999 resultados para Reaching movement


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Citrus leprosis, caused by Citrus leprosis virus C (CiLV-C), is currently considered the most important viral disease in the Brazilian citrus industry due to the high costs required for the chemical control of its vector, the mite Brevipalpus phoenicis. The pathogen induces a non-systemic infection and the disease is characterized by the appearance of localized lesions on citrus leaves, stems and fruits, premature fruit and leaf drop and dieback of stems. Attempts were made to promote in vitro expression of the putative cell-to-cell movement protein of CiLV-C in Escherichia coli and to produce a specific polyclonal antibody against this protein as a tool to investigate the virus-plant-vector relationship. The antibody reacted strongly with the homologous protein expressed in vitro by ELISA, but poorly with the native protein present in leaf lesion extracts from sweet orange caused by CiLV-C. Reactions from old lesions were more intense than those from young lesions. Western blot and in situ immunolocalization assays failed to detect the native protein. These results suggest low expression of the movement protein (MP) in host tissues. Moreover, it is possible that the conformation of the protein expressed in vitro and used to produce the antibody differs from that of the native MP, hindering a full recognition of the latter.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

There is no reason for Dentistry to use different terms for phenomena defined in Physics, the specific field in which concepts associated with forces are established and adapted. In place of pressure/tension, the compression/traction pair should be used. This study defines each one of these terms and justifies their use. Our contemporary world demands standardized criteria, methods, measures, concepts and terms to ensure that study protocols, results and applications are used in the same way in any country or area of human action.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The mechanisms of tissue changes induced by occlusal trauma are in no way comparable to orthodontic movement. In both events the primary cause is of a physical nature, but the forces delivered to dental tissues exhibit completely different characteristics in terms of intensity, duration, direction, distribution, frequency and form of uptake by periodontal tissues. Consequently, the tissue effects induced by occlusal trauma are different from orthodontic movement. It can be argued that occlusal trauma generates a pathological tissue injury in an attempt to adapt to new excessive functional demands. Orthodontic movement, in turn,performs physiological periodontal bone remodeling to change the position of the teeth in a well-planned manner, eventually restoring normalcy.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

USP scientific production. USP journals. USP Open Access Movement.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Aquaporins and Rh proteins can function as gas (CO2 and NH3) channels. The present study explores the urea, H2O, CO2, and NH3 permeability of the human urea transporter B (UT-B) (SLC14A1), expressed in Xenopus oocytes. We monitored urea uptake using [14C]urea and measured osmotic water permeability (Pf) using video microscopy. To obtain a semiquantitative measure of gas permeability, we used microelectrodes to record the maximum transient change in surface pH (∆pHS) caused by exposing oocytes to 5% CO2/33 mM HCO3- (pHS increase) or 0.5 mM NH3/NH4+ (pHS decrease). UT-B expression increased oocyte permeability to urea by >20-fold, and Pf by 8-fold vs. H2O-injected control oocytes. UT-B expression had no effect on the CO2-induced ∆pHS but doubled the NH3-induced ∆pHS. Phloretin reduced UT-B-dependent urea uptake (Jurea * ) by 45%, Pf * by 50%, and (- ∆pHS * )NH3 by 70%. p-Chloromercuribenzene sulfonate reduced Jurea * by 25%, Pf * by 30%, and (∆pHS * )NH3 by 100%. Molecular dynamics (MD) simulations of membrane-embedded models of UT-B identified the monomeric UT-B pores as the main conduction pathway for both H2O and NH3 and characterized the energetics associated with permeation of these species through the channel. Mutating each of two conserved threonines lining the monomeric urea pores reduced H2O and NH3 permeability. Our data confirm that UT-B has significant H2O permeability and for the first time demonstrate significant NH3 permeability. Thus the UTs become the third family of gas channels. Inhibitor and mutagenesis studies and results of MD simulations suggest that NH3 and H2O pass through the three monomeric urea channels in UT-B.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The cardiovascular regulation undergoes wide changes in the different states of sleepwake cycle. In particular, the relationship between spontaneous fluctuations in heart period and arterial pressure clearly shows differences between the two sleep states. In non rapid-eye-movement sleep, heart rhythm is under prevalent baroreflex control, whereas in rapid-eye-movement sleep central autonomic commands prevail (Zoccoli et al., 2001). Moreover, during rapid-eye-movement sleep the cardiovascular variables show wide fluctuations around their mean value. In particular, during rapid-eyemovement sleep, the arterial pressure shows phasic hypertensive events which are superimposed upon the tonic level of arterial pressure. These phasic increases in arterial pressure are accompanied by an increase in heart rate (Sei & Morita, 1996; Silvani et al., 2005). Thus, rapid-eye-movement sleep may represent an “autonomic stress test” for the cardiovascular system, able to unmask pathological patterns of cardiovascular regulation (Verrier et al. 2005), but this hypothesis has never been tested experimentally. The aim of this study was to investigate whether rapid-eye-movement sleep may reveal derangements in central autonomic cardiovascular control in an experimental model of essential hypertension. The study was performed in Spontaneously Hypertensive Rats, which represent the most widely used model of essential hypertension, and allow full control of genetic and environmental confounding factors. In particular, we analyzed the cardiovascular, electroencephalogram, and electromyogram changes associated with phasic hypertensive events during rapid-eyemovement sleep