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排序方式: 共有1433条查询结果,搜索用时 15 毫秒
81.
Arianna Piersanti Tamara Tavoloni Eleonora Bastari Carmela Lestingi Sara Romanelli Rosanna Rossi Giorgio Saluti Simone Moretti Roberta Galarini 《Food Analytical Methods》2018,11(2):355-366
This paper describes the development and validation of an analytical method to determine 15 polybrominated diphenyl ethers (PBDEs) in fish and shellfish tissues with gas chromatography coupled to triple quadrupole mass spectrometry using electron impact source (GC-EI-MS/MS). A QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe)-like procedure was applied; the extract was cleaned up on an acidic Extrelut-NT3 column connected on top of a silica cartridge and further purified with gel permeation chromatography (GPC). The SIM acquisition proved to yield better results than traditional MRM approach for octa-, nona-, and deca-brominated congeners. The validation study was carried out in inter-laboratory conditions. The average recoveries were in the range 66–118%, with relative standard deviations generally lower than or equal to 22%. Quality assurance and quality control practices were thoroughly described and highlighted. These long and tedious practices are fundamental to obtain reliable quantitative data during food monitoring programs and, therefore, to support daily intake assessments. Finally, the procedure was applied to the analysis of marine fish samples collected in local markets. Mackerel and mullet were the most contaminated species. 相似文献
82.
Marco Carminati Giorgio Ferrari Aleksandar P. Ivanov Tim Albrecht Marco Sampietro 《Analog Integrated Circuits and Signal Processing》2013,77(3):333-343
Solid-state nanopores have been gaining popularity in nano-biotechnology for single molecule detection, in particular for label-free high-throughput DNA sequencing. In order to address the improvement of the resolution/speed trade-off critical in this application, here we present a new two-channel current amplifier tailored for solid-state nanopore devices with integrated tunneling electrodes. The simultaneous detection of ion and tunneling currents provides enhanced molecule tracking capability. We describe the system design starting from a detailed noise analysis and device modeling, highlighting the detrimental role of the conductive silicon substrate and of all the stray capacitive couplings between the electrodes. Given the high input capacitance (0.1–1 nF), the input voltage noise has been carefully minimized choosing a discrete couple of matched low-noise JFETs as input stage, thus achieving an equivalent input noise of 1.5 nV/√Hz (corresponding to a current noise floor of 15 fA/√Hz at 10 kHz). Low-noise performance (11 pA rms noise integrated over a 75 kHz bandwidth) is preserved at a wide bandwidth (300 kHz) and high gain (100 MΩ) thanks to the adoption of an improved integrator/differentiator cascade topology. Furthermore, along with biasing networks and selectable low-pass filters, an AC-coupled channel providing additional gain has been introduced in order to “zoom” in the current signature during pore blockade events. Together with an experimental characterization of the system (and comparison with the noise performance of other instruments), the platform is validated by demonstrating the detection of λ-DNA with 20 nm pores. 相似文献
83.
84.
On measuring the accuracy of SLAM algorithms 总被引:1,自引:0,他引:1
Rainer Kümmerle Bastian Steder Christian Dornhege Michael Ruhnke Giorgio Grisetti Cyrill Stachniss Alexander Kleiner 《Autonomous Robots》2009,27(4):387-407
In this paper, we address the problem of creating an objective benchmark for evaluating SLAM approaches. We propose a framework
for analyzing the results of a SLAM approach based on a metric for measuring the error of the corrected trajectory. This metric
uses only relative relations between poses and does not rely on a global reference frame. This overcomes serious shortcomings
of approaches using a global reference frame to compute the error. Our method furthermore allows us to compare SLAM approaches
that use different estimation techniques or different sensor modalities since all computations are made based on the corrected
trajectory of the robot.
We provide sets of relative relations needed to compute our metric for an extensive set of datasets frequently used in the
robotics community. The relations have been obtained by manually matching laser-range observations to avoid the errors caused
by matching algorithms. Our benchmark framework allows the user to easily analyze and objectively compare different SLAM approaches. 相似文献
85.
Giorgio Abbiati Fabio Marinelli Elisabetta Rossi Antonio Arcadi 《Israel journal of chemistry》2013,53(11-12):856-868
The peculiar features of gold(III) and gold(I) species include exceptional carbophilicity and, at the same time, lone pair affinity. Such a combination offers many advantages for the development of more sustainable approaches to the synthesis of indole derivatives from readily available 2-alkynylanilines. This mini-review critically summarizes the literature reports in this field, with the aim to encourage further research activities in this promising area. 相似文献
86.
