Zobrazeno 1 - 10
of 954
pro vyhledávání: '"van der Geer, P"'
Autor:
van der Geer, Gerard, Yu, Xun
We give a bound on the number of weighted real forms of a complex variety with finite automorphism group, where the weight is the inverse of the number of automorphisms of the real form. We give another bound involving the Sylow 2-subgroup and as an
Externí odkaz:
http://arxiv.org/abs/2401.13284
We prove a formula for the cycle class of the supersingular locus in the Chow ring with rational coefficients of the moduli space of principally polarized abelian varieties in characteristic $p$. This formula determines this class as a monomial in th
Externí odkaz:
http://arxiv.org/abs/2307.14393
We construct vector-valued modular forms on moduli spaces of curves and abelian varieties using effective divisors in projectivized Hodge bundles over moduli of curves. Cycle relations tell us the weight of these modular forms. In particular we const
Externí odkaz:
http://arxiv.org/abs/2302.00329
Field emitted electrons can seriously affect the operation of high-field, high-duty factor electron accelerators. Accelerated field emission can result in high average power beams which can radiation damage beamline components. In addition, localized
Externí odkaz:
http://arxiv.org/abs/2212.07993
Autor:
Cléry, Fabien, van der Geer, Gerard
We discuss two simple but useful observations that allow the construction of modular forms from given ones using invariant theory. The first one deals with elliptic modular forms and their derivatives, and generalizes the Rankin-Cohen bracket, while
Externí odkaz:
http://arxiv.org/abs/2211.05611
Autor:
Jessica Carilli, Jason Baer, Jenna Marie Aquino, Mark Little, Bart Chadwick, Forest Rohwer, Gunther Rosen, Anneke van der Geer, Andrés Sánchez-Quinto, Ashton Ballard, Aaron C. Hartmann
Publikováno v:
PeerJ, Vol 12, p e17640 (2024)
Anthropogenic stressors like overfishing, land based runoff, and increasing temperatures cause the degradation of coral reefs, leading to the loss of corals and other calcifiers, increases in competitive fleshy algae, and increases in microbial patho
Externí odkaz:
https://doaj.org/article/923f0bfb66204105add6d8202961bdaa
Autor:
J. T. Yoskowitz, G. A. Krafft, G. Palacios-Serrano, S. A. K. Wijethunga, J. Grames, J. Hansknecht, C. Hernandez-Garcia, M. Poelker, M. L. Stutzman, R. Suleiman, C. A. Valerio-Lizarraga, S. B. Van Der Geer
Publikováno v:
Physical Review Accelerators and Beams, Vol 27, Iss 12, p 123401 (2024)
GaAs photocathodes in dc high-voltage photoguns are highly susceptible to ion back-bombardment, which reduces the photocathode quantum efficiency and limits the useful operating lifetime for producing polarized electron beams. This paper demonstrates
Externí odkaz:
https://doaj.org/article/db9db36c61c542ee8717a7be0b4c8086
Autor:
van der Geer, Gerard
This is a survey paper dealing with moduli aspects of curves over finite fields. It discusses counting points of moduli spaces, relations with modular forms and stratifications on moduli spaces.
Comment: 29 pages. To appear in: Curves over finit
Comment: 29 pages. To appear in: Curves over finit
Externí odkaz:
http://arxiv.org/abs/2112.08704
Autor:
Cléry, Fabien, van der Geer, Gerard
We use the description of the Picard modular surface for discriminant $-3$ as a moduli space of curves of genus $3$ to generate all vector-valued Picard modular forms from bi-covariants for the action of ${GL}_2$ on the space of pairs of binary forms
Externí odkaz:
http://arxiv.org/abs/2110.00849
Autor:
George A. Lyras, Lars Werdelin, Bartholomeus G. M. van der Geer, Alexandra A. E. van der Geer
Publikováno v:
Communications Biology, Vol 6, Iss 1, Pp 1-8 (2023)
Abstract Pinnipeds (seals and related species) use their whiskers to explore their environment and locate their prey. Today they live mostly in marine habitats and are adapted for a highly specialised amphibious lifestyle with their flippers for loco
Externí odkaz:
https://doaj.org/article/919bb9a7a9dd4bfcb45c98ddfc4e281e