Induction probe determines levels of liquid metals

Mutual-inductance probe accurately measures liquid levels in a variety of liquid metals at elevated temperatures. It can be used in pyrochemical processes for the recovery of spent reactor fuel

Determination of tungsten resonance absorption integrals by activation

Determination of tungsten resonance absorption integrals by activatio

Globalization and Traceability of Agricultural Production: The Role of Mechanization

Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is an Invited Paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 4 (2002): F. Pierce and R. Cavalieri. Globalization and Traceability of Agricultural Production: The Role of Mechanization. Club of Bologna. Vol. IV. September 2002

Titanium-nitrogen reaction investigated for application to gettering systems

Titanium is one of several gettering materials available for removing nitrogen from inert gases. The reaction rate of titanium-metal sponge and nitrogen in argon-nitrogen mixtures was studied at 900 degrees C. The rate was found to depend upon the partial pressure of nitrogen in the gas phase. Mathematical relationships simulate titanium systems

Introduction to Categories and Categorical Logic

The aim of these notes is to provide a succinct, accessible introduction to some of the basic ideas of category theory and categorical logic. The notes are based on a lecture course given at Oxford over the past few years. They contain numerous exercises, and hopefully will prove useful for self-study by those seeking a first introduction to the subject, with fairly minimal prerequisites. The coverage is by no means comprehensive, but should provide a good basis for further study; a guide to further reading is included. The main prerequisite is a basic familiarity with the elements of discrete mathematics: sets, relations and functions. An Appendix contains a summary of what we will need, and it may be useful to review this first. In addition, some prior exposure to abstract algebra - vector spaces and linear maps, or groups and group homomorphisms - would be helpful.Comment: 96 page

Crossover from ballistic to Epstein diffusion in the free-molecular regime

We investigate, through simulation, a system of aggregating particles in the free molecular regime that undergoes a crossover from ballistic to diffusive motion. As the aggregates grow, the aggregate mean free path becomes smaller and the motion between collisions becomes more diffusive. From growth kinetics we find that when the ratio of the aggregate mean path to the mean aggregate nearest neighbor separation reaches of the order of unity, a crossover to diffusive motion occurs. This ratio, called the nearest neighbor Knudsen number, becomes an important parameter in understanding aerosol aggregation in the free molecular regime

Quantum Films Adsorbed on Graphite: Third and Fourth Helium Layers

Using a path-integral Monte Carlo method for simulating superfluid quantum films, we investigate helium layers adsorbed on a substrate consisting of graphite plus two solid helium layers. Our results for the promotion densities and the dependence of the superfluid density on coverage are in agreement with experiment. We can also explain certain features of the measured heat capacity as a function of temperature and coverage.Comment: 13 pages in the Phys. Rev. two-column format, 16 Figure

Are animal models of addiction useful?

Background: Preclinical research involving non-human animals has made important contributions to our understanding of risk-factors for addiction, neuroadaptations that follow chronic drug exposure, and to the development of some efficacious pharmacotherapies for addiction. Despite these contributions, we argue that animal models of addiction have impeded progress in our understanding of addiction and its treatment in humans. Argument: First of all, the majority of pharmacological treatments that were initially developed using animal models have failed to prove effective for the treatment of addiction in humans, resulting in a huge waste of resources. Secondly, we demonstrate that prevailing animal models that portray addiction as a disorder of compulsion and habit cannot be reconciled with observations that psychoactive drug use in humans is a goal-directed operant behaviour that remains under the control of its consequences, even in people who are addicted. Thirdly, addiction may be a uniquely human phenomenon that is dependent on language, which necessarily limits the validity of animal models. Finally, we argue that addicted brains must be understood as one component of broader networks of symptoms and environmental and social factors that are impossible to model in laboratory animals. Conclusions: A case can be made that animal models of addiction have not served us well in understanding and treating addiction in humans. It is important to reconsider some widely-held beliefs about the nature of addictive behaviour in humans that have arisen from the zeal to translate observations of laboratory animals

Radiative corrections to the Higgs boson decay rate Γ(H→ZZ)\Gamma(H\rightarrow ZZ) in the minimal supersymmetric model

We consider radiative corrections to the decay rate $\Gamma(H\rightarrow ZZ)$ of the heavy {\it CP}-even Higgs boson of the minimal supersymmetric model to two $Z$ bosons. We perform a one loop Feynman diagram calculation in the on-mass-shell renormalization scheme, and include the third generation of quarks and squarks. The tree level rate is suppressed by a mixing angle factor and decreases as $1/M_H$ for large $M_H$. The corrected rate overcomes this suppression and increases with $M_H$ for $M_H > 500$~GeV. The corrections can be very large and depend in detail on the top squark masses and $A$-term, as well as the supersymmetric Higgs mass parameter $\mu$.Comment: 22 pages, 9 figures available from authors, UCB-PTH-92/23 and LBL-3249

Anomalous prompt photon production in hadronic collisions at low-xTx_T

We investigate the discrepancy that exists at low-$x_T=2p_T/\sqrt{s}$ between the next--to--leading order QCD calculations of prompt photon production and the measured cross section. The central values of the measured cross section are of order 100\% larger than QCD predictions in this region. It has been suggested that the bremsstrahlung contribution may account for this discrepancy. The quark fragmentation function $D_{\gamma/q}(z)$ has not been measured and an exactly known asymptotic form is normally used in calculations. We examine the effect of much larger fragmentation functions on the QCD predictions. After illustrating the effect of the large fragmentation functions in some detail for recent CDF data at $\sqrt{s}$=1.8~TeV, we perform a $\chi^2$ fit to 8 prompt photon data sets ranging in CMS energy from 24~GeV to 1.8~TeV. While a large fragmentation function normalization may prove to play an important role in resolving the discrepancy, the present theoretical and experimental uncertainties prevent any definite normalization value from being determined.Comment: 14 pages, LBL-33122 and UCB-PTH-92/38. 13 figures available by email, specify postscript or topdrawe