Evaluating a Pattern-Based Visual Support Approach for Humanitarian Landmine Clearance

Unexploded landmines have severe post-conflict humanitarian repercussions: landmines cost lives, limbs and land. For deminers engaged in humanitarian landmine clearance, metal detectors remain the primary detection tool as more sophisticated technologies fail to get adopted due to restrictive cost, low reliability, and limited robustness. Metal detectors are, however, of limited effectiveness, as modern landmines contain only minimal amounts of metal, making them difficult to distinguish from the ubiquitous but harmless metallic clutter littering post-combat areas. We seek to improve the safety and efficiency of the demining process by developing support tools that will enable deminers to make better decisions using feedback from existing metal detectors. To this end, in this paper we propose and evaluate a novel, pattern-based visual support approach inspired by the documented strategies employed by expert deminers. In our laboratory study, participants provided with a prototype of our support tool were 80% less likely to mistake a mine for harmless clutter. A follow-up study demonstrates the potential of our pattern-based approach to enable peer decision-making support during landmine clearance. Lastly, we identify several design opportunities for further improving deminers' decision making capabilities.Engineering and Applied Science

Spectrum of Doubly Ionized Xenon (Xe III)

The spectrum of doubly ionized xenon has been investigated. The study is based on photographic recordings of xenon spectra in the 490-8900 Å range. The number of classified lines has been increased from about 300 to about 1400. The lines have been classified as transitions between 73 even levels belonging to the 5s25p4, 5s25p36p, 4ϕ, 5ϕ and 5s05p6 configurations, and 83 odd levels belonging to the 5s5p5, 5s25p36s, 7s, 5d and 6d configurations. In particular, the classifications include most of the Xe III laser lines. The experimentally observed level structures are compared with the results of Hartree-Fock calculations and least-squares fits. A comparison is also made between the results of the present analysis and the published data on the Xe N4,5OO Auger spectrumFacultad de Ciencias ExactasCentro de Investigaciones Óptica

Spectrum of Doubly Ionized Xenon (Xe III)

The spectrum of doubly ionized xenon has been investigated. The study is based on photographic recordings of xenon spectra in the 490-8900 Å range. The number of classified lines has been increased from about 300 to about 1400. The lines have been classified as transitions between 73 even levels belonging to the 5s25p4, 5s25p36p, 4ϕ, 5ϕ and 5s05p6 configurations, and 83 odd levels belonging to the 5s5p5, 5s25p36s, 7s, 5d and 6d configurations. In particular, the classifications include most of the Xe III laser lines. The experimentally observed level structures are compared with the results of Hartree-Fock calculations and least-squares fits. A comparison is also made between the results of the present analysis and the published data on the Xe N4,5OO Auger spectrumFacultad de Ciencias ExactasCentro de Investigaciones Óptica

Enhanced absorption Hanle effect on the Fg=F->Fe=F+1 closed transitions

We analyse the Hanle effect on a closed $F_g\to F_e=F_g+1$ transition. Two configurations are examined, for linear- and circular-polarized laser radiation, with the applied magnetic field collinear to the laser light wavevector. We describe the peculiarities of the Hanle signal for linearly-polarized laser excitation, characterized by narrow bright resonances at low laser intensities. The mechanism behind this effect is identified, and numerical solutions for the optical Bloch equations are presented for different transitions.Comment: to be published in J. Opt. B, special issue on Quantum Coherence and Entanglement (February 2001

Active Learning in Persistent Surveillance UAV Missions

The performance of many complex UAV decision-making problems can be extremely sensitive to small errors in the model parameters. One way of mitigating this sensitivity is by designing algorithms that more effectively learn the model throughout the course of a mission. This paper addresses this important problem by considering model uncertainty in a multi-agent Markov Decision Process (MDP) and using an active learning approach to quickly learn transition model parameters. We build on previous research that allowed UAVs to passively update model parameter estimates by incorporating new state transition observations. In this work, however, the UAVs choose to actively reduce the uncertainty in their model parameters by taking exploratory and informative actions. These actions result in a faster adaptation and, by explicitly accounting for UAV fuel dynamics, also mitigates the risk of the exploration. This paper compares the nominal, passive learning approach against two methods for incorporating active learning into the MDP framework: (1) All state transitions are rewarded equally, and (2) State transition rewards are weighted according to the expected resulting reduction in the variance of the model parameter. In both cases, agent behaviors emerge that enable faster convergence of the uncertain model parameters to their true values

