scholarly journals Interpretación didáctica de la teoría de grupos aplicada en cristales

Respuestas ◽  
2018 ◽  
Vol 23 (1) ◽  
pp. 68
Author(s):  
V. H. Sierra ◽  
C. A. Aguirre ◽  
José José Barba-Ortega

ResumenLa determinación del Hamiltoniano de una molécula o un cristal puede llegar a ser un problema muy complicado; sin embargo, las consideraciones de simetría sobre el problema pueden llegar a simplificarlo de manera sustancial. Razón por la cual, es pertinente buscar el mayor número de simetrías de un cristal. En este punto, se realza la importancia de la teoría de grupos como herramienta de cálculo, pues a través de ésta, se sintetizan todas las propiedades del cristal: las rotaciones, las inversiones y las reflexiones. Empero, el estudio realizado por muchos libros acerca de esta temática es demasiado confuso y complicado para los estudiantes de Licenciatura en Física, debido a la naturaleza abstracta del método de la teoría, y las relaciones que éste tiene con el Hamiltoniano. Lo anterior, motiva la realización de un estudio didáctico, así como detallado de los principios que rigen el uso del método. Además, se ilustra a través de un ejemplo detallado para el caso de un cristal ortorrómbico, procediendo a establecer los isomorfismos entre el álgebra utilizada en la teoría de grupos y la correspondiente representación de matrices, que permita efectuar la reducción del Hamiltoniano y los cálculos correspondientes.Palabras clave: Simetría, Hamiltoniano, Teoría de grupos.AbstractThe determination of the Hamiltonian of a molecule or a crystal can become a very complicated problem. However, considerations of symmetry of the problem may make it simpler. Therefore it is relevant seek the greatest number of symmetries of a crystal. At this point, it highlights the                importance of group theory as a tool for calculation, then, through it synthesizes all of these properties of the crystal, like the rotations, inversions and reflections. However, the study present in many books on this subject is too confusing and complicated for the students of Bachelor in Physics,  because of the abstract nature of theoretical method and the relationship it has with the Hamiltonian. This one motivates the realization of a didactic study, as well as detailed principles governing the use of the method. Also, a detailed example is present for the case of an orthorhombic crystal, proceeding to establish the isomorphism between the algebra used in group theory and the corresponding matrix representation, permitting a reduction in the Hamiltonian and the calculations.Keywords: Symmetry, Hamiltonian, Group TheoryResumoA determinação do Hamiltoniano de uma molécula ou cristal pode se tornar um problema muito complicado; No entanto, considerações de simetria sobre o problema podem simplificá-lo            substancialmente. Pelo que, é pertinente procurar o maior número de simetrias de um cristal. Nesse ponto, enfatiza-se a importância da teoria dos grupos como ferramenta de cálculo, pois através dela todas as propriedades do cristal são sintetizadas: rotações, inversões e reflexões. No entanto, o estudo de muitos livros sobre este assunto é muito confuso e complicado para os estudantes de graduação em Física, por causa da natureza abstrata do método da teoria, e a relação que tem com o  hamiltoniano. O exposto, motiva a realização de um estudo didático, bem como detalha os princípios que regem o uso do método. Além disso, é ilustrada através de um processo detalhado de um cristal ortorrômbico, prosseguir para estabelecer a isomorfismo entre álgebra utilizado na teoria de grupos e a representação correspondente de matrizes, permitindo a redução do exemplo Hamiltoniano e cálculos.Palabras chave: Simetria, hamiltoniana, teoria dos grupos

1994 ◽  
Vol 72 (03) ◽  
pp. 426-429 ◽  
Author(s):  
S Kitchen ◽  
I D Walker ◽  
T A L Woods ◽  
F E Preston

