Development of Force Concept

Development of Force Concept tài liệu, giáo án, bài giảng , luận văn, luận án, đồ án, bài tập lớn về tất cả các lĩnh vực...

THE TEXTUAL DEVELOPMENT OF NON-STEREOTYPIC CONCEPTS Karin Haenelt and Michael K6nyves T6th Integrated Publication and Information Systems Institute (IPSI) GMD Dolivostral]e 15, D 6100 Darmstadt, Germany haenelt@ipsi.darmstadt.gmd.dbp.de koenyves@ipsi.darmstadt.gmd.dbp.de tel. ++49/(0)6151/875-811, fax -818 ABSTRACT In this paper the text theoretical foundation of our text analysis system KONTEXT is described. The basic premise of the KONTEXT model is that new concepts are communicated by using the mechanisms of text constitution. The text model used assumes that the information conveyed in a text and the information describing its contextual organization can be structured into five layers (sentence structure, information on thematic pro- gression, referential structure, conceptual repre- sentation of the text and conceptual background knowledge). The text analysis component con- structs and traverses the information of these lay- ers under control of the discourse development. In this way, it can incrementally construct a textual view on knowledge, rather than only recognizing precoded concepts. 1 INTRODUCTION In the field ofknowledge-bMed text analysis it has been regarded as insufficient to analyze a text against the background of static and stereotypic default assumptions for some time (cf. [Hell- wig84], [Scha/Bruce/Polanyi87]). By applying this method the pre coded concepts are invoked again and again during the process of text analysis, regardless of the changes land the new concepts being constituted by the ongoing text. The func- tion of a text, however, is not confined to concept selection as in current knowledge-based applica- tions. In addition, textual mechanisms are used to operate on concepts and to compose them to actual contexts, i.e. to constitute (new) concepts. Textu- ally the contexts are established by the thematic and by the referential structure. Thus, new mecha- nisms are required which permit the textual orga- nization to control the creation and manipulation of concepts in text processing. In a way, this is to tie linguistic and knowledge,-based approaches to text processing together into a single method. 2 THE KONTEXT MODEL The basic premise of the KONTEXT model is that the relationship of expression and concept are changed during a text and concepts are communi- cated by using the mechanisms of text constitu- tion. The KONTEXT model is based on the as- sumption that • the information conveyed in a text and the information describing its contextual orga- nization can be structured into five layers. They define the sentence structure, informa- tion on thematic progression, the referential structure, the conceptual representation of the text and the conceptual background knowledge; • discourse provides the basic mechanisms by which concepts are constructed. Discourse is defined as sequences of transitions be- tween discourse states and discourse states are defined by the information represented in the layers. The text analysis component constructs and traverses the information of these layers under control of the discourse development. In this way, it can incrementally construct a textual view on knowledge, rather than only recognizing pre- coded concepts. We will now describe the layers of the text repre- - 263 - sentation. In the following section we discuss the conception of discourse in more detail. 2.1 LAYERS OF TEXT REPRESENTA- TION There are five layers of text representation: sentence structure thematic structure referential structure view background knowledge The lowest layer is the basis for textual com- munication. It is a formal representation of con- cepts modeling an open world and serves as Development of Force Concept Development of Force Concept Bởi: OpenStaxCollege Dynamics is the study of the forces that cause objects and systems to move To understand this, we need a working definition of force Our intuitive definition of force—that is, a push or a pull—is a good place to start We know that a push or pull has both magnitude and direction (therefore, it is a vector quantity) and can vary considerably in each regard For example, a cannon exerts a strong force on a cannonball that is launched into the air In contrast, Earth exerts only a tiny downward pull on a flea Our everyday experiences also give us a good idea of how multiple forces add If two people push in different directions on a third person, as illustrated in [link], we might expect the total force to be in the