bluuebunny/crossref_metadata_2025 huggingface dataset:
Sound propagation over the ground with a random spatially-varying surface admittance
Authors: Dragna Didier , Blanc-Benon Philippe
Published: October 2017

Sound propagation over the ground with a random spatially-varying surface admittance is investigated. Starting from the Green's theorem, a Dyson equation is derived for the coherent acoustic pressure. Under the Bourret approximation, an explicit expression is deduced and an effective admittance that depends on the correlation function of the admittance fluctuations is exhibited. An asymptotic expression at long range is then obtained. Influence of the randomness on the amplitude of the reflection coefficient and on the wavenumbers of the surface wave component is analyzed. Afterwards, numerical simulations of the linearized Euler equations are carried out and the coherent pressure obtained by an ensemble-averaging over 200 realizations of the admittance is found to be in good agreement with the analytical solution. In the considered examples of grounds, the mean intensity is shown to be similar to the intensity in the non-random case, except near interferences that are smoothened out due to randomness. It is however exemplified that the intensity fluctuations can be large, especially near destructive interferences.
Formant-frequency discrimination of synthesized vowels in budgerigars (Melopsittacus undulatus) and humans
Authors: Henry Kenneth S. , Amburgey Kassidy N. , Abrams Kristina S. , Idrobo Fabio , Carney Laurel H.
Published: October 2017

Vowels are complex sounds with four to five spectral peaks known as formants. The frequencies of the two lowest formants, F1and F2, are sufficient for vowel discrimination. Behavioral studies show that many birds and mammals can discriminate vowels. However, few studies have quantified thresholds for formant-frequency discrimination. The present study examined formant-frequency discrimination in budgerigars (Melopsittacus undulatus) and humans using stimuli with one or two formants and a constant fundamental frequency of 200 Hz. Stimuli had spectral envelopes similar to natural speech and were presented with random level variation. Thresholds were estimated for frequency discrimination of F1, F2, and simultaneous F1 and F2 changes. The same two-down, one-up tracking procedure and single-interval, two-alternative task were used for both species. Formant-frequency discrimination thresholds were as sensitive in budgerigars as in humans and followed the same patterns across all conditions. Thresholds expressed as percent frequency difference were higher for F1 than for F2, and were unchanged between stimuli with one or two formants. Thresholds for simultaneous F1 and F2 changes indicated that discrimination was based on combined information from both formant regions. Results were consistent with previous human studies and show that budgerigars provide an exceptionally sensitive animal model of vowel feature discrimination.
A cryofuge for cold-collision experiments with slow polar molecules
Authors: Wu Xing , Gantner Thomas , Koller Manuel , Zeppenfeld Martin , Chervenkov Sotir , Rempe Gerhard
Published: October 2017

Cooling molecules in the spin cycle

A block of ice might look solid, but the molecules inside it are shaking vigorously. Slowing molecules all the way down in the laboratory offers enticing prospects to study and apply their quantum behavior. However, methods to cool dense samples to the necessary temperatures below 1 K have tended to be restricted to rather specialized diatomics. Wu
et al.
present a general cooling technique that applies to a wide range of conventional polar molecules such as methanol, fluoromethane, and ammonia. Their apparatus combines a preliminary cooling step in a buffer gas with a centrifuge that spins the molecules down using electric fields.

Science
, this issue p.
645
Genome Sequence of Fowl Aviadenovirus A Strain JM1/1, Which Caused Gizzard Erosions in Japan
Authors: Thanasut Khompakorn , Fujino Kan , Taharaguchi Motoko , Taharaguchi Satoshi , Shimokawa Fumie , Murakami Masaru , Takase Kozo
Published: October 2017

This study reports the complete genome sequence of fowl aviadenovirus A strain JM1/1, which caused gizzard erosions in broilers occurring in Japan. The JM1/1 genome is 43,809 bp in length and most closely related to the strain chicken embryo lethal orphan (CELO); moreover, multiple site insertions and deletions were found.
Draft Genome Sequence of Lactobacillus plantarum Strain A6, a Strong Acid Producer Isolated from a Vietnamese Fermented Sausage (Nem Chua)
Authors: Golneshin Aida , Gor Mian-Chee , Van Thi Thu Hao , May Bee , Moore Rob J. , Smith Andrew T.
Published: October 2017

Lactobacillus plantarum
strain A6, a strong acid producer, was isolated from a Vietnamese fermented sausage (nem chua). Here, we report the genome sequence of this strain (3,368,579 bp).
Whole-Genome Sequence of Bifidobacterium longum Strain Indica, Isolated from the Gut of a Healthy Indian Adult
Authors: Bag Satyabrata , Ghosh Tarini Shankar , Das Bhabatosh
Published: October 2017

