bluuebunny/crossref_metadata_2025 huggingface dataset:
COLLECTIVE EXCITATIONS IN SUPERCONDUCTORS AND SEMICONDUCTORS IN THE PRESENCE OF A CONDENSED PHASE
Authors: KOINOV ZLATKO
Published: February 2011

We first study the spectrum of the excitonic polaritons in semiconductors in the presence of a condensed phase. With the help of the Hubbard-Stratonovich transformation we propose an exact mapping of the extended Hubbard model onto an excitonic-polariton model describing the light propagation in semiconductors. This approach allows us to derive exact formulas for spin-spin and charge-charge correlation functions for spin-triplet superconductivity.
INTERMITTENCY NEAR A CODIMENSION THREE STEADY-STATE BIFURCATION
Authors: BLOMGREN PETER , MARTINEZ JOAN MANUEL , PALACIOS ANTONIO
Published: February 2011

We study the existence and stability of heteroclinic connections near "hopping" cellular flame patterns. These are dynamic patterns in which individual cells make sequential, and abrupt, changes in their angular positions while they rotate nonuniformly about the center of a circular domain. Normal form analysis and experimental works have shown that these patterns are associated with a homoclinic cycle connecting group related equilibria. In fact, they emerge through a codimension three steady-state bifurcation of three modes with wave numbers in a 2:3:4 ratio. While cycles are known to exist in the mode-2 and mode-4 interactions, here we show that mode-3 destabilizes the connection so that only remnants, i.e. intermittent flame patterns of the cycles can be observed.
ASPECT-ORIENTED SPECIFICATION: A CASE STUDY IN SPACE DOMAIN
Authors: AGOSTINHO SÉRGIO , MOREIRA ANA , MARQUES ANDRÉ , ARAÚJO JOÃO , FERREIRA RICARDO , RAMINHOS RICARDO , RIBEIRO RITA , BRITO ISABEL , CHEVALLEY PHILIPPE
Published: February 2011

Aspect-oriented software development claims to improve several software engineering principles, such as modularization, abstraction and composition. The Aspect for the Space Domain project (ASSD) developed a metadata-driven approach for aspect-oriented requirements analysis. The main objectives of the ASSD project, funded by the European Space Agency , were to study the applicability and usefulness of aspect-orientation for the space domain (ground segment software projects in particular), focusing on the early stages of the software development life cycle. Therefore, this paper describes a rigorous representation for requirements analysis concepts, refines an approach for handling early aspects, and proposes a client/server architecture based on a metadata repository. The ASSD approach has been validated with two space domain case studies.
EXPLOITING A GENERIC APPROACH TO CONSTRUCT COMPONENT-BASED SYSTEMS SOFTWARE IN LINUX ENVIRONMENTS
Authors: UEYAMA JÓ , MADEIRA EDMUNDO R. M. , TAIANI FRANCOIS , CAMARGO RAPHAEL Y. , GRACE PAUL , COULSON GEOFF
Published: February 2011

Component-based software engineering has recently emerged as a promising solution to the development of system-level software. Unfortunately, current approaches are limited to specific platforms and domains. This lack of generality is particularly problematic as it prevents knowledge sharing and generally drives development costs up. In the past, we have developed a generic approach to component-based software engineering for system-level software called OpenCom. In this paper, we present OpenComL an instantiation of OpenCom to Linux environments and show how it can be profiled to meet a range of system-level software in Linux environments. For this, we demonstrate its application to constructing a programmable router platform and a middleware for parallel environments.
OBSERVATIONAL CONSTRAINTS ON PHANTOM CROSSING DGP GRAVITY
Authors: HIRANO KOICHI , KOMIYA ZEN
Published: February 2011

We study the observational constraints on the Phantom Crossing DGP model. We demonstrate that the crossing of the phantom divide does not occur within the framework of the original Dvali–Gabadadze–Porrati (DGP) model or the DGP model developed by Dvali and Turner. By extending their model in the framework of an extra dimension scenario, we study a model that realizes crossing of the phantom divide. We investigate the cosmological constraints obtained from the recent observational data of Type Ia supernovae, cosmic microwave background anisotropies, and baryon acoustic oscillations. The best-fit values of the parameters with 1σ (68%) errors for the Phantom Crossing DGP model are [Formula: see text]. We find that the Phantom Crossing DGP model is more compatible with the observations than the original DGP model or the DGP model developed by Dvali and Turner. Our model can realize late-time acceleration of the universe, similar to that of ΛCDM model, without dark energy due to the effect of DGP gravity. In our model, the crossing of the phantom divide occurs at a redshift of z ~ 0.2.
QSAR AND PHARMACOPHORE MODELING OF 4-ARYLTHIENO [3, 2-d] PYRIMIDINE DERIVATIVES AGAINST ADENOSINE RECEPTOR OF PARKINSON'S DISEASE
Authors: AHMED SHIEK S. S. J. , AHAMEETHUNISA A. , SANTOSH WINKINS
Published: February 2011

