Taxonomy and biostratigraphy of new and emended species of Cenozoic deep-water agglutinated foraminifera from the Labrador and North Seas

Deep marine, fine grained sedimentary strata of Maastrichtian through Miocene age in the Labrador and North Sea sedimentary basins are rich in agglutinated benthic foraminifera. Six new taxa have been found in these regions, several of which also extend to other circum-Atlantic Paleogene localities. The new taxa are: Ammomarginulina aubertae, n. sp. (Maastrichtian to Eocene), Adercotryma agterbergi, n. sp. (middle Eocene to lower Oligocene), Reticulophragmoides jarvisi (Thalmann) emended herein (Paleocene to lower Oligocene), Reticulophragmoides sp. 5 (Oligocene to Miocene), and Spiroplectammina navarroana Cushman emended herein (Maastrichtian to lower middle Eocene). The last occurrences of these taxa are important elements in the high-resolution probabilistic biozonations for the Labrador and North Sea basins

Novel Neutron Detectors based on the Time Projection Method

We present the first prototype of a novel thermal neutron detector using the time projection method. The system consists of 8 TimePix ASICS with postprocessed InGrid meshes. Each ASIC has 256 x 256 pixels of 55 mum x 55mum in size with the capability to measure charge or time. This allows to visualize entire conversion particle tracks with their spatial and time information and, by using event reconstruction algorithms, discriminate against the background of others. By using the Scalable Readout System the detector as presented here could also be upscaled to much larger active areas. In the current configuration we could achieve a spatial resolution of $\sigma = (115\pm8)$ mum.Comment: Paper submitted to Physica B: Condensed Matter special issue: Proceedings ICNS 201

An automaton over data words that captures EMSO logic

We develop a general framework for the specification and implementation of systems whose executions are words, or partial orders, over an infinite alphabet. As a model of an implementation, we introduce class register automata, a one-way automata model over words with multiple data values. Our model combines register automata and class memory automata. It has natural interpretations. In particular, it captures communicating automata with an unbounded number of processes, whose semantics can be described as a set of (dynamic) message sequence charts. On the specification side, we provide a local existential monadic second-order logic that does not impose any restriction on the number of variables. We study the realizability problem and show that every formula from that logic can be effectively, and in elementary time, translated into an equivalent class register automaton

Persistence and Uncertainty in the Academic Career

Understanding how institutional changes within academia may affect the overall potential of science requires a better quantitative representation of how careers evolve over time. Since knowledge spillovers, cumulative advantage, competition, and collaboration are distinctive features of the academic profession, both the employment relationship and the procedures for assigning recognition and allocating funding should be designed to account for these factors. We study the annual production n_{i}(t) of a given scientist i by analyzing longitudinal career data for 200 leading scientists and 100 assistant professors from the physics community. We compare our results with 21,156 sports careers. Our empirical analysis of individual productivity dynamics shows that (i) there are increasing returns for the top individuals within the competitive cohort, and that (ii) the distribution of production growth is a leptokurtic "tent-shaped" distribution that is remarkably symmetric. Our methodology is general, and we speculate that similar features appear in other disciplines where academic publication is essential and collaboration is a key feature. We introduce a model of proportional growth which reproduces these two observations, and additionally accounts for the significantly right-skewed distributions of career longevity and achievement in science. Using this theoretical model, we show that short-term contracts can amplify the effects of competition and uncertainty making careers more vulnerable to early termination, not necessarily due to lack of individual talent and persistence, but because of random negative production shocks. We show that fluctuations in scientific production are quantitatively related to a scientist's collaboration radius and team efficiency.Comment: 29 pages total: 8 main manuscript + 4 figs, 21 SI text + fig

High-repetition-rate combustion thermometry with two-line atomic fluorescence excited by diode lasers

We report on kilohertz-repetition-rate flame temperature measurements performed using blue diode lasers. Two-line atomic fluorescence was performed by using diode lasers emitting at around 410 and 451 nm to probe seeded atomic indium. At a repetition rate of 3.5 kHz our technique offers a precision of 1.5% at 2000 K in laminar methane/air flames. The spatial resolution is better than 150 mu m, while the setup is compact and easy to operate, at much lower cost than alternative techniques. By modeling the spectral overlap between the locked laser and the probed indium lines we avoid the need for any calibration of the measurements. We demonstrate the capability of the technique for time-resolved measurements in an acoustically perturbed flame. The technique is applicable in flames with a wide range of compositions including sooting flames

Nanoscopic insights into seeding mechanisms and toxicity of α-synuclein species in neurons.

