bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integration of bioenergy strategies into forest management scenarios for Crown land in New Brunswick, Canada
Authors: Carle Jean-François , MacLean David A. , Erdle Thom A. , Roy Roger J. 
Published: June 2011

About 70% (110 PJ) of energy used in New Brunswick is sourced from fossil fuels, and its high cost and uncertain long-term supply have renewed interest in bioenergy production. To evaluate opportunities for sourcing bioenergy from the forest, we integrated bioenergy and timber production into a forest estate model and evaluated joint production scenarios for 3.3 million hectares of Crown land in New Brunswick over a 100-year horizon. Scenarios included maximizing timber or bioenergy production under three timing preferences (expressed as discount rates) and various combinations of harvest residues, pulpwood biomass, and willow ( Salix spp.) plantations. Under scenarios that allocated 66% of harvest residues and 30% of pulpwood to bioenergy production, maximizing discounted (8%) timber or bioenergy, respectively, generated average timber harvests of 6.51 and 6.26 Mm3·year–1 and bioenergy outputs equivalent to 30% and 32% of provincial fossil fuel consumption. Introducing 40 000 ha of willow plantations under the maximize bioenergy scenario yielded bioenergy equivalent to 41% of provincial fossil fuel consumption while maintaining the timber harvest at 6.21 Mm3·year–1. Our study demonstrates a framework for integrating bioenergy and timber production in forest management design and quantifies the significant potential for obtaining both bioenergy and timber from the forest.
Authorization recycling in hierarchical RBAC systems
Authors: Wei Qiang , Crampton Jason , Beznosov Konstantin , Ripeanu Matei 
Published: June 2011

As distributed applications increase in size and complexity, traditional authorization architectures based on a dedicated authorization server become increasingly fragile because this decision point represents a single point of failure and a performance bottleneck. Authorization caching, which enables the reuse of previous authorization decisions, is one technique that has been used to address these challenges.
This article introduces and evaluates the mechanisms for authorization “recycling” in RBAC enterprise systems. The algorithms that support these mechanisms allow making precise and approximate authorization decisions, thereby masking possible failures of the authorization server and reducing its load. We evaluate these algorithms analytically as well as using simulation and a prototype implementation. Our evaluation results demonstrate that authorization recycling can improve the performance of distributed-access control mechanisms.
Practical and efficient cryptographic enforcement of interval-based access control policies
Authors: Crampton Jason 
Published: June 2011

The enforcement of access control policies using cryptography has received considerable attention in recent years and the security of such enforcement schemes is increasingly well understood. Recent work in the area has considered the efficient enforcement of temporal and geo-spatial access control policies, and asymptotic results for the time and space complexity of efficient enforcement schemes have been obtained. However, for practical purposes, it is useful to have explicit bounds for the complexity of enforcement schemes.
In this article we consider interval-based access control policies, of which temporal and geo-spatial access control policies are special cases. We define enforcement schemes for interval-based access control policies for which it is possible, in almost all cases, to obtain exact values for the schemes' complexity, thereby subsuming a substantial body of work in the literature. Moreover, our enforcement schemes are more practical than existing schemes, in the sense that they operate in the same way as standard cryptographic enforcement schemes, unlike other efficient schemes in the literature. The main difference between our approach and earlier work is that we develop techniques that are specific to the cryptographic enforcement of interval-based access control policies, rather than applying generic techniques that give rise to complex constructions and asymptotic bounds.
Simple design; research vs. teaching; and quest to learn
Authors: Reed Daniel , Guzdial Mark , Robertson Judy 
Published: June 2011

The
Communications
Web site, http://cacm.acm.org, features more than a dozen bloggers in the BLOG@CACM community. In each issue of
Communications
, we'll publish selected posts or excerpts.

twitter

Follow us on Twitter at http://twitter.com/blogCACM
http://cacm.acm.org/blogs/blog-cacm
Daniel Reed writes about design and disruptive technologies. Mark Guzdial discusses the tension between teaching and research at U.S. universities. Judy Robertson argues in favor of educational video games in the classroom.
Closed world data exchange
Authors: Hernich André , Libkin Leonid , Schweikardt Nicole 
Published: June 2011

