1,665 research outputs found
Coherent state triplets and their inner products
It is shown that if H is a Hilbert space for a representation of a group G,
then there are triplets of spaces F_H, H, F^H, in which F^H is a space of
coherent state or vector coherent state wave functions and F_H is its dual
relative to a conveniently defined measure. It is shown also that there is a
sequence of maps F_H -> H -> F^H which facilitates the construction of the
corresponding inner products. After completion if necessary, the F_H, H, and
F^H, become isomorphic Hilbert spaces. It is shown that the inner product for H
is often easier to evaluate in F_H than F^H. Thus, we obtain integral
expressions for the inner products of coherent state and vector coherent state
representations. These expressions are equivalent to the algebraic expressions
of K-matrix theory, but they are frequently more efficient to apply. The
construction is illustrated by many examples.Comment: 33 pages, RevTex (Latex2.09) This paper is withdrawn because it
contained errors that are being correcte
Effective Free Energy for Individual Dynamics
Physics and economics are two disciplines that share the common challenge of
linking microscopic and macroscopic behaviors. However, while physics is based
on collective dynamics, economics is based on individual choices. This
conceptual difference is one of the main obstacles one has to overcome in order
to characterize analytically economic models. In this paper, we build both on
statistical mechanics and the game theory notion of Potential Function to
introduce a rigorous generalization of the physicist's free energy, which
includes individual dynamics. Our approach paves the way to analytical
treatments of a wide range of socio-economic models and might bring new
insights into them. As first examples, we derive solutions for a congestion
model and a residential segregation model.Comment: 8 pages, 2 figures, presented at the ECCS'10 conferenc
Nonlinear collective nuclear motion
For each real number a Lie algebra of nonlinear vector fields on
three dimensional Euclidean space is reported. Although each algebra is
mathematically isomorphic to , only the vector
fields correspond to the usual generators of the general linear group. The
vector fields integrate to a nonstandard action of the general
linear group; the case integrates to a local Lie semigroup. For
each , a family of surfaces is identified that is invariant with
respect to the group or semigroup action. For positive the surfaces
describe fissioning nuclei with a neck, while negative surfaces
correspond to exotic bubble nuclei. Collective models for neck and bubble
nuclei are given by irreducible unitary representations of a fifteen
dimensional semidirect sum spectrum generating algebra spanned by its
nonlinear subalgebra plus an abelian nonlinear inertia tensor
subalgebra.Comment: 13 pages plus two figures(available by fax from authors by request
Algebraic nonlinear collective motion
Finite-dimensional Lie algebras of vector fields determine geometrical
collective models in quantum and classical physics. Every set of vector fields
on Euclidean space that generates the Lie algebra sl(3, R) and contains the
angular momentum algebra so(3) is determined. The subset of divergence-free
sl(3, R) vector fields is proven to be indexed by a real number . The
solution is the linear representation that corresponds to the
Riemann ellipsoidal model. The nonlinear group action on Euclidean space
transforms a certain family of deformed droplets among themselves. For positive
, the droplets have a neck that becomes more pronounced as
increases; for negative , the droplets contain a spherical bubble of
radius . The nonlinear vector field algebra is extended to
the nonlinear general collective motion algebra gcm(3) which includes the
inertia tensor. The quantum algebraic models of nonlinear nuclear collective
motion are given by irreducible unitary representations of the nonlinear gcm(3)
Lie algebra. These representations model fissioning isotopes () and
bubble and two-fluid nuclei ().Comment: 32pages, 4 figures not include
Performance of a live multi-gateway LoRaWAN and interference measurement across indoor and outdoor localities
Little work has been reported on the magnitude and impact of interference with the performance of Internet of Things (IoT) applications operated by Long-Range Wide-Area Network (LoRaWAN) in the unlicensed 868 MHz Industrial, Scientific, and Medical (ISM) band. The propagation performance and signal activity measurement of such technologies can give many insights to effectively build long-range wireless communications in a Non-Line of Sight (NLOS) environment. In this paper, the performance of a live multi-gateway in indoor office site in Glasgow city was analysed in 26 days of traffic measurement. The indoor network performances were compared to similar performance measurements from outdoor LoRaWAN test traffic generated across Glasgow Central Business District (CBD) and elsewhere on the same LoRaWAN. The results revealed 99.95% packet transfer success on the first attempt in the indoor site compared to 95.7% at the external site. The analysis shows that interference is attributed to nearly 50 X greater LoRaWAN outdoor packet loss than indoor. The interference measurement results showed a 13.2–97.3% and 4.8–54% probability of interfering signals, respectively, in the mandatory Long-Range (LoRa) uplink and downlink channels, capable of limiting LoRa coverage in some areas
Cloning and sequence analysis of cDNAs encoding the cytosolic precursors of subunits GapA and GapB of chloroplast glyceraldehyde-3-phosphate dehydrogenase from pea and spinach
Chloroplast glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is composed of two different subunits, GapA and GapB. cDNA clones containing the entire coding sequences of the cytosolic precursors for GapA from pea and for GapB from pea and spinach have been identified, sequenced and the derived amino acid sequences have been compared to the corresponding sequences from tobacco, maize and mustard. These comparisons show that GapB differs from GapA in about 20% of its amino acid residues and by the presence of a flexible and negatively charged C-terminal extension, possibly responsible for the observed association of the enzyme with chloroplast envelopes in vitro. This C-terminal extension (29 or 30 residues) may be susceptible to proteolytic cleavage thereby leading to a conversion of chloroplast GAPDH isoenzyme I into isoenzyme II. Evolutionary rate comparisons at the amino acid sequence level show that chloroplast GapA and GapB evolve roughly two-fold slower than their cytosolic counterpart GapC. GapA and GapB transit peptides evolve about 10 times faster than the corresponding mature subunits. They are relatively long (68 and 83 residues for pea GapA and spinach GapB respectively) and share a similar amino acid framework with other chloroplast transit peptides
Irreducible decomposition for tensor prodect representations of Jordanian quantum algebras
Tensor products of irreducible representations of the Jordanian quantum
algebras U_h(sl(2)) and U_h(su(1,1)) are considered. For both the highest
weight finite dimensional representations of U_h(sl(2)) and lowest weight
infinite dimensional ones of U_h(su(1,1)), it is shown that tensor product
representations are reducible and that the decomposition rules to irreducible
representations are exactly the same as those of corresponding Lie algebras.Comment: LaTeX, 14pages, no figur
Prevalence and predictors of long-acting reversible contraceptive use among sexually active women in 26 sub-Saharan African countries.
