Two closely related ureotelic fish species of the genus Alcolapia express different levels of ammonium transporters in gills

Most fish excrete their nitrogenous waste across the gills as ammonia through the activity of the Rhesus glycoprotein ammonium transporters. In contrast, fish of the subgenus Alcolapia (Oreochromis) are the only vertebrates that survive the extreme conditions of the soda lakes of Natron and Magadi in East Africa and have evolved adaptations to the highly alkaline waters including the ability to excrete their nitrogenous waste as urea. Nevertheless, Alcolapia retain the Rhesus glycoprotein genes in their genomes and using two heterologous expression systems, we demonstrate that Alcolapia Rhbg is capable of moving ammonia. Comparing ammonia and urea excretion from two closely related Alcolapia species from the same aquarium, we found that while Alcolapia grahami remains fully ureotelic after many generations in lab conditions, Alcolapia alcalica excretes some of its nitrogenous waste as ammonia. Using in situ hybridisation, we demonstrate robust, localised gene expression of Rhbg, rhcg1 and rhcg2 in the gill tissue in both A. alcalica embryos and adults, similar to that in other ammoniotelic fish. In contrast, the expression of these genes in A. grahami gills is much lower than in A. alcalica, suggesting the rapid evolution of a molecular mechanism underlying the complete ureotelism of A. grahami

Update to the determination of PDFs with ATLAS data: ATLASepWZVjet20

We present a new set of proton parton distribution functions, ATLASepWZVjet20, produced in an analysis at next-to-next-to-leading order in QCD. The new data sets considered are the measurements of $W^+$ and $W^-$ boson and $Z$ boson production in association with jets in $pp$ collisions at $\sqrt{s} = 8~\mathrm{TeV}$ performed by the ATLAS experiment at the LHC with integrated luminosities of $20.2~\mathrm{fb}^{-1}$ and $19.9~\mathrm{fb}^{-1}$, respectively. The analysis also considers the ATLAS measurements of differential $W^{\pm}$ and $Z$ boson production at $\sqrt{s} = 7~\mathrm{TeV}$ with an integrated luminosity of $4.6~\mathrm{fb}^{-1}$ and deep-inelastic-scattering data from $e^{\pm}p$ collisions at the HERA accelerator. An improved determination of the sea-quark densities at high Bjorken $x$ is shown, while confirming a strange-quark density similar in size to the up- and down-sea-quark densities in the range $x \lesssim 0.02$ found by previous ATLAS analyses

QCD analysis and measurement of WW boson production in association with jets at the ATLAS detector

The Standard Model of particle physics stands as one of the triumphs of the20th and 21st century so far. Colliders around the world have been built for thepurpose of pushing this theory to its limit, and have consistently found theirmeasurements to be well described. Yet outside of colliders, there is strongevidence that the Standard Model does not completely describe the universe inwhich we reside. This provides the motivation to continue to push even further,with the hope of resolving these gaping inconsistencies.At this time, many measurements are no longer limited by the power orexperimental precision of our colliders – it is our limited ability to calculatepredictions from the Standard Model which is holding us back. To combatthis, great effort is being undertaken to measure processes which will help us tocalibrate and better understand the finer details of the theory. The production of a W boson in association with jets in proton-protoncollisions serves as a precision test of perturbative quantum chromodynamics, andprovides access to the composition of the proton. In this thesis, a measurementof this process using the ATLAS detector at the LHC for proton-proton collisionsat a centre-of-mass energy of √s = 13 TeV and integrated luminosity of 36.1 fb−1is presented. Results are split by the charge of the W boson and shown for jetmultiplicities up to five in comparison with calculations to next-to-leading order inquantum chromodynamics scaled to the next-to-next-to-leading order cross section.In addition, the results of a similar measurement at a centre-of-mass energy of√s = 8 TeV have been used for the first time in an analysis of the structure of theproton, giving a significantly improved determination of the sea-quark densitiesat medium-to-high Bjorken x compared to other fits of ATLAS data

Observation of WWW Production in pp Collisions at √s = 13 TeV with the ATLAS Detector

This Letter reports the observation of W W W production and a measurement of its cross section using 139     fb − 1 of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. Events with two same-sign leptons (electrons or muons) and at least two jets, as well as events with three charged leptons, are selected. A multivariate technique is then used to discriminate between signal and background events. Events from W W W production are observed with a significance of 8.0 standard deviations, where the expectation is 5.4 standard deviations. The inclusive W W W production cross section is measured to be 820 ± 100   ( stat ) ± 80   ( syst )     fb , approximately 2.6 standard deviations from the predicted cross section of 511 ± 18     fb calculated at next-to-leading-order QCD and leading-order electroweak accuracy