Measurement of the π− -Ar total hadronic cross section at the LArIAT experiment

We present the first measurement of the negative pion total hadronic cross section on argon in a restricted phase space, which we performed at the Liquid Argon In ATestbeam (LArIAT) experiment. All hadronic reaction channels, as well as hadronic elastic interactions with scattering angle greater than 5° are included. The pions have kinetic energies in the range 100–700 MeVand are produced by a beam of charged particles impinging on a solid target at the Fermilab test beam facility. LArIAT employs a 0.24 ton active mass liquid argon time projection chamber (LArTPC) to measure the pion hadronic interactions. For this measurement, LArIAT has developed the “thin slice method,” a new technique to measure cross sections with LArTPCs. While moderately higher, our measurement of the π−-Ar total hadronic cross section is generally in agreement with the GEANT4 prediction.Fermi Research Alliance, LLC (FRA) DE-AC02-07CH11359National Science Foundation (NSF)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ) 233511/2014-8Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) 001Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) 16/22738-0Polish National Science Centre 2013/09/N/ST2/02793UK Research & Innovation (UKRI)Science & Technology Facilities Council (STFC)Royal Society of LondonMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science 2510500

The Cambrian of the Iberian Peninsula : an overview

This work is a brief overview of the Cambrian in the Iberian Peninsula, along with an updated review of lithostratigraphic and biostratigraphic data. A Cambrian correlation chart between the different stratigraphical units that have been established in the Iberian Peninsula is given. We also reappraise the Lower and Middle Cambrian regional stages in the light of new palaeontological data, and the different biozonations proposed with several palaeontological groups

A new occurence of the genus Tonkinella in northern Spain and the Middle Cambrian intercontinental correlation

The genus Tonkinella is a typical polimeroid trilobite in lower Middle Cambrian rocks from Vietnam, Canada, U.S.A., India, Korea, Siberia, China and Argentina. It has recently been found in the Mediterranean region (Iberian Chain, northeastern Spain). In this paper we refer the finding of Tonkinella aff. breviceps in the Leonian (lower Middle Cambrian) of the Cantabrian Mountains (northern Spain), analysing its stratigraphical position, fossil assemblages, biochronology and utility for intercontinental correlation. The presence of this taxon allows us to make a more accurate correlation between the Middle Cambrian biochronological scales of Laurentia, the Mediterranean area and China

Stratigraphy of the Cordubian-Ovetian (Lower Cambrian) Transition in the Occidental Iberian Chain (Spain)

[Resumen] Este trabajo analiza los afloramientos de la Formación Embid (Cámbrico Inferior) existentes en el borde nororiental de la Cadena Ibérica Occidental, entre las localidades de Torrijo de la Cañada y Villalengua (unidad estructural de Moros). Con este objetivo se han realizado dos perfiles estratigráficos y estudiado sus litofacies. Asimismo, se pone de manifiesto el contenido paleoicnológico más representativo. La aparición de distintos ejemplares del icnogénero Astropolichnus separados 200 m. en la serie estratigráfica plantea la necesidad de reconsiderar la precisión de este incofósil como indicador bioestratigráfico. Debido a la ausencia de afloramientos superficiales de la Formación Bámbola, estos materiales constituyen las rocas más antiguas.de esta Cadena. Finalmente, se propone al perfil To1 como hipoestratotipo de la Formación Embid en la Cadena Ibérica Occidental.[Abstract] This work presents a study of the Embid Formation, the oldest formation cropped out in the Occidental Iberian Chain (NE Spain). This outcrop is placed in the nucleus of the Moros structural unit (ALVARO et al., 1992), located in the nonheastern contact of this Chain with the Calatayud-Teruel Teniary basin, between Villalengua and Torrijo de la Cañada localities (Zaragoza Province). We have studied two sections of the Embid Formation (To1 and T02). The first one, 250 m. thick, is the most complete and shows the best exposition of the area. It is proposed as the hipostratotype of the Embid Formation in this Chain. In To1, four terms (El to E4) of this formation and other at the beginning of the Jalón Formation al) have been recognized, according to the sandstone/shale ratio. The ichnofossils and other sedimentary structures studied here suggest, for terms E2 and E4-J1, a litoral to shallow sublitoral environment (tidal flat and tidal channels, influenced by tidal and wave effects), and a sublitoral (circalitoral) environment with episodic levels influenced by storms currents and/or hard tides, for the terms El and E3. The northeastwards To2 section, 150 m. thick, shows a similar evolution, but a more distal character. The wide development of subtidal sand bodies as well as the low diversity and wealth of biogenic structures, suggest a shoreface sedimentation, with a intercalated episode influenced by tidal action. The materials of this section are assigned to the Embid Formation for its lithology, the lack of white quarzites (that characterize the underlying Bámbola Formation) and the ichnofossil record. In spite of palichnological, lithological and sedjmentological affinities between both profils, we can not give an accurate correlation of both sequences. The section To1 records a shallower episode (E2), reaching subaerial exposure in the Cordubian-Ovetian transition. It is the first time this episode has been recognized in the Iberian Chains, and it is considered as a local process. A second shallower episode is placed in the transition of the Embid-Jalón Formations (E4-J1). It has been recognized in other outcrops of the Iberian Chains and LIÑAN & GAMEZ (in press) have proposed a correlation of this regressive episode with the Woodlands Regression (BRASIER, 1985). On the other hand, Astropolichnus ichnogenus is recorded in different levels of same section (200 m. separated), for the first-time in the Iberian Chains. This fact will force to reconsider the accuracy of this ichnofossil as biostratigraphical marker. Finally, a progresive eastwards distallity of the sediments is inferred by comparison with similar outcrops of the Oriental Iberian Chain, by the existence of the first local"shallower episode, placed in the more suroccidental outcrop of the basin (To1), and by the northeastwards paleocurrents directions. These data support the existence of an emerged area beside the occidental margin of the Cantabrian-Iberian Basin as was pointed by LOTZE (1961), and also proposed in the cantabrian sector of this basin by ARAMBURU el al. (1992)

