Biogeochemical processes in the active layer and permafrost of a high Arctic fjord valley

Warming of ground is causing microbial decomposition of previously frozen sedimentary organic carbon in Arctic permafrost. However, the heterogeneity of the permafrost landscape and its hydrological processes result in different biogeochemical processes across relatively small scales, with implications for predicting the timing and magnitude of permafrost carbon emissions. The biogeochemical processes of iron- and sulfate-reduction produce carbon dioxide and suppress methanogenesis. Hence, in this study, the biogeochemical processes occurring in the active layer and permafrost of a high Arctic fjord valley in Svalbard are identified from the geochemical and stable isotope analysis of aqueous and particulate fractions in sediment cores collected from ice-wedge polygons with contrasting water content. In the drier polygons, only a small concentration of organic carbon (<5.40 dry weight%) has accumulated. Sediment cores from these drier polygons have aqueous and solid phase chemistries that imply sulfide oxidation coupled to carbonate and silicate dissolution, leading to high concentrations of aqueous iron and sulfate in the pore water profiles. These results are corroborated by δ34S and δ18O values of sulfate in active layer pore waters, which indicate the oxidative weathering of sedimentary pyrite utilising either oxygen or ferric iron as oxidising agents. Conversely, in the sediments of the consistently water-saturated polygons, which contain a high content of organic carbon (up to 45 dry weight%), the formation of pyrite and siderite occurred via the reduction of iron and sulfate. δ34S and δ18O values of sulfate in active layer pore waters from these water-saturated polygons display a strong positive correlation (R2 = 0.98), supporting the importance of sulfate reduction in removing sulfate from the pore water. The significant contrast in the dominant biogeochemical processes between the water-saturated and drier polygons indicates that small-scale hydrological variability between polygons induces large differences in the concentration of organic carbon and in the cycling of iron and sulfur, with ramifications for the decomposition pathway of organic carbon in permafrost environments

A late Eocene age proposal for the Loreto Formation (Brunswick Peninsula, southernmost Chile), based on fossil cartilaginous fishes, paleobotany and radiometric evidence

We present new data on the paleoichthyology, paleobotany and radiometric results of the Loreto Formation in the Brunswick Peninsula of southernmost Chile, that allow us to propose a Late Eocene age. The rich diversity of fossil cartilaginous fishes (Chondrichthyes, Elasmobranchii) recognized in upper levels of this unit includes the taxa Carcharias aff. 'hopei' (Agassiz), Odontaspis sp., Carcharoides catticus (Philippi), Striatolamia macrota (Agassiz), Anomotodon sp., Macrorhizodus praecursor (Leriche), Galeorhinus sp., Abdounia sp., Hexanchus sp., Squatina sp., Hexanchidae indet., Myliobatis sp., Myliobatoidea indet., and Ischyodus dolloi Leriche. This assemblage has clear ecological affinities with Eocene Tethyan fauna previously described in the Northern Hemisphere, and also has common elements with Eocene cartilaginous fishes from Antarctica. Additionally, a paleobotanic study of this unit identified leaf imprints of Asplenium sp., Pteris sp., Podocarpus sp., and abundant angiosperms including Nothofagus lanceolata Dusén, N. simplicidens Dusén, N. variabilis Dusén, N. cf. alessandri Espinosa, N. subferruginea (Dusén), Hydrangea sp. and Phyllites spp. Wood remains of Nothofagoxylon scalariforme Gothan and Araucariaceae cf. Araucarioxylon Kraus were also identified. Additionally, pollen grains indicate gymnosperms and angiosperms: Podocarpidites otagoensis Couper, Retitricolpites sp., Tricolpites sp., Liliacidites sp., Polyporina sp., Nothofagidites cincta Cookson, and Nothofagidites cranwellae Couper, having affinities with Eocene florae, and being consistent with the age of the fossil fishes. Finally, a SHRIMP U-Th-Pb analysis of two samples collected from the studied beds provided thirty-eight and sixty zircon grains, indicating a clear main peak at 36.48±0.47 Ma (MSWD=1.5) and 36,73±0.50 Ma (MSWD=0.65). The integrated results indicate that the upper part of the Loreto Formation has a minimum Priabonian age, supporting previous reassignations of this part of the formation into the Late Eocene, and differing from the Oligocene age proposed in its original definition

The contribution of optimal turbo fan transport aircraft climb schedule to air company economy

