On the Quantum Theory of the Autoelectric Field Currents

By the application of a sufficiently intense electric field a Bohr atom could be rendered unstable. For when the drop in potential across the electronic orbit reaches a value of the order of magnitude of the ionizing potential of the atom (10^9 volts/cm.), the electron, instead of remaining in the neighborhood of the nucleus will fall down the hill of potential energy, and the atom will be dissociated. This dissociation is explosive in character. For there is a critical field strength, below which the atom remains stable indefinitely and above which it dissociates in a time of the order of the orbital periods of the atom. The characteristic for the autoelectric current should accordingly show abrupt discontinuities

Joshua Oppenheimer Early Works

A collection of hitherto unpublished short films in which methods of self-staging and reflexivity deployed in the author's feature-length films are developed. Total runtime 177 min, 23 min additional material

Acts of Killing

Oppenheimer presents Acts of Killing, a major 14-screen video installation at the Danish Film Institute. The project emerged from Joshua Oppenheimer’s research in the 1965-66 genocide, and performative documentary methods (2001-2005). Oppenheimer served as editor, cinematographer, camera operator, and was creatively responsible for all aspects of research, production, editing, and postproduction

The Look of Silence

The Look of Silence is Joshua Oppenheimer’s powerful companion piece to the Oscar®-nominated The Act of Killing. Through Oppenheimer’s footage of perpetrators of the 1965 Indonesian genocide, a family of survivors discovers how their son was murdered, as well as the identities of the killers. The documentary focuses on the youngest son, an optometrist named Adi, who decides to break the suffocating spell of submission and terror by doing something unimaginable in a society where the murderers remain in power: he confronts the men who killed his brother and, while testing their eyesight, asks them to accept responsibility for their actions. This unprecedented film initiates and bears witness to the collapse of fifty years of silence

Non-equilibrium chemistry and cooling in the diffuse interstellar medium - I. Optically thin regime

An accurate treatment of the multiphase interstellar medium (ISM) in hydrodynamic galaxy simulations requires that we follow not only the thermal evolution of the gas, but also the evolution of its chemical state, including its molecular chemistry, without assuming chemical (including ionisation) equilibrium. We present a reaction network that can be used to solve for this thermo-chemical evolution. Our model follows the evolution of all ionisation states of the 11 elements that dominate the cooling rate, along with important molecules such as H2 and CO, and the intermediate molecular species that are involved in their formation (20 molecules in total). We include chemical reactions on dust grains, thermal processes involving dust, cosmic ray ionisation and heating and photochemical reactions. We focus on conditions typical for the diffuse ISM, with densities of 10^-2 cm^-3 < nH < 10^4 cm^-3 and temperatures of 10^2 K < T < 10^4 K, and we consider a range of radiation fields, including no UV radiation. In this paper we consider only gas that is optically thin, while paper II considers gas that becomes shielded from the radiation field. We verify the accuracy of our model by comparing chemical abundances and cooling functions in chemical equilibrium with the photoionisation code Cloudy. We identify the major coolants in diffuse interstellar gas to be CII, SiII and FeII, along with OI and H2 at densities nH > 10^2 cm^-3. Finally, we investigate the impact of non-equilibrium chemistry on the cooling functions of isochorically or isobarically cooling gas. We find that, at T < 10^4 K, recombination lags increase the electron abundance above its equilibrium value at a given temperature, which can enhance the cooling rate by up to two orders of magnitude. The cooling gas also shows lower H2 abundances than in equilibrium, by up to an order of magnitude.Comment: 26 pages, 13 figures, accepted for publication in MNRAS. Corrected an error in figure 2. Supplementary material can be found at http://noneqism.strw.leidenuniv.n

Ecological relationships between marine microorganisms and hydrocarbons in the OEI study area, Louisiana

