On the Calculation of Pair Creation by Fast Charged Particles and the Effect of Screening

1935 ◽  
Vol 31 (3) ◽  
pp. 394-406 ◽  
Author(s):  
H. J. Bhabha
Keyword(s):  
Impact Parameter ◽  
Momentum Space ◽  
Minimum Distance ◽  
Rest Mass ◽  
Charged Particles ◽  
The Other ◽  
Initial State ◽  
Special Cases ◽  
The Creation ◽  
The Impact

In a recent paper I developed a method for calculating the probability of the creation of an electron pair in the collision of two charged particles moving with a relative velocity very near that of light. I showed there that under certain conditions it is legitimate to treat one of the colliding particles, say the heavier one of charge Z2 and rest mass M2, which we shall call the particle 2, as fixed at the origin of coordinates, and the other, of charge Z1 and rest mass M1, which we shall call the particle 1, as moving classically along a straight line with uniform velocity V in the direction of the z-axis, passing the other particle 2 at a minimum distance of approach (impact parameter) b. I developed expressions (given by (18) to (22) of A) giving the probability of the transition of an electron from an initial state of negative energy E0 and momentum p0 lying in an element of momentum space dp0 to a final state of energy E and momentum p lying in an element of momentum space dp, under the combined perturbing influence of the two colliding particles when they pass at a minimum distance b. The initial state of the electron, left vacant after the transition, appears as a positron of momentum p+ = − p0. To get the differential effective cross-section for the creation of the above pair, we must integrate this probability over all values of the impact parameter b, and this integration can be performed easily as shown in A. The final result can be written as a sum of a finite number of doubly infinite integrals (A, (24)). The purpose of this paper is to carry through the evaluation of these integrals for certain special cases, and to consider the effects of screening. The results have already been communicated in A.

The multiplicity characteristics of 7Li-Em interactions as a function of noninteracting projectile nucleons

2020 ◽  
Vol 29 (08) ◽  
pp. 2050063
Author(s):  
M. Mohery ◽  
E. M. Sultan ◽  
N. N. Abdallah ◽  
M. H. Farghaly
Keyword(s):  
Impact Parameter ◽  
Charged Particles ◽  
Heavy Ion ◽  
The Other ◽  
Total Charge ◽  
Secondary Particles ◽  
Ion Interactions ◽  
Charged Secondary ◽  
The Impact ◽  
Relativistic Particles

In this work, the interactions of 7Li nuclei with emulsion at 3 A GeV/c were studied. Multiplicity of the charged secondary particles as well as the charge of the outgoing projectile fragments were measured, while correlations among them are discussed. The values of the total charge of the noninteracting projectile nucleons and the average number of interacting projectile nucleons are estimated. The dependence of the secondary particles on the number of heavily-ionized tracks is analyzed. The results show that interactions of 7Li nuclei with emulsion nuclei exhibit a number of regularities, which had been noted in experiments with lighter nuclei. The absorption of relativistic particles, while increasing the degree of target destruction, is observed. The average multiplicities of the secondary charged particles depend on the impact parameter, as their values increase, while decreasing the impact parameter. The number of secondary charged particles in the heavy-ion interactions depends on the degree of disintegration of the target nuclei. This dependence is not observed in the case of the interaction of hadron with emulsion. The experimental data of the interaction of 7Li are systematically compared with the other interactions at different energies. The results agree with the corresponding results at nearly the same energy.

scholarly journals The emergence of environmental stewardship as a primary institution of global international society

2017 ◽  
Vol 25 (1) ◽  
pp. 131-155 ◽  
Author(s):  
Robert Falkner ◽  
Barry Buzan
Keyword(s):  
International Society ◽  
Environmental Stewardship ◽  
The Other ◽  
English School ◽  
The Creation ◽  
Normative Order ◽  
Primary Institutions ◽  
The Impact

This article develops an English School framework for analysing the emergence of new primary institutions in global international society, and applies this to the case of environmental stewardship. The article traces the impact that global environmentalism has had on the normative order of global international society, examines the creation of secondary institutions around this norm and identifies the ways in which these developments have become embedded in the constitution and behaviour of states. It assesses the ways in which environmental stewardship has interacted with the other primary institutions that compose global international society, changing some of the understandings and practices associated with them. The conclusions argue that environmental stewardship is likely to be a durable institution of global international society, and that it might be a harbinger of a more functional turn in its priorities.

