The Coordination Chemistry of the N-Donor-Substituted Phosphazanes.

Phosph(III)azanes, featuring the heterocyclobutane P2 N2 ring, have now been established as building blocks in main-group coordination and supramolecular compounds. Previous studies have largely involved their use as neutral P-donor ligands or as anionic N-donor ligands, derived from deprotonation of amido-phosphazanes [RNHP(μ-NR)]2 . The use of neutral amido-phosphazanes themselves as chelating, H-bond donors in anion receptors has also been an area of recent interest because of the ease by which the proton acidity and anion binding constants can be modulated, by the incorporation of electron-withdrawing exo- and endo-cyclic groups (R) and by the coordination of transition metals to the ring P atoms. We observed recently that the effect of P,N-chelation of metal atoms to the P atoms of cis-[(2-py)NHP(μ-Nt Bu)]2 (2-py=2-pyridyl) not only pre-organises the N-H functionality for optimum H-bonding to anions but also results in a large increase in anion binding constants, well above those for traditional organic receptors like squaramides and ureas. Here, we report a broader investigation of ligand chemistry of [(2-py)NHP(μ-t NBu)]2 (and of the new quinolyl derivative [(8-Qu)NHP(μ-Nt Bu)]2 (8-Qu=8-quinolyl). The additional N-donor functionality of the heterocyclic substituents and its position has a marked effect on the anion and metal coordination chemistry of both species, leading to novel structural behaviour and reactivity compared to unfunctionalized counterparts.Cambridge Trus

The infrared imaging spectrograph (IRIS) for TMT: spectrograph design

The Infra-Red Imaging Spectrograph (IRIS) is one of the three first light instruments for the Thirty Meter Telescope (TMT) and is the only one to directly sample the diffraction limit. The instrument consists of a parallel imager and off-axis Integral Field Spectrograph (IFS) for optimum use of the near infrared (0.84um-2.4um) Adaptive Optics corrected focal surface. We present an overview of the IRIS spectrograph that is designed to probe a range of scientific targets from the dynamics and morphology of high-z galaxies to studying the atmospheres and surfaces of solar system objects, the latter requiring a narrow field and high Strehl performance. The IRIS spectrograph is a hybrid system consisting of two state of the art IFS technologies providing four plate scales (4mas, 9mas, 25mas, 50mas spaxel sizes). We present the design of the unique hybrid system that combines the power of a lenslet spectrograph and image slicer spectrograph in a configuration where major hardware is shared. The result is a powerful yet economical solution to what would otherwise require two separate 30m-class instruments.Comment: 15 pages, 11 figure

Flexible Bonding of the Phosph(V)azane Dianions [S(E)P(μ‐NtBu)]22−

Producción CientíficaOxidation of the PIII dianion [S−P(μ‐NtBu)]22− (1) with elemental sulphur, selenium and tellurium gives the PV dianions [(S)(E)P(μ‐NtBu)]22− (E = S (6 a), Se (6 b), Te (6 c)). Although 6 c proves to be too unstable, the S,S‐dianion 6 a and ambidentate S,Se‐dianion 6 b are readily transferred intact to main group and transition metal elements, producing a range of new cage and coordination compounds. While their coordination characteristics are in many ways similar to closely‐related isoelectronic phosph(V)azane anions [(E)(RN=)P(μ‐NtBu)]22−, the sterically unhindered nature of 6 introduces an expanded range of coordination modes, that is, facial S,S‐ and Se,Se‐bonding as well as side‐on S,Se‐coordination. All of these bonding modes are observed for the amibidentate S,Se dianion 6 b.2019-04-04Ministerio de Economía, Industria y Competitividad - Agencia Estatal de Investigación (AEI)European Social Fund (ESF)Ramon y Cajal contract (RG-R, RYC-2015 -19035

Proximity Operations for the Robotic Boulder Capture Option for the Asteroid Redirect Mission

