bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling and stability analysis of hybrid multiple access in the IEEE 802.15.4 protocol
Authors: Park Pangun , Fischione Carlo , Johansson Karl Henrik
Published: April 2013

To offer flexible quality of service to several classes of applications, the medium access control (MAC) protocol of IEEE 802.15.4 wireless sensor networks (WSNs) combines the advantages of a random access with contention with a time division multiple access (TDMA) without contention. Understanding reliability, delay, and throughput is essential to characterizing the fundamental limitations of the MAC and optimizing its parameters. Nevertheless, there is not yet a clear investigation of the achievable performance of hybrid MAC. In this article, an analytical framework for modeling the behavior of the hybrid MAC protocol of the IEEE 802.15.4 standard is proposed. The main challenge for an accurate analysis is the coexistence of the stochastic behavior of the random access and the deterministic behavior of the TDMA scheme. The analysis is done in three steps. First, the contention access scheme of the IEEE 802.15.4 exponential back-off process is modeled through an extended Markov chain that takes into account channel, retry limits, acknowledgements, unsaturated traffic, and superframe period. Second, the behavior of the TDMA access scheme is modeled by another Markov chain. Finally, the two chains are coupled to obtain a complete model of the hybrid MAC. By using this model, the network performance in terms of reliability, average packet delay, average queuing delay, and throughput is evaluated through both theoretical analysis and experiments. The protocol has been implemented and evaluated on a testbed with off-the-shelf wireless sensor devices to demonstrate the utility of the analysis in a practical setup. It is established that the probability density function of the number of received packets per superframe follows a Poisson distribution. It is determined under which conditions the guaranteed time slot allocation mechanism of IEEE 802.15.4 is stable. It is shown that the mutual effect between throughput of the random access and the TDMA scheme for a fixed superframe length is critical to maximizing the overall throughput of the hybrid MAC. In high traffic load, the throughput of the random access mechanism dominates over TDMA due to the constrained use of TDMA in the standard. Furthermore, it is shown that the effect of imperfect channels and carrier sensing on system performance heavily depends on the traffic load and limited range of the protocol parameters. Finally, it is argued that the traffic generation model established in this article may be used to design an activation timer mechanism in a modified version of the CSMA/CA algorithm that guarantees a stable network performance.
Fusion-based volcanic earthquake detection and timing in wireless sensor networks
Authors: Tan Rui , Xing Guoliang , Chen Jinzhu , Song Wen-Zhan , Huang Renjie
Published: April 2013

Volcano monitoring is of great interest to public safety and scientific explorations. However, traditional volcanic instrumentation such as broadband seismometers are expensive, power hungry, bulky, and difficult to install. Wireless sensor networks (WSNs) offer the potential to monitor volcanoes on unprecedented spatial and temporal scales. However, current volcanic WSN systems often yield poor monitoring quality due to the limited sensing capability of low-cost sensors and unpredictable dynamics of volcanic activities. In this article, we propose a novel quality-driven approach to achieving real-time, distributed, and long-lived volcanic earthquake detection and timing. By employing novel in-network collaborative signal processing algorithms, our approach can meet stringent requirements on sensing quality (i.e., low false alarm/missing rate, short detection delay, and precise earthquake onset time) at low power consumption. We have implemented our algorithms in TinyOS and conducted extensive evaluation on a testbed of 24 TelosB motes as well as simulations based on real data traces collected during 5.5 months on an active volcano. We show that our approach yields near-zero false alarm/missing rate, less than one second of detection delay, and millisecond precision earthquake onset time while achieving up to six-fold energy reduction over the current data collection approach.
Mapping hidden water pipelines using a mobile sensor droplet
Authors: Lai Ted Tsung-Te , Chen Wei-Ju , Chen Yu-Han Tiffany , Huang Polly , Chu Hao-Hau
Published: April 2013

This study presents several extensions to our previous work on the PipeProbe system, a mobile sensor system for identifying the spatial topology of hidden water pipelines (i.e., non-moldable pipes such as copper and PVC) behind walls or under floors [Lai et al. 2010]. The PipeProbe system works by dropping a tiny wireless sensor capsule into the source of a water pipeline. As the PipeProbe capsule traverses the pipelines, it gathers and transmits pressure and angular velocity readings. Through spatiotemporal analysis of these sensor readings, the proposed algorithm locates all turning points in the pipelines and maps their 3D spatial topology. This study expands upon previous research by developing new sensing techniques that identify variable-diameter pipes and differentiate 90-degree pipe turns from 45-degree pipe bends.
Energy-efficient localization
Authors: Jurdak Raja , Corke Peter , Cotillon Alban , Dharman Dhinesh , Crossman Chris , Salagnac Guillaume
Published: April 2013

