Papers.

Dynamics and diversity of online community activities

Web sites where users create and rate content as well as form networks with other users display long-tailed distributions of user activity. Using data from one such community site, Essembly, we propose and evaluate mechanisms for these distributions that rely only on information actually available to users. For Essembly, we describe the scale-free degree distribution of the social network as a result of users' shared interests, manifested by their content rating activity. We find the long tails in network properties arise from user activity rates that are broadly distributed, as well as the extensive variability in the time users devote to the site.

Translational Bioinformatics: Coming of Age

Planning Time-Minimal Safe Paths Amidst Unpredictably Moving Obstacles

In this paper we discuss the problem of planning safe paths amidst unpredictably moving obstacles in the plane. Given the initial positions and the maximum speeds of the moving obstacles, which we assume are disk-shaped, the regions that are possibly not collision-free are disks that grow over time. We present an approach to compute the time-minimal path between two points in the plane that avoids these growing disks. The generated paths are thus guaranteed to be collision-free with respect to the moving obstacles while being executed. We present an algorithm that runs in O (n 3 log n) time (n being the number of obstacles) for the case where the moving obstacles have the same maximum speed, and a fast implementation for the general case that is capable of planning paths amidst many growing disks within milliseconds.

Planning High-quality Paths and Corridors Amidst Obstacles

The motion-planning problem, involving the computation of a colli sion-free path for a moving entity amidst obstacles, is a central prob lem in fields such robotics and game design. In this paper we study the problem of planning high-quality paths. A high-quality path should have some desirable properties: it should be short, avoiding long detours, and at the same time it should stay at a safe distance from the obstacles, namely it should have clearance. We suggest a quality measure for paths, which balances between the above criteria of minimizing the path length while maximizing its clearance. We analyze the properties of optimal paths according to our measure, and devise an approximation algorithm to compute near-optimal paths amidst polygonal obstacles in the plane. We also apply our quality measure to corridors. Instead of planning a one-dimensional motion path for a moving entity, it is often more convenient to let the entity move in a corridor, where the exact motion path is determined by a local planner. We show that planning an optimal corridor is equivalent to planning an optimal path with bounded clearance.

Predicting the popularity of online content

Early patterns of Digg diggs and YouTube views reflect long-term user interest.

From hits to niches?

SNAKDD 2008 social network mining and analysis postworkshop report

Crowdsourcing for relevance evaluation

If you like the beatles you might like...

Leveraging social context for searching social media

Improved query difficulty prediction for the web

Link Privacy in Social Networks

Real-World Concurrency

Software practitioners today could be forgiven if recent microprocessor developments have given them some trepidation about the future of software. While Moore’s law continues to hold (that is, transistor density continues to double roughly every 18 months), as a result of both intractable physical limitations and practical engineering considerations, that increasing density is no longer being spent on boosting clock rate. Instead, it is being used to put multiple CPU cores on a single CPU die. From the software perspective, this is not a revolutionary shift, but rather an evolutionary one: multicore CPUs are not the birthing of a new paradigm, but rather the progression of an old one (multiprocessing) into more widespread deployment.

A new approach to evaluating novel recommendations

PFP: Parallel FP-Growth for Query Recommendation

A questionnaire-based study on delayed reciprocity in a P2P-tv system

Polymorphic embedding of dsls

The influential pure embedding methodology of embedding domain-specific languages (DSLs) as libraries into a general-purpose host language forces the DSL designer to commit to a single semantics. This precludes the subsequent addition of compilation, optimization or domain-specific analyses. We propose polymorphic embedding of DSLs, where many different interpretations of a DSL can be provided as reusable components, and show how polymorphic embedding can be realized in the programming language Scala. With polymorphic embedding, the static type-safety, modularity, composability and rapid prototyping of pure embedding are reconciled with the flexibility attainable by external toolchains.