Поверхностные скорости и айсберговый сток ледникового купола Академии Наук на Северной Земле

We have determined the ice-surface velocities of the Academy of Sciences Ice Cap, Severnaya Zemlya, Russian Arctic, during the period November 2016 – November 2017, using intensity offset-tracking of Sentinel-1 synthetic-aperture radar images. We used the average of 54 pairs of weekly velocities (with both images in each pair separated by a12-day period) to estimate the mean annual ice discharge from the ice cap. We got an average ice discharge for 2016–2017 of 1,93±0,12 Gt a−1, which is equivalent to −0,35±0,02 m w.e. a−1 over the whole area of the ice cap. The difference from an estimate of ~1,4 Gt a−1 for 2003–2009 can be attributed to the initiation of ice-stream flow in Basin BC sometime between 2002 and 2016. Since the front position changes between both periods have been negligible, ice discharge is equivalent to calving flux. We compare our results for calving flux with those of previous studies and analyse the possible drivers of the changes observed along the last three decades. Since these changes do not appear to have responded to environmental changes, we conclude that the observed changes are likely driven by the intrinsic characteristics of the ice cap governing tidewater glacier dynamics.По 54 парам космических снимков Sentinel‐1, сделанных с ноября 2016 г. по ноябрь 2017 г., определены скорости движения ледникового купола Академии Наук на Северной Земле. На этой основе оценён среднегодовой расход льда в море этого купола (1,93±0,12 Гт/год), установлены основные пути стока льда, проведено сравнение с прежними оценками

Quorum sensing as a mechanism to harness the wisdom of the crowds

Bacteria release and sense small molecules called autoinducers in a process known as quorum sensing. The prevailing interpretation of quorum sensing is that by sensing autoinducer concentrations, bacteria estimate population density to regulate the expression of functions that are only beneficial when carried out by a sufficiently large number of cells. However, a major challenge to this interpretation is that the concentration of autoinducers strongly depends on the environment, often rendering autoinducer-based estimates of cell density unreliable. Here we propose an alternative interpretation of quorum sensing, where bacteria, by releasing and sensing autoinducers, harness social interactions to sense the environment as a collective. Using a computational model we show that this functionality can explain the evolution of quorum sensing and arises from individuals improving their estimation accuracy by pooling many imperfect estimates – analogous to the ‘wisdom of the crowds’ in decision theory. Importantly, our model reconciles the observed dependence of quorum sensing on both population density and the environment and explains why several quorum sensing systems regulate the production of private goods.</p