STUDY OF FORWARD–BACKWARD SHOWER PARTICLE AND SLOW PROTON PRODUCTION FROM THE INTERACTIONS OF 7Li WITH EMULSION NUCLEI AT 3 A GeV/c

2002 ◽  
Vol 11 (02) ◽  
pp. 105-117 ◽  
Author(s):  
N. N. ABD-ALLAH
Keyword(s):  
Impact Parameter ◽  
Mass Number ◽  
Charged Particles ◽  
Parameter Dependence ◽  
Shower Particle ◽  
Experimental Factor ◽  
Proton Production ◽  
Correlation Strength ◽  
The Impact

The correlations between the multiplicities of secondary charged particles emitted in collisions of 3 A GeV/c 7 Li with emulsion have been studied. The dependence of the correlation strength on the mass number of the projectile has been analyzed. Moreover, the dependence of the average multiplicities of shower particle emitted in the forward and backward hemispheres on the number of target fragments has been investigated. The study of the number of backward slow protons (black and grey particles) indicates that, while the number of backward particles is a good factor representing the purely target fragments, the number of backward grey particles can be considered an accurate experimental factor for the impact parameter dependence of the collision.

scholarly journals The use of the term ‘limnology’ and its scientometrics consequences for limnologists

2021 ◽  
Author(s):  
Diego Fontaneto ◽  
Alejandro Martínez ◽  
Stefano Mammola ◽  
Aldo Marchetto
Keyword(s):  
Publication Output ◽  
Scientific Communication ◽  
The Other ◽  
Scientific Impact ◽  
Lake Ecology ◽  
The Creation ◽  
The Impact ◽  
Do So ◽  
The Way

Jargon is the specialised vocabulary of any science: it allows the creation of new terms to define concepts and it removes ambiguity from scientific communication. Yet, it may also hinder understanding for a broader audience. Given that the Journal of Limnology has jargon in its title, we here investigate the impact of the term ‘limnology’ on the way limnologists work, publish their research, and attract the interest of other scientists. We do so by comparing scientometric features of papers published from 1965 to 2020 that used the term ‘limnology’ against papers on similar topics but that used the term ‘lake ecology’ or ‘hydrobiology’, and to the marine counterpart of papers that used the term ‘oceanography’. We found that papers using the term limnology score worse than those of the other topics in terms of both publication output and scientific impact. Limnologists may need to use other terms in addition to ‘limnology’ to reach a broader scientific audience.

Cooperative mechanisms for the H + ICl reaction and their significance for the K + ICl experiment

1994 ◽  
Vol 72 (3) ◽  
pp. 919-927
Author(s):  
Antonio Laganà ◽  
Osvaldo Gervasi ◽  
Stefano Crocchianti ◽  
Ernesto Garcia ◽  
Guillermo Ochoa De Aspuru ◽  
...  
Keyword(s):  
Impact Parameter ◽  
The Other ◽  
The Impact

To characterize the dynamics of halogen centre reactions, we have investigated the H + ICl system. In particular, we have focused our attention on the importance of indirect atom–diatom reactivity in determining the macroscopic and microscopic branching of a reaction. An analysis of opacity functions and trajectory plots evaluated for different collision angles and isotopic variants evidenced the occurrence of cooperative reactive mechanisms in which an atom of the target diatom favours reaction with the other end of the molecule. Two limiting cooperative mechanisms were singled out and associated with different ranges of the impact parameter. A generalization of these findings to heavier systems has been performed by considering the 39H + ICl reaction. Calculated properties of the model were found to agree with values measured for the K + ICl reaction.

scholarly journals Technical solutions for working elements of machines for efficient compaction of soil

2018 ◽  
Vol 230 ◽  
pp. 01006
Author(s):  
Kazimir Glavatsky ◽  
Volodymyr Cherkudinov ◽  
Olexandr Posmitiuha
Keyword(s):  
Soil Compaction ◽  
Structural Elements ◽  
Initial State ◽  
Modular Units ◽  
Wide Range ◽  
Combined Action ◽  
The Creation ◽  
Technical Solutions ◽  
The Impact ◽  
Light Medium

The modernization of machines for compaction of soil on a modular basis has the following advantages: some of their structural elements (working equipment and working elements) can be performed as unified modular units, from which, depending on the technological requirements, it is possible to assemble the required configuration of the sealing machine; the initial state of the machine does not deteriorate, to which it is easy to return; the nomenclature of structural elements and machines in general decreases, as the machine can be completed with variable modules, which leads to an improvement in their quality. When consolidating the soil massive use static, dynamic and combined action on the soil in the form of rollers, vibro-and ramboards. Machines of the boottype are classified into light, medium and heavy, which determines the order of its application. It is obvious that the reduction of technology for the process of soil compaction is possible due to the creation of machines that can change the intensity of the impact on the soil in a wide range.