in Spontaneously Hypertensive Rats and in their genetic Wistar Kyoto control strain. Moreover, we studied also a group of Spontaneously Hypertensive Rats made phenotypically normotensive by means of a chronic treatment with an angiotensin converting enzyme inhibitor, the Enalapril maleate, from the age of four weeks to the end of the experiment. All rats were implanted with electrodes for electroencephalographic and electromyographic recordings and with an arterial catheter for arterial pressure measurement. After six days for postoperative recovery, the rats were studied for five days, at an age of ten weeks.The study indicated that the peak of mean arterial pressure increase during the phasic hypertensive events in rapid-eye-movement sleep did not differ significantly between Spontaneously Hypertensive Rats and Wistar Kyoto rats, while on the other hand Spontaneously Hypertensive Rats showed a reduced increase in the frequency of theta rhythm and a reduced tachicardia with respect to Wistar Kyoto rats. The same pattern of changes in mean arterial pressure, heart period, and theta frequency was observed between Spontaneously Hypertensive Rats and Spontaneously Hypertensive Rats treated with Enalapril maleate. Spontaneously Hypertensive Rats do not differ from Wistar Kyoto rats only in terms of arterial hypertension, but also due to multiple unknown genetic differences. Spontaneously Hypertensive Rats were developed by selective breeding of Wistar Kyoto rats based only on the level of arterial pressure. However, in this process, multiple genes possibly unrelated to hypertension may have been selected together with the genetic determinants of hypertension (Carley et al., 2000). This study indicated that Spontaneously Hypertensive Rats differ from Wistar Kyoto rats, but not from Spontaneously Hypertensive Rats treated with Enalapril maleate, in terms of arterial pH and theta frequency. This feature may be due to genetic determinants unrelated to hypertension. In sharp contrast, the persistence of differences in the peak of heart period decrease and the peak of theta frequency increase during phasic hypertensive events between Spontaneously Hypertensive Rats and Spontaneously Hypertensive Rats treated with Enalapril maleate demonstrates that the observed reduction in central autonomic control of the cardiovascular system in Spontaneously Hypertensive Rats is not an irreversible consequence of inherited genetic determinants. Rather, the comparison between Spontaneously Hypertensive Rats and Spontaneously Hypertensive Rats treated with Enalapril maleate indicates that the observed differences in central autonomic control are the result of the hypertension per se. This work supports the view that the study of cardiovascular regulation in sleep provides fundamental insight on the pathophysiology of hypertension, and may thus contribute to the understanding of this disease, which is a major health problem in European countries (Wolf-Maier et al., 2003) with its burden of cardiac, vascular, and renal complications.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The human movement analysis (HMA) aims to measure the abilities of a subject to stand or to walk. In the field of HMA, tests are daily performed in research laboratories, hospitals and clinics, aiming to diagnose a disease, distinguish between disease entities, monitor the progress of a treatment and predict the outcome of an intervention [Brand and Crowninshield, 1981; Brand, 1987; Baker, 2006]. To achieve these purposes, clinicians and researchers use measurement devices, like force platforms, stereophotogrammetric systems, accelerometers, baropodometric insoles, etc. This thesis focus on the force platform (FP) and in particular on the quality assessment of the FP data. The principal objective of our work was the design and the experimental validation of a portable system for the in situ calibration of FPs. The thesis is structured as follows: Chapter 1. Description of the physical principles used for the functioning of a FP: how these principles are used to create force transducers, such as strain gauges and piezoelectrics transducers. Then, description of the two category of FPs, three- and six-component, the signals acquisition (hardware structure), and the signals calibration. Finally, a brief description of the use of FPs in HMA, for balance or gait analysis. Chapter 2. Description of the inverse dynamics, the most common method used in the field of HMA. This method uses the signals measured by a FP to estimate kinetic quantities, such as joint forces and moments. The measures of these variables can not be taken directly, unless very invasive techniques; consequently these variables can only be estimated using indirect techniques, as the inverse dynamics. Finally, a brief description of the sources of error, present in the gait analysis. Chapter 3. State of the art in the FP calibration. The selected literature is divided in sections, each section describes: systems for the periodic control of the FP accuracy; systems for the error reduction in the FP signals; systems and procedures for the construction of a FP. In particular is detailed described a calibration system designed by our group, based on the theoretical method proposed by ?. This system was the “starting point” for the new system presented in this thesis. Chapter 4. Description of the new system, divided in its parts: 1) the algorithm; 2) the device; and 3) the calibration procedure, for the correct performing of the calibration process. The algorithm characteristics were optimized by a simulation approach, the results are here presented. In addiction, the different versions of the device are described. Chapter 5. Experimental validation of the new system, achieved by testing it on 4 commercial FPs. The effectiveness of the calibration was verified by measuring, before and after calibration, the accuracy of the FPs in measuring the center of pressure of an applied force. The new system can estimate local and global calibration matrices; by local and global calibration matrices, the non–linearity of the FPs was quantified and locally compensated. Further, a non–linear calibration is proposed. This calibration compensates the non– linear effect in the FP functioning, due to the bending of its upper plate. The experimental results are presented. Chapter 6. Influence of the FP calibration on the estimation of kinetic quantities, with the inverse dynamics approach. Chapter 7. The conclusions of this thesis are presented: need of a calibration of FPs and consequential enhancement in the kinetic data quality. Appendix: Calibration of the LC used in the presented system. Different calibration set–up of a 3D force transducer are presented, and is proposed the optimal set–up, with particular attention to the compensation of non–linearities. The optimal set–up is verified by experimental results.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