Bifidobacterium longum
, a Gram-positive rod-shaped anaerobic bacterium, inhabits the human gastrointestinal tract and contributes significantly to oligosaccharide production, amino acid metabolism, and protection against intestinal inflammation. Here, we report the whole-genome sequence of
B. longum
, which was isolated from the gastrointestinal tract of a healthy Indian adult.
Draft Genome Sequence of a Picorna-Like Virus Associated with Gill Tissue in Clinically Normal Brook Trout,
Salvelinus fontinalis
Authors: Iwanowicz Luke R. , Iwanowicz Deborah D. , Adams Cynthia R. , Galbraith Heather , Aunins Aaron , Cornman Robert S.
Published: October 2017

Here, we report a draft genome sequence of a picorna-like virus associated with brook trout,
Salvelinus fontinalis
, gill tissue. The draft genome comprises 8,681 nucleotides, excluding the poly(A) tract, and contains two open reading frames. It is most similar to picorna-like viruses that infect invertebrates.
Draft Genome Sequence of
Romboutsia maritimum
sp. nov. Strain CCRI-22766
T
, Isolated from Coastal Estuarine Mud
Authors: Maheux Andrée F. , Boudreau Dominique K. , Bérubé Ève , Boissinot Maurice , Raymond Frédéric , Brodeur Stéphanie , Corbeil Jacques , Brightwell Gale , Broda Dorota , Omar Rabeea F. , Bergeron Michel G.
Published: October 2017

The
Romboutsia maritimum
sp. nov. CCRI-22766
T
strain was isolated from coastal estuarine mud in New Zealand. The genome assembly comprised 2,854,352 bp, with 27.1% G+C content. This is the first documentation that reports the genome sequence of
R. maritimum
.
Complete Genome Sequence of Peste des Petits Ruminants Virus from Georgia, 2016
Authors: Rajko-Nenow Paulina Z. , Cunliffe Tabitha G. , Flannery John T. , Ropiak Honorata M. , Avaliani Lasha , Donduashvili Marina , Baron Michael D. , Batten Carrie A.
Published: October 2017

We report here the complete genome sequence of a peste des petits ruminants virus (PPRV) from the first outbreak of the disease in Georgia in January 2016. Genome sequencing was performed using Illumina next-generation sequencing technology in conjunction with Sanger sequencing. This PPRV/Georgia/Tbilisi/2016 genome sequence clustered within lineage IV PPRV viruses.
Genome Sequences of Coxsackievirus B5 Isolates from Two Children with Meningitis in Australia
Authors: Huang Bixing , Harrower Bruce , Burtonclay Peter , Constantino Tanya , Warrilow David
Published: October 2017

Two coxsackievirus B5 (CVB5) strains were isolated from two children with aseptic meningitis in Australia. Their genomes were sequenced and found to be divergent from the previously reported CVB5 genome sequences, with both having 84% and 97% identities to the closest strains at the nucleotide and amino acid levels, respectively.
Effect of Pokémon GO on incidence of fatal traffic injuries: a population-based quasi-experimental study using the national traffic collisions database in Japan
Authors: Ono Sachiko , Ono Yosuke , Michihata Nobuaki , Sasabuchi Yusuke , Yasunaga Hideo
Published: October 2017

Pokémon GO (Niantic Labs, released on 22 July 2016 in Japan) is an augmented reality game that gained huge popularity worldwide. Despite concern about Pokémon GO–related traffic collisions, the effect of playing Pokémon GO on the incidence of traffic injuries remains unknown. We performed a population-based quasi-experimental study using national data from the Institute for Traffic Accident Research and Data Analysis, Japan. The outcome was incidence of traffic injuries. Of 127 082 000 people in Japan, 886 fatal traffic injuries were observed between 1 June and 31 August in 2016. Regression discontinuity analysis showed a non-significant change in incidence of fatal traffic injuries after the Pokémon GO release (0.017 deaths per million, 95%CI −0.036 to 0.071). This finding was similar to that obtained from a difference-in-differences analysis. Effect of Pokémon GO on fatal traffic injuries may be negligible.
Contemporary endovascular and open aneurysm treatment in the era of flow diversion
Authors: Mazur Marcus D , Taussky Philipp , Park Min S , Couldwell William T
Published: October 2017

Clinical outcomes have improved considerably over the last decade for patients with ruptured and unruptured aneurysms. Modern endovascular techniques, such as flow diversion, are associated with high aneurysm occlusion rates and have become a popular treatment modality for many types of aneurysms. However, the safety and effectiveness of flow diversion has not yet been established in trials comparing it with traditional aneurysm treatments. Moreover, there are some types of aneurysms that may not be appropriate for endovascular coiling, such as wide-necked aneurysms located at branch points of major vessels, large saccular aneurysms with multiple efferent arteries, dolichoectatic aneurysms, large aneurysms with mass effect, when there are technical complications with endovascular treatment, when patients cannot tolerate or have contraindications to antiplatelet therapy or in the setting of a subarachnoid haemorrhage. For these cases, open cerebrovascular surgery remains important. This review provides a discussion on the current trends and evidence for both flow diversion and open cerebrovascular surgery for complex aneurysms that may not be suitable for coiling. We emphasise a continued important role for surgical treatment in certain situations.
Michael Alan Wright
Authors: Morten David , Yarwood John , Taylor Bridget
Published: October 2017

