bluuebunny/crossref_metadata_2025 huggingface dataset:
Expression of fungal acetyl xylan esterase in Arabidopsis thaliana improves saccharification of stem lignocellulose
Authors: Pawar Prashant Mohan‐Anupama , Derba‐Maceluch Marta , Chong Sun‐Li , Gómez Leonardo D. , Miedes Eva , Banasiak Alicja , Ratke Christine , Gaertner Cyril , Mouille Grégory , McQueen‐Mason Simon J. , Molina Antonio , Sellstedt Anita , Tenkanen Maija , Mellerowicz Ewa J.
Published: May 2015

Cell wall hemicelluloses and pectins are O‐acetylated at specific positions, but the significance of these substitutions is poorly understood. Using a transgenic approach, we investigated how reducing the extent of O‐acetylation in xylan affects cell wall chemistry, plant performance and the recalcitrance of lignocellulose to saccharification. The Aspergillus niger acetyl xylan esterase AnAXE1 was expressed in Arabidopsis under the control of either the constitutively expressed 35S CAMV promoter or a woody‐tissue‐specific GT43B aspen promoter, and the protein was targeted to the apoplast by its native signal peptide, resulting in elevated acetyl esterase activity in soluble and wall‐bound protein extracts and reduced xylan acetylation. No significant alterations in cell wall composition were observed in the transgenic lines, but their xylans were more easily digested by a β‐1,4‐endoxylanase, and more readily extracted by hot water, acids or alkali. Enzymatic saccharification of lignocellulose after hot water and alkali pretreatments produced up to 20% more reducing sugars in several lines. Fermentation by Trametes versicolor of tissue hydrolysates from the line with a 30% reduction in acetyl content yielded ~70% more ethanol compared with wild type. Plants expressing 35S:AnAXE1 and pGT43B:AnAXE1 developed normally and showed increased resistance to the biotrophic pathogen Hyaloperonospora arabidopsidis, probably due to constitutive activation of defence pathways. However, unintended changes in xyloglucan and pectin acetylation were only observed in 35S:AnAXE1‐expressing plants. This study demonstrates that postsynthetic xylan deacetylation in woody tissues is a promising strategy for optimizing lignocellulosic biomass for biofuel production.
Effect of high temperature on the production of 2n pollen grains in diploid roses and obtaining tetraploids via unilateral polyploidization
Authors: Crespel Laurent , Le Bras Camille , Relion Daniel , Roman Hanaé , Morel Philippe
Published: May 2015

To integrate the gene pool of a wild species (primarily diploid) into a cultivated pool (primarily tetraploid), a crossing between a dihaploid cultivated rose and a hybrid of Rosa wichurana allowed to obtain interspecific diploid hybrids that produced 2n pollen grains. A return to a tetraploid level sought by breeders can then be considered using sexual polyploidization, obtained by crossing a tetraploid cultivated rose with these hybrids. Application of a high‐temperature regime led to a small but significant increase in the percentage of 2n pollen grains in these hybrids of up to 4.6%. This result was obtained by applying high temperatures close to 32°C during the day to plants cultivated in a glasshouse during recurrent cycles of bloom. Crosses were made between an unreleased tetraploid hybrid tea rose, as a female, and the diploid hybrid that produces the most 2n pollen grains. Tetraploid (42.1%) and triploid (57.9%) offspring were obtained. The use of these 2n pollen grains of the first division restitution type should facilitate the introgression of complex traits of interest.
Performance and ERP components in the equiprobable go/no‐go task: Inhibition in children
Authors: Barry Robert J. , De Blasio Frances M.
Published: May 2015

The equiprobable go/no‐go task lacks the dominant go imperative found in the usual go/no‐go task, and hence we previously regarded it as involving little inhibition. However, children have relative difficulty with this task, and demonstrate large frontal no‐go N2s. We investigated whether this child N2 plays an inhibitory role, using performance measures to illuminate the link between N2 and inhibition. Forty children aged 8 to 13 were presented with four stimulus blocks each containing 75 go and 75 no‐go tone stimuli in random order. A temporal PCA with unrestricted varimax rotation quantified the mean go and no‐go ERP component amplitudes. Most identified components were differentially enhanced to go or no‐go as in adults, supporting a previously proposed differential processing schema. Between subjects, larger frontocentral no‐go N2bs were associated with fewer commission errors. Hence, the no‐go N2b in this paradigm can be interpreted as an individual marker of inhibition in children.
How Not to Increase Participation in Local Government: The Advantages of Experiments When Testing Policy Interventions
Authors: Arceneaux Kevin , Butler Daniel M.
Published: May 2015