I Max Bill is an intense giornata of a big fresco. An analysis of the main social, artistic and cultural events throughout the twentieth century is needed in order to trace his career through his masterpieces and architectures. Some of the faces of this hypothetical mural painting are, among others, Le Corbusier, Walter Gropius, Ernesto Nathan Rogers, Kandinskij, Klee, Mondrian, Vatongerloo, Ignazio Silone, while the backcloth is given by artistic avant-gardes, Bauhaus, International Exhibitions, CIAM, war events, reconstruction, Milan Triennali, Venice Biennali, the School of Ulm. Architect, even though more known as painter, sculptor, designer and graphic artist, Max Bill attends the Bauhaus as a student in the years 1927-1929, and from this experience derives the main features of a rational, objective, constructive and non figurative art. His research is devoted to give his art a scientific methodology: each work proceeds from the analysis of a problem to the logical and always verifiable solution of the same problem. By means of composition elements (such as rhythm, seriality, theme and its variation, harmony and dissonance), he faces, with consistent results, themes apparently very distant from each other as the project for the H.f.G. or the design for a font. Mathematics are a constant reference frame as field of certainties, order, objectivity: ‘for Bill mathematics are never confined to a simple function: they represent a climate of spiritual certainties, and also the theme of non attempted in its purest state, objectivity of the sign and of the geometrical place, and at the same time restlessness of the infinity: Limited and Unlimited ’. In almost sixty years of activity, experiencing all artistic fields, Max Bill works, projects, designs, holds conferences and exhibitions in Europe, Asia and Americas, confronting himself with the most influencing personalities of the twentieth century. In such a vast scenery, the need to limit the investigation field combined with the necessity to address and analyse the unpublished and original aspect of Bill’s relations with Italy. The original contribution of the present research regards this particular ‘geographic delimitation’; in particular, beyond the deep cultural exchanges between Bill and a series of Milanese architects, most of all with Rogers, two main projects have been addressed: the realtà nuova at Milan Triennale in 1947, and the Contemporary Art Museum in Florence in 1980. It is important to note that these projects have not been previously investigated, and the former never appears in the sources either. These works, together with the most well-known ones, such as the projects for the VI and IX Triennale, and the Swiss pavilion for the Biennale, add important details to the reference frame of the relations which took place between Zurich and Milan. Most of the occasions for exchanges took part in between the Thirties and the Fifties, years during which Bill underwent a significant period of artistic growth. He meets the Swiss progressive architects and the Paris artists from the Abstraction-Création movement, enters the CIAM, collaborates with Le Corbusier to the third volume of his Complete Works, and in Milan he works and gets confronted with the events related to post-war reconstruction. In these years Bill defines his own working methodology, attaining an artistic maturity in his work. The present research investigates the mentioned time period, despite some necessary exceptions. II The official Max Bill bibliography is naturally wide, including spreading works along with ones more devoted to analytical investigation, mainly written in German and often translated into French and English (Max Bill himself published his works in three languages). Few works have been published in Italian and, excluding the catalogue of the Parma exhibition from 1977, they cannot be considered comprehensive. Many publications are exhibition catalogues, some of which include essays written by Max Bill himself, some others bring Bill’s comments in a educational-pedagogical approach, to accompany the observer towards a full understanding of the composition processes of his art works. Bill also left a great amount of theoretical speculations to encourage a critical reading of his works in the form of books edited or written by him, and essays published in ‘Werk’, magazine of the Swiss Werkbund, and other international reviews, among which Domus and Casabella. These three reviews have been important tools of analysis, since they include tracks of some of Max Bill’s architectural works. The architectural aspect is less investigated than the plastic and pictorial ones in all the main reference manuals on the subject: Benevolo, Tafuri and Dal Co, Frampton, Allenspach consider Max Bill as an artist proceeding in his work from Bauhaus in the Ulm experience . A first filing of his works was published in 2004 in the monographic issue of the Spanish magazine 2G, together with critical essays by Karin Gimmi, Stanislaus von Moos, Arthur Rüegg and Hans Frei, and in ‘Konkrete Architektur?’, again by Hans Frei. Moreover, the monographic essay on the Atelier Haus building by Arthur Rüegg from 1997, and the DPA 17 issue of the Catalonia Polytechnic with contributions of Carlos Martì, Bruno Reichlin and Ton Salvadò, the latter publication concentrating on a few Bill’s themes and architectures. An urge to studying and going in depth in Max Bill’s works was marked in 2008 by the centenary of his birth and by a recent rediscovery of Bill as initiator of the ‘minimalist’ tradition in Swiss architecture. Bill’s heirs are both very active in promoting exhibitions, researching and publishing. Jakob Bill, Max Bill’s son and painter himself, recently published a work on Bill’s experience in Bauhaus, and earlier on he had published