Winning strategies in congested traffic

One-directional traffic on two-lanes is modeled in the framework of a spring-block type model. A fraction $q$ of the cars are allowed to change lanes, following simple dynamical rules, while the other cars keep their initial lane. The advance of cars, starting from equivalent positions and following the two driving strategies is studied and compared. As a function of the parameter $q$ the winning probability and the average gain in the advancement for the lane-changing strategy is computed. An interesting phase-transition like behavior is revealed and conclusions are drawn regarding the conditions when the lane changing strategy is the better option for the drivers.Comment: 5 pages, 5 figure

Breakdown of a conservation law in incommensurate systems

We show that invariance properties of the Lagrangian of an incommensurate system, as described by the Frenkel Kontorova model, imply the existence of a generalized angular momentum which is an integral of motion if the system remains floating. The behavior of this quantity can therefore monitor the character of the system as floating (when it is conserved) or locked (when it is not). We find that, during the dynamics, the non-linear couplings of our model cause parametric phonon excitations which lead to the appearance of Umklapp terms and to a sudden deviation of the generalized momentum from a constant value, signalling a dynamical transition from a floating to a pinned state. We point out that this transition is related but does not coincide with the onset of sliding friction which can take place when the system is still floating.Comment: 7 pages, 6 figures, typed with RevTex, submitted to Phys. Rev. E Replaced 27-03-2001: changes to text, minor revision of figure

Theoretical Study of Friction: A Case of One-Dimensional Clean Surfaces

A new method has been proposed to evaluate the frictional force in the stationary state. This method is applied to the 1-dimensional model of clean surfaces. The kinetic frictional force is seen to depend on velocity in general, but the dependence becomes weaker as the maximum static frictional force increases and in the limiting case the kinetic friction gets only weakly dependent on velocity as described by one of the laws of friction. It is also shown that there is a phase transition between state with vanishing maximum static frictional force and that with finite one. The role of randomness at the interface and the relation to the impurity pinning of the sliding Charge-Density-Wave are discussed. to appear in Phys.Rev.B. abstract only. Full text is available upon request. E-mail: [email protected]: 2 pages, Plain TEX, OUCMT-94-

Thermal effects on atomic friction

We model friction acting on the tip of an atomic force microscope as it is dragged across a surface at non-zero temperatures. We find that stick-slip motion occurs and that the average frictional force follows $|\ln v|^{2/3}$, where $v$ is the tip velocity. This compares well to recent experimental work (Gnecco et al, PRL 84, 1172), permitting the quantitative extraction of all microscopic parameters. We calculate the scaled form of the average frictional force's dependence on both temperature and tip speed as well as the form of the friction-force distribution function.Comment: Accepted for publication, Physical Review Letter

Importância de variáveis ambientais na soma térmica de cultivares de trigo.

Orientador: Genei Antonio Dalmago

Femtosecond laser microstructuring of zirconia dental implants

This study evaluated the suitability of femtosecond laser for microtexturizing cylindrical zirconia dental implants surface. Sixty-six cylindrical zirconia implants were used and divided into three groups: Control group (with no laser modification), Group A (microgropored texture), and Group B (microgrooved texture). Scanning electron microscopy observation of microgeometries revealed minimal collateral damage of the original surface surrounding the treated areas. Optical interferometric profilometry showed that ultrafast laser ablation increased surface roughness (Ra, Rq, Rz, and Rt) significantly for both textured patterns from 1.2× to 6×-fold when compared with the control group (p Group B 8.4% ± 0.42% > Group A 1.6% ± 0.35%) and aluminum (Control 4.3% ± 0.9% > Group B 2.3% ± 0.3% > Group A 1.16% ± 0.2%) in the laser-treated surfaces (p Group A 1.94% > Group B 1.72%) as the surfaces were processed with ultrashort laser pulses. We concluded that femtosecond laser microstructuring offers an interesting alternative to conventional surface treatments of zirconia implants as a result of its precision and minimal damage of the surrounding areas

