This paper presents the design and evaluation of Pastry, a scalable, distributed object location and routing substrate for wide-area peer-to-peer ap- plications. Pastry performs application-level routing and object location in a po- tentially very large overlay network of nodes connected via the Internet. It can be used to support a variety of peer-to-peer applications, including global data storage, data sharing, group communication and naming. Each node in the Pastry network has a unique identifier (nodeId). When presented with a message and a key, a Pastry node efficiently routes the message to the node with a nodeId that is numerically closest to the key, among all currently live Pastry nodes. Each Pastry node keeps track of its immediate neighbors in the nodeId space, and notifies applications of new node arrivals, node failures and recoveries. Pastry takes into account network locality; it seeks to minimize the distance messages travel, according to a to scalar proximity metric like the number of IP routing hops. Pastry is completely decentralized, scalable, and self-organizing; it automatically adapts to the arrival, departure and failure of nodes. Experimental results obtained with a prototype implementation on an emulated network of up to 100,000 nodes confirm Pastry's scalability and efficiency, its ability to self-organize and adapt to node failures, and its good network locality properties.

/pdf/pastry-scalable-decentralized-object-location-and-routing-1u2equbbbp.pdf

Pastry: Scalable, Decentralized Object Location, and Routing for Large-Scale Peer-to-Peer Systems

The surface science of titanium dioxide

Satisfiability Modulo Theories (SMT) problem is a decision problem for logical first order formulas with respect to combinations of background theories such as: arithmetic, bit-vectors, arrays, and uninterpreted functions. Z3 is a new and efficient SMT Solver freely available from Microsoft Research. It is used in various software verification and analysis applications.

https://link.springer.com/content/pdf/10.1007%2F978-3-540-78800-3_24.pdf

Z3: an efficient SMT solver

Secret History: Return of the Black Death Channel 4, 7-8pm In 1348 the Black Death swept through London, killing people within days of the appearance of their first symptoms. Exactly how many died, and why, has long been a mystery. This Secret History documentary follows experts as they pick through the evidence and reveal why the plague killed on such a scale. And they ask, what might be coming next?

Medscape

MapReduce and its variants have been highly successful in implementing large-scale data-intensive applications on commodity clusters. However, most of these systems are built around an acyclic data flow model that is not suitable for other popular applications. This paper focuses on one such class of applications: those that reuse a working set of data across multiple parallel operations. This includes many iterative machine learning algorithms, as well as interactive data analysis tools. We propose a new framework called Spark that supports these applications while retaining the scalability and fault tolerance of MapReduce. To achieve these goals, Spark introduces an abstraction called resilient distributed datasets (RDDs). An RDD is a read-only collection of objects partitioned across a set of machines that can be rebuilt if a partition is lost. Spark can outperform Hadoop by 10x in iterative machine learning jobs, and can be used to interactively query a 39 GB dataset with sub-second response time.

/pdf/spark-cluster-computing-with-working-sets-2mqxkxxuqt.pdf

Spark: cluster computing with working sets

A containment system may include generating and/or sending an alert as the basis for safely sharing knowledge about detected worms. An alert may contain information that proves that a given program has a vulnerability. The alert may be self-certifying such that its authenticity may be independently verified by a computing system.

Self-certifying alert

Biosynthesis of gold nanoparticles by extracellular molecules produced by the phytopathogenic fungus Botrytis cinerea

Photoelectron spectra of cold Tin− anion clusters for n=1–130 were investigated at four detachment photon energies: 532, 355, 266, and 193 nm. Improved spectral resolution provides well-resolved electronic structures of the clusters, and the spectral evolution as a function of cluster size was probed systematically. Narrow and well-resolved spectral features were observed at n=13, 19, and 55, consistent with the high symmetry icosahedral structures proposed for these clusters. The measured electron affinities as a function of size in the studied size range do not extrapolate to the bulk work function, indicating that Ti clusters with n=130 may not assume the bulk structure.

Photoelectron Spectroscopy of Ti-n(-)Clusters (n=1-130)

The thermal and photon‐induced chemistry of SO2 on Ag(111) has been studied using temperature programmed desorption (TPD), Auger electron spectroscopy (AES), and work function change (ΔΦ). SO2 adsorbs reversibly on Ag(111) and desorbs in peaks at 180 and 130 K for monolayer and multilayer, respectively. The work function increases to 0.33 eV upon saturation of the chemisorbed monolayer (ML), but drops to 0.20 eV for a physisorbed multilayer. UV photons (250–542 nm) induce desorption, but not decomposition, of chemisorbed SO2. The photodesorption rate is first order in the photon flux, increases linearly with coverage up to 1 ML, but decreases sharply at higher coverages. For coverages up to 1 ML, the photodesorption cross section is (2.8±0.2)×10−20 cm2 at (313±10) nm. The wavelength dependence is consistent with substrate, including bulk plasmon, excitation. Photodesorption mechanisms involving hot electron and hole attachment processes, only in the first monolayer, are discussed.

Photochemistry of SO2 on Ag(111)

A molecular thermodynamics approach has been developed in order to describe the adsorption of fluids onto solid surfaces based on the use of discrete-potential fluid models. Using perturbation theories for fluids such as the Statistical Associating Fluid Theory (SAFT) and the Discrete Potential Theory (DPT), in combination with molecular simulation, we have formulated a two-dimensional approach to describe systems of interest for the oil industry, such as adsorption isotherms of carbon dioxide and asphaltenes.

/pdf/molecular-thermodynamics-of-adsorption-using-discrete-3uqem1sdq2.pdf

Miguel Castro

Papers

Self-certifying alert

Biosynthesis of gold nanoparticles by extracellular molecules produced by the phytopathogenic fungus Botrytis cinerea

Photoelectron Spectroscopy of Ti-n(-)Clusters (n=1-130)

Photochemistry of SO2 on Ag(111)

Molecular Thermodynamics of Adsorption using Discrete-Potential Systems