• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1036
  • 402
  • 166
  • 106
  • 95
  • 83
  • 46
  • 37
  • 37
  • 37
  • 37
  • 37
  • 37
  • 22
  • 20
  • Tagged with
  • 2472
  • 664
  • 311
  • 285
  • 246
  • 185
  • 182
  • 173
  • 168
  • 161
  • 157
  • 155
  • 141
  • 140
  • 128
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Relationships between symptom interference scores, reduced dietary intake, weight loss, and reduced functional capacity

Schmidt, Karmen 06 1900 (has links)
Using an existing data set comprised of 368 individuals newly diagnosed with cancers of the head and neck, we investigated the predictive validity of the Head and Neck Patient Symptom Checklist (HNSC) by comparing scores on the HNSC to scores on the Patient-Generated Symptom Global Assessment (PG-SGA), and by examining the ability of HNSC scores and four demographic variables to predict dietary intake, weight loss, and functional capacity. HNSC sensitivity (0.79 0.98), specificity (0.99 1.00), positive predictive value (92% 100%), and negative predictive value (94% - 100%) were excellent. Pain, loss of appetite and difficulty swallowing predicted 82% of reduced dietary intake. Advanced tumor stage, loss of appetite and difficulty swallowing predicted 79% of weight loss. Loss of appetite, difficulty swallowing, feeling full and lack of energy predicted 78% of reduced functional capacity. The HNSC appears to be valid and could aid with early symptom identification, intervention and improved outcomes.
182

ETUDE DE LA DYSMORPHOSE CRANIOFACIALE CHEZ LE RAT DUMBO

Katerji, Suhair 22 June 2009 (has links)
RESUME Le rat Dumbo présente un aspect malformatif évoquant certains syndromes crânio-faciaux humains. La compréhension du phénotype Dumbo pourrait expliquer les événements cellulaires et moléculaires à l’origine de ces syndromes. Le données recueillies chez le rat Dumbo et comparées à celles du rat Wistar sont susceptibles de constituer de précieuses informations éventuellement transposables à l’espèce humaine. La première étape de cette étude a consisté en des analyses morphologiques et morphométriques afin de vérifier les perturbations morphologiques communes entre les rats Dumbo et les syndromes malformatifs humains : la brièveté des os zygomatique, maxillaire, mandibulaire et la position basse des oreilles. Ces analyses ont été réalisées sur les squelettes embryonnaires âgés de 16 jours à 21 jours de rats Dumbo et Wistar à l’aide d’une coloration in toto au Bleu Alcian – Alizarine. La deuxième étape de cette étude consistait en une analyse cytogénétique. Pour ce faire, nous avons établi le caryotype du rat Dumbo et nous l’avons comparé avec le caryotype du rat Wistar. L’étape suivante fut de procéder à l’analyse histologique des malformations crânio-faciales chez le rat Dumbo en observant la chondrogenèse pendant la morphogenèse crânio-faciale. Enfin, l’examen de l’expression des gènes Msx1 sens (S) , Msx1 antisens (AS) et Dlx1 dans l’extrémité céphalique des rats Dumbo a été réalisé par les techniques de RT–PCR (Reverse Transcription Polymerase Chain Reaction method). Des estimations semi-quantitatives ont été validées en utilisant des dilutions ADNc du rat Wistar. Des densitométries de la densité d’amplicons fluorescence ont été réalisées à l’aide du logiciel VilberLourmat Bio1D software. Les résultats obtenus ont permis de caractériser de manière précise les malformations crânio-faciales chez le rat Dumbo. 1- l’analyse céphalométrique sur les squelettes embryonnaires met en évidence une réduction des dimensions de certaines structures crânio-faciales chez le rat Dumbo : os mandibulaire, maxillaire, zygomatique, ainsi qu’on l’observe également dans le syndrome de Treacher Collins. 2- l’analyse cytogénétique par les techniques de banding G ne montre pas une différence entre le caryotype de Dumbo et le caryotype de rat Wistar (le contrôle). 3- l’analyse histologique de têtes d’embryons montre un retard dans les processus de la chondrification et de l’ossification pendant la morphogenèse crânio-faciale avec une croissance retardée des ébauches oculaires et des bourgeons dentaires. 4- l’analyse de l’expression génique de certains gènes homéobox (Msx1 S et AS) et Dlx1 montre une réduction de ces expressions pendant la morphogenèse crânio-faciale chez le rat Dumbo en comparaison avec la morphogenèse normale dans la souche Wistar.
183

