The formation of mixed germanium–cobalt carbonyl clusters: an electrospray mass spectrometric study, and the structure of a high-nuclearity [Ge₂Co₁₀(CO)₂₄]²⁻ anion

The reaction of [µ₄-Ge{Co₂(CO)₇}₂] with [Co(CO)₄]⁻ has been monitored by electrospray mass spectrometry to detect the cluster anions generated. Conditions giving known mixed Ge–Co carbonyl clusters were established, and a new high nuclearity cluster anion, [Ge₂Co₁₀(CO)₂₄]²⁻ was detected. Conditions for its formation were optimised and it was subsequently isolated as its [Et₄N]⁺ salt and characterised by single-crystal X-ray crystallography. The Ge₂Co₁₀ cluster core has a novel geometry with the two germanium atoms in semi-encapsulated positions, forming seven formal Ge–Co bonds. There are also eighteen formal Co–Co bonds. Corresponding reactions of [µ₄-Si{Co₂(CO)₇}₂] with [Co(CO)₄]⁻ were also investigated

Ice Conditions in the Gulf of St.Lawrence and Cabot Strait (with particular reference to the Sydney Bight Area)

Les glaces qui, au printemps, se trouvent dans le détroit de Cabot et tout particulièrement dans la région de la baie Sydney, gênent souvent les traversées des bateaux passeurs entre Port-aux-Basques, Terre-Neuve et North Sydney, Nouvelle-Ecosse. Des données sur les principaux relevés des glaces dans le golfe Saint-Laurent et le détroit de Cabot ont été recueillis et étudiées en tenant compte de ce problème.Les relations qui existent entre les nuances de température, les vents et l'étendue des glaces ont été étudiées à la lumière de la statistique. La somme des températures de décembre et janvier correspond assez bien aux principales étendues des glaces qui se trouvaient dans le golfe et le détroit durant ces deux mois. L'étude des vents indique un véritable mouvement de la glace à partir du golfe en direction du détroit durant les années où des observations ont été faites. Si l'on additionne les températures et les vents et les exprime en termes de glace de dérive, on découvre que ces deux éléments sont très étroitement liés l'un à l'autre

Those who left/are left behind : Schrödinger's refugee and the ethics of complementarity

“Those left behind” was a recurring emphasis of media depictions of the emotions surrounding the departure of those who left Afghanistan. The relationship between “those who left” and “those left behind,” which is characteristic of any context of forced displacement, relates to potentials, compelled by life and death questions. A decision to leave or stay is on the surface a binary choice, defined by the physical impossibility of doing both. The purpose of this paper is to explore how the ethical questions change when placed in a framework of quantum complementarity, by which phenomena, defined by what they are not, are also, in important respects, that which they are not, that is, the polar opposite. The first section develops Schrödinger's thought experiment and problematizes his focus on life and death as physical states of the cat, and the separateness of the observer, as a misrepresentation of the Copenhagen School arguments from which the thought experiment arose, and complementarity in particular. The second section examines the relationship between “those who left,” “those left behind,” and external observers in terms of a duality of matter and consciousness, which is complementary and mutually constituted. The third section examines the liminality that arises from a series of nested “boxes” and the various positions from which the forcefully displaced are observed within a holographic world. The final section then unpacks the ethical implications of quantum complementarity and ungrieved grief as they relate to forced displacement.Publisher PDFPeer reviewe

Prediction of the Atomization Energy of Molecules Using Coulomb Matrix and Atomic Composition in a Bayesian Regularized Neural Networks

Exact calculation of electronic properties of molecules is a fundamental step for intelligent and rational compounds and materials design. The intrinsically graph-like and non-vectorial nature of molecular data generates a unique and challenging machine learning problem. In this paper we embrace a learning from scratch approach where the quantum mechanical electronic properties of molecules are predicted directly from the raw molecular geometry, similar to some recent works. But, unlike these previous endeavors, our study suggests a benefit from combining molecular geometry embedded in the Coulomb matrix with the atomic composition of molecules. Using the new combined features in a Bayesian regularized neural networks, our results improve well-known results from the literature on the QM7 dataset from a mean absolute error of 3.51 kcal/mol down to 3.0 kcal/mol.Comment: Under review ICANN 201