Michael Wright was a respected vet who had great pride in his profession.
Co-seismic stress changes and damage to tunnels in the 23 October 2004 Mid-Niigata Prefecture earthquake
Authors: Kazmi Zaheer Abbas , Konagai Kazuo
Published: October 2017

Recent near-field earthquakes accompanied by large soil deformations have been clouding the notion that mountain tunnels would be safe places during earthquakes. One of the recent eye-openers was the damage to railway tunnels in the 2004 Mid-Niigata Prefecture earthquake. Changes in stresses in the interior of a half-space of stratified sedimentary rocks, as a representative of the earthquake-hit region, are obtained using the authors’ previous works on co-seismic deformations of this region to study the damage mechanism of deeply embedded railway tunnels. The values of square root of the second invariant of the stress deviator tensor, [Formula: see text], and the first invariant of Cauchy stress tensor, [Formula: see text], are compared with the reported damages along the entire stretch of selected tunnels and a very good correlation is observed between the peak values of [Formula: see text] and the damaged sections of the tunnels. A yield surface is defined as the boundary between clusters of points for damaged and undamaged tunnel sections in the scatter diagram of [Formula: see text] and [Formula: see text]. This yield surface and rock–soil deformability can be used to examine the margin of safety of both existing and new tunnels as well as for hazard zonation in a given scenario earthquake.
Physiological and pharmacological inductors of HSP70 enhance the antioxidative defense mechanisms of the liver and pancreas in diabetic rats
Authors: Dimitrovska Maja , Dervisevik Mirsada , Cipanovska Natasa , Gerazova Katerina , Dinevska-Kjovkarovska Suzana , Miova Biljana
Published: October 2017

Heat preconditioning (HP) is a powerful adaptive and protective phenomenon and the heat stress proteins (HSPs) it produces are an important determinant for the development of diabetic complications. Aspirin has been reported to modulate heat shock response in different organisms through increased induction of HSPs and is also known to exert antioxidative and radical scavenging effects in diabetes. We estimated the effect of physiological (heat stress: 45 min at 41 ± 0.5 °C) and pharmacological (aspirin treatment) induction of HSP70 on several parameters of oxidative state in the pancreas and liver of diabetic rats. Diabetes increased HSP70 level and decreased poly(ADP) ribose polymerase (PARP), glutathione (GSH), and glutathione peroxidase (GPx) activities in the pancreas. In the liver, there was reduction of HSP70 level, GSH concentration, and CAT activity, while GPx and GR activity were enhanced. HP of diabetic rats caused an additional increase of HSP70, GSH, and antioxidant enzymes in both organs. Pre-treatment of HP–diabetic animals with aspirin led to an additional increase of PARP and HSP70. Both HP and aspirin, as physiological and pharmacological inductors of HSP70, respectively, enhanced the antioxidative defense mechanisms of the liver and pancreas in diabetic rats.
Climate change and Canada’s north coast: research trends, progress, and future directions
Authors: Ford James D. , Couture Nicole , Bell Trevor , Clark Dylan G.
Published: October 2017

This paper identifies and characterizes current knowledge on climate change impacts, adaptation, and vulnerability for Canada’s northern coastline, outlining key research gaps. Warming temperatures and increased precipitation have been documented across the northern coast, with the rate of sea ice decline ranging from 2.9% to 10.4% per decade. Storm intensity and frequency is increasing, and permafrost is warming across the region. Many of these changes are projected to accelerate in the future, with in excess of 8 °C warming in winter possible under a high-emission scenario by 2081–2100. Vulnerability to these changes differs by region and community, a function of geographic location, nature of climate change impacts, and human factors. Capacity to manage climate change is high in some sectors, such as subsistence harvesting, but is being undermined by long-term societal changes. In other sectors, such as infrastructure and transportation, limitations in climate risk management capacity result in continuing high vulnerabilities. There is evidence that adaptation is taking place in response to experienced and projected impacts, although readiness for adaptation is challenged by limited resources, institutional capacity, and a need for support for adaptation across levels of government. Priority areas for future research include (i) expanding the sectoral and geographic focus of understanding on climate change impacts, adaptation, and vulnerability; (ii) integrating climatic and socio-economic projections into vulnerability and adaptation assessments; (iii) developing an evidence base on adaptation options; and (iv) monitoring and evaluating the effectiveness of adaptation support. Cross-cutting themes for advancing climate change impacts, adaptation, and vulnerability research on the north coast more broadly include the need for greater emphasis on interdisciplinary approaches and cross-cultural collaborations, support for decision-orientated research, and focus on effective knowledge mobilization.
Algebraic aspects of the driven dynamics in the density operator and correlation functions calculation for multi-level open quantum systems
Authors: Bogolubov Nikolai N. , Soldatov Andrey V.
Published: October 2017

