82 research outputs found

    Off-lining to tape is not archiving: Why we need real archiving to support media archaeology and ensure our visual effects legacy thrives

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    © 2019 ISAST This paper examines digital asset archiving and preservation practice in the visual effects (VFX) industry. The authors briefly summarize media archaeology theory and provide an overview of how VFX studios presently archive project assets and records, based on case study and interview research conducted with expert VFX practitioners from leading international studios. In addition, the authors propose that current practice could be improved by adopting archival science methods, including digital preservation practices. Doing so will support media archaeology studies of digital cultures over time and ensure that the legacy of VFX creative and technical production thrives for future generations

    Quantum entanglement between electronic and vibrational degrees of freedom in molecules

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    We consider the quantum entanglement of the electronic and vibrational degrees of freedom in molecules with a tendency towards double welled potentials using model coupled harmonic diabatic potential-energy surfaces. The von Neumann entropy of the reduced density matrix is used to quantify the electron-vibration entanglement for the lowest two vibronic wavefunctions in such a bipartite system. Significant entanglement is found only in the region in which the ground vibronic state contains a density profile that is bimodal (i.e., contains two separate local minima). However, in this region two distinct types of entanglement are found: (1) entanglement that arises purely from the degeneracy of energy levels in the two potential wells and which is destroyed by slight asymmetry, and (2) entanglement that involves strongly interacting states in each well that is relatively insensitive to asymmetry. These two distinct regions are termed fragile degeneracy-induced entanglement and persistent entanglement, respectively. Six classic molecular systems describable by two diabatic states are considered: ammonia, benzene, semibullvalene, pyridine excited triplet states, the Creutz-Taube ion, and the radical cation of the "special pair" of chlorophylls involved in photosynthesis. These chemically diverse systems are all treated using the same general formalism and the nature of the entanglement that they embody is elucidated

    Perspective: Accurate ro-vibrational calculations on small molecules

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    In what has been described as the fourth age of quantum chemistry, variational nuclear motion programs are now routinely being used to obtain the vibration-rotation levels and corresponding wavefunctions of small molecules to the sort of high accuracy demanded by comparison with spectroscopy. In this perspective, I will discuss the current state-of-the-art which, for example, shows that these calculations are increasingly competitive with measurements or, indeed, replacing them and thus becoming the primary source of data on key processes. To achieve this accuracy ab initio requires consideration of small effects, routinely ignored in standard calculations, such as those due to quantum electrodynamics. Variational calculations are being used to generate huge lists of transitions which provide the input for models of radiative transport through hot atmospheres and to fill in or even replace measured transition intensities. Future prospects such as the study of molecular states near dissociation, which can provide a link with low-energy chemical reactions, are discussed

    ExoMol molecular line lists – XXVI: spectra of SH and NS

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    Line lists for the sulphur-containing molecules SH (the mercapto radical) and NS are computed as part of the ExoMol project. These line lists consider transitions within the X2Π ground state for 32SH, 33SH, 34SH,36SH and, 32SD, and 14N32S, 14N33S, 14N34S, 14N36S, and 15N32S. Ab initio potential energy (PEC) and spin-orbit coupling (SOC) curves are computed and then improved by fitting to experimentally observed transitions. Fully ab initio dipole moment curves (DMCs) computed at high level of theory are used to produce the final line lists. For SH, our fit gives a root-mean-square (rms) error of 0.03 cm−1 between the observed (⁠vmax = 4, Jmax = 34.5) and calculated transitions wavenumbers; this is extrapolated such that all X2Π rotational-vibrational-electronic (rovibronic) bound states are considered. For 32SH the resulting line list contains about 81 000 transitions and 2300 rovibronic states, considering levels up to vmax = 14 and Jmax = 60.5. For NS the refinement used a combination of experimentally determined frequencies and energy levels and led to an rms-fitting error of 0.002 cm−1. Each NS-calculated line list includes around 2.8 million transitions and 31 000 rovibronic states with a vibrational range up to v = 53 and rotational range up to J = 235.5, which covers up to 23 000 cm−1. Both line lists should be complete for temperatures up to 5000 K. Example spectra simulated using this line list are shown and comparisons made to the existing data in the CDMS data base. The line lists are available from the CDS (http://cdsarc.u-strasbg.fr) and ExoMol (www.exomol.com) data bases

    A Revised Forensic Process for Aligning the Investigation Process with the Design of Forensic-Enabled Cloud Services

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    © Springer Nature Switzerland AG 2020. The design and implementation of cloud services, without taking under consideration the forensic requirements and the investigation process, makes the acquisition and examination of data, complex and demanding. The evidence gathered from the cloud may not become acceptable and admissible in the court. A literature gap in supporting software engineers so as to elicit and model forensic-related requirements exists. In order to fill the gap, software engineers should develop cloud services in a forensically sound manner. In this paper, a brief description of the cloud forensic-enabled framework is presented (adding some new elements) so as to understand the role of the design of forensic-enabled cloud services in a cloud forensic investigation. A validation of the forensic requirements is also produced by aligning the stages of cloud forensic investigation process with the framework’s forensic requirements. In this way, on one hand, a strong relationship is built between these two elements and emphasis is given to the role of the forensic requirements and their necessity in supporting the investigation process. On the other hand, the alignment assists towards the identification of the degree of the forensic readiness of a cloud service against a forensic investigation

    A framework for designing cloud forensic‑enabled services (CFeS)

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    Cloud computing is used by consumers to access cloud services. Malicious actors exploit vulnerabilities of cloud services to attack consumers. The link between these two assumptions is the cloud service. Although cloud forensics assists in the direction of investigating and solving cloud-based cyber-crimes, in many cases the design and implementation of cloud services falls back. Software designers and engineers should focus their attention on the design and implementation of cloud services that can be investigated in a forensic sound manner. This paper presents a methodology that aims on assisting designers to design cloud forensic-enabled services. The methodology supports the design of cloud services by implementing a number of steps to make the services cloud forensic-enabled. It consists of a set of cloud forensic constraints, a modelling language expressed through a conceptual model and a process based on the concepts identified and presented in the model. The main advantage of the proposed methodology is the correlation of cloud services’ characteristics with the cloud investigation while providing software engineers the ability to design and implement cloud forensic-enabled services via the use of a set of predefined forensic related task
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