Experimental Extraction of Secure Correlations from a Noisy Private State

We report experimental generation of a noisy entangled four-photon state that exhibits a separation between the secure key contents and distillable entanglement, a hallmark feature of the recently established quantum theory of private states. The privacy analysis, based on the full tomographic reconstruction of the prepared state, is utilized in a proof-of-principle key generation. The inferiority of distillation-based strategies to extract the key is exposed by an implementation of an entanglement distillation protocol for the produced state.Comment: 5 pages, 3 figures, final versio

Towards gravitationally assisted negative refraction of light by vacuum

Propagation of electromagnetic plane waves in some directions in gravitationally affected vacuum over limited ranges of spacetime can be such that the phase velocity vector casts a negative projection on the time-averaged Poynting vector. This conclusion suggests, inter alia, gravitationally assisted negative refraction by vacuum.Comment: 6 page

Doubled CO2 Experiments With the Global Change Research Center Two-Dimensional Statistical Dynamical Climate Model

The zonally averaged response of the Global Change Research Center two-dimensional statistical dynamical climate model (GCRC 2-D SDCM) to a doubling of atmospheric carbon dioxide (350 parts per million by volume (ppmv) to 700 ppmv) is reported. The model solves the two-dimensional primitive equations in finite difference form (mass continuity, Newton\u27s second law, and the first law of thermodynamics) for the prognostic variables: zonal mean density, zonal mean zonal velocity, zonal mean meridional velocity, and zonal mean temperature on a grid that has 18 nodes in latitude and 9 vertical nodes (plus the surface). The equation of state, p=rhoRT, and an assumed hydrostatic atmosphere, Deltap=rhogDeltaz, are used to diagnostically calculate the zonal mean pressure and vertical velocity for each grid node, and the moisture balance equation is used to estimate the precipitation rate. The model includes seasonal variations in solar intensity, including the effects of eccentricity, and has observed land and ocean fractions set for each zone. Seasonally varying values of cloud amounts, relative humidity profiles, ozone, and sea ice are all prescribed in the model. Equator to pole ocean heat transport is simulated in the model by turbulent diffusion

RL-DOVS: Reinforcement Learning for Autonomous Robot Navigation in Dynamic Environments

Autonomous navigation in dynamic environments where people move unpredictably is an essential task for service robots in real-world populated scenarios. Recent works in reinforcement learning (RL) have been applied to autonomous vehicle driving and to navigation around pedestrians. In this paper, we present a novel planner (reinforcement learning dynamic object velocity space, RL-DOVS) based on an RL technique for dynamic environments. The method explicitly considers the robot kinodynamic constraints for selecting the actions in every control period. The main contribution of our work is to use an environment model where the dynamism is represented in the robocentric velocity space as input to the learning system. The use of this dynamic information speeds the training process with respect to other techniques that learn directly either from raw sensors (vision, lidar) or from basic information about obstacle location and kinematics. We propose two approaches using RL and dynamic obstacle velocity (DOVS), RL-DOVS-A, which automatically learns the actions having the maximum utility, and RL-DOVS-D, in which the actions are selected by a human driver. Simulation results and evaluation are presented using different numbers of active agents and static and moving passive agents with random motion directions and velocities in many different scenarios. The performance of the technique is compared with other state-of-the-art techniques for solving navigation problems in environments such as ours

Electronic structure of periodic curved surfaces -- topological band structure

Electronic band structure for electrons bound on periodic minimal surfaces is differential-geometrically formulated and numerically calculated. We focus on minimal surfaces because they are not only mathematically elegant (with the surface characterized completely in terms of "navels") but represent the topology of real systems such as zeolites and negative-curvature fullerene. The band structure turns out to be primarily determined by the topology of the surface, i.e., how the wavefunction interferes on a multiply-connected surface, so that the bands are little affected by the way in which we confine the electrons on the surface (thin-slab limit or zero thickness from the outset). Another curiosity is that different minimal surfaces connected by the Bonnet transformation (such as Schwarz's P- and D-surfaces) possess one-to-one correspondence in their band energies at Brillouin zone boundaries.Comment: 6 pages, 8 figures, eps files will be sent on request to [email protected]