Hole Superconductivity in MgB2Mg B_2: a high TcT_c cuprate without Cu

The theory of hole superconductivity explains high temperature superconductivity in cuprates as driven by pairing of hole carriers in oxygen $p\pi$ orbitals in the highly negatively charged $Cu-O$ planes. The pairing mechanism is hole undressing and is Coulomb-interaction driven. We propose that the planes of $B$ atoms in $Mg B_2$ are akin to the $Cu-O$ planes without $Cu$, and that the recently observed high temperature superconductivity in $Mg B_2$ arises similarly from undressing of hole carriers in the planar boron $p_{x,y}$ orbitals in the negatively charged $B^-$ planes. Doping $Mg B_2$ with electrons and with holes should mirror the behavior of underdoped and overdoped high $T_c$ cuprates respectively. We discuss possible ways to achieve higher transition temperatures in boron compounds based on this theory.Comment: A section on isotope effect has been added, as well as other minor change

Automatic Estimation of Modulation Transfer Functions

The modulation transfer function (MTF) is widely used to characterise the performance of optical systems. Measuring it is costly and it is thus rarely available for a given lens specimen. Instead, MTFs based on simulations or, at best, MTFs measured on other specimens of the same lens are used. Fortunately, images recorded through an optical system contain ample information about its MTF, only that it is confounded with the statistics of the images. This work presents a method to estimate the MTF of camera lens systems directly from photographs, without the need for expensive equipment. We use a custom grid display to accurately measure the point response of lenses to acquire ground truth training data. We then use the same lenses to record natural images and employ a data-driven supervised learning approach using a convolutional neural network to estimate the MTF on small image patches, aggregating the information into MTF charts over the entire field of view. It generalises to unseen lenses and can be applied for single photographs, with the performance improving if multiple photographs are available

Towards an understanding of hole superconductivity

From the very beginning K. Alex M\"uller emphasized that the materials he and George Bednorz discovered in 1986 were $hole$ superconductors. Here I would like to share with him and others what I believe to be $the$ key reason for why high $T_c$ cuprates as well as all other superconductors are hole superconductors, which I only came to understand a few months ago. This paper is dedicated to Alex M\"uller on the occasion of his 90th birthday.Comment: Dedicated to Alex M\"uller on the Occasion of his 90th Birthday. arXiv admin note: text overlap with arXiv:1703.0977

Non-native populations of an invasive tree outperform their native conspecifics

Introduced plants often face new environmental conditions in their non-native ranges. To become invasive, they need to overcome several biotic and abiotic filters that may trigger adaptive changes in life-history traits, like postgermination processes. Such early life cycle traits may play a crucial role in the colonization and establishment success of invasive plants. As a previous study revealed that seeds of non-native populations of the woody Siberian elm, Ulmus pumila, germinated faster than those of native populations, we expected growth performance of seedlings to mirror this finding. Here, we conducted a common garden greenhouse experiment using different temperature and watering treatments to compare the biomass production of U. pumila seedlings derived from 7 native and 13 populations from two non-native ranges. Our results showed that under all treatments, non-native populations were characterized by higher biomass production and enhanced resource allocation to aboveground biomass compared to the native populations. The observed enhanced growth performance of non-native populations might be one of the contributing factors for the invasion success of U. pumila due to competitive advantages during the colonization of new sites.Fil: Hirsch, Heidi. Stellenbosch University, Centre for Invasion Biology, Department of Botany and Zoology; Sudáfrica. Martin Luther University Halle-Wittenberg, Institute of Biology/Geobotany and Botanical Garden ; AlemaniaFil: Hensen, Isabell. Martin Luther University Halle-Wittenberg, Institute of Biology/Geobotany and Botanical Garden ; Alemania. German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; AlemaniaFil: Wesche, Karsten. German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; Alemania. Senckenberg Museum of Natural History Goerlitz; AlemaniaFil: Renison, Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; ArgentinaFil: Wypior, Catherina. Martin Luther University Halle-Wittenberg, Institute of Biology/Geobotany and Botanical Garden ; AlemaniaFil: Hartmann, Matthias. Charles University in Prague, Herbarium PRC & Department of Botany; República ChecaFil: von Wehrden, Henrik. Leuphana University, Institute of Ecology/Faculty of Sustainability, Centre of Methods; Alemania. Research Institute of Wildlife Ecology; Austri

pep2pro: the high-throughput proteomics data processing, analysis, and visualization tool