Supported by Gulf Universities Research Consortium, Project #OE73HJMCataloged from imperfect copy: all after leaf 20 wantingSeven cruise projects were conducted in association with the Louisiana Offshore Ecological Investigation (OEI) to determine the relationships between microorganisms and hydrocarbons in surface waters. Techniques were developed to take surface samples and to determine bacterial numbers, hydrocarbon content, and the response of indigenous microorganisms to various added hydrocarbon molecules. The numbers of heterotrophic bacteria as determined by dilution techniques varied from 10 to 10,000 per ml. The hydrocarbon oxidizing organisms varied from 10 to 100,000 per liter with maxima in the month of January. Hydrocarbon concentrations varied from 0.03 to 0.6 micrograms per liter. There was no correlation between the numbers of oil degraders and hydrocarbon concentration found. This may be the result of the in situ low concentrations of hydrocarbons which would limit microbial response. The numbers of bacteria and hydrocarbons were similar to control areas in the eastern and western parts of the Gulf. BOD experiments conducted to measure the response of the microorganisms to various low and high molecular weight paraffinic and aromatic hydrocarbons indicated that all hydrocarbons were oxidized by some of the mixed indigenous microorganisms. These data suggest that an adequate inoculum was naturally present to respond to oil contamination in nature. The high numbers of hydrocarbon oxidizing microorganisms associated with January hydrographic data may indicate that the upland leaching and other contamination of hydrocarbons in the Mississippi River produce the noted microbial response for that month. The dominant saturated hydrocarbons and isoprenoids ranged from C-15 to C-41. Water from Timbalier Bay generally contained higher concentrations than offshore samples and exhibited a more pronounced odd-even preference in the range C-24 to C-33. GC-MS analysis of the dominant paraffins revealed a characteristic biomodal distribution dominated by C-17 and pristane and C-25 to C-35 with an unresolved envelope. No buildup of specific n-paraffin molecules was found, which data corresponded to BOD results of added hydrocarbons to indigenous microflora.Marine Scienc

NICMOS2 hubble space telescope observations of the embedded cluster associated with Mon R2: Constraining the substellar initial mass function

We have analyzed Hubble Space Telescope NICMOS2 F110W-, F160W-, F165M-, and F207M-band images covering the central 1' × 1' region of the cluster associated with Mon R2 in order to constrain the initial mass function (IMF) down to 20M_J. The flux ratio between the F165M and F160W bands was used to measure the strength of the water-band absorption feature and select a sample of 12 out of the total sample of 181 objects that have effective temperatures between 2700 and 3300 K. These objects are placed in the H-R diagram together with sources observed by Carpenter et al. to estimate an age of ~1 Myr for the low-mass cluster population. By constructing extinction-limited samples, we are able to constrain the IMF and the fraction of stars with a circumstellar disk in a sample that is 90% complete for both high- and low-mass objects. For stars with estimated masses between 0.1 and 1.0 M_☉ for a 1 Myr population with A_V ≤ 19 mag, we find that 27% ± 9% have a near-infrared excess indicative of a circumstellar disk. The derived fraction is similar to or slightly lower than the fraction found in other star-forming regions of comparable age. We constrain the number of stars in the mass interval 0.08-1.0 M_☉ to the number of objects in the mass interval 0.02-0.08 M_☉ by forming the ratio R^(**) = N(0.08-1 M_☉)/N(0.02-0.08 M_☉) for objects in an extinction-limited sample complete for A_V ≤ 7 mag. The ratio is found to be R^(**) = 2.2 ± 1.3, assuming an age of 1 Myr, consistent with the similar ratio predicted by the system IMF proposed by Chabrier. The ratio is similar to the ratios observed toward the Orion Nebula Cluster and IC 348, as well as the ratio derived in the 28 deg^2 survey of Taurus by Guieu et al

You Take the High Road, and I’ll Take the Low Road:Evaluating the Topographical Consistency of Cognitive Models

We present a novel framework for assessing the fit of cogni-tive models. Using this framework, we highlight limitationsof existing methods of model evaluation, and derive new ap-proaches to validating cognitive models. Tests of topographi-cal consistency emphasize how a model’s structure constrainsbehavior on pairs of coupled stimuli, even when point predic-tions on individual stimuli depend on estimates of the model’sfree parameters. By carefully selecting these coupled stim-uli such that they follow the distinct topography of the model,researchers can overcome some limitations of existing meth-ods. Finally, we provide a proof-of-concept example of how touse our approach to assess a model of multi-alternative, multi-attribute choice