Accelerating shrinkage of Patagonian glaciers from the Little Ice Age (∼AD 1870) to 2011

We used Little Ice Age (LIA) trimlines and moraines to assess changes in South American glaciers over the last ∼140 years. We determined the extent and length of 640 glaciers during the LIA (∼ AD 1870) and 626 glaciers (the remainder having entirely disappeared) in 1986, 2001 and 2011. The calculated reduction in glacierized area between the LIA and 2011 is 4131 km2 (15.4%), with 660 km2 (14.2%) being lost from the Northern Patagonia Icefield (NPI), 1643 km2 (11.4%) from the Southern Patagonia Icefield (SPI) and 306 km2 (14.4%) from Cordillera Darwin. Latitude, size and terminal environment (calving or land-terminating) exert the greatest control on rates of shrinkage. Small, northerly, land-terminating glaciers shrank fastest. Annual rates of area loss increased dramatically after 2001 for mountain glaciers north of 52° S and the large icefields, with the NPI and SPI now shrinking at 9.4 km2 a–1 (0.23% a–1) and 20.5 km2 a–1 (0.15% a–1) respectively. The shrinkage of glaciers between 52° S and 54° S accelerated after 1986, and rates of shrinkage from 1986 to 2011 remained steady. Icefield outlet glaciers, isolated glaciers and ice caps south of 54° S shrank faster from 1986 to 2001 than they did from 2001 to 2011.

Rapid preconditioning of data for accelerating convex hull algorithms

Given a dataset of two-dimensional points in the plane with integer coordinates, the method proposed reduces a set of n points down to a set of s points s ≤ n, such that the convex hull on the set of s points is the same as the convex hull of the original set of n points. The method is O(n). It helps any convex hull algorithm run faster. The empirical analysis of a practical case shows a percentage reduction in points of over 98%, that is reflected as a faster computation with a speedup factor of at least 4.

Quantized fields and gravitational particle creation in f (R) expanding universes

The problem of cosmological particle creation for a spatially flat, homogeneous and isotropic universes is discussed in the context of f (R) theories of gravity. Different from cosmological models based on general relativity theory, it is found that a conformal invariant metric does not forbid the creation of massless particles during the early stages (radiation era) of the universe. (C) 2010 Elsevier B.V. All rights reserved.

Accelerating linear causal model discovery using hoeffding bounds

Efficiently inducing precise causal models accurately reflecting given data sets is the ultimate goal of causal discovery. The algorithms proposed by Dai et al. has demonstrated the ability of the Minimum Message Length (MML) principle in discovering Linear Causal Models from training data. In order to further explore ways to improve efficiency, this paper incorporates the Hoeffding Bounds into the learning process. At each step of causal discovery, if a small number of data items is enough to distinguish the better model from the rest, the computation cost will be reduced by ignoring the other data items. Experiments with data set from related benchmark models indicate that the new algorithm achieves speedup over previous work in terms of learning efficiency while preserving the discovery accuracy.

Encoding, ensemble and accelerating strategies for linear causal model discovery

This thesis made outstanding contribution in automating the discovery of linear causal models. It introduced a highly efficient discovery algorithm, which implements new encoding, ensemble and accelerating strategies. Theoretic research and experimental work showed that this new discovery algorithm outperforms the previous system in both accuracy and efficiency.

Microscopic / telescopic (universes unfold)

This exhibition was inspired by lens based observation; what is observed through the microscope – plankton and single cell organisms – finds its origin in what is observed through the telescope – stars and galaxies. The project explores two spatially divergent contexts. Artist, Melinda Capp explores the micro-scopic with porcelain objects, artist books and images derived microscopes and Daniel Armstrong references the macro-scopic with video, photography, lens based objects and installation of interactive sculpture / optical instruments to create an experiential connection between celestial phenomena/images and the viewer.