GPS is a commonly used and convenient technology for determining absolute position in outdoor environments, but its high power consumption leads to rapid battery depletion in mobile devices. An obvious solution is to duty cycle the GPS module, which prolongs the device lifetime at the cost of increased position uncertainty while the GPS is off. This article addresses the trade-off between energy consumption and localization performance in a mobile sensor network application. The focus is on augmenting GPS location with more energy-efficient location sensors to bound position estimate uncertainty while GPS is off. Empirical GPS and radio contact data from a large-scale animal tracking deployment is used to model node mobility, radio performance, and GPS. Because GPS takes a considerable, and variable, time after powering up before it delivers a good position measurement, we model the GPS behavior through empirical measurements of two GPS modules. These models are then used to explore duty cycling strategies for maintaining position uncertainty within specified bounds. We then explore the benefits of using short-range radio contact logging alongside GPS as an energy-inexpensive means of lowering uncertainty while the GPS is off, and we propose strategies that use RSSI ranging and GPS back-offs to further reduce energy consumption. Results show that our combined strategies can cut node energy consumption by one third while still meeting application-specific positioning criteria.
Robust localization against outliers in wireless sensor networks
Authors: Xiao Qingjun , Bu Kai , Wang Zhijun , Xiao Bin
Published: April 2013

In wireless sensor networks, a critical system service is the localization service that determines the locations of geographically distributed sensor nodes. The raw data used by this service are the distance measurements between neighboring nodes and the position knowledge of anchor nodes. However, these raw data may contain outliers that strongly deviate from their true values, which include both the outlier distances and the outlier anchors. These outliers can severely degrade the accuracy of the localization service. Therefore, we need a robust localization algorithm that can reject these outliers. Previous studies in this field mainly focus on enhancing multilateration with outlier rejection ability, since multilateration is a primitive operation used by localization service. But patch merging, a powerful operation for increasing the percentage of localizable nodes in sparse networks, is almost neglected. We thus propose a robust patch merging operation that can reject outliers for both multilateration and patch merging. Based on this operation, we further propose a robust network localization algorithm called
RobustLoc
. This algorithm makes two major contributions. (1) RobustLoc can achieve a high percentage of localizable nodes in both dense and sparse networks. In contrast, previous methods based on robust multilateration almost always fail in sparse networks with average degrees between 5 and 7. Our experiments show that RobustLoc can localize about 90% of nodes in a sparse network with 5.5 degrees. (2) As far as we know, RobustLoc is the first to uncover the differences between outlier distances and outlier anchors. Our simulations show that RobustLoc can reject colluding outlier anchors reliably in both convex and concave networks.
Beyond triangle inequality
Authors: Yang Zheng , Jian Lirong , Wu Chenshu , Liu Yunhao
Published: April 2013

Knowing accurate positions of nodes in wireless ad hoc and sensor networks is essential for a wide range of pervasive and mobile applications. However, errors are inevitable in distance measurements and we observe that a small number of outliers can degrade localization accuracy drastically. To deal with noisy and outlier ranging results, triangle inequality, is often employed in existing approaches. Our study shows that triangle inequality has many limitations, which make it far from accurate and reliable. In this study, we formally define the outlier detection problem for network localization and build a theoretical foundation to identify outliers based on graph embeddability and rigidity theory. Our analysis shows that the redundancy of distance measurements plays an important role. We then design a bilateration generic cycles-based outlier detection algorithm, and examine its effectiveness and efficiency through a network prototype implementation of MicaZ motes as well as extensive simulations. The results show that our design significantly improves the localization accuracy by wisely rejecting outliers.
Tones for real
Authors: Syed Affan A. , Heidemann John , Ye Wei
Published: April 2013

