On the order of a non-abelian representation group of a slim dense near hexagon

We show that, if the representation group $R$ of a slim dense near hexagon $S$ is non-abelian, then $R$ is of exponent 4 and $|R|=2^{\beta}$, $1+NPdim(S)\leq \beta\leq 1+dimV(S)$, where $NPdim(S)$ is the near polygon embedding dimension of $S$ and $dimV(S)$ is the dimension of the universal representation module $V(S)$ of $S$. Further, if $\beta =1+NPdim(S)$, then $R$ is an extraspecial 2-group (Theorem 1.6)

On hyperovals of polar spaces

We derive lower and upper bounds for the size of a hyperoval of a finite polar space of rank 3. We give a computer-free proof for the uniqueness, up to isomorphism, of the hyperoval of size 126 of H(5, 4) and prove that the near hexagon E-3 has up to isomorphism a unique full embedding into the dual polar space DH(5, 4)

Introduction: Planetary memory in contemporary American fiction

This special issue considers the ways in which contemporary American fiction seeks to imagine a mode of ‘planetary memory’ able to address the scalar and systemic complexities of the Anthropocene – the epoch in which the combined activity of the human species has become a geological force in its own right. As Naomi Klein has recently argued, confronting the problem of anthropogenic climate change alters everything we know about the world: demanding wholesale recalibration of economic and political priorities; destabilising the epistemic frameworks through which quotidian life is interpreted and enacted; and decentring the dominant cultural imaginaries that seek to give form to historical experienc

Geometric Hyperplanes of the Near Hexagon L_3 times GQ(2, 2)

Having in mind their potential quantum physical applications, we classify all geometric hyperplanes of the near hexagon that is a direct product of a line of size three and the generalized quadrangle of order two. There are eight different kinds of them, totalling to 1023 = 2^{10} - 1 = |PG(9, 2)|, and they form two distinct families intricately related with the points and lines of the Veldkamp space of the quadrangle in question.Comment: 10 pages, 5 figures and 2 tables; Version 2 - more detailed discussion of the properties of hyperplane

CII* Absorption in Damped Lyman Alpha Systems: (II) A New Window on the Star Formation History of the Universe

Starting from the SFR per unit physical area, determined for DLAs using the C II* method, we obtain the SFR per unit comoving volume at $z$ $\approx$ 3, and find that it agrees with that for the Lyman Break Galaxies (LBGs). Though the mass of produced stars indicated by the SFRs is consistent with the current densities of known stellar populations, the mass of metals produced by $z$=2.5 is 30 times larger than detected in absorption in DLAs. The most likely solutions to this ``missing metals'' problem is that star formation occurs in compact bulge regions. We search for evidence of feedback and find no correlations between the SFR per unit area and N(H I), but possible correlations between SFR per unit area and low-ion velocity width and SFR per unit area and metal abundance. We show that (a) the correlation between cooling rate and dust-to-gas ratio is positive evidence for grain photoelectric heating, (b) the CMB does not significantly populate the C II excited fine-structure states, and (c) the ratio of CII* to resonance-line optical depths is a sensitive probe of the multi-phase structure of the DLA gas. We address recent arguments that DLAs are comprised only of WNM gas, and show them to be inconclusive. Despite the rough agreement between SFR per unit comoving volume for DLAs and LBGs, current evidence indicates these are distinct populations

Response of thin-film SQUIDs to applied fields and vortex fields: Linear SQUIDs

In this paper we analyze the properties of a dc SQUID when the London penetration depth \lambda is larger than the superconducting film thickness d. We present equations that govern the static behavior for arbitrary values of \Lambda = \lambda^2/d relative to the linear dimensions of the SQUID. The SQUID's critical current I_c depends upon the effective flux \Phi, the magnetic flux through a contour surrounding the central hole plus a term proportional to the line integral of the current density around this contour. While it is well known that the SQUID inductance depends upon \Lambda, we show here that the focusing of magnetic flux from applied fields and vortex-generated fields into the central hole of the SQUID also depends upon \Lambda. We apply this formalism to the simplest case of a linear SQUID of width 2w, consisting of a coplanar pair of long superconducting strips of separation 2a, connected by two small Josephson junctions to a superconducting current-input lead at one end and by a superconducting lead at the other end. The central region of this SQUID shares many properties with a superconducting coplanar stripline. We calculate magnetic-field and current-density profiles, the inductance (including both geometric and kinetic inductances), magnetic moments, and the effective area as a function of \Lambda/w and a/w.Comment: 18 pages, 20 figures, revised for Phys. Rev. B, the main revisions being to denote the effective flux by \Phi rather than

Quantum Monte Carlo Algorithm Based on Two-Body Density Functional Theory for Fermionic Many-Body Systems: Application to 3He

We construct a quantum Monte Carlo algorithm for interacting fermions using the two-body density as the fundamental quantity. The central idea is mapping the interacting fermionic system onto an auxiliary system of interacting bosons. The correction term is approximated using correlated wave functions for the interacting system, resulting in an effective potential that represents the nodal surface. We calculate the properties of 3He and find good agreement with experiment and with other theoretical work. In particular, our results for the total energy agree well with other calculations where the same approximations were implemented but the standard quantum Monte Carlo algorithm was usedComment: 4 pages, 3 figures, 1 tabl