Paper of the Week – My life and the world of crystals Ian Robinson played a central role during the most exciting era in surface physics, as this area blossomed and reached its apex during the 1980s. "My life and the world of crystals" is a perfect synopsis of how the structures and properties of solid surfaces finally came to be understood. The wide range of new techniques, including (among many others) low energy electron diffraction, synchrotron radiation spectroscopies, surface x-ray diffraction, and scanning tunneling microscopy, are discussed from the point of view of one of the most active participants. Perhaps a climax, as described in detail, was the achievement of the Holy Grail: the structure of the Si(7x7) surface. And then one moves into the present, with Bragg coherent diffraction imaging applied to nanostructures, and anticipates the future, with free electron lasers and time domain crystallography.
Virtual issue: Mixing in fusion plasmas
With Guest Editors Snezhana I Abarzhi, Michael E Mauel and Harold Weitzner, this virtual issue comprises a collection of papers that were presented at, and are relevant to, the mini-conference Mixing in Fusion Plasmas and the programme 'Turbulent Mixing and Beyond'.
Highlights of 2014
Don't miss our new collection of papers, celebrating the research that was published with us last year. All the papers are free to read until 31 December 2015.
Virtual issue: Emerging technologies and the future of humanity
This virtual issue of Physica Scripta grew out of the one-day meeting 'Emerging technologies and the future of humanity' that took place on March 17, 2014, at the Royal Swedish Academy of Sciences. The backdrop of the discussions at the meeting is the realization that technologies developed in the next few decades can have profound influence on the future of humanity.
Crystallography and the Gregori Aminoff Prize
To mark the fact that 2014 has been designated the 'International Year of Crystallography', Physica Scripta will be publishing a virtual issue containing Invited Comments on the history of crystallography, as well as autobiographical articles from some of the current and previous winners of the Gregori Aminoff Prize. You can read the first papers published in this virtual issue here.
In the last 30 days
Garry Robinson and Ian Robinson 2015 Phys. Scr. 90 028004
In ‘swing’ bowling, as employed by fast and fast-medium bowlers in cricket, back-spin along the line of the seam is normally applied in order to keep the seam vertical and to provide stability against ‘wobble’ of the seam. Whilst spin is normally thought of as primarily being the slow bowlerʼs domain, the spin applied by the swing bowler has the side-effect of generating a lift or Magnus force. This force, depending on the orientation of the seam and hence that of the back-spin, can have a side-ways component as well as the expected vertical ‘lift’ component. The effect of the spin itself, in influencing the trajectory of the fast bowlerʼs delivery, is normally not considered, presumably being thought of as negligible. The purpose of this paper is to investigate, using calculated model trajectories, the amount of side-ways movement due to the spin and to see how this predicted movement compares with the total observed side-ways movement. The size of the vertical lift component is also estimated.
It is found that, although the spin is an essential part of the successful swing bowlerʼs delivery, the amount of side-ways movement due to the spin itself amounts to a few centimetres or so, and is therefore small, but perhaps not negligible, compared to the total amount of side-ways movement observed. The spin does, however, provide a considerable amount of lift compared to the equivalent delivery bowled without spin, altering the point of pitching by up to 3 m, a very large amount indeed. Thus, for example, bowling a ball with the seam pointing directly down the pitch and not designed to swing side-ways at all, but with the amount of back-spin varied, could provide a very powerful additional weapon in the fast bowlerʼs arsenal. So-called ‘sling bowlers’, who use a very low arm action, can take advantage of spin since effectively they can apply side-spin to the ball, giving rise to a large side-ways movement, cm or more, which certainly is significant. For a given amount of spin the amount of side-ways movement increases as the bowlerʼs delivery arm becomes more horizontal. This technique could also be exploited by normal spin bowlers as well as swing bowlers.
María A H Vozmediano and F Guinea 2012 Phys. Scr. 2012 014015
We give an update of the situation concerning the effect of electron–electron interactions on the physics of a neutral graphene system at low energies. We revise old renormalization group results and the use of 1/ N expansion to address questions of the possible opening of a low-energy gap, and the magnitude of the graphene fine structure constant. We emphasize the role of Fermi velocity as the only free parameter determining the transport and electronic properties of the graphene system and revise its renormalization by Coulomb interactions in the light of recent experimental evidence.
Kaj Sotala and Roman V Yampolskiy 2015 Phys. Scr. 90 018001
Many researchers have argued that humanity will create artificial general intelligence (AGI) within the next twenty to one hundred years. It has been suggested that AGI may inflict serious damage to human well-being on a global scale (‘catastrophic risk’). After summarizing the arguments for why AGI may pose such a risk, we review the fieldʼs proposed responses to AGI risk. We consider societal proposals, proposals for external constraints on AGI behaviors and proposals for creating AGIs that are safe due to their internal design.
David A Keen 2014 Phys. Scr. 89 128003
X-ray crystallography was initiated by physicists in the early 20th century. However—as is common with many developments in physics—the subject quickly moved beyond the confines of physics to produce key advances in chemistry, biology, mineralogy and materials science. This article discusses the role of physics in developing crystallography over the last 100 years and the relevance of crystallography to physics today. It is concluded that although crystallography has become somewhat hidden within physics departments it is still a key component of modern condensed matter physics.
