Simulation of collisions between two identical meteoroid fragments arranged one behind the other

Author(s):  
V.T. Lukashenko ◽  
F.A. Maksimov

To calculate the dynamics of a system of meteoroid fragments, a simulation method has been developed with an algorithm for calculating collisions between individual bodies. The algorithm for calculating collisions allows one to simulate absolutely elastic, inelastic and absolutely inelastic impacts between individual bodies with the help of a given coefficient of the impact recovery. The impact recovery coefficient can be set separately for each collision based on the known characteristics of the colliding bodies. We carried out a numerical study of the problem of collisions between identical meteoroid fragments initially located one behind the other along the direction of motion. The study shows that bodies will periodically collide in the case of absolutely elastic impact; there is an equilibrium maximum distance between the bodies to which the system will evolve. In the case of an inelastic impact, the distance between the bodies decreases over time; the configuration evolves to the joint flight of the bodies located one right after another. The problem of an absolutely inelastic collision between the identical bodies located within a small initial distance and with a small deviation in position of the backward body shows that the location of the bodies directly behind each other is unstable to small oscillations and is not implemented numerically at large times.

2018 ◽  
Vol 21 (5) ◽  
pp. 663-669 ◽  
Author(s):  
Kisha I Coa ◽  
Kara P Wiseman ◽  
Bryan Higgins ◽  
Erik Augustson

Abstract Introduction Smoking continues to be a leading cause of preventable death. Mobile health (mHealth) can extend the reach of smoking cessation programs; however, user dropout, especially in real-world implementations of these programs, limit their potential effectiveness. Research is needed to understand patterns of engagement in mHealth cessation programs. Methods SmokefreeTXT (SFTXT) is the National Cancer Institute’s 6–8 week smoking cessation text-messaging intervention. Latent growth mixture modeling was used to identify unique classes of engagement among SFTXT users using real-world program data from 7090 SFTXT users. Survival analysis was conducted to model program dropout over time by class, and multilevel modeling was used to explore differences in abstinence over time. Results We identified four unique patterns of engagement groups. The largest percentage of users (61.6%) were in the low-engagers declining group; these users started off with low level of engagement and their engagement decreased over time. Users in this group were more likely to drop out from the program and less likely to be abstinent than users in the other groups. Users in the high engagers–maintaining group (ie, the smallest but most engaged group) were less likely to be daily smokers at baseline and were slightly older than those in the other groups. They were most likely to complete the program and report being abstinent. Conclusions Our findings show the importance of maintaining active engagement in text-based cessation programs. Future research is needed to elucidate predictors of the various levels of engagement, and to assess whether strategies aimed at increasing engagement result in higher abstinence rates. Implications The current study enabled us to investigate differing engagement patterns in non-incentivized program participants, which can help inform program modifications in real-world settings. Lack of engagement and dropout continue to impede the potential effectiveness of mHealth interventions, and understanding patterns and predictors of engagement can enhance the impact of these programs.


2014 ◽  
Vol 611-612 ◽  
pp. 521-528 ◽  
Author(s):  
Laurent Tabourot ◽  
Pascale Balland ◽  
Ndéye Awa Sene ◽  
Mathieu Vautrot ◽  
Nesrine Ksiksi ◽  
...  

This article deals with numerical simulation of necking. It draws the attention onto the importance of the description of strain-hardening and the effects on the evolution of necking. In order to compare necking evolution in relation with different plasticity models, a tracking procedure which consists in determining the evolution over time of discharged volumes of the sample is adopted. Models that take into account physical phenomena at the microscopic level and especially the heterogeneities of materials from a mechanical point of view seem well suited to fit experimental evidence connected to necking.


