Onion under Microscope: An in-depth analysis of the Tor Web

World Wide Web - Tor is an open source software that allows accessing various kinds of resources, known as hidden services, while guaranteeing sender and receiver anonymity. Tor relies on a free,...     

Multiparty session types as coherence proofs

Acta Informatica - We propose a Curry–Howard correspondence between a language for programming multiparty sessions and a generalisation of Classical Linear Logic (CLL). In this framework,...     

On the Virtualization of CUDA Based GPU Remoting on ARM and X86 Machines in the GVirtuS Framework

The astonishing development of diverse and different hardware platforms is twofold: on one side, the challenge for the exascale performance for big data processing and management; on the other side, the mobile and embedded devices for data collection and human machine interaction. This drove to a highly hierarchical evolution of programming models. GVirtuS is the general virtualization system developed in 2009 and firstly introduced in 2010 enabling a completely transparent layer among GPUs and VMs. This paper shows the latest achievements and developments of GVirtuS, now supporting CUDA 6.5, memory management and scheduling. Thanks to the new and improved remoting capabilities, GVirtus now enables GPU sharing among physical and virtual machines based on x86 and ARM CPUs on local workstations, computing clusters and distributed cloud appliances.     

DeepProposals: Hunting Objects and Actions by Cascading Deep Convolutional Layers

In this paper, a new method for generating object and action proposals in images and videos is proposed. It builds on activations of different convolutional layers of a pretrained CNN, combining the localization accuracy of the early layers with the high informativeness (and hence recall) of the later layers. To this end, we build an inverse cascade that, going backward from the later to the earlier convolutional layers of the CNN, selects the most promising locations and refines them in a coarse-to-fine manner. The method is efficient, because (i) it re-uses the same features extracted for detection, (ii) it aggregates features using integral images, and (iii) it avoids a dense evaluation of the proposals thanks to the use of the inverse coarse-to-fine cascade. The method is also accurate. We show that DeepProposals outperform most of the previous object proposal and action proposal approaches and, when plugged into a CNN-based object detector, produce state-of-the-art detection performance.     

Effect of vacuum venting and mold wettability on the replication of micro-structured surfaces

Micro injection molding enables the manufacture of micro-scale features with good accuracy at high production rates. However, the replication of complex micro and nano features is still challenging hindering the development of new functional surface topographies. The marked thermal gradient between injected polymer and mold surface and the reduced dimensions promote a rapid drop of melt temperature that causes the incomplete filling of the micro features. This study aims to investigate the combined effects of vacuum venting and mold wettability on the replication of micro-structured surfaces. A low-viscosity polystyrene and a cyclic olefin copolymer were selected and their wetting properties were evaluated. The results showed that a polymer with high wetting properties and an elevated viscosity dependence on temperature improves the replication of the micro features. Moreover, high interfacial effects can be exploited to significantly enhance the filling ratio when applying vacuum venting.

     

An Efficient Method to Correct Under-Dispersion in Ensemble Streamflow Prediction of Inflow Volumes for Reservoir Optimization

Ensemble streamflow prediction (ESP) has been widely used to gain insight on possible future inflows to hydropower reservoirs. However underestimation of climate, model structure and initial condition uncertainty often leads to under-dispersed ESP forecasts. In this paper, we present a novel approach called “Hindcast-mode Uncertainty Estimation” (HUE) to efficiently add variability in ESP forecasts to reduce their under-dispersion. The method was tested on a Canadian catchment used by Rio Tinto – Aluminium division to produce hydropower for their aluminium smelting plants. This project was focused on correcting long-term predictions of freshet runoff volumes to optimize drawdown volumes, with up to 6 months of lead time. It was found that by adding an error term to the hydrological model’s snow water equivalent (SWE) state variable at the time of forecast in hindcasting mode, the resulting simulation could be forced to perfectly reproduce the freshet runoff volume. This error term was computed for all years on record which enabled modeling of the error’s distribution. This distribution can then be sampled from to add noise to the model’s SWE at the start of a new ESP forecast. Results show that the current winter ESP forecasts are strongly under-dispersed for the freshet runoff volume estimation and that the proposed method is able to widen the ESPs to correct the under-dispersion problem. This was validated by using Talagrand diagrams which shifted from a U-shape (prior to HUE) to a uniform distribution (with HUE). The project objectives of correcting the ESP forecast’s under-dispersion in spring runoff estimations was thus attained with minimal effort, bypassing the need to perform more complex ensemble data assimilation techniques.     