A series of 47, 4-arylthieno[3, 2-d] pyrimidine derivatives was subjected to quantitative structure-antiparkinson activity relationships (QSAR) studies to evaluate the antagonist activity towards both adenosine A1 and adenosine A2A targets in Parkinson's drug discovery. QSAR models were derived with the aid of genetic function approximation (GFA) technique using descriptors to make connections between structural parameters and antiparkinson's activity followed by ADMET analysis and pharmacophore model generation. QSAR model was assessed using a test set of 12 compounds for A1 (r2 pred = 0.961), (q2 = 0.912) and 12 compounds for A2a (r2 pred = 0.914), (q2 = 0.781) receptor. The results revealed the significant role of DIPOLE MAG, CHI-V-3-P, WIENER, AREA, SC-2 and PHI-MAG descriptors in the antiparkinson activity of the studied compounds against adenosine A1 and adenosine A2A receptors. Subsequent, ADMET analysis shows 28 compounds can be the better candidates of drug and execution of pharmacophore model, explores the hydrogen bond donor, aromatic ring and hydrophobic groups are the key structural features for the antagonist activity.
HEATS OF FORMATION FOR BORON COMPOUNDS BASED ON QUANTUM CHEMICAL CALCULATIONS
Authors: ZHANG JIAHENG , WEI SHIQIAN , MAO CHAOZHU , CHEN LIANG , GAO HAIXIANG , ZHOU WENFENG , ZHOU ZHIQIANG
Published: February 2011

We have calculated the heats of formation at 298.15 K of series of boron compounds including H , N , O , F , Cl atoms using the atomization enthalpies analysis based on eleven quantum chemical calculations. The majority of calculated values are in excellent agreement with available experiment values and Gaussian-n methods perform more accurate evaluations than other approaches. As with the existing literature, the following calculations of the heats of formation of borides containing light atoms are recommended as accurate values: ΔfHG2,298 (BH) = 442.731 kJ·mol-1, ΔfHG2,298 (BF3) = -1135.749 kJ·mol-1, the deviations are respectively 0.031 kJ·mol-1 and 0.251 kJ·mol-1. Furthermore, ab initio calculations of heats of formation of chlorinated boron compounds also show good accuracy and comparisons with previous thermodynamics data are made.
SOLVENT EFFECTS ON THE KETO-ENOL TAUTOMERIC EQUILIBRIUM OF TETRONIC AND ETHYL ACETOACETATE CARBON ACIDS: A THEORETICAL STUDY
Authors: CHARIF I. E. , MEKELLECHE S. M. , VILLEMIN D.
Published: February 2011

The solvent effects on the keto-enol tautomeric equilibriums of ethyl acetoacetate (EAA) and tetronic acid (TA) are theoretically investigated. The present study shows that the most stable keto tautomer of EAA corresponds to the trans diketo, E, Z form; while the most stable enol tautomer corresponds to the structure in which the enolization takes place at the carbonyl group. Our calculations also put in evidence that the keto tautomer of TA prefers the trans diketo, E, E form, while the most stable enol tautomer corresponds to the structure in which the enolization takes place at the carbonyl group. The calculated free energies indicate that, in polar solvents, the keto-enol equilibrium of EAA is shifted towards the keto tautomer, whereas the keto-enol equilibrium of TA is shifted toward the enol tautomer. The trends of the change of equilibrium constants with respect to the change of solvent polarity are well reproduced by both B3LYP and MP2 calculations. The present study shows that the enthalpic term is predominant in the determination of the calculated equilibrium constants and the entropic effect on the calculated Gibbs free energies is found to be very small and has little influence on the studied keto-enol tautomeric equilibriums.
DOCKING OF RALTEGRAVIR TO HIV-1 INTEGRASE STRUCTURE ENSEMBLE
Authors: WEI CAIYI , LIU ZEYU , ZHANG DAWEI , MEI YE
Published: February 2011

Docking of the drug raltegravir to HIV-1 integrase (IN) was performed based on the established Relaxed Complex Scheme (RCS) method which accounts for the flexibility of both receptor and ligand in molecular docking. Two representative butterfly-like structures of raltegravir were identified and both of them mimicked the binding mode of 5CITEP with similar ligand-receptor interactions. Furthermore, the results that raltegravir interacted with magnesium by intermediate water molecules indicate the importance of water molecules at the binding site which has always been ignored in the docking studies of IN inhibitors. Taking these water molecules into consideration gives more insight into the design and development of the second generation IN inhibitors.
THEORETICAL STUDY OF STEREO-DYNAMICS FOR THE REACTION C(3P) + CH(2II) → C2 + H ON THE THREE LOWEST POTENTIAL ENERGY SURFACES
Authors: LIU ZUOYE , HU BITAO
Published: February 2011

Based on the global three-dimensional adiabatic potential surfaces (PESs) 12 A ′, 22 A ′, 12 A ″ [Boggio-Pasqua et al., Phys Chem Chem Phys2:1693, 2000], the stereo-dynamics of the reaction C + CH → C 2 + H has been investigated by using the quasi-classical trajectories (QCT) method. The four polarization-dependent differential cross sections (PDDCSs) and the angular distributions of P(θr), P(ϕr), P(θr, ϕr) have been calculated at the collision energy 0.1 eV on the three PESs, respectively. The calculated results indicate that the distribution of the product C2 is backward-forward scattering on the 12 A ′ and 12 A ″ PESs and backward scattering on the 22 A ′ PES. The product rotational angular momentum is strongly aligned along the perpendicular direction to the reagent relative velocity k on the three PESs. The orientation of the product C 2 rotational angular momentum tends to point to the positive direction of the y-axis on the 12 A ′ PES but the negative direction on the 22 A ′ and 12 A ″ PESs.
AN ASYMMETRIC ADAPTIVE CLASSIFICATION METHOD
Authors: WU LIANWEN , CHENG QIANSHENG
Published: February 2011