Data exchange deals with translating data structured in some source format into data structured in some target format, given a specification of the relationship between the source and the target and possibly constraints on the target; and answering queries over the target in a way that is semantically consistent with the information in the source. Theoretical foundations of data exchange have been actively explored recently. It was also noticed that the standard semantics for query answering in data exchange may lead to counterintuitive or anomalous answers.
In the present article, we explain that this behavior is due to the fact that solutions can contain invented information (information that is not related to the source instance), and that the presence of incomplete information in target instances has been ignored. In particular, proper query evaluation techniques for databases with nulls have not been used, and the distinction between closed and open world semantics has not been made.
We present a concept of solutions, called CWA-solutions, that is based on the closed world assumption. For data exchange settings without constraints on the target, the space of CWA-solutions has two extreme points: the canonical universal solution (the maximal CWA-solution) and the core of the universal solutions (the minimal CWA-solution), both of them well studied in data exchange. In the presence of constraints on the target, the core of the universal solutions is still the minimal CWA-solution, but there may be no unique maximal CWA-solution. We show how to define the semantics of query-answering taking into account incomplete information, and show that some of the well-known anomalies go away with the new semantics. The article also contains results on the complexity of query-answering, upper approximations to queries (maybe-answers), and various extensions.
Natural actor and belief critic
Authors: Jurčíček Filip , Thomson Blaise , Young Steve 
Published: June 2011

This article presents a novel algorithm for learning parameters in statistical dialogue systems which are modeled as Partially Observable Markov Decision Processes (POMDPs). The three main components of a POMDP dialogue manager are a dialogue model representing dialogue state information; a policy that selects the system's responses based on the inferred state; and a reward function that specifies the desired behavior of the system. Ideally both the model parameters and the policy would be designed to maximize the cumulative reward. However, while there are many techniques available for learning the optimal policy, no good ways of learning the optimal model parameters that scale to real-world dialogue systems have been found yet.
The presented algorithm, called the Natural Actor and Belief Critic (NABC), is a policy gradient method that offers a solution to this problem. Based on observed rewards, the algorithm estimates the natural gradient of the expected cumulative reward. The resulting gradient is then used to adapt both the prior distribution of the dialogue model parameters and the policy parameters. In addition, the article presents a variant of the NABC algorithm, called the Natural Belief Critic (NBC), which assumes that the policy is fixed and only the model parameters need to be estimated. The algorithms are evaluated on a spoken dialogue system in the tourist information domain. The experiments show that model parameters estimated to maximize the expected cumulative reward result in significantly improved performance compared to the baseline hand-crafted model parameters. The algorithms are also compared to optimization techniques using plain gradients and state-of-the-art random search algorithms. In all cases, the algorithms based on the natural gradient work significantly better.
From people to entities
Authors: Demartini Gianluca 
Published: June 2011

The exponential growth of digital information available in Enterprises and on the Web creates the need for search tools that can respond to the most sophisticated informational needs. Retrieving relevant documents is not enough anymore and finding entities rather than textual resources provides great support to the user both on the Web and in Enterprises. Many user tasks would be simplified if Search Engines would support typed search, and return entities instead of just Web pages. For example, an executive who tries to solve a problem needs to find people in the company who are knowledgeable about a certain topic. Aggregation of information spread over different documents is a key aspect in this process.
Finding experts is a problem mostly considered in the Enterprise setting where teams for new projects need to be built and problems need to be solved by the right persons. In the first part of the thesis, we propose a model for expert finding based on the well consolidated vector space model for Information Retrieval and investigate its effectiveness.
We can define Entity Retrieval by generalizing the expert finding problem to any entity. In Entity Retrieval the goal is to rank entities according to their relevance to a query (e.g., "Countries where I can pay in Euro"); the set of entities to be ranked is assumed to be loosely defined by a generic category, given in the query itself (e.g., countries), or by some example entities (e.g., Italy, Germany, France). In the second part of the thesis, we investigate different methods based on Semantic Web and Natural Language Processing techniques for solving these tasks both in Wikipedia and, generally, on the Web. Evaluation is a critical aspect of Information Retrieval. We contributed to the field of Information Retrieval evaluation by organizing an evaluation initiative for Entity Retrieval.
Opinions and other relevant information about entities can be provided by different sources in different contexts. News articles report about events where entities are involved. In such setting the temporal dimension is critical as news stories develop over time and new entities appear in the story and others are not relevant anymore. In the third part of this thesis, we study the problem of Entity Retrieval for news applications and the importance of the news trail history (i.e., past related articles) to determine the relevant entities in current articles. We also study opinion evolution about entities. In the last years, the blogosphere has become a vital part of the Web, covering a variety of different points of view and opinions on political and event-related topics such as immigration, election campaigns, or economic developments. We propose a method for automatically extracting public opinion about specific entities from the blogosphere.
Available online at http://www.gianlucademartini.net/research/phd/.
Combining concepts and language models for information access
Authors: Meij Edgar 
Published: June 2011