Effect of Celergen, a marine derivative, on in vitro hepatocarcinogenesis

The aim of this study was to test for a potential anticarcinogenic effect of Celergen, a marine derivative devoid of traceable amounts of inorganic arsenic, on cell proliferation, cell cycle progression and apoptosis in the HepG2 human liver cancer cell line. Celergen significantly inhibited the proliferation of cancer cells in a dose-dependent manner while limiting the cell cycle progression at the G1 phase and significantly inducing apoptosis. Further examination showed that Celergen enhanced expression of the p21CIPl1WAF1, GADD153 genes and downregulated the c-myc gene. These results suggest that Celergen exerts promising chemopreventive properties to be further investigated

Ground-Based Ultraviolet-Radiation Measurements during Springtime in the Southern Hemisphere

We report the first measurements obtained by a network of UV-B detectors established through Argentina and Chile, at locations covering latitudes extending from 53°S to 18° S. Evidence that UVB increases are detected at these latitudes during the Austral spring 1993 is presented

Ground-based ultraviolet-radiation measurements during springtime in the Southern hemisphere

We report the first measurements obtained by a network of UV-B detectors established through Argentina and Chile, at locations covering latitudes extending from 53°S to 18° S. Evidence that UVB increases are detected at these latitudes during the Austral spring 1993 is presented. The destruction of the stratospheric ozone layer is generally considered one of the most serious environmental problems. It has been recently published that during October 1998 the ozone hole has been the deepest ever recorded. Reduction of the stratospheric ozone layer was un ambiguously detected about two decades ago in the Antarctic continent. Since then it has been systematically monitored by different means (satellite, balloon soundings and ground station observations. One of the most serious content reduction is the increase of biologically effective ultraviolet doses, particularly the so-called ultraviolet B radiation (280-320 nm) received at the Earth surface, with multiple possible hazards for living species. Despite these consequences, ground stations to check the UV Sun radiation are not very numerous, particularly outside the circumpolar area in the Southern Hemisphere. With the aim of studying whether the ozone depletion over the Antarctic area has extended further, and whether the possibility that UV radiation increase may begin to affect inhabited regions, a network of UVB detectors has been established through Argentina and Chile, at locations covering latitudes extending from 53°S to 18° S. Here we report the first measurements obtained by this network providing evidence that UVB increases are detected at these latitudes during the last Austral spring.Facultad de Ciencias Exacta

Ground-based ultraviolet-radiation measurements during springtime in the Southern hemisphere

We report the first measurements obtained by a network of UV-B detectors established through Argentina and Chile, at locations covering latitudes extending from 53°S to 18° S. Evidence that UVB increases are detected at these latitudes during the Austral spring 1993 is presented. The destruction of the stratospheric ozone layer is generally considered one of the most serious environmental problems. It has been recently published that during October 1998 the ozone hole has been the deepest ever recorded. Reduction of the stratospheric ozone layer was un ambiguously detected about two decades ago in the Antarctic continent. Since then it has been systematically monitored by different means (satellite, balloon soundings and ground station observations. One of the most serious content reduction is the increase of biologically effective ultraviolet doses, particularly the so-called ultraviolet B radiation (280-320 nm) received at the Earth surface, with multiple possible hazards for living species. Despite these consequences, ground stations to check the UV Sun radiation are not very numerous, particularly outside the circumpolar area in the Southern Hemisphere. With the aim of studying whether the ozone depletion over the Antarctic area has extended further, and whether the possibility that UV radiation increase may begin to affect inhabited regions, a network of UVB detectors has been established through Argentina and Chile, at locations covering latitudes extending from 53°S to 18° S. Here we report the first measurements obtained by this network providing evidence that UVB increases are detected at these latitudes during the last Austral spring.Facultad de Ciencias Exacta