An improved approach to reinforcement learning in computer go

Monte-Carlo Tree Search (MCTS) has revolutionized, Computer Go, with programs based on the algorithm, achieving a level of play that previously seemed decades away., However, since the technique involves constructing a search tree, its performance t

Large-area submillimeter resolution CdZnTe strip detector for astronomy

We report the first performance measurements of a sub-millimeter CdZnTe strip detector developed as a prototype for space-borne astronomical instruments. Strip detector arrays can be used to provide two-dimensional position resolution with fewer electronic channels than pixellated arrays. Arrays of this type and other candidate technologies are under investigation for the position-sensitive backplane detector for a coded-aperture telescope operating in the range of 30 - 300 keV. The prototype is a 1.4 mm thick, 64 multiplied by 64 stripe CdZnTe array of 0.375 mm pitch in both dimensions, approximately one square inch of sensitive area. Pulse height spectra in both single and orthogonal stripe coincidence mode were recorded at several energies. The results are compared to slab- and pixel-geometry detector spectra. The room-temperature energy resolution is less than 10 keV (FWHM) for 122 keV photons with a peak-to-valley ratio greater than 5:1. The response to photons with energies up to 662 keV appears to be considerably improved relative to that of previously reported slab and pixel detectors. We also show that strip detectors can yield spatial and energy resolutions similar to those of pixellated arrays with the same dimensions. Electrostatic effects on the pulse heights, read-out circuit complexity, and issues related to design of space borne instruments are also discussed

Mössbauer characterisation of synthetic analogues of the helvite minerals Fe4M4[BeSiO4]6X2, (M=Fe, Mn, Zn; X=S, Se)

We report on this paper on the Mossbauer characterisation of the family of synthetic helvite analogues, Fe4M4[BeSiO4]6X2 (M = Fe, Mn, Zn; X = S, Se). The data show iron to be present as high spin Fe(II) in tetrahedral coordination. The room temperature Mossbauer spectra are composed either by singlets or doublets with small quadrupole splitting values suggesting a small valence contribution at that temperature. From the dependence of the quadrupole splitting with temperature the separation Δ between the two eg orbitals has been estimated. The values of Δ range from 46.3 cm− 1 for the material Fe8[BeSiO4]6S2 to 58.2 cm1 for the material Fe4Zn4[BeSiO4]6S2. The lack of long-range magnetic order observed in the Mossbauer spectra was confirmed by neutron diffraction data which suggests that the M4X units are largely magnetically isolated within their cages leading to a frustrated magnet with no long range interaction for the sulfide species

Development of an orthogonal-stripe CdZnTe gamma radiation imaging spectrometer

We report performance measurements of a sub-millimeter resolution CdZnTe strip detector developed as a prototype for astronomical instruments operating with good efficiency in the 30-300 keV photon energy range. The prototype is a 1.4 mm thick, 64×64 contact stripe CdZnTe array of 0.375 mm pitch in both dimensions. Pulse height spectra were recorded in orthogonal-stripe coincidence mode which demonstrate room-temperature energy resolution \u3c10 keV (FWHM) for 122 keV photons with a peak-to-valley ratio \u3e5:1. Good response is also demonstrated at higher energies using a coplanar grid readout configuration. Spatial resolution capabilities finer than the stripe pitch are demonstrated. We present the image of a 133Ba source viewed through a collimator slit produced by a 4×4 stripe detector segment. Charge signals from electron and hole collecting contacts are also discussed

Diet segregation between two colonies of little penguins Eudyptula minor in southeast Australia

We studied foraging segregation between two different sized colonies of little penguins Eudyptula minor with overlapping foraging areas in pre-laying and incubation. We used stomach contents and stable isotope measurements of nitrogen (δ 15N) and carbon (δ 13C) in blood to examine differences in trophic position, prey-size and nutritional values between the two colonies. Diet of little penguins at St Kilda (small colony) relied heavily on anchovy while at Phillip Island (large colony), the diet was more diverse and anchovies were larger than those consumed by St Kilda penguins. Higher δ 15N values at St Kilda, differences in δ 13C values and the prey composition provided further evidence of diet segregation between colonies. Penguins from each colony took anchovies from different cohorts and probably different stocks, although these sites are only 70km apart. Differences in diet were not reflected in protein levels in the blood of penguins, suggesting that variation in prey between colonies was not related to differences in nutritional value of the diet. Anchovy is currently the only available prey to penguins throughout the year and its absence could have a negative impact on penguin food supply, particularly at St Kilda where the diet is dominated by this species. While it is difficult to establish whether diet segregation is caused by inter- or intra-colony competition or spatial differences in foraging areas, we have shown that colonies with broadly overlapping foraging ranges could have significant differences in trophic position, diet composition and prey size while maintaining a diet of similar nutritional value. © 2011 The Authors. Austral Ecology © 2011 Ecological Society of Australia.Peer Reviewe