Sukang Bae et al 2012 Phys. Scr. 2012 014024
Since the first isolation of graphene in 2004 by mechanical exfoliation from graphite, many people have tried to synthesize large-scale graphene using various chemical methods. In particular, there has been a great number of advances in the synthesis of graphene using chemical vapor deposition (CVD) on metal substrates such as Ni and Cu. Recently, a method to synthesize ultra-large-scale (~30 inch) graphene films using roll-to-roll transfer and chemical doping processes was developed that shows excellent electrical and physical properties suitable for practical applications on a large scale. Considering the outstanding scalability/processibility of roll-to-roll and CVD methods as well as the extraordinary flexibility/conductivity of graphene films, we expect that transparent graphene electrodes can replace indium tin oxide in the near future.
Garry Robinson and Ian Robinson 2013 Phys. Scr. 88 018101
In this paper the differential equations which govern the motion of a spherical projectile rotating about an arbitrary axis in the presence of an arbitrary ‘wind’ are developed. Three forces are assumed to act on the projectile: (i) gravity, (ii) a drag force proportional to the square of the projectile's velocity and in the opposite direction to this velocity and (iii) a lift or ‘Magnus’ force also assumed to be proportional to the square of the projectile's velocity and in a direction perpendicular to both this velocity and the angular velocity vector of the projectile. The problem has been coded in Matlab and some illustrative model trajectories are presented for ‘ball-games’, specifically golf and cricket, although the equations could equally well be applied to other ball-games such as tennis, soccer or baseball.
Spin about an arbitrary axis allows for the treatment of situations where, for example, the spin has a component about the direction of travel. In the case of a cricket ball the subtle behaviour of so-called ‘drift’, particularly ‘late drift’, and also ‘dip’, which may be produced by a slow bowler's off or leg-spin, are investigated. It is found that the trajectories obtained are broadly in accord with those observed in practice. We envisage that this paper may be useful in two ways: (i) for its inherent scientific value as, to the best of our knowledge, the fundamental equations derived here have not appeared in the literature and (ii) in cultivating student interest in the numerical solution of differential equations, since so many of them actively participate in ball-games, and they will be able to compare their own practical experience with the overall trends indicated by the numerical results.
As the paper presents equations which can be further extended, it may be of interest to research workers. However, since only the most basic principles of fundamental mechanics are employed, it should be well within the grasp of first year university students in physics and engineering and, with the guidance of teachers, good final year secondary school students. The trajectory results included may be useful to sporting personnel with no formal training in physics.
K S Novoselov and A H Castro Neto 2012 Phys. Scr. 2012 014006
Graphene is just one example of a large class of two-dimensional crystals. These crystals can either be extracted from layered three-dimensional materials or grown artificially by several different methods. Furthermore, they present physical properties that are unique because of the low dimensionality and their special crystal structure. They have potential for semiconducting behavior, magnetism, superconductivity, and even more complex many-body phenomena. Two-dimensional crystals can also be assembled in three-dimensional heterostructures that do not exist in nature and have tailored properties, opening an entirely new chapter in condensed matter research.
Hong Yang and Li Juan Ning 2015 Phys. Scr. 90 045202
The effects of global and local time delay on a genotype selection model driven by multiplicative and additive noises are investigated. The stationary probability distributions are derived using the small delay approximation and numerical simulations, respectively. The influences of different time delays on the stationary probability distribution are discussed. It is found that both global and local time delay can induce phase transitions, but the changes are totally different. Moreover, multiplicative and additive noise can induce phase transition whether the time delay is global or not.
D J Dunstan and D J Hodgson 2014 Phys. Scr. 89 068002
Many gardeners and horticulturalists seek non-chemical methods to control populations of snails. It has frequently been reported that snails that are marked and removed from a garden are later found in the garden again. This phenomenon is often cited as evidence for a homing instinct. We report a systematic study of the snail population in a small suburban garden, in which large numbers of snails were marked and removed over a period of about 6 months. While many returned, inferring a homing instinct from this evidence requires statistical modelling. Monte Carlo techniques demonstrate that movements of snails are better explained by drift under the influence of a homing instinct than by random diffusion. Maximum likelihood techniques infer the existence of two groups of snails in the garden: members of a larger population that show little affinity to the garden itself, and core members of a local garden population that regularly return to their home if removed. The data are strongly suggestive of a homing instinct, but also reveal that snail-throwing can work as a pest management strategy.
Yigong Shi 2014 Phys. Scr. 89 068004
As a Chinese born and raised in central China, I came to the United States for graduate education in 1990. Eighteen years later, I resigned my tenured faculty position at Princeton University and returned to my alma mater Tsinghua University. In this review, I share my experiences and reflections as a graduate student, a postdoctoral fellow, and an independent scientist in both Princeton and Beijing. Much focus is given to my research effort in the field of programmed cell death (also known as apoptosis). Systematic structural biology, which combines x-ray crystallography with other biochemical and biophysical methods, has led to comprehensive understanding of the underlying molecular mechanisms that govern the initiation, execution, and regulation of apoptosis.