Frequency intermittency and energy pumping by linear attachments

Cataloged from PDF version of article.The present paper considers the problem of realizing an effective targeted energy pumping from a linear oscillator to a set of ungrounded linear resonators attached to it. Theoretical as well as numerical results demonstrate the efficacy of using a complex attachment as a passive absorber of broadband energy injected into the primary structure. The paper unveils also the existence of an instantaneous frequency associated with the master response characterized by intermittency: a rather surprising result for a linear autonomous system. Comparison with nonlinear energy sinks demonstrates that the two systems have some analogies in this respect and that the linear complex attachment is a very efficient energy trap. (C) 2014 Elsevier Ltd. All rights reserved

Spinal microcircuits comprising dI3 interneurons are necessary for motor functional recovery following spinal cord transection

The spinal cord has the capacity to coordinate motor activities such as locomotion. Following spinal transection, functional activity can be regained, to a degree, following motor training. To identify microcircuits involved in this recovery, we studied a population of mouse spinal interneurons known to receive direct afferent inputs and project to intermediate and ventral regions of the spinal cord. We demonstrate that while dI3 interneurons are not necessary for normal locomotor activity, locomotor circuits rhythmically inhibit them and dI3 interneurons can activate these circuits. Removing dI3 interneurons from spinal microcircuits by eliminating their synaptic transmission left locomotion more or less unchanged, but abolished functional recovery, indicating that dI3 interneurons are a necessary cellular substrate for motor system plasticity following transection. We suggest that dI3 interneurons compare inputs from locomotor circuits with sensory afferent inputs to compute sensory prediction errors that then modify locomotor circuits to effect motor recovery

Sex Stereotypes of Adolescents in Traffic: The Role of Sex and Family Relationships (Trafikte Ergenlerin Cinsiyet Kalıp Yargıları: Cinsiyet ve Aile İlişkilerinin Rolü)

Studies have shown a number of differences between male and female drivers, such as male drivers committing more offenses and female drivers making more errors. Related to this persistent sex difference, relatively little research has been conducted to examine the presence of gender stereotypes and determinants in the context of driving. This study examined the perceptions of female and male drivers among adolescents in Türkiye and how sex differences and relationships with parents contributed to the endorsement of sex stereotypes. The study was conducted with 128 high school adolescents aged 15-20 years (M = 16.25, SD = 1.32) who completed a questionnaire package consisting of the Sex Stereotypes Associated with Driving (SSAD) and a demographic information form. In terms of sex stereotype endorsement indices, female adolescents reported female drivers as more polite and risk-averse, whereas male adolescents reported male drivers as more skilled. While a positive relationship with fathers reduced the endorsement of courtesy and risk-avoidance stereotypes, a better relationship with mothers resulted in a lower endorsement of the driving skills stereotype. The results provide evidence for the existence of sex stereotypes among adolescents and for the importance of family relationships in relation to sex stereotype endorsement. The findings can be used to design training and education that focuses on stereotypes at an early age. (Araştırmalar, erkek ve kadın sürücüler arasında, erkek sürücülerin daha fazla trafik cezası alması ve kadın sürücülerin daha fazla hata yapması gibi bir dizi farklılık olduğunu göstermektedir. Gözlemlenen bu cinsiyet farklılığına bağlı olarak, sürüş bağlamında toplumsal cinsiyet kalıp yargılarının ve belirleyicilerinin varlığını inceleyen nispeten az sayıda araştırma yapılmıştır. Bu çalışma, Türkiye'deki ergenlerin kadın ve erkek sürücü algılarını ve cinsiyet farklılıklarının ve ebeveynlerle ilişkilerin cinsiyet kalıp yargılarının onaylanmasına nasıl katkıda bulunduğunu incelemiştir. Çalışma, Sürücülükle İlişkili Cinsiyet Kalıp Yargıları (SSAD) ve demografik bilgi formundan oluşan bir anket paketini dolduran 15-20 yaş arası 128 lise çağındaki ergen (M = 16.25, SD = 1.32) ile yürütülmüştür. Cinsiyet stereotipi onay endeksleri açısından, kız ergenler kadın sürücüleri daha kibar ve riskten kaçınan olarak bildirirken, erkek ergenler erkek sürücüleri daha becerikli olarak bildirmiştir. Babalarla olumlu bir ilişki nezaket ve riskten kaçınma kalıp yargılarının onaylanmasını azaltırken, annelerle daha iyi bir ilişki sürüş becerileri kalıp yargısının daha az onaylanmasıyla sonuçlanmıştır. Sonuçlar, ergenler arasında cinsiyet kalıp yargılarının varlığına ve aile ilişkilerinin cinsiyet kalıp yargılarının onaylanması açısından önemine dair kanıtlar sunmaktadır. Bulgular, erken yaşta kalıp yargılara odaklanan eğitim ve müdahale çalışmalarının tasarlanmasında kullanılabilir.