Pd embedded in porous carbon (Pd@CMK-3) as an active catalyst for Suzuki reactions: accelerating mass transfer to enhance the reaction rate

Heterogeneous catalysts are promising candidates for use in organic reactions due to their advantages in separation, recovery, and environment compatibility. In this work, an active porous catalyst denoted as Pd embedded in porous carbon (Pd@CMK-3) has been prepared by a strategy involving immersion, ammoniahydrolysis, and heating procedures. Detailed characterization of the catalyst revealed that Pd(0) and Pd(II) species co-exist and were embedded in the matrix of the porous carbon (CMK-3). The as-prepared catalyst has shown high activity toward Suzuki reactions. Importantly, if the reaction mixture was homogenized by two minutes of ultrasonication rather than magnetic stirring before heating, the resistance to mass transfer in the pore channels was significantly reduced. As a result, the reactions proceeded more rapidly and a four-fold increase in the turnover frequency (TOF) could be obtained. When the ultrasonication was employed throughout the entire reaction process, the conversion could also exceed 90% even without the protection of inert gas, and although the reaction temperature was lowered to 30 °C. This work provides a method for fabricating highly active porous carbon encapsulated Pd catalysts for Suzuki reactions and proves that the problem of mass transfer in porous catalysts can be conveniently resolved by ultrasonication without any chemical modification being necessary.[Figure not available: see fulltext.] © 2014 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

Selective visuo-haptic rendering of heterogeneous objects in 'parallel universes'

 Haptic rendering of complex models is usually prohibitive due to its much higher update rate requirement compared to visual rendering. Previous works have tried to solve this issue by introducing local simulation or multi-rate simulation for the two pipelines. Although these works have improved the capacity of haptic rendering pipeline, they did not take into consideration the situation of heterogeneous objects in one scenario, where rigid objects and deformable objects coexist in one scenario and close to each other. In this paper, we propose a novel idea to support interactive visuo-haptic rendering of complex heterogeneous models. The idea incorporates different collision detection and response algorithms and have them seamlessly switched on and off on the fly, as the HIP travels in the scenario. The selection of rendered models is based on the hypothesis of “parallel universes”, where the transition of rendering one group of models to another is totally transparent to users. To facilitate this idea, we proposed a procedure to convert the traditional single universe scenario into a “multiverse” scenario, where the original models are grouped and split into each parallel universe, depending on the scenario rendering requirement rather than just locality. We also proposed to add simplified visual objects as background avatars in each parallel universe to visually maintain the original scenario while not overly increase the scenario complexity. We tested the proposed idea in a haptically-enabled needle thoracostomy training environment and the result demonstrates that our idea is able to substantially accelerate visuo-haptic rendering with complex heterogeneous scenario objects.

Infrastructure: accelerating Brazil’s growth

O Brasil se consolida como uma das maiores economias do mundo e se transformou em um país majoritariamente urbano. Acompanhando esse movimento, enormes investimentos foram feitos em infraestrutura nos últimos anos, o que vem se intensificando também em função dos grandes eventos, como a Copa 2014 e as Olimpíadas 2016. Esta edição do “Cadernos FGV Projetos”, publicada por ocasião do III Brazil Infrastructure Investment Forum, nos Estados Unidos, e dedicada ao tema Infraestrutura, traz algumas das experiências bem-sucedidas que vêm contribuindo para a modernização do país. De saneamento à construção civil, passando por transporte, telecomunicações, logística, investimentos, modelos de gestão e contratação, até os desafios de cidades e municípios e as principais necessidades do setor, diversos temas foram abordados. A publicação será lançada em inglês durante o seminário e posteriormente em português.

Casimir energy density in closed hyperbolic universes

The original Casimir effect results from the difference in the vacuum energies of the electromagnetic field, between that in a region of space with boundary conditions and that in the same region without boundary conditions. In this paper we develop the theory of a similar situation, involving a scalar field in spacetimes with closed spatial sections of negative curvature.

Casimir energy in multiply connected static hyperbolic universes

We generalize a previously obtained result for the case of a few other static hyperbolic universes with manifolds of nontrivial topology as spatial sections.

The energy of Bianchi type I and II universes in teleparallel gravity

For certain models, the energy of the universe, which includes the energy of both matter and the gravitational fields, is obtained by using the quasi-local energy-momentum in teleparallel gravity. It is shown that, in the case of the Bianchi type I and II universes, not only the total energy but also the quasi-local energy-momentum for any region vanishes independently of the three dimensionless coupling constants of teleparallel gravity.

Accelerating solutions of perfect fluid hydrodynamics for initial energy density and life-time measurements in heavy ion collisions

A new class of accelerating, exact, explicit and simple solutions of relativistic hydrodynamics is presented. Since these new solutions yield a finite rapidity distribution, they lead to an advanced estimate of the initial energy density and life-time of high energy heavy ion collisions. Accelerating solutions are also given for spherical expansions in arbitrary number of spatial dimensions.