This study examined the often contrived advertising claims of the manufacturers of variable resistance isotonic machinery. Specifically, the study sought to ascertain whether certain equipment was compatible with musculo-skeletal and perceptual needs and limitations of the human user: that is, to determine whether presently installed eccentric cams, which provide the variable resistance, matched the users force curves. The format of this research was in the ergonomic tradition in which empirical research is not necessarily the primary avenue. Consequently the inter-disciplinary nature of ergonomics required small-scale laboratory- simulation experiments to be conducted in a diverse range of disciplines such as physiology, psychology and biomechanics. It was found that on all five pieces of variable resistance machinery analysed, a mismatch between the force curves and the eccentric cams exist. The cams were redesigned accordingly. The metabolic cost of performing fixed-rate isoinertial lifts was moderate. The psychophysical analysis revealed that perceptual responses indicated that the work was classified as 'light' and only at 30% stress levels do local cues begin to dominate. Based on these findings it was concluded that manufacturers advertising claims in the instances analysed were not well-founded and that variable resistance isotonic machinery should only be used to develop muscular strength and endurance, and do not effectively serve as weight-loss devices.

Electromyographic (EMG) activity versus bite force was studied during a gradually increased isometric contraction up to maximal effort for patients with painful masseter muscles and referents. The masseter muscle, the anterior temporal muscle and the descending part of the trapezius muscle were chosen for the recordings. Bite force was registered with a bite force sensor placed between the first molars. The effects of double blind intramuscular injections of lidocaine and saline in the patients' masseter muscle were evaluated by EMG versus bite force and by assessments of discomfort. EMG activity during unilateral chewing was compared in terms of relative masticatory force between referents and patients by amplitude probability distribution analysis. Regression analyses showed intra-individually steeper slopes for high force levels than for low force levels for the masseter muscle. This was not observed for the anterior temporal muscle. These differences in slopes of the EMG versus force regressions for the masseter muscle and the anterior temporal muscle could be due to differences in recruitment pattern. The same intra-individual relationship between low and high force levels was found for referents and patients. An increased activity, especially among the patients, was found for the descending part of the trapezius muscle during stronger activity of the mandibular elevators. The EMG versus force relationship for low force levels of the masseter muscle was less steep after an intramuscular injection of lidocaine but not after saline. Both solutions for injection had a positive effect on the patients' assessments of discomfort one week after the injection. Three days after injection the patients who received lidocaine experienced a reduction in muscular discomfort. This reduction was not found among patients receiving saline. The amplitude probability distribution analysis revealed that the patients used greater relative masticatory forces than the referents during the chewing of an almond for all probability levels analysed below the peak load of the masseter muscles. Rough estimates of the peak masticatory forces in Newton (N) were for chewing an almond 364 N (referents); 373 N (patients) and for gum-chewing 239 N (referents); 238 N (patients) as regards the masseter muscle. The values were similar for the anterior temporal muscle. / digitalisering@umu

