Expressions for forces and torques in molecular simulations using rigid bodies

Expressions for intermolecular forces and torques, derived from pair potentials between rigid non-spherical units, are presented. The aim is to give compact and clear expressions, which are easily generalised, and which minimise the risk of error in writing molecular dynamics simulation programs. It is anticipated that these expressions will be useful in the simulation of liquid crystalline systems, and in coarse-grained modelling of macromolecules

Chip-based array of near-identical, pure, heralded single-photon sources

Interference between independent single photons is perhaps the most fundamental interaction in quantum optics. It has become increasingly important as a tool for optical quantum information science, as one of the rudimentary quantum operations, together with photon detection, for generating entanglement between non-interacting particles. Despite this, demonstrations of large-scale photonic networks involving more than two independent sources of quan- tum light have been limited due to the difficulty in constructing large arrays of high-quality, single-photon sources. Here, we solve the key challenge, reporting on a novel array of five near-identical, low-loss, high-purity, heralded single-photon sources using spontaneous four-wave mixing on a silica chip. We verify source quality through a series of heralded Hong – Ou – Mandel (HOM) experiments, and further report the experimental three-photon extension of the HOM interference effect, which maps out for the first time, to our knowledge, the interference landscape between three independent single-photon sources

Developing the virtuous self in an online MBA: Reflections on instruments and processes

The relationship between virtue ethics and leadership is profound and has been the subject of sustained examination (see, for example, Fontrodona, et al. 2012). The core of these debates has centred on the way in which a life of the good, conceived as a process of self- awareness built through experience and reflection, has the capacity to comprise the people who inhabit, lead, and constitute organizations. Prima facie management education ought to entail the explicit development of the virtuous self, rather than this education being of a residual type. This requires a more reflective approach to management practice. We are challenged in this endeavour by our status as providers of online education. Our central concern in this paper is to provide an account of a Leadership Development ePortfolio, particularly its development to a program of online leadership skill development. This includes, among other skills, the development of reflective practice skills, development of self-awareness, self-mastery (Senge, 1990), and a consideration of how to apply those skills to others (e.g.: mentoring) and with others (e.g.: team learning, service learning). We argue that introducing these elements to a program fosters the development of ethically virtuous management graduates

Chip-based array of near-identical, pure, heralded single-photon sources

Interference between independent single photons is perhaps the most fundamental interaction in quantum optics. It has become increasingly important as a tool for optical quantum information science, as one of the rudimentary quantum operations, together with photon detection, for generating entanglement between non-interacting particles. Despite this, demonstrations of large-scale photonic networks involving more than two independent sources of quan- tum light have been limited due to the difficulty in constructing large arrays of high-quality, single-photon sources. Here, we solve the key challenge, reporting on a novel array of five near-identical, low-loss, high-purity, heralded single-photon sources using spontaneous four-wave mixing on a silica chip. We verify source quality through a series of heralded Hong – Ou – Mandel (HOM) experiments, and further report the experimental three-photon extension of the HOM interference effect, which maps out for the first time, to our knowledge, the interference landscape between three independent single-photon sources

A proposed testbed for detector tomography

Measurement is the only part of a general quantum system that has yet to be characterized experimentally in a complete manner. Detector tomography provides a procedure for doing just this; an arbitrary measurement device can be fully characterized, and thus calibrated, in a systematic way without access to its components or its design. The result is a reconstructed POVM containing the measurement operators associated with each measurement outcome. We consider two detectors, a single-photon detector and a photon-number counter, and propose an easily realized experimental apparatus to perform detector tomography on them. We also present a method of visualizing the resulting measurement operators.Comment: 9 pages, 4 figure

Thalidomide-induced Teratogenesis : History and Mechanisms

Peer reviewedPublisher PD

Cardiac adaptations from 4 weeks of intensity-controlled vigorous exercise are lost after a similar period of detraining

