A Decision Theoretic Approach for Interface Agent Development

The complexity of current software applications is overwhelming users. The need exists for intelligent interface agents to address the problem of increasing taskload that is overwhelming the human user. Interface agents could help alleviate user taskload by extracting and analyzing relevant information, and providing information abstractions of that information, and providing timely, beneficial assistance to users. These agents could communicate with the user through the existing user interface and also adapt to user needs and behaviors. Central to providing assistance to a user is the issue of correctly determining the user\u27s intent. This dissertation presents an effective, efficient, and extensible decision-theoretic architecture for user intent ascription. The multi-agent architecture, the Core Interface Agent architecture, provides a dynamic, uncertainty-based knowledge representation for modeling the inherent ambiguity in ascribing user intent. The knowledge representation, a Bayesian network, provides an intuitive, mathematically sound way of determining the likelihood a user is pursuing a goal. This likelihood, combined with the utility of offering assistance to the user, provides a decision-theoretic approach to offering assistance to the user. The architecture maintains an accurate user model of the user\u27s goals within a target system environment. The on-line maintenance of the user model is performed by a collection of correction adaptation agents. Because the decision-theoretic methodology is domain-independent, this new methodology for user intent ascription is readily extensible over new application domains. Furthermore, it also offers the ability to bootstrap intent understanding without the need for often lengthy and costly knowledge elicitation. Thus, as a side benefit, the process can mitigate the classic knowledge acquisition bottleneck problem

Controls on Terrestrial Evapotranspiration from a Forest-Wetland Complex in the Western Boreal Plain, Alberta, Canada

The Western Boreal Plain (WBP) of North Central Alberta consists of a mosaic wetlands and aspen (Populus tremuloides) dominated uplands. This region operates within a moisture deficit regime where precipitation (P) and evapotranspiration (ET) are the dominant hydrologic fluxes. As such these systems are extremely susceptible to the slightest to the slightest climatic variability that may upset the balance between P and ET. Vegetation composition is the dominant control on wetland ET, and itself is extremely dynamic within these wetland environments, which can be attributed to varying moisture regimes along with micrometeorological variations. To address this variability in moisture regimes ET was examined in a typical moraine wetland of the WBP during the 2005 and 2006 snow-free seasons. Closed dynamic chamber measurements were used to gather data on plant community scale actual evapotranspiration (ET) for an undisturbed natural bog with varying degrees of canopy cover surrounding a shallow groundwater fed pond. For the purposes of scaling plant community ET contributions to that of the wetland, potential ET (PETEQ) was measured using a Priestley-Taylor energy balance approach at three separate wetland sites with varying aspects surrounding the central pond, along with actual ET using a roving eddy covariance (EC) tower. Growing season peak ET rates ranged from 0.2 mm hr-1 to 0.6 mm hr-1 depending on location, vegetation composition and time period. Sphagnum contributions were the greatest early in the growing season reaching peaks of 0.6 mm hr-1, while lichen sites exhibited the greatest late season rates at 0.4 mm hr-1. Thus, Sphagnum and other non-vascular wetland plant species control ET differently throughout the growing season and as such should be considered an integral part of the moisture and water balances within wetland environments at the sub-landcover unit scale. Upland ET was characterized over three scales during the 2005 and 2006 snowfree seasons. Above canopy (ETC) and within canopy (ETB) were examined using the EC technique situated at 25.5 m (7.5 m above crown) and 4.0 m above the ground surface respectively. Soil evaporation (ES) was examined using a closed dynamic chamber system to gather data on surface evaporation for upland soils. ETc and ETB were controlled primarily through atmospheric demand (VPD) while Es was controlled by soil moisture (9). During the green periods ETC averaged 3.08 mm d-1 and 3.45 mm d-1 in 2005 and 2006 respectively while ETB averaged 1.56 mm d-1 and 1.95 mm d-1. Es was consistent across both snow-free seasons and averaged 0.28 mm hr-1 in 2005 and 0.31 mm hr-1 in 2006. The nature of Populus tremuloides canopies permits ample energy availability within the canopy during the early season early green periods which promotes the development of a lush understory consisting of Rosa acicularis and Viburnum edule. ETB fluxes were equal to or greater than the ETC fluxes once understory development had occurred. Upon crown growth ETB fluxes were reduced as a reduction in available energy existed. ETB fluxes ranged from 42 to 56% of ETC fluxes over the remainder of the snowfree seasons. Vapour pressure deficit (VPD) and soil moisture (0) displayed strong controls on both ETc and ETB fluxes. ETc fluxes responded to precipitation events as the developed crown intercepted and held available water which contributed to peak ETC fluxes following precipitation events \u3e10 mm. This indicates the importance of interception in aspen dominated forest canopies of the WBF