There should be different requirements for False Reject rate and False Accept rate in classification applications, and classifier learning should use an asymmetric factor to balance between False Reject rate and False Accept rate. A novel AdaBoost algorithm was developed with the asymmetric weight. Moreover we provide the theoretical analysis of its performance and derive the upper bound of the classification error.
ON OPTIMAL WAVELET BASES FOR THE REALIZATION OF MICROCANONICAL CASCADE PROCESSES
Authors: PONT ORIOL , TURIEL ANTONIO , PÉREZ-VICENTE CONRAD J.
Published: February 2011

Multiplicative cascades are often used to represent the structure of turbulence. Under the action of a multiplicative cascade, the relevant variables of the system can be understood as the result of a successive transfer of information in cascade from large to small scales. However, to make this cascade transfer explicit (i.e. being able to decompose each variable as the product of larger scale contributions) is only achieved when signals are represented in an optimal wavelet basis. Finding such a basis is a data-demanding, highly-complex task. In this paper, we propose a formalism that allows to find the optimal wavelet of a signal in an efficient, little data-demanding way. We confirm the appropriateness of this approach by analyzing the results on synthetic signals constructed with prescribed optimal bases. We show the validity of our approach constrained to given families of wavelets, though it can be generalized for a continuous unconstrained search scheme.
CURVELET-WAVELET REGULARIZED SPLIT BREGMAN ITERATION FOR COMPRESSED SENSING
Authors: PLONKA GERLIND , MA JIANWEI
Published: February 2011

Compressed sensing is a new concept in signal processing. Assuming that a signal can be represented or approximated by only a few suitably chosen terms in a frame expansion, compressed sensing allows one to recover this signal from much fewer samples than the Shannon–Nyquist theory requires. Many images can be sparsely approximated in expansions of suitable frames as wavelets, curvelets, wave atoms and others. Generally, wavelets represent point-like features while curvelets represent line-like features well. For a suitable recovery of images, we propose models that contain weighted sparsity constraints in two different frames. Given the incomplete measurements f = Φu + ϵ with the measurement matrix Φ ∈ ℝK × N, K ≪ N, we consider a jointly sparsity-constrained optimization problem of the form [Formula: see text]. Here Ψcand Ψware the transform matrices corresponding to the two frames, and the diagonal matrices Λc, Λwcontain the weights for the frame coefficients. We present efficient iteration methods to solve the optimization problem, based on Alternating Split Bregman algorithms. The convergence of the proposed iteration schemes will be proved by showing that they can be understood as special cases of the Douglas–Rachford Split algorithm. Numerical experiments for compressed sensing-based Fourier-domain random imaging show good performances of the proposed curvelet-wavelet regularized split Bregman (CWSpB) methods, where we particularly use a combination of wavelet and curvelet coefficients as sparsity constraints.
WILSON SYSTEM FOR TRIPLE REDUNDANCY
Authors: WOJDYŁŁO PIOTR
Published: February 2011

A Wilson orthonormal basis was constructed in 1991 by Daubechies, Jaffard and Journé from Gabor tight frame elements, when the redundancy of the Gabor system is 2. In 1994, Auscher gave a characterization of the atoms for which the Wilson system is an orthonormal basis. Afterwards, Gröchenig posed a question whether the construction of an orthonormal Wilson basis is possible for a Gabor tight frame of redundancy 3. We give a partial positive answer to this question constructing in this case a Wilson system being a tight frame with bound 1.
ENTROPIC INTERPRETATION OF EMPIRICAL MODE DECOMPOSITION AND ITS APPLICATIONS IN SIGNAL PROCESSING
Authors: TSENG CHIH-YUAN , LEE HC
Published: February 2011

The Hilbert-Huang transform (HHT) method, which is designed to analyze nonstationary and nonlinear time-dependent data, is attracting lots of attention. The HHT first applies the empirical mode decomposition (EMD) to decompose data into intrinsic mode functions (IMF). The Hilbert transform then is applied to the IMFs to reveal its instantaneous frequency spectrum. However, because the EMD lacks analytical interpretation, the meaning of IMFs is unclear. This work proposes an entropic analysis strategy to provide an information-based interpretation. Based on this strategy, three applications in data analysis are demonstrated: (1) studies of characteristic of white noise, (2) determination of minimum sampling rates to generate sufficient numbers of realizations, and (3) a low pass noise filter design.
NORTH ATLANTIC OCEAN BASIN TROPICAL CYCLONE ACTIVITY AS RELATED TO CLIMATE FACTORS FOR THE 2010 HURRICANE SEASON
Authors: YAN T. , PIETRAFESA L. J. , DICKEY D. A. , BAO S. , HUANG N. E. , WU Z.
Published: February 2011