direction shown Since force is a vector, it adds just like other vectors, as illustrated in [link](a) for two ice skaters Forces, like other vectors, are represented by arrows and can be added using the familiar head-to-tail method or by trigonometric methods These ideas were developed in Two-Dimensional Kinematics Part (a) shows an overhead view of two ice skaters pushing on a third Forces are vectors and add like other vectors, so the total force on the third skater is in the direction shown In part (b), we see a free-body diagram representing the forces acting on the third skater [link](b) is our first example of a free-body diagram, which is a technique used to illustrate all the external forces acting on a body The body is represented by a single isolated point (or free body), and only those forces acting on the body from the outside (external forces) are shown (These forces are the only ones shown, because only 1/3 F Development of Force Concept external forces acting on the body affect its motion We can ignore any internal forces within the body.) Free-body diagrams are very useful in analyzing forces acting on a system and are employed extensively in the study and application of Newton’s laws of motion A more quantitative definition of force can be based on some standard force, just as distance is measured in units relative to a standard distance One possibility is to stretch a spring a certain fixed distance, as illustrated in [link], and use the force it exerts to pull itself back to its relaxed shape—called a restoring force—as a standard The magnitude of all other forces can be stated as multiples of this standard unit of force Many other possibilities exist for standard forces (One that we will encounter in Magnetism is the magnetic force between two wires carrying electric current.) Some alternative definitions of force will be given later in this chapter The force exerted by a stretched spring can be used as a standard unit of force (a) This spring has a length x when undistorted (b) When stretched a distance Δx, the spring exerts a restoring force, restore, which is reproducible (c) A spring scale is one device that uses a spring to measure force The force restore is exerted on whatever is attached to the hook Here restore has a magnitude of units in the force standard being employed Take-Home Experiment: Force Standards To investigate force standards and cause and effect, get two identical rubber bands Hang one rubber band vertically on a hook Find a small household item that could be attached to the rubber band using a paper clip, and use this item as a weight to investigate the stretch of the rubber band Measure the amount of stretch produced in the rubber band with one, two, and four of these (identical) items suspended from the rubber band What is the relationship between the number of items and the amount of stretch? How large a stretch would you expect for the same number of items suspended from two rubber bands? What happens to the amount of stretch of the rubber band (with the weights attached) if the weights are also pushed to the side with a pencil? Section Summary • Dynamics is the study of how forces affect the motion of objects • Force is a push or pull that can be defined in terms of various standards, and it is a vector having both magnitude and direction 2/3 Development of Force Concept • External forces are any outside forces that act on a body A free-body diagram is a drawing of all external forces acting on a body Conceptual Questions Propose a force standard different from the example of a stretched spring discussed in the text Your standard must be capable of producing the same force repeatedly What properties forces have that allow us to classify them as vectors? 3/3 BioMed Central Page 1 of 10 (page number not for citation purposes) Health and Quality of Life Outcomes Open Access Research Exploring disability from the perspective of adults living with HIV/AIDS: Development of a conceptual framework Kelly K O'Brien* 1,2 , Ahmed M Bayoumi 1,2 , Carol Strike 3,4 , Nancy L Young 1,5 and Aileen M Davis 1,6 Address: 1 Department of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada, 2 Centre for Research on Inner City Health, St. Michael's Hospital, 30 Bond Street, Toronto, Ontario, M5B 1X8, Canada, 3 Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada, 4 Centre for Addiction and Mental Health, 33 Russell St., 3rd Floor Tower, Toronto, Ontario, M5S 2S1, Canada, 5 School of Rural and Northern Health, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario, P3E 2C6, Canada and 6 Division of Health Care and Outcomes Research and