632 resultados para RIGIDITY


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Replacement of the traditional coil spring with one of more fibre-reinforced plastic sulcated springs is a future possibility. Spring designers of metallic coil springs have design formulae readily available, and software packages specific to coil spring design exist. However, the sulcated spring is at the prototype stage of development, so literature on these springs is very sparse. The thesis contains information on the market for sulcated springs, and their advantages and disadvantages. Literature on other types of fibre reinforced plastic springs has also been reviewed. Design software has been developed for the sulcated spring along similar lines to coil spring design software. In order to develop the software, a theoretical model had to be developed which formed the mathematical basis for the software. The theoretical model is based on a choice of four methods for calculating the flexural rigidity; beam theory, plate theory, and lamination theory assuming isotropic and orthoropic material properties. Experimental results for strain and spring stiffness have been compared with the theoretical model, and were in good agreement. Included in the design software are the results of experimental work on fatigue, and design limiting factors to prevent or warn against impractical designs. Finite element analysis has been used to verify the theoretical model developed, and to find the better approximation to the experimental results. Applications and types of assemblies for the sulcated spring were discussed. Sulcated spring designs for the automotive applications of a suspension, clutch and engine valve spring were found using the design computer software. These sulcated spring designs were within or close to the space of the existing coil spring and yield the same performance. Finally the commercial feasibility of manufacturing the sulcated spring was assessed and compared with the coil spring, to evaluate the plausibility of the sulcated spring replacing the coil spring eventually.

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Using a novel modeling approach, and cross-country firm level data for the textiles industry, we examine the impact of institutional quality on firm performance. Our methodology allows us to estimate the marginal impact of institutional quality on productivity of each firm. Our results bring into question conventional wisdom about the desirable characteristics of market institutions, which is based on empirical evidence about the impact of institutional quality on the average firm. We demonstrate, for example, that once both the direct impact of a change in institutional quality on total factor productivity and the indirect impact through changes in efficiency of use of factor inputs are taken into account, an increase in labor market rigidity may have a positive impact on firm output, at least for some firms. We also demonstrate that there are significant intra-country variations in the marginal impact of institutional quality, such that the characteristics of “winners” and “losers” will have to be taken into account before policy is introduced to change institutional quality in any direction.

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Dementia with Lewy bodies ('Lewy body dementia' or 'diffuse Lewy body disease') (DLB) is the second most common form of dementia to affect elderly people, after Alzheimer's disease. A combination of the clinical symptoms of Alzheimer's disease and Parkinson's disease is present in DLB and the disorder is classified as a 'parkinsonian syndrome', a group of diseases which also includes Parkinson's disease, progressive supranuclear palsy, corticobasal degeneration and multiple system atrophy. Characteristics of DLB are fluctuating cognitive ability with pronounced variations in attention and alertness, recurrent visual hallucinations and spontaneous motor features, including akinesia, rigidity and tremor. In addition, DLB patients may exhibit visual signs and symptoms, including defects in eye movement, pupillary function and complex visual functions. Visual symptoms may aid the differential diagnoses of parkinsonian syndromes. Hence, the presence of visual hallucinations supports a diagnosis of Parkinson's disease or DLB rather than progressive supranuclear palsy. DLB and Parkinson's disease may exhibit similar impairments on a variety of saccadic and visual perception tasks (visual discrimination, space-motion and object-form recognition). Nevertheless, deficits in orientation, trail-making and reading the names of colours are often significantly greater in DLB than in Parkinson's disease. As primary eye-care practitioners, optometrists should be able to work with patients with DLB and their carers to manage their visual welfare.

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This paper addresses the problem of obtaining 3d detailed reconstructions of human faces in real-time and with inexpensive hardware. We present an algorithm based on a monocular multi-spectral photometric-stereo setup. This system is known to capture high-detailed deforming 3d surfaces at high frame rates and without having to use any expensive hardware or synchronized light stage. However, the main challenge of such a setup is the calibration stage, which depends on the lights setup and how they interact with the specific material being captured, in this case, human faces. For this purpose we develop a self-calibration technique where the person being captured is asked to perform a rigid motion in front of the camera, maintaining a neutral expression. Rigidity constrains are then used to compute the head's motion with a structure-from-motion algorithm. Once the motion is obtained, a multi-view stereo algorithm reconstructs a coarse 3d model of the face. This coarse model is then used to estimate the lighting parameters with a stratified approach: In the first step we use a RANSAC search to identify purely diffuse points on the face and to simultaneously estimate this diffuse reflectance model. In the second step we apply non-linear optimization to fit a non-Lambertian reflectance model to the outliers of the previous step. The calibration procedure is validated with synthetic and real data.

