The 2dF QSO Redshift Survey - V. The 10k catalogue

We present a catalogue comprising over 10 000 QSOs covering an effective area of 289.6 deg2, based on spectroscopic observations with the 2-degree Field (2dF) instrument at the Anglo-Australian Telescope. This catalogue forms the first release of the 2dF QSO Redshift Survey. QSO candidates with 18.2

Sinuous ridges and the history of fluvial and glaciofluvial activity in Chukhung Crater, Tempe Terra, Mars

International audience<p>We explore the origins of a complex assemblage of sinuous ridges in Chukhung crater (38.47°N, 72.42°W), Tempe Terra, Mars, and discuss the implications of the landsystem for post-Noachian fluvial and glaciofluvial activity in this location [1].</p><p>We produced a geomorphic map of Chukhung crater using a basemap of 6 m/pixel Context Camera (CTX) images and a 75 m/pixel High Resolution Stereo Camera digital elevation model (DEM). We used 25 cm/pixel High Resolution Imaging Science Experiment images, and a 24 cm/pixel DEM generated from CTX stereopair images [2] to aid classifications of sinuous ridges into four morpho-stratigraphic subtypes. We constrained an age envelope of ~2.1–3.6 Ga for Chukhung crater using modelled ages (from crater size-frequency analyses) of units above and below it in the regional stratigraphy. We derived a minimum model age of ~330 Ma for viscous flow features (putative debris-covered glaciers) in southern Chukhung crater.</p><p>Sinuous ridges in southern Chukhung crater emerge from moraine-like deposits associated with the debris-covered glaciers. Sinuous ridges in northern Chukhung crater extend from dendritic fluvial valley networks on the crater wall. The northern sinuous ridges are most likely to be inverted palaeochannels, which comprise subaerial river sediments exhumed as ridges by erosion of surrounding materials.</p><p>Both sinuous ridge subtypes in southern Chukhung crater have numerous esker-like properties. Eskers are ridges of glaciofluvial sediment deposited in meltwater tunnels within or beneath glacial ice. One of the ridge subtypes in southern Chukhung crater is best explained as eskers because these ridges ascend the sides of their host valleys and, in places, escape over them onto adjacent plains. Post-depositional processes can cause inverted paleochannels to cross local undulations in the contemporary topography [3] but the ascent and escape over larger, pre-existing topographic divides is (as yet) not adequately explained by these mechanisms. Eskers, in contrast, form under hydraulic pressure in ice-confined tunnels, and commonly ascend valley walls and cross topographic divides. The esker-like properties of the second sinuous ridge subtype in southern Chukhung crater can also be explained under the inverted palaeochannel hypothesis so the origins of these ridges remain more ambiguous.</p><p>Chukhung crater has undergone protracted and/or episodic modification by liquid water since its formation between the early Hesperian and early Amazonian. This falls after the Noachian period (>3.7 Ga), when most major fluvial activity on Mars occurred. Esker-forming wet-based glaciation in Chukhung crater might have occurred as recently as the mid Amazonian (>330 Ma), when climate conditions are thought to have been cold and hyper-arid. Rare occurrences of eskers associated with Amazonian-aged glaciers in Mars’ mid-latitudes are attributed to transient, localised geothermal heating within tectonic rift/graben settings [4]. The location of Chukhung crater between major branches of the large Tempe Fossae volcano-tectonic rift system is consistent with this hypothesis.</p><p>References: [1] Butcher et al. 2021, Icarus 357, 114131. [2] Mayer and Kite 2016, Lunar Planet. Sci. Conf. Abstract #1241. [3] Lefort et al. 2012, J. Geophys. Res. Planets 117, E03007. [4] Butcher et al. 2017, J. Geophys. Res. Planets 122, 2445–2468.</p&gt

Eskers associated with buried glaciers in Mars' mid latitudes: recent advances and future directions

Until recently, the influence of basal liquid water on the evolution of buried glaciers in Mars' mid latitudes was assumed to be negligible because the latter stages of Mars' Amazonian period (3 Ga to present) have long been thought to have been similarly cold and dry to today. Recent identifications of several landforms interpreted as eskers associated with these young (100s Ma) glaciers calls this assumption into doubt. They indicate basal melting (at least locally and transiently) of their parent glaciers. Although rare, they demonstrate a more complex mid-to-late Amazonian environment than was previously understood. Here, we discuss several open questions posed by the existence of glacier-linked eskers on Mars, including on their global-scale abundance and distribution, the drivers and dynamics of melting and drainage, and the fate of meltwater upon reaching the ice margin. Such questions provide rich opportunities for collaboration between the Mars and Earth cryosphere research communities

Global Search for New Physics with 2.0/fb at CDF

Data collected in Run II of the Fermilab Tevatron are searched for indications of new electroweak-scale physics. Rather than focusing on particular new physics scenarios, CDF data are analyzed for discrepancies with the standard model prediction. A model-independent approach (Vista) considers gross features of the data, and is sensitive to new large cross-section physics. Further sensitivity to new physics is provided by two additional algorithms: a Bump Hunter searches invariant mass distributions for "bumps" that could indicate resonant production of new particles; and the Sleuth procedure scans for data excesses at large summed transverse momentum. This combined global search for new physics in 2.0/fb of ppbar collisions at sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D Rapid Communication

Observation of Orbitally Excited B_s Mesons

We report the first observation of two narrow resonances consistent with states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+, \bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1}) = 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let

Disgust sensitivity relates to attitudes toward gay men and lesbian women across 31 nations

Previous work has reported a relation between pathogen-avoidance motivations and prejudice toward various social groups, including gay men and lesbian women. It is currently unknown whether this association is present across cultures, or specific to North America. Analyses of survey data from adult heterosexuals (N = 11,200) from 31 countries showed a small relation between pathogen disgust sensitivity (an individual-difference measure of pathogen-avoidance motivations) and measures of antigay attitudes. Analyses also showed that pathogen disgust sensitivity relates not only to antipathy toward gay men and lesbians, but also to negativity toward other groups, in particular those associated with violations of traditional sexual norms (e.g., prostitutes). These results suggest that the association between pathogen-avoidance motivations and antigay attitudes is relatively stable across cultures and is a manifestation of a more general relation between pathogen-avoidance motivations and prejudice towards groups associated with sexual norm violations

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02