The pep2pro database was built to support effective high-throughput proteome data analysis. Its database schema allows the coherent integration of search results from different database-dependent search algorithms and filtering of the data including control for unambiguous assignment of peptides to proteins. The capacity of the pep2pro database has been exploited in data analysis of various Arabidopsis proteome datasets. The diversity of the datasets and the associated scientific questions required thorough querying of the data. This was supported by the relational format structure of the data that links all information on the sample, spectrum, search database, and algorithm to peptide and protein identifications and their post-translational modifications. After publication of datasets they are made available on the pep2pro website at www.pep2pro.ethz.ch. Further, the pep2pro data analysis pipeline also handles data export do the PRIDE database (http://www.ebi.ac.uk/pride) and data retrieval by the MASCP Gator (http://gator.masc-proteomics.org/). The utility of pep2pro will continue to be used for analysis of additional datasets and as a data warehouse. The capacity of the pep2pro database for proteome data analysis has now also been made publicly available through the release of pep2pro4all, which consists of a database schema and a script that will populate the database with mass spectrometry data provided in mzIdentML format

A Microfluidic Approach to Investigate the Contact Force Needed for Successful Contact-Mediated Nucleation

Emulsions with crystalline dispersed phase fractions are becoming increasingly important in the pharmaceutical, chemical, and life science industries. They can be produced by using two-stage melt emulsification processes. The completeness of the crystallization step is of particular importance as it influences the properties, quality, and shelf life of the products. Subcooled, liquid droplets in agitated vessels may contact an already crystallized particle, leading to so-called contact-mediated nucleation (CMN). Energetically, CMN is a more favorable mechanism than spontaneous nucleation. The CMN happens regularly because melt emulsions are stirred during production and storage. It is assumed that three main factors influence the efficiency of CNM, those being collision frequency, contact time, and contact force. Not all contacts lead to successful nucleation of the liquid droplet, therefore, we used microfluidic experiments with inline measurements of the differential pressure to investigate the minimum contact force needed for successful nucleation. Numerical simulations were performed to support the experimental data obtained. We were able to show that the minimum contact force needed for CMN increases with increasing surfactant concentration in the aqueous phase

PlantDB – a versatile database for managing plant research

Background Research in plant science laboratories often involves usage of many different species, cultivars, ecotypes, mutants, alleles or transgenic lines. This creates a great challenge to keep track of the identity of experimental plants and stored samples or seeds. Results Here, we describe PlantDB – a Microsoft® Office Access database – with a user-friendly front-end for managing information relevant for experimental plants. PlantDB can hold information about plants of different species, cultivars or genetic composition. Introduction of a concise identifier system allows easy generation of pedigree trees. In addition, all information about any experimental plant – from growth conditions and dates over extracted samples such as RNA to files containing images of the plants – can be linked unequivocally. Conclusion We have been using PlantDB for several years in our laboratory and found that it greatly facilitates access to relevant information.ISSN:1746-481

Targeting the IspD Enzyme in the MEP Pathway: Identification of a Novel Fragment Class

The enzymes of the 2-C-methylerythritol-d-erythritol 4-phosphate (MEP) pathway (MEP pathway or non-mevalonate pathway) are responsible for the synthesis of universal precursors of the large and structurally diverse family of isoprenoids. This pathway is absent in humans, but present in many pathogenic organisms and plants, making it an attractive source of drug targets. Here, we present a high-throughput screening approach that led to the discovery of a novel fragment hit active against the third enzyme of the MEP pathway, PfIspD. A systematic SAR investigation afforded a novel chemical structure with a balanced activity–stability profile (16). Using a homology model of PfIspD, we proposed a putative binding mode for our newly identified inhibitors that sets the stage for structure-guided optimization

Loose powder detection and surface characterization in selective laser sintering via optical coherence tomography

Defects produced during selective laser sintering (SLS) are difficult to non-destructively detect after build completion without the use of X-ray-based methods. Overcoming this issue by assessing integrity on a layer-by-layer basis has become an area of significant interest for users of SLS apparatus. Optical coherence tomography (OCT) is used in this study to detect surface texture and sub-surface powder, which is un-melted/insufficiently sintered, is known to be a common cause of poor part integrity and would prevent the use of SLS where applications dictate assurance of defect-free parts. To demonstrate the capability of the instrument and associated data-processing algorithms, samples were built with graduated porosities which were embedded in fully dense regions in order to simulate defective regions. Simulated in situ measurements were then correlated with the process parameters used to generate variable density regions. Using this method, it is possible to detect loose powder and differentiate between densities of ±5% at a sub-surface depth of approximately 300 μm. In order to demonstrate the value of OCT as a surface-profiling technique, surface texture datasets are compared with focus variation microscopy. Comparable results are achieved after a spatial bandwidth- matching procedure