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Differential clinical diagnosis of the parkinsonian syndromes, viz., Parkinson’s disease (PD), progressive supranuclear palsy (PSP), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA) can be difficult. Eye movement problems, however, are a chronic complication of many of these disorders and may be a useful aid to diagnosis. Hence, the presence in PSP of vertical supranuclear gaze palsy, fixation instability, lid retraction, blepharospasm, and apraxia of eyelid opening and closing is useful in separating PD from PSP. Moreover, atypical features of PSP include slowing of upward saccades, moderate slowing of downward saccades, the presence of a full range of voluntary vertical eye movements, a curved trajectory of oblique saccades, and absence of square-wave jerks. Downgaze palsy is probably the most useful diagnostic clinical symptom of PSP. By contrast, DLB patients are specifically impaired in both reflexive and saccadic execution and in the performance of more complex saccadic eye movement tasks. Problems in convergence in DLB are also followed by akinesia and rigidity. Abnormal ocular fixation may occur in a significant proportion of MSA patients along with excessive square-wave jerks, a mild supranuclear gaze palsy, a gaze-evoked nystagmus, a positioning down-beat nystagmus, mild-moderate saccadic hypometria, impaired smooth pursuit movements, and reduced vestibulo-ocular reflex (VOR) suppression. There may be considerable overlap between the eye movement problems characteristic of the various parkinsonian disorders, but taken together with other signs and symptoms, can be a useful aid in differential diagnosis, especially in the separation of PD and PSP.

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Tuberculosis (TB), an infection caused by human pathogen Mycobacterium tuberculosis, continues to kill millions each year and is as prevalent as it was in the pre-antimicrobial era. With the emergence of continuously-evolving multi-drug resistant strains (MDR) and the implications of the HIV epidemic, it is crucial that new drugs with better efficacy and affordable cost are developed to treat TB. With this in mind, the first part of this thesis discusses the synthesis of libraries of derivatives of pyridine carboxamidrazones, along with cyclised (1,2,4-triazole and 1,2,4-oxadiazole) and fluorinated analogues. Microbiological screening against M. tuberculosis was carried out at the TAACF, NIAID and IDRI (USA). This confirmed the earlier findings that 2-pyridyl-substituted carboxamidrazones were more active than the 4-pyridyl-substituted carboxamidrazones. Another important observation was that upon cyclisation of these carboxamidrazones, a small number of the triazoles retained their activity while in most of the remaining compounds the activity was diminished. This might be attributed to the significant increase in logP value caused by cyclisation of these linear carboxamidrazones, resulting in high lipophilicity and decreased permeability. Another reason might be that the rigidity conferred upon the compound due to cyclisation, results in failure of the compound to fit into the active site of the putative target enzyme. In order to investigate the potential change to the compounds’ metabolism in the organism and/or host, the most active compounds were selected and a fluorine atom was introduced in the pyridine ring. The microbiological results shows a drastic improvement in the activity of the fluorinated carboxamidrazone amides as compared to their non fluorinated counterpart. This improvement in the activity could possibly be the result of the increased cell permeability caused by the fluorine. In a subsidiary strand, a selection of long-chain , -unsaturated carboxylic esters, -keto, -hydroxy carboxylic esters and -keto, -hydroxy carboxylic esters, structurally similar to mycolic acids, were synthesised. The microbiological data revealed that one of the open chain compound was active against the Mycobacterium tuberculosis H37Rv strain and some resistant isolates. The possible compound activity could be its potential to disrupt mycobacterial cell wall synthesis by interfering with the FAS-II pathway.

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Corticobasal degeneration is a rare, progressive neurodegenerative disorder which significantly impairs movement. The most common initial symptom is asymmetric limb clumsiness with or without accompanying rigidity or tremor. Subsequently, the disease progresses to affect gait and there is a slow progression to influence ipsilateral arms and legs. Apraxia and dementia are the most common cortical signs. Clinical diagnosis of the disorder is difficult as the symptoms resemble those of related neurodegenerative disorders. Histopathologically, there is widespread neuronal and glial pathology including tau-immunoreactive neuronal cytoplasmic inclusions, neuropil threads, oligodendroglial inclusions, astrocytic plaques, together with abnormally enlarged ‘ballooned’ neurons. Corticobasal degeneration has affinities both with the parkinsonian syndromes including Parkinson’s disease, progressive supranuclear palsy, and multiple system atrophy and with the fronto-temporal dementias. Treatment of corticobasal degeneration involves managing and reducing the effect of symptoms.