In September of 2013, the Asteroid Robotic Redirect Mission (ARRM) Option B team was formed to expand on NASA's previous work on the robotic boulder capture option. While the original Option A concept focuses on capturing an entire smaller Near-Earth Asteroid (NEA) using an inflatable bag capture mechanism, this design seeks to land on a larger NEA and retrieve a boulder off of its surface. The Option B team has developed a detailed and feasible mission concept that preserves many aspects of Option A's vehicle design while employing a fundamentally different technique for returning a significant quantity of asteroidal material to the Earth-Moon system. As part of this effort, a point of departure proximity operations concept was developed complete with a detailed timeline, as well as DeltaV and propellant allocations. Special attention was paid to the development of the approach strategy, terminal descent to the surface, controlled ascent with the captured boulder, and control during the Enhanced Gravity Tractor planetary defense demonstration. The concept of retrieving a boulder from the surface of an asteroid and demonstrating the Enhanced Gravity Tractor planetary defense technique is found to be feasible and within the proposed capabilities of the Asteroid Redirect Vehicle (ARV). While this point of departure concept initially focuses on a mission to Itokawa, the proximity operations design is also shown to be extensible to wide range of asteroids

Deep Markov Random Field for Image Modeling

Markov Random Fields (MRFs), a formulation widely used in generative image modeling, have long been plagued by the lack of expressive power. This issue is primarily due to the fact that conventional MRFs formulations tend to use simplistic factors to capture local patterns. In this paper, we move beyond such limitations, and propose a novel MRF model that uses fully-connected neurons to express the complex interactions among pixels. Through theoretical analysis, we reveal an inherent connection between this model and recurrent neural networks, and thereon derive an approximated feed-forward network that couples multiple RNNs along opposite directions. This formulation combines the expressive power of deep neural networks and the cyclic dependency structure of MRF in a unified model, bringing the modeling capability to a new level. The feed-forward approximation also allows it to be efficiently learned from data. Experimental results on a variety of low-level vision tasks show notable improvement over state-of-the-arts.Comment: Accepted at ECCV 201

Becoming a (green) identity entrepreneur: learning to negotiate situated identities to nurture community environmental practice

This paper explores the relationship between ‘green’ identity and community environmental practice. It focuses on the ways in which professional community development facilitators and lead members of community groups attempt to actively shape how environmental projects are locally received. Drawing principally on identity, social sustainability and social practice theory scholarship, it reviews the often very personal and place-specific ways in which appeals to green identity are variously understood and applied, or are actively avoided, by community group leaders. Individuals who have become skilful in negotiating and influencing the presentation of environmental projects to the local community are understood here as (green) identity entrepreneurs. Arguably, it is the situated entrepreneurial skilfulness of lead individuals in negotiating the multiple and evolving (green) identities circulating through any one project, which plays a significant part in determining its subsequent impact and longevity. In understanding the contribution of (green) identity entrepreneurship, however, its relational association with everyday practices, routines and meanings of community and place is brought to the fore. The paper also considers how divergent external interpretations of what constitutes legitimate environmental practice at a local level further shape project identity. The discussion is informed by evidence drawn from a qualitative study of seventeen community groups and seven professional environmental support officers participating in a Welsh Government led programme aimed at facilitating 'community action on climate change'

Deprotonation, insertion and isomerisation in the post-functionalisation of tris-pyridyl aluminates

Producción CientíficaPost-functionalisation of the aluminate anion [EtAl(6-R-2-py)3]− (6-R-2-py = 6-R-2-pyridyl, R = Me or Br) can be accomplished via nucleophilic addition of the pyridyl groups to the electrophilic C[double bond, length as m-dash]O group of aldehydes (RCH[double bond, length as m-dash]O) or by deprotonation of carboxylic acids (RCO2H). NMR spectroscopic and crystallographic studies show how 6-Me-2-py groups can detect chirality and reveal a new aspect of isomerism.Ministerio de Economía, Industria y Competitividad - Agencia Estatal de Investigación - Fondo Social Europeo (Ramon y Cajal contract RG-R, RYC-2015-19035)

The coordination chemistry of the neutral tris-2-pyridyl silicon ligand [PhSi(6-Me-2-py)3]