Intensity‐controlled (relative to VO2max) treadmill exercise training in adult rats results in the activation and ensuing differentiation of endogenous c‐kitpos cardiac stem/progenitor cells (eCSCs) into newly formed cardiomyocytes and capillaries. Whether these training‐induced adaptations persist following detraining is undetermined. Twelve male Wistar rats (~230 g) were exercised at 80–85% of their VO2max for 30 min day−1, 4 days week−1 for 4 weeks (TR; n = 6), followed by 4 weeks of detraining (DTR; n = 6). Twelve untrained rats acted as controls (CTRL). Exercise training significantly enhanced VO2max (11.34 mL kg−1 min−1) and wet heart weight (29%) above CTRL (P < 0.05). Echocardiography revealed that exercise training increased LV mass (~32%), posterior and septal wall thickness (~15%), ejection fraction and fractional shortening (~10%) compared to CTRL (P < 0.05). Cardiomyocyte diameter (17.9 ± 0.1 μm vs. 14.9 ± 0.6 μm), newly formed (BrdUpos/Ki67pos) cardiomyocytes (7.2 ± 1.3%/1.9 ± 0.7% vs. 0.2 ± 0.1%/0.1 ± 0.1%), total cardiomyocyte number (45.6 ± 0.6 × 106 vs. 42.5 ± 0.4 × 106), c‐kitpos eCSC number (884 ± 112 per 106 cardiomyocytes vs. 482 ± 132 per 106 cardiomyocytes), and capillary density (4123 ± 227 per mm2 vs. 2117 ± 118 per mm2) were significantly greater in the LV of trained animals (P < 0.05) than CTRL. Detraining removed the stimulus for c‐kitpos eCSC activation (640 ± 98 per 106 cardiomyocytes) and resultant cardiomyocyte hyperplasia (0.4 ± 0.3% BrdUpos/0.2 ± 0.2% Ki67pos cardiomyocytes). Capillary density (3673 ± 374 per mm2) and total myocyte number (44.7 ± 0.5 × 106) remained elevated following detraining, but cardiomyocyte hypertrophy (15.0 ± 0.4 μm) was lost, resulting in a reduction of anatomical (wall thickness ~4%; LV mass ~10% and cardiac mass ~8%, above CTRL) and functional (EF & FS ~2% above CTRL) parameters gained through exercise training. These findings demonstrate that cardiac adaptations, produced by 4 weeks of intensity‐controlled exercise training are lost after a similar period of detraining

Objective Ultrasonic Characterization of Welding Defects Using Physically Based Pattern Recognition Techniques

Computer-based methods for analysing ultrasonic data to distinguish between different defect types have been based on a variety of techniques such as adaptive learning [1], artificial intelligence [2] and statistical pattern recognition [3]. The uncertain classification reliability of these techniques when applied to a range of realistic defect types has, however, often been a significant practical limitation to their use

Quantum teleportation on a photonic chip

Quantum teleportation is a fundamental concept in quantum physics which now finds important applications at the heart of quantum technology including quantum relays, quantum repeaters and linear optics quantum computing (LOQC). Photonic implementations have largely focussed on achieving long distance teleportation due to its suitability for decoherence-free communication. Teleportation also plays a vital role in the scalability of photonic quantum computing, for which large linear optical networks will likely require an integrated architecture. Here we report the first demonstration of quantum teleportation in which all key parts - entanglement preparation, Bell-state analysis and quantum state tomography - are performed on a reconfigurable integrated photonic chip. We also show that a novel element-wise characterisation method is critical to mitigate component errors, a key technique which will become increasingly important as integrated circuits reach higher complexities necessary for quantum enhanced operation.Comment: Originally submitted version - refer to online journal for accepted manuscript; Nature Photonics (2014

Functional Analysis of Missense Mutations in Kv8.2 Causing Cone Dystrophy with Supernormal Rod Electroretinogram

Mutations in KCNV2 have been proposed as the molecular basis for cone dystrophy with supernormal rod electroretinogram. KCNV2 codes for the modulatory voltage-gated potassium channel α-subunit, Kv8.2, which is incapable of forming functional channels on its own. Functional heteromeric channels are however formed with Kv2.1 in heterologous expression systems, with both α-subunit genes expressed in rod and cone photoreceptors. Of the 30 mutations identified in the KCNV2 gene, we have selected three missense mutations localized in the potassium channel pore and two missense mutations localized in the tetramerization domain for analysis. We characterized the differences between homomeric Kv2.1 and heteromeric Kv2.1/Kv8.2 channels and investigated the influence of the selected mutations on the function of heteromeric channels. We found that two pore mutations (W467G and G478R) led to the formation of nonconducting heteromeric Kv2.1/Kv8.2 channels, whereas the mutations localized in the tetramerization domain prevented heteromer generation and resulted in the formation of homomeric Kv2.1 channels only. Consequently, our study suggests the existence of two distinct molecular mechanisms involved in the disease pathology