BackgroundLong-acting reversible contraceptives (LARCs) are associated with high efficacy rates and continuity of use. Based on the foregoing, we sought to examine the prevalence and factors associated with LARC use among sexually active women in 26 countries in sub-Saharan Africa(SSA).MethodsSecondary data from Demographic and Health Surveys conducted in 26 countries in SSA between January 2010 and December 2019 were pooled and analysed. A total of 56 067 sexually active women 15-49 y of age met the inclusion criteria. Bivariate and multivariate regression analyses were performed to examine the association between selected factors and the use of LARCs in SSA. Results were presented as crude odds ratios and adjusted odds ratios (aORs) with statistical precision at ResultsThe prevalence of LARC use was 21.73%, ranging from 1.94% in Namibia to 54.96% in Benin. Sexually active women with secondary or higher education (aOR 1.19 [95% confidence interval {CI} 1.08 to 1.32]), those cohabiting (aOR 1.25 [95% CI 1.06 to 1.47]) and those with four or more children (aOR 2.22 [95% CI 1.78 to 2.78]) were more likely to use LARCs compared with those without education, never married and with no biological child.ConclusionsThe use of LARCs in the 26 countries in SSA was relatively low. Hence, the identified contributory factors of LARC use should be tackled with appropriate interventions. These include continuous campaigns on the efficacy of LARCs in reducing unintended pregnancy, maternal mortality and morbidity
Computing a maximum clique in geometric superclasses of disk graphs
In the 90's Clark, Colbourn and Johnson wrote a seminal paper where they
proved that maximum clique can be solved in polynomial time in unit disk
graphs. Since then, the complexity of maximum clique in intersection graphs of
d-dimensional (unit) balls has been investigated. For ball graphs, the problem
is NP-hard, as shown by Bonamy et al. (FOCS '18). They also gave an efficient
polynomial time approximation scheme (EPTAS) for disk graphs. However, the
complexity of maximum clique in this setting remains unknown. In this paper, we
show the existence of a polynomial time algorithm for a geometric superclass of
unit disk graphs. Moreover, we give partial results toward obtaining an EPTAS
for intersection graphs of convex pseudo-disks
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A parametric study on in-situ hydrogen production from hydrocarbon reservoirs – Effect of reservoir and well properties
Supplementary data are available online at: https://www.sciencedirect.com/science/article/pii/S0360319924028544?via%3Dihub#appsec1 .Energy transition is a key driver to combat climate change and achieve zero carbon future. Sustainable and cost-effective hydrogen production will provide valuable addition to the renewable energy mix and help minimize greenhouse gas emissions. This study investigates the performance of in-situ hydrogen production (IHP) process, using a full-field compositional model as a precursor to experimental validation The reservoir model was simulated as one geological unit with a single point uniform porosity value of 0.13 and a five-point connection type between cell to minimize computational cost. Twenty-one hydrogen forming reactions were modelled based on the reservoir fluid composition selected for this study. The thermodynamic and kinetic parameters for the reactions were obtained from published experiments due to the absence of experimental data specific to the reservoir. A total of fifty-four simulation runs were conducted using CMG STARS software for 5478 days and cumulative hydrogen produced for each run was recorded. Results generated were then used to build a proxy model using Box-Behnken design of experiment method and Support Vector Machine with RBF kernel. To ascertain accuracy of the proxy models, analysis of variance (ANOVA) was conducted on the variables. The average absolute percentage error between the proxy model and numerical simulation was calculated to be 10.82%. Optimization of the proxy model was performed using genetic algorithm to maximize cumulative hydrogen produced. Based on this optimized model, the influence of porosity, permeability, well location, injection rate, and injection pressure were studied. Key results from this study reveals that lower permeability and porosity reservoirs supports more hydrogen yield, injection pressure had a negligible effect on hydrogen yield, and increase in oxygen injection rate corelated strongly with hydrogen production until a threshold value beyond which hydrogen yield decreased. The framework developed in the study could be used as tool to assess candidate reservoirs for in-situ hydrogen production.Funding for this project was received from Petroleum Technology Development Fund, under grant number
PTDF/ED/PHD/PPI/1028/1
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