1998 ◽  
Vol 5 (2) ◽  
pp. 165-195 ◽  
Author(s):  
Haim Gerber

AbstractIn this study I reexamine some well-known generalizations about Islamic law prior to the impact of the West, e.g., the contention that Islamic law became increasingly closed, based more and more on blind imitation. My examination of the fatwā collection of the seventeenth-century Palestinian Muftī Khayr al-Dīn al-Ramlī suggests that increasing closure never took place. On the one hand al-Ramlī faithfully continues the tradition of his classical predecessors, or, in other words, he practices taqlīd by obligating himself to earlier authorities. On the other hand, his fatwās convey a sense of openness, flexibility, and liveliness. These characteristics are concretized in some of the major terms that he uses: ijtihād, or free discretion of the jurist in areas of the law that remained open; iṣtiḥsān, or relaxation of formal rules; and ʿurf, or local customary law, which, by definition, is changeable over time. In my view, the flexibility of Islamic law has been underemphasized in the scholarly literature, and hence it is on this factor in particular that I have chosen to concentrate.


2011 ◽  
Vol 26 (S2) ◽  
pp. 2040-2040
Author(s):  
M. Birchwood

EPOS presented a unique opportunity to document all 'treatments as usual' offered and received in the participating centres to help-seeking patients who fulfilled criteria for UHR status. The EPOS centres were drawn from very different healthcare systems, employing different treatment concepts and using different methods of ascertainment. EPOS ascertained n = 245 UHR patients who were then followed up at 9 and 18 months, taking repeat measures of prodromal symptoms (SIPS), PANSS and depression. In this paper I will describe the different treatments offered in each EPOS centre and the impact of each treatment class on the course of symptoms over time, including ‘transition’ to psychosis. These data will have important bearing on the misnomer of the ‘false positive’ in high risk research and on the other risks and outcomes linked to the UHR/PACE paradigm and their treatment.


1997 ◽  
Vol 11 (4) ◽  
pp. 289-299 ◽  
Author(s):  
Gloria Joachim

Nutrition has an important relationship with health and illness. One difficulty in measuring intake is related to variability. The purpose of this paper is to examine 1) the impact of supply and demand on variability in data collected for dietary studies and 2) the relationship between data and estimates of usual intake. The forces of supply and demand over time generate a consumption curve for each food. Two types of consumption curves are identified. One curve is horizontal and represents staples that are steadily consumed. The other curve exhibits peaks and dips and is unique for each food whose consumption varies with time. The measurement of usual intake is discussed in. light of these two types of curves. Usual intake of foods whose consumption curve is horizontal could be read at any time since consumption does not vary with time. For all other foods, measuring usual consumption presents problems since the data vary with time. This examination indicates that foods whose consumption varies with time have unique properties that must be considered when attempting to calculate consumption. Suggestions are given to enhance measurement of consumption of these foods. Although excellent methodology currently exists for the calculation of intake, attention to the force of supply and demand with only serve to strengthen existing methods.


2019 ◽  
pp. 089484531986169 ◽  
Author(s):  
Jenny Marcionetti ◽  
Jérôme Rossier

Self-esteem, general self-efficacy, and career adaptability, which include career concern, control, curiosity, and confidence, are important resources for adolescents who are required to make important educational and professional choices. No studies have investigated how these resources codevelop over time and their impact on life satisfaction. To more precisely study this codevelopment and the impact of these resources on well-being, 357 Swiss adolescents were assessed 3 times during the last 17 months of compulsory school. The results showed an interrelationship between career adaptability and self-efficacy and a unidirectional effect of self-esteem on life satisfaction over time. They also highlighted the importance of career adapt-ability concerns for predicting the other three career adapt-abilities. Overall, the results suggested that in adolescents, higher levels of career adaptability may favor higher levels of general self-efficacy and that higher levels of self-esteem may induce higher levels of life satisfaction. Implications for practice are discussed.