an in-depth study on ‘Endless Ribbons’ sculptures. Angela Thomas Schmid, Bill’s wife and art historian, published in end 2008 the first volume of a biography on Max Bill and, together with the film maker Eric Schmid, produced a documentary film which was also presented at the last Locarno Film Festival. Both biography and documentary concentrate on Max Bill’s political involvement, from antifascism and 1968 protest movements to Bill experiences as Zurich Municipality councilman and member of the Swiss Confederation Parliament. In the present research, the bibliography includes also direct sources, such as interviews and original materials in the form of letters correspondence and graphic works together with related essays, kept in the max+binia+jakob bill stiftung archive in Zurich. III The results of the present research are organized into four main chapters, each of them subdivided into four parts. The first chapter concentrates on the research field, reasons, tools and methodologies employed, whereas the second one consists of a short biographical note organized by topics, introducing the subject of the research. The third chapter, which includes unpublished events, traces the historical and cultural frame with particular reference to the relations between Max Bill and the Italian scene, especially Milan and the architects Rogers and Baldessari around the Fifties, searching the themes and the keys for interpretation of Bill’s architectures and investigating the critical debate on the reviews and the plastic survey through sculpture. The fourth and last chapter examines four main architectures chosen on a geographical basis, all devoted to exhibition spaces, investigating Max Bill’s composition process related to the pictorial field. Paintings has surely been easier and faster to investigate and verify than the building field. A doctoral thesis discussed in Lausanne in 1977 investigating Max Bill’s plastic and pictorial works, provided a series of devices which were corrected and adapted for the definition of the interpretation grid for the composition structures of Bill’s main architectures. Four different tools are employed in the investigation of each work: a context analysis related to chapter three results; a specific theoretical essay by Max Bill briefly explaining his main theses, even though not directly linked to the very same work of art considered; the interpretation grid for the composition themes derived from a related pictorial work; the architecture drawing and digital three-dimensional model. The double analysis of the architectural and pictorial fields is functional to underlining the relation among the different elements of the composition process; the two fields, however, cannot be compared and they stay, in Max Bill’s works as in the present research, interdependent though self-sufficient. IV An important aspect of Max Bill production is self-referentiality: talking of Max Bill, also through Max Bill, as a need for coherence instead of a method limitation. Ernesto Nathan Rogers describes Bill as the last humanist, and his horizon is the known world but, as the ‘Concrete Art’ of which he is one of the main representatives, his production justifies itself: Max Bill not only found a method, but he autonomously re-wrote the ‘rules of the game’, derived timeless theoretical principles and verified them through a rich and interdisciplinary artistic production. The most recurrent words in the present research work are synthesis, unity, space and logic. These terms are part of Max Bill’s vocabulary and can be referred to his works. Similarly, graphic settings or analytical schemes in this research text referring to or commenting Bill’s architectural projects were drawn up keeping in mind the concise precision of his architectural design. As for Mies van der Rohe, it has been written that Max Bill took art to ‘zero degree’ reaching in this way a high complexity. His works are a synthesis of art: they conceptually encompass all previous and –considered their developments- most of contemporary pictures. Contents and message are generally explicitly declared in the title or in Bill’s essays on his artistic works and architectural projects: the beneficiary is invited to go through and re-build the process of synthesis generating the shape. In the course of the interview with the Milan artist Getulio Alviani, he tells how he would not write more than a page for an essay on Josef Albers: everything was already evident ‘on the surface’ and any additional sentence would be redundant. Two years after that interview, these pages attempt to decompose and single out the elements and processes connected with some of Max Bill’s works which, for their own origin, already contain all possible explanations and interpretations. The formal reduction in favour of contents maximization is, perhaps, Max Bill’s main lesson.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Ren and colleagues (2006) found that saccades to visual targets became less accurate when somatosensory information about hand location was added, suggesting that saccades rely mainly on vision. We conducted two kinematic experiments to examine whether or not reaching movements would also show such strong reliance on vision. In Experiment 1, subjects used their dominant right hand to perform reaches, with or without a delay, to an external visual target or to their own left fingertip positioned either by the experimenter or by the participant. Unlike saccades, reaches became more accurate and precise when proprioceptive information was available. In Experiment 2, subjects reached toward external or bodily targets with differing amounts of visual information. Proprioception improved performance only when vision was limited. Our results indicate that reaching movements, unlike saccades, are improved rather than impaired by the addition of somatosensory information.