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Dementia with Lewy bodies (‘Lewy body dementia' or ‘diffuse Lewy body disease') (DLB) is the second commonest form of dementia after Alzheimer’s disease (AD). Characteristic of DLB are: (1) fluctuating cognitive ability with variations in attention and alertness, (2) recurrent visual hallucinations, and (3) motor features including akinesia, rigidity, and tremor. Various brain regions are affected in DLD including cortical and limbic regions. Histopathologically, alpha-synuclein-immunoreactive Lewy bodies (LB) are observed in the substantia nigra and in the cerebral cortex. DLB has affinities both with the parkinsonian syndromes including Parkinson’s disease (PD), progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), and multiple system atrophy (MSA), and with AD, which can make differential diagnosis difficult. The presence of visual hallucinations may aid differential diagnosis of the parkinsononian syndromes and occipital hypometabolism may be a useful potential method of distinguishing DLB from AD. Treatment of CBD involves managing and reducing the effect of symptoms.

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The primary aim of this thesis was to investigate the in vivo ocular morphological and contractile changes occurring within the accommodative apparatus prior to the onset of presbyopia, with particular reference to ciliary muscle changes with age and the origin of a myopic shift in refraction during incipient presbyopia. Commissioned semi-automated software proved capable of extracting accurate and repeatable measurements from crystalline lens and ciliary muscle Anterior Segment Optical Coherence Tomography (AS-OCT) images and reduced the subjectivity of AS-OCT image analysis. AS-OCT was utilised to document longitudinal changes in ciliary muscle morphology within an incipient presbyopic population (n=51). A significant antero-inwards shift of ciliary muscle mass was observed after 2.5 years. Furthermore, in a subgroup study (n=20), an accommodative antero-inwards movement of ciliary muscle mass was evident. After 2.5 years, the centripetal response of the ciliary muscle significantly attenuated during accommodation, whereas the antero-posterior mobility of the ciliary muscle remained invariant. Additionally, longitudinal measurement of ocular biometry revealed a significant increase in crystalline lens thickness and a corresponding decrease in anterior chamber depth after 2.5 years (n=51). Lenticular changes appear to be determinant of changes in refraction during incipient presbyopia. During accommodation, a significant increase in crystalline lens thickness and axial length was observed, whereas anterior chamber depth decreased (n=20). The change in ocular biometry per dioptre of accommodation exerted remained invariant after 2.5 years. Cross-sectional ocular biometric data were collected to quantify accommodative axial length changes from early adulthood to advanced presbyopia (n=72). Accommodative axial length elongation significantly attenuated during presbyopia, which was consistent with a significant increase in ocular rigidity during presbyopia. The studies presented in this thesis support the Helmholtz theory of accommodation and despite the reduction in centripetal ciliary muscle contractile response with age, primarily implicate lenticular changes in the development of presbyopia.

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The best results in the application of computer science systems to automatic translation are obtained in word processing when texts pertain to specific thematic areas, with structures well defined and a concise and limited lexicon. In this article we present a plan of systematic work for the analysis and generation of language applied to the field of pharmaceutical leaflet, a type of document characterized by format rigidity and precision in the use of lexicon. We propose a solution based in the use of one interlingua as language pivot between source and target languages; we are considering Spanish and Arab languages in this case of application.

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Background: Remote, non-invasive and objective tests that can be used to support expert diagnosis for Parkinson's disease (PD) are lacking. Methods: Participants underwent baseline in-clinic assessments, including the Unified Parkinson's Disease Rating Scale (UPDRS), and were provided smartphones with an Android operating system that contained a smartphone application that assessed voice, posture, gait, finger tapping, and response time. Participants then took the smart phones home to perform the five tasks four times a day for a month. Once a week participants had a remote (telemedicine) visit with a Parkinson disease specialist in which a modified (excluding assessments of rigidity and balance) UPDRS performed. Using statistical analyses of the five tasks recorded using the smartphone from 10 individuals with PD and 10 controls, we sought to: (1) discriminate whether the participant had PD and (2) predict the modified motor portion of the UPDRS. Results: Twenty participants performed an average of 2.7 tests per day (68.9% adherence) for the study duration (average of 34.4 days) in a home and community setting. The analyses of the five tasks differed between those with Parkinson disease and those without. In discriminating participants with PD from controls, the mean sensitivity was 96.2% (SD 2%) and mean specificity was 96.9% (SD 1.9%). The mean error in predicting the modified motor component of the UPDRS (range 11-34) was 1.26 UPDRS points (SD 0.16). Conclusion: Measuring PD symptoms via a smartphone is feasible and has potential value as a diagnostic support tool.

