30,123 research outputs found
The invariant rings of the Sylow groups of GU(3,q2), GU(4,q2), Sp(4,q) and O+(4,q) in the natural characteristic
No full textLet G be a Sylow p -subgroup of the unitary groups GU(3,q2)GU(3,q2), GU(4,q2)GU(4,q2), the symplectic group Sp(4,q)Sp(4,q) and, for q odd, the orthogonal group O+(4,q)O+(4,q). In this paper we construct a presentation for the invariant ring of G acting on the natural module. In particular we prove that these rings are generated by orbit products of variables and certain invariant polynomials which are images under Steenrod operations, applied to the respective invariant form defining the corresponding classical group. We also show that these generators form a SAGBI basis and the invariant ring for G is a complete intersection
Q&A with Hao Gu
No full textHao Gu spoke with Cell Reports about his scientific journey, inspirations to become a scientist, and his work on molecular mechanisms driving the progression of tumors of the digestive system; in particular, he discussed his lab’s recent work regarding the role of circDNA2v in colorectal cancer
q-Differential equations for q-classical polynomials and q-Jacobi-Stirling numbers
No full textWe introduce, characterise and provide a combinatorial interpretation for the so-called q-Jacobi–Stirling numbers.
This study is motivated by their key role in the (reciprocal) expansion of any power of a second order
q-differential operator having the q-classical polynomials as eigenfunctions in terms of other even order operators,
which we explicitly construct in this work. The results here obtained can be viewed as the q-version of
those given by Everitt et al. and by the first author, whilst the combinatorics of this new set of numbers is a
q-version of the Jacobi–Stirling numbers given by Gelineau and the second author
GU-Q organises roundtable on teaching Arabic
No full textThe Arabic Heritage Programme at Georgetown Qatar University (GU-Q) held a roundtable on teaching Arabic in the context of the Common European Framework of Reference for Languages (CEFRL) and comparing it to other references and frameworks, such as the standards of the American Council on Teaching of Foreign Languages (ACTFL)
Ultrafast shifted-core coaxial nano-emitter
No full textWe present an ultrafast nanoscale light source utilizing a shifted- core coaxial nanocavity, with a footprint of merely one-third of its emission wavelength in all three dimensions at telecommunication wavelengths. We show that, by shifting the metallic core off center of the coaxial structure, the effective mode volume of the cavity can be as small as 0.0078 x (λ₀/n_a)³, resulting in a Purcell factor over 390 and a modulation bandwidth exceeding 60GHz. We further show that the evolution trend of the cavity Q factor as a function of core- shifting distance can be engineered by choosing proper substrate material. Compared to its symmetric counterpart, this shifted-core coaxial nano-cavity features not only higher Q factor, Purcell factor, and modulation bandwidth but also an improved emission directivity that is essential in its coupling with other on-chip components. The proposed nano-emitter also features robust single mode operation over the entire core-shifting range, resulting in a near-unity spontaneous emission factor. Therefore, this device can be a good candidate for low power optical interconnect applications.Erik Jonsson School of Engineering and Computer Scienc
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Network Q
No full textA press release from Network Q announcing that they will begin featuring Brian McNaught, a gay columnist and author, for a monthly segment
Network Q
No full textA press release from Network Q announcing that they will begin featuring Brian McNaught, a gay columnist and author, for a monthly segment
Elastoplastic model for response and response sensitivity analysis of metallic dissipative devices and implementation in OpenSees
No full textAn elastoplastic model for metallic hysteretic dissipative devices allowing a straightforward physical interpretation of the constitutive parameters of the model, explicit computation of response quantities related to failure and dissipated energy, is implemented into OpenSees. The implemented algorithms include response and consistent response sensitivity results to the constitutive model parameters. Specifically, response sensitivity results are obtained through the direct differentiation method (DDM) and their derivation and implementation validated through the forward finite difference method (FDM). Selected results response sensitivity analysis and a simulated model updating problem are illustrated and discussed using as a case study a realistic multi-storey steel frame with BRBs subjected to a set of seismic accelerations
Elastoplastic model for buckling-restrained braces: response and response sensitivity analysis
No full textBuckling-restrained braces (BRBs) permit exploiting the hysteretic properties of their core material both in tension and compression. However, the global behaviour of BRBs does not fully replicate the local behaviour of their core material and requires the use of specific constitutive models. In this paper a recently developed elastoplastic constitutive model for BRBs is reviewed and its implementation in OpenSees discussed. Such model allows a straightforward physical interpretation and identification of the constitutive parameters as well as direct computation of response quantities related to failure and dissipated energy, with good predictions of the experimental behaviour. The algorithms implemented in OpenSees include response and consistent response sensitivity to the constitutive parameters of the BRB model. Selected results for response and response sensitivity analysis are illustrated and discussed using as testbed structure a realistic steel frame with BRBs
Model for response and response sensitivity analyses of BRBs in OpenSees
No full textBuckling-restrained braces (BRBs) permit exploiting the hysteretic properties of their core material both in tension and compression. However, the global behaviour of BRBs does not fully replicate the local behaviour of their core material and requires the use of specific constitutive models. In this paper a recently developed elastoplastic constitutive model for BRBs is reviewed and its implementation in OpenSees discussed. Such model allows a straightforward physical interpretation and identification of the constitutive parameters as well as direct computation of response quantities related to failure and dissipated energy, with accurate predictions of the experimental behaviour. The algorithms implemented in OpenSees include response and consistent response sensitivity to the constitutive parameters of the BRB model. Selected results for response and response sensitivity analysis are illustrated and discussed using as case study a realistic steel frame with BRBs
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