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Prehension in an act of coordinated reaching and grasping. The reaching component is concerned with bringing the hand to object to be grasped (transport phase); the grasping component refers to the shaping of the hand according to the object features (grasping phase) (Jeannerod, 1981). Reaching and grasping involve different muscles, proximal and distal muscles respectively, and are controlled by different parietofrontal circuit (Jeannerod et al., 1995): a medial circuit, involving area of superior parietal lobule and dorsal premotor area 6 (PMd) (dorsomedial visual stream), is mainly concerned with reaching; a lateral circuit, involving the inferior parietal lobule and ventral premotor area 6 (PMv) (dorsolateral visual stream), with grasping. Area V6A is located in the caudalmost part of the superior parietal lobule, so it belongs to the dorsomedial visual stream; it contains neurons sensitive to visual stimuli (Galletti et al. 1993, 1996, 1999) as well as cells sensitive to the direction of gaze (Galletti et al. 1995) and cells showing saccade-related activity (Nakamura et al. 1999; Kutz et al. 2003). Area V6A contains also arm-reaching neurons likely involved in the control of the direction of the arm during movements towards objects in the peripersonal space (Galletti et al. 1997; Fattori et al. 2001). The present results confirm this finding and demonstrate that during the reach-to-grasp the V6A neurons are also modulated by the orientation of the wrist. Experiments were approved by the Bioethical Committee of the University of Bologna and were performed in accordance with National laws on care and use of laboratory animals and with the European Communities Council Directive of 24th November 1986 (86/609/EEC), recently revised by the Council of Europe guidelines (Appendix A of Convention ETS 123). Experiments were performed in two awake Macaca fascicularis. Each monkey was trained to sit in a primate chair with the head restrained to perform reaching and grasping arm movements in complete darkness while gazing a small fixation point. The object to be grasped was a handle that could have different orientation. We recorded neural activity from 163 neurons of the anterior parietal sulcus; 116/163 (71%) neurons were modulated by the reach-to-grasp task during the execution of the forward movements toward the target (epoch MOV), 111/163 (68%) during the pulling of the handle (epoch HOLD) and 102/163 during the execution of backward movements (epoch M2) (t_test, p ≤ 0.05). About the 45% of the tested cells turned out to be sensitive to the orientation of the handle (one way ANOVA, p ≤ 0.05). To study how the distal components of the movement, such as the hand preshaping during the reaching of the handle, could influence the neuronal discharge, we compared the neuronal activity during the reaching movements towards the same spatial location in reach-to-point and reach-to-grasp tasks. Both tasks required proximal arm movements; only the reach-to-grasp task required distal movements to orient the wrist and to shape the hand to grasp the handle. The 56% of V6A cells showed significant differences in the neural discharge (one way ANOVA, p ≤ 0.05) between the reach-to-point and the reach-to-grasp tasks during MOV, 54% during HOLD and 52% during M2. These data show that reaching and grasping are processed by the same population of neurons, providing evidence that the coordination of reaching and grasping takes place much earlier than previously thought, i.e., in the parieto-occipital cortex. The data here reported are in agreement with results of lesions to the medial posterior parietal cortex in both monkeys and humans, and with recent imaging data in humans, all of them indicating a functional coupling in the control of reaching and grasping by the medial parietofrontal circuit.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The treatment of the Cerebral Palsy (CP) is considered as the “core problem” for the whole field of the pediatric rehabilitation. The reason why this pathology has such a primary role, can be ascribed to two main aspects. First of all CP is the form of disability most frequent in childhood (one new case per 500 birth alive, (1)), secondarily the functional recovery of the “spastic” child is, historically, the clinical field in which the majority of the therapeutic methods and techniques (physiotherapy, orthotic, pharmacologic, orthopedic-surgical, neurosurgical) were first applied and tested. The currently accepted definition of CP – Group of disorders of the development of movement and posture causing activity limitation (2) – is the result of a recent update by the World Health Organization to the language of the International Classification of Functioning Disability and Health, from the original proposal of Ingram – A persistent but not unchangeable disorder of posture and movement – dated 1955 (3). This definition considers CP as a permanent ailment, i.e. a “fixed” condition, that however can be modified both functionally and structurally by means of child spontaneous evolution and treatments carried out during childhood. The lesion that causes the palsy, happens in a structurally immature brain in the pre-, peri- or post-birth period (but only during the firsts months of life). The most frequent causes of CP are: prematurity, insufficient cerebral perfusion, arterial haemorrhage, venous infarction, hypoxia caused by various origin (for example from the ingestion of amniotic liquid), malnutrition, infection and maternal or fetal poisoning. In addition to these causes, traumas and malformations have to be included. The lesion, whether focused or spread over the nervous system, impairs the whole functioning of the Central Nervous System (CNS). As a consequence, they affect the construction of the adaptive functions (4), first of all posture control, locomotion and manipulation. The palsy itself does not vary over time, however it assumes an unavoidable “evolutionary” feature when during growth the child is requested to meet new and different needs through the construction of new and different functions. It is essential to consider that clinically CP is not only a direct expression of structural impairment, that is of etiology, pathogenesis and lesion timing, but it is mainly the manifestation of the path followed by the CNS to “re”-construct the adaptive functions “despite” the presence of the damage. “Palsy” is “the form of the function that is implemented by an individual whose CNS has been damaged in order to satisfy the demands coming from the environment” (4). Therefore it is only possible to establish general relations between lesion site, nature and size, and palsy and recovery processes. It is quite common to observe that children with very similar neuroimaging can have very different clinical