4,455 research outputs found
General solution for Hamiltonians with extended cubic and quartic potentials
We integrate with hyperelliptic functions a two-particle Hamiltonian with
quartic potential and additionnal linear and nonpolynomial terms in the
Liouville integrable cases 1:6:1 and 1:6:8.Comment: LaTex 2e. To appear, Theoretical and Mathematical Physics 200
PALSAR wide-area mapping and annual monitoring methodology for Borneo
This paper describes the operational radar mapping processing chain developed and steps taken to produce a provisional wide-area PALSAR forest and land cover map of Borneo for the year 2007, compliant with emerging international standards (CEOS guidelines, FAO LCCS). The methodology is based on the classification of FBS and FBD image pairs. To cover Borneo the equivalent of 554 standard images is required. The final overall accuracy assessment result shows this demonstration map product is in 85.5% full agreement with the independent reference dataset and in 7.8% âpartial agreementâ. Monitoring land cover change on an annual basis requires consistent year-to-year mapping. This implies that the localised and temporal effects of environmental factors on the backscatter level (such as inundation or El Niño drought) and variation due to differing observation dates/cycles (related to change of season) have to be accounted for strip by strip. New concepts for (a) automated intercalibration of radar data, (b) time-consistency and (c) automated adaptation of radar signatures to changing environmental conditions have been evaluated for its usefulness to improve the classification and the consistency of annual monitoring
Completeness of the cubic and quartic H\'enon-Heiles Hamiltonians
The quartic H\'enon-Heiles Hamiltonian passes the Painlev\'e test for
only four sets of values of the constants. Only one of these, identical to the
traveling wave reduction of the Manakov system, has been explicitly integrated
(Wojciechowski, 1985), while the three others are not yet integrated in the
generic case . We integrate them by building
a birational transformation to two fourth order first degree equations in the
classification (Cosgrove, 2000) of such polynomial equations which possess the
Painlev\'e property. This transformation involves the stationary reduction of
various partial differential equations (PDEs). The result is the same as for
the three cubic H\'enon-Heiles Hamiltonians, namely, in all four quartic cases,
a general solution which is meromorphic and hyperelliptic with genus two. As a
consequence, no additional autonomous term can be added to either the cubic or
the quartic Hamiltonians without destroying the Painlev\'e integrability
(completeness property).Comment: 10 pages, To appear, Theor.Math.Phys. Gallipoli, 34 June--3 July 200
Integration of a generalized H\'enon-Heiles Hamiltonian
The generalized H\'enon-Heiles Hamiltonian
with an additional
nonpolynomial term is known to be Liouville integrable for three
sets of values of . It has been previously integrated by genus
two theta functions only in one of these cases. Defining the separating
variables of the Hamilton-Jacobi equations, we succeed here, in the two other
cases, to integrate the equations of motion with hyperelliptic functions.Comment: LaTex 2e. To appear, Journal of Mathematical Physic
Hydrodynamics and sediment transport. Fundamental aspects related to sustainable management of sandy coasts: aim and scope of the research project
The main scientific objectives of this research proposal can be summarised in the question why certain sandy coasts are dynamically stable and others are not. The following tools will be used to search for the answer:âąLiterature studyâąBuilding of a framework to model sediment transport in the near shore zoneâąIncorporation of the influence of complex spectra in the formulation of sediment transport influenced by currents and wavesâą Synergy of understanding of the physical processes (theoretical basis), numerical and physical modellingâą Qualitative confrontation with available in situ measurementsSince we are convinced that the planned research activities are of international value, not only in terms of scientific merits but also from the point of view of sustainable coastal development, the following objectives form also part of this proposal:âąCollaboration with other research teams in Europe who deal with this topic, for example by participating in experiments in the framework of TMR-LSFâąWriting and submitting of a problem oriented and interdisciplinary research proposal to the E.U.âąDissimination of the results through conferences and by publication in international journal
Loss mechanisms of surface plasmon polaritons on gold probed by cathodoluminescence imaging spectroscopy
We use cathodoluminescence imaging spectroscopy to excite surface plasmon polaritons and measure their decay length on single crystal and polycrystalline gold surfaces. The surface plasmon polaritons are excited on the gold surface by a nanoscale focused electron beam and are coupled into free space radiation by gratings fabricated into the surface. By scanning the electron beam on a line perpendicular to the gratings, the propagation length is determined. Data for single-crystal gold are in agreement with calculations based on dielectric constants. For polycrystalline films, grain boundary scattering is identified as additional loss mechanism, with a scattering coefficient SG=0.2%
Trust in public relations in the age of mistrusted media: A European perspective
One of the core problems of misinformation and post-trust societies is, indeed, trust in communications. The undermining of the credibility of media as the backbone of democratic societies is becoming a serious problem that affects democracy, business and all kinds of public institutions and organizations in society(ies). This paper explores perceptions of trust in key stakeholders involved in communication on behalf of organizations. Findings are considered at the professional (macro), departmental (meso) and individual (micro) level as well as considering the trusted role of non-specialist communicators for organizations including internal and external spokespeople. Data were collected from an online survey of 2883 respondents from 46 countries across Europe. Key findings were at the macro level that: antagonism between management communication professionals and journalists remains. The lowest trust in the profession is felt to be by the general public. At the meso level, top executives are perceived to trust the department the most followed by journalists in second place. External experts such as professors and consultants are perceived to be the most trusted by the general public. Finally, at the micro level individuals are more trusted than organizations or departments and the communication profession more widely
High quality ultrafast transmission electron microscopy using resonant microwave cavities
Ultrashort, low-emittance electron pulses can be created at a high repetition
rate by using a TM deflection cavity to sweep a continuous beam across
an aperture. These pulses can be used for time-resolved electron microscopy
with atomic spatial and temporal resolution at relatively large average
currents. In order to demonstrate this, a cavity has been inserted in a
transmission electron microscope, and picosecond pulses have been created. No
significant increase of either emittance or energy spread has been measured for
these pulses.
At a peak current of pA, the root-mean-square transverse normalized
emittance of the electron pulses is m rad in the direction parallel to the streak of the cavity, and
m rad in the perpendicular
direction for pulses with a pulse length of 1.1-1.3 ps. Under the same
conditions, the emittance of the continuous beam is
m rad.
Furthermore, for both the pulsed and the continuous beam a full width at half
maximum energy spread of eV has been measured
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