Review of Linac-Ring Type Collider Proposals

There are three possibly types of particle colliders schemes: familiar (well known) ring-ring colliders, less familiar however sufficiently advanced linear colliders and less familiar and less advanced linac-ring type colliders. The aim of this paper is two-fold: to present possibly complete list of papers on linac-ring type collider proposals and to emphasize the role of linac-ring type machines for future HEP research.Comment: quality of figures is improved, some misprints are correcte

Behavioural intention of e-scooter use: A comparison of users and non-users

In the present study, the behavioural intention and factors affecting the use of e-scooters were examined among young people in Turkey. Previous users and non-users of e-scooters were compared in relation to the various variables. The relationships of attitudes, subjective norms, perceived behavioural control, and perceived usefulness were investigated regarding the intention to use e-scooters. While users reported positive socio-psychological factors related to e-scooter use, all different factors were positively related to behavioural intention. The results highlighted the importance of socio-psychological factors in predicting behavioural intention, as well as differences between e-scooter users and non-users in these factors

Energy equipartition and frequency distribution in complex attachments

As reported in several recent publications, an undamped simple oscillator with a complex attachment that consists of a set of undamped parallel resonators can exhibit unusual energy sharing properties. The conservative set of oscillators of the attachment can absorb nearly all the impulsive energy applied to the primary oscillator to which it is connected. The key factor in the ability of the attachment to absorb energy with near irreversibility correlates with the natural frequency distribution of the resonators within it. The reported results also show that a family of optimal frequency distributions can be determined on the basis of a variational approach, minimizing a certain functional related to the system response. The present paper establishes a link between these optimal frequency distributions and the energy equipartition principle: optimal frequency distributions are those that spread the injected energy as uniformly as possible over the degrees of freedom or over the modes of the system. Theoretical as well as numerical results presented support this point of view. © 2009 Acoustical Society of America

Vibration absorption using non-dissipative complex attachments with impacts and parametric stiffness

Studies on prototypical systems that consist of a set of complex attachments, coupled to a primary structure characterized by a single degree of freedom system, have shown that vibratory energy can be transported away from the primary through use of complex undamped resonators. Properties and use of these subsystems as by energy absorbers have also been proposed, particularly using attachments that consist of a large set of resonators. These ideas have been originally developed for linear systems and they provided insight into energy sharing phenomenon in large structures like ships, airplanes, and cars, where interior substructures interact with a master structure, e.g., the hull, the fuselage, or the car body. This paper examines the effects of nonlinearities that develop in the attachments, making them even more complex. Specifically, two different nonlinearities are considered: (1) Those generated by impacts that develop among the attached resonators, and (2) parametric effects produced by time-varying stiffness of the resonators. Both the impacts and the parametric effects improve the results obtained using linear oscillators in terms of inhibiting transported energy from returning to the primary structure. The results are indeed comparable with those obtained using linear oscillators but with special frequency distributions, as in the findings of some recent papers by the same authors. Numerically obtained results show how energy is confined among the attached oscillators. © 2009 Acoustical Society of America