59 research outputs found
Singular behaviour of the electromagnetic field
The singularities of the electromagnetic field are derived to include all the
point-like multipoles representing an electric charge and current distribution.
Firstly derived in the static case, the result is generalized to the dynamic
one. We establish a simple procedure for passing from the first, to the second
case.Comment: Latex, 21.pages, no figure
Measurement of the charm and beauty structure functions using the H1 vertex detector at HERA
Inclusive charm and beauty cross sections are measured in e − p and e + p neutral current collisions at HERA in the kinematic region of photon virtuality 5≤Q 2≤2000 GeV2 and Bjorken scaling variable 0.0002≤x≤0.05. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189 pb−1. The numbers of charm and beauty events are determined using variables reconstructed by the H1 vertex detector including the impact parameter of tracks to the primary vertex and the position of the secondary vertex. The measurements are combined with previous data and compared to QCD predictions
Tropospheric delay parameters from numerical weather models for multi-GNSS precise positioning
The recent dramatic development of multi-GNSS (Global Navigation Satellite
System) constellations brings great opportunities and potential for more
enhanced precise positioning, navigation, timing, and other applications.
Significant improvement on positioning accuracy, reliability, as well as
convergence time with the multi-GNSS fusion can be observed in comparison
with the single-system processing like GPS (Global Positioning System). In
this study, we develop a numerical weather model (NWM)-constrained precise
point positioning (PPP) processing system to improve the multi-GNSS precise
positioning. Tropospheric delay parameters which are derived from the
European Centre for Medium-Range Weather Forecasts (ECMWF) analysis are
applied to the multi-GNSS PPP, a combination of four systems: GPS, GLONASS,
Galileo, and BeiDou. Observations from stations of the IGS (International
GNSS Service) Multi-GNSS Experiments (MGEX) network are processed, with both
the standard multi-GNSS PPP and the developed NWM-constrained multi-GNSS PPP
processing. The high quality and accuracy of the tropospheric delay
parameters derived from ECMWF are demonstrated through comparison and
validation with the IGS final tropospheric delay products. Compared to the
standard PPP solution, the convergence time is shortened by 20.0, 32.0, and
25.0 % for the north, east, and vertical components, respectively, with
the NWM-constrained PPP solution. The positioning accuracy also benefits from
the NWM-constrained PPP solution, which was improved by 2.5, 12.1, and
18.7 % for the north, east, and vertical components, respectively
Virtue ethics and social psychology
Virtue ethics has emerged as an alternative to deontological and utilitarian theory in recent moral philosophy. The basic notion of virtue ethics is to reassert the importance of virtuous character in ethical judgement in contrast to the emphasis on principles and consequences. Since questions of virtue have been largely neglected in modern moral theory, there has been a return to Aristotle’s account of virtue as character. This in turn has been questioned as the basis of virtue ethics and there has been a search for alternative accounts of moral agency. One aspect of this critical reflection on virtue ethics is an engagement with social psychology as a source of criticism of the Aristotelian conception of character and as a more plausible alternative foundation for a theory of moral character with contemporary relevance. This paper aims to introduce this area of moral theory to a psychological audience and reflect on the interpretation of social psychological theory and evidence in criticisms of virtuous character, focusing on the use of Milgram’s (1974) experiments on obedience to authority as an argument for situationism. A number of questions emerge concerning the interpretation and use of social psychological theory and evidence in debates within moral philosophy
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