf atomarer Skala auf Oberflächen zu verstehen sind die kurzreichweitigen, chemischen Kräfte Fz,SR von größter Wichtigkeit. Langreichweitige Beiträge müssen hierzu an Fz angefittet und davon abgezogen werden. Dies ist jedoch eine fehleranfällige Aufgabe, die in dieser Arbeit dadurch gemeistert werden konnte, dass drei unabhängige Kriterien gefunden wurden, die den Beginn zcut von Fz,SR bestimmen, was für diese Aufgabe von zentraler Bedeutung ist. Eine ausführliche Fehleranalyse zeigt, dass als Kriterium die Abweichung der lateralen Kräfte voneinander vertrauenswürdige Fz,SR liefert. Dies ist das erste Mal, dass in einer Studie ein Kriterium für die Bestimmung von zcut gegeben werden konnte, vervollständigt mit einer detailreichen Fehleranalyse.rnMit der Kenntniss von Fz,SR und Fy war es möglich, eine der fundamentalen Eigenschaften der CaCO3(10.4) Oberfläche zu identifizieren: die absolute Oberflächenorientierung. Eine starke Verkippung der abgebildeten Objekte

Corticospinal output and loss of force during motor fatigue

The objective of this study was to analyze central motor output changes in relation to contraction force during motor fatigue. The triple stimulation technique (TST, Magistris et al. in Brain 121(Pt 3):437-450, 1998) was used to quantify a central conduction index (CCI = amplitude ratio of central conduction response and peripheral nerve response, obtained simultaneously by the TST). The CCI removes effects of peripheral fatigue from the quantification. It allows a quantification of the percentage of the entire target muscle motor unit pool driven to discharge by a transcranial magnetic stimulus. Subjects (n = 23) performed repetitive maximal voluntary contractions (MVC) of abductor digiti minimi (duration 1 s, frequency 0.5 Hz) during 2 min. TST recordings were obtained every 15 s, using stimulation intensities sufficient to stimulate all cortical motor neurons (MNs) leading to the target muscle, and during voluntary contractions of 20% of the MVC to facilitate the responses. TST was also repetitively recorded during recovery. This basic exercise protocol was modified in a number of experiments to further characterize influences on CCI of motor fatigue (4 min exercise at 50% MVC; delayed fatigue recovery during local hemostasis, "stimulated exercise" by 20 Hz trains of 1 s duration at 0.5 Hz during 2 min). In addition, the cortical silent period was measured during the basic exercise protocol. Force fatigued to approximately 40% of MVC in all experiments and in all subjects. In all subjects, CCI decreased during exercise, but this decrease varied markedly between subjects. On average, CCI reductions preceded force reductions during exercise, and CCI recovery preceded force recovery. Exercising at 50% for 4 min reduced muscle force more markedly than CCI. Hemostasis induced by a cuff delayed muscle force recovery, but not CCI recovery. Stimulated exercise reduced force markedly, but CCI decreased only marginally. Summarized, force reduction and reduction of the CCI related poorly quantitatively and in time, and voluntary drive was particularly critical to reduce the CCI. The fatigue induced reduction of CCI may result from a central inhibitory phenomenon. Voluntary muscle activation is critical for the CCI reduction, suggesting a primarily supraspinal mechanism.

Photo- and Thermo-Chromic Study of the Ethylenediamine Trimolybdate

The ethylenediamine trimolybdate (ENTMo) can show unusually photochromic and thermochromic properties and there exists in the difference of chromic mechanisms, which has been proved in our previous work [I]. In this paper, X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) and laser Raman spectroscopy (LRS) of the colored samples are characterized and analyzed in detail. The crystal structure, the inorganic skeleton and the microenvironment of center ions of the colored samples do not substantively change except distortion. The color difference of the photochromic and the thermochromic samples is discussed and that the difference of reduction sites result in their different chromic mechanisms is suggested.

