846 research outputs found

    Biological aspects of an interesting fossil fish: <i>Paramblypterus duvernoyi</i> (Amblypteridae, Actinopterygii)

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    Based on three-dimensional models of the skull and body of Paramblypterus duvernoyi, function of the feeding apparatus and potential of locomotion are interpreted. Compared to most other lower actinopterygians, certain modified features regarding the suspensory apparatus, snout bones, gape, dermohyal and suborbital region, and palaloquadrate-maxillary chamber, are present in P. duvernyoi. These features suggest an increased versatility of the skull and/or enlargement of underlying muscles, thus improving the ability of food uptake. The weak, pin-like teeth present in P. duvernoyi suggest a main diet of small or soft-bodied planktonic or benthic invertebrate organisms. Axial locomotion of P. duvernoyi appears to lie within the range of moderate swimming speeds. P. duvernoyi probably had a flat belly indicating that this species lived close to the bottom. Anhand drei-dimensionaler Modelle des Schädels und Körpers von Paramblypterus duvernoyi werden Funktionsweise des Ernährungsapparates und Möglichkeiten der Fortbewegung interpretiert. Im Vergleich mit anderen basalen Actinopterygiern erscheint die Schädelrekonstruktion von P. duvernoyi hinsichtlich des Suspensoriums. der Schnauzenknochen, der Mundöffnung, des Dermohyal- und Suborbitalbereiches, sowie der Palatoquadratum-Maxillare-Kammer abgeleitet. Dies deutet auf eine erhöhte Beweglichkeit in diesen Bereichen und/oder eine Vergrößerung der darunter liegenden Muskeln hin, was vorteilhaft für die Nahrungsaufnahme ist. Die schmalen, stiftförmigen Zähne von P. duvernoyi deuten auf eine Ernährung von kleineren oder weichkörperigen benthischen und planktischen Invertebraten hin. Vermutlich zeichnete sich die axiale Fortbewegungsweise von Paramblypterus durch mäßige mittlere Schwimmgeschwindigkeit aus. Der Bauch von P. duvernoyi war wahrscheinlich abgeflacht, was darauf hinweist, dass diese Art bodenbezogen gelebt hat. doi:10.1002/mmng.20010040109</a

    Quadrupole transitions and quantum gates protected by continuous dynamic decoupling

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    Dynamical decoupling techniques are a versatile tool for engineering quantum states with tailored properties. In trapped ions, nested layers of continuous dynamical decoupling (CDD) by means of radio-frequency field dressing can cancel dominant magnetic and electric shifts and therefore provide highly prolonged coherence times of electronic states. Exploiting this enhancement for frequency metrology, quantum simulation or quantum computation, poses the challenge to combine the decoupling with laser-ion interactions for the quantum control of electronic and motional states of trapped ions. Ultimately, this will require running quantum gates on qubits from dressed decoupled states. We provide here a compact representation of nested CDD in trapped ions, and apply it to electronic S and D states and optical quadrupole transitions. Our treatment provides all effective transition frequencies and Rabi rates, as well as the effective selection rules of these transitions. On this basis, we discuss the possibility of combining CDD and Mølmer-Sørensen gates

    Improving the monitoring of deciduous broadleaf phenology using the Geostationary Operational Environmental Satellite (GOES) 16 and 17

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    Monitoring leaf phenology allows for tracking the progression of climate change and seasonal variations in a variety of organismal and ecosystem processes. Networks of finite-scale remote sensing, such as the PhenoCam Network, provide valuable information on phenological state at high temporal resolution, but have limited coverage. To more broadly remotely sense phenology, satellite-based data that has lower temporal resolution has primarily been used (e.g., 16-day MODIS NDVI 10 product). Recent versions of the Geostationary Operational Environmental Satellites (GOES-16 and -17) allow the monitoring of NDVI at temporal scales comparable to that of PhenoCam throughout most of the western hemisphere. Here we examine the current capacity of this new data to measure the phenology of deciduous broadleaf forests for the first two full calendar years of data (2018 and 2019) by fitting double-logistic Bayesian models and comparing the start, middle, and end of season transition dates to those obtained from PhenoCam and MODIS 16-day NDVI and EVI products. Compared to the MODIS 15 indices, GOES was more correlated with PhenoCam at the start and middle of spring, but had a larger bias (3.35 ± 0.03 days later than PhenoCam) at the end of spring. Satellite-based autumn transition dates were mostly uncorrelated with those of PhenoCam. PhenoCam data produced significantly more certain (all p-values £ 0.013) estimates of all transition dates than any of the satellite sources did. GOES transition date uncertainties were significantly smaller than those of MODIS EVI for all transition dates (all p-values £ 0.026), but were only smaller (based on p-value < 0.05) than those from MODIS NDVI for 20 the beginning and middle of spring estimates. GOES will improve the monitoring of phenology at large spatial coverages and is able to provide real-time indicators of phenological change even for spring transitions that might occur within the 16-day resolution of these MODIS products.https://doi.org/10.5194/bg-2020-30

    CEP-stable Tunable THz-Emission Originating from Laser-Waveform-Controlled Sub-Cycle Plasma-Electron Bursts

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    We study THz-emission from a plasma driven by an incommensurate-frequency two-colour laser field. A semi-classical transient electron current model is derived from a fully quantum-mechanical description of the emission process in terms of sub-cycle field-ionization followed by continuum-continuum electron transitions. For the experiment, a CEP-locked laser and a near-degenerate optical parametric amplifier are used to produce two-colour pulses that consist of the fundamental and its near-half frequency. By choosing two incommensurate frequencies, the frequency of the CEP-stable THz-emission can be continuously tuned into the mid-IR range. This measured frequency dependence of the THz-emission is found to be consistent with the semi-classical transient electron current model, similar to the Brunel mechanism of harmonic generation

    Integrated on-chip mass spectrometry reaction monitoring in microfluidic devices containing porous polymer monolithic columns

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    Chip-based microfluidics enable the seamless integration of different functions into single devices. Here, we present microfluidic chips containing porous polymer monolithic columns as a means to facilitate chemical transformations as well as both downstream chromatographic separation and mass spectrometric analysis. Rapid liquid phase lithography prototyping creates the multifunctional device economically

    Quadrupole transitions and quantum gates protected by continuous dynamic decoupling

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    Dynamical decoupling techniques are a versatile tool for engineering quantum states with tailored properties. In trapped ions, nested layers of continuous dynamical decoupling by means of radio-frequency field dressing can cancel dominant magnetic and electric shifts and therefore provide highly prolonged coherence times of electronic states. Exploiting this enhancement for frequency metrology, quantum simulation or quantum computation, poses the challenge to combine the decoupling with laser-ion interactions for the quantum control of electronic and motional states of trapped ions. Ultimately, this will require running quantum gates on qubits from dressed decoupled states. We provide here a compact representation of nested continuous dynamical decoupling in trapped ions, and apply it to electronic SS and DD states and optical quadrupole transitions. Our treatment provides all effective transition frequencies and Rabi rates, as well as the effective selection rules of these transitions. On this basis, we discuss the possibility of combining continuous dynamical decoupling and M{\o}lmer-S{\o}rensen gates

    Training report: Diagnostic procedures for PPR

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