Exact and approximate master equations were derived by the projection operator method for the reduced statistical operator of a multi-level quantum system with finite number N of quantum eigenstates interacting with arbitrary external classical fields and dissipative environment simultaneously. It was shown that the structure of these equations can be simplified significantly if the free Hamiltonian driven dynamics of an arbitrary quantum multi-level system under the influence of the external driving fields as well as its Markovian and non-Markovian evolution, stipulated by the interaction with the environment, are described in terms of the SU(N) algebra representation. As a consequence, efficient numerical methods can be developed and employed to analyze these master equations for real problems in various fields of theoretical and applied physics. It was also shown that literally the same master equations hold not only for the reduced density operator but also for arbitrary nonequilibrium multi-time correlation functions as well under the only assumption that the system and the environment are uncorrelated at some initial moment of time. A calculational scheme was proposed to account for these lost correlations in a regular perturbative way, thus providing additional computable terms to the correspondent master equations for the correlation functions.
Theoretical studies of the local structures and spin Hamiltonian parameters for Cu2+ in alkaline earth alumino borate glasses
Authors: Guo Jia-Xing , Wu Shao-Yi , Kuang Min-Quan , Peng Li , Wu Li-Na
Published: October 2017

The local structures and spin Hamiltonian parameters are theoretically studied for Cu[Formula: see text] in alkaline earth alumino borate (XAB, X = Mg, Ca and Sr) glasses by using the perturbation calculations for tetragonally elongated octahedral 3d9 groups. The [Formula: see text] groups are subject to the large relative tetragonal elongation ratios of 15.4%, 13.4% and 13.0% for MgAB, CaAB and SrAB glasses, respectively, arising from the Jahn–Teller effect. The decreasing cubic field parameter Dq, orbital reduction factor k and relative elongation ratio with the increase of the radius of alkaline earth ion X from Mg to Ca or Sr are analyzed for the studied systems in a uniform way.
A New Chaotic Attractor Around a Pre-Located Ring
Authors: Wang Zhen , Xu Zhe , Mliki Ezzedine , Akgul Akif , Pham Viet-Thanh , Jafari Sajad
Published: October 2017

Designing chaotic systems with specific features is a very interesting topic in nonlinear dynamics. However most of the efforts in this area are about features in the structure of the equations, while there is less attention to features in the topology of strange attractors. In this paper, we introduce a new chaotic system with unique property. It has been designed in such a way that a specific property has been injected to it. This new system is analyzed carefully and its real circuit implementation is presented.
Bifurcation Predication in Axial Compressors with Nonuniform Inflow via Deterministic Learning
Authors: Lin Peng , Wang Cong , Wang Min
Published: October 2017

The nonlinear dynamics of fluid instabilities such as rotating stall and surge in axial compressors are typically modeled as subcritical Hopf bifurcations with hysteresis. The bifurcation prediction provides an effective approach to avoid the occurrence of compressor’s instability. In this paper, based on a fluid dynamic model developed recently, a stall precursor detection approach employing deterministic learning (DL) is proposed for bifurcation predication in axial compressors with nonuniform inflow. The stall precursor near the bifurcation can be obtained as the throttle area parameter approaches its critical (or bifurcation) value. Firstly, the system dynamics underlying normal and stall precursor are locally approximated accurately through DL. The obtained knowledge of dynamics is stored in constant radial basis function (RBF) networks. Secondly, a bank of estimators is built up using the stored constant RBF networks to represent the learning normal and stall precursor patterns. By comparing each estimator with a test system, the average [Formula: see text] norms of the residuals are taken as the measure of the dynamical differences between the test system and the learning patterns. The occurrence of stall precursor as a bifurcation predication signal can be rapidly detected according to the smallest residual principle. Finally, simulation results are given to show the effectiveness of stall precursor detection approach.
Infinite Multistability in a Self-Reproducing Chaotic System
Authors: Li Chunbiao , Sprott Julien Clinton , Hu Wen , Xu Yujie
Published: October 2017

Multistability exists in various regimes of dynamical systems and in different combinations, among which there is a special one generated by self-reproduction. In this paper, we describe a method for constructing self-reproducing systems from a unique class of variable-boostable systems whose coexisting attractors reside in the phase space along a specific coordinate axis and any of which can be selected by choosing an initial condition in its corresponding basin of attraction.
Weakness of gravity as illusion which hides true path to unification of gravity with particle physics
Authors: Burinskii Alexander
Published: October 2017

Well known weakness of gravity in particle physics is an illusion caused by underestimation of the role of spin in gravity. Relativistic rotation is inseparable from spin, which for elementary particles is extremely high and exceeds mass on 20–22 orders (in units [Formula: see text]). Such a huge spin generates frame-dragging that distorts space much stronger than mass, and effective scale of gravitational interaction is shifted from Planck to Compton distances. We show that compatibility between gravity and quantum theory can be achieved without modifications of Einstein–Maxwell equations, by coupling to a supersymmetric Higgs model of symmetry breaking and forming a nonperturbative super-bag solution, which generates a gravity-free Compton zone necessary for consistent work of quantum theory. Super-bag is naturally upgraded to Wess–Zumino supersymmetric QED model, forming a bridge to perturbative formalism of conventional QED.
Lorentz violation with a universal minimum speed as foundation of de Sitter relativity
Authors: Cruz Cláudio Nassif , dos Santos Rodrigo Francisco , Amaro de Faria A. C.
Published: October 2017