Atmospheric and oceanic climate factors and conditions play a crucial role in modulating seasonal/annual tropical cyclone activity in the North Atlantic Ocean Basin. In the following, correlations between North Atlantic tropical cyclone activity including frequency of occurrence and pathways are explored, with special emphasis on hurricanes. The value of two-dimensional and three-dimensional data sets representing climate patterns is investigated. Finally, the diagnostic study of historical tropical cyclone and hurricane temporal and spatial variability and relationships to climate factors lead to a statistical prognostic forecast, made in April, 2010, of the 2010 tropical cyclone and hurricane season. This forecast is tested both retrospectively and presently and is shown to be quite accurate. Knowing the probability of the frequency of occurrence, i.e. the numbers of named storms to form in general and the number of hurricanes (NHs) that are likely to form, is important for many societal sectors. However, the reliable forecasts of probable pathways of predicted events, specifically the likely NH land falls along the coastlines of the United States, should have great potential value to emergency planners, the insurance industry, and the public. The forecast provided in this study makes such a prognostication. As the 2010 hurricane season has progressed, an update of the goodness of the forecast is shown to be quite accurate in numbers of named events, hurricanes, major hurricanes (MHs), and landfalls. The mathematical and statistical methodology used in this study, which could be coupled to next generation "empirical modal decomposition," suggests that this may signal a new era in the future of tropical cyclone forecasting, including the reliable prognostication of numbers of events, intensities of events, and the pathways of those events. The ability to reliably predict the probability and location of land falls of these destructive events would be very powerful indeed.
CONSTRUCTING CROSSOVER-FRACTALS USING INTRINSIC MODE FUNCTIONS
Authors: LIAW SY-SANG , CHIU FENG-YUAN
Published: February 2011

Real nonstationary time sequences are in general not monofractals. That is, they cannot be characterized by a single value of fractal dimension. It has been shown that many real-time sequences are crossover-fractals: sequences with two fractal dimensions — one for the short and the other for long ranges. Here, we use the empirical mode decomposition (EMD) to decompose monofractals into several intrinsic mode functions (IMFs) and then use partial sums of the IMFs decomposed from two monofractals to construct crossover-fractals. The scale-dependent fractal dimensions of these crossover-fractals are checked by the inverse random midpoint displacement method (IRMD).
IMAGE IMPROVEMENT IN THE WAVELET DOMAIN FOR OPTICAL COHERENCE TOMOGRAMS
Authors: WANG YINGLI , LIANG YANMEI , WANG JINGYI , ZHANG SHU
Published: February 2011

In this paper, an image processing method for improving the quality of optical coherence tomography (OCT) images is proposed. Wavelet denoising based on context modeling and contrast enhancement by means of the contrast measure in the wavelet domain is carried out on the OCT images in succession. Three parameters are selected to assess the effectiveness of the method. It is shown from the results that the proposed method can not only enhance the contrast of images, but also improve signal-to-noise ratio. Compared with two other typical algorithms, it has the best visual effect.
Hinterland-foreland zonation of the Variscan orogen in the Central Pyrenees: comparison with the northern part of the Iberian Variscan Massif
Authors: García-Sansegundo J. , Poblet J. , Alonso J. L. , Clariana P.
Published: February 2011

A new sequence of Variscan deformations is proposed for the Palaeozoic rocks of the Central Pyrenees. The non-metamorphic units include south-directed thrust systems and related folds with a poorly developed cleavage. In the metamorphic units north-verging, recumbent to inclined folds (D1), associated with a subhorizontal to south dipping cleavage, are refolded by south-verging, upright to inclined folds (D2), with a subvertical to north-dipping axial plane cleavage, and offset by south-directed thrusts approximately coeval with D2. The structural evolution of these units suggests a subdivision of the Variscan Central Pyrenees into two different regions consistent with the zones known for a long time in the core of the Ibero-Armorican or Asturian arc (northern part of the Iberian Variscan Massif). The structure of the Pyrenean non-metamorphic units has foreland affinities and is comparable to that of the Cantabrian Zone, whereas the deformation observed in the Pyrenean metamorphic units is characteristic of the hinterland and is consistent with the features of the West Asturian–Leonese Zone or Central–Iberian Zone. Since the Pyrenean non-metamorphic units are located southwards of the metamorphic ones and the Variscan thrusts are south-directed, we tentatively correlate the Variscan Pyrenees with the northern branch of the Ibero-Armorican or Asturian arc.
Multigranularity reuse of learning resources
Authors: Meyer Marek , Rensing Christoph , Steinmetz Ralf
Published: February 2011

This article investigates a scenario of reuse in which existing learning resources serve as preliminary products for the creation of new learning resources. Authors should be able to reuse learning resources and also parts of them at different levels of granularity in a modular way. The requirements of multigranularity reuse are analyzed and compared to existing solutions. A concept for modular, multigranularity reuse is presented in this article. It is also shown how this kind of reuse can be achieved in practise.
SMIL builder
Authors: Bouyakoub Samia , Belkhir Abdelkader
Published: February 2011