scholarly journals A Study on Managers' Creation of Budgetary Slack in Emerging Economies: The Case of Vietnam

2017 ◽  
Vol 2 (2) ◽  
pp. 15-28
Author(s):  
Quang-Huy Ngo ◽  
Thi-Nam-Ninh Doan ◽  
Thanh-Nha Huynh
Keyword(s):  
Information Asymmetry ◽  
Emerging Economies ◽  
The Other ◽  
Budgetary Slack ◽  
Future Studies ◽  
Developed Economies ◽  
Budgetary Participation ◽  
The Creation ◽  
The Impact ◽  
Insight Into

Although the budgeting literature well documents managers' creation of budgetary slack in developed economies, lack of attention has been paid to this behaviour in emerging economies. It is doubtful that some unique characteristics, only existing in emerging economies, cause this behaviour to be different than the budgeting literature predicts. Since there is no study examining managers' creation of budgetary slack in emerging economies, such as Vietnam, to get insight into whether or not these characteristics cause the differences, the aim of this study is to replicate prior budgeting studies by using Vietnamese samples. Particularly, we investigated the impact of budgetary participation, budget emphasis, information asymmetry, and the interactions between these variables on managers' creation of budgetary slack. Data obtained from the questionnaire sent to 99 Vietnamese managers shows that the last two variables and the interaction between them induce managers' creation of budgetary slack. However, the results also indicate that the first variable and the interaction between this variable and the other two variables respectively have no impact on managers' creation of budgetary slack. These results provide some insight into the creation of budgetary slack of Vietnamese managers for future studies to extend the line of research.

Supporting Requirements to Code Traceability Creation by Code Comments

2021 ◽  
Vol 31 (08) ◽  
pp. 1099-1118
Author(s):  
Guohua Shen ◽  
Haijuan Wang ◽  
Zhiqiu Huang ◽  
YaoShen Yu ◽  
Kai Chen
Keyword(s):  
Empirical Study ◽  
Software Maintenance ◽  
Source Code ◽  
The Other ◽  
Different Types ◽  
The Creation ◽  
The Impact ◽  
Code Tracing

Requirements-to-code tracing is an important and costly task that creates trace links from requirements to source code. These trace links help engineers reduce the time and complexity of software maintenance. Code comments play an important role in software maintenance tasks. However, few studies have focused intensively on the impact of code comments on requirements-to-code trace links creation. Different types of comments have different purposes, so how different types of code comments provide different improvements for requirements-to-code trace links creation? We focus on learning whether code comments and different types of comments can improve the quality of trace links creation. This paper presents a study to evaluate the contribution of code comments and different types of code comments to the creation of trace links. More specifically, this paper first experimentally evaluates the impact of code comments on requirements-to-code trace links creation, and then divides code comments into six categories to evaluate its impact on trace links creation. The results show that the precision increases by an average of 15% (based on the same recall) after adding code comments (even for different trace links creation techniques), and the type of Purpose comments contributes more to the tracing task than the other five. This empirical study provides evidence that code comments are effective in tracing links creation, and different types of code comments contribute differently. Purpose comments can be used to improve the accuracy of requirements-to-code trace links creation.

Effects of governance on entrepreneurship: European Union vs non-European Union

2018 ◽  
Vol 28 (1) ◽  
pp. 43-57 ◽  
Author(s):  
María Jesús Rodríguez-Gulías ◽  
Vítor Manuel de Sousa Gabriel ◽  
David Rodeiro-Pazos
Keyword(s):  
European Union ◽  
The Other ◽  
European Countries ◽  
Content Type ◽  
Government Effectiveness ◽  
Eu Countries ◽  
Governance Indicators ◽  
The Creation ◽  
The Impact ◽  
The Eu