Since the middle of last century, information retrieval has gained an increasing interest. Since its inception, much research has been devoted to finding optimal ways of representingboth documents and queries, as well as improving ways of matching one with the other. In cases where document annotations or explicit semantics are available, matching algorithms can be informed using the concept languages in which such semantics are usually defined. These algorithms are able to match queries and documents based on textual and semantic evidence.
Recent advances have enabled the use of rich query representations in the form of query language models. This, in turn, allows us to account for the language associated with concepts within the retrieval model, in a principled and transparent manner. Developments in the semantic web community, such as the Linked Open Data cloud, have enabled the association of texts with concepts on a large scale. Taken together, these developments facilitate a move beyond manually assigned concepts in domain-specific contexts into the general domain.
This thesis investigates how one can improve information access by employing the actual use of concepts as measured by the language that people use when they discuss them. The main contribution is a set of models and methods that enable users to retrieve and access information on a conceptual level. Through extensive evaluations, a systematic exploration and thorough analysis of the experimental results of the proposed models is performed. Our empirical results show that a combination of top-down conceptual information and bottom-up statistical information obtains optimal performance on a variety of tasks and test collections.
The dissertation is available online at http://phdthes.is/.
Sex and Race Differences in Right Ventricular Structure and Function
Authors: Kawut Steven M. , Lima João A.C. , Barr R. Graham , Chahal Harjit , Jain Aditya , Tandri Harikrishna , Praestgaard Amy , Bagiella Emilia , Kizer Jorge R. , Johnson W. Craig , Kronmal Richard A. , Bluemke David A. 
Published: June 2011

Background—
Right ventricular (RV) morphology is an important predictor of outcomes in heart and lung disease; however, determinants of RV anatomy have not been well studied. We examined the demographic factors associated with RV morphology and function in a population-based multiethnic sample free of clinical cardiovascular disease.

Methods and Results—

In the Multi-Ethnic Study of Atherosclerosis (MESA), cardiac magnetic resonance imaging was performed on 5098 participants. Right ventricular volumes and mass were available for 4204 participants. Normative equations for RV parameters were derived with an allometric approach. The study sample (n=4123) was 61.5±10.1 years of age and 47.5% men. Older age was associated with lower RV mass (≈5% lower mass per decade), with larger age-related decrements in men than in women (
P
<0.05 for interaction). Older age was also associated with higher RV ejection fraction, an association that differed between races/ethnicities (
P
≤0.01 for interaction). Overall, men had greater RV mass (≈8%) and larger RV volumes than women, but had lower RV ejection fraction (4% in absolute terms;
P
<0.001). Blacks had lower RV mass than whites (
P
≤0.002), whereas Hispanics had higher RV mass (
P
≤0.02). When the derived normative equations were used, 7.3% (95% confidence interval, 6.5 to 8.1) met the criteria for RV hypertrophy, and 5.9% (95% confidence interval, 5.2 to 6.6) had RV dysfunction.