Supplementary information files for An iron ore-based catalyst for producing hydrogen and metallurgical carbon via catalytic methane pyrolysis for decarbonisation of the steel industry

Supplementary files for article An iron ore-based catalyst for producing hydrogen and metallurgical carbon via catalytic methane pyrolysis for decarbonisation of the steel industry Experiments to investigate the catalytic pyrolysis of methane using an iron ore-based catalyst were carried out to optimize catalytic activity and examine the purity of the carbon produced from the process for the first time. Ball milling of the iron ore at 300 rpm for varying times – from 30 to 330 minutes – was studied to determine the effect of milling time on methane conversion. Optimal milling for 270 minutes led to a five-fold increase in methane conversion from ca. 1% to 5%. Further grinding resulted in a decline of methane conversion to 4% shown by SEM to correspond to an increase in particle size caused by agglomeration. Data from Raman and Mössbauer spectroscopy and H2 temperature programmed reduction indicated a change in phase from magnetite to maghemite and hematite (at the particle surface) as the grinding time increased. Analysis of the carbon produced as a byproduct of the reaction indicated a highly pure material with the potential to be used as an additive for steel production. </p

The Future of Targeted Therapy for Leiomyosarcoma

Leiomyosarcoma (LMS) is an aggressive subtype of soft tissue sarcoma that arises from smooth muscle cells, most commonly in the uterus and retroperitoneum. LMS is a heterogeneous disease with diverse clinical and molecular characteristics that have yet to be fully understood. Molecular profiling has uncovered possible targets amenable to treatment, though this has yet to translate into approved targeted therapies in LMS. This review will explore historic and recent findings from molecular profiling, highlight promising avenues of current investigation, and suggest possible future strategies to move toward the goal of molecularly matched treatment of LMS. We focus on targeting the DNA damage response, the macrophage-rich micro-environment, the PI3K/mTOR pathway, epigenetic regulators, and telomere biology

Upgrade of the X3 super-orbital expansion tube

Expansion tubes are important facilities for the study of high enthalpy hypersonic flows which avoid the non-equilibrium chemical and thermal effects associated with the flow stagnation intrinsic to reflected shock tunnels. X3 is one of the largest freepiston super-orbital expansion tube in the world with an overall length of approximately 69 m and is capable of generating reentry speed flows equivalent to those experienced during a hyperbolic re-entry trajectory. It was originally built with a twostage free-piston driver to achieve the high compression ratio of a large diameter compression tube without the high construction costs of designing the large diameter tube to be strong enough to resist peak driver pressure loads. However, this arrangement proved difficult in operation. This paper describes the upgrades to X3, in respect to its physical layout. The facility has been recommissioned to incorporate a single-piston driver, a steady expansion nozzle and a new test section. Major changes have been made to the free-piston driver with a re-designed piston and launcher and a new end cap tube which is 200 mm thick to contain driver pressures up to 80 MPa. The re-designed piston introduces an area change at the primary diaphragm, ensuring that the maximum increase in total pressure and temperature can be gained as the driver gas undergoes unsteady expansion from sonic to supersonic conditions. The compression process steadily increases up to Mach 1 at the throat then gains of up to an order of magnitude in total temperature and pressure can be realised as the unsteady expansion process takes over. The area change will also increase test times; with a throat at the primary diaphragm, the piston mechanics can be more readily tuned to minimise reflection of waves off the piston which would otherwise reduce the test time. A new Mach 10 steady expansion nozzle has been developed which has increased the core flow and the test time for appropriate conditions. The dump tank has been replaced with a larger tank and test section giving a larger volume with greater potential for instrumentation

Reusing skills for first-time solution of navigation tasks in platform videogames

We consider the problem of performing real-time navigation in domains where a &quot;god&#039;s eye view&quot;is provided. One setting where this challenge arises is in platform videogames, occurring whenever the player wishes to reach an item or powerup on the current screen. Previous agents for these games rely on generating many low-level simulations or training runs for each fixed task. Human players, on the other hand, can solve navigation tasks at a high level by visualising sequences of abstract &quot;skills&quot;. Based on this intuition, we introduce a novel planning approach and apply it to Infinite Mario. Despite facing randomly generated, maze-like tasks, our agent is capable of deriving complex plans in real-time, without exploiting precise knowledge of the game&#039;s code