Neuromuscular control is believed to play an essential role during dynamic knee joint stabilisation. Evaluation of voluntary muscle action can be delineated as support strategies against external loading moments (Lloyd & Buchanan, 2001). The aim of this study was to determine if males and females exhibit differences in knee muscle action and cocontraction during voluntary isometric closed kinetic chain force generation in various directions in the horizontal plane representative of applied loads transverse to the long axis of the shank. Twenty-six healthy young adults (13 male, 13 female) stood with their dominant leg in a boot fixed to a force platform. A force target matching protocol required subjects to position a cursor (projected on a video screen) over a target and maintain the position for one second. To control the cursor, loads were applied against the force platform with their dominant leg to produce various combinations of anterior-posterior, medial-lateral loads while maintaining constant inferior-superior loads. A successful target match required a normalised force magnitude of equal effort for each subject and target location which triggered the recording of electromyography (EMG) for eight muscles crossing the knee joint. EMG was normalised to percent maximum voluntary isometric contraction. A mean magnitude of muscle activation, mean direction of muscle activation and a muscle specificity index was determined using EMG vectors. In addition, cocontraction indices were also computed for antagonist muscle pairs. Based on similar previous research, it was hypothesised that females would have greater quadriceps and hamstrings coactivation, greater muscle activation magnitudes, lower specificity for the quadriceps than males and no difference in hamstring characteristics. In our study, females significantly cocontracted their vastus lateralis and lateral gastrocnemius muscles to a greater degree than males (p=0.001). No significant differences were observed across sexes for the cocontraction of quadriceps and hamstrings or the lateral quadriceps and gastrocnemius muscles. Females displayed significantly lower specificity than males in their semitendinosus (p=0.025) and tensor fascia lata (p=0.012) activity patterns, greater magnitude of muscle activation in their lateral gastrocnemius (p=0.002) and tensor fascia lata (p<0.003) and no statistical difference in the other muscles. Furthermore, the activation patterns in our study grossly differed from previous open kinetic chain force target matching. These findings indicate that healthy young males and females have differences in their knee muscle control strategies and that knee muscle recruitment patterns differ during weight bearing and non-weight bearing tasks.

Convex cycles play a role e.g. in the context of product graphs. We introduce convex cycle bases and describe a polynomial-time algorithm that recognizes whether a given graph has a convex cycle basis and provides an explicit construction in the positive case. Relations between convex cycles bases and other types of cycles bases are discussed. In particular we show that if G has a unique minimal cycle bases, this basis is convex. Furthermore, we characterize a class of graphs with convex cycles bases that includes partial cubes and hence median graphs.

Neste trabalho estudamos o problema relacionado à construção de uma teoria quântica para uma partícula, se movendo não relativisticamente num espaço curvo, tratado como uma subvariedade de outro Euclideano, talvez dando maior ênfase ao aspecto geométrico envolvido nesta abordagem, uma vez que os demais trabalhos relacionados ao mesmo tema não o fazem. Além de mostrarmos que o consequente uso de uma teoria de sistemas vinculados não contribui para remover as ambiguidades da formulação quântica, relacionados diretamente ao ordenamento de operadores, também apresentamos, através de uma quantização específica feita sob a prescrição de Dirac, elementos que permitem não apenas construir um formalismo quântico covariante, mas também liberto de qualquer correção quântica. Em adição, fazemos alguns comentários gerais no que se refere às outras abordagens clássicas possíveis para o mesmo problema, intentando construir teorias quânticas associadas ao sistema sob consideração. / In this work we study the problem related to the construction of a quantum theory for a particle, moving non-relativistically in a curved space, treated as submanifold of the other Euclidean, maybe putting more emphasis on the geometric aspect envolved in this approach, since the rest of the works related to the subject do not. Besides showing that the consequent use of a theory of constrained systems not contributes for remove the ambiguities in the quantum formulation, related directly to the ordering of operators, we also showing, through a specific quantization made in the prescription of Dirac, elements that offers resources not only to construct a covariant quantum formalism, but also free from any quantum correction. In addition, we make some general comments in relation to other classical approaches possible for the same problem, attempting to build quantum theories associated with the system under consideration.

No description available.

No description available.