We aim to investigate the theory of Lorentz violation with an invariant minimum speed called Symmetrical Special Relativity (SSR) from the viewpoint of its metric. Thus, we should explore the nature of SSR-metric in order to understand the origin of the conformal factor that appears in the metric by deforming Minkowski metric by means of an invariant minimum speed that breaks down Lorentz symmetry. So, we are able to realize that there is a similarity between SSR and a new space with variable negative curvature ([Formula: see text]) connected to a set of infinite cosmological constants ([Formula: see text]), working like an extended de Sitter (dS) relativity, so that such extended dS-relativity has curvature and cosmological “constant” varying in time. We obtain a scenario that is more similar to dS-relativity given in the approximation of a slightly negative curvature for representing the current universe having a tiny cosmological constant. Finally, we show that the invariant minimum speed provides the foundation for understanding the kinematics origin of the extra dimension considered in dS-relativity in order to represent the dS-length.
The Leasing Decisions of Startup Firms
Authors: Cotei Carmen , Farhat Joseph
Published: October 2017

Small business owners use a variety of bootstrap financing methods to acquire the needed resources necessary to survive and eventually grow their businesses. One such method is to lease equipment and/or machinery. Leasing is a viable alternative to bank financing and for small businesses, leasing is a flexible strategy to preserve cash. In this study, we analyze the impact of asset specificity and growth opportunities on leasing decisions of a large cohort of startup businesses. To test our hypotheses, we use a unique dataset provided by the Kauffman Foundation.1Our longitudinal analyses show that startups with unique/specific assets have a lower propensity to lease whereas startups with high growth opportunities are more likely to lease their assets. We also argue that the owners’ demographic and socioeconomic characteristics are likely to impact their individual risk-taking behavior. Thus, factors such as owners’ experience, education, age, gender, and race are likely to impact the decision to lease assets. Our results show that owners’ characteristics do have a significant impact on these decisions. The findings reveal that female and older entrepreneurs as well as highly educated owners are less likely to lease. Our work advances prior research on the determinants of leasing in large, publicly traded firms and provides additional insights on entrepreneurial bootstrapping.
Upper Ordovician and Silurian ash beds in the Holy Cross Mountains, Poland: preservation in mudrock facies and relation to atmospheric circulation in the Southern Hemisphere
Authors: Trela Wieslaw , Bąk Ewelina , Pańczyk Magdalena
Published: October 2017

Numerous volcanic ash beds (K-bentonite) are recognized globally in Ordovician to Early Devonian sedimentary successions, and are important for regional stratigraphic correlations. Relatively little, however, is understood of the origin and transport of these ash deposits. Here, we examine ash beds preserved in the Upper Ordovician and Silurian dark shales and mudstones of the Holy Cross Mountains, Poland, and discuss their origin in the context of contemporaneous tectonic configurations. The Ordovician ash beds occur in the upper Sandbian and Katian mudrock succession, whereas the Silurian K-bentonites form prominent beds in the upper Wenlock and lower Ludlow graptolite shales. Their various thickness and irregular distribution reflect fluctuation of volcanic activity and contribution of physical and biogenic factors in their preservation. Deposition under dysoxic or anoxic conditions and relatively rapid burial by muddy sediment seem to be dominant factors preventing physical and biological reworking and mixing of the volcanic ash. The Upper Ordovician ash beds in the Holy Cross Mountains, as well as the Baltoscandian K-bentonites, appear to be accumulated from pyroclastic material delivered by westerlies of the Southern Hemisphere from the Avalonian volcanoes. In the Silurian, the distribution of pyroclastic material was controlled by SE trade winds, and therefore the source area for the Wenlock and Ludlow K-bentonites in the Holy Cross Mountains appears to have been an active subduction zone developed close to the southeastern side of Baltica. However, the delivery of volcanic ash to the central part of Baltica might have been strongly affected by climatically driven latitudinal migration of the Intertropical Convergence Zone.
3D structural and thermal modelling of Mesozoic petroleum systems in the Po Valley Basin, northern Italy
Authors: Turrini Claudio , Bosica Barbara , Ryan Paul , Shiner Peter , Lacombe Olivier , Roure François
Published: October 2017

1D and 3D basin modelling was performed to investigate the Mesozoic carbonate petroleum systems of the Po Valley Basin (northern Italy), through integration of a recent 3D structural model of the study area with the distribution of potential Triassic source rocks, rock properties and heat flow models.