We present in this article a temporal SMIL editor with incremental verification capabilities, based on a formal Petri Net--based model. Our authoring tool, named SMIL Builder, allows the author to “build” his document step by step, while insuring at every stage the validity of the current state of the document. These incremental authoring and consistency checking features are based on the H-SMIL-Net model (Hierarchical SMIL Petri Net), a temporal extension of Petri Nets. Our aim is to propose an easy-to-use temporal environment which can satisfy a wide range of users; so we opted for an interface combining simplicity and ergonomics.
An empirical analysis of serendipitous media sharing among campus-wide wireless users
Authors: Chandra Surendar , Yu Xuwen
Published: February 2011

Contemporary systems use centralized as well as peer-to-peer mechanisms for the large scale distribution of media objects. In this work, we investigate a serendipitous mechanism for directly sharing media objects among a local community of wireless users. This localized sharing is attractive when wide area network connectivity is undesirable, expensive or unavailable; especially when the shared media objects are large. With some restrictions, such localized sharing of media objects is also acceptable to content owners. However, localized sharing has to contend with far fewer media providers who may also not offer the variety of objects available from wide-area services. We collected empirical data from the widely deployed Apple iTunes application for our analysis. We showed that users are already making a significant amount of media objects available for serendipitous sharing. Our analysis showed that the shared object annotations exhibited a Zipfian long tail distribution. The availability patterns of wireless iTunes users and the object annotations makes serendipitous sharing inappropriate for scenarios that require access to a specific object. Instead, mechanisms that allow the user to specify classes of interesting objects are better suited for such users. Also, given the smaller scale of these systems, serendipitous sharing can benefit from approaches that allow users to disseminate a compact representation of their shared objects. Though the wireless user availability rates was not as high as what was observed in a corporate desktop setting, a large fraction of the users showed high temporal consistency. This allows for high availability with reasonable replication during weekday daytime hours. We answer important questions regarding the viability of a campus-wide media sharing system.
A review of grid authentication and authorization technologies and support for federated access control
Authors: Jie Wei , Arshad Junaid , Sinnott Richard , Townend Paul , Lei Zhou
Published: February 2011

Grid computing facilitates resource sharing typically to support distributed virtual organizations (VO). The multi-institutional nature of a grid environment introduces challenging security issues, especially with regard to authentication and authorization. This article presents a state-of-the-art review of major grid authentication and authorization technologies. In particular we focus upon the Internet2 Shibboleth technologies and their use to support federated authentication and authorization to support interinstitutional sharing of remote grid resources that are subject to access control. We outline the architecture, features, advantages, limitations, projects, and applications of Shibboleth in a grid environment. The evidence suggests that Shibboleth meets many of the demands of the research community in accessing and using grid resources.
In the Virtual Extension
Authors: CACM Staff
Published: February 2011

To ensure the timely publication of articles,
Communications
created the Virtual Extension (VE) to expand the page limitations of the print edition by bringing readers the same high-quality articles in an online-only format. VE articles undergo the same rigorous review process as those in the print edition and are accepted for publication on merit. The following synopses are from articles now available in their entirety to ACM members via the Digital Library.
Against cyberterrorism
Authors: Conway Maura
Published: February 2011

Why cyber-based terrorist attacks are unlikely to occur.
Household demand for broadband internet service
Authors: Rosston Gregory , Savage Scott , Waldman Donald
Published: February 2011

How much are consumers willing to pay for broadband service?
Technology, conferences, and community
Authors: Grudin Jonathan
Published: February 2011

Considering the impact and implications of changes in scholarly communication.
Puzzled: Parsing partitions
Authors: Winkler Peter
Published: February 2011

Welcome to three new puzzles. Solutions to the first two will be published next month; the third is (as yet) unsolved. In each, the issue is how your intuition matches up with the mathematics.
ML
Authors: Gordon Michael J.C.
Published: February 2011

My talk will celebrate Robin Milner's contribution to functional programming via a combination of reminiscences about the early days of ML and speculations about its future.
Using functional programming within an industrial product group
Authors: Scott David , Sharp Richard , Gazagnaire Thomas , Madhavapeddy Anil
Published: February 2011

We present a case-study of using OCaml within a large product development project, focussing on both the technical and non-technical issues that arose as a result. We draw comparisons between the OCaml team and the other teams that worked on the project, providing comparative data on hiring patterns and cross-team code contribution.
Logical types for untyped languages
Authors: Tobin-Hochstadt Sam , Felleisen Matthias
Published: February 2011

Programmers reason about their programs using a wide variety of formal and informal methods. Programmers in untyped languages such as Scheme or Erlang are able to use any such method to reason about the type behavior of their programs. Our type system for Scheme accommodates common reasoning methods by assigning variable occurrences a subtype of their declared type based on the predicates prior to the occurrence, a discipline dubbed
occurrence typing
. It thus enables programmers to enrich existing Scheme code with types, while requiring few changes to the code itself.

Three years of practical experience has revealed serious shortcomings of our type system. In particular, it relied on a system of ad-hoc rules to relate combinations of predicates, it could not reason about subcomponents of data structures, and it could not follow sophisticated reasoning about the relationship among predicate tests, all of which are used in existing code.

