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Wyszukujesz frazę "Sánchez, Roberto" wg kryterium: Autor


Wyświetlanie 1-5 z 5
Tytuł:
The Lucas congruence for Stirling numbers of the second kind
Autorzy:
Sánchez-Peregrino, Roberto
Powiązania:
https://bibliotekanauki.pl/articles/1207077.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Opis:
0. Introduction. The numbers introduced by Stirling in 1730 in his Methodus differentialis [11], subsequently called "Stirling numbers" of the first and second kind, are of the greatest utility in the calculus of finite differences, in number theory, in the summation of series, in the theory of algorithms, in the calculation of the Bernstein polynomials [9]. In this study, we demonstrate some properties of Stirling numbers of the second kind similar to those satisfied by binomial coefficients; in particular we show that they satisfy a congruence analogous to that of Lucas, that is to: $(a \atop b) ≡ ∏_{i=0}^{n} (a_{i} \atop b_{i}) mod p$ with $a = ∑_{i=0}^{n} a_{i} p^i$, $b = ∑_{i=0}^{n} b_{i} p^{i}$; $0 ≤ a_i ≤ p-1$, $0 ≤ b_i ≤ p-1$. Using Proposition 4.1 we give another proof for Kaneko's recurrence formula for poly-Bernoulli numbers [10]. Some of the results are similar to those of Howard [5].
In conclusion, I wish to give my best thanks to the Geometry Group of the Dipartimento di Matematica Pura ed Applicata and Dipartimento di Metodi Matematici per le Scienze Applicate of the University of Padova, for support and help given during the preparation of this work. In particular, I wish to thank Frank Sullivan for his precious advice and suggestions.
Źródło:
Acta Arithmetica; 2000, 94, 1; 41-52
0065-1036
Pojawia się w:
Acta Arithmetica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transmittance measurement of the in vivo human eye with a double-pass system
Autorzy:
Sánchez, Roberto
De Paul, Aníbal
Burgos-Fernández, Francisco
Vilaseca, Meritxell
Pujol, Jaume
Issolio, Luis
Powiązania:
https://bibliotekanauki.pl/articles/1835770.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
double-pass
transmittance
human eye
Opis:
Purpose: To develop a methodology based on a double-pass system to obtain information about the transmittance of ocular media. Methods: The procedure consists of recording double-pass images at different powers of a laser diode of 780 nm and determining the scattering in an area between 25–35 arcmin of each image. The scattering showed linear behavior in respect to the irradiance of the laser, and the slope of the linear fit was proportional to the transmittance squared of the media evaluated. An artificial eye with different filters was tested first. Then, fifteen subjects with clear ocular media were divided into two groups: ten subjects classified by the iris color were recruited for the measurements of an ocular transmittance index and the estimation of the transmittance (group A), and another five subjects were selected for measurements with neutral filters (group B). Results: The measurements performed in group A presented a mean transmittance of 42.95%. No differences in the transmittance were found between subjects with different iris color (p = 0.154). Measurements in group B showed a good correlation (r = 0.959, p < 0.001) between the expected and the measured value for the transmittance. Conclusion: We proposed and evaluated a method to determine the transmittance of the eye in vivo using the double-pass system.
Źródło:
Optica Applicata; 2021, 51, 1; 1-21
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Limitations of urban development in land of social origin: the case of the metropolitan area of the city of Toluca (ZMCT)
Autorzy:
Jiménez-Sánchez, Pedro Leobardo
Calderón-Maya, Juan Roberto
Campos-Alanís, Héctor
Powiązania:
https://bibliotekanauki.pl/articles/1035934.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Warszawski. Wydział Geografii i Studiów Regionalnych
Tematy:
Space
land
urban development
Toluca
Opis:
The paper analyses the occupation process of agricultural land with social origin and urban uses in the metropolitan area of the city of Toluca (ZMCT), and the barriers that the population and authorities have to face in order to regularize the settlements. A mixed research method was applied, which included the use of quantitative and qualitative methods, on the basis of a theoretical analysis, to build a methodological research model, which was applied to an empirical case in municipal and metropolitan areas. The analysis of the 14 municipalities that constitute ZMCT shows that the barriers for regularizing settlements in land of social origin are the result of legal/administrative inefficiencies due to the incapability of local city halls to address the collective needs of society.