The effect of implant design on insertion torque and immediate micromotion

Objectives: To evaluate the effect of insertion torque on micromotion to a lateral force in three different implant designs. Material and methods: Thirty-six implants with identical thread design, but different cutting groove design were divided in three groups: (1) non-fluted (no cutting groove, solid screw-form); (2) fluted (901 cut at the apex, tap design); and (3) Blossomt (Patent pending) (non-fluted with engineered trimmed thread design). The implants were screwed into polyurethane foam blocks and the insertion torque was recorded after each turn of 901 by a digital torque gauge. Controlled lateral loads of 10N followed by increments of 5 up to 100N were sequentially applied by a digital force gauge on a titanium abutment. Statistical comparison was performed with two-way mixed model ANOVA that evaluated implant design group, linear effects of turns and displacement loads, and their interaction. Results: While insertion torque increased as a function of number of turns for each design, the slope and final values increased (Po0.001) progressively from the Blossomt to the fluted to the non-fluted design (M +/- standard deviation [SD] = 64.1 +/- 26.8, 139.4 +/- 17.2, and 205.23 +/- 24.3 Ncm, respectively). While a linear relationship between horizontal displacement and lateral force was observed for each design, the slope and maximal displacement increased (Po0.001) progressively from the Blossomt to the fluted to the non-fluted design (M +/- SD 530 +/- 57.7, 585.9 +/- 82.4, and 782.33 +/- 269.4 mm, respectively). There was negligible to moderate levels of association between insertion torque and lateral displacement in the Blossomt, fluted and non-fluted design groups, respectively. Conclusion: Insertion torque was reduced in implant macrodesigns that incorporated cutting edges, and lesser insertion torque was generally associated with decreased micromovement. However, insertion torque and micromotion were unrelated within implant designs, particularly for those designs showing the least insertion torque.

Kinetics of martensitic phase decomposition in the Cu-10wt.%Al alloy with Ag additions

The study of the kinetics of martensitic phase decomposition in the Cu-10wt.%Al alloy with Ag additions showed that the presence of Ag retarded the eutectoid decomposition reaction and enhanced martensite stabilization. This stabilization effect was attributed to Ag atoms redistribution as structure defects, increase in the numbers of Cu-Al pairs due to Ag-Al interaction and the Al atoms redistribution around one Cu atom at the sub-lattice of the martensitic crystal. © 2008 Trans Tech Publications.

Avaliação dinamométrica e eletromiográfica do quadril em idosas caidoras e não caidoras

Pós-graduação em Desenvolvimento Humano e Tecnologias - IBRC

Comparação da análise miográfica sonora com a força muscular

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeitos de dois programas periodizados de exercícios resistidos sobre parâmetros funcional, clínico e biológico em mulheres jovens sedentárias

Pós-graduação em Fisioterapia - FCT

The effect of implant design on insertion torque and immediate micromotion

Objectives: To evaluate the effect of insertion torque on micromotion to a lateral force in three different implant designs. Material and methods: Thirty-six implants with identical thread design, but different cutting groove design were divided in three groups: (1) non-fluted (no cutting groove, solid screw-form); (2) fluted (901 cut at the apex, tap design); and (3) Blossomt (Patent pending) (non-fluted with engineered trimmed thread design). The implants were screwed into polyurethane foam blocks and the insertion torque was recorded after each turn of 901 by a digital torque gauge. Controlled lateral loads of 10N followed by increments of 5 up to 100N were sequentially applied by a digital force gauge on a titanium abutment. Statistical comparison was performed with two-way mixed model ANOVA that evaluated implant design group, linear effects of turns and displacement loads, and their interaction. Results: While insertion torque increased as a function of number of turns for each design, the slope and final values increased (Po0.001) progressively from the Blossomt to the fluted to the non-fluted design (M +/- standard deviation [SD] = 64.1 +/- 26.8, 139.4 +/- 17.2, and 205.23 +/- 24.3 Ncm, respectively). While a linear relationship between horizontal displacement and lateral force was observed for each design, the slope and maximal displacement increased (Po0.001) progressively from the Blossomt to the fluted to the non-fluted design (M +/- SD 530 +/- 57.7, 585.9 +/- 82.4, and 782.33 +/- 269.4 mm, respectively). There was negligible to moderate levels of association between insertion torque and lateral displacement in the Blossomt, fluted and non-fluted design groups, respectively. Conclusion: Insertion torque was reduced in implant macrodesigns that incorporated cutting edges, and lesser insertion torque was generally associated with decreased micromovement. However, insertion torque and micromotion were unrelated within implant designs, particularly for those designs showing the least insertion torque.