The principles of sensor networks—low-power, wireless, in-situ sensing with many inexpensive sensors—are only recently penetrating into underwater research. Acoustic communication is best suited for underwater communication, with much lower attenuation than RF, but acoustic propagation is five orders-of-magnitude slower than RF, so propagation times stretch to hundreds of milliseconds. Low-power wakeup tones are present in new underwater acoustic modems, and when added to applications and MAC protocols they reduce energy consumption wasted on idle listening. Unfortunately, underwater acoustic tones suffer from
self-multipath
—echoes unique to the latency that can completely defeat their protocol advantages. We introduce
Self-Reflection Tone Learning
(SRTL), a novel approach where nodes use Bayesian techniques to address interference by learning to discriminate self-reflections from noise and independent communication. We present detailed experiments using an acoustic modem in controlled and uncontrolled, in-air and underwater environments. These experiments demonstrate that SRTL's knowledge corresponds to physical-world predictions, that it can cope with underwater noise and reasonable levels of artificial noise, and that it can track a changing multipath environment. Simulations confirm that these real-world experiments generalize over a wide range of conditions.
ConMem
Authors: Zhang Wei , Sun Chong , Lim Junghee , Lu Shan , Reps Thomas
Published: April 2013

Multicore technology is making concurrent programs increasingly pervasive. Unfortunately, it is difficult to deliver reliable concurrent programs, because of the huge and nondeterministic interleaving space. In reality, without the resources to thoroughly check the interleaving space, critical concurrency bugs can slip into production versions and cause failures in the field. Approaches to making the best use of the limited resources and exposing severe concurrency bugs before software release would be desirable.

Unlike previous work that focuses on bugs caused by specific interleavings (e.g., races and atomicity violations), this article targets concurrency bugs that result in one type of severe effect: program crashes. Our study of the error-propagation process of real-world concurrency bugs reveals a common pattern (50% in our nondeadlock concurrency bug set) that is highly correlated with program crashes. We call this pattern concurrency-memory bugs: buggy interleavings directly cause memory bugs (NULL-pointer-dereferences, dangling-pointers, buffer-overflows, uninitialized-reads) on shared memory objects.

Guided by this study, we built ConMem to monitor program execution, analyze memory accesses and synchronizations, and predictively detect these common and severe concurrency-memory bugs. We also built a validator,ConMem-v, to automatically prune false positives by enforcing potential bug-triggering interleavings.

We evaluated ConMem using 7 open-source programs with 10 real-world concurrency bugs. ConMem detects more tested bugs (9 out of 10 bugs) than a lock-set-based race detector and an unserializable-interleaving detector, which detect 4 and 6 bugs, respectively, with a false-positive rate about one tenth of the compared tools. ConMem-v further prunes out all the false positives. ConMem has reasonable overhead suitable for development usage.
Automated Comparison of State-Based Software Models in Terms of Their Language and Structure
Authors: Walkinshaw Neil , Bogdanov Kirill
Published: April 2013

State machines capture the sequential behavior of software systems. Their intuitive visual notation, along with a range of powerful verification and testing techniques render them an important part of the model-driven software engineering process. There are several situations that require the ability to identify and quantify the differences between two state machines (e.g. to evaluate the accuracy of state machine inference techniques is measured by the similarity of a reverse-engineered model to its reference model). State machines can be compared from two complementary perspectives: (1) In terms of theirlanguage-- the externally observable sequences of events that are permitted or not, and (2) in terms of theirstructure-- the actual states and transitions that govern the behavior. This article describes two techniques to compare models in terms of these two perspectives. It shows how the difference can be quantified and measured by adapting existing binary classification performance measures for the purpose. The approaches have been implemented by the authors, and the implementation is openly available. Feasibility is demonstrated via a case study to compare two real state machine inference approaches. Scalability and accuracy are assessed experimentally with respect to a large collection of randomly synthesized models.
Adaptive Connection Strength Models for Relationship-Based Entity Resolution
Authors: Nuray-Turan Rabia , Kalashnikov Dmitri V. , Mehrotra Sharad
Published: April 2013

