Latent Self-Exciting Point Process Model for Spatial-Temporal Networks

We propose a latent self-exciting point process model that describes geographically distributed interactions between pairs of entities. In contrast to most existing approaches that assume fully observable interactions, here we consider a scenario where certain interaction events lack information about participants. Instead, this information needs to be inferred from the available observations. We develop an efficient approximate algorithm based on variational expectation-maximization to infer unknown participants in an event given the location and the time of the event. We validate the model on synthetic as well as real-world data, and obtain very promising results on the identity-inference task. We also use our model to predict the timing and participants of future events, and demonstrate that it compares favorably with baseline approaches.Comment: 20 pages, 6 figures (v3); 11 pages, 6 figures (v2); previous version appeared in the 9th Bayesian Modeling Applications Workshop, UAI'1

Thermal modeling of the TMT Telescope

Thermal modeling of the Thirty Meter Telescope (TMT) was conducted for evaluations of thermal performances by finite element (FE) and optical analysis tools. The thermal FE models consist of the telescope optical assembly systems, instruments, laser facility, control and electronic equipments, and telescope structural members. A three-consecutive-day thermal environment data was implemented for the thermal boundary created by Computational Fluid Dynamics (CFD) based on the environment conditions of the TMT site. Temporal and spatial temperature distributions of the optical assembly systems and the telescope structure were calculated under the environmental thermal conditions including air convections, conductions, heat flux loadings, and radiations. With the calculated temperature distributions, the thermo-elastic analysis was performed to predict thermal deformations of the telescope structure and the optical systems. The line of sight calculation was made using the thermally induced deformations of the optics and structures. Merit function routines (MFR) were utilized to calculate the Optical Path Difference (OPD) maps after repositioning the optics based on a best fit of M1 segment deformations. The goal of this thermal modeling is to integrate the mechanical and optical deformations in order to simulate the thermal effects with the TMT site environment data from CFD

Incentive Compatibility and Differentiability New Results and Classic Applications

We provide several generalizations of Mailath's (1987) result that in games of asymmetric information with a continuum of types incentive compatibility plus separation implies differentiability of the informed agent's strategy. The new results extend the theory to classic models in finance such as Leland and Pyle (1977), Glosten (1989), and DeMarzo and Duffie (1999), that were not previously covered

Phthalide annulation: the synthesis of kalafungin, pachybasin and chrysophanol

The anions of %cyano- or 3-(pheny1thio)phthalide react with Michael acceptors to afford functionalized naphthydroquinones in good yield. The cyano and phenylthio groups function both as activating groups and as leaving groups. An alternative involves the use of protected o-(carboxymethy1)cyanohydrins. The use of phthalide anions in synthesis is exemplified by total syntheses of kalafungin, pachybasin, and chrysophanol. This methodolgy consititutes a direct and regiospecific approach to polycyclic systems

Thermal performance prediction of the TMT optics

Thermal analysis for the Thirty Meter Telescope (TMT) optics (the primary mirror segment, the secondary mirror, and the tertiary mirror) was performed using finite element analysis in ANSYS and I-DEAS. In the thermal analysis, each of the optical assemblies (mirror, mirror supports, cell) was modeled for various thermal conditions including air convections, conductions, heat flux loadings, and radiations. The thermal time constant of each mirror was estimated and the temperature distributions of the mirror assemblies were calculated under the various thermal loading conditions. The thermo-elastic analysis was made to obtain the thermal deformation based on the resulting temperature distributions. The optical performance of the TMT optics was evaluated from the thermally induced mirror deformations. The goal of this thermal analysis is to establish thermal models by the FEA programs to simulate for an adequate thermal environment. These thermal models can be utilized for estimating the thermal responses of the TMT optics. In order to demonstrate the thermal responses, various sample time-dependent thermal loadings were modeled to synthesize the operational environment. Thermal responses of the optics were discussed and the optical consequences were evaluated

Perturbative calculation of quasi-normal modes of arbitrary spin in Schwarzschild spacetime

We calculate analytically the asymptotic form of quasi-normal modes of perturbations of arbitrary spin of a Schwarzschild black hole including first-order corrections. We use the Teukolsky equation which applies to both bosonic and fermionic modes. Remarkably, we arrive at explicit expressions which coincide with those derived using the Regge-Wheeler equation for integer spin. Our zeroth-order expressions agree with the results of WKB analysis. In the case of Dirac fermions, our results are in good agreement with numerical data.Comment: 13 pages incl. 3 figures, v2: corrected error, generalized results to arbitrary spi

Low Back Demand of Equipment Carriage Tasks in Golf

Low back injury is a common concern in golfers and caddies. The literature often points to the biomechanics of the golf swing as the major contributing factor; however, golfers and caddies can regularly walk upward of 10,000 steps on uneven terrain while carrying equipment, which can contribute to the cumulative load on the low back. PURPOSE: To examine the low back biomechanical demands during golf equipment carriage and pick-up tasks. METHODS: Sixteen golfers (11M/5F, 27.4±3.5yrs) participated in 3D motion capture of a golf bag pick-up task and 3 walking tasks (1. unloaded walking [UW], 2. unilateral carrying on the right shoulder [SS], and 3. carrying the golf bag across both shoulders [DS]); using an 11.3 kg duo-strap carry bag. Kinematic and Kinetic data were collected at 60Hz and 1500Hz, respectively, and filtered with a 6Hz lowpass filter. The lower extremity, pelvis, and trunk were modeled as ridgid segments, and lumbosacral (L5S1) kinematics and kinetics were calculated in Visual 3D. Peak internal moments were calculated via inverse dynamics and normalized to body weight. Descriptive statistics were calculated for sagittal and frontal plane peak L5S1 moments. Hedge’s g effect sizes were calculated for frontal plane bilateral peak moment differences in the pick-up task. RESULTS: The pick-up task yielded peak extensor moment of 1.14 ± 0.32 and peak left lateral flexor moment of 1.08 ± 0.27 Nm/Kg. Compared with peak right lateral flexor moment (0.09 ± 0.07 Nm/Kg), peak left lateral flexor was 12 times higher with a large effect size (g=2.77). In the walking conditions, peak extensor moment was highest in UW (0.28 ± 0.14 Nm/Kg) follow by SS (0.25 ± 0.2 Nm/Kg) then DS (0.07 ± 0.19 Nm/Kg). In contrast, peak flexor moments were highest in DS, followed by SS then UW. In the frontal plane, SS yielded peak left lateral flexor moment of 0.62 ± 0.14 Nm/Kg, which was 3 times higher than UW and more than twice higher than DS. CONCLUSION: The pick-up task is unilateral and yielded comparable peak L5S1 moments to the golf swing. Carrying the golf bag while walking alters the position of center of mass, which alters low back demands compared to unloaded walking. Due to the large number of cycles performed, equipment carriage tasks should be considered when estimating cumulative low back demand in golfers and caddies

Food Security & Civil Society

Findings from an in-depth qualitative investigation of Food Security with people from civil society organisations. A ‘boots on the ground’ perspective, which reveals the concerns about food security, and stakeholder evaluations of what they think needs to be done