Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Electrochemical Performance and Compatibility of La2NiO4+δ Electrode Material with La0.8Sr0.2Ga0.8Mg0.2O3-δ Electrolyte for Solid Oxide Electrolysis

La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) is an oxygen ion conducting electrolyte material widely used in solid oxide fuel cells (SOFC). La2NiO4+δ (LNO) is a mixed ionic-electronic conducting layered perovskite with K2NiF4 type structure which conducts oxygen ions via oxygen interstitials. LNO has shown promising results as an SOFC electrode in the literature. In this work the compatibility and performance of LNO electrodes on the LSGM electrolyte material for solid oxide electrolysis cell (SOEC) is investigated. The materials were characterised as SOEC/SOFC cells by symmetrical and three electrode electrochemical measurements using Electrochemical Impedance Spectroscopy (EIS). Conductivity and ASR values were obtained in the temperature range 300 – 800oC with varying atmospheres of pH2O and pO2. The cells were also subjected to varied potential bias, mimicking fuel cell or electrolysis use. Enhancement of LNO performance was observed with the application of potential bias in both anodic and cathodic mode of operation in all atmospheres with the exception of cathodic bias in pO2 = 6.5x10-3 atm. In ambient air at 800oC LNO ASRs were 2.82Ω.cm2, 1.83Ω.cm2 and 1.37Ω.cm2 in OCV, +1000mV bias and -1000mV bias respectively. In low pO2 at 800oC LNO ASRs were 9.17Ω.cm2, 1.74Ω.cm2 and 456.9Ω.cm2 in OCV, +1000mV bias and -1000mV bias respectively. The increase in ASR with negative potential bias in low pO2 is believed to be caused by an increase in mass transport and charge transfer impedance responses. Material stability was confirmed using X-Ray Diffraction (XRD), in-situ high temperature pH2O and pO2 XRD. In-situ XRD displayed single phase materials with no observable reactivity in the conditions tested. Scanning Electron Microscopy images of cells tested by EIS in all atmospheres displayed no microstructure degradation except for those cells tested in a humid atmosphere which display a regular pattern of degradation on the LNO surface attributed to reaction with the Pt mesh current collector.Open Acces