Modular Groups of Quantum Fields in Thermal States

For a quantum field in a thermal equilibrium state we discuss the group generated by time translations and the modular action associated with an algebra invariant under half-sided translations. The modular flows associated with the algebras of the forward light cone and a space-like wedge admit a simple geometric description in two dimensional models that factorize in light-cone coordinates. At large distances from the domain boundary compared to the inverse temperature the flow pattern is essentially the same as time translations, whereas the zero temperature results are approximately reproduced close to the edge of the wedge and the apex of the cone. Associated with each domain there is also a one parameter group with a positive generator, for which the thermal state is a ground state. Formally, this may be regarded as a certain converse of the Unruh-effect.Comment: 28 pages, 4 figure

Endomorphism Semigroups and Lightlike Translations

Certain criteria are demonstrated for a spatial derivation of a von Neumann algebra to generate a one-parameter semigroup of endomorphisms of that algebra. These are then used to establish a converse to recent results of Borchers and of Wiesbrock on certain one-parameter semigroups of endomorphisms of von Neumann algebras (specifically, Type III_1 factors) that appear as lightlike translations in the theory of algebras of local observables.Comment: 9 pages, Late

Charged sectors, spin and statistics in quantum field theory on curved spacetimes

The first part of this paper extends the Doplicher-Haag-Roberts theory of superselection sectors to quantum field theory on arbitrary globally hyperbolic spacetimes. The statistics of a superselection sector may be defined as in flat spacetime and each charge has a conjugate charge when the spacetime possesses non-compact Cauchy surfaces. In this case, the field net and the gauge group can be constructed as in Minkowski spacetime. The second part of this paper derives spin-statistics theorems on spacetimes with appropriate symmetries. Two situations are considered: First, if the spacetime has a bifurcate Killing horizon, as is the case in the presence of black holes, then restricting the observables to the Killing horizon together with "modular covariance" for the Killing flow yields a conformally covariant quantum field theory on the circle and a conformal spin-statistics theorem for charged sectors localizable on the Killing horizon. Secondly, if the spacetime has a rotation and PT symmetry like the Schwarzschild-Kruskal black holes, "geometric modular action" of the rotational symmetry leads to a spin-statistics theorem for charged covariant sectors where the spin is defined via the SU(2)-covering of the spatial rotation group SO(3).Comment: latex2e, 73 page

Trypsin Inhibitor. VII. Comparative Nutritive Value of Raw and Heated Soybean Meal for Poults

I. The trypsin inhibitor contained in one-half of a lot of soybean meal was destroyed by autoclaving at 15 pounds for 20 minutes. 2. This portion of the meal when fed at a level of 24 per cent to newly hatched poults gave a significantly greater gain in five weeks than did an equal amount of meal in which the inhibitor had not been destroyed. 3. The difference in growth is attributed to the destruction of the trypsin inhibitor

The Utilization of Food Elements by Growing Chicks. XIII. The Effect of Additions of Dehydrated Alfalfa Meal to High Corn Chick Rations

Feeding trials were conducted on three groups of chicks in eight lots receiving a growing mash containing dehydrated alfalfa meal at levels of 2, 3, 4, 5, 6, 9, 10, 12, and 15 per cent. Comparisons were not made simultaneously but no general trend toward growth depression was evident in comparable lots. In addition duplicate trials of four lots of newly hatched New Hampshire chicks were made on pelleted rations carrying 0, 2, 4, and 6 per cent of a good quality dehydrated alfalfa meal. The chicks were all fed accurately known amounts of the pelleted rations for six weeks. In each of the duplicate trials the lot fed 2 per cent alfalfa meal made slightly better gains than the other lots. The lots fed 4 and 6 per cent alfalfa made as good gains as the control lots fed no alfalfa. It is evident that with the sample of dehydrated alfalfa meal used in these experiments no adverse effect was produced by the alfalfa. Another trial of four lots was made on rations containing 0, 5, 10 and 15 per cent of alfalfa meal. In this case equal gains were made by each of the alfalfa-fed lots and all were better than the control without alfalfa. It is also seen that the efficiency of gain was higher in the alfalfa-fed lots than in the control. Perhaps most interesting of all is the difference in time required to finish equal amounts of feed. Here the advantage is definitely in favor of the alfalfa-fed lots

The Utilization of Food Elements by Growing Chicks. XIII. The Effect of Additions of Dehydrated Alfalfa Meal to High Corn Chick Rations

Feeding trials were conducted on three groups of chicks in eight lots receiving a growing mash containing dehydrated alfalfa meal at levels of 2, 3, 4, 5, 6, 9, 10, 12, and 15 per cent. Comparisons were not made simultaneously but no general trend toward growth depression was evident in comparable lots. In addition duplicate trials of four lots of newly hatched New Hampshire chicks were made on pelleted rations carrying 0, 2, 4, and 6 per cent of a good quality dehydrated alfalfa meal. The chicks were all fed accurately known amounts of the pelleted rations for six weeks. In each of the duplicate trials the lot fed 2 per cent alfalfa meal made slightly better gains than the other lots. The lots fed 4 and 6 per cent alfalfa made as good gains as the control lots fed no alfalfa. It is evident that with the sample of dehydrated alfalfa meal used in these experiments no adverse effect was produced by the alfalfa. Another trial of four lots was made on rations containing 0, 5, 10 and 15 per cent of alfalfa meal. In this case equal gains were made by each of the alfalfa-fed lots and all were better than the control without alfalfa. It is also seen that the efficiency of gain was higher in the alfalfa-fed lots than in the control. Perhaps most interesting of all is the difference in time required to finish equal amounts of feed. Here the advantage is definitely in favor of the alfalfa-fed lots

An Algebraic Jost-Schroer Theorem for Massive Theories

We consider a purely massive local relativistic quantum theory specified by a family of von Neumann algebras indexed by the space-time regions. We assume that, affiliated with the algebras associated to wedge regions, there are operators which create only single particle states from the vacuum (so-called polarization-free generators) and are well-behaved under the space-time translations. Strengthening a result of Borchers, Buchholz and Schroer, we show that then the theory is unitarily equivalent to that of a free field for the corresponding particle type. We admit particles with any spin and localization of the charge in space-like cones, thereby covering the case of string-localized covariant quantum fields.Comment: 21 pages. The second (and crucial) hypothesis of the theorem has been relaxed and clarified, thanks to the stimulus of an anonymous referee. (The polarization-free generators associated with wedge regions, which always exist, are assumed to be temperate.

A New Approach to Spin and Statistics

We give an algebraic proof of the spin-statistics connection for the parabosonic and parafermionic quantum topological charges of a theory of local observables with a modular PCT-symmetry. The argument avoids the use of the spinor calculus and also works in 1+2 dimensions. It is expected to be a progress towards a general spin-statistics theorem including also (1+2)-dimensional theories with braid group statistics.Comment: LATEX, 15 pages, no figure

Flight Research at Ames: Fifty-Seven Years of Development and Validation of Aeronautical Technology

This NASA special publication presents a general overview of the flight research that has been conducted at Ames Research Center over the last 57 years. Icing research, transonic model testing, aerodynamics, variable stability aircraft, boundary layer control, short takeoff and landing (STOL), vertical/ short takeoff and landing (V/STOL) and rotorcraft research are among the major topics of interest discussed. Flying qualities, stability and control, performance evaluations, gunsight tracking and guidance and control displays research are also presented. An epilogue is included which presents the significant contributions that came about as a result of research and development conducted at Ames