Arthritis and Community Research and Evaluation Unit, Toronto Western Research Institute, 399 Bathurst Street - MP11-322, Toronto, Ontario, M5T 2S8, Canada Email: Kelly K O'Brien* - kelly.obrien@utoronto.ca; Ahmed M Bayoumi - ahmed.bayoumi@utoronto.ca; Carol Strike - Carol_Strike@camh.net; Nancy L Young - nyoung@laurentian.ca; Aileen M Davis - adavis@uhnresearch.ca * Corresponding author Abstract Background: Since the advent of combination antiretroviral therapy, in developed countries HIV increasingly is perceived as a long-term illness. Individuals may experience health-related consequences of HIV and its associated treatments, a concept that may be termed disability. To date, a comprehensive framework for understanding the health-related consequences experienced by people living with HIV has not been developed. The purpose of this research was to develop a conceptual framework of disability from the perspective of adults living with HIV. Methods: We conducted four focus groups and 15 face-to-face interviews with 38 adults living with HIV. We asked participants to describe their health-related challenges, their physical, social and psychological areas of life affected, and impact on their overall health. We analyzed data using grounded theory techniques. We also conducted two validity check focus groups with seven returning participants. Results: Disability was conceptualized by participants as multi-dimensional and episodic characterized by unpredictable periods of wellness and illness. The Episodic Disability Framework consisted of three main components: a) dimensions of disability that included symptoms and impairments, difficulties carrying out day-to-day activities, challenges to social inclusion, and uncertainty that may fluctuate on a daily basis and over the course of living with HIV, b) contextual factors that included extrinsic factors (social support and stigma) and intrinsic factors (living strategies and personal attributes) that may exacerbate or alleviate disability, and c) triggers that initiate momentous or major episodes of disability such as receiving an HIV diagnosis, starting or changing medications, experiencing a serious illness, and suffering a loss of others. Conclusion: The Episodic Disability Framework considers the variable nature of disability, acknowledges uncertainty as a key component, describes contextual factors that influence experiences of disability, and considers life events that may initiate a major or momentous episode. This This Provisional PDF corresponds to the article as it appeared upon acceptance. Copyedited and fully formatted PDF and full text (HTML) versions will be made available soon. A validity-driven approach to the understanding of the personal and societal burden of low back pain: development of a conceptual and measurement model Arthritis Research & Therapy 2011, 13:R152 doi:10.1186/ar3468 Rachelle Buchbinder (rachelle.buchbinder@monash.edu) Roy Batterham (roy.batterham@deakin.edu.au) Gerald Elsworth (gerald.elsworth@deakin.edu.au) Clermont E Dionne (clermont.dionne@uresp.ulaval.ca) Emma Irvin (eirvin@iwh.on.ca) Richard H Osborne (richard.osborne@deakin.edu.au) ISSN 1478-6354 Article type Research article Submission date 16 June 2011 Acceptance date 20 September 2011 Publication date 20 September 2011 Article URL http://arthritis-research.com/content/13/5/R152 This peer-reviewed article was published immediately upon acceptance. It can be downloaded, printed and distributed freely for any purposes (see copyright notice below). Articles in Arthritis Research & Therapy are listed in PubMed and archived at PubMed Central. For information about publishing your research in Arthritis Research & Therapy go to http://arthritis-research.com/authors/instructions/ Arthritis Research & Therapy © 2011 Buchbinder et al. ; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A validity-driven approach to the understanding of the personal and societal burden of low back pain: development of a conceptual and measurement model Rachelle Buchbinder 1,2,*,# , Roy Batterham 3,* , Gerald Elsworth 3 , Clermont E. Dionne 4,6 , Emma Irvin 5 , Richard H. Osborne 3 , 1. Department of Clinical Epidemiology, Cabrini Hospital, 183 Wattletree Rd, Malvern, Victoria, 3144, Australia 2. Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University Suite 41, 183 Wattletree Rd, Malvern, Victoria, 3144, Australia 3. Public Health Innovation, Faculty of Health, Deakin University, 221 Burwood Highway, Burwood, Victoria, 3125 Australia 4. Population Health Research Unit (URESP), Research Centre of the Laval University Affiliated Hospital, Hôpital du St-Sacrement, 1050 chemin Ste-Foy, Québec (QUE) G1S 4L8, Canada 5. Institute for Work & Health, 81 University Avenue, Suite 800, Toronto, Ontario, M5G 2E9, Canada 6. Department of Rehabilitation, Faculty of Medicine, Laval University, Hôpital du St- Sacrement, 1050 chemin Ste-Foy, Québec (QUE) G1S 4L8, Canada # Corresponding author: rachelle.buchbinder@monash.edu * Equal contributors Abstract Introduction: While the importance and magnitude of the burden of low back pain upon the individual is well recognized, a systematic understanding of the impact of the condition on individuals is currently hampered by the lack of an organized understanding of what aspects of a person’s life are affected, and comprehensive measures of these effects. The aim of this study was to develop a conceptual and measurement model of the overall burden of low back pain from the individual’s perspective using a validity-driven approach. Methods: To define the breadth of low back pain burden we conducted three concept- mapping workshops to generate an item pool. Two face-to-face workshops (Australia) were conducted with people with low back pain, and clinicians and policy makers respectively. A third (USA) was held with international multidisciplinary experts. Multidimensional scaling, cluster analysis, participant input and thematic analyses organized participants’ ideas into clusters of ideas which then informed the conceptual model. Results: One hundred and ninety-nine statements This Provisional PDF corresponds to the article as it appeared upon acceptance. Copyedited and fully formatted PDF and full text (HTML) versions will be made available soon. Importance of cumulative exposure to elevated cholesterol and blood pressure in development of atherosclerotic coronary artery disease in systemic lupus erythematosus: a prospective proof-of-concept cohort study Arthritis Research & Therapy 2011, 13:R156 doi:10.1186/ar3473 Mandana Nikpour (mnikpour@medstv.unimelb.edu.au) Murray B Urowitz (m.urowitz@utoronto.ca) Dominique Ibanez (dibanez@uhnres.utoronto.ca) Paula J Harvey (paula.harvey@uhn.on.ca) Dafna D Gladman (dafna.gladman@utoronto.ca) ISSN 1478-6354 Article type Research article Submission date 3 June 2011 Acceptance date 29 September 2011 Publication date 29 September 2011 Article URL http://arthritis-research.com/content/13/5/R156 This peer-reviewed article was published immediately upon acceptance. It can be downloaded, printed and distributed freely for any purposes (see copyright notice below). Articles in Arthritis Research & Therapy are listed in PubMed and archived at PubMed Central. For information about publishing your research in Arthritis Research & Therapy go to http://arthritis-research.com/authors/instructions/ Arthritis Research & Therapy © 2011 Nikpour et al. ; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Importance of cumulative exposure to elevated cholesterol and blood pressure in development of atherosclerotic coronary artery disease in systemic lupus erythematosus: a prospective proof-of-concept cohort study Mandana Nikpour 1,2 , Murray B Urowitz 1,# , Dominique Ibanez 1 , Paula J Harvey 3 and Dafna D Gladman 1 . 1 University of Toronto Lupus Clinic and the Centre for Prognosis Studies in the Rheumatic Diseases, Toronto Western Hospital, 399 Bathurst Street, Toronto, ON, M5T 2S8, Canada 2 The University of Melbourne Departments of Medicine and Rheumatology, St. Vincent's Hospital, 41 Victoria Parade, Fitzroy, Melbourne, Victoria, 3065, Australia 3 Division of Cardiology and Clinical Pharmacology, Toronto Western Hospital, 399 Bathurst Street, Toronto, ON, M5T 2S8, Canada # Corresponding author: m.urowitz@utoronto.ca Abstract Introduction: Previous studies have shown that traditional risk factors such as hypercholesterolemia and hypertension account for only a small proportion of the dramatically increased risk of atherosclerotic coronary artery disease (CAD) in systemic lupus erythematosus (SLE). However, in these studies, exposure to risk factors was measured only at baseline. In this study, our objective was to compare measures of cumulative exposure with remote and recent values for each of total cholesterol (TC), systolic (SBP) and diastolic (DBP) blood pressure in terms of ability to quantify risk of atherosclerotic CAD in patients with SLE. Methods: Patients in the Toronto lupus cohort had TC and BP measured at each clinic visit and were followed prospectively for the occurrence of CAD. For each patient, arithmetic mean, time-adjusted mean (AM) and area-under-the-curve (AUC) were calculated for serial TC, SBP and DBP measurements. Proportional hazards regression