Local governments benefit from nonelected committees that provide citizen input on important issues. Although these committees offer a valuable tool for policy makers, they suffer from low participation and tend to underrepresent economically disadvantaged citizens. This article reports the results of a randomized survey experiment that evaluated the relative effectiveness of offering social recognition or skills training. The findings show that entreaties to participate premised on gaining social recognition had no effect on willingness to participate and that offers to provide training actually decreased citizens’ willingness to participate, especially among economically disadvantaged citizens. Even though these approaches may hold promise, this particular policy intervention did not live up to that promise. The article concludes with a discussion of the importance of testing policy interventions before wide‐scale implementation and the utility of randomized experiments in this process.
Risk Matrix Integrating Risk Attitudes Based on Utility Theory
Authors: Ruan Xin , Yin Zhiyi , Frangopol Dan M.
Published: May 2015

Recent studies indicate that absence of the consideration of risk attitudes of decisionmakers in the risk matrix establishment process has become a major limitation. In order to evaluate risk in a more comprehensive manner, an approach to establish risk matrices that integrates risk attitudes based on utility theory is proposed. There are three main steps within this approach: (1) describing risk attitudes of decisionmakers by utility functions, (2) bridging the gap between utility functions and the risk matrix by utility indifference curves, and (3) discretizing utility indifference curves. A complete risk matrix establishment process based on practical investigations is introduced. This process utilizes decisionmakers’ answers to questionnaires to formulate required boundary values for risk matrix establishment and utility functions that effectively quantify their respective risk attitudes.
Hospitalisation impacts on oral hygiene: an audit of oral hygiene in a metropolitan health service
Authors: Danckert Rachael , Ryan Anna , Plummer Virginia , Williams Cylie
Published: May 2015

Background

Poor oral health has been associated with systemic diseases, morbidity and mortality. Many patients in hospital environments are physically compromised and rely upon awareness and assistance from health professionals for the maintenance or improvement of their oral health. This study aimed to identify whether common individual and environment factors associated with hospitalisation impacted on oral hygiene.

Methods

Data were collected during point prevalence audits of patients in the acute and rehabilitation environments on three separate occasions. Data included demographic information, plaque score, presence of dental hygiene products, independence level and whether nurse assistance was documented in the health record.

Results

Data were collected for 199 patients. A higher plaque score was associated with not having a toothbrush (p = 0.002), being male (p = 0.007), being acutely unwell (p = 0.025) and requiring nursing assistance for oral hygiene (p = 0.002). There was fair agreement between the documentation of requiring assistance for oral care and the patient independently able to perform oral hygiene (ICC = 0.22).

Conclusion

Oral hygiene was impacted by factors arising from hospitalisation, for those without a toothbrush and male patients of acute wards. Establishment of practices that increase awareness and promote good oral health should be prioritised.
‘A Common Sense of the Times’? Neo‐liberalism and Changing Public Opinion in New Zealand and the UK
Authors: Humpage Louise
Published: May 2015

Neo‐liberalism represents a significant and enduring shift in the politics shaping social policy. Although frequently ascribed a hegemonic, all‐powerful status that focuses our attention on the coherence found in neo‐liberal policies, this article builds on scholarly work highlighting variegation in the neo‐liberal project across different policy areas, national settings and time periods. Specifically, it employs Peck's and Tickell's (2002) view that neo‐liberalism has gone through multiple phases in response to both external and internal crises as an entry point for studying neo‐liberalism's impact on public support for the welfare state. Drawing upon New Zealand and British attitudinal data, the article argues that public reactions to an early period of retrenchment (‘roll‐back’ neo‐liberalism) differ from those reported in the ‘roll‐out’ or embedding phase of neo‐liberalism implemented by Third Way Labour Governments in both countries. Indeed, continuing public support in many policy areas arguably contributed to the internal crisis that provoked an adaptation to the neo‐liberal project. The article further explores public support for the welfare state following the external crisis provoked by the financial meltdown of 2008–09 asking whether New Zealand and British attitudes showed signs of resisting austerity measures or whether they, instead, indicated a third, ‘roll‐over’ period of neo‐liberalism where the public accepted not only a neo‐liberal economic agenda but also the need for further retrenchment of the welfare state. Conclusions about the politics of social policy at the level of public opinion offer both good and bad news for welfare state advocates.
Empowering the People: Public Responses to Welfare Policy Change
Authors: Bendz Anna
Published: May 2015

How and when does welfare policy contribute to shape public opinion? This article departs from the policy feedback research tradition and seeks to contribute to the understanding of how policy influences public opinion (public responsiveness). The argument here suggests that personal experiences in terms of empowerment condition the dynamics between policy and opinion. The empirical case concerns the implementation of a consumer's choice model in Swedish primary health care, which resulted an intended increase in private health care centres. In this case, empowerment is assumed to be enhanced by increased exit options and freedom of choice. The specific question in the analysis is whether citizens who have empowering experiences, as a consequence of the reform, are more likely to be positive towards further privatization of welfare services. The results show few effects in general, but there seems to be a correlation between the experience of exiting and more positive attitudes towards privatization.
Efficacy and community effectiveness of larvivorous fish for dengue vector control
Authors: Han W. W. , Lazaro A. , McCall P. J. , George L. , Runge‐Ranzinger S. , Toledo J. , Velayudhan R. , Horstick O.
Published: May 2015

Objective

To evaluate the efficacy and community effectiveness of larvivorous fish for the control of dengue vectors and dengue transmission, when used as a single agent or in combination with other vector control methods.

