Method for the preparation of thin-skinned asymmetric reverse osmosis membranes and products thereof

A method for preparing water insoluble asymmetric membranes from water soluble polymers is discussed. The process involves casting a film of the polymer, partially drying it, and then contacting it with a concentrated solution of a transition metal salt. The transition metal ions render the polymer insoluable and are believed to form a complex with it. Optionally, the polymer is crosslinked with heat or radiation. The most preferred polymer is poly(vinyl alcohol). The most preferred complexing salt is copper sulfate. The process and the metal ion linked membranes are discussed. The membranes are reverse osmosis membranes

A Conformal Truncation Framework for Infinite-Volume Dynamics

We present a new framework for studying conformal field theories deformed by one or more relevant operators. The original CFT is described in infinite volume using a basis of states with definite momentum, $P$, and conformal Casimir, $\mathcal{C}$. The relevant deformation is then considered using lightcone quantization, with the resulting Hamiltonian expressed in terms of this CFT basis. Truncating to states with $\mathcal{C} \leq \mathcal{C}_{\max}$, one can numerically find the resulting spectrum, as well as other dynamical quantities, such as spectral densities of operators. This method requires the introduction of an appropriate regulator, which can be chosen to preserve the conformal structure of the basis. We check this framework in three dimensions for various perturbative deformations of a free scalar CFT, and for the case of a free $O(N)$ CFT deformed by a mass term and a non-perturbative quartic interaction at large-$N$. In all cases, the truncation scheme correctly reproduces known analytic results. We also discuss a general procedure for generating a basis of Casimir eigenstates for a free CFT in any number of dimensions.Comment: 48+37 pages, 17 figures; v2: references added, small clarification

Nonperturbative Matching Between Equal-Time and Lightcone Quantization

We investigate the nonperturbative relation between lightcone (LC) and standard equal-time (ET) quantization in the context of $\lambda \phi^4$ theory in $d=2$. We discuss the perturbative matching between bare parameters and the failure of its naive nonperturbative extension. We argue that they are nevertheless the same theory nonperturbatively, and that furthermore the nonperturbative map between bare parameters can be extracted from ET perturbation theory via Borel resummation of the mass gap. We test this map by using it to compare physical quantities computed using numerical Hamiltonian truncation methods in ET and LC.Comment: 22+8 pages, 10 figure

Boydbolt, a positive-latch, simple-release fastener

Fastener /Boydbolt/ has recently been designed to furnish positive lock and release characteristics that positively prevent accidental adverse functions of lock or release

Inter-Industry Wage Differences and Theories of Wage Determination

Numerous studies have shown large differences in wages for apparently similar workers across industries. These findings pose a challenge to standard model s of labor market behavior. A problem with past studies of industry wage differences is that they have failed to distinguish between union and nonunion workers. Many economists may expect union workers wages to be set in a noncompetitive fashion but would be surprised if nonunion wages were. We examine the differences in wages across industries for both union and nonunion workers. We find that even after controlling for a wide range of personal characteristics and geographic location large wage differences persist for both union and nonunion workers. Furthermore the premiums of union and nonunion workers are highly correlated. We review past studies which demonstrate that industry wage premiums are also highly correlated across countries and have been very similar over many decades. We present new evidence that the wages of different occupations are highly correlated across industries -- that is if any occupation in an industry is highly paid all occupations are. We also review the evidence which suggests that people who move from low to high paying industries receive a large fraction of the industry wage premium and that those who move from high to low paying industries lose the premium. Finally, we review the evidence on the correlates of industry wage differences. Quit rates, human capital variables, capital labor ratios and market power measures are all positively correlated with industry wage differences individually though the data are not adequate to determine their independent contributions in multiple regression. On the basis of all the evidence we conclude that standard labor market clearing models can not easily explain all the facts. Several alternative models are discussed including efficiency wage and collective action threat mode1 s. These are found to be more consistent with the facts though some troubling problems remain.

The status of pentaquark spectroscopy on the lattice

The present work is a summary of the status of lattice pentaquark calculations. After a pedagogic introduction to the basics of lattice hadron spectroscopy we give a critical comparison of results presently available in the literature. Special emphasis is put on presenting some of the possible pitfalls of these calculations. In particular we discuss at length the choice of the hadronic operators and the separation of genuine five-quark states from meson-baryon scattering states.Comment: 13 pages LaTeX, 1 eps figur

Pentaquark hadrons from lattice QCD

We study spin 1/2 isoscalar and isovector candidates in both parity channels for the recently discovered \Theta^+(1540) pentaquark particle in quenched lattice QCD. Our analysis takes into account all possible uncertainties, such as statistical, finite size and quenching errors when performing the chiral and continuum extrapolations and we have indications that our signal is separated from scattering states. The lowest mass that we find in the I^P=0^- channel is in complete agreement with the experimental value of the \Theta^+ mass. On the other hand, the lowest mass state in the opposite parity I^P=0^+ channel is much higher. Our findings suggests that the parity of the \Theta^+ is negative.Comment: 13 pages, 5 figures. Final version, appeared in JHE

Perfect Scalars on the Lattice

We perform renormalization group transformations to construct optimally local perfect lattice actions for free scalar fields of any mass. Their couplings decay exponentially. The spectrum is identical to the continuum spectrum, while thermodynamic quantities have tiny lattice artifacts. To make such actions applicable in simulations, we truncate the couplings to a unit hypercube and observe that spectrum and thermodynamics are still drastically improved compared to the standard lattice action. We show how preconditioning techniques can be applied successfully to this type of action. We also consider a number of variants of the perfect lattice action, such as the use of an anisotropic or triangular lattice, and modifications of the renormalization group transformations motivated by wavelets. Along the way we illuminate the consistent treatment of gauge fields, and we find a new fermionic fixed point action with attractive properties.Comment: 26 pages, 11 figure