The purpose of this study was to examine the effect of post-resistance exercise alcohol ingestion on LPS-stimulated production of IFNγ, TNF-α, IL-1β, IL-6, IL-8, and IL-10. Recreationally resistance-trained men (n = 10, 25 ± 3 yr, 177 ± 7 cm, 83.8 ± 15.7 kg, 14.8 ± 8.5% body fat) and women (n = 8, 23 ± 2 yr, 161 ± 3 cm, 59.5 ± 6.0 kg, 26.5 ± 3.0% body fat) completed the study. Participants visited the laboratory for an initial visit at which time they were screened, familiarized with procedures, and had their 1-repetition maximum (1RM) back squat tested. Subsequently, participants visited the laboratory 2 more times and completed 2 identical heavy resistance exercise bouts (6 sets of 10 repetitions of 80% 1RM back squat) after which a beverage, either containing alcohol (alcohol condition, ALC; 1.09 g EtOH per kg fat free mass) or water (placebo condition, PLA), was administered. Blood samples were collected before exercise (PRE), and at 3 hours (3h) and 5 hours (5h) after exercise. Samples were stimulated with lipopolysaccharide (LPS) and cultured overnight. Supernatant was collected and analyzed for IFNγ, TNF-α, IL-1β, IL-6, IL-8, and IL-10. A significant (p < 0.05) main effect for time was found for IFNγ, TNF-α, and IL-1β (5h greater than PRE) and for IL-10 (5h less than PRE and 3h, 3h less than PRE). An interaction effect was found for IL-8 (ALC less than PLA at 5h) and for IL-6 (ALC greater than PLA at PRE and ALC less than PLA at 3h). For IL-6, ALC was less at 3h than at PRE, and PLA was greater at 3h than at PRE. Overall, the LPS-stimulated cytokine response was pro-inflammatory by 5h. Alcohol consumed after heavy resistance exercise reduced LPS-stimulated production of IL-6 and IL-8 but not of IFNγ, TNF-α, IL-1β, or IL-10. These data indicate that alcohol affected inflammatory capacity but that the potential effect of alcohol on the production of cytokines in response to LPS was largely overwhelmed by the resistance exercise bout.