Method

Comprehensive literature search of published and grey literature using PubMed, EMBASE (DMDI), Web of Science, WHOLIS, WILEY, LILACS, GIFT, Cochrane Library, ELDIS, New York Academy of Medicine Grey Literature Report and Google. All results were checked for duplicates and examined for eligibility. Methodological quality of the studies was assessed using RoBANS.

Results

Thirteen articles were considered eligible for inclusion. Incorporating a wide range of interventions and outcome measures, three were efficacy studies and 10 assessed community effectiveness. None of the studies were randomised or cluster‐randomised controlled trials. All three efficacy studies and seven community effectiveness studies investigated fish as a single agent. All efficacy studies reported elimination of Aedes larvae from treated containers, while community effectiveness studies reported reductions in immature vector stages, two of which also detected a continuous decline over 2 years. An impact on adult mosquitoes was shown in only two community effectiveness studies. Reductions in dengue cases following intervention were reported in two studies, but it was not possible to attribute this to the intervention.

Conclusion

While the use of larvivorous fish as a single agent or in combination with other control measures could lead to reductions in immature vector stages, considerable limitations in all the studies restricted any conclusions with respect to the evaluation of community effectiveness. Evidence for the community effectiveness of larvivorous fish as a single agent remains minimal and cluster‐randomised controlled studies that include the assessment of impact on dengue are recommended.
Augmented endothelial l‐arginine transport ameliorates pressure‐overload‐induced cardiac hypertrophy
Authors: Rajapakse Niwanthi W. , Johnston Tamara , Kiriazis Helen , Chin‐Dusting Jaye P. , Du Xiao‐Jun , Kaye David M.
Published: May 2015

New Findings

What is the central question of this study?

What is the potential role of endothelial NO production via overexpression of the l‐arginine transporter, CAT1, as a mitigator of cardiac hypertrophy?

What is the main finding and its importance?

Augmentation of endothelium‐specific l‐arginine transport via CAT1 can attenuate pressure‐overload‐dependent cardiac hypertrophy and fibrosis. Our findings support the conclusion that interventions that improve endothelial l‐arginine transport may provide therapeutic utility in the setting of myocardial hypertrophy. Such modifications may be introduced by exercise training or locally delivered gene therapy, but further experimental and clinical studies are required.

Endothelial dysfunction has been postulated to play a central role in the development of cardiac hypertrophy, probably as a result of reduced NO bioavailability. We tested the hypothesis that increased endothelial NO production, mediated by increased l‐arginine transport, could attenuate pressure‐overload‐induced cardiac hypertrophy. Echocardiography and blood pressure measurements were performed 15 weeks after transverse aortic constriction (TAC) in wild‐type (WT) mice (n = 12) and in mice with endothelium‐specific overexpression of the l‐arginine transporter, CAT1 (CAT+; n = 12). Transverse aortic constriction induced greater increases in heart weight to body weight ratio in WT (by 47%) than CAT+ mice (by 25%) compared with the respective controls (P ≤ 0.05). Likewise, the increase in left ventricular wall thickness induced by TAC was significantly attenuated in CAT+ mice (P = 0.05). Cardiac collagen type I mRNA expression was greater in WT mice with TAC (by 22%; P = 0.03), but not in CAT+ mice with TAC, compared with the respective controls. Transverse aortic constriction also induced lesser increases in β‐myosin heavy chain mRNA expression in CAT+ mice compared with WT (P ≤ 0.05). Left ventricular systolic pressure after TAC was 36 and 39% greater in WT and CAT+ mice, respectively, compared with the respective controls (P ≤ 0.001). Transverse aortic constriction had little effect on left ventricular end‐diastolic pressure in both genotypes. Taken together, these data indicate that augmenting endothelial function by overexpression of l‐arginine transport can attenuate pressure‐overload‐induced cardiac hypertrophy.
Application of Hyper-Dual Numbers to Multibody Kinematics
Authors: Cohen Avraham , Shoham Moshe
Published: May 2015

Hyper-dual numbers (HDNs) are applied in this paper to multibody kinematics. First, the hyper-dual angle that encompasses a body's position, orientation, as well as its velocity, is defined as an element of the hyper-dual transformation matrix. Then, the “automatic differentiation” feature of the dual numbers is used to obtain the second derivative of a body pose. The body's velocity and acceleration are obtained from the elements of the hyper-dual transformation matrix by algebraic manipulations only, with no need for further time derivatives of the body pose. A robot manipulator is presented as an exemplary application of HDNs to multibody kinematics.
Fabrication and electrical performance of through silicon via interconnects filled with a copper/carbon nanotube composite
Authors: Feng Ying , Burkett Susan L.
Published: May 2015