Activity of a β‐nucleating agent for isotactic polypropylene and its influence on polymorphic transitions

The influence of a nonpigmenting β‐nucleating additive in the crystallization of isotactic polypropylene (iPP) is investigated by differential scanning calorimetry and X‐ray diffraction. It is found that this additive induces the formation of a very high level of the trigonal modification of iPP. The crystallization and melting behavior of the nucleated systems are studied as a function of the cooling and heating rates and the control of the final temperature during the cooling process. The nucleating agent exerts an important effect on the crystallization temperatures and the polymorphic transitions of iPP, delaying the β–α recrystallization process through an increase in the stability of the trigonal crystals. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 531–539, 2002     

Electrostatic effects on the thermodynamics of protonation of reduced plastocyanin

The L12E, L12K, Q88E, and Q88K variants of spinach plastocyanin have been electrochemically investigated. The effects of insertion of net charges near the metal site on the thermodynamics of protonation and detachment from the copper(I) ion of the His87 ligand have been evaluated. The mutation-induced changes in transition enthalpy cannot be explained by electrostatic considerations. The existence of enthalpy/entropy (H/S) compensation within the protein series indicates that solvent-reorganization effects control the differences in transition thermodynamics. Once these compensating contributions are factorized out, the resulting modest differences in transition enthalpies turn out to be those that can be expected on purely electrostatic grounds. Therefore, this work shows that the acid transition in cupredoxins involves a reorganization of the H-bonding network within the hydration sphere of the molecule in the proximity of the metal center that dominates the observed transition thermodynamics and masks the differences that are due to protein-based effects.     

Aqueous two‐phase systems for the recovery of a recombinant viral coat protein from Escherichia coli

In this study the use of an aqueous two‐phase system (ATPS) following the direct chemical extraction of a recombinant viral coat protein, from the cytoplasm of Escherichia coli, is evaluated. The driving force is the need to establish an economically‐viable process for the manufacture of a vaccine against human papilloma infection. The partition behaviour of recombinant L1 protein, the major structural protein of the virus, and DNA was investigated in a polyethylene glycol (PEG)–phosphate system. An evaluation of system parameters including PEG molecular mass and the concentrations of PEG and phosphate was conducted, to estimate conditions under which the L1 protein and DNA partition to opposite phases. ATPS extraction comprising a volume ratio of 1.00, PEG 1000 (18.0%(w/w)) and phosphate (15.0%(w/w)) provided the conditions for accumulation of DNA into the bottom phase and concentration of L1 protein into the opposite phase (ie partition coefficient of DNA; ln K_DNA < 0.0 and partition coefficient of L1; ln K_L1 > 2.5). The findings reported here demonstrate the potential of ATPS to recover recombinant protein released from E coli by direct chemical extraction. © 2002 Society of Chemical Industry     

Ion Irradiation of Preceramic Polymer Thin Films

Thin films of two preceramic polymers, namely polycarbosilane (PCS) and a silicone resin (SR350), were deposited on Si substrates. Instead of employing conventional annealing at high temperatures in an inert atmosphere, ion irradiation was used to achieve the polymer-to-ceramic conversion. A detailed investigation of the changes in the composition, chemical structure, and hardness was performed by means of ion beam analysis (Rutherford backscattering spectrometry, nuclear reaction analysis, and elastic recoil detection analysis), FTIR, Raman and nanoindentation, respectively. This processing method yielded amorphous Si-C and Si-O-C coatings possessing high hardness and density. Compared to films heat-treated under vacuum at 1000°C, ion-irradiated ones exhibited a similar hydrogen content, a lower oxygen contamination, and a higher carbon content. Annealing at 1000°C of previously irradiated films resulted in coatings still possessing a high carbon content and a high hardness.