Purpose The purpose of this paper is to analyse the effect of six governance indicators on the rate of creation of new companies between countries that are members of the European Union (EU) and those that are not. H1 states that the various dimensions of governance help to explain the immediate creation of new businesses in European and non-European countries. H2 states that the various dimensions of governance help to explain the deferred creation of new businesses in European and non-European countries. Design/methodology/approach The paper uses two types of analyses: firstly, univariate analysis, which is a descriptive statistics of the dependent, independent and control variables, and the results of a t-test; and secondly, multivariate analysis, which estimates using the fixed-effects estimator under the specifications previously raised for the subsample of 28 EU countries and for the subsample of 103 non-EU countries during the period 2004-2014. Findings The results show that the variables of governance are not significantly higher in the EU, although the density of the enterprises is. Within the governance indicators, government effectiveness is significant in the EU. The results obtained for the EU confirmed H1and H2, with a significant positive effect of government effectiveness on entrepreneurship, while the other governance variables were not significant in the EU subsample. The results obtained for non-EU countries suggest no significant immediate effects (H1) and a slightly significant delayed effect of rule of law on the entrepreneurship (H2) concerned. Research limitations/implications Future research in this area could consider introducing another regional division or other types of methodology as variables affect models. Practical implications Governance can be defined as the ability of a government and its public institutions to provide services and design, and implement rules, which is a factor that affects the creation of new companies. However, the effect of governance could differ depending on the country and its economic environment. This paper analyses the effect of six governance indicators on the rate of creation of new companies considering two different geographic regions as countries are presumably heterogeneous. Therefore, these results indicate that the effect of governance variables on entrepreneurship differs according to the region. Social implications The effect of governance variables on entrepreneurship according to the region is also known. Originality/value This study applied panel data analysis to two samples of countries during the period 2004-2014, one formed by 28 countries of the EU and the other by 103 non-EU countries. No other paper considers this number of countries for this period. To assess the impact of governance on the creation of new companies, this paper considered the existence of immediate and deferred effects of governance on entrepreneurship.

scholarly journals A REFORMA TRABALHISTA E OS REFLEXOS DO FIM DA CONTRIBUIÇÃO SINDICAL COMPULSÓRIA NOS SINDICATOS

Percurso ◽  
2019 ◽  
Vol 2 (29) ◽  
pp. 134
Author(s):  
Debora Cristina de Castro da ROCHA ◽  
Edilson Santos da ROCHA
Keyword(s):  
Trade Unions ◽  
Historical Context ◽  
The Other ◽  
Freedom Of Association ◽  
Labor Reform ◽  
Trade Unionism ◽  
Other Hand ◽  
The Subject ◽  
The Creation ◽  
The Impact

RESUMO Pretende-se com esta pesquisa, uma discussão acerca do impacto da Lei 13.467/2017 ao sindicalismo, no que tange a proibição do desconto ou cobrança sem a prévia e expressa anuência do trabalhador e a voluntariedade da sua ocorrência. Assim, a partir de uma contextualização histórica, busca-se na essência da criação da contribuição sindical, uma maior compreensão dos efeitos da reforma acerca do tema, tendo em vista esta ter tornado facultativa a contribuição, e se especificamente, aos trabalhadores, tal facultatividade poderá contribuir para a liberdade sindical no Brasil, e por outro lado, se esteja diante de um problema de financiamento dos sindicatos profissionais, e por consequência, da própria defesa dos respectivos trabalhadores. Buscar-se-á ainda, discorrer acerca da não recepção da Convenção n. 87 de 1948 pela Constituição de 1988, que dispõe acerca da liberdade sindical. E se a alteração promovida pela Reforma Trabalhista poderá proporcionar maior aproximação dos sindicatos com os trabalhadores, influenciando a anuência com o desconto da contribuição sindical. PALAVRAS-CHAVE: Lei 13.467/2017; Sindicalismo; Contribuição Sindical; Reforma Trabalhista; Liberdade Sindical. ABSTRACT This discussion seeks to discuss the impact of Law 13467/2017 on trade unionism, regarding the prohibition of deduction or collection without the prior and express consent of the worker and the voluntariness of its occurrence. Thus, from a historical context, the essence of the creation of the union contribution is sought, a greater understanding of the effects of the reform on the subject, in order to make the contribution optional, and if specifically to the workers, this faculty can contribute to freedom of association in Brazil, and, on the other hand, there is a problem of financing trade unions and, consequently, the defense of the workers themselves. It will also be sought to find out whether the union uniqueness imposed by the 1988 Constitution could harm Convention No. 87 of 1948 which deals with freedom of association. And if the amendment promoted by the Labor Reform can bring the unions closer to the workers, influencing the agreement with the discount of the union contribution.KEYWORDS: Law 13467/2017; Trade Unionism; Union Contribution; Labor Reform; Freedom Of Association. 

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