Producción CientíficaDifficulties in the preparation of neutral ligands of the type [RSi(2-py)3] (where 2-py is an unfunctionalised 2-pyridyl ring unit) have thwarted efforts to expand the coordination chemistry of ligands of this type. However, simply switching the pyridyl substituents to 6-methyl-pyridyl groups (6-Me-2-py) in the current paper has allowed smooth, high-yielding access to the [PhSi(6-Me-2-py)3] ligand (1), and the first exploration of its coordination chemistry with transition metals. The synthesis, single-crystal X-ray structures and solution dynamics of the new complexes [{PhSi(6-Me-2-py)3}CuCH3CN][PF6], [{PhSi(6-Me-2-py)3}CuCH3CN][CuCl2], [{PhSi(6-Me-2-py)3}FeCl2], [{PhSi(6-Me-2-py)3}Mo(CO)3] and [{PhSi(6-Me-2-py)3}CoCl2] are reported. The paramagnetic Fe2+ and Co2+ complexes show strongly shifted NMR resonances for the coordinated pyridyl units due to large Fermi-contact shifts. However, magnetic anisotropy also leads to considerable pseudo-contact shifts so that both contributions have to be included in the paramagnetic NMR analysis.The Leverhulme Trust (Grant for DSW and RG-R, postdoctoral funding for ALC, RGP-2017-146Ministerio de Economía, Industria y Competitividad - Agencia Estatal de Investigación (AEI)European Social Fund (ESF)Ramón y Cajal contract (RG-R, RYC-2015–19035

MiSearch adaptive pubMed search tool

Summary: MiSearch is an adaptive biomedical literature search tool that ranks citations based on a statistical model for the likelihood that a user will choose to view them. Citation selections are automatically acquired during browsing and used to dynamically update a likelihood model that includes authorship, journal and PubMed indexing information. The user can optionally elect to include or exclude specific features and vary the importance of timeliness in the ranking

Objects and categories: feature statistics and object processing in the ventral stream.

Recognizing an object involves more than just visual analyses; its meaning must also be decoded. Extensive research has shown that processing the visual properties of objects relies on a hierarchically organized stream in ventral occipitotemporal cortex, with increasingly more complex visual features being coded from posterior to anterior sites culminating in the perirhinal cortex (PRC) in the anteromedial temporal lobe (aMTL). The neurobiological principles of the conceptual analysis of objects remain more controversial. Much research has focused on two neural regions-the fusiform gyrus and aMTL, both of which show semantic category differences, but of different types. fMRI studies show category differentiation in the fusiform gyrus, based on clusters of semantically similar objects, whereas category-specific deficits, specifically for living things, are associated with damage to the aMTL. These category-specific deficits for living things have been attributed to problems in differentiating between highly similar objects, a process that involves the PRC. To determine whether the PRC and the fusiform gyri contribute to different aspects of an object's meaning, with differentiation between confusable objects in the PRC and categorization based on object similarity in the fusiform, we carried out an fMRI study of object processing based on a feature-based model that characterizes the degree of semantic similarity and difference between objects and object categories. Participants saw 388 objects for which feature statistic information was available and named the objects at the basic level while undergoing fMRI scanning. After controlling for the effects of visual information, we found that feature statistics that capture similarity between objects formed category clusters in fusiform gyri, such that objects with many shared features (typical of living things) were associated with activity in the lateral fusiform gyri whereas objects with fewer shared features (typical of nonliving things) were associated with activity in the medial fusiform gyri. Significantly, a feature statistic reflecting differentiation between highly similar objects, enabling object-specific representations, was associated with bilateral PRC activity. These results confirm that the statistical characteristics of conceptual object features are coded in the ventral stream, supporting a conceptual feature-based hierarchy, and integrating disparate findings of category responses in fusiform gyri and category deficits in aMTL into a unifying neurocognitive framework.This work was supported by a grant from the Medical Research Council (G0500842) to L. K. T., a British Academy (Grant Number LRG-45583) grant to L. K. T. and K. I. T., a Newton Trust grant to L. K. T. and K. I. T., the European Research Council (ERC) under the European Community ʼs Seventh Framework Programme (FP7/2007 – 2013)/ERC (Grant Agreement Number 249640) to L. K. T., and a Swiss National Science Foundation Ambizione Fellowship (Grant Number PZ00P1_126493) to K. I. T.This is the accepted version of the original publication available at: http://dx.doi.org/10.1162/jocn_a_00419 in Journal of Cognitive Neuroscience http://www.mitpressjournals.org/loi/joc