Exchange-correlation energy and potential as approximate functionals of occupied and virtual Kohn-Sham orbitals: Application to dissociating H-2

The standard local density approximation and generalized gradient approximations fail to properly describe the dissociation of an electron pair bond, yielding large errors (on the order of 50 kcal/mol) at long bond distances. To remedy this failure, a self-consistent Kohn-Sham (KS) method is proposed with the exchange-correlation (xc) energy and potential depending on both occupied and virtual KS orbitals. The xc energy functional of Buijse and Baerends [Mol. Phys. 100, 401 (2002); Phys. Rev. Lett. 87, 133004 (2001)] is employed, which, based on an ansatz for the xc-hole amplitude, is able to reproduce the important dynamical and nondynamical effects of Coulomb correlation through the efficient use of virtual orbitals. Self-consistent calculations require the corresponding xc potential to be obtained, to which end the optimized effective potential (OEP) method is used within the common energy denominator approximation for the static orbital Green's function. The problem of the asymptotic divergence of the xc potential of the OEP when a finite number of virtual orbitals is used is addressed. The self-consistent calculations reproduce very well the entire H-2 potential curve, describing correctly the gradual buildup of strong left-right correlation in stretched H-2. (C) 2003 American Institute of Physics.

Prospective, Randomized Assessment of Transfer of Training (ToT) and Transfer Effectiveness Ratio (TER) of Virtual Reality Simulation Training for Laparoscopic Skill Acquisition

OBJECTIVES:: We assessed the effectiveness of ToT from VR laparoscopic simulation training in 2 studies. In a second study, we also assessed the TER. ToT is a detectable performance improvement between equivalent groups, and TER is the observed percentage performance differences between 2 matched groups carrying out the same task but with 1 group pretrained on VR simulation. Concordance between simulated and in-vivo procedure performance was also assessed. DESIGN:: Prospective, randomized, and blinded. PARTICIPANTS:: In Study 1, experienced laparoscopic surgeons (n = 195) and in Study 2 laparoscopic novices (n = 30) were randomized to either train on VR simulation before completing an equivalent real-world task or complete the real-world task only. RESULTS:: Experienced laparoscopic surgeons and novices who trained on the simulator performed significantly better than their controls, thus demonstrating ToT. Their performance showed a TER between 7% and 42% from the virtual to the real tasks. Simulation training impacted most on procedural error reduction in both studies (32- 42%). The correlation observed between the VR and real-world task performance was r > 0·96 (Study 2). CONCLUSIONS:: VR simulation training offers a powerful and effective platform for training safer skills.

Exploring Virtual-Channel architecture in FPGA based Networks-on-Chip

A novel Networks-on-Chip (NoC) router architecture specified for FPGA based implementation with configurable Virtual-Channel (VC) is presented. Each pipeline stage of the proposed architecture has been optimized so that low packet propagation latency and reduced hardware overhead can be achieved. The proposed architecture enables high performance and cost effective VC NoC based on-chip system interconnects to be deployed on FPGA.

Hermit crabs perceive the extent of their virtual bodies

A flexible body image is required by animals if they are to adapt to body changes and move effectively within a structurally complex environment. Here, we show that terrestrial hermit crabs, Coenobita rugosus, which frequently change shells, can modify walking behaviour, dependent on the shape of the shell. Hermit crabs walked along a corridor that had alternating left and right corners; if it was narrow at the corner, crabs rotated their bodies to avoid the wall, indicating an awareness of environmental obstacles. This rotation increased when a plastic plate was attached to the shell. We suggest that the shell, when extended by the plate, becomes assimilated to the hermit crab's own body. While there are cases of a tool being assimilated with the body, our result is the first example of the habitat where an animal lives and/or carries being part of a virtual body. This journal is © 2012 The Royal Society.

The phase diagram of water at negative pressures: Virtual ices

The phase diagram of water at negative pressures as obtained from computer simulations for two models of water, TIP4P/2005 and TIP5P is presented. Several solid structures with lower densities than ice Ih, so-called virtual ices, were considered as possible candidates to occupy the negative pressure region of the phase diagram of water. In particular the empty hydrate structures sI, sII, and sH and another, recently proposed, low-density ice structure. The relative stabilities of these structures at 0 K was determined using empirical water potentials and density functional theory calculations. By performing free energy calculations and Gibbs-Duhem integration the phase diagram of TIP4P/2005 was determined at negative pressures. The empty hydrates sII and sH appear to be the stable solid phases of water at negative pressures. The phase boundary between ice Ih and sII clathrate occurs at moderate negative pressures, while at large negative pressures sH becomes the most stable phase. This behavior is in reasonable agreement with what is observed in density functional theory calculations.

Creating a Circus of Words, Music, and Sound: From Roaratorio to Owenvarragh

This article documents the creation of a work by the authors based on a score written by the composer John Cage entitled 'Owenvarragh: A Belfast Circus on The Star Factory.' The article is part of a documentary portfolio in the journal which also includes a volume of the poetry created by Dowling in accordance with the instructions of the Cage score, and a series of documentary videos on the creation of the work and its first performance. Cage's score is based on his work 'Roaratorio: An Irish Circus on Finnegan's Wake' (1979) and it provides a set of detailed instructions for the musical realisation of a literary work. The article documents this first fully realised version of the score since Cage first produced 'Roaratorio' in 1979. The work, which was motivated by the Cage centenary year in 2012, musically realises Carson's book 'The Star Factory' (1998), a novelestic autobiography of Carson's Belfast childhood. The score required the creation of a fixed media piece based on over 300 field recordings of the sounds and places mentioned in the book, a volume of poetry created from the book which is recited to form the rhythmic spine of the work, and the arrangement of a performance including these two components along with live musical performance by the authors in collaboration with three other musicians under their direction, and a video installation created for the work. The piece has been performed three times: in association with the Sonorities 2012 Festival at Queen's University of Belfast (March 2012), at The Belfast Festival at Queen's (October 2012), and in the Rymer Auditoium of the University of York (June 2013).