Results from standard 1D maturity models show significant overprediction of the thermal maturity of deep Triassic carbonates in the western Po Valley, unless the effect of the substantial overpressure observed in these sequences is incorporated into the model. In order to further test this observation, two thermal scenarios were applied to the Po Valley 3D geo-volume: one based on the actual geological heat flow and a second model based on a reduced heat flow as a proxy for the delaying effect of overpressure on hydrocarbon maturation. The predictions of these two models were then compared with the observed hydrocarbon distribution in the western Po Valley.

Both thermal scenarios are broadly consistent with the observed hydrocarbon distribution at the scale of the basin but, in detail, the overpressure model provides a better match between the predicted charge available from the kitchen area's post-critical moment and observed volumes of hydrocarbons initially in place within the traps, as well as with the observed and predicted hydrocarbon phases, as measured by the gas/oil ratio (GOR) of the fluids. Overpressure probably significantly delayed hydrocarbon maturation in the western domain of the basin, confirming results from previous studies.

Beyond regional implications, and despite its relative simplicity and inherent uncertainties, the adopted approach demonstrates the potential of a consistent 3D integration of the thermostructural history of sedimentary basins to constrain the geometry and structural evolution of hydrocarbon-bearing traps, as well as the generation and migration of hydrocarbons into these traps.
Synthesizing configuration file specifications with association rule learning
Authors: Santolucito Mark , Zhai Ennan , Dhodapkar Rahul , Shim Aaron , Piskac Ruzica
Published: October 2017

System failures resulting from configuration errors are one of the major reasons for the compromised reliability of today's software systems. Although many techniques have been proposed for configuration error detection, these approaches can generally only be applied after an error has occurred. Proactively verifying configuration files is a challenging problem, because 1) software configurations are typically written in poorly structured and untyped “languages”, and 2) specifying rules for configuration verification is challenging in practice. This paper presents ConfigV, a verification framework for general software configurations. Our framework works as follows: in the pre-processing stage, we first automatically derive a specification. Once we have a specification, we check if a given configuration file adheres to that specification. The process of learning a specification works through three steps. First, ConfigV parses a training set of configuration files (not necessarily all correct) into a well-structured and probabilistically-typed intermediate representation. Second, based on the association rule learning algorithm, ConfigV learns rules from these intermediate representations. These rules establish relationships between the keywords appearing in the files. Finally, ConfigV employs rule graph analysis to refine the resulting rules. ConfigV is capable of detecting various configuration errors, including ordering errors, integer correlation errors, type errors, and missing entry errors. We evaluated ConfigV by verifying public configuration files on GitHub, and we show that ConfigV can detect known configuration errors in these files.
Practical initialization race detection for JavaScript web applications
Authors: Adamsen Christoffer Quist , Møller Anders , Tip Frank
Published: October 2017

Event races are a common source of subtle errors in JavaScript web applications. Several automated tools for detecting event races have been developed, but experiments show that their accuracy is generally quite low. We present a new approach that focuses on three categories of event race errors that often appear during the initialization phase of web applications: form-input-overwritten errors, late-event-handler-registration errors, and access-before-definition errors. The approach is based on a dynamic analysis that uses a combination of adverse and approximate execution. Among the strengths of the approach are that it does not require browser modifications, expensive model checking, or static analysis.

In an evaluation on 100 widely used websites, our tool InitRacer reports 1085 initialization races, while providing informative explanations of their causes and effects. A manual study of 218 of these reports shows that 111 of them lead to uncaught exceptions and at least 47 indicate errors that affect the functionality of the websites.
Verifying spatial properties of array computations
Authors: Orchard Dominic , Contrastin Mistral , Danish Matthew , Rice Andrew
Published: October 2017

Arrays computations are at the core of numerical modelling and computational science applications. However, low-level manipulation of array indices is a source of program error. Many practitioners are aware of the need to ensure program correctness, yet very few of the techniques from the programming research community are applied by scientists. We aim to change that by providing targetted lightweight verification techniques for scientific code. We focus on the all too common mistake of array offset errors as a generalisation of off-by-one errors. Firstly, we report on a code analysis study on eleven real-world computational science code base, identifying common idioms of array usage and their spatial properties. This provides much needed data on array programming idioms common in scientific code. From this data, we designed a lightweight declarative specification language capturing the majority of array access patterns via a small set of combinators. We detail a semantic model, and the design and implementation of a verification tool for our specification language, which both checks and infers specifications. We evaluate our tool on our corpus of scientific code. Using the inference mode, we found roughly 87,000 targets for specification across roughly 1.1 million lines of code, showing that the vast majority of array computations read from arrays in a pattern with a simple, regular, static shape. We also studied the commit logs of one of our corpus packages, finding past bug fixes for which our specification system distinguishes the change and thus could have been applied to detect such bugs.
Reasoning on divergent computations with coaxioms
Authors: Ancona Davide , Dagnino Francesco , Zucca Elena
Published: October 2017

