Twistor spaces for HKT manifolds

We construct the twistor space associated with an HKT manifold, that is, a hyper-K\"ahler manifold with torsion, a type of geometry that arises as the target space geometry in two-dimensional sigma models with (4,0) supersymmetry. We show that this twistor space has a natural complex structure and is a holomorphic fibre bundle over the complex projective line with fibre the associated HKT manifold. We also show how the metric and torsion of the HKT manifold can be determined from data on the twistor space by a reconstruction theorem. We give a geometric description of the sigma model (4,0) superfields as holomorphic maps (suitably understood) from a twistorial extension of (4,0) superspace (harmonic superspace) into the twistor space of the sigma model target manifold and write an action for the sigma model in terms of these (4,0) superfields.Comment: 15 pages, Phyzz

Reentrant spin glass behavior in a layered manganite La1.2Sr1.8Mn2O7 single crystals

We report here a detailed study of AC/DC magnetization and longitudinal/transverse transport properties of La$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$ single crystals below $T_{c}$ = 121 K. We find that the resistivity upturn below 40 K is related to the reentrant spin glass phase at the same temperature, accompanied by additional anomalous Hall effects. The carrier concentration from the ordinary Hall effects remains constant during the transition and is close to the nominal doping level (0.4 holes/Mn). The spin glass behavior comes from the competition between ferromagnetic double exchange and antiferromagnetic superexchange interactions, which leads to phase separation, i.e. a mixture of ferromagnetic and antiferromagnetic clusters, representing the canted antiferromagnetic state.Comment: 5 pages, 5 figures, submitted to Phys. Rev.

A 2k2k-Vertex Kernel for Maximum Internal Spanning Tree

We consider the parameterized version of the maximum internal spanning tree problem, which, given an $n$-vertex graph and a parameter $k$, asks for a spanning tree with at least $k$ internal vertices. Fomin et al. [J. Comput. System Sci., 79:1-6] crafted a very ingenious reduction rule, and showed that a simple application of this rule is sufficient to yield a $3k$-vertex kernel. Here we propose a novel way to use the same reduction rule, resulting in an improved $2k$-vertex kernel. Our algorithm applies first a greedy procedure consisting of a sequence of local exchange operations, which ends with a local-optimal spanning tree, and then uses this special tree to find a reducible structure. As a corollary of our kernel, we obtain a deterministic algorithm for the problem running in time $4^k \cdot n^{O(1)}$

Potential impacts of a Turkish EU-membership on agri-food markets

This paper examines possible impacts of a Turkish accession to the EU on the agricultural markets in Turkey and the EU. AGMEMOD, an econometric, dynamic, multi-market, partial equilibrium economic model for EU agriculture at Member State level, has been extended with a model for the Turkish agricultural sector and afterwards applied to gain quantitative insights into Turkish accession effects. To establish a model for Turkey, the implementation of the model equations required parameter estimates, or the specification of synthetic model parameters. A database with time series on Turkish agricultural production, market balances and prices, macroeconomic variables and policy variables was developed in order to estimate such model parameters and to build an operational Turkish agriculture sector model. Most results show that the dominant impact of the Turkish accession on Turkish agriculture is a reduction of domestic producer prices, which induces further market effects. The - mostly decoupled - CAP support payments will induce smaller incentives to increase production than those which Turkish farmers receive prior to the EU accession. In Turkey effects of accession to the EU will be mostly negative for crop producers (except for tobacco), whereas the consumers are expected to gain from lower market prices. In contrast, producers of sheep meat, broiler and dairy milk could gain from an accession due to lower feed costs