Delli Priscoli Francesco Di Giorgio Alessandro Lisi Federico Monaco Salvatore Pietrabissa Antonio Celsi Lorenzo Ricciardi Suraci Vincenzo 《International Journal of Control, Automation and Systems》2017,15(2):892-904
International Journal of Control, Automation and Systems - In the framework of the Future Internet, the aim of the Quality of Experience (QoE) Control functionalities is to track the personalized... 相似文献
87.
Marano S Palmieri F Franceschetti G 《Journal of the Optical Society of America. A, Optics, image science, and vision》2002,19(7):1319-1333
A fully self-contained discrete framework with discrete equivalents of Stokes's, Gauss's, and Green's theorems is presented. The formulation is analogous to that of continuous operators, but totally discrete in nature, and the exact relationships derived are shown to hold provided that a set of predefined rules is followed in building discrete contours and domains. The method allows for an analytical rigor that is not guaranteed if one translates the classical continuous formulations onto a discretized approximated framework. We clarify several issues related to the use of discrete operators, which may play a crucial role in specific applications such as the two-dimensional phase-unwrapping problem, chosen as our main application example, and we show that reconstruction on irregular domains and/or in the presence of undersampling and noise is better formulated in the discrete framework than in the continuous domain. 相似文献
88.
Petritoli A Ravegnani F Giovanelli G Bortoli D Bonafè U Kostadinov I Oulanovsky A 《Applied optics》2002,41(27):5593-5599
An airborne UV-visible spectrometer, the Gas Analyzer Spectrometer Correlating Optical Differences, airborne version (GASCOD/A4pi) was successfully operated during the Airborne Polar Experiment, Geophysica Aircraft in Antarctica airborne campaign from Ushuaia (54 degrees 49' S, 68 degrees 18' W), Argentina in southern spring 1999. The instrument measured scattered solar radiation through three optical windows with a narrow field of view (FOV), one from the zenith, two from the horizontal, as well as actinic fluxes through 2pi FOV radiometric heads. Only a few airborne measurements of scattered solar radiation at different angles from the zenith are available in the literature. With our configuration we attempted to obtain the average line-of-sight concentrations of detectable trace gases. The retrieval method, based on differential optical absorption spectroscopy, is described and results for ozone are shown and compared with measurements from an in situ instrument as the first method of validation. 相似文献
89.
In this paper, we present an evolutionary model of industry dynamics yielding endogenous business cycles with ‘Keynesian’
features. The model describes an economy composed of firms and consumers/workers. Firms belong to two industries. The first
one performs R&D and produces heterogeneous machine tools. Firms in the second industry invest in new machines and produce
a homogenous consumption good. Consumers sell their labor and fully consume their income. In line with the empirical literature
on investment patterns, we assume that the investment decisions by firms are lumpy and constrained by their financial structures.
Moreover, drawing from behavioral theories of the firm, we assume boundedly rational expectation formation. Simulation results
show that the model is able to deliver self-sustaining patterns of growth characterized by the presence of endogenous business
cycles. The model can also replicate the most important stylized facts concerning micro- and macro-economic dynamics. Indeed,
we find that investment is more volatile than GDP; consumption is less volatile than GDP; investment, consumption and change
in stocks are procyclical and coincident variables; employment is procyclical; unemployment rate is anticyclical; firm size
distributions are skewed but depart from log-normality; firm growth distributions are tent-shaped.
JEL Classifications: C15, C22, C49, E17, E22, E32. 相似文献
90.
Luigi Palopoli Domenico Rosaci Giorgio Terracina Domenico Ursino 《Knowledge and Information Systems》2005,8(4):462-497
The problem of handling both the integration and the cooperation of a large number of information sources characterised by
heterogeneous representation formats is a challenging issue. In this context, a central role can be played by the knowledge
about the semantic relationships holding between concepts belonging to different information sources (intersource properties).
In this paper, we propose a semiautomatic approach for extracting two kinds of intersource properties, namely synonymies and
homonymies, from heterogeneous information sources. In order to carry out the extraction task, we introduce both a conceptual
model, for representing involved sources, and a metrics, for measuring the strength of the semantic relationships holding
among concepts represented within the same source. 相似文献