Entity Resolution
(ER) is a data quality challenge that deals with ambiguous references in data and whose task is to identify all references that co-refer. Due to practical significance of the ER problem, many creative ER techniques have been proposed in the past, including those that analyze relationships that exist among entities in data. Such approaches view the database as an entity-relationship graph, where direct and indirect relationships correspond to paths in the graph. These techniques rely on measuring the
connection strength
among various nodes in the graph by using a connection strength (CS) model. While such approaches have demonstrated significant advantage over traditional ER techniques, currently they also have a significant limitation: the CS models that they use are intuition-based fixed models that tend to behave well in general, but are very generic and not tuned to a specific domain, leading to suboptimal result quality. Hence, in this article we propose an approach that employs supervised learning to adapt the connection strength measure to the given domain using the available past/training data. The adaptive approach has several advantages: it increases both the quality and efficiency of ER and it also minimizes the domain analyst participation needed to tune the CS model to the given domain. The extensive empirical evaluation demonstrates that the proposed approach reaches up to 8% higher accuracy than the graph-based ER methods that use fixed and intuition-based CS models.
A Graduate-Level Course on Entity Resolution and Information Quality
Authors: Zhou Yinle , Nelson Eric , Kobayashi Fumiko , Talburt John R.
Published: April 2013

This article discusses the topics, approaches, and lessons learned in teaching a graduate-level course covering entity resolution (ER) and its relationship to information quality (IQ). The course surveys a broad spectrum of ER topics and activities including entity reference extraction, entity reference preparation, entity reference resolution techniques, entity identity management, and entity relationship analysis. The course content also attempts to balance aspects of ER theory with practical application through a series of laboratory exercises coordinated with the lecture topics. As an additional teaching aid, a configurable, open-source entity resolution engine (OYSTER) was developed that allows students to experience with different types of ER architectures including merge-purge, record linking, identity resolution, and identity capture.
Research directions in agent communication
Authors: Chopra Amit K. , Artikis Alexander , Bentahar Jamal , Colombetti Marco , Dignum Frank , Fornara Nicoletta , Jones Andrew J. I. , Singh Munindar P. , Yolum Pinar
Published: April 2013

Increasingly, software engineering involvesopensystems consisting of autonomous and heterogeneous participants oragentswho carry out loosely coupled interactions. Accordingly, understanding and specifying communications among agents is a key concern. A focus on ways to formalizemeaningdistinguishes agent communication from traditional distributed computing: meaning provides a basis for flexible interactions and compliance checking.

Over the years, a number of approaches have emerged with some essential and some irrelevant distinctions drawn among them. As agent abstractions gain increasing traction in the software engineering of open systems, it is important to resolve the irrelevant and highlight the essential distinctions, so that future research can be focused in the most productive directions.

This article is an outcome of extensive discussions among agent communication researchers, aimed at taking stock of the field and at developing, criticizing, and refining their positions on specific approaches and future challenges. This article serves some important purposes, including identifying (1) points of broad consensus; (2) points where substantive differences remain; and (3) interesting directions of future work.
Formalizing and verifying protocol refinements
Authors: Gerard Scott N. , Singh Munindar P.
Published: April 2013

A (business) protocol describes, in high-level terms, a pattern of communication between two or more participants, specifically via the creation and manipulation of the commitments between them. In this manner, a protocol offers both flexibility and rigor: a participant may communicate in any way it chooses as long as it discharges all of its activated commitments. Protocols thus promise benefits in engineering cross-organizational business processes. However, software engineering using protocols presupposes a formalization of protocols and a notion of the
refinement
of one protocol by another. Refinement for protocols is both intuitively obvious (e.g.,
PayViaCheck
is clearly a kind of
Pay
) and technically nontrivial (e.g., compared to
Pay
,
PayViaCheck
involves different participants exchanging different messages). This article formalizes protocols and their refinement. It develops Proton, an analysis tool for protocol specifications that overlays a model checker to compute whether one protocol refines another with respect to a stated mapping. Proton and its underlying theory are evaluated by formalizing several protocols from the literature and verifying all and only the expected refinements.
A framework for trust modeling in multiagent electronic marketplaces with buying advisors to consider varying seller behavior and the limiting of seller bids
Authors: Zhang Jie , Cohen Robin
Published: April 2013