In this paper, we reformulate occurrence typing to eliminate these shortcomings. The new formulation derives propositional logic formulas that hold when an expression evaluates to true or false, respectively. A simple proof system is then used to determine types of variable occurrences from these propositions. Our implementation of this revised occurrence type system thus copes with many more untyped programming idioms than the original system.
Distance makes the types grow stronger
Authors: Reed Jason , Pierce Benjamin C.
Published: February 2011

We want assurances that sensitive information will not be disclosed when aggregate data derived from a database is published.
Differential privacy
offers a strong statistical guarantee that the effect of the presence of any individual in a database will be negligible, even when an adversary has auxiliary knowledge. Much of the prior work in this area consists of proving algorithms to be differentially private one at a time; we propose to streamline this process with a functional language whose type system automatically guarantees differential privacy, allowing the programmer to write complex privacy-safe query programs in a flexible and compositional way.

The key novelty is the way our type system captures
function sensitivity
, a measure of how much a function can magnify the distance between similar inputs: well-typed programs not only can't go wrong, they
can't go too far
on nearby inputs. Moreover, by introducing a monad for random computations, we can show that the established definition of differential privacy falls out naturally as a special case of this soundness principle. We develop examples including known differentially private algorithms, privacy-aware variants of standard functional programming idioms, and compositionality principles for differential privacy.
Security-typed programming within dependently typed programming
Authors: Morgenstern Jamie , Licata Daniel R.
Published: February 2011

Several recent security-typed programming languages, such as Aura, PCML5, and Fine, allow programmers to express and enforce access control and information flow policies. In this paper, we show that security-typed programming can be embedded as a library within a general-purpose dependently typed programming language, Agda. Our library, Aglet, accounts for the major features of existing security-typed programming languages, such as decentralized access control, typed proof-carrying authorization, ephemeral and dynamic policies, authentication, spatial distribution, and information flow. The implementation of Aglet consists of the following ingredients: First, we represent the syntax and proofs of an authorization logic, Garg and Pfenning's BL
0
, using dependent types. Second, we implement a proof search procedure, based on a focused sequent calculus, to ease the burden of constructing proofs. Third, we represent computations using a monad indexed by pre- and post-conditions drawn from the authorization logic, which permits ephemeral policies that change during execution. We describe the implementation of our library and illustrate its use on a number of the benchmark examples considered in the literature.
Matching lenses
Authors: Barbosa Davi M.J. , Cretin Julien , Foster Nate , Greenberg Michael , Pierce Benjamin C.
Published: February 2011

Bidirectional programming languages are a practical approach to the view update problem. Programs in these languages, called
lenses
, define both a view and an update policy - i.e., every program can be read as a function mapping sources to views as well as one mapping updated views back to updated sources.

One thorny issue that has not received sufficient attention in the design of bidirectional languages is
alignment
. In general, to correctly propagate an update to a view, a lens needs to match up the pieces of the view with the corresponding pieces of the underlying source, even after data has been inserted, deleted, or reordered. However, existing bidirectional languages either support only simple strategies that fail on many examples of practical interest, or else propose specific strategies that are baked deeply into the underlying theory.

We propose a general framework of
matching lenses
that parameterizes lenses over arbitrary heuristics for calculating alignments. We enrich the types of lenses with "chunks" identifying reorderable pieces of the source and view that should be re-aligned after an update, and we formulate behavioral laws that capture essential constraints on the handling of chunks. We develop a core language of matching lenses for strings, together with a set of "alignment combinators" that implement a variety of alignment strategies.
Total parser combinators
Authors: Danielsson Nils Anders
Published: February 2011

A monadic parser combinator library which guarantees termination of parsing, while still allowing many forms of left recursion, is described. The library's interface is similar to those of many other parser combinator libraries, with two important differences: one is that the interface clearly specifies which parts of the constructed parsers may be infinite, and which parts have to be finite, using dependent types and a combination of induction and coinduction; and the other is that the parser type is unusually informative.

The library comes with a formal semantics, using which it is proved that the parser combinators are as expressive as possible. The implementation is supported by a machine-checked correctness proof.
Rethinking supercompilation
Authors: Mitchell Neil
Published: February 2011

Supercompilation is a program optimisation technique that is particularly effective at eliminating unnecessary overheads. We have designed a new supercompiler, making many novel choices, including different termination criteria and handling of let bindings. The result is a supercompiler that focuses on simplicity, compiles programs quickly and optimises programs well. We have benchmarked our supercompiler, with some programs running more than twice as fast than when compiled with GHC.
Parametricity and dependent types
Authors: Bernardy Jean-Philippe , Jansson Patrik , Paterson Ross
Published: February 2011

Reynolds' abstraction theorem shows how a typing judgement in System F can be translated into a relational statement (in second order predicate logic) about inhabitants of the type. We (in second order predicate logic) about inhabitants of the type. We obtain a similar result for a single lambda calculus (a pure type system), in which terms, types and their relations are expressed. Working within a single system dispenses with the need for an interpretation layer, allowing for an unusually simple presentation. While the unification puts some constraints on the type system (which we spell out), the result applies to many interesting cases, including dependently-typed ones.
Instance chains
Authors: Morris J. Garrett , Jones Mark P.
Published: February 2011

Type classes have found a wide variety of uses in Haskell programs, from simple overloading of operators (such as equality or ordering) to complex invariants used to implement type-safe heterogeneous lists or limited subtyping. Unfortunately, many of the richer uses of type classes require extensions to the class system that have been incompletely described in the research literature and are not universally accepted within the Haskell community.