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Liposomes not only offer the ability to enhance drug delivery, but can effectively act as vaccine delivery systems and adjuvants. Their flexibility in size, charge, bilayer rigidity and composition allow for targeted antigen delivery via a range of administration routes. In the development of liposomal adjuvants, the type of immune response promoted has been linked to their physico-chemical characteristics, with the size and charge of the liposomal particles impacting on liposome biodistribution, exposure in the lymph nodes and recruitment of the innate immune system. The addition of immunostimulatory agents can further potentiate their immunogenic properties. Here, we outline the attributes that should be considered in the design and manufacture of liposomal adjuvants for the delivery of sub-unit and nucleic acid based vaccines.

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Although people and events that disconfirm observers' expectancies can increase their creativity, sometimes such social schema violations increase observers' rigidity of thought and undermine creative cognition. Here we examined whether individual differences in the extent to which people prefer structure and predictability determine whether social schema violations facilitate or hamper creativity. Participants in Study 1 formed impressions of a schema-inconsistent female mechanic (vs. a schema-consistent male mechanic). Following schema-inconsistent rather than -consistent information, participants low (high) in need for structure showed better (impeded) creative performance. Participants in Study 2 memorized a series of images in which individuals were placed on a schema-inconsistent (vs. consistent) background (e.g., an Eskimo on the desert vs. on a snowy landscape). Following schema-inconsistent imagery, participants low (high) in need for structure increased (decreased) divergent thinking. © 2014 by the Society for Personality and Social Psychology, Inc.

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The purpose of this descriptive study was to evaluate the banking and insurance technology curriculum at ten junior colleges in Taiwan. The study focused on curriculum, curriculum materials, instruction, support services, student achievement and job performance. Data was collected from a diverse sample of faculty, students, alumni, and employers. ^ Questionnaires on the evaluation of curriculum at technical junior colleges were developed for use in this specific case. Data were collected from the sample described above and analyzed utilizing ANOVA, T-Tests and crosstabulations. Findings are presented which indicate that there is room for improvement in terms of meeting individual students' needs. ^ Using Stufflebeam's CIPP model for curriculum evaluation it was determined that the curriculum was adequate in terms of the knowledge and skills imparted to students. However, students were dissatisfied with the rigidity of the curriculum and the lack of opportunity to satisfy the individual needs of students. Employers were satisfied with both the academic preparation of students and their on the job performance. ^ In sum, the curriculum of the two-year banking and insurance technology programs of junior college in Taiwan was shown to have served adequately preparing a work force to enter businesses. It is now time to look toward the future and adapt the curriculum and instruction for the future needs of the ever evolving high-tech society. ^

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Natural and man-made disasters have gained attention at all levels of policy-making in recent years. Emergency management tasks are inherently complex and unpredictable, and often require coordination among multiple organizations across different levels and locations. Effectively managing various knowledge areas and the organizations involved has become a critical emergency management success factor. However, there is a general lack of understanding about how to describe and assess the complex nature of emergency management tasks and how knowledge integration can help managers improve emergency management task performance. ^ The purpose of this exploratory research was first, to understand how emergency management operations are impacted by tasks that are complex and inter-organizational and second, to investigate how knowledge integration as a particular knowledge management strategy can improve the efficiency and effectiveness of the emergency tasks. Three types of specific knowledge were considered: context-specific, technology-specific, and context-and-technology-specific. ^ The research setting was the Miami-Dade Emergency Operations Center (EOC) and the study was based on the survey responses from the participants in past EOC activations related to their emergency tasks and knowledge areas. The data included task attributes related to complexity, knowledge area, knowledge integration, specificity of knowledge, and task performance. The data was analyzed using multiple linear regressions and path analyses, to (1) examine the relationships between task complexity, knowledge integration, and performance, (2) the moderating effects of each type of specific knowledge on the relationship between task complexity and performance, and (3) the mediating role of knowledge integration. ^ As per theory-based propositions, the results indicated that overall component complexity and interactive complexity tend to have a negative effect on task performance. But surprisingly, procedural rigidity tended to have a positive effect on performance in emergency management tasks. Also as per our expectation, knowledge integration had a positive relationship with task performance. Interestingly, the moderating effects of each type of specific knowledge on the relationship between task complexity and performance were varied and the extent of mediation of knowledge integration depended on the dimension of task complexity. ^