SummaryWhen the International Normalised Ratio (INR) is used for control of oral anticoagulant therapy the same result should be obtained irrespective of the laboratory reagent used. However, in the UK National External Quality Assessment Scheme (NEQAS) for Blood Coagulation INRs determined using different reagents have been significantly different.For 18 NEQAS samples Manchester Reagent (MR) was associated with significantly lower INRs than those obtained using Diagen Activated (DA, p = 0.0004) or Instrumentation Laboratory PT-Fib HS (IL, p = 0.0001). Mean INRs for this group were 3.15, 3.61, and 3.65 for MR, DA, and IL respectively. For 61 fresh samples from warfarin-ised patients with INRs of greater than 3.0 the relationship between thromboplastins in respect of INR was similar to that observed for NEQAS data. Thus INRs obtained with MR were significantly lower than with DA or IL (p <0.0001). Mean INRs for this group were 4.01, 4.40, and 4.59 for MR, DA, and IL respectively.We conclude that the differences between INRs measured with the thromboplastins studied here are sufficiently great to influence patient management through warfarin dosage schedules, particularly in the upper therapeutic range of INR. There is clearly a need to address the issues responsible for the observed discrepancies.


2016 ◽  
pp. 137-142
Author(s):  
V.O. Benyuk ◽  
◽  
V.M. Goncharenko ◽  
T.R. Nykoniuk ◽  
◽  
...  

The objective: to еxplore the relationship between the activity of endometrial proliferation and the state of the local immune response in the uterus in the conditions berprestasi process. Patients and methods. Examined 228 women of reproductive and perimenopausal age with endometrial pathology using ultrasound and then performing hysteroresectoscopy. Determination of the concentrations of the cytokines IL-1, IL-2, IL-6 and TNF was performed by solid phase ELISA. Results. Found a trend that confirms the loss of sensitivity to hormones at the stage of malignancy of the endometrium and can be used as diagnostic determinants in determining the nature of intrauterine pathology and criterion of the effectiveness of conservative therapy. Conclusion. Improving etiopatogenetice approach to the therapy of hyperplastic proce.sses of endometrium with determination of receptor phenotype of the endometrium is a research direction in modern gynecology, which will help to improve the results of treatment and prevention of intrauterine pathology. Key words: endometrial hyperplasia,the receptors for progesterone and estrogen, immunohistochemical method.


2012 ◽  
Vol 34 (3) ◽  
pp. 169-184 ◽  
Author(s):  
Hoang Thi Bich Ngoc

Vertical axis wind turbine technology has been applied last years, very long after horizontal axis wind turbine technology. Aerodynamic problems of vertical axis wind machines are discussible. An important problem is the determination of the incidence law in the interaction between wind and rotor blades. The focus of the work is to establish equations of the incidence depending on the blade azimuth, and to solve them. From these results, aerodynamic torques and power can be calculated. The incidence angle is a parameter of velocity triangle, and both the factors depend not only on the blade azimuth but also on the ratio of rotational speed and horizontal speed. The built computational program allows theoretically selecting the relationship of geometric parameters of wind turbine in accordance with requirements on power, wind speed and installation conditions.


1986 ◽  
Vol 14 (4) ◽  
pp. 201-218 ◽  
Author(s):  
A. G. Veith

Abstract This four-part series of papers addresses the problem of systematic determination of the influence of several tire factors on tire treadwear. Both the main effect of each factor and some of their interactive effects are included. The program was also structured to evaluate the influence of some external-to-tire conditions on the relationship of tire factors to treadwear. Part I describes the experimental design used to evaluate the effects on treadwear of generic tire type, aspect ratio, tread pattern (groove or void level), type of pattern (straight rib or block), and tread compound. Construction procedures and precautions used to obtain a valid and functional test method are included. Two guiding principles to be used in the data analyses of Parts II and III are discussed. These are the fractional groove and void concept, to characterize tread pattern geometry, and a demonstration of the equivalence of wear rate for identical compounds on whole tread or multi-section tread tires.