Multivariate analysis in the maximum strength performance

This study performed an exploratory analysis of the anthropometrical and morphological muscle variables related to the one-repetition maximum (1RM) performance. In addition, the capacity of these variables to predict the force production was analyzed. 50 active males were submitted to the experimental procedures: vastus lateralis muscle biopsy, quadriceps magnetic resonance imaging, body mass assessment and 1RM test in the leg-press exercise. K-means cluster analysis was performed after obtaining the body mass, sum of the left and right quadriceps muscle cross-sectional area (Sigma CSA), percentage of the type II fibers and the 1RM performance. The number of clusters was defined a priori and then were labeled as high strength performance (HSP1RM) group and low strength performance (LSP1RM) group. Stepwise multiple regressions were performed by means of body mass, Sigma CSA, percentage of the type II fibers and clusters as predictors' variables and 1RM performance as response variable. The clusters mean +/- SD were: 292.8 +/- 52.1 kg, 84.7 +/- 17.9 kg, 19249.7 +/- 1645.5 mm(2) and 50.8 +/- 7.2% for the HSP1RM and 254.0 +/- 51.1 kg, 69.2 +/- 8.1 kg, 15483.1 +/- 1 104.8 mm(2) and 51.7 +/- 6.2 %, for the LSP1RM in the 1RM, body mass, Sigma CSA and muscle fiber type II percentage, respectively. The most important variable in the clusters division was the Sigma CSA. In addition, the Sigma CSA and muscle fiber type II percentage explained the variance in the 1RM performance (Adj R-2 = 0.35, p = 0.0001) for all participants and for the LSP1RM (Adj R-2 = 0.25, p = 0.002). For the HSP1RM, only the Sigma CSA was entered in the model and showed the highest capacity to explain the variance in the 1RM performance (Adj R-2 = 0.38, p = 0.01). As a conclusion, the muscle CSA was the most relevant variable to predict force production in individuals with no strength training background.

Effect of laser soldering irradiation on covalent bonds of pure collagen

Laser tissue welding and soldering is being increasingly used in the clinical setting for defined surgical procedures. The exact induced changes responsible for tensile strength are not yet fully investigated. To further improve the strength of the bonding, a better understanding of the laser impact at the subcellular level is necessary. The goal of this study was to analyze whether the effect of laser irradiation on covalent bonding in pure collagen using irradiances typically applied for tissue soldering. Pure rabbit and equine type I collagen were subjected to laser irradiation. In the first part of the study, rabbit and equine collagen were compared using identical laser and irradiation settings. In the second part of the study, equine collagen was irradiated at increasing laser powers. Changes in covalent bonding were studied indirectly using the sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) technique. Tensile strengths of soldered membranes were measured with a calibrated tensile force gauge. In the first experiment, no differences between the species-specific collagen bands were noted, and no changes in banding were found on SDS-PAGE after laser irradiation. In the second experiment, increasing laser irradiation power showed no effect on collagen banding in SDS-PAGE. Finally, the laser tissue soldering of pure collagen membranes showed virtually no determinable tensile strength. Laser irradiation of pure collagen at typical power settings and exposure times generally used in laser tissue soldering does not induce covalent bonding between collagen molecules. This is true for both rabbit and equine collagen proveniences. Furthermore, soldering of pure collagen membranes without additional cellular components does not achieve the typical tensile strength reported in native, cell-rich tissues. This study is a first step in a better understanding of laser impact at the molecular level and might prove useful in engineering of combined collagen-soldering matrix membranes for special laser soldering applications.