2021 ◽  
Vol 8 (2) ◽  
pp. 155-162
Author(s):  
Ariffah Isna Amalia

Confucianism is a culture taken from the name of a thinker, namely Confucius and is considered the basis of Confucian teachings. The basic view of Confucianism is to invite people to live an orderly, peaceful and happy life and placing the rulers as one of the key factors in achieving the ideals of the country. The aim of this study is to identify and evaluate the chronology of Confucianism and its implications for China's geopolitical sustainability. The method used is qualitative with constructivist ideas to create a comprehensive thought allocation on the impact of Confucianism from the perspective of cultural superiority. The results obtained are that, over time, Confucianism has developed into a tool for the Chinese state to carry out geopolitical instruments to achieve geostrategy for the expansion of territorial boundaries. On the one hand, Confucianism can become a superior culture that places the fighting spirit of the people. On the other hand, this flow can become a trigger for war when each region that is to be recruited for China's expansion has a culture and beliefs that are different from their own. Keywords: Confucianism, China, Geopolitics, Geostrategy.


2019 ◽  
Author(s):  
Tama Leaver

While social media is, by definition, about connecting multiple people, many discussions about social media platforms and practices presume that accounts and profiles are managed by individual users with the agency to make fully-informed choices about their activities. When discussing children, especially younger children, their agency is at times characterised as partial, or emerging, but with the presumption that with sufficient time they will eventually reach the same (presumed) status and ability as adult users (Livingstone & Third, 2017). At the other end of life, at the moment of death, the social media traces and online presences that persist after a user has passed away also present challenges in terms of agency. While there is an increasing push to include some sort of instructions about digital property in wills, these instructions are currently few and far between. Some platforms have deployed algorithmic solutions which have begun to address the reality of deceased users, but these are, at best, partial and largely insufficient responses. With these two figures in mind, I argue that the very young—from conception to birth and early infancy—and the recently deceased both act as liminal figures where the question of their (lack of) agency on social media highlights some of the ongoing challenges in presuming that social media traces can always be the responsibility of users with full, or even partial, agency. Rather, using a range of examples, I argue in this chapter that more encompassing ways of thinking about the relationship between social media, networked selves and identities, are needed. Drawing on work from the creative industries, I suggest that the term co-creation can be reframed to emphasise the way that social media almost always entails creating other people’s identities as much as our own. Parents and carers are the first arbiters and co-creators of a young person’s life, making a large number of important choices about what sort of private or public online presence a newly born baby will have, how that presence will develop over time, on which platforms, and under which circumstances. Parents, in effect, can choose to name their children into being online, and in doing so must navigate the parental joys of sharing whilst balancing this against the rights of the child to, amongst other things, privacy in the present and future. At the other end of life, but in functionally similar ways, the loved ones left behind by the recently deceased will often need to make decisions about which social media profiles and traces persist after that user has died, how these traces will be (re)framed, and what online spaces will persist (if any), possibly in the form of online memorials. Moreover, both ends of life are now situated in an online context where real identities and real names, which persist over time, are both expected and demanded by the policies and practices of online platforms. The use of real names on social media amplifies the impact and longevity of social media traces, whether early or late in life. In outlining the challenges inherent in framing the very young, and the recently deceased, online, I argue in this chapter that a broader sense of agency and impact is needed across all life-stages on social media. A wider lens in terms of the way users contribute to the stories of each other on social media may well assist us all in making decisions about online material that inevitably impact the lives and legacies of other people.


Author(s):  
Marcin Palenik

Abstract The preference to receive benefits as early as possible and delay costs as much as possible is natural for people. That means a positive discount rate in the intertemporal choice, which is a common assumption in economics. However, as research in behavioral economics proves, in certain situations a negative discount rate occurs. The purpose of this paper is to show that the assumption of positive discounting is not always true. The presented experimental study shows how a decrease in probability increases the chances of negative discounting. According to the results, the expected large, uncertain profit is more likely to be deferred over time than a certain profit of the same value. On the other hand, the expected large, uncertain loss is more willingly experienced earlier than a certain loss of the same value. In both cases, it means an increase in the frequency of negative discounting due to increased uncertainty. The results of the study broaden the existing knowledge about the impact of probability on discounting in a situation of expected losses and the area of negative discounting.


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