Today airlines are challenging two opposite goals: minimization of flight fuel consumption and minimization of elapsed flight time. A well‐known cost structure and cost generators represent significant pre‐conditions for defining cost optimization strategy in an airline company. Airline company management has a limited set of tools for cost managing, which include the following documents: Performance Engineers’ Manual and Aircraft Flight Manual. In this particular paper review we discuss the problem of vertical flight path of turbo‐fan aircraft, where we point out the impact of the choice of climb technique on the overall en route flight profile costs. In temporary aircraft flight preparation process, there is no stressing out the significance of the climb phase in minimizing costs of this particular flight phase. In the paper we show the procedure of defining optimal climbing resulting minimum costs, but also optimal function operational adjustment to the climb schedule. This way of the approximation of optimal function and its adjustment to the operational use enables the application of minimal cost climbing technique in operational use of transportation aircraft. On short‐haul flights, climb phase can reduce cruise flight length up to 60% of total range. In the paper, we show the impact of climb regime on flight profile of turbo‐fan aircraft considering the usage of time, fuel and costs. The impact is shown according to the data taken from the Performance Engineers Manual. The impact stresses the importance of minimum costs climbing regime to cutting down total flight costs. It also shows the conditions which need to be fulfilled in order to apply minimum costs climbing technique. We identify the scope of CAS speed during climb and TOC for flights minimum total expenses by using minimum costs climbing technique. Conditions for achieving minimum costs climbing technique are the results of the logarithmic differential. In order to achieve optimal numerical results we used Newton‐Raphson formula. Santrauka Šiandien oro transporte svarbūs du tikslai: skrydžio metu sunaudojamo kuro mažinimas ir skrydžio laiko trumpinimas. Žinoma kainos struktūra ir kainos komponentės yra reikšmingos išankstinės sąlygos, padedančios sudaryti kainos optimizavimo strategiją oro transporto bendrovėje. Oro transporto bendrovės valdytojai turi ribotą sąnaudų valdymo priemonių komplektą – tai „Priežiūros inžinieriaus vadovas“ ir „Orlaivio skrydžio vadovas“. Straipsnyje aptariama turbosraigtinio lėktuvo vertikalios skrydžio krypties problema, parodomas pasirinktos kilimo technikos poveikis bendrai skrydžio kainai. Dabartiniame lėktuvo ruošimosi skrydžiui procese nėra pabrėžiama kilimo fazės įtaka bendrų skrydžio sąnaudų mažinimui. Straipsnyje pateikiama procedūra, kaip nustatyti optimalų orlaivio kilimą mažiausiomis sąnaudomis, taip pat optimalumo funkcijos korekciją kilimo plane. Optimalumo funkcijos aproksimavimas ir jos naudojimas leidžia taikyti mažiausių sąnaudų kilimo techniką lėktuve. Trumpalaikiuose skrydžiuose kilimo fazė gali sumažinti kruizinio skrydžio trukmę iki 60 proc. Straipsnyje rodoma, kaip lėktuvo kilimo režimas daro poveikį turbosraigtinio lėktuvo skrydžiui laiko, kuro ir sąnaudų požiūriu remiantis duomeni mis, paimtais iš „Priežiūros inžinieriaus vadovo“. Skaičiai rodo, kaip minimalių sąnaudų kilimo režimas sumažina bendrąsias skrydžio sąnaudas. Straipsnyje taip pat atskleidžiamos sąlygos, kurios turi būti vykdytos norint pritaikyti minimalių sąnaudų kilimo techniką. Ją naudojant nustatytas lėktuvo skrydžio greitis ir pakilimo aukštis. Minimalių sąnaudų kilimo technikos sąlygos yra logaritminio diferencialo prendiniai. Optimaliems skaitmeniniams rezultatams gauti panaudota Niutono ir Rapsono formulė. First published online: 21 Oct 2010 Reikšminiai žodžiai: oro bendrovė, ekonomija, transporto lėktuvas, kilimas, techniniai duomenys, optimizavimas, sąnaudos

Hydrogeologic analyses in support of the conceptual model for the LANL Area G LLRW performance assessment

The Los Alamos National Laboratory low level radioactive waste disposal facility at Area G is currently completing a draft of the site Performance Assessment. Results from previous field studies have estimated a range in recharge rate up to 1 cm/yr. Recent estimates of unsaturated hydraulic conductivity for each stratigraphic layer under a unit gradient assumption show a wide range in recharge rate of 10{sup {minus}4} to 1 cm/yr depending upon location. Numerical computations show that a single net infiltration rate at the mesa surface does not match the moisture profile in each stratigraphic layer simultaneously, suggesting local source or sink terms possibly due to surface connected porous regions. The best fit to field data at deeper stratigraphic layers occurs for a net infiltration of about 0.1 cm/yr. A recent detailed analysis evaluated liquid phase vertical moisture flux, based on moisture profiles in several boreholes and van Genuchten fits to the hydraulic properties for each of the stratigraphic units. Results show a near surface infiltration region averages 8m deep, below which is a dry, low moisture content, and low flux region, where liquid phase recharge averages to zero. Analysis shows this low flux region is dominated by vapor movement. Field data from tritium diffusion studies, from pressure fluctuation attenuation studies, and from comparisons of in-situ and core sample permeabilities indicate that the vapor diffusion is enhanced above that expected in the matrix and is presumably due to enhanced flow through the fractures. Below this dry region within the mesa is a moisture spike which analyses show corresponds to a moisture source. The likely physical explanation is seasonal transient infiltration through surface-connected fractures. This anomalous region is being investigated in current field studies, because it is critical in understanding the moisture flux which continues to deeper regions through the unsaturated zone