This paper describes a new type class system, implemented in a prototype tool called
ilab
, that simplifies and enhances Haskell-style type-class programming. In
ilab
, we replace overlapping instances with a new feature,
instance chains
, allowing explicit alternation and failure in instance declarations. We describe a technique for ascribing semantics to type class systems, relating classes, instances, and class constraints (such as kind signatures or functional dependencies) directly to a set-theoretic model of relations on types. Finally, we give a semantics for
ilab
and describe its implementation.
Agility in context
Authors: Hoda Rashina , Kruchten Philippe , Noble James , Marshall Stuart
Published: February 2011

Evangelists for Agile methods strongly encourage all projects to follow every practice of their chosen method. Based on a Grounded Theory study involving 40 participants at 16 organizations, and corroborated by 4 independent case studies, we argue that development methods and practices must be adapted to fit their contexts. Understanding Agility in context will help development teams, their managers, and Agile coaches to adapt development processes to fit their projects' contexts.
From OO to FPGA
Authors: Kou Stephen , Palsberg Jens
Published: February 2011

Consumer electronics today such as cell phones often have one or more low-power FPGAs to assist with energyintensive operations in order to reduce overall energy consumption and increase battery life. However, current techniques for programming FPGAs require people to be specially trained to do so. Ideally, software engineers can more readily take advantage of the benefits FPGAs offer by being able to program them using their existing skills, a common one being object-oriented programming. However, traditional techniques for compiling object-oriented languages are at odds with today's FPGA tools, which support neither pointers nor complex data structures. Open until now is the problem of compiling an object-oriented language to an FPGA in a way that harnesses this potential for huge energy savings. In this paper, we present a new compilation technique that feeds into an existing FPGA tool chain and produces FPGAs with up to almost an order of magnitude in energy savings compared to a low-power microprocessor while still retaining comparable performance and area usage.
Cross-language, type-safe, and transparent object sharing for co-located managed runtimes
Authors: Wegiel Michal , Krintz Chandra
Published: February 2011

As software becomes increasingly complex and difficult to analyze, it is more and more common for developers to use high-level, type-safe, object-oriented (OO) programming languages and to architect systems that comprise multiple components. Different components are often implemented in different programming languages. In state-of-the-art multicomponent, multi-language systems, cross-component communication relies on remote procedure calls (RPC) and message passing. As components are increasingly co-located on the same physical machine to ensure high utilization of multi-core systems, there is a growing potential for using shared memory for cross-language cross-runtime communication.

We present the design and implementation of Co-Located Runtime Sharing (CoLoRS), a system that enables cross-language, cross-runtime type-safe, transparent shared memory. CoLoRS provides object sharing for co-located OO runtimes for both static and dynamic languages. CoLoRS defines a language-neutral object/classmodel,which is a static-dynamic hybrid and enables class evolution while maintaining the space/time efficiency of a static model. CoLoRS uses type mapping and class versioning to transparently map shared types to private types. CoLoRS also contributes a synchronization mechanism and a parallel, concurrent, on-the-fly GC algorithm, both designed to facilitate cross-language cross-runtime object sharing.

We implement CoLoRS in open-source, production-quality runtimes for Python and Java. Our empirical evaluation shows that CoLoRS extensions impose low overhead. We also investigate RPC over CoLoRS and find that using shared memory to implement co-located RPC significantly improves both communication throughput and latency by avoiding data structure serialization.
Monitor optimization via stutter-equivalent loop transformation
Authors: Purandare Rahul , Dwyer Matthew B. , Elbaum Sebastian
Published: February 2011

There has been significant interest in equipping programs with runtime checks aimed at detecting errors to improve fault detection during testing and in the field. Recent work in this area has studied methods for efficiently monitoring a program execution's conformance to path property specifications, e.g., such as those captured by a finite state automaton. These techniques show great promise, but their broad applicability is hampered by the fact that for certain combinations of programs and properties the overhead of checking can slow the program down by up to 3500%.