manifestations of CP and, on the other hand, children with very similar motor behaviors can have completely different lesion histories. A very clear example of this is represented by hemiplegic forms, which show bilateral hemispheric lesions in a high percentage of cases. The first section of this thesis is aimed at guiding the interpretation of CP. First of all the issue of the detection of the palsy is treated from historical viewpoint. Consequently, an extended analysis of the current definition of CP, as internationally accepted, is provided. The definition is then outlined in terms of a space dimension and then of a time dimension, hence it is highlighted where this definition is unacceptably lacking. The last part of the first section further stresses the importance of shifting from the traditional concept of CP as a palsy of development (defect analysis) towards the notion of development of palsy, i.e., as the product of the relationship that the individual however tries to dynamically build with the surrounding environment (resource semeiotics) starting and growing from a different availability of resources, needs, dreams, rights and duties (4). In the scientific and clinic community no common classification system of CP has so far been universally accepted. Besides, no standard operative method or technique have been acknowledged to effectively assess the different disabilities and impairments exhibited by children with CP. CP is still “an artificial concept, comprising several causes and clinical syndromes that have been grouped together for a convenience of management” (5). The lack of standard and common protocols able to effectively diagnose the palsy, and as a consequence to establish specific treatments and prognosis, is mainly because of the difficulty to elevate this field to a level based on scientific evidence. A solution aimed at overcoming the current incomplete treatment of CP children is represented by the clinical systematic adoption of objective tools able to measure motor defects and movement impairments. A widespread application of reliable instruments and techniques able to objectively evaluate both the form of the palsy (diagnosis) and the efficacy of the treatments provided (prognosis), constitutes a valuable method able to validate care protocols, establish the efficacy of classification systems and assess the validity of definitions. Since the ‘80s, instruments specifically oriented to the analysis of the human movement have been advantageously designed and applied in the context of CP with the aim of measuring motor deficits and, especially, gait deviations. The gait analysis (GA) technique has been increasingly used over the years to assess, analyze, classify, and support the process of clinical decisions making, allowing for a complete investigation of gait with an increased temporal and spatial resolution. GA has provided a basis for improving the outcome of surgical and nonsurgical treatments and for introducing a new modus operandi in the identification of defects and functional adaptations to the musculoskeletal disorders. Historically, the first laboratories set up for gait analysis developed their own protocol (set of procedures for data collection and for data reduction) independently, according to performances of the technologies available at that time. In particular, the stereophotogrammetric systems mainly based on optoelectronic technology, soon became a gold-standard for motion analysis. They have been successfully applied especially for scientific purposes. Nowadays the optoelectronic systems have significantly improved their performances in term of spatial and temporal resolution, however many laboratories continue to use the protocols designed on the technology available in the ‘70s and now out-of-date. Furthermore, these protocols are not coherent both for the biomechanical models and for the adopted collection procedures. In spite of these differences, GA data are shared, exchanged and interpreted irrespectively to the adopted protocol without a full awareness to what extent these protocols are compatible and comparable with each other. Following the extraordinary advances in computer science and electronics, new systems for GA no longer based on optoelectronic technology, are now becoming available. They are the Inertial and Magnetic Measurement Systems (IMMSs), based on miniature MEMS (Microelectromechanical systems) inertial sensor technology. These systems are cost effective, wearable and fully portable motion analysis systems, these features gives IMMSs the potential to be used both outside specialized laboratories and to consecutive collect series of tens of gait cycles. The recognition and selection of the most representative gait cycle is then easier and more reliable especially in CP children, considering their relevant gait cycle variability. The second section of this thesis is focused on GA. In particular, it is firstly aimed at examining the differences among five most representative GA protocols in order to assess the state of the art with respect to the inter-protocol variability. The design of a new protocol is then proposed and presented with the aim of achieving gait analysis on CP children by means of IMMS. The protocol, named ‘Outwalk’, contains original and innovative solutions oriented at obtaining joint kinematic with calibration procedures extremely comfortable for the patients. The results of a first in-vivo validation of Outwalk on healthy subjects are then provided. In particular, this study was carried out by comparing Outwalk used in combination with an IMMS with respect to a reference protocol and an optoelectronic system. In order to set a more accurate and precise comparison of the systems and the protocols, ad hoc methods were designed and an original formulation of the statistical parameter coefficient of multiple correlation was developed and effectively applied. On the basis of the experimental design proposed for the validation on healthy subjects, a first assessment of Outwalk, together with an IMMS, was also carried out on CP children. The third section of this thesis is dedicated to the treatment of walking in CP children. Commonly prescribed treatments in addressing gait abnormalities in CP children include physical therapy, surgery (orthopedic and rhizotomy), and orthoses. The orthotic approach is conservative, being