In this article, we present a framework of use in electronic marketplaces that allows buying agents to model the trustworthiness of selling agents in an effective way, making use of seller ratings provided by other buying agents known as advisors. The trustworthiness of the advisors is also modeled, using an approach that combines both personal and public knowledge and allows the relative weighting to be adjusted over time. Through a series of experiments that simulate e-marketplaces, including ones where sellers may vary their behavior over time, we are able to demonstrate that our proposed framework delivers effective seller recommendations to buyers, resulting in important buyer profit. We also propose limiting seller bids as a method for promoting seller honesty, thus facilitating successful selection of sellers by buyers, and demonstrate the value of this approach through experimental results. Overall, this research is focused on the technological aspects of electronic commerce and specifically on technology that would be used to manage trust.
Building and using social structures
Authors: Erriquez Elisabetta , Hoek Wiebe van der , Wooldridge Michael
Published: April 2013

This article investigates the conjecture that agents who make decisions in scenarios where trust is important can benefit from the use of a
social structure
, representing the social relationships that exist between agents. We propose techniques that can be used by agents to initially build and then progressively update such a structure in the light of experience. We describe an implementation of our techniques in the domain of the Agent ART testbed: we take two existing agents for this domain (“Simplet” and “Connected”) and compare their performance with versions that use our social structure (“SocialSimplet” and “SocialConnected”). We show that SocialSimplet and SocialConnected outperform their counterparts with respect to the quality of the interactions, the number of rounds won in a competition, and the total utility gained.
From manifesta to krypta
Authors: Falcone Rino , Piunti Michele , Venanzi Matteo , Castelfranchi Cristiano
Published: April 2013

In this article we consider the special abilities needed by agents for assessing trust based on inference and reasoning. We analyze the case in which it is possible to infer trust towards unknown counterparts by reasoning on abstract classes or categories of agents shaped in a concrete application domain. We present a scenario of interacting agents providing a computational model implementing different strategies to assess trust. Assuming a medical domain, categories, including both competencies and dispositions of possible trustees, are exploited to infer trust towards possibly unknown counterparts. The proposed approach for the cognitive assessment of trust relies on agents' abilities to analyze heterogeneous information sources along different dimensions. Trust is inferred based on specific observable properties (manifesta), namely explicitly readable signals indicating internal features (krypta) regulating agents' behavior and effectiveness on specific tasks. Simulative experiments evaluate the performance of trusting agents adopting different strategies to delegate tasks to possibly unknown trustees, while experimental results show the relevance of this kind of cognitive ability in the case of open multiagent systems.
Tractable POMDP representations for intelligent tutoring systems
Authors: Folsom-Kovarik Jeremiah T. , Sukthankar Gita , Schatz Sae
Published: April 2013

With Partially Observable Markov Decision Processes (POMDPs), Intelligent Tutoring Systems (ITSs) can model individual learners from limited evidence and plan ahead despite uncertainty. However, POMDPs need appropriate representations to become tractable in ITSs that model many learner features, such as mastery of individual skills or the presence of specific misconceptions. This article describes two POMDP representations—
state queues
and
observation chains
—that take advantage of ITS task properties and let POMDPs scale to represent over 100 independent learner features. A real-world military training problem is given as one example. A human study (
n
= 14) provides initial validation for the model construction. Finally, evaluating the experimental representations with simulated students helps predict their impact on ITS performance. The compressed representations can model a wide range of simulated problems with instructional efficacy equal to lossless representations. With improved tractability, POMDP ITSs can accommodate more numerous or more detailed learner states and inputs.
LONET
Authors: Yen Neil Y. , Shih Timothy K. , Jin Qun
Published: April 2013

Sharing resources and information on the Internet has become an important activity for education. In distance learning, instructors can benefit from resources, also known as Learning Objects (LOs), to create plenteous materials for specific learning purposes. Our repository (called the MINE Registry) has been developed for storing and sharing learning objects, around 22,000 in total, in the past few years. To enhance reusability, one significant concept named Reusability Tree was implemented to trace the process of changes. Also, weighting and ranking metrics have been proposed to enhance the searchability in the repository. Following the successful implementation, this study goes further to investigate the relationships between LOs from a perspective of social networks. The LONET (Learning Object Network), as an extension of Reusability Tree, is newly proposed and constructed to clarify the vague reuse scenario in the past, and to summarize collaborative intelligence through past interactive usage experiences. We define a social structure in our repository based on past usage experiences from instructors, by proposing a set of metrics to evaluate the interdependency such as prerequisites and references. The structure identifies usage experiences and can be graphed in terms of implicit and explicit relations among learning objects. As a practical contribution, an adaptive algorithm is proposed to mine the social structure in our repository. The algorithm generates adaptive routes, based on past usage experiences, by computing possible interactive input, such as search criteria and feedback from instructors, and assists them in generating specific lectures.
Personalized reading support for second-language web documents
Authors: Ehara Yo , Shimizu Nobuyuki , Ninomiya Takashi , Nakagawa Hiroshi
Published: April 2013