Conclusion—
Age, sex, and race are associated with significant differences in RV mass, RV volumes, and RV ejection fraction, potentially explaining distinct responses of the RV to cardiopulmonary disease.
Comparison of host recognition, invasion, development and reproduction of Meloidogyne graminicola and M. incognita on rice and tomato
Authors: Dutta Tushar K. , Powers Stephen J. , Kerry Brian R. , Gaur Hari S. , Curtis Rosane H.C. 
Published: June 2011

AbstractThe rice root-knot nematode Meloidogyne graminicola normally infects rice, wheat and several other graminaceous plants. Meloidogyne incognita is a serious pest of dicotyledonous crops, although it can infect and reproduce on some cereals. This paper demonstrates and compares host recognition, development and reproduction of these two species of root-knot nematodes on rice and tomato plants. Attraction bioassays in pluronic gel clearly showed that M. incognita preferred tomato roots to rice or mustard roots, whilst M. graminicola was more attracted towards rice compared with tomato or mustard roots. Based on the attraction data from this study, it can be hypothesised that either: i) the blend of attractants and repellents are different in good and poor hosts; or ii) relatively long-range attractants, together with shorter-range repellents, might affect nematode movement patterns. Some host specific attractants might also be involved. Meloidogyne incognita was able to invade and develop to adult female but did not produce eggs in rice roots. By contrast, M. graminicola developed and reproduced faster on both rice and tomato plants compared with M. incognita. Nevertheless, second-stage juveniles of both these root-knot nematodes showed a similar pattern of distribution inside the roots, preferring to accumulate at the root tips of rice or in the vascular cylinder and cortical region of tomato.
Paratylenchus conicephalus sp. n. from Iran with notes on P. similis Khan, Prasad & Mathur, 1967 (Nematoda: Paratylenchinae)
Authors: Van den Berg Esther , Eskandari Ali , Tiedt Louwrens R. , Karegar Akbar 
Published: June 2011

Abstract
During nematode surveys in Iran two Paratylenchus
populations were found. Paratylenchus conicephalus sp. n.
is described and figured from the rhizosphere of Prangos
ferulacea (L.) Lindl. and is characterised by having a 365-501
μm long body, stylet 29.5-35 μm long,
a conical lip region with four or five indistinct annuli, large submedian
lobes and four large flaps around the stoma opening, these structures
appearing as a small cap-like structure when viewed laterally with the light
microscope, four lines in the lateral field, and a sharply pointed tail
25.5-46 μm long. Paratylenchus similis is
described and figured from the rhizosphere of Artemisia
aucheri Boiss. and compared with the various descriptions of
this species.
Resistance of wheat, barley and oat to Heterodera avenae in the Pacific Northwest, USA
Authors: Smiley Richard W. , Yan Guiping , Pinkerton John N. 
Published: June 2011

Abstract
The cereal cyst nematode, Heterodera avenae, occurs in at
least seven western states of the USA and reduces grain yield in localised
regions and in selected crop management systems. Virulence phenotypes for
H. avenae populations in North America have not been
reported. Nine individual assays in six experiments were conducted to
determine the reactions of barley, oat and wheat cultivars to five
H. avenae populations in the Pacific Northwest (PNW)
states of Idaho, Oregon and Washington. Three populations were evaluated for
virulence to 23 entries of the 'International Test Assortment for
Defining Cereal Cyst Nematode Pathotypes', plus selected local
cultivars and entries representing a greater diversity of resistance genes.
The virulence phenotype(s) for populations of H. avenae in
the PNW did not correspond to any of the 11 pathotypes defined by the Test
Assortment. Five PNW populations exhibited affinities with Group 2 but were
not defined by pathotypes Ha12 and Ha22. Reproduction was prevented or
greatly inhibited by barley carrying the Rha3 resistance
gene and by most carriers of Rha2 resistance, and by
selected oat cultivars with multigenic resistance. Wheat cultivars carrying
the Cre1 resistance gene were highly effective in
suppressing H. avenae reproduction. Current PNW wheat
cultivars do not carry the Cre1 resistance gene. Crosses
between Ouyen, an Australian bread wheat with Cre1
resistance, and several PNW wheat cultivars were resistant. The
CreR gene also prevented H. avenae
reproduction in the trial where it was tested. Intermediate levels of
reproduction occurred on wheat cultivars carrying the Cre5,
Cre7 and Cre8 resistance genes, each
of which was considered useful for pyramiding into cultivars with
Cre1 resistance. This research identified genetic
resources of value in PNW cereal crop breeding programmes.
Effect of disturbances on trophic groups in soil nematode assemblages
Authors: McSorley Robert 
Published: June 2011

