Predicting the Output From a Stochastic Computer Model When a Deterministic Approximation is Available

The analysis of computer models can be aided by the construction of surrogate models, or emulators, that statistically model the numerical computer model. Increasingly, computer models are becoming stochastic, yielding different outputs each time they are run, even if the same input values are used. Stochastic computer models are more difficult to analyse and more difficult to emulate - often requiring substantially more computer model runs to fit. We present a method of using deterministic approximations of the computer model to better construct an emulator. The method is applied to numerous toy examples, as well as an idealistic epidemiology model, and a model from the building performance field

Carbon and Oxygen Isotope Fractionation in Laboratory-Precipitated, Inorganic Calcite

Carbon and oxygen isotopes in calcite crystals provide a record of the environmental conditions under which the crystals formed. To investigate the influence of temperature, pH, and growth rate on isotope discrimination by calcite, we measured carbon and oxygen isotope fractionation through a series of calcite precipitation experiments at T = 25C and pH = 7.5 - 9.3. We observe that neither the carbon nor oxygen isotope compositions correspond to the theoretical equilibrium isotope fractionation between calcite and solution. We also demonstrate that the fractionation of oxygen isotopes between calcite and water decreases with increasing pH, consistent with available data from experiments in which the enzyme carbonic anhydrase was used. Finally, we compare the carbon and oxygen isotopes of our calcite crystals to those of biogenic carbonates. This thesis includes previously unpublished co-authored material

Letter from Evan Baker to Senator Langer Regarding the Selling of Fort Berthold Reservation Land, March 31, 1948

This letter dated August 31, 1948, from Evan Baker to United States (US) Senator William Langer, informs Langer that Baker is “an Indian of the Fort Berthold Reservation” and would like to sell 160 acres of his land. Baker writes that his home isn’t suitable for his large family and would like to build a better home and buy cattle with the money from the sale of the land. adding that the land he plans to sell will be isolated from him by the Garrison Dam, so he might as well get something out of it while he can. Baker writes that he has found a buyer for the land but the Indian Office will not help him. He adds that he has been rejected for loans on three different occasions. See also: Letter from Senator Langer to Evan Baker Expressing Delight in Helping to Sell Fort Berthold Reservation Land, April 16, 1948https://commons.und.edu/langer-papers/1722/thumbnail.jp

Augmented Cocaine Seeking in Response to Stress or CRF Delivered into the Ventral Tegmental Area Following Long-Access Self-Administration Is Mediated by CRF Receptor Type 1 But Not CRF Receptor Type 2

Stressful events are determinants of relapse in recovering cocaine addicts. Excessive cocaine use may increase susceptibility to stressor-induced relapse through alterations in brain corticotropin-releasing factor (CRF) regulation of neurocircuitry involved in drug seeking. We previously reported that the reinstatement of cocaine seeking by a stressor (footshock) is CRF dependent and is augmented in rats that self-administered cocaine under long-access (LgA; 6 h daily) conditions for 14 d when compared with rats provided shorter daily cocaine access [short access (ShA) rats; 2 h daily]. Further, we have demonstrated that reinstatement in response to intracerebroventricular CRF administration is heightened in LgA rats. This study examined the role of altered ventral tegmental area (VTA) responsiveness to CRF in intake-dependent increases in CRF- and stress-induced cocaine seeking. Bilateral intra-VTA administration of CRF (250 or 500 ng/side) produced reinstatement in LgA but not ShA rats. In LgA rats, intra-VTA CRF-induced reinstatement was blocked by administration of the CRF-receptor type 1 (CRF-R1) antagonist antalarmin (500 ng/side) or CP-376395 (500 ng/side), but not the CRF-R2 antagonist astressin-2B (500 ng or 1 μg/side) or antisauvagine-30(ASV-30; 500 ng/side) into the VTA. Likewise, intra-VTA antalarmin, but not astressin-2B, blocked footshock-induced reinstatement in LgA rats. By contrast, neither intra-VTA antalarmin nor CP-376395 altered food-reinforced lever pressing. Intra-VTA injection of the CRF-R1-selective agonist cortagine (100 ng/side) but not the CRF-R2-selective agonist rat urocortin II (rUCN II; 250 ng/side) produced reinstatement. These findings reveal that excessive cocaine use increases susceptibility to stressor-induced relapse in part by augmenting CRF-R1-dependent regulation of addiction-related neurocircuitry in the VTA

Little creatures

As the Internet becomes increasingly embodied and made physical, our relationship with it inevitably changes. The Internet has also changed our relationship with each other, particularly as an enabler for collective endeavour. A project from Evan Raskob and Fiona French has brought all of this together, in the form of group-designed, digitally-enabled beings

Adjustable microchip ring trap for cold atoms and molecules

We describe the design and function of a circular magnetic waveguide produced from wires on a microchip for atom interferometry using deBroglie waves. The guide is a two-dimensional magnetic minimum for trapping weak-field seeking states of atoms or molecules with a magnetic dipole moment. The design consists of seven circular wires sharing a common radius. We describe the design, the time-dependent currents of the wires and show that it is possible to form a circular waveguide with adjustable height and gradient while minimizing perturbation resulting from leads or wire crossings. This maximal area geometry is suited for rotation sensing with atom interferometry via the Sagnac effect using either cold atoms, molecules and Bose-condensed systems