2017 ◽  
Vol 3 (1) ◽  
pp. 42
Author(s):  
Roshanira Che Mohd Noor ◽  
Nur Atiqah Rochin Demong

Providing a safe and healthy workplace is one of the most effective strategies in for holding down the cost of doing construction business. It was a part of the overall management system to facilitate themanagement of the occupational health and safety risk that are associated with the business of the organization. Factors affected the awareness level inclusive of safety and health conditions, dangerous working area, long wait care and services and lack of emergency communication werethe contributed factors to the awareness level for the operational level. Total of 122 incidents happened at Telekom Malaysia Berhad as compared to year 2015 only 86 cases. Thus, the main objective of this study was to determine the relationship between safety and health factors and the awareness level among operational workers.The determination of this research was to increase the awareness level among the operational level workerswho committing to safety and health environment.


2013 ◽  
pp. 11-17
Author(s):  
Thi Tuy Ha Nguyen ◽  
Thi Minh Thi Ha

Background: The role of p53 gene in the gastric cancer is still controversial. This study is aimed at determining the rate of the p53 gene codon 72 polymorphisms in gastric cancer patients and evaluating the relationship between these polymorphisms and endoscopic and histopathological features of gastric cancer. Patients and methods: Sixty eight patients with gastric cancer (cases) and one hundred and thirty six patients without gastric cancer (controls) were enrolled. p53 gene codon 72 polymorphisms were determined by PCR-RFLP technique with DNA extracted from samples of gastric tissue. Results: In the group of gastric cancer, Arginine/Argnine, Arginine/Proline and Proline/Proline genotypes were found in 29.4%, 42.7% and 27.9%, respectively. The differences of rates were not statistically significant between cases and controls (p > 0,05). In males, the Proline/Proline genotype was found in 38.1% in patients with gastric cancer and more frequent in patients without gastric cancer (15.7%, p = 0,01). An analysis of ROC curve showed that the cut-off was the age of 52 in the Proline/Proline genotype, but it was 65 years old in the Arginine/Proline genotype. The Proline/Proline genotype was found in 41.9% in Borrmann III/IV gastric cancer, this rate was higher than Borrmann I/II gastric cancer (16.2%, p = 0.037) and also higher than controls (18.4%, p = 0,01). The rate of Proline/Proline genotype was 41.7% in the diffuse gastric cancer, it was higher than in controls (p = 0,023). Conclusion: No significative difference of rate was found in genotypes between gastric cancer group and controls. However, there was the relationship between Proline/Proline genotype and gastric cancer in males, Borrmann types of gastric cancer, the diffuse gastric cancer. Key words: polymorphism, codon 72, p53 gene, PCR - RFLP, gastric cancer.


1995 ◽  
Vol 31 (11) ◽  
pp. 153-158 ◽  
Author(s):  
M. Kajino ◽  
K. Sakamoto

Musty odor has occurred annually in Lake Biwa since 1969. Osaka municipal waterworks, which is located downstream of Lake Biwa, has made many efforts to treat musty-odor compounds produced in Lake Biwa from spring through autumn. With the development of analytical methods for the determination of musty-odor compounds, we have been able to confirm that planktonic blue-green algae are the major causes of the musty-odor occurrences. The relationship between the growth of blue-green algae and the water quality was not so apparent. However, through our data analysis focusing on the relationship between musty-odor occurrences due to Phormidium tenue or Oscillatoria tenuis and some nutrients in Lake Biwa, we found that the concentration of nitrate in water may be an important parameter for the estimation of growth of the algae and the musty-odor behavior.


Author(s):  
Daniel Clarry

This chapter discusses the nature and operation of mandatory and default rules in fiduciary law, arguing that loyalty is a core element of every fiduciary legal institution. Loyalty is the hallmark of fiduciary law, as it requires persons in other-regarding positions of power to perform functions selflessly, rather than selfishly. However, there are many circumstances in which a person undertakes and exercises other-regarding powers, underscoring the fact that a broad range of persons may be the subject of fiduciary law. This chapter first provides an overview of key concepts and context, focusing on the distinction between mandatory rules and default rules as well as sources of such rules in fiduciary law. It then considers fiduciary loyalty, citing examples that illustrate how a baseline of fiduciary accountability is implied by the essential nature of fiduciary legal institutions, along with the mandatory or default quality of the duties of care and good faith. The main thesis of this chapter is that loyalty is a basic constituent element of all fiduciary legal institutions. Whether fiduciary principles are mandatory involves a consideration and determination of whether the relationship or institution is inherently fiduciary as matter of law and legal classification. It also highlights the modern trend toward codification and clear legislative demarcation of mandatory and default rules in fiduciary law.