A heterogeneous-agent model with district-level constraints: an application to livestock development in Gansu, China

This paper develops a heterogeneous-agent model to assess the impacts of removing lucerne growing subsidies, increasing livestock numbers and including district-level equilibrium conditions on optimal farm plans in the Qingyang district of Gansu Province, China. The model is a five-year dynamic linear program that solves across 96 farm households whilst incorporating district-level constraints. The approach used allows us to observe seasonal variations in incomes, infer the distribution of a policy shock among households and highlight trade patterns at the district level. The results suggest that without lucerne growing subsidies the total area of lucerne grown by all modelled households falls by 18%. Increasing livestock numbers by 25% reduces net household incomes by 17% as changes to labour allocations reduce off-farm employment opportunities. When external trade in forages is included in the model, total livestock numbers held by all 96 households rise from 502 to 838, this highlights the benefits of integrated feed markets. Shadow prices for crop production rise when livestock numbers increase, implying that benefits exist to improving crop yields.Heterogeneous-agent model, district-level constraints, livestock, China., Farm Management,

Kepler and the Kuiper Belt

The proposed field-of-view of the Kepler mission is at an ecliptic latitude of ~55 degrees, where the surface density of scattered Kuiper Belt Objects (KBOs) is a few percent that in the ecliptic plane. The rate of occultations of Kepler target stars by scattered KBOs with radii r>10km is ~10^-6 to 10^-4 per star per year, where the uncertainty reflects the current ignorance of the thickness of the scattered KBO disk and the faint-end slope of their magnitude distribution. These occultation events will last only ~0.1% of the planned t_exp=15 minute integration time, and thus will appear as single data points that deviate by tiny amounts. However, given the target photometric accuracy of Kepler, these deviations will nevertheless be highly significant, with typical signal-to-noise ratios of ~10. I estimate that 1-20 of the 10^5 main-sequence stars in Kepler's field-of-view will exhibit detectable occultations during its four-year mission. For unresolved events, the signal-to-noise of individual occultations scales as t_exp^{-1/2}, and the minimum detectable radius could be decreased by an order of magnitude to ~1 km by searching the individual 3-second readouts for occultations. I propose a number of methods by which occultation events may be differentiated from systematic effects. Kepler should measure or significantly constrain the frequency of highly-inclined, ~10 km-sized KBOs.Comment: 5 pages, 1 figure. No changes. Accepted to ApJ, to appear in the August 1, 2004 issue (v610

Astrometric Microlensing Constraints on a Massive Body in the Outer Solar System with Gaia

A body in Solar orbit beyond the Kuiper belt exhibits an annual parallax that exceeds its apparent proper motion by up to many orders of magnitude. Apparent motion of this body along the parallactic ellipse will deflect the angular position of background stars due to astrometric microlensing ("induced parallax"). By synoptically sampling the astrometric position of background stars over the entire sky, constraints on the existence (and basic properties) of a massive nearby body may be inferred. With a simple simulation, we estimate the signal-to-noise for detecting such a body -- as function of mass, heliocentric distance, and ecliptic latitude -- using the anticipated sensitivity and temporal cadences from Gaia (launch 2011). A Jupiter-mass (M_Jup) object at 2000 AU is detectable by Gaia over the whole sky above 5-sigma, with even stronger constraints if it lies near the ecliptic plane. Hypotheses for the mass (~3M_Jup), distance (~20,000 AU) and location of the proposed perturber ("Planet X") which gives rise to long-period comets may be testable.Comment: 17 pages, 6 figures. Figures revised, new figure added, minor text revisions. Accepted to ApJ, to appear in the Dec 10, 2005 issue (v635