Coaxioms have been recently introduced to enhance the expressive power of inference systems, by supporting interpretations which are neither purely inductive, nor coinductive. This paper proposes a novel approach based on coaxioms to capture divergence in semantic definitions by allowing inductive and coinductive semantic rules to be merged together for defining a unique semantic judgment. In particular, coinduction is used to derive a special result which models divergence. In this way, divergent, terminating, and stuck computations can be properly distinguished even in semantic definitions where this is typically difficult, as in big-step style. We show how the proposed approach can be applied to several languages; in particular, we first illustrate it on the paradigmatic example of the λ-calculus, then show how it can be adopted for defining the big-step semantics of a simple imperative Java-like language. We provide proof techniques to show classical results, including equivalence with small-step semantics, and type soundness for typed versions of both languages.
DéjàVu: a map of code duplicates on GitHub
Authors: Lopes Cristina V. , Maj Petr , Martins Pedro , Saini Vaibhav , Yang Di , Zitny Jakub , Sajnani Hitesh , Vitek Jan
Published: October 2017

Previous studies have shown that there is a non-trivial amount of duplication in source code. This paper analyzes a corpus of 4.5 million non-fork projects hosted on GitHub representing over 428 million files written in Java, C++, Python, and JavaScript. We found that this corpus has a mere 85 million unique files. In other words, 70% of the code on GitHub consists of clones of previously created files. There is considerable variation between language ecosystems. JavaScript has the highest rate of file duplication, only 6% of the files are distinct. Java, on the other hand, has the least duplication, 60% of files are distinct. Lastly, a project-level analysis shows that between 9% and 31% of the projects contain at least 80% of files that can be found elsewhere. These rates of duplication have implications for systems built on open source software as well as for researchers interested in analyzing large code bases. As a concrete artifact of this study, we have created DéjàVu, a publicly available map of code duplicates in GitHub repositories.
Data-driven context-sensitivity for points-to analysis
Authors: Jeong Sehun , Jeon Minseok , Cha Sungdeok , Oh Hakjoo
Published: October 2017

We present a new data-driven approach to achieve highly cost-effective context-sensitive points-to analysis for Java. While context-sensitivity has greater impact on the analysis precision and performance than any other precision-improving techniques, it is difficult to accurately identify the methods that would benefit the most from context-sensitivity and decide how much context-sensitivity should be used for them. Manually designing such rules is a nontrivial and laborious task that often delivers suboptimal results in practice. To overcome these challenges, we propose an automated and data-driven approach that learns to effectively apply context-sensitivity from codebases. In our approach, points-to analysis is equipped with a parameterized and heuristic rules, in disjunctive form of properties on program elements, that decide when and how much to apply context-sensitivity. We present a greedy algorithm that efficiently learns the parameter of the heuristic rules. We implemented our approach in the Doop framework and evaluated using three types of context-sensitive analyses: conventional object-sensitivity, selective hybrid object-sensitivity, and type-sensitivity. In all cases, experimental results show that our approach significantly outperforms existing techniques.
Automatically generating features for learning program analysis heuristics for C-like languages
Authors: Chae Kwonsoo , Oh Hakjoo , Heo Kihong , Yang Hongseok
Published: October 2017

We present a technique for automatically generating features for data-driven program analyses. Recently data-driven approaches for building a program analysis have been developed, which mine existing codebases and automatically learn heuristics for finding a cost-effective abstraction for a given analysis task. Such approaches reduce the burden of the analysis designers, but they do not remove it completely; they still leave the nontrivial task of designing so called features to the hands of the designers. Our technique aims at automating this feature design process. The idea is to use programs as features after reducing and abstracting them. Our technique goes through selected program-query pairs in codebases, and it reduces and abstracts the program in each pair to a few lines of code, while ensuring that the analysis behaves similarly for the original and the new programs with respect to the query. Each reduced program serves as a boolean feature for program-query pairs. This feature evaluates to true for a given program-query pair when (as a program) it is included in the program part of the pair. We have implemented our approach for three real-world static analyses. The experimental results show that these analyses with automatically-generated features are cost-effective and consistently perform well on a wide range of programs.
Geo-distribution of actor-based services
Authors: Bernstein Philip A. , Burckhardt Sebastian , Bykov Sergey , Crooks Natacha , Faleiro Jose M. , Kliot Gabriel , Kumbhare Alok , Rahman Muntasir Raihan , Shah Vivek , Szekeres Adriana , Thelin Jorgen
Published: October 2017

Many service applications use actors as a programming model for the middle tier, to simplify synchronization, fault-tolerance, and scalability. However, efficient operation of such actors in multiple, geographically distant datacenters is challenging, due to the very high communication latency. Caching and replication are essential to hide latency and exploit locality; but it is not a priori clear how to combine these techniques with the actor programming model.

