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Search Results: 1 - 10 of 57074 matches for " Peter Lee "
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Por que aprender História?
Lee, Peter;
Educar em Revista , 2011, DOI: 10.1590/S0104-40602011000500003
Abstract: knowing that nobody escapes from the past and the importance of the relationship that people establish with the past, this aimed to point out some fundaments for the meaning of history learning, based in researches related to history's philosophy. thus, themes such as the importance of history to validate the past, the relevance of evidences, the problematic of laws and generalizations and also the meaning of vicarial experience to build the learning of history were objects of analysis with the objective of showing why it is important to learn history.
La Imaginación Histórica
Peter Lee
Memoria y Sociedad , 2004,
Abstract: The article is centered on the connections problem between historical comprehension and historical imagination, from the double take on history as an academic exercise and its teaching. For historical knowledge to acquire a sense of communication and utility, as a condition, competence in historical comprehension is needed. It should presume a specific manner of relating with the past where the subjects of the present without getting compromised with the objectives and beliefs that are foreign to them, are perfectly capable of escaping their own prejudices and submerge themselves in a universe that in the beginning appears unfamiliar. For these objectives the author of the text pro poses empathy as an achievement and the use of imagination on three different levels as indispensable conditions. The article parts from the theoretical difficulties that represent imaginative thinking in history (the relationships given between imagination and evidence), and finally concludes, that without imagination, historical Knowledge will remain static.//El presente artículo está centrado en el problema de los vínculos dados entre la comprensión histórica y la imaginación histórica, desde la doble mirada de Ia historia como ejercicio académico y de la ense anza de la historia. Para que el saber histórico adquiera un sentido de comunicabilidad y de utilidad, se hace condición necesaria la eficiencia de la comprensión histórica. Ella supone una manera específica de relación con el pasado en donde los sujetos del presente, sin verse comprometidos con metas y creencias que les son ajenas, son perfectamente capaces de desprenderse de las suyas para sumergirse en un universo que en principio se les aparece como extra o. El autor del texto, propondrá como indispensable para ello una disposición a la empatía como logro, además del uso de la imaginación dada en tres niveles diferentes que se encuentran conectados entre sí: las cosas que se dan en la imaginación, las suposiciones y las cosas que se hacen con imaginación. El artículo partirá de las dificultades teóricas que representa pensar el uso de la imaginación en la historia (las relaciones dadas entre imaginación y evidencia), para concluir al final que sin imaginación, el conocimiento histórico permanece estático.
The Pure Virtual Braid Group Is Quadratic
Peter Lee
Mathematics , 2011, DOI: 10.1007/s00029-012-0107-1
Abstract: If an augmented algebra K over Q is filtered by powers of its augmentation ideal I, the associated graded algebra grK need not in general be quadratic: although it is generated in degree 1, its relations may not be generated by homogeneous relations of degree 2. In this paper we give a sufficient criterion (called the PVH Criterion) for grK to be quadratic. When K is the group algebra of a group G, quadraticity is known to be equivalent to the existence of a (not necessarily homomorphic) universal finite type invariant for G. Thus the PVH Criterion also implies the existence of such a universal finite type invariant for the group G. We apply the PVH Criterion to the group algebra of the pure virtual braid group (also known as the quasi-triangular group), and show that the corresponding associated graded algebra is quadratic, and hence that these groups have a (not necessarily homomorphic) universal finite type invariant.
Proof of a Conjectured Formula for the Alexander Invariant
Peter Lee
Mathematics , 2012,
Abstract: In this paper we prove the validity of a formula for computing the Alexander invariant which was originally conjectured by Bar-Natan and Dancso in [BND].
Closed-Form Associators in Permutative Chord Diagrams
Peter Lee
Mathematics , 2013,
Abstract: Construction of a universal finite-type invariant can be reduced, under suitable assumptions, to the solution of certain equations (the hexagon and pentagon equations) in a particular graded associative algebra of chord diagrams. An explicit, closed-form solution to these equations may, indirectly, give information about various interesting properties of knots, such as which knots are ribbon. However, while closed-form solutions (as opposed to solutions which can only be approximated to successively higher degrees) are needed for this purpose, such solutions have proven elusive, partly as a result of the non-commutative nature of the algebra. To make the problem more tractable, we restrict our attention to solutions of the equations in the subalgebra of horizontal chord diagrams, viewed as a graded unital permutative algebra -- where `permutative' means that u[x,y]=0 whenever u has degree at least 1. We show that this restriction leads in a straightforward and fairly short way to a reduction of the hexagon and pentagon equations to a simpler equation taken over the algebra of power series in two commuting variables. This equation had been found and solved explicitly by Kurlin under a superficially different set of reduction assumptions, which we show here are in fact equivalent to ours. This paper thus provides an alternative (simpler and shorter) derivation of Kurlin's equation.