In this work, through silicon vias (TSVs) were fabricated using a materials system consisting of a composite of copper (Cu) and vertically grown carbon nanotubes (CNTs) as a possible solution to the problems encountered when using Cu-based interconnects. A metallic seed layer, tungsten, was deposited prior to CNT growth. Tungsten replaces Cu as a seed layer due to the thermal sensitivity of Cu at CNT growth temperatures. CNTs were grown both on the wafer surface and inside the silicon vias by chemical vapor deposition. A self-directed densification process was applied to modify the shape of the CNTs from a forest with equal top and bottom dimensions into bundles with a significantly smaller dimension at the top compared to the bottom. This process maximizes the contact area between the Cu electroplating solution and the CNTs. Cu was deposited by periodic pulse electroplating after CNT growth to form the Cu/CNT composite. Wafer thinning and polishing completed the TSV fabrication forming a test configuration to evaluate electrical performance. Experimental results were compared for interconnects filled with pure Cu to those filled with the Cu/CNT composite. The results indicate potential application of the Cu/CNT composite as a TSV interconnect material.
Direct effects of lightning in temperate forests: a review and preliminary survey in a hemlock–hardwood forest of the northern United States
Authors: Yanoviak Stephen P. , Gora Evan M. , Fredley Jennifer , Bitzer Phillip M. , Muzika Rose-Marie , Carson Walter P.
Published: May 2015

Lightning strikes millions of trees worldwide each year, yet structured lightning damage surveys are relatively rare. Estimates drawn from the literature suggest that lightning directly or indirectly kills up to 4% of large canopy trees in a stand annually. Lightning is a major cause of death for pines in southeastern US forests and for large cacti in some deserts, but its landscape-level effects exclusive of fire at higher latitudes are poorly known. We quantified damage to trees from lightning and other sources in hemlock–hardwood forests of the Huron Mountain Region of Michigan, USA. This region receives ca. 100 cloud-to-ground lightning flashes per year, with most occurring in May to August. We recorded abiotic and biotic damage on 309 trees distributed among nine transects, each >2 km long. None of the transect trees had lightning scars, and we observed only 14 clear cases of lightning damage among thousands of trees examined during associated meander surveys (each ca. 0.5 ha). This damage was more commonly associated with emergent stature (50% of struck trees) and higher rates of biotic damage (50%) than we observed in the 309 transect trees (22% emergent status and 16% incidence of biotic damage). Nearly all (93%) of the lightning damaged trees were conifers, suggesting that either susceptibility to, or response to, lightning strikes has a phylogenetic basis. These preliminary results provide a foundation for comparative studies in other forests. Accurate quantification of lightning-induced tree mortality will improve forest turnover models and facilitate predictions of future forest structure under conditions of increased lightning frequency.
DC electrical resistivity studies and structure of Ni0.5Zn0.5CrxFe2-xO4 nanoferrites
Authors: Prasad M. Siva Ram , Rajesh Babu B. , Ramesh K. V. , Trinath K.
Published: May 2015

Chromium substituted Ni – Zn nano ferrite samples with composition Ni 0.5 Zn 0.5 Cr x⋅ Fe 2-x O 4 (x = 0.00 to 0.25 in steps of 0.05) have been prepared by autocombustion method employing citric acid as an oxidant. Structural, morphological and microstructural characterizations were done on the sintered powders at 1000°C while the DC electrical resistivity studies have been performed on the pellets sintered at the same temperature. The thermogravimetric and differential thermal analysis (TG-DTA) studies indicated the presence of broad exotherm and valley centered about temperature of 400°C. The formation of single-spinel phase has been observed for all the samples. The ionic packing coefficient, vacancy parameter and fulfillment coefficient have all been obtained for each composition. The scanning electron micrographs showed the formation of fine grains with size very less than 1 μm in all samples with a little agglomeration. The observed variation in DC electrical resistivity and activation energy with Cr 3+ substitution are attributed to the modifications in microstructure, structural defects and the influence of Cr 3+ ions with support of hopping mechanism.
A New Multidimensional Drift Flux Mixture Model for Gas–Liquid Droplet Two-Phase Flow
Authors: Shang Zhi , Lou Jing , Li Hongying
Published: May 2015

A new multidimensional drift flux mixture model was developed to simulate gas–liquid droplet two-phase flows. The new drift flux model was modified by considering the centrifugal force on the liquid-droplets. Therefore the traditional 1D drift flux model was upgraded to multidimension, 2D and 3D. The slip velocities between the continual phase (gas) and the dispersed phase (liquid droplets) were able to calculate through the multidimensional diffusion flux velocities based on the new modified drift flux model. Through the numerical simulations comparing with the experiments and the simulations of other models on the backward-facing step and the water mist spray two-phase flows, the new model was validated.
TECHNOLOGY TRANSFER MODELS BASED ON ACADEMIC SPIN-OFFS WITHIN THE INDUSTRIAL BIOTECHNOLOGY SECTOR
Authors: FESTEL GUNTER
Published: May 2015