We present Geo, an open-source geo-distributed actor system that improves performance by caching actor states in one or more datacenters, yet guarantees the existence of a single latest version by virtue of a distributed cache coherence protocol. Geo's programming model supports both volatile and persistent actors, and supports updates with a choice of linearizable and eventual consistency. Our evaluation on several workloads shows substantial performance benefits, and confirms the advantage of supporting both replicated and single-instance coherence protocols as configuration choices. For example, replication can provide fast, always-available reads and updates globally, while batching of linearizable storage accesses at a single location can boost the throughput of an order processing workload by 7x.
Project snowflake: non-blocking safe manual memory management in .NET
Authors: Parkinson Matthew , Vytiniotis Dimitrios , Vaswani Kapil , Costa Manuel , Deligiannis Pantazis , McDermott Dylan , Blankstein Aaron , Balkind Jonathan
Published: October 2017

Garbage collection greatly improves programmer productivity and ensures memory safety. Manual memory management on the other hand often delivers better performance but is typically unsafe and can lead to system crashes or security vulnerabilities. We propose integrating safe manual memory management with garbage collection in the .NET runtime to get the best of both worlds. In our design, programmers can choose between allocating objects in the garbage collected heap or the manual heap. All existing applications run unmodified, and without any performance degradation, using the garbage collected heap.

Our programming model for manual memory management is flexible: although objects in the manual heap can have a single owning pointer, we allow deallocation at any program point and concurrent sharing of these objects amongst all the threads in the program. Experimental results from our .NET CoreCLR implementation on real-world applications show substantial performance gains especially in multithreaded scenarios: up to 3x savings in peak working sets and 2x improvements in runtime.
Formal and Informal Contracting: Theory and Evidence
Authors: Gil Ricard , Zanarone Giorgio
Published: October 2017

In this article, we review the emerging economic literature on formal and informal contracting. Two patterns emerge from this literature. First, the use of informal contracts to complement formal ones is widespread, both within and between firms. Second, informal contracts are limited by the expectation of future collaborations between the parties. Our review suggests that there are significant opportunities for further integrated research in economics, law, and social sciences to enhance our understanding of the interaction between formal and informal contracting within firms, as well as in nonfirm organizations.
What Unions Do for Regulation
Authors: Morantz Alison D.
Published: October 2017

The question of how organized labor affects the content, enforcement, and outcomes of regulation is especially timely in an era in which protective laws and regulations are being scaled back or minimally enforced and union membership is in decline. This article surveys literature from a wide array of regulatory domains—antidiscrimination, environmental protection, product quality, corporate governance, law enforcement, tax compliance, minimum wage and overtime protection, and occupational safety and health—in an effort to identify common findings on what unions do for regulation. Literature on the topic has taken up five questions: how labor unions affect the passage of protective laws and regulations; how they affect the outcomes that regulators target; how they affect the intensity of regulatory enforcement; the specific activities and channels of influence they use to influence regulated outcomes; and the role they play in self-regulation. Drawing on empirical literature from the domains listed, I review and analyze literature on each of these questions and offer several conclusions and suggestions for future research.
Dietary copper-fructose interactions alter gut microbial activity in male rats
Authors: Song Ming , Li Xiaohong , Zhang Xiang , Shi Hongxue , Vos Miriam B. , Wei Xiaoli , Wang Yuhua , Gao Hong , Rouchka Eric C. , Yin Xinmin , Zhou Zhanxiang , Prough Russell A. , Cave Matthew C. , McClain Craig J.
Published: October 2017

Dietary copper-fructose interactions contribute to the development of nonalcoholic fatty liver disease (NAFLD). Gut microbiota play critical roles in the pathogenesis of NAFLD. The aim of this study was to determine the effect of different dietary doses of copper and their interactions with high fructose on gut microbiome. Male weanling Sprague-Dawley rats were fed diets with adequate copper (6 ppm CuA), marginal copper (1.5 ppm CuM) (low copper), or supplemented copper (20 ppm CuS) (high copper) for 4 wk. Deionized water or deionized water containing 30% fructose (wt/vol) was given ad libitum. Copper status, liver enzymes, gut barrier function, and gut microbiome were evaluated. Both low- and high-copper diets led to liver injury in high-fructose-fed rats, and this was associated with gut barrier dysfunction, as shown by the markedly decreased tight junction proteins and increased gut permeability. 16S rDNA sequencing analysis revealed distinct alterations of the gut microbiome associated with dietary low- and high-copper/high-fructose feeding. The common features of the alterations of the gut microbiome were the increased abundance of Firmicutes and the depletion of Akkermansia. However, they differed mainly within the phylum Firmicutes. Our data demonstrated that a complex interplay among host, microbes, and dietary copper-fructose interaction regulates gut microbial metabolic activity, which may contribute to the development of liver injury and hepatic steatosis. The distinct alterations of gut microbial activity, which were associated with the different dietary doses of copper and fructose, imply that separate mechanism(s) may be involved.

NEW & NOTEWORTHY First, dietary low- and high-copper/high-fructose-induced liver injury are associated with distinct alterations of gut microbiome. Second, dietary copper level plays a critical role in maintaining the gut barrier integrity, likely by acting on the intestinal tight junction proteins and the protective commensal bacteria Akkermansia. Third, the alterations of gut microbiome induced by dietary low and high copper with or without fructose differ mainly within the phylum Firmicutes.