Sensitivity of IceCube-DeepCore to neutralino dark matter in the MSSM-25

We analyse the sensitivity of IceCube-DeepCore to annihilation of neutralino dark matter in the solar core, generated within a 25 parameter version of the minimally supersymmetric standard model (MSSM-25). We explore the 25-dimensional parameter space using scanning methods based on importance sampling and using DarkSUSY 5.0.6 to calculate observables. Our scans produced a database of 6.02 million parameter space points with neutralino dark matter consistent with the relic density implied by WMAP 7-year data, as well as with accelerator searches. We performed a model exclusion analysis upon these points using the expected capabilities of the IceCube-DeepCore Neutrino Telescope. We show that IceCube-DeepCore will be sensitive to a number of models that are not accessible to direct detection experiments such as SIMPLE, COUPP and XENON100, indirect detection using Fermi-LAT observations of dwarf spheroidal galaxies, nor to current LHC searches.Comment: 15 pages, 13 figures. V2: Additional comparisons are made to limits from Fermi-LAT observations of dwarf spheroidal galaxies and to the 125 GeV Higgs signal from the LHC. The spectral hardness section has been removed. Matches version accepted for publication in JCAP. V3: Typos correcte

Liver Transplantation to Provide Low-Density-Lipoprotein Receptors and Lower Plasma Cholesterol in a Child with Homozygous Familial Hypercholesterolemia

A six-year-old girl with severe hypercholesterolemia and atherosclerosis had two defective genes at the low-density-lipoprotein (LDL) receptor locus, as determined by biochemical studies of cultured fibroblasts. One gene, inherited from the mother, produced no LDL receptors; the other gene, inherited from the father, produced a receptor precursor that was not transported to the cell surface and was unable to bind LDL. The patient degraded intravenously administered 125I-LDL at an extremely low rate, indicating that her high plasma LDL-cholesterol level was caused by defective receptor-mediated removal of LDL from plasma. After transplantation of a liver and a heart from a normal donor, the patient's plasma LDL-cholesterol level declined by 81 per cent, from 988 to 184 mg per deciliter. The fractional catabolic rate for intravenously administered 125I-LDL, a measure of functional LDL receptors in vivo, increased by 2.5-fold. Thus, the transplanted liver, with its normal complement of LDL receptors, was able to remove LDL cholesterol from plasma at a nearly normal rate. We conclude that a genetically determined deficiency of LDL receptors can be largely reversed by liver transplantation. These data underscore the importance of hepatic LDL receptors in controlling the plasma level of LDL cholesterol in human beings. (N Engl J Med 1984; 311: 1658–64.). © 1984, Massachusetts Medical Society. All rights reserved

Neutrons transition densities for the 2+−8+2^+-8^+ multiplet of states in 90^{90}Zr

The neutron transition densities of the $2^+-8^+$ levels in $^{90}$Zr were extracted in the process of analysing ({\bf p},p') scattering at 400 Mev. Its comparison with the proton transition densities for these levels was undertaken. The radial shapes of the experimental neutron and proton transition densities for each state were found to be different.Comment: 9 pages, 4 figure

Defective cAMP generation underlies the sensitivity of CNS neurons to neurofibromatosis-1 heterozygosity

Individuals with the Neurofibromatosis-1 (NF1) inherited cancer syndrome exhibit neuronal dysfunction that predominantly affects the central nervous system (CNS). In this report, we demonstrate a unique vulnerability of CNS neurons, but not peripheral nervous system (PNS) neurons, to reduced Nf1 gene expression. Unlike dorsal root ganglion neurons, Nf1 heterozygous (Nf1+/−) hippocampal and retinal ganglion cell (RGC) neurons have decreased growth cone areas and neurite lengths, and increased apoptosis compared to their wild-type counterparts. These abnormal Nf1+/− CNS neuronal phenotypes do not reflect Ras pathway hyperactivation, but rather result from impaired neurofibromin-mediated cAMP generation. In this regard, elevating cAMP levels with forskolin or rolipram treatment, but not MEK or PI3-K inhibition, reverses these abnormalities to wild-type levels in vitro. In addition, Nf1+/− CNS, but not PNS, neurons exhibit increased apoptosis in response to excitotoxic or oxidative stress in vitro. Since children with NF1-associated optic gliomas often develop visual loss and Nf1 genetically-engineered mice with optic glioma exhibit RGC neuronal apoptosis in vivo, we further demonstrate that RGC apoptosis resulting from optic glioma in Nf1 genetically-engineered mice is attenuated by rolipram treatment in vivo. Similar to optic glioma-induced RGC apoptosis, the increased RGC neuronal death in Nf1+/− mice following optic nerve crush injury is also attenuated by rolipram treatment in vivo. Together, these findings establish a distinctive role for neurofibromin in CNS neurons with respect to vulnerability to injury, define a CNS-specific neurofibromin intracellular signaling pathway responsible for neuronal survival, and lay the foundation for future neuroprotective glioma treatment approaches