Industrial biotechnology is the application of biotechnology for the environment friendly production and processing of chemicals, pharmaceuticals, materials, and bioenergy. The commercial development is mainly driven by multinational enterprises (MNEs), whereas small and medium enterprises (SMEs) contribute primarily to the technological development. The challenge is that generally a technology transfer gap exists between basic research and development (R&D) at universities or research institutions and the commercialisation of the results by established companies. Based on the analysis of 17 case studies from the industrial biotechnology sector, this paper investigates the technology transfer role of spin-offs from universities and research institutions to close the technology transfer gap. Different technology transfer models have been used between established companies and spin-offs after further developing the technology following the spin-off process. Whereas MNEs are very active in making new technologies available both by acquiring spin-offs or engaging them as service providers, SMEs, due to limited financial resources, are more focused on research cooperations with spin-offs, especially by engaging them as service providers.
Recursive Markov Decision Processes and Recursive Stochastic Games
Authors: Etessami Kousha , Yannakakis Mihalis
Published: May 2015

We introduce Recursive Markov Decision Processes (RMDPs) and Recursive Simple Stochastic Games (RSSGs), which are classes of (finitely presented) countable-state MDPs and zero-sum turn-based (perfect information) stochastic games. They extend standard finite-state MDPs and stochastic games with a recursion feature. We study the decidability and computational complexity of these games under termination objectives for the two players: one player's goal is to maximize the probability of termination at a given exit, while the other player's goal is to minimize this probability. In the
quantitative termination problems
, given an RMDP (or RSSG) and probability
p
, we wish to decide whether the value of such a termination game is at least
p
(or at most
p
); in the
qualitative termination problem
we wish to decide whether the value is 1. The important 1-exit subclasses of these models, 1-RMDPs and 1-RSSGs, correspond in a precise sense to controlled and game versions of classic stochastic models, including multitype Branching Processes and Stochastic Context-Free Grammars, where the objective of the players is to maximize or minimize the probability of termination (extinction).

We provide a number of upper and lower bounds for qualitative and quantitative termination problems for RMDPs and RSSGs. We show both problems are undecidable for multi-exit RMDPs, but are decidable for 1-RMDPs and 1-RSSGs. Specifically, the quantitative termination problem is decidable in PSPACE for both 1-RMDPs and 1-RSSGs, and is at least as hard as the square root sum problem, a well-known open problem in numerical computation. We show that the qualitative termination problem for 1-RMDPs (i.e., a controlled version of branching processes) can be solved in polynomial time both for maximizing and minimizing 1-RMDPs. The qualitative problem for 1-RSSGs is in NP ∩ coNP, and is at least as hard as the quantitative termination problem for Condon's finite-state simple stochastic games, whose complexity remains a well known open problem. Finally, we show that even for 1-RMDPs, more general (qualitative and quantitative) model-checking problems with respect to linear-time temporal properties are undecidable even for a fixed property.
Document Spanners
Authors: Fagin Ronald , Kimelfeld Benny , Reiss Frederick , Vansummeren Stijn
Published: May 2015

An intrinsic part of information extraction is the creation and manipulation of relations extracted from text. In this article, we develop a foundational framework where the central construct is what we call a
document spanner
(or just
spanner
for short). A spanner maps an input string into a relation over the spans (intervals specified by bounding indices) of the string. The focus of this article is on the representation of spanners. Conceptually, there are two kinds of such representations. Spanners defined in a
primitive
representation extract relations directly from the input string; those defined in an
algebra
apply algebraic operations to the primitively represented spanners. This framework is driven by SystemT, an IBM commercial product for text analysis, where the primitive representation is that of regular expressions with capture variables.

We define additional types of primitive spanner representations by means of two kinds of automata that assign spans to variables. We prove that the first kind has the same expressive power as regular expressions with capture variables; the second kind expresses precisely the algebra of the
regular
spanners—the closure of the first kind under standard relational operators. The
core
spanners extend the regular ones by string-equality selection (an extension used in SystemT). We give some fundamental results on the expressiveness of regular and core spanners. As an example, we prove that regular spanners are closed under difference (and complement), but core spanners are not. Finally, we establish connections with related notions in the literature.
The Power of Alternative Kolmogorov-Smirnov Tests Based on Transformations of the Data
Authors: Kim Song-Hee , Whitt Ward
Published: May 2015

The Kolmogorov-Smirnov (KS) statistical test is commonly used to determine if data can be regarded as a sample from a sequence of independent and identically distributed (i.i.d.) random variables with specified continuous cumulative distribution function (cdf) F, but with small samples it can have insufficient power, that is, its probability of rejecting natural alternatives can be too low. However, in 1961, Durbin showed that the power of the KS test often can be increased, for a given significance level, by a well-chosen transformation of the data. Simulation experiments reported here show that the power can often be more consistently and substantially increased by a different transformation. We first transform the given sequence to a sequence of mean-1 exponential random variables, which is equivalent to a rate-1 Poisson process. We then apply the classical conditional-uniform transformation to convert the arrival times into i.i.d. random variables uniformly distributed on [0, 1]. And then, after those two preliminary steps, we apply the original Durbin transformation. Since these KS tests assume a fully specified cdf, we also investigate the consequence of having to estimate parameters of the cdf.
Regenerative Simulation for Queueing Networks with Exponential or Heavier Tail Arrival Distributions
Authors: Moka Sarat Babu , Juneja Sandeep
Published: May 2015