reversible, and widespread in many therapeutic regimes. Orthoses are used to improve the gait of children with CP, by preventing deformities, controlling joint position, and offering an effective lever for the ankle joint. Orthoses are prescribed for the additional aims of increasing walking speed, improving stability, preventing stumbling, and decreasing muscular fatigue. The ankle-foot orthosis (AFO), with a rigid ankle, are primarily designed to prevent equinus and other foot deformities with a positive effect also on more proximal joints. However, AFOs prevent the natural excursion of the tibio-tarsic joint during the second rocker, hence hampering the natural leaning progression of the whole body under the effect of the inertia (6). A new modular (submalleolar) astragalus-calcanear orthosis, named OMAC, has recently been proposed with the intention of substituting the prescription of AFOs in those CP children exhibiting a flat and valgus-pronated foot. The aim of this section is thus to present the mechanical and technical features of the OMAC by means of an accurate description of the device. In particular, the integral document of the deposited Italian patent, is provided. A preliminary validation of OMAC with respect to AFO is also reported as resulted from an experimental campaign on diplegic CP children, during a three month period, aimed at quantitatively assessing the benefit provided by the two orthoses on walking and at qualitatively evaluating the changes in the quality of life and motor abilities. As already stated, CP is universally considered as a persistent but not unchangeable disorder of posture and movement. Conversely to this definition, some clinicians (4) have recently pointed out that movement disorders may be primarily caused by the presence of perceptive disorders, where perception is not merely the acquisition of sensory information, but an active process aimed at guiding the execution of movements through the integration of sensory information properly representing the state of one’s body and of the environment. Children with perceptive impairments show an overall fear of moving and the onset of strongly unnatural walking schemes directly caused by the presence of perceptive system disorders. The fourth section of the thesis thus deals with accurately defining the perceptive impairment exhibited by diplegic CP children. A detailed description of the clinical signs revealing the presence of the perceptive impairment, and a classification scheme of the clinical aspects of perceptual disorders is provided. In the end, a functional reaching test is proposed as an instrumental test able to disclosure the perceptive impairment. References 1. Prevalence and characteristics of children with cerebral palsy in Europe. Dev Med Child Neurol. 2002 Set;44(9):633-640. 2. Bax M, Goldstein M, Rosenbaum P, Leviton A, Paneth N, Dan B, et al. Proposed definition and classification of cerebral palsy, April 2005. Dev Med Child Neurol. 2005 Ago;47(8):571-576. 3. Ingram TT. A study of cerebral palsy in the childhood population of Edinburgh. Arch. Dis. Child. 1955 Apr;30(150):85-98. 4. Ferrari A, Cioni G. The spastic forms of cerebral palsy : a guide to the assessment of adaptive functions. Milan: Springer; 2009. 5. Olney SJ, Wright MJ. Cerebral Palsy. Campbell S et al. Physical Therapy for Children. 2nd Ed. Philadelphia: Saunders. 2000;:533-570. 6. Desloovere K, Molenaers G, Van Gestel L, Huenaerts C, Van Campenhout A, Callewaert B, et al. How can push-off be preserved during use of an ankle foot orthosis in children with hemiplegia? A prospective controlled study. Gait Posture. 2006 Ott;24(2):142-151.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Reaching and grasping an object is an action that can be performed in light, under visual guidance, as well as in darkness, under proprioceptive control only. Area V6A is a visuomotor area involved in the control of reaching movements. V6A, besides neurons activated by the execution of reaching movements, shows passive somatosensory and visual responses. This suggests fro V6A a multimodal capability of integrating sensory and motor-related information, We wanted to know whether this integration occurrs in reaching movements and in the present study we tested whether the visual feedback influenced the reaching activity of V6A neurons. In order to better address this question, we wanted to interpret the neural data in the light of the kinematic of reaching performance. We used an experimental paradigm that could examine V6A responses in two different visual backgrounds, light and dark. In these conditions, the monkey performed an istructed-delay reaching task moving the hand towards different target positions located in the peripersonal space. During the execution of reaching task, the visual feedback is processed in a variety of patterns of modulation, sometimes not expected. In fact, having already demonstrated in V6A reach-related discharges in absence of visual feedback, we expected two types of neural modulation: 1) the addition of light in the environment enhanced reach-related discharges recorded in the dark; 2) the light left the neural response unmodified. Unexpectedly, the results show a complex pattern of modulation that argues against a simple additive interaction between visual and motor-related signals.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Progettazione delle procedure necessarie alla realizzazione di piattaforme off-shore, grandi e complesse strutture intelaiate di pilastri, diagonali, travi primarie e travi secondarie, progettate per insediarsi in ambiente marino ed idonee ad ospitare impianti per l'estrazione di idrocarburi. Durante la fase di progettazione si procede con l'ideare la struttura della piattaforma fino a definire le caratteristiche di ogni componente: tale fase ha come esito la redazione dei project drawings (disegni di progetto). La fase di realizzazione è quella che interessa propriamente il lavoro svolto: a seguito della progettazione infatti emergono nuove problematiche a livello applicativo e costruttivo che necessitano di essere studiate e risolte preventivamente alla costruzione fisica dell'opera. In particolar modo è necessario definire quali parti della struttura possono essere acquistate e quali invece devono essere realizzate su misura. Definite le modalità costruttive, viene effettuato lo studio riguardante la movimentazione dei vari piani della piattaforma, movement, e successivamente le problematiche relative al sollevamento degli stessi, lifting. Le due procedure necessitano di raffinate valutazioni euristiche ed analitiche per garantire che la struttura non collassi.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

