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Search Results: 1 - 10 of 5134 matches for " Joel Singer "
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Subdividing the Trefoil by Origami
Joel C. Langer,David A. Singer
Geometry , 2013, DOI: 10.1155/2013/897320
Abstract: In 2005, David Cox and Jerry Shurman proved that the curves they call -clovers can be subdivided into equal lengths (for certain values of ) by origami, in the cases where , 2, 3, and 4. In this paper, we expand their work to include the 6-clover. 1. Historical Background From antiquity, it was known that regular polygons with sides could be constructed with compass and (unmarked) straightedge for of one of the forms , and . In 1801, Gauss showed that the list could be expanded to include powers of two times any product of distinct Fermat primes, primes of the form . He claimed to have a proof of the converse statement, but as Pierpont noted ([1], p.79), he never actually provided it. Pierpont gives an elementary proof (i.e., without Galois theory) in his paper. In 1837, the French mathematician Pierre Wantzel resolved three celebrated ancient mathematical problems definitively, when he proved the impossibility of trisecting an arbitrary angle, duplicating the cube, or constructing a regular polygon with sides for values of other than those of Gauss using only a compass and (unmarked) straightedge. Remarkably, these same constructions can be achieved by the technique of origami (paper folding). In fact, using origami, it is also possible to trisect angles, duplicate cubes, and generally construct roots of cubic equations. This was observed by Beloch in a publication in 1936 [2]. An explication of Beloch’s work, including a survey of the history, can be found in [3]. Alternatively, with a marked straightedge, one can achieve the same result. Generalizing the notion of construction to include this or an equivalent tool and using Galois theory [4], the values of for which a regular polygon can be constructed consist of all numbers of the form where and are distinct primes of the form with , . Such primes are known as Pierpont primes. Meanwhile, Abel showed in 1828 that the lemniscate can also be divided into pieces of equal length with straightedge and compass for the same values of as for the circle. See [5] for a modern proof of this result, including the converse; see also [6]. The 2005 paper of Cox and Shurman [7] expands the family of divisible curves to include the clover. The -clover is the plane curve defined by the polar equation: where is a positive integer. This is a subfamily of the sinusoidal or sinus spirals ([8], p.194). For , the curve is the cardioid; is the circle; is the clover; is the Bernoulli lemniscate. In their paper, they prove that these first four curves can be divided into arcs of equal length by origami (paper-folding)
Comparing the content of participation instruments using the International Classification of Functioning, Disability and Health
Vanessa K Noonan, Jacek A Kopec, Luc Noreau, Joel Singer, Anna Chan, Louise C Masse, Marcel F Dvorak
Health and Quality of Life Outcomes , 2009, DOI: 10.1186/1477-7525-7-93
Abstract: A systematic literature search was conducted to identify instruments that assess participation according to the ICF. Instruments were considered to assess participation and were included if the domains contain content from a minimum of three ICF chapters ranging from Chapter 3 Communication to Chapter 9 Community, social and civic life in the activities and participation component. The instrument content was examined by first identifying the meaningful concepts in each question and then linking these concepts to ICF categories. The content analysis included reporting the 1) ICF chapters (domains) covered in the activities and participation component, 2) relevance of the meaningful concepts to the activities and participation component and 3) context in which the activities and participation component categories are evaluated.Eight instruments were included: Impact on Participation and Autonomy, Keele Assessment of Participation, Participation Survey/Mobility, Participation Measure-Post Acute Care, Participation Objective Participation Subjective, Participation Scale (P-Scale), Rating of Perceived Participation and World Health Organization Disability Assessment Schedule II (WHODAS II). 1351 meaningful concepts were identified in the eight instruments. There are differences among the instruments regarding how participation is operationalized. All the instruments cover six to eight of the nine chapters in the activities and participation component. The P-Scale and WHODAS II have questions which do not contain any meaningful concepts related to the activities and participation component. Differences were also observed in how other ICF components (body functions, environmental factors) and health are operationalized in the instruments.Linking the meaningful concepts in the participation instruments to the ICF classification provided an objective and comprehensive method for analyzing the content. The content analysis revealed differences in how the concept of participat
Pediatric Post-Discharge Mortality in Resource Poor Countries: A Systematic Review
Matthew O. Wiens, Shane Pawluk, Niranjan Kissoon, Elias Kumbakumba, J. Mark Ansermino, Joel Singer, Andrew Ndamira, Charles Larson
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0066698
Abstract: Objectives Mortality following hospital discharge is an important and under-recognized contributor to overall child mortality in developing countries. The primary objective of this systematic review was to identify all studies reporting post-discharge mortality in children, estimate likelihood of death, and determine the most important risk factors for death. Search Strategy MEDLINE and EMBASE were systematically searched using MeSH terms and keywords from the inception date to October, 2012. Key word searches using Google Scholar? and hand searching of references of retrieved articles was also performed. Studies from developing countries reporting mortality following hospital discharge among a pediatric population were considered for inclusion. Results Thirteen studies that reported mortality rates following discharge were identified. Studies varied significantly according to design, underlying characteristics of study population and duration of follow-up. Mortality rates following discharge varied significantly between studies (1%–18%). When reported, post-discharge mortality rates often exceeded in-hospital mortality rates. The most important baseline variables associated with post-discharge mortality were young age, malnutrition, multiple previous hospitalizations, HIV infection and pneumonia. Most post-discharge deaths occurred early during the post-discharge period. Follow-up care was examined in only one study examining malaria prophylaxis in children discharged following an admission secondary to malaria, which showed no significant benefit on post-discharge mortality. Conclusions The months following hospital discharge carry significant risk for morbidity and mortality. While several characteristics are strongly associated with post-discharge mortality, no validated tools are available to aid health workers or policy makers in the systematic identification of children at high risk of post-discharge mortality. Future research must focus on both the creation of tools to aid in defining groups of children most likely to benefit from post-discharge interventions, and formal assessment of the effectiveness of such interventions in reducing morbidity and mortality in the first few months following hospital discharge.