Multiclass open queueing networks find wide applications in communication, computer, and fabrication networks. Steady-state performance measures associated with these networks is often a topic of interset. Conceptually, under mild conditions, a sequence of regeneration times exists in multiclass networks, making them amenable to regenerative simulation for estimating steady-state performance measures. However, typically, identification of such a sequence in these networks is difficult. A well-known exception is when all interarrival times are exponentially distributed, where the instants corresponding to customer arrivals to an empty network constitute a sequence of regeneration times. In this article, we consider networks in which the interarrival times are generally distributed but have exponential or heavier tails. We show that these distributions can be decomposed into a mixture of sums of independent random variables such that at least one of the components is exponentially distributed. This allows an easily implementable embedded sequence of regeneration times in the underlying Markov process. We show that among all such interarrival time decompositions, the one with an exponential component that has the largest mean minimizes the asymptotic variance of the standard deviation estimator. We also show that under mild conditions on the network primitives, the regenerative mean and standard deviation estimators are consistent and satisfy a joint central limit theorem useful for constructing asymptotically valid confidence intervals.
Simulating the Visual Experience of Very Bright and Very Dark Scenes
Authors: E. Jacobs David , Gallo Orazio , A. Cooper Emily , Pulli Kari , Levoy Marc
Published: May 2015

The human visual system can operate in a wide range of illumination levels due to several adaptation processes working in concert. For the most part, these adaptation mechanisms are transparent, leaving the observer unaware of his or her absolute adaptation state. At extreme illumination levels, however, some of these mechanisms produce perceivable secondary effects, or epiphenomena. In bright light, these include bleaching afterimages and adaptation afterimages, while in dark conditions these include desaturation, loss of acuity, mesopic hue shift, and the Purkinje effect. In this work we examine whether displaying these effects explicitly can be used to extend the apparent dynamic range of a conventional computer display. We present phenomenological models for each effect, describe efficient computer graphics methods for rendering our models, and propose a gaze-adaptive display that injects the effects into imagery on a standard computer monitor. Finally, we report the results of psychophysical experiments which reveal that, while mesopic epiphenomena are a strong cue that a stimulus is very dark, afterimages have little impact on the perception that a stimulus is very bright.
Taxonomy and Survey of Collaborative Intrusion Detection
Authors: Vasilomanolakis Emmanouil , Karuppayah Shankar , Mühlhäuser Max , Fischer Mathias
Published: May 2015

The dependency of our society on networked computers has become frightening: In the economy, all-digital networks have turned from facilitators to drivers; as cyber-physical systems are coming of age, computer networks are now becoming the central nervous systems of our physical world—even of highly critical infrastructures such as the power grid. At the same time, the 24/7 availability and correct functioning of networked computers has become much more threatened: The number of sophisticated and highly tailored attacks on IT systems has significantly increased. Intrusion Detection Systems (IDSs) are a key component of the corresponding defense measures; they have been extensively studied and utilized in the past. Since conventional IDSs are not scalable to big company networks and beyond, nor to massively parallel attacks, Collaborative IDSs (CIDSs) have emerged. They consist of several monitoring components that collect and exchange data. Depending on the specific CIDS architecture, central or distributed analysis components mine the gathered data to identify attacks. Resulting alerts are correlated among multiple monitors in order to create a holistic view of the network monitored. This article first determines relevant requirements for CIDSs; it then differentiates distinct building blocks as a basis for introducing a CIDS design space and for discussing it with respect to requirements. Based on this design space, attacks that evade CIDSs and attacks on the availability of the CIDSs themselves are discussed. The entire framework of requirements, building blocks, and attacks as introduced is then used for a comprehensive analysis of the state of the art in collaborative intrusion detection, including a detailed survey and comparison of specific CIDS approaches.
Automatic Production of Tailored Packaging for Fragile Archaeological Artifacts
Authors: Sánchez-Belenguer Carlos , Vendrell-Vidal Eduardo , Sánchez-López Miguel , Díaz-Marín Carmen , Aura-Castro Elvira
Published: May 2015

This article deals with storage and transportation of fragile heritage objets. The main goal is to create an ad hoc packaging software solution by combining the use of 3D scanning and 3D milling technologies. Traditionally, packaging for this kind of object is made manually, creating custom supports and boxes adapted to the specific needs and particularities of each case. This process is time consuming and fully depends on the conservator’s skills. On the other hand, the proposed solution provides a faster execution and a standard solution adapted to every object. The process starts with the acquisition of 3D digital models of the original artifacts and uses an interactive GPU-accelerated algorithm to assist the conservator in the construction of the package. The final result is a CNC program that is sent to a low-cost milling machine to produce the housing for the selected artifact. Unlike 3D printers, milling machines allow working with lots of different materials, which is a key aspect for this kind of package: chemical stability and shock absorption are mandatory. Given that during the design process original artifacts are only manipulated in the acquisition stage, risks of damaging them are also reduced. Since the whole process is considered in the same application, intermediate calculations are performed considering manufacturing and user-defined restrictions. This way, together with a GPU implementation, achieved results are very fast, providing a real-time application with visual feedback.
Computer Science (CS) Education in Indian Schools
Authors: Raman Raghu , Venkatasubramanian Smrithi , Achuthan Krishnashree , Nedungadi Prema
Published: May 2015