On the Action of the Symmetric Group on the Cohomology of Groups Related to (Virtual) Braids
Peter Lee
Mathematics , 2013,
Abstract: In this paper we consider the cohomology of four groups related to the virtual braids of [Kauffman] and [Goussarov-Polyak-Viro], namely the pure and non-pure virtual braid groups (PvB_n and vB_n, respectively), and the pure and non-pure flat braid groups (PfB_n and fB_n, respectively). The cohomologies of PvB_n and PfB_n admit an action of the symmetric group S_n. We give a description of the cohomology modules H^i(PvB_n,Q) and H^i(PfB_n,Q) as sums of S_n-modules induced from certain one-dimensional representations of specific subgroups of S_n. This in particular allows us to conclude that H^i(PvB_n,Q) and H^i(PfB_n,Q) are uniformly representation stable, in the sense of [Church-Farb]. We also give plethystic formulas for the Frobenius characteristics of these S_n-modules. We then derive a number of constraints on which S_n irreducibles may appear in H^i(PvB_n,Q) and H^i(PfB_n,Q). In particular, we show that the multiplicity of the alternating representation in H^i(PvB_n,Q) and H^i(PfB_n,Q) is identical, and moreover is nil for sufficiently large $n$. We use this to recover the (previously known) fact that the multiplicity of the alternating representation in H^i(PB_n,Q) is nil (here PB_n is the ordinary pure braid group). We also give an explicit formula for H^i(vB_n,Q) and show that H^i(fB_n,Q)=0. Finally, we give Hilbert series for the character of the action of S_n on H^i(PvB_n,Q) and H^i(PfB_n,Q). An extension of the standard `Koszul formula' for the graded dimension of Koszul algebras to graded characters of Koszul algebras then gives Hilbert series for the graded characters of the respective quadratic dual algebras.
Spontaneous Spin Polarization of Electrons by Diluted Magnetic Heterostructures  [PDF]
Chang Woo Lee, Amalorpavam John Peter
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.211157
Abstract: The spin dependent electron transmission phenomenon in a diluted resonant semiconductor heterostructure is employed theoretically to investigate the output transmission current polarization at zero magnetic field. Transparency of electron transmission is calculated as a function of electron energy and the well width, within the one electron band approximation along with the spin orbit interaction. Enhanced spin-polarized resonant tunneling in the heterostructure due to Dresselhaus and Rashba spin-orbit coupling induced splitting of the resonant level is observed. We predict that a spin-polarized current spontaneously emerges in this heterostructure and we estimate theoretically that the polarization can reach 40%. This effect could be employed in the fabrication of spin filters, spin injectors and detectors based on non-magnetic semiconductors.
Sensory Evaluation of Vegetable-Infused Fruit-Flavored Applesauce and the Comparison between Adults and Children  [PDF]
Peter Bordi, Kiwon Lee, Martha Conklin
Food and Nutrition Sciences (FNS) , 2013, DOI: 10.4236/fns.2013.45072

Low consumption of fruits and vegetables among children is considered to be a leading contributor to childhood obesity, making it prudent to develop healthier foods that are accessible, affordable and satisfying to children. Our objective was to investigate the sensory characteristics and preferred flavors of vegetable-infused applesauce among adults (male and female) and 7th grade middle school students; and to compare the flavor preferences of adults and children in order to gather information that helps determine target demographics for each applesauce flavor. Sensory testing for eight attributes (overall liking, overall appearance, appearance of texture, appearance of color, taste, mouth feel, amount of fruit flavor, amount of sweetness) were rated by 120 adults and 106 middle school students. Adults and kids demonstrated significantly different preferences for the tropical and mixed berry applesauce flavors but no difference with the strawberry banana-flavored applesauce. Female adults demonstrated clear preference for the strawberry banana flavor; children demonstrated a higher preference for the mixed berry flavor, followed by the tropical flavor. Overall, both adults and children rated all of the applesauce flavors favorably, suggesting that developing and bringing such products to market could be an effective method for helping adults and children consume more fruits and vegetables.

Systematic review of the epidemiological evidence comparing lung cancer risk in smokers of mentholated and unmentholated cigarettes
Peter N Lee
BMC Pulmonary Medicine , 2011, DOI: 10.1186/1471-2466-11-18
Abstract: Epidemiological studies comparing lung cancer risk in mentholated and non-mentholated cigarette smokers were identified from MedLine and other sources. Study details were extracted and strengths and weaknesses assessed. Relative risk estimates were extracted, or derived, for ever mentholated use and for long-term use, overall and by gender, race, and current/ever smoking, and meta-analyses conducted.Eight generally good quality studies were identified, with valid cases and controls, and appropriate adjustment for age, gender, race and smoking. The studies afforded good power to detect possible effects. However, only one study presented results by histological type, none adjusted for occupation or diet, and some provided no results by length of mentholated cigarette use.The data do not suggest any effect of mentholation on lung cancer risk. Adjusted relative risk estimates for ever use vary from 0.81 to 1.12, giving a combined estimate of 0.93 (95% confidence interval 0.84-1.02, n = 8), with no increase in males (1.01, 0.84-1.22, n = 5), females (0.80, 0.67-0.95, n = 5), White people (0.87, 0.75-1.03, n = 4) or Black people (0.90, 0.73-1.10, n = 4). Estimates for current and ever smokers are similar. The combined estimate for long-term use (0.95, 0.80-1.13, n = 4) again suggests no effect of mentholation.Higher lung cancer rates in Black males cannot be due to their greater preference for mentholated cigarettes. While some study weaknesses exist, the epidemiological evidence is consistent with mentholation having no effect on the lung carcinogenicity of cigarettes.According to Giovino et al. [1], who summarized evidence from over 50 countries, the market share of mentholated cigarettes is relatively high in the Philippines (60%), Cameroon (35-40%), Hong Kong (26%), the United States (26%) and Singapore (22%), though it is less than 5% in half the countries considered. They reported that, in the United States, Newport brands accounted for 29.7% of all menthol sales, w
Early diagnosis and treatment referral of children born small for gestational age without catch-up growth are critical for optimal growth outcomes
Peter Lee, Christopher Houk
International Journal of Pediatric Endocrinology , 2012, DOI: 10.1186/1687-9856-2012-11
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