Prevention of Head Injuries - focusing Specifically on Oblique Impacts

Aare, Magnus January 2003 (has links)
The massive number of injuries sustained in trafficaccidents is a growing problem worldwide, especially indeveloping countries. In 1998, more than one million peoplewere killed in traffic accidents worldwide, while about tentimes as many people were injured. Injuries to the centralnervous system and in particular to the headare especiallycritical to human life. This thesis contains five researchpapers looking at head injuries and head protection, proposingnew and more efficient ways of protecting the head, especiallyin traffic accidents. In order to define the national dimensions of the patternsof injuries incurred in motorcycle and moped accidents inSweden, a statistical survey was performed on data spanning a13-year period (Paper A). In Sweden, 27,100 individualsreceived in-patient care for motorcycle and moped accidentinjuries between 1987 and 1999. The motorcycle and moped injuryrate reduced in the second half of the study period, so toowere the total number of days of treatment per year. Males hadeight times the incidence of injuries of females. Head injurieswere the single most frequent diagnosis, followed by fracturesof the lower limbs. Concussion was the most frequent headinjury. These statistics clearly show the need for better headinjury prevention systems. According to the statistics, the most common type of impactto the head in motorcycle and moped accidents is an obliqueimpact. Oblique impacts generate rotations of the head, whichare a common cause of the most severe head injuries. Thereforea new test rig was constructed to reproduce oblique impacts toa helmeted dummy head, simulating those occurring in real lifeaccidents (Paper B). The new test rig was shown to provideuseful data at speeds of up to 50 km/h and with impact anglesvarying from purely tangential to purely radial. Thisinnovative test rig appears to provide an accurate method formeasuring accelerations in oblique impacts to helmets. When testing the performances of motorcycle helmets,discrepancies are usually seen in the test results. In order toevaluate these discrepancies, the finite element method (FEM)was used for simulations of a few oblique helmet impacts (PaperC). Amongthe parameters studied, the coefficients of frictionbetween the impacting surface and the helmet and between thehead and the helmet had the most significant influence on therotational accelerations. Additionally, a thinner andconsequently also weaker shell and a weaker liner, providedbetter protection for the impacts studied. Since there are no generally accepted global injurythresholds for oblique impacts to the human head, a study wasdesigned to propose new injury tolerances accounting for bothtranslations and rotations of the head (Paper D). In thatstudy, FE models of (a) a human head, (b) a Hybrid III dummyhead, and (c) the experimental helmet were used. Differentcriteria were proposed for different impact scenarios. Both thetranslational and the rotational effects were found to beimportant when proposing a predictor equation for the strainlevels experienced by the human brain in simulated impacts tothe head. In order to reduce the level of head injuries in society andto better understand helmet impacts from different aspect, aballistic impact was also studied (Paper E). The effects ofdifferent helmet shell stiffness and different angles ofimpacts were simulated. In this study, the same FE head modelfrom Paper D was used, however here it was protected with amodel of a composite ballistic helmet. It was concluded thatthe helmet shell should be stiff enough to prevent the insideof the shell from striking the skull, and that the strainsarising in the brain tissue were higher for some obliqueimpacts than for purely radial ones. In conclusion, this thesis describes the injury pattern ofmotorcycle and moped accidents in Sweden. This thesis showsthat the injuries sustained from these accidents can bereduced. In order to study both translational as well asrotational impacts, a new laboratory test rig was designed. Byusing the finite element method, it is possible to simulaterealistic impacts to the head and also to predict how severehead injuries may potentially be prevented.
184

Human Emotion Recognition from Body Language of the Head using Soft Computing Techniques

Zhao, Yisu 31 October 2012 (has links)
When people interact with each other, they not only listen to what the other says, they react to facial expressions, gaze direction, and head movement. Human-computer interaction would be enhanced in a friendly and non-intrusive way if computers could understand and respond to users’ body language in the same way. This thesis aims to investigate new methods for human computer interaction by combining information from the body language of the head to recognize the emotional and cognitive states. We concentrated on the integration of facial expression, eye gaze and head movement using soft computing techniques. The whole procedure is done in two-stage. The first stage focuses on the extraction of explicit information from the modalities of facial expression, head movement, and eye gaze. In the second stage, all these information are fused by soft computing techniques to infer the implicit emotional states. In this thesis, the frequency of head movement (high frequency movement or low frequency movement) is taken into consideration as well as head nods and head shakes. A very high frequency head movement may show much more arousal and active property than the low frequency head movement which differs on the emotion dimensional space. The head movement frequency is acquired by analyzing the tracking results of the coordinates from the detected nostril points. Eye gaze also plays an important role in emotion detection. An eye gaze detector was proposed to analyze whether the subject's gaze direction was direct or averted. We proposed a geometrical relationship of human organs between nostrils and two pupils to achieve this task. Four parameters are defined according to the changes in angles and the changes in the proportion of length of the four feature points to distinguish avert gaze from direct gaze. The sum of these parameters is considered as an evaluation parameter that can be analyzed to quantify gaze level. The multimodal fusion is done by hybridizing the decision level fusion and the soft computing techniques for classification. This could avoid the disadvantages of the decision level fusion technique, while retaining its advantages of adaptation and flexibility. We introduced fuzzification strategies which can successfully quantify the extracted parameters of each modality into a fuzzified value between 0 and 1. These fuzzified values are the inputs for the fuzzy inference systems which map the fuzzy values into emotional states.
185