Computer science (CS) and its enabling technologies are at the heart of this information age, yet its adoption as a core subject by senior secondary students in Indian schools is low and has not reached critical mass. Though there have been efforts to create core curriculum standards for subjects like Physics, Chemistry, Biology, and Math, CS seems to have been kept outside the purview of such efforts leading to its marginalization. As a first step, using the Darmstadt model from the ITiCSE working group that provides a systematic categorization approach to CS education in schools, we coded and analyzed the CS situation for the Indian schools. Next, we focused on the motivation category of the Darmstadt model and investigated behavioral intentions of secondary school students and teachers from 332 schools in India. Considering the CS subject as an educational innovation, using Rogers’ Theory of Diffusion of Innovations, we propose a pedagogical framework for innovation attributes that can significantly predict-adoption of the CS subject among potential-adopter students and teachers. Data was analyzed to answer research questions about student and teacher intentions, influence of gender, school management, and school location in adopting CS. Interestingly, girls, urban students, teachers, and private schools were seen favoring the adoption of CS. An important issue that needed to be addressed, however, was the interchangeable use of terms like CS, Informatics, ICT, and digital literacy. Through our article, we offer a promising picture of the educational policy directives and the academic environment in India that is rapidly growing and embracing CS as a core subject of study in schools. We also analyze the factors that influence the adoption of CS by school students and teachers and conclude that there is a very positive response for CS among educators and students in India.
Discrete Derivatives of Vector Fields on Surfaces -- An Operator Approach
Authors: Azencot Omri , Ovsjanikov Maks , Chazal Frédéric , Ben-Chen Mirela
Published: May 2015

Vector fields on surfaces are fundamental in various applications in computer graphics and geometry processing. In many cases, in addition to representing vector fields, the need arises to compute their
derivatives
, for example, for solving partial differential equations on surfaces or for designing vector fields with prescribed smoothness properties. In this work, we consider the problem of computing the
Levi-Civita covariant derivative
, that is, the tangential component of the standard directional derivative, on triangle meshes. This problem is challenging since, formally, tangent vector fields on polygonal meshes are often viewed as being discontinuous, hence it is not obvious what a good derivative formulation would be. We leverage the relationship between the Levi-Civita covariant derivative of a vector field and the directional derivative of its component functions to provide a simple, easy-to-implement discretization for which we demonstrate experimental convergence. In addition, we introduce two linear which provide access to additional constructs in Riemannian geometry that are not easy to discretize otherwise, including the
parallel transport
operator which can be seen simply as a certain matrix exponential. Finally, we show the applicability of our operator to various tasks, such as fluid simulation on curved surfaces and vector field design, by posing algebraic constraints on the covariant derivative operator.
Real-Time Nonlinear Shape Interpolation
Authors: Von-Tycowicz Christoph , Schulz Christian , Seidel Hans-Peter , Hildebrandt Klaus
Published: May 2015

We introduce a scheme for real-time nonlinear interpolation of a set of shapes. The scheme exploits the structure of the shape interpolation problem, in particular the fact that the set of all possible interpolated shapes is a low-dimensional object in a high-dimensional shape space. The interpolated shapes are defined as the minimizers of a nonlinear objective functional on the shape space. Our approach is to construct a reduced optimization problem that approximates its unreduced counterpart and can be solved in milliseconds. To achieve this, we restrict the optimization to a low-dimensional subspace that is specifically designed for the shape interpolation problem. The construction of the subspace is based on two components: a formula for the calculation of derivatives of the interpolated shapes and a Krylov-type sequence that combines the derivatives and the Hessian of the objective functional. To make the computational cost for solving the reduced optimization problem independent of the resolution of the example shapes, we combine the dimensional reduction with schemes for the efficient approximation of the reduced nonlinear objective functional and its gradient. In our experiments, we obtain rates of 20--100 interpolated shapes per second, even for the largest examples which have 500k vertices per example shape.
Ancient Polychromy
Authors: Siotto Eliana , Callieri Marco , Dellepiane Matteo , Scopigno Roberto
Published: May 2015

Digital reconstruction of ancient polychromy is a relatively recent phenomenon in the history of archaeological and architectural heritage documentation. It has emerged as a result of new interest in the experimental archaeology and the technological development of computer graphic tools. Therefore, this article presents a project aimed at the scientific reconstruction of the original polychromy and the realistic rendering of an ancient sarcophagus, obtained with the use of some open source tools. In particular, starting from the accurate study of a polychrome Roman sarcophagus (National Roman Museum in Rome, inv. no. 125891), we show how the MeshLab tool was used to support the polychrome reconstruction stage and how Blender (or, rather, a combination of MeshLab and Blender) was used to achieve a more sophisticated visual presentation of the current and reconstruction ancient colour. A central role has been given to the rendering of different and overlapped layers of paint.
Lazarus Code
Authors: Neville-Neil George
Published: May 2015