Inter- and Intra-Rater Reliability of the Australian Spasticity Assessment Scale in Adults with Acquired Brain Injury  [PDF]
Anya Calame, Barbara J. Singer
Open Journal of Therapy and Rehabilitation (OJTR) , 2015, DOI: 10.4236/ojtr.2015.33011
Abstract: Objective: This study investigated the inter- and intra-rater reliability of the Australian Spasticity Assessment Scale (ASAS) in adults with unilateral hypertonia following acquired brain injury. The ASAS has been shown to be superior to other clinical tools for the assessment of spasticity in children with cerebral palsy but reliability has not been previously examined in adults. Method: Four muscle groups were rated on one occasion by four assessors using the ASAS in sixteen adults with unilateral hypertonia following acquired brain injury. Twelve participants returned one week later for reassessment by the same assessors. Results: Overall inter-rater reliability of the ASAS using a quadratic weighted Kappa was moderate (Kqw 0.58) with ranges from moderate to good (Kqw 0.42 - 0.70). Agreement between raters was greatest for soleus muscle and least for wrist flexors. Overall intra-rater reliability of each of the four raters was moderate to good (Kqw 0.48 - 0.79). Agreement within raters was greatest for soleus muscle and least for biceps muscle. Conclusions: The ASAS may represent an appropriate alternative to the clinical scales currently used to assess spasticity; however inter and intra-rater reliability data from this investigation are lower than those which have previously been reported by experienced users of the ASAS in children with cerebral palsy. Further investigation with a larger sample size is warranted before any firm conclusions may be drawn about the reliability and validity of this tool to assess spasticity in adults with acquired brain injury.
Finite Element Wear Behavior Modeling of Al/Al2SiO5/C Chilled Hybrid Metal Matrix Composites (CHMMCs)  [PDF]
Joel Hemanth
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.27118
Abstract: This paper describes research on aluminum based metal matrix hybrid composites reinforced with kaolinite (Al2SiO5) and carbon (C) particulates cast using high rate heat transfer technique during solidification by employing metallic, non-metallic and cryogenic end chills. The effect of reinforcement and chilling on strength, hardness and wear behavior are discussed in this paper. It is discovered that cryogenic chilled MMCs with Al2SiO5-9 vol.%/C-3 vol.% dispersoid content proved to be the best in enhancing the mechanical and wear properties. A physically based Finite element (FE) model for the abrasive wear of the hybrid composite developed is based on the mechanisms associated with sliding wear of ductile aluminum matrix of the composite containing hard Al2SiO5 and soft carbon (dry lubricant) reinforcement particles. Finally the results reveal that there is a good agreement that exists between the simulated (FE) values and those of the experimental values, proving the suitability of the boundary conditions.
The Impact of ‘Violating the Heterosexual Norm’ on Reading Speed and Accuracy  [PDF]
Joel Dickinson
Psychology (PSYCH) , 2011, DOI: 10.4236/psych.2011.25071
Abstract: This study explores the impact of “schema non-congruent” content on reading speed that has been found in relation to non-stereotypical gender roles. The goal of the present study is to assess if this effect translates to material that violates the “heterosexual norm”. Further, the present study explores whether the impact can be minimized by providing context prior to the exposure of sentences. Data indicated that the impact of sexuality was dependent on the gender of the main character and whether participants had been primed with context or not. Regardless of the time taken to read sentences, accuracy of material was recalled at a constant rate. In conclusion, the activation of “heterosexuality” does seem to be an automatic process such as the activation of gender.
