Analytical viewpoint. New time-invariant definition of Analytical Chemistry aimed at improving the scope of Analytical Abstracts

1993 ◽  
Vol 30 (5) ◽  
pp. 216 ◽  
Author(s):  
Tibor Braun
Keyword(s):  
Analytical Chemistry ◽  
Definition Of ◽  
Time Invariant ◽  
Invariant Definition ◽  
New Time

scholarly journals António Ferreira da Silva and the Teaching of Chemistry at the Academia Politécnica do Porto (1877–1910)

2019 ◽  
Vol 20 ◽  
pp. 213-221 ◽  
Author(s):  
José Ferraz-Caetano ◽  
João Paiva ◽  
Francisco Malta Romeiras
Keyword(s):  
Public Health ◽  
Analytical Chemistry ◽  
Nineteenth Century ◽  
Health Education ◽  
Crucial Role ◽  
Public Health Education ◽  
Scientific Education ◽  
Definition Of ◽  
Practical Teaching

Resumo No final do século XIX, a química ganhou notoriedade como uma das principais “ciências ao serviço” da nação. O surgimento de novos tópicos, métodos e práticas úteis contribuíram para a valorização da química e para a definição de medidas governamentais em temas como saúde pública, educação e proteção ambiental. Lente na Academia Politécnica do Porto entre 1877 e 1910, António Ferreira da Silva (1853–1923) desempenhou um papel central na modernização do ensino e da investigação em química em Portugal. Ferreira da Silva foi responsável pela introdução de cursos suplementares de química, pela reformulação do ensino prático, e pela elaboração de novos procedimentos e regulamentos de ensino “que em muito engrandeceram a educação científica” em Portugal. Enquanto lente da Academia Politécnica do Porto, Ferreira da Silva privilegiou ainda a articulação entre o Laboratório da Academia e as indústrias nacionais, contribuindo, em larga medida, para emergência da Química Analítica como uma nova disciplina.Palavras-chave: António Ferreira da Silva; Academia Politécnica do Porto; Química Analítica. Abstract By the turn of the nineteenth century, chemistry had become a “science at the service” of the nation. The emergence of useful topics, methods, and practices contributed to the valorization of chemistry and to the definition of new governmental directives on issues such as public health, education and environment. Lecturer at the Academia Politécnica do Porto between 1877 and 1911, António Ferreira da Silva (1853–1923) played a crucial role in the modernization of the teaching and practice of chemistry in Portugal. Ferreira da Silva created new supplementary chemistry courses, reformed the practical teaching of chemistry, and drafted new proceedings and syllabi “that glorified scientific education” in Portugal. As lecturer of the Academia Politécnica do Porto, he made important steps in the establishment of collaborations between the Academia’s Laboratory and national industries, which largely contributed to the emergence of Analytical Chemistry as an autonomous discipline. Keywords: António Ferreira da Silva; Academia Politécnica do Porto; Analytical Chemistry.

Deterministic Continuous-Time Signals and Systems

2021 ◽  
pp. 562-598
Author(s):  
Stevan Berber
Keyword(s):  
Discrete Time ◽  
Continuous Time ◽  
Linear Time ◽  
Continuous Variable ◽  
Linear Time Invariant ◽  
Time Signals ◽  
Analysis And Synthesis ◽  
Linear Time Invariant Systems ◽  
Definition Of ◽  
Time Invariant

Due to the importance of the concept of independent variable modification, the definition of linear-time-invariant system, and their implications for discrete-time signal processing, Chapter 11 presents basic deterministic continuous-time signals and systems. These signals, expressed in the form of functions and functionals such as the Dirac delta function, are used throughout the book for deterministic and stochastic signal analysis, in both the continuous-time and the discrete-time domains. The definition of the autocorrelation function, and an explanation of the convolution procedure in linear-time-invariant systems, are presented in detail, due to their importance in communication systems analysis and synthesis. A linear modification of the independent continuous variable is presented for specific cases, like time shift, time reversal, and time and amplitude scaling.

Selectivity in analytical chemistry (IUPAC Recommendations 2001)

2001 ◽  
Vol 73 (8) ◽  
pp. 1381-1386 ◽  
Author(s):  
Jörgen Vessman ◽  
Raluca I. Stefan ◽  
Jacobus F. van Staden ◽  
Klaus Danzer ◽  
Wolfgang Lindner ◽  
...  
Keyword(s):  
Analytical Chemistry ◽  
Clear Distinction ◽  
Definition Of

The correct use of the term "selectivity" and its clear distinction from the term "specificity" are discussed. A definition of selectivity is given, and it is recommended that the use of this term be promoted and that the use of the term "specificity" be discouraged.