models were used to compare these summary measures with recent and first available (‘remote’) measurements in terms of ability to quantify risk of CAD events, defined as myocardial infarction, angina or sudden cardiac death. Results: There were 991 patients with mean±SD of 19±19 TC measurements per patient. Over a follow-up of 6.7±6.4 years, there were 86 CAD events. While remote TC was not significantly predictive of CAD, mean and AM TC were more strongly predictive (hazard ratio [HR] 2.07, SUPPLY CHAIN RESILIENCE: DEVELOPMENT OF A CONCEPTUAL FRAMEWORK, AN ASSESSMENT TOOL AND AN IMPLEMENTATION PROCESS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University by Timothy J. Pettit, M.S. * * * * * The Ohio State University 2008 Dissertation Committee: Professor Keely L. Croxton, Adviser Professor Martha C. Cooper Professor Joseph Fiksel Approved by Professor Walter Zinn _________________________ Adviser Graduate Program in Business Administration Copyright by Timothy J. Pettit 2008 The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Air Force, the Department of Defense, or the U.S. Government ii ABSTRACT The business environment is always changing and change creates risk. Managing the risk of the uncertain future is a challenge that requires resilience – the ability to survive, adapt and grow in the face of turbulent change. Academics and industry leaders have seen the need to supplement traditional risk management techniques with the concept of resilience that is better designed to cope with extreme complexities, unpredictable events and adaptive threats. However, without standardized definitions, accepted variables or measurement tools, supply chain resilience is merely a theoretical concept. This dissertation will explore the current thought on supply chain resilience and develop the construct into a managerial process for implementation. In Phase I, the Supply Chain Resilience Framework was developed to provide a conceptual framework based on extant literature and refined through a focus group methodology. Findings suggest that supply chain resilience can be assessed in terms of two dimensions: vulnerabilities and capabilities. Research identified seven vulnerability factors composed of 40 specific attributes and 14 capability factors from 71 attributes that facilitate the measurement of resilience. Phase II created an assessment tool based on this framework – the Supply Chain Resilience Assessment and Management (SCRAM TM ). Data gathered from seven global manufacturing supply chains was used to assess their current state of supply chain iii resilience. The tool was validated using a qualitative methodology comparing assessment scores to 1,369 items recorded from discussions of 14 recent disruptions. Phase III concluded the research project by identifying critical linkages between the inherent vulnerability factors and controllable capability factors. Accomplished through a mixed-method triangulation of theoretical linkages, assessment correlations and focus group connections, research identified 311 specific linkages that can be used to guide a resilience improvement process. An implementation process is proposed to guide supply chain leaders toward the goal of creating and maintaining a dynamic state of balanced resilience by developing a portfolio of capabilities best matched to the pattern of inherent vulnerabilities. Exploratory data suggests that we can infer a correlation between increased resilience and improved supply chain performance. Each phase of this study concludes with discussion of limitations and recommendations for future research. iv DEDICATION Dedicated to my father and mother, Bob and Kathy Pettit, for supporting our family and sharing their commitment to education so we all could reach our full potential. v ACKNOWLEDGMENTS The impetus for this research began in late 2005 as the Center for Resilience at The Ohio State University hosted a symposium to begin their study on supply chain resilience. Dr. Joseph Fiksel, as co-director and now Executive Director, ... Development of Force Concept • External forces are any outside forces that act on a body A free-body diagram is a drawing of all external forces acting on a body Conceptual Questions Propose a force. .. the force it exerts to pull itself back to its relaxed shape—called a restoring force as a standard The magnitude of all other forces can be stated as multiples of this standard unit of force. ..F Development of Force Concept external forces acting on the body affect its motion We can ignore any internal forces within the body.) Free-body diagrams are very useful in analyzing forces