Hydrogen-Helium Mixtures at High Pressure

The properties of hydrogen-helium mixtures at high pressure are crucial to address important questions about the interior of Giant planets e.g. whether Jupiter has a rocky core and did it emerge via core accretion? Using path integral Monte Carlo simulations, we study the properties of these mixtures as a function of temperature, density and composition. The equation of state is calculated and compared to chemical models. We probe the accuracy of the ideal mixing approximation commonly used in such models. Finally, we discuss the structure of the liquid in terms of pair correlation functions.Comment: Proceedings article of the 5th Conference on Cryocrystals and Quantum Crystals in Wroclaw, Poland, submitted to J. Low. Temp. Phys. (2004

pQCD Physics of multiparton interactions

We study production of two pairs of jets in %hard hadron--hadron collisions in view of extracting contribution of {\em double hard interactions} of three and four partons ($3\to4$, $4\to4$). Such interactions, in spite of being power suppressed at the level of the total cross section, become comparable with the standard hard collisions of two partons, $2\to4$, in the {\em back-to-back kinematics} when the transverse momentum imbalances of two pairing jets are relatively small. We express differential and total cross sections for two-dijet production in double parton collisions through the generalized two-parton distributions, $_2$GPDs \cite{BDFS1}, that contain large-distance two-parton correlations of non-perturbative origin as well as small-distance correlations due to parton evolution. We find that these large- and small-distance correlations participate in different manner in 4-jet production, and treat them in the leading logarithmic approximation of pQCD that resums collinear logarithms in all orders. A special emphasis is given to $3\to4$ double hard interaction processes that occur as an interplay between large- and short-distance parton correlations and were not taken into consideration by approaches inspired by the parton model picture. We demonstrate that the $3\to4$ mechanism, being of the same order in \as as the $4\to4$ process, turns out to be {\em geometrically enhanced} compared to the latter and should contribute significantly to 4-jet production. The framework developed here takes into systematic consideration perturbative $Q^2$ evolution of $_2$GPDs. It can be used as a basis for future analysis of NLO corrections to multi-parton interactions (MPI) at LHC and Tevatron colliders, in particular for improving evaluation of QCD backgrounds to new physics searches.Comment: 16 pages,4 figures Improved presentation; list of references reworked; qualitative estimate of the magnitude of different contributions in the beck-to- back region correcte

Forward Jets and Energy Flow in Hadronic Collisions

We observe that at the Large Hadron Collider, using forward + central detectors, it becomes possible for the first time to carry out calorimetric measurements of the transverse energy flow due to "minijets" accompanying production of two jets separated by a large rapidity interval. We present parton-shower calculations of energy flow observables in a high-energy factorized Monte Carlo framework, designed to take into account QCD logarithmic corrections both in the large rapidity interval and in the hard transverse momentum. Considering events with a forward and a central jet, we examine the energy flow in the interjet region and in the region away from the jets. We discuss the role of these observables to analyze multiple parton collision effects.Comment: 9 pages, 5 figures. Version2: added results on azimuthal distributions and more discussion of energy flow definition using jet clusterin

Azimuthal asymmetries in lepton-pair production at a fixed-target experiment using the LHC beams (AFTER)

A multi-purpose fixed-target experiment using the proton and lead-ion beams of the LHC was recently proposed by Brodsky, Fleuret, Hadjidakis and Lansberg, and here we concentrate our study on some issues related to the spin physics part of this project (referred to as AFTER). We study the nucleon spin structure through $pp$ and $pd$ processes with a fixed-target experiment using the LHC proton beams, for the kinematical region with 7 TeV proton beams at the energy in center-of-mass frame of two nucleons $\sqrt{s}=115$ GeV. We calculate and estimate the $\cos2\phi$ azimuthal asymmetries of unpolarized $pp$ and $pd$ dilepton production processes in the Drell--Yan continuum region and at the $Z$-pole. We also calculate the $\sin(2\phi-\phi_S)$, $\sin(2\phi+\phi_S)$ and $\sin2\phi$ azimuthal asymmetries of $pp$ and $pd$ dilepton production processes with the target proton and deuteron longitudinally or transversally polarized in the Drell--Yan continuum region and around $Z$ resonances region. We conclude that it is feasible to measure these azimuthal asymmetries, consequently the three-dimensional or transverse momentum dependent parton distribution functions (3dPDFs or TMDs), at this new AFTER facility.Comment: 15 pages, 40 figures. Version accepted for publication in EPJ

Mobile inquiry-based learning with sensor-data in the school: Effects on student motivation

The paper discusses the design, implementation and evaluation of a pilot project that integrated inquiry-based learning with mobile game design and introduced mobile devices and sensors into classroom learningweSPOT Project - IST (FP7/2007-2013) under grant agreement N° 318499The project was supported by the SURFnet innovation grant for sustainable ICT solutions