scholarly journals Gauge invariant definition of the jet quenching parameter

2013 ◽  
Vol 2013 (2) ◽  
Author(s):  
Michael Benzke ◽  
Nora Brambilla ◽  
Miguel A. Escobedo ◽  
Antonio Vairo
Keyword(s):  
Jet Quenching ◽  
Gauge Invariant ◽  
Definition Of ◽  
Invariant Definition

scholarly journals Wine adulteration and its detection based on the rate and the concentration of free amino acids

2018 ◽  
pp. 139-151
Author(s):  
János Csapó ◽  
Csilla Albert
Keyword(s):  
Analytical Chemistry ◽  
Amino Acids ◽  
Free Amino ◽  
High Performance ◽  
Amino Acid Content ◽  
Review Article ◽  
Point Of View ◽  
Free Amino Acid Content ◽  
Ancient Times ◽  
Definition Of

Following the definition of wine adulteration, the authors briefly review its history from ancient times to present day and describe the methods that are applied for adulteration of wine from the historical point of view. More space is devoted to the Hungarian wine adulteration and to the detailed reports of the early methods, which attempted to discover fake wine. It describes in detail the current situation of wine adulteration and the fight against counterfeiting. The second half of the review article presents some examples of the analytical chemistry techniques with which fake wines can be detected. In doing so, priority is given to the discussion of high performance liquid chromatography and gas chromatography applications. The end of this paper describes the free amino acid content of wines, and the possibilities of using the results for detection of wine adulteration.

Deterministic Discrete-Time Signals and Systems

2021 ◽  
pp. 690-713
Author(s):  
Stevan Berber
Keyword(s):  
Discrete Time ◽  
Communication Systems ◽  
Linear Time ◽  
Linear Time Invariant ◽  
Discrete Signals ◽  
Time Signals ◽  
Analysis And Synthesis ◽  
Linear Time Invariant Systems ◽  
Definition Of ◽  
Time Invariant

Due to the importance of the concept of independent discrete variable modification and the definition of discrete linear-time-invariant systems, Chapter 14 presents and discusses basic deterministic discrete-time signals and systems. These discrete signals, which are expressed in the form of functions, including the Kronecker delta function and the discrete rectangular pulse, are used throughout the book for deterministic discrete signal analysis. The chapter also presents the definition of the autocorrelation function and the explanation of the convolution procedure in linear-time-invariant systems for discrete-time signals in detail, due to the importance of these in the analysis and synthesis of discrete communication systems.

scholarly journals Have precipitation extremes and annual totals been increasing in the world's dry regions over the last 60 years?

2017 ◽  
Vol 21 (1) ◽  
pp. 441-458 ◽  
Author(s):  
Sebastian Sippel ◽  
Jakob Zscheischler ◽  
Martin Heimann ◽  
Holger Lange ◽  
Miguel D. Mahecha ◽  
...  
Keyword(s):  
Precipitation Extremes ◽  
Positive Trend ◽  
Specific Data ◽  
Global Trend ◽  
Precipitation Characteristics ◽  
Highly Sensitive ◽  
Definition Of ◽  
Time Invariant ◽  
Theoretical Considerations

Abstract. Daily precipitation extremes and annual totals have increased in large parts of the global land area over the past decades. These observations are consistent with theoretical considerations of a warming climate. However, until recently these trends have not been shown to consistently affect dry regions over land. A recent study, published by Donat et al. (2016), now identified significant increases in annual-maximum daily extreme precipitation (Rx1d) and annual precipitation totals (PRCPTOT) in dry regions. Here, we revisit the applied methods and explore the sensitivity of changes in precipitation extremes and annual totals to alternative choices of defining a dry region (i.e. in terms of aridity as opposed to precipitation characteristics alone). We find that (a) statistical artifacts introduced by data pre-processing based on a time-invariant reference period lead to an overestimation of the reported trends by up to 40 %, and that (b) the reported trends of globally aggregated extremes and annual totals are highly sensitive to the definition of a dry region of the globe. For example, using the same observational dataset, accounting for the statistical artifacts, and based on different aridity-based dryness definitions, we find a reduction in the positive trend of Rx1d from the originally reported +1.6 % decade−1 to +0.2 to +0.9 % decade−1 (period changes for 1981–2010 averages relative to 1951–1980 are reduced to −1.32 to +0.97 % as opposed to +4.85 % in the original study). If we include additional but less homogenized data to cover larger regions, the global trend increases slightly (Rx1d: +0.4 to +1.1 % decade−1), and in this case we can indeed confirm (partly) significant increases in Rx1d. However, these globally aggregated estimates remain uncertain as considerable gaps in long-term observations in the Earth's arid and semi-arid regions remain. In summary, adequate data pre-processing and accounting for uncertainties regarding the definition of dryness are crucial to the quantification of spatially aggregated trends in precipitation extremes in the world's dry regions. In view of the high relevance of the question to many potentially affected stakeholders, we call for a well-reflected choice of specific data processing methods and the inclusion of alternative dryness definitions to guarantee that communicated results related to climate change be robust.

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