Une classe de graphes est close par mineurs si, pour tout graphe dans la classe et tout mineur de ce graphe, le mineur est ́egalement dans la classe. Par un fameux th ́eor`eme de Robertson et Seymour, nous savons que car- act ́eriser une telle classe peut ˆetre fait `a l’aide d’un nombre fini de mineurs exclus minimaux. Ceux-ci sont des graphes qui n’appartiennent pas `a la classe et qui sont minimaux dans le sens des mineurs pour cette propri ́et ́e.Dans cette thèse, nous étudions trois problèmes à propos de classes de graphes closes par mineurs. Les deux premiers sont reliés à la caractérisation de certaines classes de graphes, alors que le troisième étudie une relation de “packing-covering” dans des graphes excluant un mineur.Pour le premier problème, nous étudions des plongements isométriques de graphes dont les arêtes sont pondérées dans des espaces métriques. Principalement, nous nous intêressons aux espaces ell_2 et ell_∞. E ́tant donné un graphe pondéré, un plongement isométrique associe à chaque sommet du graphe un vecteur dans l’autre espace de sorte que pour chaque arête du graphe le poids de celle-ci est égal à la distance entre les vecteurs correspondant à ses sommets. Nous disons qu’une fonction de poids sur les arêtes est une fonction de distances réalisable s’il existe un tel plongement. Le paramètre f_p(G) détermine la dimension k minimale d’un espace ell_p telle que toute fonction de distances réalisable de G peut être plongée dans ell_p^k. Ce paramètre est monotone dans le sens des mineurs. Nous caractérisons les graphes tels que f_p(G) a une grande valeur en termes de mineurs inévitables pour p = 2 et p = ∞. Une famille de graphes donne des mineurs inévitables pour un invariant monotone pour les mineurs, si ces graphes “expliquent” pourquoi l’invariant est grand.Le deuxième problème étudie les mineurs exclus minimaux pour la classe de graphes avec φ(G) borné par une constante k, où φ(G) est un paramètre lié au dominant des coupes d’un graphe G. Ce polyèdre contient tous les points qui, composante par composante, sont plus grands ou égaux à une combination convexe des vecteurs d’incidence de coupes dans G. Le paramètre φ(G) est égal au membre de droite maximum d’une description linéaire du dominant des coupes de G en forme entière minimale. Nous étudions les mineurs exclus minimaux pour la propriété φ(G) <= 4 et montrons une nouvelle borne sur φ(G) en termes du “vertex cover number”.Le dernier problème est d’un autre type. Nous étudions une relation de “packing-covering” dans les classes de graphes excluant un mineur. Étant donné un graphe G, une boule de centre v et de rayon r est l’ensemble de tous les sommets de G qui sont à distance au plus r de v. Pour un graphe G et une collection de boules donnés nous pouvons définir un hypergraphe H dont les sommets sont ceux de G et les arêtes correspondent aux boules de la collection. Il est bien connu que dans l’hypergraphe H, le “transversal number” τ(H) vaut au moins le “packing number” ν(H). Nous montrons une borne supérieure sur ν(H) qui est linéaire en τ(H), résolvant ainsi un problème ouvert de Chepoi, Estellon et Vaxès. / A class of graphs is closed under taking minors if for each graph in the class and each minor of this graph, the minor is also in the class. By a famous result of Robertson and Seymour, we know that characterizing such a class can be done by identifying a finite set of minimal excluded minors, that is, graphs which do not belong to the class and are minor-minimal for this property.In this thesis, we study three problems in minor-closed classes of graphs. The first two are related to the characterization of some graph classes, while the third one studies a packing-covering relation for graphs excluding a minor.In the first problem, we study isometric embeddings of edge-weighted graphs into metric spaces. In particular, we consider ell_2- and ell_∞-spaces. Given a weighted graph, an isometric embedding maps the vertices of this graph to vectors such that for each edge of the graph the weight of the edge equals the distance between the vectors representing its ends. We say that a weight function on the edges of the graph is a realizable distance function if such an embedding exists. The minor-monotone parameter f_p(G) determines the minimum dimension k of an ell_p-space such that any realizable distance function of G is realizable in ell_p^k. We characterize graphs with large f_p(G) value in terms of unavoidable minors for p = 2 and p = ∞. Roughly speaking, a family of graphs gives unavoidable minors for a minor-monotone parameter if these graphs “explain” why the parameter is high.The second problem studies the minimal excluded minors of the class of graphs such that φ(G) is bounded by some constant k, where φ(G) is a parameter related to the cut dominant of a graph G. This unbounded polyhedron contains all points that are componentwise larger than or equal to a convex combination of incidence vectors of cuts in G. The parameter φ(G) is equal to the maximum right-hand side of a facet-defining inequality of the cut dominant of G in minimum integer form. We study minimal excluded graphs for the property φ(G) <= 4 and provide also a new bound of φ(G) in terms of the vertex cover number.The last problem has a different flavor as it studies a packing-covering relation in classes of graphs excluding a minor. Given a graph G, a ball of center v and radius r is the set of all vertices in G that are at distance at most r from v. Given a graph and a collection of balls, we can define a hypergraph H such that its vertices are the vertices of G and its edges correspond to the balls in the collection. It is well-known that, in the hypergraph H, the transversal number τ(H) is at least the packing number ν(H). We show that we can bound τ(H) from above by a linear function of ν(H) for every graphs G and ball collections H if the graph G excludes a minor, solving an open problem by Chepoi, Estellon et Vaxès. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

The purpose of this project was to further elucidate the effects post-exercise alcohol ingestion. This project had many novel aspects including using a resistance exercise (RE) only exercise design and the inclusion of women. To our knowledge, we are the first to investigate the effect of post-RE alcohol ingestion in women. In the first chapter of this project, information on the prevalence of alcohol use and the importance of skeletal muscle as a dynamic and metabolic tissue was provided. In chapter two, the effects of post-RE alcohol ingestion in men and women are detailed. The major findings of this study was that although RE elicited similar mTORC1 signaling both in men and in women, alcohol ingestion appeared to only attenuate RE-induced phosphorylation of the mTORC1 signaling pathway in men. The third chapter focused on examining the effects of post-RE alcohol ingestion on acute testosterone bioavailability. The primary findings of this study was that alcohol substantially elevated serum total and free testosterone concentrations during recovery from a bout of resistance exercise. The fourth chapter detailed factors that contribute to bone density in men. The major findings of this study was that young adult male long-distance runners who participated in resistance training at least once per week had greater bone mineral density than their non-resistance trained and non-exercise trained peers.