Computer-aided Melody Note Transcription Using the Tony Software: Accuracy and Efficiency

accepteddate-added: 2015-05-24 19:18:46 +0000 date-modified: 2017-12-28 10:36:36 +0000 keywords: Tony, melody, note, transcription, open source software bdsk-url-1: https://code.soundsoftware.ac.uk/attachments/download/1423/tony-paper_preprint.pdfdate-added: 2015-05-24 19:18:46 +0000 date-modified: 2017-12-28 10:36:36 +0000 keywords: Tony, melody, note, transcription, open source software bdsk-url-1: https://code.soundsoftware.ac.uk/attachments/download/1423/tony-paper_preprint.pdfWe present Tony, a software tool for the interactive an- notation of melodies from monophonic audio recordings, and evaluate its usability and the accuracy of its note extraction method. The scientific study of acoustic performances of melodies, whether sung or played, requires the accurate transcription of notes and pitches. To achieve the desired transcription accuracy for a particular application, researchers manually correct results obtained by automatic methods. Tony is an interactive tool directly aimed at making this correction task efficient. It provides (a) state-of-the art algorithms for pitch and note estimation, (b) visual and auditory feedback for easy error-spotting, (c) an intelligent graphical user interface through which the user can rapidly correct estimation errors, (d) extensive export functions enabling further processing in other applications. We show that Tony’s built in automatic note transcription method compares favourably with existing tools. We report how long it takes to annotate recordings on a set of 96 solo vocal recordings and study the effect of piece, the number of edits made and the annotator’s increasing mastery of the software. Tony is Open Source software, with source code and compiled binaries for Windows, Mac OS X and Linux available from https://code.soundsoftware.ac.uk/projects/tony/

Antibound poles in cutoff Woods-Saxon and in Salamon-Vertse potentials

The motion of l=0 antibound poles of the S-matrix with varying potential strength is calculated in a cutoff Woods-Saxon (WS) potential and in the Salamon-Vertse (SV) potential, which goes to zero smoothly at a finite distance. The pole position of the antibound states as well as of the resonances depend on the cutoff radius, especially for higher node numbers. The starting points (at potential zero) of the pole trajectories correlate well with the range of the potential. The normalized antibound radial wave functions on the imaginary k-axis below and above the coalescence point have been found to be real and imaginary, respectively

APENet: LQCD clusters a la APE

Developed by the APE group, APENet is a new high speed, low latency, 3-dimensional interconnect architecture optimized for PC clusters running LQCD-like numerical applications. The hardware implementation is based on a single PCI-X 133MHz network interface card hosting six indipendent bi-directional channels with a peak bandwidth of 676 MB/s each direction. We discuss preliminary benchmark results showing exciting performances similar or better than those found in high-end commercial network systems.Comment: Lattice2004(machines), 3 pages, 4 figure

FARS2 mutations presenting with pure spastic paraplegia and lesions of the dentate nuclei.

Mutations in FARS2, the gene encoding the mitochondrial phenylalanine-tRNA synthetase (mtPheRS), have been linked to a range of phenotypes including epileptic encephalopathy, developmental delay, and motor dysfunction. We report a 9-year-old boy with novel compound heterozygous variants of FARS2, presenting with a pure spastic paraplegia syndrome associated with bilateral signal abnormalities in the dentate nuclei. Exome sequencing identified a paternal nonsense variant (Q216X) lacking the catalytic core and anticodon-binding regions, and a maternal missense variant (P136H) possessing partial enzymatic activity. This case confirms and expands the phenotype related to FARS2 mutations with regards to clinical presentation and neuroimaging findings

Measurement of ultra‐heavy cosmic rays at a lunar base

A wealth of information regarding cosmic ray synthesis and propagation is contained in the ultra‐heavy (Z≳60) cosmic ray abundances; to extract this information, however, requires a detector capable of acquiring large statistics for these rare particles, as well as a charge resolution adequate to separate neighboring charge peaks at very large Z. A large, passive surface array of nuclear‐track‐detecting glass plates would meet these requirements. These glass plates could be periodically processe and analyzed for tracks at a lunar base, then melted/annealed for reuse in a continuously recycled detector array.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87613/2/42_1.pd