Free energies and critical exponents of the A_1^{(1)}, B_n^{(1)}, C_n^{(1)} and D_n^{(1)} face models

We obtain the free energies and critical exponents of models associated with elliptic solutions of the star-triangle relation and reflection equation. The models considered are related to the affine Lie algebras A_1^{(1)}, B_n^{(1)},C_n^{(1)} and D_n^{(1)}. The bulk and surface specific heat exponents are seen to satisfy the scaling relation 2\alpha_s = \alpha_b + 2. It follows from scaling relations that in regime III the correlation length exponent \nu is given by \nu=(l+g)/2g, where l is the level and g is the dual Coxeter number. In regime II we find \nu=(l+g)/2l.Comment: 9 pages, Latex, no figure

Ground State of the Quantum Symmetric Finite Size XXZ Spin Chain with Anisotropy Parameter Δ=1/2\Delta = {1/2}

We find an analytic solution of the Bethe Ansatz equations (BAE) for the special case of a finite XXZ spin chain with free boundary conditions and with a complex surface field which provides for $U_q(sl(2))$ symmetry of the Hamiltonian. More precisely, we find one nontrivial solution, corresponding to the ground state of the system with anisotropy parameter $\Delta = {1/2}$ corresponding to $q^3 = -1$.Comment: 6 page

Enzymic degradation of luteinizing hormone-releasing hormone (LH-RH) by hypothalamic tissue.

Synthetic luteinizing hormone-releasing hormone (LH-RH) lost both its immunore-activity and hormonal activity on incubation with hypothalamic or cerebrocortical slices or homogenates. This inactivation was shown to be due to degradation of the decapeptide by soluble enzyme(s) present in the 100,000 × g supernatant fraction of the homogenates. The supernatant derived from one rat hypothalamus was capable of destroying 1 μg of exogenous LH-RH within 5 min. The hexapeptide pGlu-His-Trp-Ser-Tyr-Gly was identified as the major radioactive breakdown product of [pGlu-3-3H] LH-RH, and tentative evidence for the formation of the tetrapeptide Leu-Arg-Pro-Gly-NH2 was obtained by sequential electrophoresis and paper chromatography. These findings suggest that the Gly-Leu bond may be the preferred site of cleavage. © 1974

The transmission of nosocomial pathogens in an intensive care unit: a space–time clustering and structural equation modelling approach

We investigated the incidence of cases of nosocomial pathogens and risk factors in an intensive treatment unit ward to determine if the number of cases is dependent on location of patients and the colonization/infection history of the ward. A clustering approach method was developed to investigate the patterns of spread of cases through time for five microorganisms [methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter spp., Klebsiella spp., Candida spp., and Pseudomonas aeruginosa] using hospital microbiological monitoring data and ward records of patient-bed use. Cases of colonization/infection by MRSA, Candida and Pseudomonas were clustered in beds and through time while cases of Klebsiella and Acinetobacter were not. We used structural equation modelling to analyse interacting risk factors and the potential pathways of transmission in the ward. Prior nurse contact with colonized/infected patients, mediated by the number of patient-bed movements, were important predictors for all cases, except for those of Pseudomonas. General health and invasive surgery were significant predictors of cases of Candida and Klebsiella. We suggest that isolation and bed movement as a strategy to manage MRSA infections is likely to impact upon the incidence of cases of other opportunist pathogen

Switching kinetics of ferroelectric polymer nanomesas

The switching dynamics and switching time of ferroelectric nanomesas grown from the paraelectric phase of ultrathin Langmuir–Blodgett vinylidene fluoride and trifluoroethylene copolymer films are investigated. Ferroelectric nanomesas are created through heat treatment and self-organization and have an average height of 10 nm and an average diameter of 100 nm. Ferroelectric nanomesas are highly crystalline and are in the ferroelectric phase and switch faster than 50 μs. The dependence of switching time on applied voltage implies an extrinsic switching nature

Auxiliary matrices on both sides of the equator

The spectra of previously constructed auxiliary matrices for the six-vertex model at roots of unity are investigated for spin-chains of even and odd length. The two cases show remarkable differences. In particular, it is shown that for even roots of unity and an odd number of sites the eigenvalues contain two linear independent solutions to Baxter's TQ-equation corresponding to the Bethe ansatz equations above and below the equator. In contrast, one finds for even spin-chains only one linear independent solution and complete strings. The other main result is the proof of a previous conjecture on the degeneracies of the six-vertex model at roots of unity. The proof rests on the derivation of a functional equation for the auxiliary matrices which is closely related to a functional equation for the eight-vertex model conjectured by Fabricius and McCoy.Comment: 22 pages; 2nd version: one paragraph added in the conclusion and some typos correcte

The Importance of being Odd

In this letter I consider mainly a finite XXZ spin chain with periodic boundary conditions and \bf{odd} \rm number of sites. This system is described by the Hamiltonian $H_{xxz}=-\sum_{j=1}^{N}\{\sigma_j^{x}\sigma_{j+1}^{x} +\sigma_j^{y}\sigma_{j+1}^{y} +\Delta \sigma_j^z\sigma_{j+1}^z\}$. As it turned out, its ground state energy is exactly proportional to the number of sites $E=-3N/2$ for a special value of the asymmetry parameter $\Delta=-1/2$. The trigonometric polynomial $q(u)$, zeroes of which being the parameters of the ground state Bethe eigenvector is explicitly constructed. This polynomial of degree $n=(N-1)/2$ satisfy the Baxter T-Q equation. Using the second independent solution of this equation corresponding to the same eigenvalue of the transfer matrix, it is possible to find a derivative of the ground state energy w.r.t. the asymmetry parameter. This derivative is closely connected with the correlation function $=-1/2+3/2N^2$. In its turn this correlation function is related to an average number of spin strings for the ground state of the system under consideration: $= {3/8}(N-1/N)$. I would like to stress once more that all these simple formulas are \bf wrong \rm in the case of even number of sites. Exactly this case is usually considered.Comment: 9 pages, based on the talk given at NATO Advanced Research Workshop "Dynamical Symmetries in Integrable Two-dimensional Quantum Field Theories and Lattice Models", 25-30 September 2000, Kyiv, Ukraine. New references are added plus some minor correction