One of the quickest plant movements ever known is made by the ´explosive´ style in Marantaceae in the service of secondary pollen presentation – herewith showing a striking apomorphy to the sister Cannaceae that might be of high evolutionary consequence. Though known already since the beginning of the 19th century the underlying mechanism of the movement has hitherto not been clarified. The present study reports about the biomechanics of the style-staminode complex and the hydraulic principles of the movement. For the first time it is shown by experiment that in Maranta noctiflora through longitudinal growth of the maturing style in the ´straitjacket´ of the hooded staminode both the hold of the style prior to its release and its tensioning for the movement are brought about. The longer the style grows in relation to the enclosing hooded staminode the more does its capacity for curling up for pollen transfer increase. Hereby I distinguish between the ´basic tension´ that a growing style builds up anyway, even when the hooded staminode is removed beforehand, and the ´induced tension´ which comes about only under the pressure of a ´too short´ hooded staminode and which enables the movement. The results of these investigations are discussed in view of previous interpretations ranging from possible biomechanical to electrophysiological mechanisms. To understand furthermore by which means the style gives way to the strong bending movement without suffering outwardly visible damage I examined its anatomical structure in several genera for its mechanical and hydraulic properties and for the determination of the entire curvature after release. The actual bending part contains tubulate cells whose walls are extraordinarily porous and large longitudinal intercellular spaces. SEM indicates the starting points of cell-wall loosening in primary walls and lysis of middle lamellae - probably through an intense pectinase activity in the maturing style. Fluorescence pictures of macerated and living style-tissue confirm cell-wall perforations that do apparently connect neighbouring cells, which leads to an extremely permeable parenchyma. The ´water-body´ can be shifted from central to dorsal cell layers to support the bending. The geometrical form of the curvature is determined by the vascular bundles. I conclude that the style in Marantaceae contains no ´antagonistic´ motile tissues as in Mimosa or Dionaea. Instead, through self-maceration it develops to a ´hydraulic tissue´ which carries out an irreversible movement through a sudden reshaping. To ascertain the evolutionary consequence of this apomorphic pollination mechanism the diversity and systematic value of hooded staminodes are examined. For this hooded staminodes of 24 genera are sorted according to a minimalistic selection of shape characters and eight morphological types are abstracted from the resulting groups. These types are mapped onto an already available maximally parsimonious tree comprising five major clades. An amazing correspondence is found between the morphological types and the clades; several sister-relationships are confirmed and in cases of uncertain position possible evolutionary pathways, such as convergence, dispersal or re-migration, are discussed, as well as the great evolutionary tendencies for the entire family in which – at least as regards the shape of hooded staminodes – there is obviously a tendency from complicated to strongly simplified forms. It suggests itself that such simplifying derivations may very likely have taken place as adaptations to pollinating animals about which at present too little is known. The value of morphological characters in relation to modern phylogenetic analysis is discussed and conditions for the selection of morphological characters valuable for a systematic grouping are proposed. Altogether, in view of the evolutionary success of Marantaceae compared with Cannaceae the movement mechanism of the style-staminode complex can safely be considered a key innovation within the order Zingiberales.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The evaluation of the farmers’ communities’ approach to the Slow Food vision, their perception of the Slow Food role in supporting their activity and their appreciation and expectations from participating in the event of Mother Earth were studied. The Unified Theory of Acceptance and Use of Technology (UTAUT) model was adopted in an agro-food sector context. A survey was conducted, 120 questionnaires from farmers attending the Mother Earth in Turin in 2010 were collected. The descriptive statistical analysis showed that both Slow Food membership and participation to Mother Earth Meeting were much appreciated for the support provided to their business and the contribution to a more sustainable and fair development. A positive social, environmental and psychological impact on farmers also resulted. Results showed also an interesting perspective on the possible universality of the Slow Food and Mother Earth values. Farmers declared that Slow Food is supporting them by preserving the biodiversity and orienting them to the use of local resources and reducing the chemical inputs. Many farmers mentioned the language/culture and administration/bureaucratic issues as an obstacle to be a member in the movement and to participate to the event. Participation to Mother Earth gives an opportunity to exchange information with other farmers’ communities and to participate to seminars and debates, helpful for their business development. The absolute majority of positive answers associated to the farmers’ willingness to relate to Slow Food and participate to the next Mother Earth editions negatively influenced the UTAUT model results. A factor analysis showed that the variables associated to the UTAUT model constructs Performance Expectancy and Effort Expectancy were consistent, able to explain the construct variability, and their measurement reliable. Their inclusion in a simplest Technology Acceptance Model could be considered in future researches.