2015 ◽  
Vol 72 (2) ◽  
pp. 123-131 ◽  
Author(s):  
Marko Igic ◽  
Nebojsa Krunic ◽  
Ljiljana Aleksov ◽  
Milena Kostic ◽  
Aleksandra Igic ◽  
...  

Background/Aim. The vertical dimension of occlusion is a very important parameter for proper reconstruction of the relationship between the jaws. The literature describes many methods for its finding, from the simple, easily applicable clinically, to quite complicated, with the use of one or more devices for determination. The aim of this study was to examine the possibility of determining the vertical dimension of occlusion using the vocals ?O? and ?E? with the control of values o btained by applying cognitive functions. Methods. This investigation was performed with the two groups of patients. The first group consisted of 50 females and 50 males, aged 18 to 30 years. In this group the distance between the reference points (on top of the nose and chin) was measured in the position of the mandible in the vertical dimension of occlusion, the vertical dimension at rest and the pronunciation of the words ?OLO? and ?ELE?. Checking the correctness of the particular value for the word ?OLO? was also performed by the phonetic method with the application of cognitive exercises when the patients counted from 89 to 80. The obtained difference in the average values i n determining the vertical dimension of occlusion and the ?OLO? and ?ELE? in the first group was used as the reference for determining the vertical dimension of occlusion in the second group of patients. The second group comprised of 31 edentulous persons (14 females and 17 males), aged from 54 to 85 years who had been made a complete denture. Results. The average value obtained for the vertical dimension of rest for the entire sample was 2.16 mm, for the word ?OLO? for the entire sample was 5.51 mm and for the word ?ELE? for the entire sample was 7.47 mm. There was no statistically significant difference between the genders for the value of the vertical dimension at rest, ?ELE? and ?OLO?. There was a statistically significant difference between the values f or the vertical dimension at rest, ?OLO? and ?ELE? for both genders. There was a statistically significant correlation between the value for the vertical dimension at rest, ?OLO? and ?ELE?, for both groups of subjects. Conclusion. Determining the vertical dimension of occlusion requires 5.5 mm subtraction from the position of the mandible in pronunciation of the word ?OLO? or 7.5 mm in pronunciation of the word ?ELE?.


Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4002
Author(s):  
Anamaria Iulia Török ◽  
Ana Moldovan ◽  
Erika Andrea Levei ◽  
Oana Cadar ◽  
Claudiu Tănăselia ◽  
...  

Lithium is a critical element for the modern society due to its uses in various industrial sectors. Despite its unequal distribution in the environment, Li occurrence in Romania was scarcely studied. In this study a versatile measurement method using ICP-MS technique was optimized for the determination of Li from various matrixes. Water, soil, and plant samples were collected from two important karst areas in the Dobrogea and Banat regions, Romania. The Li content was analyzed together with other macro- and microelement contents to find the relationship between the concentration of elements and their effect on the plants’ Li uptake. In Dobrogea region, half of the studied waters had high Li concentration, ranging between 3.00 and 12.2 μg/L in the case of water and between 0.88 and 11.1 mg/kg DW in the case of plants, while the Li content in the soil samples were slightly comparable (from 9.85 to 11.3 mg/kg DW). In the Banat region, the concentration of Li was lower than in Dobrogea (1.40–1.46 μg/L in water, 6.50–9.12 mg/kg DW in soil, and 0.19–0.45 mg/kg DW in plants). Despite the high Li contents in soil, the Li was mostly unavailable for plants uptake and bioaccumulation.


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