AbstractFree-living nematodes in soil ecosystems are vital in the decomposition of organic matter and recycling of nutrients. The effects of various types of disturbances on nematode assemblages were examined in several experiments on a single soil: a short-term detrimental disturbance from solarisation, a short-term beneficial disturbance from amendment addition, and a long-term detrimental disturbance from bare ground without plant cover. Comparison of solarised and non-solarised field plots revealed lower numbers of fungivores in solarised plots. As a result, indices involving ratios of fungivores to bacterivores and fungivores to total free-living nematodes were decreased as well. Addition of an amendment increased numbers of bacterivores. This change was also reflected in calculated indices that expressed trophic groups as percentages of the total free-living nematodes. A severely disturbed site with bare ground that was without plant cover for more than 5 years was compared with an adjacent site maintained in grass. No plant-parasitic nematodes were recovered from the bare ground site, which contained lower numbers of nematodes in all trophic groups than the grass site. However, the structure of the free-living nematode assemblages in both sites was similar, as indicated by the proportions of various trophic groups and by ratios of fungivores and bacterivores. The free-living nematode assemblage in a site with a perceived severe long-term disturbance maintained a trophic structure similar to a site with perennial plant cover.
Bursaphelenchus trypophloei sp. n. (Nematoda: Parasitaphelenchinae) – an associate of the bark beetle, Trypophloeus asperatus (Gyll.) (Coleoptera: Curculionidae, Scolytinae), in aspen, Populus tremula L.
Authors: Tomalak Marek 
Published: June 2011

Abstract
Bursaphelenchus trypophloei sp. n. is described from weakened and dead twigs of living or recently fallen aspen trees, Populus tremula, in Poland. All propagative stages of the nematode were present in larval galleries of a bark beetle, Trypophloeus asperatus, and its dauer juveniles could be found in the haemocoel of older larvae, pupae and adult beetles. Characteristic morphology of the male spicules with distinct cucullus, extended anterior vulval lip, lateral fields with four incisures, and number and arrangement of male caudal papillae indicate that B. trypophloei sp. n. is closely related to the xylophilus group. This relation has been further confirmed by DNA sequencing and phylogenetic analysis of the 28S and ITS-1 rDNA region. Bursaphelenchus trypophloei sp. n. can be separated from other species in the xylophilus group by the morphology of spicules which have a shorter capitulum and unique rostrum which is pointed somewhat anteriorly, relatively thick vulval flap, which is straight, parallel to the body long axis or bent towards the body wall at its distal end, and other morphological and morphometric characters, i.e., shape of female tail, position of excretory pore at or posterior to nerve ring, spicule length of 25.7 (23.1-28.0) μm (as measured along arc) and shape, moderate length, i.e., L = 702 (603-946) μm in females and L = 679 (543-828) μm in males, and slender body (a = 39.2 (33.0-45.2) and 40.9 (32.0-46.4) in female and male, respectively). The taxonomic separation of the new species is also confirmed by the unique molecular profile of the ITS region (ITS-RFLP). Full reproductive incompatibility of B. trypophloei sp. n. with B. xylophilus, B. mucronatus, B. fraudulentus, B. populi and B. doui has been demonstrated in in vitro diallelic cross-breeding. The newly described nematode revealed limited ability to develop and reproduce on Botrytis cinerea cultures although it produced large populations on laboratory cultures of Cytospora chrysosperma – a fungus naturally associated with galleries of the nematode vector, T. asperatus.