Źródło:
Miscellanea Geographica. Regional Studies on Development; 2016, 20, 2; 19-24
0867-6046
2084-6118
Pojawia się w:
Miscellanea Geographica. Regional Studies on Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bond´s work index estimation using non-standard ball mills
Autorzy:
Arellano-Piña, Ramón
Sanchez-Ramirez, Elvia Angélica
Pérez-Garibay, Roberto
Gutiérrez-Pérez, V.H.
Powiązania:
https://bibliotekanauki.pl/articles/27323664.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Bond´s Work Index
rocks grinding
laboratory scale ball mills
ore characterization
non-standard ball mills
Opis:
Ore concentrators seek the stability of processes by feeding blends of rocks with average hardness and ore content. Therefore, large amounts of samples must be characterized in a short time. The Bond Work Index () is a common technique for the estimation of hardness and energy requirement for comminution using ball mills. However, this technique is time-consuming (close to 5 hours) and liable to experimental errors. This work contributes to obtaining new models for rapid Bond Work Index estimation using non-standard dimensions mills. This was done by proposing grinding tests using four types of ores and four mills of different dimensions, including the standard Bond ball mill (BBM). For all tests it was kept constant: (a) critical speed (91%), and (b) mill charge by volume (10.5%), varying the amount of fresh feed according to its density. The results showed that using the non-standard mills (between 20 and 35 cm in diameter), the Bond´s model constants (=0.23; = 0.82, and = 44.5), are unable to predict the Work Index properly. Therefore, these constants must be recalculated using linear models based on mill diameter. With the models proposed for , , and , the Bond Work Index (kWh/t) can be rapidly estimated (less than 2 hours) and show a high accuracy for mills of non-standard dimensions (R2= 0.96).
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 6; art. no. 172458
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
ASSESSMENTS OF ANTIOXIDANT CONTENT AND THE ANTI-CARCINOGENIC EFFECT OF EXTRACTS OF SOLANUM ROSTRATUM DUNAL IN HUMAN CANCER CELLS
Autorzy:
Valadez Vega, María del Carmen
Izquierdo Vega, Jeannett Alejandra
Villagómez Ibarra, Jose Roberto
Sánchez Gutiérrez, Manuel
Madrigal Santillán, Eduardo Osiris
Morales Gonzalez, Jose Antonio
Bautista Ávila, Mirandeli
García Velasco, Laura
Powiązania:
https://bibliotekanauki.pl/articles/895384.pdf
Data publikacji:
2019-06-28
Wydawca:
Polskie Towarzystwo Farmaceutyczne
Tematy:
antioxidant
cytotoxic
Solanum rostratum
SiHa cell line
MDA cell line
Opis:
In Mexico, Solanum rostratum has been employed for the treatment of several diseases, including uterine cancer. The aim of this study was to evaluate the antioxidant and anti-carcinogenic activity of extracts of Solanum rostratum Dunal on MDA and SiHa cell lines. The methanolic, ethyl acetate, and hexane extracts of the aerial parts of Solanum rostratum were tested for phenols concentration, antioxidant activity, and anti-carcinogenic effect. The leaves extracts showed the highest content of phenols; however the flower-fruits extracts showed higher scavenging activity. On the other hand, ethyl acetate extracts exhibited the highest anti-carcinogenic effect, while methanolic extracts showed the least effect. The results of this work indicated that Solanum rostratum is a promising source of antioxidants, and the extracts exert a dose-dependent anti-carcinogenic effect on both cell lines.
Źródło:
Acta Poloniae Pharmaceutica - Drug Research; 2019, 76, 3; 493-502
0001-6837
2353-5288
Pojawia się w:
Acta Poloniae Pharmaceutica - Drug Research
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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