The Effect of Inbound Mass on the Dynamic Response of the Hybrid III Headform and Brain Tissue Deformation

Karton, Clara 07 December 2012 (has links)
The varied impact parameters that characterize an impact to the head have shown to influence the resulting type and severity of outcome injury, both in terms of the dynamic response, and the corresponding deformation of neural tissue. Therefore, when determining head injury risks through event reconstruction, it is important to understand how individual impact characteristics influence these responses. The effect of inbound mass had not yet been documented in the literature. The purpose of this study was to determine the effects of inbound mass on the dynamic impact response and brain tissue deformation. A 50th percentile Hybrid III adult male head form was impacted using a simple pendulum system. Impacts to a centric and a non-centric impact location were performed with six varied inbound masses at a velocity of 4.0 m/s. The peak linear and peak angular accelerations were measured. A finite element model, (UCDBTM) was used to determine brain deformation, namely peak maximum principal strain and peak von Mises stress. Inbound mass produced significant differences for peak linear acceleration for centric (F(5, 24) = 217.55, p=.0005) and non-centric (F(5, 24) = 161.98, p=.0005), and for peak angular acceleration for centric (F(5, 24) = 52.51, p=.0005) and non-centric (F(5, 24) = 4.18, p=.007) impact locations. A change in inbound mass also had a significant effect on peak maximum principal strain for centric (F(5, 24) = 11.04, p=.0005) and non-centric (F(5, 24) = 5.87, p =.001), and for peak von Mises stress for centric (F(5, 24) = 24.01, p=.0005) and non-centric (F(5, 24) = 4.62, p=.004) impact locations. These results indicate the inbound mass of an impact should be of consideration when determining risks and prevention to head and brain injury.
186

Primary Blast Injury of the Head: Numerical Prediction and Evaluation of Protection

Lockhart, Philip A. January 2010 (has links)
The prevalence of injuries sustained from blast have been increasing over the past few decades due to the increasing use of Improvised Explosive Devices in areas where peacekeepers are deployed, as well as terrorist bombing incidents. The scope of this project was to evaluate the potential for head injury from primary effects in blast environments and to investigate protective aspects of protective equipment and new potential protective designs to mitigate or reduce the likelihood of Traumatic Brain Injury (TBI). In order to meet these goals, methods of blast loading as well as the kinematic response of the head when subjected to blast loading were investigated numerically and validated against experimental data. This was done for both low and mid heights of burst at varying standoff distances. The methods of loading considered were the basic spherical air burst formulation of the CONventional WEaPons algorithm (CONWEP), an advanced version of the algorithm that included ground reflection and mach stem formation, and a hemispherical surface burst which included ground reflection. The method that produced the most consistent results compared to the experiments was the enhanced version of CONWEP for mid level heights of burst; however, for low heights of burst, a novel “mirrored charge” setup provided the most accurate predictions. The kinematic response of the GEBOD numerical human body model, a rigid body representation of a 50th percentile male, was validated against experimental tests conducted by Defense Research and Development Canada (DRDC) for a range of standoff distances and Heights of Burst. It was found the response of the GEBOD was in good agreement with the DRDC experiments for peak acceleration, impulse and the Head Injury Criterion. The kinematic response of the head was investigated for various charge locations to study the effects of height of burst, lateral distance and standoff distance to the charge using the GEBOD numerical human body model. It was found that the standoff and height of burst had the largest influence on the acceleration experienced by the head. The height of burst study showed a large jump in the HIC15 injury criterion and head acceleration values when the charge was detonated within the region where a mach stem would form. As would be expected for the standoff distance from the charge, the closer the charge was to the body, the higher the accelerations experienced. A quasi two dimensional model of the human head at the mid-sagittal plane was developed in order to evaluate response at the tissue level, and the effect of protection. The sagittal head model was used to examine wave interactions in the fluid flow around the head during a blast event. This was achieved by utilizing an Arbitrary Langrangian-Eulerian formulation to model the blast loading. This model was also validated against experimental data such that it demonstrated the same kinematic response as the experimental tests under identical blast loading conditions. A helmet model was coupled to the sagittal head model using a layer of foam, and a statistical study was performed to determine the main effects and any interaction effects for the parameters of the numerical foam model. By analyzing these parameters and combining the best values for the effects, an optimum foam model was determined. This foam model was compared to actual foam materials and aluminum foam was found to have the closest properties to the idealized model. The aluminum foam material model was placed into the existing sagittal model and was found to have decreased the acceleration seen by the head under all the different loading cases considered. The maximum principal strain in the brain and the maximum intracranial pressure were also examined and compared to proposed injury criterion. For implementation in a helmet, an additional layer of comfort foam or some other soft material would have to be added between the head and the aluminum foam to prevent it from cutting or injuring the person. Some of the polymeric foams investigated could be used instead of aluminum foam; however, more data is required to properly define the material response at high strain rate loading. This study has shown that blast loading to the head can result in significant accelerations which could result in injury. By using common materials in the existing form of head protection, this potential for injury can be reduced.
187

