1,737 research outputs found
More on coupling coefficients for the most degenerate representations of SO(n)
We present explicit closed-form expressions for the general group-theoretical
factor appearing in the alpha-topology of a high-temperature expansion of
SO(n)-symmetric lattice models. This object, which is closely related to
6j-symbols for the most degenerate representation of SO(n), is discussed in
detail.Comment: 9 pages including 1 table, uses IOP macros Update of Introduction and
Discussion, References adde
Unravelling work drive: A comparison between workaholism and overcommitment
Workaholism and overcommitment are often used as interchangeable constructs describing an individual’s over-involvement toward their own job. Employees with high levels in both constructs are characterized by an excessive effort and attachment to their job, with the incapability to detach from it and negative consequences in terms of poor health and job burnout. However, few studies have simultaneously measured both constructs, and their relationships are still not clear. In this study, we try to disentangle workaholism and overcommitment by comparing them with theoretically related contextual and personal antecedents, as well as their health consequences. We conducted a nonprobability mixed mode research design on 133 employees from different organizations in Italy using both self-and other-reported measures. To test our hypothesis that workaholism and overcommitment are related yet different constructs, we used partial correlations and regression analyses. The results confirm that these two constructs are related to each other, but also outline that overcommitment (and not workaholism) is uniquely related to job burnout, so that overcommitment rather than workaholism could represent the true negative aspect of work drive. Additionally, workaholism is more related to conscientiousness than overcommitment, while overcommitment shows a stronger relationship with neuroticism than workaholism. The theoretical implications are discussed
Intertwining relations of non-stationary Schr\"odinger operators
General first- and higher-order intertwining relations between non-stationary
one-dimensional Schr\"odinger operators are introduced. For the first-order
case it is shown that the intertwining relations imply some hidden symmetry
which in turn results in a -separation of variables. The Fokker-Planck and
diffusion equation are briefly considered. Second-order intertwining operators
are also discussed within a general approach. However, due to its complicated
structure only particular solutions are given in some detail.Comment: 18 pages, LaTeX20
Influence of tunneling on electron screening in low energy nuclear reactions in laboratories
Using a semiclassical mean field theory, we show that the screening potential
exhibits a characteristic radial variation in the tunneling region in sharp
contrast to the assumption of the constant shift in all previous works. Also,
we show that the explicit treatment of the tunneling region gives a larger
screening energy than that in the conventional approach, which studies the time
evolution only in the classical region and estimates the screening energy from
the screening potential at the external classical turning point. This
modification becomes important if the electronic state is not a single
adiabatic state at the external turning point either by pre-tunneling
transitions of the electronic state or by the symmetry of the system even if
there is no essential change with the electronic state in the tunneling region.Comment: 3 figure
Accuracy of Trace Formulas
Using quantum maps we study the accuracy of semiclassical trace formulas. The
role of chaos in improving the semiclassical accuracy, in some systems, is
demonstrated quantitatively. However, our study of the standard map cautions
that this may not be most general. While studying a sawtooth map we demonstrate
the rather remarkable fact that at the level of the time one trace even in the
presence of fixed points on singularities the trace formula may be exact, and
in any case has no logarithmic divergences observed for the quantum bakers map.
As a byproduct we introduce fantastic periodic curves akin to curlicues.Comment: 20 pages, uuencoded and gzipped, 1 LaTex text file and 9 PS files for
figure
Ultra-large polymer-free suspended graphene films
Due to its extraordinary properties, suspended graphene is a critical element
in a wide range of applications. Preparation methods that preserve the unique
properties of graphene are therefore in high demand. To date, all protocols for
the production of large graphene films have relied on the application of a
polymer film to stabilize graphene during the transfer process. However, this
inevitably introduces contaminations that have proven to be extremely
difficult, if not impossible, to remove entirely. Here we report the
polymer-free fabrication of suspended films consisting of three graphene layers
spanning circular holes of 150 m diameter. We find a high fabrication
yield, very uniform properties of the freestanding graphene across all holes as
well across individual holes. A detailed analysis by confocal Raman and THz
spectroscopy reveals that the triple-layer samples exhibit structural and
electronic properties similar to those of monolayer graphene. We demonstrate
their usability as ion-electron converters in time-of-flight mass spectrometry
and related applications. They are two orders of magnitude thinner than
previous carbon foils typically used in these types of experiments, while still
being robust and exhibiting a sufficiently high electron yield. These results
are an important step towards replacing free-standing ultra-thin carbon films
or graphene from polymer-based transfers with much better defined and clean
graphene.Comment: 9 pagers, 5 figure
Calculations of time-dependent observables in non-Hermitian quantum mechanics: The problem and a possible solution
The solutions of the time independent Schrodinger equation for non-Hermitian
(NH) Hamiltonians have been extensively studied and calculated in many
different fields of physics by using L^2 methods that originally have been
developed for the calculations of bound states. The existing non-Hermitian
formalism breaks down when dealing with wavepackets(WP). An open question is
how time dependent expectation values can be calculated when the Hamiltonian is
NH ? Using the F-product formalism, which was recently proposed, [J. Phys.
Chem., 107, 7181 (2003)] we calculate the time dependent expectation values of
different observable quantities for a simple well known study test case model
Hamiltonian. We carry out a comparison between these results with those
obtained from conventional(i.e., Hermitian) quantum mechanics (QM)
calculations. The remarkable agreement between these results emphasizes the
fact that in the NH-QM, unlike standard QM, there is no need to split the
entire space into two regions; i.e., the interaction region and its
surrounding. Our results open a door for a type of WP propagation calculations
within the NH-QM formalism that until now were impossible.Comment: 20 pages, 5 Postscript figures. To be Published in Physical Review
Deformed defects for scalar fields with polynomial interactions
In this paper we use the deformation procedure introduced in former work on
deformed defects to investigate several new models for real scalar field. We
introduce an interesting deformation function, from which we obtain two
distinct families of models, labeled by the parameters that identify the
deformation function. We investigate these models, which identify a broad class
of polynomial interactions. We find exact solutions describing global defects,
and we study the corresponding stability very carefully.Comment: 8 pages, 5 eps figures, to appear in PR
New Two-Dimensional Integrable Quantum Models from SUSY Intertwining
Supersymmetrical intertwining relations of second order in the derivatives
are investigated for the case of supercharges with deformed hyperbolic metric
. Several classes of particular solutions of these
relations are found. The corresponding Hamiltonians do not allow the
conventional separation of variables, but they commute with symmetry operators
of fourth order in momenta. For some of these models the specific SUSY
procedure of separation of variables is applied.Comment: 18 page
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