Alexithymia and depression in elderly people that get directed physical activity

La relación entre la alexitimia y la depresión y los factores sociodemográficos ha sido estudiada en personas mayores. Sin embargo, el papel atenuador del ejercicio en estas afecciones aún debe ser determinado. En el presente estudio se mide el grado de alexitimia y depresión en adultos mayores, comparando una muestra sedentaria con una de practicantes de actividad física. Se utilizó un diseño descriptivo transversal con una muestra compuesta por 27 participantes, 9 hombres y 18 mujeres de más de 60 años (64 ± 5.1 años), con objeto de medir el grado de alexitimia y depresión que presentaban en el momento de la recogida de datos. Los instrumentos utilizados fueron la escala de depresión de Yesavage, la Escala de Alexitimia de Toronto (TAS-20) y el Cuestionario de Salud SF-12. Los resultados mostraron que los practicantes de actividad física presentaban puntuaciones más bajas en alexitimia y depresión que los sujetos sedentarios, sin que éstas variables estuvieran relacionadas en función del género y la edad. A tenor de los resultados, el ejercicio pudiera jugar algún papel en la modulación de las alteraciones psicológicas

Co-creating sociotechnical visions for a circular metal economy transition in the UK

The UK government's target of achieving net-zero emissions by 2050 has created an urgent need for decarbonization and the transition towards a circular metal economy (CME). The production of steel and aluminium, critical components of modern industry, contribute significantly to greenhouse gas emissions and are the focus of this paper. This paper explores the barriers and enablers involved in moving towards a CME. Although recycling is an essential strategy for metal recovery, it may not suffice to achieve the UK government's net-zero objectives. The paper suggests twelve preferred visions for a CME, encompassing the entire metal value chain, co-created through collaboration with over one hundred industry and academic experts. These visions can serve as a foundation for co-design workshops for academics to investigate additional barriers and enablers within the metal sector. Within corporate management, these visions can be used to set targets and guide decision-making towards specific circular and sustainable goals. Finally, policymakers can use these visions to develop a roadmap or comprehend the implications and rebound effects of a CME transition for the UK.UKRI National Interdisciplinary Circular Economy Research programme (NICER)

2050 Circular Metal Visions

This progress report was produced within the UKRI Interdisciplinary Centre for Circular Metals (Principal Investigator Prof Zhongyun Fan), as part of the activities of WP3 ‘Circular Business’ (led by Prof Janet Godsell) and work stream WP3.1 ‘Circular business model innovation’ (led by Dr Fabrizio Ceschin).This progress report presents some initial findings of the WP3 ’Circular Business’ of the UKRI Interdisciplinary Centre for the Circular Metals. The aim of the centre is to transform the metals industry and make the UK the first country in the world to have a fully circular metals system. The purpose of this progress report is to present a set of visions of how circular economy can transform the metal value chain in the long term. The progress report presents 12 visions for 2050 and discusses the most significant challenges and opportunities that might respectively hinder and support the shift to those visions. The progress report is the result of research activities that brought together leading experts from academia, industry, and government to explore how the UK could transition to a circular metal economy

Non-motor Behavioral Alterations of PGC-1 alpha-Deficient Mice - A Peculiar Phenotype With Slight Male Preponderance and No Apparent Progression

Dysfunction of peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1 alpha) has been linked to various neurodegenerative and neuropsychiatric disorders; however, reports on psychic behavioral alterations on PGC-1 alpha-deficient animals are sparse. The present study revisited prior observations of anxiety-related, depression-related, and hippocampal memory-related observations having been made on different PGC-1 alpha-deficient murine strains, in a large-scale analysis on whole-body full-length (FL-)PGC-1 alpha-deficient mice. The examinations were performed on animals covering a wide age range enrolled from both sexes, and included paradigms such as the open-field, elevated plus maze, light-dark box, tail suspension test, and spatial recognition two-trial V-maze. The findings revealed no signs of previously reported anxiety-like behavior, but revealed an unexpected phenotype with decreased anxiety behavior consistent throughout different paradigms, with slight male preponderance. This was associated with despair-like anhedonic behavior, consistent with that reported previously, but did not associate with either peripheral or brain alterations in kynurenic acid synthesis, which was previously proposed. Though male FL-PGC-1 alpha-deficient mice tended to perform poorer in the hippocampus-based spatial learning paradigm, the genotype overall was not associated with impairment in spatial memory, contradicting with prior observations. None of the observed alterations deteriorated with age, similarly to motor alterations as reported previously. The most likely contributors of this peculiar phenotype are discussed, with clinicopathological correlations drawn. Being the first to address these behavioral domains within the same PGC-1 alpha-deficient strain, our findings extend the knowledge about the complex in vivo effect of PGC-1 alpha dysfunction and add important notes to research in the field of PGC-1 alpha in connection with neuropsychiatric disorders