Generics of a higher kind

With Java 5 and C# 2.0, first-order parametric polymorphism was introduced in mainstream object-oriented programming languages under the name of generics. Although the first-order variant of generics is very useful, it also imposes some restrictions: it is possible to abstract over a type, but the resulting type constructor cannot be abstracted over. This can lead to code duplication. We removed this restriction in Scala, by allowing type constructors as type parameters and abstract type members. This paper presents the design and implementation of the resulting type constructor polymorphism. Furthermore, we study how this feature interacts with existing object-oriented constructs, and show how it makes the language more expressive.

From OCaml to Javascript at Skydeck

Design trade-offs for search engine caching

Community evolution in dynamic multi-mode networks

Extracting shared subspace for multi-label classification

Real-world concurrency

What does the proliferation of concurrency mean for the software you develop?

ORM in Dynamic Languages

A major component of most enterprise applications is the code that transfers objects in and out of a relational database. The easiest solution is often to use an ORM (object-relational mapping) framework, which allows the developer to declaratively define the mapping between the object model and database schema and express database-access operations in terms of objects. This high-level approach significantly reduces the amount of database-access code that needs to be written and boosts developer productivity.

Towards acceleration of fault simulation using graphics processing units

ResIn

Improving peer connectivity in wide-area overlays of virtual workstations

Knowledge and Wisdom

Diversity of online community activities

QDSL: a queuing model for systems with differential service levels

Expertise identification and visualization from CVS

Genealogical trees on the web

Query-sets

Improving FPGA routability using network coding

Managing data quality in a terabyte-scale sensor archive.

Friends and foes: ideological social networking

IWannaBit!

Data challenges at Yahoo!

Data challenges at Yahoo!

SAT-based ATPG using multilevel compatible don't-cares

Interactive navigation of multiple agents in crowded environments

We present a novel approach for interactive navigation and planning of multiple agents in crowded scenes with moving obstacles. Our formulation uses a precomputed roadmap that provides macroscopic, global connectivity for wayfinding and combines it with fast and localized navigation for each agent. At runtime, each agent senses the environment independently and computes a collision-free path based on an extended "Velocity Obstacles" concept. Furthermore, our algorithm ensures that each agent exhibits no oscillatory behaviors. We have tested the performance of our algorithm in several challenging scenarios with a high density of virtual agents. In practice, the algorithm performance scales almost linearly with the number of agents and can run at interactive rates on multi-core processors.

Identifying the influential bloggers in a community

Securing web applications with static and dynamic information flow tracking

Link analysis for Web spam detection

Topic taxonomy adaptation for group profiling

Searching for gluinos at the Tevatron and beyond

Eternal Inflation (book)

Geometro-thermodynamics of tidal charged black holes

Tidal charged spherically symmetric vacuum brane black holes are characterized by their mass m and tidal charge q, an imprint of the 5-dimensional Weyl curvature. For q>0 they are formally identical to the Reissner-Nordström black hole of general relativity. We study the thermodynamics and thermodynamic geometries of tidal charged black holes and discuss similarities and differences as compared to the Reissner-Nordström black hole. As a similarity, we show that (for q>0) the heat capacity of the tidal charged black hole diverges on a set of measure zero of the parameter space, nevertheless both the regularity of the Ruppeiner metric and a Poincaré stability analysis shows no phase transition at those points. The thermodynamic state spaces being different indicates that the underlying statistical models could be different. We find that the q<0 parameter range, which enhances the localization of gravity on the brane, is thermodynamically preferred. Finally we constrain for the first time the possible range of the tidal charge from the thermodynamic limit on gravitational radiation efficiency at black hole mergers.

Speaker identification on the SCOTUS corpus

Gemini queue planning

The Gemini telescopes were designed to be queue scheduled and currently more than 90% of the telescope time is devoted to queue observing. In queue mode observations are done in the conditions that are appropriate for them and it is easier to accommodate programs that require flexible scheduling such as Target of Opportunity observations of gamma ray bursts. This presentation outlines the Gemini queue planning process and gives an overview of the Gemini queue planning tool and the plans for its near-term development.