512 research outputs found

    Dinosaur lactation ?

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    Lactation is a process associated with mammals, yet a number of birds feed their newly hatched young on secretions analogous to the milk of mammals. These secretions are produced from various sections (crop organ, oesophageal lining and proventriculus) of the upper digestive tract and possess similar levels of fat and protein, as well as added carotenoids, antibodies and, in the case of pigeons and doves, epidermal growth factor. Parental care in avian species has been proposed to originate from dinosaurs. This study examines the possibility that some dinosaurs used secretory feeding to increase the rate of growth of their young, estimated to be similar to that of present day birds and mammals. Dinosaur \u27lactation\u27 could also have facilitated immune responses as well as extending parental protection as a result of feeding newly hatched young in nest environments. While the arguments for dinosaur lactation are somewhat generic, a case study for lactation in herbivorous site-nesting dinosaurs is presented. It is proposes that secretory feeding could have been used to bridge the gap between hatching and establishment of the normal diet in some dinosaurs

    Prethermal Strong Zero Modes and Topological Qubits

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    We prove that quantum information encoded in some topological excitations, including certain Majorana zero modes, is protected in closed systems for a time scale exponentially long in system parameters. This protection holds even at infinite temperature. At lower temperatures the decay time becomes even longer, with a temperature dependence controlled by an effective gap that is parametrically larger than the actual energy gap of the system. This non-equilibrium dynamical phenomenon is a form of prethermalization, and occurs because of obstructions to the equilibriation of edge or defect degrees of freedom with the bulk. We analyze the ramifications for ordered and topological phases in one, two, and three dimensions, with examples including Majorana and parafermionic zero modes in interacting spin chains. Our results are based on a non-perturbative analysis valid in any dimension, and they are illustrated by numerical simulations in one dimension. We discuss the implications for experiments on quantum-dot chains tuned into a regime supporting end Majorana zero modes, and on trapped ion chains.Comment: 20 pages. v2: reorganized and added overview sectio

    The Macquenoise sandstone : a suitable Lochkovian raw material for ancient millstones : quarries, properties, manufacture and distribution (Belgium-France)

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    International audienceSince a few years a French-Belgian team of archeologists and geologists work on the characterization of ancient quern stones and millstones (mainly from the Antique period) linked with the identification of their stratigraphical and geographical provenances.This fruitful collaboration aims at reconstructing the ancient commercial roads and economic organization of territories during that period.In addition to the better-known volcanic rocks from the Eifel area, our study revealed the frequent occurrence of particular Devonian conglomerates and sandstones from the Ardenne area, as raw materials for the manufacturing of querns and millstones. The latter sandstones as well as the related antique millstone quarries, form an important and until now undervalued geological and cultural heritage in Belgium.Near the Ardenne border between France and Belgium, the earliest Devonian (Lochkovian) sediments deposited on the Caledonian substrate are conglomerates, which are interpreted as continental alluvial fans. The first marine sediments are littoral sandstones/quartzites or shales/slates. A sandstone formation, formally defined as the “Arkose d’Haybes” is closely linked to the former Lochkovian conglomerates (called also the “Poudingue de Fépin”). The outcrops of this particular formation around the reference localities of Haybes, Fépin and Hargnies (Ardennes, France), show a partly recrystallized, well-sorted grey to greenish sandstone (turbidite facies) with wine-red coloured joints. Another important area displaying old quarries in the same formation is located between Hirson (Aisne, France) and Macquenoise (Hainaut, Belgium): here, a more homogenous grey coarse sandstone facies occurs, with a better consistency and small amounts of dark green tourmaline crystals.These detrital formations were locally quarried, not only for building stones but also for the production of querns and millstones. The huge Proto-historical and Roman millstone quarries in Lochkovian conglomerates and sandstones from Macquenoise are known since the 19th century. Even if the lack of recent archeological excavations do not allow yet to precise the exact age of their quarrying, the dating of the various products derived from these quarries allow to consider the duration of the active extraction and how far the millstones from Macquenoise area were transported into the northern Gallo-Roman provinces

    Engrais phosphatés de recyclage - Ce que le secteur bio en pense

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    Le phosphore contenu dans les eaux usées devra être récupéré dès 2026. Qu’en pensent agriculteurs et experts

    Multi-frequency bioimpedance in human muscle assessment

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    Bioimpedance analysis (BIA) is a well-known and tested method for body mass and muscular health assessment. Multi-frequency BIA (mfBIA) equipment now makes it possible to assess a particular muscle as a whole, as well as looking at a muscle at the fiber level. The aim of this study was to test the hypothesis that mfBIA can be used to assess the anatomical, physiological, and metabolic state of skeletal muscles. mfBIA measurements focusing on impedance, resistance, reactance, phase angle, center frequency, membrane capacitance, and both extracellular and intracellular resistance were carried out. Eight healthy human control subjects and three selected cases were examined to demonstrate the extent to which this method may be used clinically, and in relation to training in sport. The electrode setup is shown to affect the mfBIA parameters recorded. Our recommendation is the use of noble metal electrodes in connection with a conductance paste to accommodate the typical BIA frequencies, and to facilitate accurate impedance and resistance measurements. The use of mfBIA parameters, often in conjunction with each other, can be used to reveal indications of contralateral muscle loss, extracellular fluid differences, contracted state, and cell transport/metabolic activity, which relate to muscle performance. Our findings indicate that mfBIA provides a noninvasive, easily measurable and very precise momentary assessment of skeletal muscles

    Rezyklierte Phosphordünger - was die Branche davon hält

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    Phosphor in Abwässern muss ab 2026 rückgewonnen werden. Was halten Landwirte und andere Düngeexperten davon

    Doppelt! Für einen anderen Eintrag verwenden. Rezyklierte Phosphordünger - was die Branche davon hält

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    Phosphor in Abwässern muss ab 2026 rückgewonnen werden. Was halten Landwirte und andere Düngeexperten davon

    Einfluss unterschiedlicher Bewirtschaftungsverfahren auf P-Formen und P-Dynamik im Boden

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    The impact of cropping systems on soil phosphorus (P) forms and P dynamics was studied. The systems were a biodynamic (DYN), a bioorganic (BIO), a conventional (CON), a stockless system (MIN) and an unfertilized control (NON). These cropping systems are part of the DOK field trial in Therwil near Basel. The systems differed in fertilization and plant protection. The P budgets over 30 years were negative except for CON and increased in the order: NON < DYN < ORG < MIN < CON. A sequential P extraction scheme was used to characterize the P forms in soil samples from 2007 and 1977 (before the start of the trial). Labile inorganic P (Pi) forms differed significantly between cropping systems. Organic P forms (Po) and stable Pi forms were not affected by the cropping systems apart from Po in concentrated HCl extract. The comparison between P forms in the soils of 2007 and 1977 revealed depletion in labile Pi forms in all systems. The changes were related to the P budget. Po changes were small and thus most of Po appears to be strongly stabilized in the soil
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