scholarly journals The gap phenomenon in parabolic geometries

Author(s):  
Boris Kruglikov ◽  
Dennis The

AbstractThe infinitesimal symmetry algebra of any Cartan geometry has maximum dimension realized by the flat model, but often this dimension drops significantly when considering non-flat geometries, so a gap phenomenon arises. For general (regular, normal) parabolic geometries of type

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Clifford Cheung ◽  
Zander Moss

Abstract We argue that symmetry and unification can emerge as byproducts of certain physical constraints on dynamical scattering. To accomplish this we parameterize a general Lorentz invariant, four-dimensional theory of massless and massive scalar fields coupled via arbitrary local interactions. Assuming perturbative unitarity and an Adler zero condition, we prove that any finite spectrum of massless and massive modes will necessarily unify at high energies into multiplets of a linearized symmetry. Certain generators of the symmetry algebra can be derived explicitly in terms of the spectrum and three-particle interactions. Furthermore, our assumptions imply that the coset space is symmetric.


2018 ◽  
Vol 24 (2) ◽  
pp. 175-183
Author(s):  
Jean-Claude Ndogmo

Abstract Variational and divergence symmetries are studied in this paper for the whole class of linear and nonlinear equations of maximal symmetry, and the associated first integrals are given in explicit form. All the main results obtained are formulated as theorems or conjectures for equations of a general order. A discussion of the existence of variational symmetries with respect to a different Lagrangian, which turns out to be the most common and most readily available one, is also carried out. This leads to significantly different results when compared with the former case of the transformed Lagrangian. The latter analysis also gives rise to more general results concerning the variational symmetry algebra of any linear or nonlinear equations.


2020 ◽  
Vol 101 (8) ◽  
pp. E1241-E1258 ◽  
Author(s):  
Matthew R. Kumjian ◽  
Rachel Gutierrez ◽  
Joshua S. Soderholm ◽  
Stephen W. Nesbitt ◽  
Paula Maldonado ◽  
...  

Abstract On 8 February 2018, a supercell storm produced gargantuan (>15 cm or >6 in. in maximum dimension) hail as it moved over the heavily populated city of Villa Carlos Paz in Córdoba Province, Argentina. Observations of gargantuan hail are quite rare, but the large population density here yielded numerous witnesses and social media pictures and videos from this event that document multiple large hailstones. The storm was also sampled by the newly installed operational polarimetric C-band radar in Córdoba. During the RELAMPAGO campaign, the authors interviewed local residents about their accounts of the storm and uncovered additional social media video and photographs revealing extremely large hail at multiple locations in town. This article documents the case, including the meteorological conditions supporting the storm (with the aid of a high-resolution WRF simulation), the storm’s observed radar signatures, and three noteworthy hailstones observed by residents. These hailstones include a freezer-preserved 4.48-in. (11.38 cm) maximum dimension stone that was scanned with a 3D infrared laser scanner, a 7.1-in. (18 cm) maximum dimension stone, and a hailstone photogrammetrically estimated to be between 7.4 and 9.3 in. (18.8–23.7 cm) in maximum dimension, which is close to or exceeds the world record for maximum dimension. Such a well-observed case is an important step forward in understanding environments and storms that produce gargantuan hail, and ultimately how to anticipate and detect such extreme events.


2014 ◽  
Vol 592-594 ◽  
pp. 2728-2732 ◽  
Author(s):  
V.P. Chandramohan ◽  
Prabal Talukdar

Deformation of potato is estimated by experimentally during convective drying. Size of the potato slice is 4cm x 2cm x 2cm. The percentage changes in length, breadth and width of potato are estimated during drying. Shrinkage of the object during drying is estimated. Air velocity chosen for this present analysis is 2 m/s and the range of air temperature is selected as 40 to 70 °C. The product experiences the maximum dimension changes upto 30% in length and 47.5 % in both breadth and width wise. The parameters are non dimensionalised to get generic solution.


2021 ◽  
Vol 78 ◽  
pp. 101793
Author(s):  
Antonio J. Di Scala ◽  
Carlos E. Olmos ◽  
Francisco Vittone
Keyword(s):  

1997 ◽  
Vol 11 (01) ◽  
pp. 17-24
Author(s):  
M. A. Rego-Monteiro

We show that an interesting open asymmetric XXZ quantum spin chain with surface fields is invariant under a two-parametric generalization of the slq(2) algebra with deformation parameters being a particular root of unit.


2018 ◽  
Vol 128 (6) ◽  
pp. 1792-1798 ◽  
Author(s):  
Gurpreet S. Gandhoke ◽  
Yash K. Pandya ◽  
Ashutosh P. Jadhav ◽  
Tudor Jovin ◽  
Robert M. Friedlander ◽  
...  

OBJECTIVEThe price of coils used for intracranial aneurysm embolization has continued to rise despite an increase in competition in the marketplace. Coils on the US market range in list price from $500 to $3000. The purpose of this study was to investigate potential cost savings with the use of a price capitation model.METHODSThe authors built a clinical decision analytical tree and compared their institution’s current expenditure on endovascular coils to the costs if a capped-price model were implemented. They retrospectively reviewed coil and cost data for 148 patients who underwent coil embolization from January 2015 through September 2016. Data on the length and number of coils used in all patients were collected and analyzed. The probabilities of a treated aneurysm being ≤/> 10 mm in maximum dimension, the total number of coils used for a case being ≤/> 5, and the total length of coils used for a case being ≤/> 50 cm were calculated, as was the mean cost of the currently used coils for all possible combinations of events with these probabilities. Using the same probabilities, the authors calculated the expected value of the capped-price strategy in comparison with the current one. They also conducted multiple 1-way sensitivity analyses by applying plausible ranges to the probabilities and cost variables. The robustness of the results was confirmed by applying individual distributions to all studied variables and conducting probabilistic sensitivity analysis.RESULTSNinety-five (64%) of 148 patients presented with a rupture, and 53 (36%) were treated on an elective basis. The mean aneurysm size was 6.7 mm. A total of 1061 coils were used from a total of 4 different providers. Companies A (72%) and B (16%) accounted for the major share of coil consumption. The mean number of coils per case was 7.3. The mean cost per case (for all coils) was $10,434. The median total length of coils used, for all coils, was 42 cm. The calculated probability of treating an aneurysm less than 10 mm in maximum dimension was 0.83, for using 5 coils or fewer per case it was 0.42, and for coil length of 50 cm or less it was 0.89. The expected cost per case with the capped policy was calculated to be $4000, a cost savings of $6564 in comparison with using the price of Company A. Multiple 1-way sensitivity analyses revealed that the capped policy was cost saving if its cost was less than $10,500. In probabilistic sensitivity analyses, the lowest cost difference between current and capped policies was $2750.CONCLUSIONSIn comparison with the cost of coils from the authors’ current provider, their decision model and probabilistic sensitivity analysis predicted a minimum $407,000 to a maximum $1,799,976 cost savings in 148 cases by adapting the capped-price policy for coils.


Sign in / Sign up

Export Citation Format

Share Document