Additional information:

The work which the article documents was conceived by Monaghan and Dowling, and the project was initiated by Monaghan after a she received a student prize to support its development and first performance. Elements of the project will be included in her PhD dissertation for which Dowling is a supervisor. Monaghan created the fixed media piece based on over 300 field recordings, the largest single aspect of realising Cage's score. Dowling was responsible for initiating the collaboration with Ciaran Carson, and for two other components: the creation of a volume of poetry derived from the literary work which is recited in the performance, and the creation of and supervision of the technical work on a video which accompanies the piece. The co-authors consulted closely during the work on these large components from May 2011 until March 2012 when the first performance took place. The co-authors also shared in numerous other artistic and organisational aspects of the production, including the arrangement and performnance of the music, musical direction to other performers, and marketing.

Reading Elizabeth Bishop's "Artifact of [Words]"

As Emerson noted in his essay 'The Poet' "we are not pans and barrows, not even porters of the fire and torch-bearers, but children of the fire, made of it, and only the same divinity transmuted, and at two or three removes, when we least know about it." For Emerson, the fire is poetry, an elemental force capable of transmutation, transformation and enduring relevance. Moving from Emerson, Elizabeth Bishop rises as the twentieth-century poet most aligned with the possibility of poetry and the powers of its practice, as 'At The Fishhouses' indicates in her clear referencing of Emerson:

"If you should dip your hand in,
your wrist would ache immediately,
your bones would begin to ache and your hand would burn
as if the water were a transmutation of fire
that feeds on stones and burns with a dark gray flame."

This essay will look in detail at Bishop's understanding of the possibility of poetry and how art functions as a multi-dimensional structure that is unsettled as much as it unsettles. In particular, Bishop's poem 'The Monument' will be unpicked as testament both to the practice of Bishop's art and also the role of the poet critic responding to what they uncover

Laugh-aware virtual agent and its impact on user amusement

In this paper we present a complete interactive system en- abled to detect human laughs and respond appropriately, by integrating the information of the human behavior and the context. Furthermore, the impact of our autonomous laughter-aware agent on the humor experience of the user and interaction between user and agent is evaluated by sub- jective and objective means. Preliminary results show that the laughter-aware agent increases the humor experience (i.e., felt amusement of the user and the funniness rating of the film clip), and creates the notion of a shared social experience, indicating that the agent is useful to elicit posi- tive humor-related affect and emotional contagion.

Automated Methods for Virtual Maintainability & Aerospace Maintenance Planning

Abstract. Modern business practices in engineering are increasingly turning to post manufacture service provision in an attempt to generate additional revenue streams and ensure commercial sustainability. Maintainability has always been a consideration during the design process but in the past it has been generally considered to be of tertiary importance behind manufacturability and primary product function in terms of design priorities. The need to draw whole life considerations into concurrent engineering (CE) practice has encouraged companies to address issues such as maintenance, earlier in the design process giving equal importance to all aspects of the product lifecycle. The consideration of design for maintainability (DFM) early in the design process has the potential to significantly reduce maintenance costs, and improve overall running efficiencies as well as safety levels. However a lack of simulation tools still hinders the adaptation of CE to include practical elements of design and therefore further research is required to develop methods by which ‘hands on’ activities such as maintenance can be fully assessed and optimised as concepts develop. Virtual Reality (VR) has the potential to address this issue but the application of these traditionally high cost systems can require complex infrastructure and their use has typically focused on aesthetic aspects of mature designs. This paper examines the application of cost effective VR technology to the rapid assessment of aircraft interior inspection during conceptual design. It focuses on the integration of VR hardware with a typical desktop engineering system and examines the challenges with data transfer, graphics quality and the development of practical user functions within the VR environment. Conclusions drawn to date indicate that the system has the potential to improve maintenance planning through the provision of a usable environment for inspection which is available as soon as preliminary structural models are generated as part of the conceptual design process. Challenges still exist in the efficient transfer of data between the CAD and VR environments as well as the quantification of any benefits that result from the proposed approach. The result of this research will help to improve product maintainability, reduce product development cycle times and lower maintenance costs.

Developing virtual patients for medical microbiology education

The landscape of medical education is changing as students embrace the accessibility and interactivity of e-learning. Virtual patients are e-learning resources that may be used to advance microbiology education. Although the development of virtual patients has been widely considered, here we aim to provide a coherent approach for clinical educators.

Self-healing systems and virtual structures

Modern networks are large, highly complex and dynamic. Add to that the mobility of the agents comprising many of these networks. It is difficult or even impossible for such systems to be managed centrally in an efficient manner. It is imperative for such systems to attain a degree of self-management. Self-healing i.e. the capability of a system in a good state to recover to another good state in face of an attack, is desirable for such systems. In this paper, we discuss the self-healing model for dynamic reconfigurable systems. In this model, an omniscient adversary inserts or deletes nodes from a network and the algorithm responds by adding a limited number of edges in order to maintain invariants of the network. We look at some of the results in this model and argue for their applicability and further extensions of the results and the model. We also look at some of the techniques we have used in our earlier work, in particular, we look at the idea of maintaining virtual graphs mapped over the existing network and assert that this may be a useful technique to use in many problem domains.