Att lära är mer än utbildningar och kurser : En kvalitativ studie om äldreomsorgens enhetschefers syn på att lära i arbetet

Jansson, Annika, Revelj, Hanna January 2010 (has links)
The aim of our study has been to examine the care managers’ attitude to in- service training. We also wanted to see which factors the care managers and a member of the administrative head think influences this. The question formulations in the study were; what does in- service training mean for care managers and the administrative head, what was their attitude against it and which assumptions does the administrative head give to care managers for in- service training. The study is based on qualitative interviews with care managers and with a member of the administrative head. To interpret the material we have been using earlier studies, Senges theory of learning organization and Marsick and Watkins theory about informal and incidental learning. A main result is that the care managers obtain a great deal of possibilities to in- service training, for example meetings, educations and courses. The study also shows that the organization priorities formal learning while the care managers emphasise learning through interaction with other people, for example cohorts, contributors and users. Both care managers and a member of the administrative head says that there is a weakness in terms of follow- up and assessment. One recurrent topic in these discussions is responsibility, but the informants is not united of who’s the responsibility actually is.
188

Impact Analysis of Various Centers of Gravity in the Golf Club Head

Chen, Kuan-hong 29 August 2010 (has links)
The center of gravity (CG) in the golf club head is crucial to the launch angle, launch velocity and spin of golf balls after the golf impact. The CG locations in this study refer to the depth of CG, height of CG and distance of CG, which were determined by the change of shell thickness of a golf club head. By means of the finite element method (FEM), the researcher analyzed the impact process for golf balls and golf head clubs. Then he discussed the relationship between club heads and ball behaviors after impact. He also simulated the trajectory by the numerical method on the basis of the impact results of the golf ball. To sum up, a longer carry was generalized by deeper CG, lower CG and higher loft angle for a golfer with a slow club head speed. A shallower CG, higher CG and lower loft on a club head for a golfer with a fast club head speed were also verified in this study. Finally, a series of impacts produced by FEM and numerical method were generalized. Specifically, the method can be used to predict the flying distance of golf ball. It also can help predict the proper CG locations for golf club head designing.
189

Analysis of impact effect to Varied shape of Golf Club head

Chang, Ting-jang 07 July 2004 (has links)
The purpose of this study is to investigate the function of the different structural designs of golf club head models (including a deep head, a shallow back, and a shallow head) and to get the optimum golf club head through the software simulation. By means of software SolidWorks, the researcher draws three main club head models. The C ++ was used for a linear programming to control the golf club head thickness including an impact face, a crown, a sole, a toe and a heel under the definite weight. The simulation also helps adjust the center of gravity position of the golf club head and integrates with the finite element method software LS_Dyna in analyzing the impact procedure between the golf club head and the golf ball. In addition, the researcher preceded the analysis by replacing the crown surface as carbon fiber reinforcement polymers (CFRP). He also investigated the off-centered hit effects through the impact analysis. It is expected that study findings can be extracted. Through the simulation of the hit effects, the golf club head designers will be inspired to create more effective golf club heads.
190

Design and Manufacture of a Cam Type Linear Actuator

Tsai, Meng-Che 02 September 2004 (has links)
The drawbacks of the mechanical linear actuator which is applied to punch flexible printed circuit boards(FPCBs), are many components involved, low transmission efficient, and high proportion of energy consumption. In order to design and manufacture a device that can generate a rapid and high quality punching processes, the fundamental rules that can be followed are to use few parts with light weight design, good working piece, energy conserved, and perfect efficient. To improve the kinematic and dynamic characteristics of the existing mechanism, design, manufacture, and assessment are to be taken for developing new linear actuated mechanisms. The first step is to analyze the performance of the existing linkage actuator . The second step is to design a over-head cam mechanism of non-constant rotational speed to substitute the pulley and the rock arm according to the design specifications. The performance of the new type actuated device is superior to the existing mechanism, and this research had preliminary verified the viewpoint of the energy in high speed punching. The achievements of this research also provide references for linear actuator designers and high speed punching producers.

Page generated in 0.0608 seconds