New strategies for visualizing self-assembly processes at the nanoscale give deep insights into the molecular origins of disease. An example is the self-assembly of misfolded proteins into amyloid fibrils, which is related to a range of neurodegenerative disorders, such as Parkinson's and Alzheimer's diseases. Here, we probe the links between the mechanism of α-synuclein (AS) aggregation and its associated toxicity by using optical nanoscopy directly in a neuronal cell culture model of Parkinson's disease. Using superresolution microscopy, we show that protein fibrils are taken up by neuronal cells and act as prion-like seeds for elongation reactions that both consume endogenous AS and suppress its de novo aggregation. When AS is internalized in its monomeric form, however, it nucleates and triggers the aggregation of endogenous AS, leading to apoptosis, although there are no detectable cross-reactions between externally added and endogenous protein species. Monomer-induced apoptosis can be reduced by pretreatment with seed fibrils, suggesting that partial consumption of the externally added or excess soluble AS can be significantly neuroprotective.We thank Dr Q. Jeng and Dr A. Stephens for technical assistance and Dr J. Skepper for TEM imaging. This work was funded by grants from the U.K. Medical Research Council (MR/K015850/1 and MR/K02292X/1), Alzheimer’s Research UK (ARUK-EG2012A-1), U.K. Engineering and Physical Sciences Research Council (EPSRC) (EP/H018301/1) and the Wellcome Trust (089703/Z/09/Z). D.P. wishes to acknowledge support from the Swiss National Science Foundation and the Wellcome Trust through personal fellowships. A.K.B thanks Magdalene College, Cambridge and the Leverhulme Trust for support.This is the author accepted manuscript. The final version is available from the National Academy of Sciences via http://dx.doi.org/10.1073/pnas.1516546113

HSV-1 glycoprotein endocytosis

Herpes simplex virus-1 (HSV-1) is a large enveloped DNA virus that belongs to the family of Herpesviridae. It has been recently shown that the cytoplasmic membranes that wrap the newly assembled capsids are endocytic compartments derived from the plasma membrane. Here, we show that dynamin-dependent endocytosis plays a major role in this process. Dominant-negative dynamin and clathrin adaptor AP180 significantly decrease virus production. Moreover, inhibitors targeting dynamin and clathrin lead to a decreased transport of glycoproteins to cytoplasmic capsids, confirming that glycoproteins are delivered to assembly sites via endocytosis. We also show that certain combinations of glycoproteins colocalize with each other and with the components of clathrin-dependent and -independent endocytosis pathways. Importantly, we demonstrate that the uptake of neutralizing antibodies that bind to glycoproteins when they become exposed on the cell surface during virus particle assembly leads to the production of non-infectious HSV-1. Our results demonstrate that transport of viral glycoproteins to the plasma membrane prior to endocytosis is the major route by which these proteins are localized to the cytoplasmic virus assembly compartments. This highlights the importance of endocytosis as a major protein-sorting event during HSV-1 envelopment.This work was supported by grants from the Leverhulme Trust (grant RPG‐2012‐793), the Royal Society (University Research Fellowship UF090010), the Engineering and Physical Sciences Research Council, UK (grant EP/H018301/1, EP/L015889/1) and by the Medical Research Council (grant MR/K015850/1)

Towards Loop Quantum Supergravity (LQSG) II. p-Form Sector

In our companion paper, we focussed on the quantisation of the Rarita-Schwinger sector of Supergravity theories in various dimensions by using an extension of Loop Quantum Gravity to all spacetime dimensions. In this paper, we extend this analysis by considering the quantisation of additional bosonic fields necessary to obtain a complete SUSY multiplet next to graviton and gravitino in various dimensions. As a generic example, we study concretely the quantisation of the 3-index photon of 11d SUGRA, but our methods easily extend to more general p-form fields. Due to the presence of a Chern-Simons term for the 3-index photon, which is due to local SUSY, the theory is self-interacting and its quantisation far from straightforward. Nevertheless, we show that a reduced phase space quantisation with respect to the 3-index photon Gauss constraint is possible. Specifically, the Weyl algebra of observables, which deviates from the usual CCR Weyl algebras by an interesting twist contribution proportional to the level of the Chern-Simons theory, admits a background independent state of the Narnhofer-Thirring type.Comment: 12 pages. v2: Journal version. Minor clarifications and correction

The effect of sublattice symmetry breaking on the electronic properties of a doped graphene

Motivated by a number of recent experimental studies, we have carried out the microscopic calculation of the quasiparticle self-energy and spectral function in a doped graphene when a symmetry breaking of the sublattices is occurred. Our systematic study is based on the many-body G$_0$W approach that is established on the random phase approximation and on graphene's massive Dirac equation continuum model. We report extensive calculations of both the real and imaginary parts of the quasiparticle self-energy in the presence of a gap opening. We also present results for spectral function, renormalized Fermi velocity and band gap renormalization of massive Dirac Fermions over a broad range of electron densities. We further show that the mass generating in graphene washes out the plasmaron peak in spectral weight.Comment: 22 Pages, 10 Figure