Heat Transfer Analysis during External Chilling of Composite Material Castings through Experimental and Finite Element (FE) Modelling  [PDF]
Joel Hemanth
Modeling and Numerical Simulation of Material Science (MNSMS) , 2014, DOI: 10.4236/mnsms.2014.41001
In controlled solidification, one of the important factors that affects heat transfer from the solidifying casting is the resistance offered at the casting/chill interface. In the present investigation, heat transfer analysis during solidification of Al-12%Si (LM 13) alloy is carried out by collecting temperature history of the solidifying casting. The temperature distribution during solidification in the present investigation is obtained using ANSYS multiphysics software and further for comparison. The temperature profiles are also obtained by FE (Finite Element) modelling using the same software. By using a temperature data logger and lab view based software, the temperature data is acquired and processed at every second. The cooling curves obtained are analysed to know the effect of chilling on solidification behaviour of Al-12%Si alloy castings. Finally, it is concluded from the above research that the cooling curves and temperature distribution obtained by FE analysis do not so closely converge with the experimental data due to modelling limitations.
Effect of Metallic, Nonmetallic, Water Cooled and Cryogenic Chills on Pearlite Content (PC), Eutectic Cell Count (ECC) and Grain Size (GS) of Hypo Eutectic Nickel Alloyed Cast Iron  [PDF]
Joel Hemanth
Modeling and Numerical Simulation of Material Science (MNSMS) , 2017, DOI: 10.4236/mnsms.2017.71001
Abstract: This paper presents the results obtained, deductions made from solidification behaviour and a series of micro structural studies such as pearlite content, eu-tectic cell count and grain size of hypoeutectic gray cast iron which was sand cast (CO2 moulding) using metallic, nonmetallic, water cooled and subzero (cryogenic) end chills. Hypo-eutectic cast irons containing C 3.42, Si 2.4 and Ni 1.5 with impurity contents (S, P, Mn etc.) were solidified unidirectionally in an American Foundrymen Society (AFS) standard mould, the end of which was provided with different end chills to study the effect of chilling during solidifi-cation. The melts were inoculated with 0.3% Fe-Si to promote graphitization. It was observed that the transition from one structure to another is more gradual than normally obtained in the structure of cast irons solidified mul-ti-directionally in a sand mould at room temperature. Austenite dendrite interactions were shown to be a major factor in determining the microstructure, in which the higher dendrite reaction leads to changes in DAS, ECC and GS. It is observed that, the number of eutectic cells is an index of graphite nucleation and the effect of these on structure, since the eutectic cells are developed on the graphite nuclei during solidification.
Scanning Electron Microscopy (SEM) Analysis and Hardness of Diffusion Bonded Titanium-Titanium and Titanium-Copper Plates with Static Force and without Interlayers  [PDF]
Joel Hemanth
Open Journal of Composite Materials (OJCM) , 2017, DOI: 10.4236/ojcm.2017.72007
Abstract: In the present research, commercially pure Ti (grade-2) has been diffusion bonded with Ti and Cu plate under static force without any interlayers. The diffusion bonded samples were tested for micro hardness and micro structural analysis through optical microscopy and SEM. It is found from the present investigation that the bonded zone is affected by the processing variables such as bonding time (1 - 2 h), bonding force (250 N), bonding temperature (973 - 1073 K) and surface roughness. Results of the investigation revealed that temperature range of ?973 - 1073 K along with time duration of 1 - 2 hours in vacuum has resulted in a joint having high hardness with minimum pores. Hardness of the bond depends on the grain boundary diffusion at the interface and maximum hardness was achieved in the case of Ti-Cu joints. When Ti-Cu plates were used for bonding at 973 K for 2 hours, Cu-Ti solid solution along with a zone of different intermetallics was formed in the bonded zone. However, at higher temperatures, no continuous zone of intermetallics was found in the bonded region but instead Ti-Cu solid solution appeared.
Experimental, Mathematical and Finite Element Analysis (FEA) of Temperature Distribution through Rectangular Fin with Circular Perforations  [PDF]
Joel Hemanth
Modeling and Numerical Simulation of Material Science (MNSMS) , 2017, DOI: 10.4236/mnsms.2017.72002
Abstract: Fins are the extended surfaces through which heat transfer takes place to keep the surface cool. Fins of various configurations are presently used ranging from automobile engine cooling to cooling of computer parts. Note that in a fin majority of the heat transfer to atmosphere is by convection and therefore in the present research, and importance is given to variation of temperature along the length of the fin which in turn gives rate of heat transfer. In the present research a solid rectangular aluminum fin and the same rectangular fin with different perforations (2, 4, 8 and 10) were compared analytically, experimentally and its validity through finite element analysis for its temperature distribution along the length. From the present research it is observed that the mathematical and FEA for a solid rectangular fin without perforations are converging within ±1°C and rectangular fin with 10 perforations are converging within ±2°C and hence the validity.
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