The Rate of Weakening of Paper Due to an Applied Stress

Introduction When a load is applied to a sheet of paper, the paper may break immediately or it may support the load for some period of time. It is recognized that the paper, while under a stress less than that required to cause immediate break, is weakened until it is finally unable to support the stress. Since in the normal use of paper the stress to which paper is subjected is less than that needed to cause immediate break this weakening is an important factor in many cases. A few examples of such cases are the winding of the paper onto the reel of the paper machine during manufacture, the use of paper in bags, and possibly most important of all the running of paper through a printing press. Since approximately 90 per cent of all paper is printed by some means or another, and during the printing process the paper is subjected to stresses, the subject of weakening while under stress is very important. Should the paper be weakened to the breaking point in the printing operation, many costly shutdowns and wastes of materials could result

Lasing in Strong Coupling

An almost ideal thresholdless laser can be realized in the strong-coupling regime of light-matter interaction, with Poissonian fluctuations of the field at all pumping powers and all intensities of the field. This ideal scenario is thwarted by quantum nonlinearities when crossing from the linear to the stimulated emission regime, resulting in a universal jump in the second order coherence, which measurement could however be used to establish a standard of lasing in strong coupling.Comment: 5 pages, 2 figure

Twisting type-N vacuum fields with a group H2H_2

We derive the equations corresponding to twisting type-N vacuum gravitational fields with one Killing vector and one homothetic Killing vector by using the same approach as that developed by one of us in order to treat the case with two non-commuting Killing vectors. We study the case when the homothetic parameter $\phi$ takes the value -1, which is shown to admit a reduction to a third-order real ordinary differential equation for this problem, similar to that previously obtained by one of us when two Killing vectors are present.Comment: LaTeX, 11 pages. To be published in Classical and Quantum Gravit

Proper Motion of Pulsar B1800-21

We report high angular resolution, multi-epoch radio observations of the young pulsar PSR B1800-21. Using two pairs of data sets, each pair spanning approximately a ten year period, we calculate the proper motion of the pulsar. We obtain a proper motion of mu_alpha=11.6 +- 1.8 mas/yr, mu_delta=14.8 +- 2.3 mas/yr, which clearly indicates a birth position at the extreme edge of the W30 supernova remnant. Although this does not definitively rule out an association of W30 and PSR B1800-21, it does not support an association.Comment: 13 pages, 1 color figure. Replaced with version accepted for publication in Astrophysical Journa

New first integral for twisting type-N vacuum gravitational fields with two non-commuting Killing vectors

A new first integral for the equations corresponding to twisting type-N vacuum gravitational fields with two non-commuting Killing vectors is introduced. A new reduction of the problem to a complex second-order ordinary differential equation is given. Alternatively, the mentioned first integral can be used in order to provide a first integral of the second-order complex equation introduced in a previous treatment of the problem.Comment: 7 pages, LaTeX, uses ioplppt.sty and iopl12.sty; to be published in Class. Quantum Gra

Registration, labeling and inspection of commercial fertilizers, 1939

Cover title

The seeding of cowpeas

Caption title.Digitized 2006 AES MoU

Cropping systems in relation to erosion control

Cover title.Includes bibliographical references