I’ve been asked to look into the possibility of taking a 15-year-old piece of open-source software and updating it to work on a current system used by my company. The code itself doesn’t seem to be too bad, at least no worse than the code I’m used to reading, but I suspect it might be easier to write a new version from scratch than to try to understand code that I didn’t write and which no one has actively maintained for several years. What is the point at which I should decide to ignore this old code and write something new?
Massive atomics for massive parallelism on GPUs
Authors: Egielski Ian J. , Huang Jesse , Zhang Eddy Z.
Published: May 2015

One important type of parallelism exploited in many applications is reduction type parallelism. In these applications, the order of the read-modify-write updates to one shared data object can be arbitrary as long as there is an imposed order for the read-modify-write updates. The typical way to parallelize these types of applications is to first let every individual thread perform local computation and save the results in thread-private data objects, and then merge the results from all worker threads in the reduction stage. All applications that fit into the map reduce framework belong to this category. Additionally, the machine learning, data mining, numerical analysis and scientific simulation applications may also benefit from reduction type parallelism. However, the parallelization scheme via the usage of thread-private data objects may not be vi- able in massively parallel GPU applications. Because the number of concurrent threads is extremely large (at least tens of thousands of), thread-private data object creation may lead to memory space explosion problems.

In this paper, we propose a novel approach to deal with shared data object management for reduction type parallelism on GPUs. Our approach exploits fine-grained parallelism while at the same time maintaining good programmability. It is based on the usage of intrinsic hardware atomic instructions. Atomic operation may appear to be expensive since it causes thread serialization when multiple threads atomically update the same memory object at the same time. However, we discovered that, with appropriate atomic collision reduction techniques, the atomic implementation can out- perform the non-atomics implementation, even for benchmarks known to have high performance non-atomics GPU implementations. In the meantime, the usage of atomics can greatly reduce coding complexity as neither thread-private object management or explicit thread-communication (for the shared data objects protected by atomic operations) is necessary.
Allocation folding based on dominance
Authors: Clifford Daniel , Payer Hannes , Starzinger Michael , Titzer Ben L.
Published: May 2015

Memory management system performance is of increasing importance in today's managed languages. Two lingering sources of overhead are the direct costs of memory allocations and write barriers. This paper introduces it allocation folding, an optimization technique where the virtual machine automatically folds multiple memory allocation operations in optimized code together into a single, larger it allocation group. An allocation group comprises multiple objects and requires just a single bounds check in a bump-pointer style allocation, rather than a check for each individual object. More importantly, all objects allocated in a single allocation group are guaranteed to be contiguous after allocation and thus exist in the same generation, which makes it possible to statically remove write barriers for reference stores involving objects in the same allocation group. Unlike object inlining, object fusing, and object colocation, allocation folding requires no special connectivity or ownership relation between the objects in an allocation group. We present our analysis algorithm to determine when it is safe to fold allocations together and discuss our implementation in V8, an open-source, production JavaScript virtual machine. We present performance results for the Octane and Kraken benchmark suites and show that allocation folding is a strong performance improvement, even in the presence of some heap fragmentation. Additionally, we use four hand-selected benchmarks JPEGEncoder, NBody, Soft3D, and Textwriter where allocation folding has a large impact.
Geographic-Related Differences of Pituitary Adenomas Hormone Profile: Analysis of Two Groups Coming from Southeastern and Eastern Europe
Authors: Cimpean Anca Maria , Melnic Eugen , Bălinişteanu Bogdan , Corlan Ana , Coculescu Mihail , Rusu Sergiu , Raica Marius
Published: May 2015

We compared the immunoprofile of pituitary adenomas from Romania and Moldova. One hundred and eighty cases coming from Romania (94 cases, group 1) and Moldova (86 cases, group 2) were assessed by immunohistochemistry regarding all six basic hormones expressed in pituitary adenomas. Specific differences and similarities were found and stated for both groups. In group 1, 70% of cases were pituitary adenomas positive for one hormone, 13% were plurihormonal, while 17% were negative. In group 2, 50,3% of the cases expressed only one hormone and 12,5% were negative for all hormones. The highest difference was observed for plurihormonal adenomas, found in about 37,2% of cases for group 2 (2.86 times higher for group 2 compared with group 1). A higher incidence of GH-secreting adenomas characterized group “1,” while group “2” had the highest percent of LH-secreting adenomas, 55% of cases being positive. Triple association was noticed in 4.25% of cases of group 1 and in 8,13% out of total cases, from group 2. Four-hormone association was found only in group 2, noticed in 15,56% of the cases. The present paper highlights strong evidences of a particular and different immunoprofile of pituitary adenomas coming from Romania and Moldova.