We have observed that, in many cases, the overhead of runtime monitoring is due to the behavior of program loops. We present a general framework for optimizing the monitoring of loops relative to a property. This framework allows monitors to process a loop in constant-time rather than time that is proportional to the number of loop iterations. We present the results of an empirical study that demonstrates that significant overhead reduction that can be achieved by applying the framework to monitor properties of several large Java programs.
Specifying and implementing refactorings
Authors: Schaefer Max , de Moor Oege
Published: February 2011

Modern IDEs for object-oriented languages like Java provide support for a basic set of simple automated refactorings whose behaviour is easy to describe intuitively. It is, however, surprisingly difficult to specify their behaviour in detail. In particular, the popular precondition-based approach tends to produce somewhat unwieldy descriptions if advanced features of the object language are taken into account. This has resulted in refactoring implementations that are complex, hard to understand, and even harder to maintain, yet these implementations themselves are the only precise "specification" of many refactorings. We have in past work advocated a different approach based on several complementary notions of dependencies that guide the implementation, and on the concept of microrefactorings that structure it. We show in this work that these concepts are powerful enough to provide high-level specifications of many of the refactorings implemented in Eclipse. These specifications are precise enough to serve as the basis of a clean-room reimplementation of these refactorings that is very compact, yet matches Eclipse's for features and outperforms it in terms of correctness.
Component adaptation and assembly using interface relations
Authors: Kell Stephen
Published: February 2011

Software's expense owes partly to frequent
reimplementation
of similar functionality and partly to
maintenance
of patches, ports or components targeting evolving interfaces. More modular non-invasive approaches are unpopular because they entail laborious wrapper code. We propose Cake, a rule-based language describing compositions using
interface relations
. To evaluate it, we compare several existing wrappers with reimplemented Cake versions, finding the latter to be simpler and better modularised.
Type classes as objects and implicits
Authors: Oliveira Bruno C.d.S. , Moors Adriaan , Odersky Martin
Published: February 2011

Type classes were originally developed in Haskell as a disciplined alternative to ad-hoc polymorphism. Type classes have been shown to provide a type-safe solution to important challenges in software engineering and programming languages such as, for example,
retroactive extension
of programs. They are also recognized as a good mechanism for concept-based
generic programming
and, more recently, have evolved into a mechanism for type-level computation.

This paper presents a lightweight approach to type classes in object-oriented (OO) languages with generics using the CONCEPT pattern and
implicits
(a type-directed implicit parameter passing mechanism). This paper also shows how Scala's type system conspires with implicits to enable, and even surpass, many common extensions of the Haskell type class system, making Scala ideally suited for generic programming in the large.
MetaFJig
Authors: Servetto Marco , Zucca Elena
Published: February 2011

We propose a Java-like language where class definitions are first class values and new classes can be derived from existing ones by exploiting the full power of the language itself, used on top of a small set of primitive composition operators, instead of using a fixed mechanism like inheritance.

Hence, compilation requires to perform (meta-)reduction steps, by a process that we call
compile-time execution
. This approach differs from meta-programming techniques available in mainstream languages since it is meta-circular, hence programmers are not required to learn new syntax and idioms.

Compile-time execution is guaranteed to be sound (not to get stuck) by a lightweight technique, where class composition errors are detected dynamically, and conventional typing errors are detected by interleaving typechecking with meta-reduction steps. This allows for a modular approach, that is, compile-time execution is defined, and can be implemented, on top of typechecking and execution of the underlying language. Moreover, programmers can handle errors due to composition operators.

Besides soundness, our technique ensures an additional important property called
meta-level
soundness, that is, typing errors never originate from (meta-)code in already compiled programs.
Reasoning about multiple related abstractions with MultiStar
Authors: van Staden Stephan , Calcagno Cristiano
Published: February 2011

Encapsulated abstractions are fundamental in object-oriented programming. A single class may employ multiple abstractions to achieve its purpose. Such abstractions are often related and combined in disciplined ways. This paper explores ways to express, verify and rely on logical relationships between abstractions. It introduces two general specification mechanisms:
export clauses
for relating abstractions in individual classes, and
axiom clauses
for relating abstractions in a class and all its descendants. MultiStar, an automatic verification tool based on separation logic and abstract predicate families, implements these mechanisms in a multiple inheritance setting. Several verified examples illustrate MultiStar's underlying logic. To demonstrate the flexibility of our approach, we also used MultiStar to verify the core iterator hierarchy of a popular data structure library.
Mostly modular compilation of crosscutting concerns by contextual predicate dispatch
Authors: Chiba Shigeru , Igarashi Atsushi , Zakirov Salikh
Published: February 2011

The modularity of aspect-oriented programming (AOP) has been a controversial issue. To investigate this issue compared with object-oriented programming (OOP), we propose a simple language providing AOP mechanisms, which are enhanced traditional OOP mechanisms. We also present its formal system and then show that programs in this language can be only
mostly
modularly (
i.e.
separately) typechecked and compiled.We mention a source of this unmodularity and discuss whether or not it is appropriate to claim that AOP breaks modularity compared with OOP.
Tribal ownership
Authors: Cameron Nicholas , Noble James , Wrigstad Tobias
Published: February 2011

Tribal Ownership
unifies class nesting and object ownership. Tribal Ownership is based on Tribe, a language with nested classes and object families. In Tribal Ownership, a program's runtime object ownership structure is characterised by the lexical nesting structure of its classes.

We build on a variant of Tribe to present a
descriptive
ownership system, using object nesting to describe heap partitions, but without imposing any restrictions on programming disciplines. We then demonstrate how a range of different
prescriptive ownership policies
can be supported on top of the descriptive Tribal Ownership mechanism; including a novel
owners-as-local-dominators
policy. We formalise our type system and prove soundness and several ownership invariants. The resulting system requires strikingly few annotations, and uses well-understood encapsulation techniques to create ownership systems that should be intuitive for programmers.