A novel intelligent interface eases the browsing of Web documents written in the second languages of users. It automatically predicts words unfamiliar to the user by a collective intelligence method and glosses them with their meaning in advance. If the prediction succeeds, the user does not need to consult a dictionary; even if it fails, the user can correct the prediction. The correction data are collected and used to improve the accuracy of further predictions. The prediction is personalized in that every user's language ability is estimated by a state-of-the-art language testing model, which is trained in a practical response time with only a small sacrifice of prediction accuracy. The system was evaluated in terms of prediction accuracy and reading simulation. The reading simulation results show that this system can reduce the number of clicks for most readers with insufficient vocabulary to read documents and can significantly reduce the remaining number of unfamiliar words after the prediction and glossing for all users.
A parts-based approach for automatic 3D shape categorization using belief functions
Authors: Tabia Hedi , Daoudi Mohamed , Vandeborre Jean-Philippe , Colot Olivier
Published: April 2013

Grouping 3D objects into (semantically) meaningful categories is a challenging and important problem in 3D mining and shape processing. Here, we present a novel approach to categorize 3D objects. The method described in this article, is a belief-function-based approach and consists of two stages: the training stage, where 3D objects in the same category are processed and a set of representative parts is constructed, and the labeling stage, where unknown objects are categorized. The experimental results obtained on the Tosca-Sumner and the Shrec07 datasets show that the system efficiently performs in categorizing 3D models.
Learning image-to-class distance metric for image classification
Authors: Wang Zhengxiang , Hu Yiqun , Chia Liang-Tien
Published: April 2013

Image-To-Class (I2C) distance is a novel distance used for image classification and has successfully handled datasets with large intra-class variances. However, it uses Euclidean distance for measuring the distance between local features in different classes, which may not be the optimal distance metric in real image classification problems. In this article, we propose a distance metric learning method to improve the performance of I2C distance by learning per-class Mahalanobis metrics in a large margin framework. Our I2C distance is adaptive to different classes by combining with the learned metric for each class. These multiple per-class metrics are learned simultaneously by forming a convex optimization problem with the constraints that the I2C distance from each training image to its belonging class should be less than the distances to other classes by a large margin. A subgradient descent method is applied to efficiently solve this optimization problem. For efficiency and scalability to large-scale problems, we also show how to simplify the method to learn a diagonal matrix for each class. We show in experiments that our learned Mahalanobis I2C distance can significantly outperform the original Euclidean I2C distance as well as other distance metric learning methods in several prevalent image datasets, and our simplified diagonal matrices can preserve the performance but significantly speed up the metric learning procedure for large-scale datasets. We also show in experiment that our method is able to correct the class imbalance problem, which usually leads the NN-based methods toward classes containing more training images.
An experimental evaluation of IP4-IPV6 IVI translation
Authors: Tsetse Anthony K. , Wijesinha Alexander L. , Karne Ramesh , Loukili Alae , Appiah-Kubi Patrick
Published: April 2013

While IPv6 deployment in the Internet continues to grow slowly at present, the imminent exhaustion of IPv4 addresses will encourage its increased use over the next several years. However, due to the predominance of IPv4 in the Internet, the transition to IPv6 is likely to take a long time. During the transition period, translation mechanisms will enable IPv6 hosts and IPv4 hosts to communicate with each other. For example, translation can be used when a server or application works with IPv4 but not with IPv6, and the effort or cost to modify the code is large. Stateless and stateful translation is the subject of several recent IETF RFCs. We evaluate performance of the new IVI translator, which is viewed as a design for stateless translation by conducting experiments in both LAN and Internet environments using a freely available Linux implementation of IVI. To study the impact of operating system overhead on IVI translation, we implemented the IVI translator on a bare PC that runs applications without an operating system or kernel. Our results based on internal timings in each system show that translating IPv4 packets into IPv6 packets is more expensive than the reverse, and that address mapping is the most expensive IVI operation. We also measured packets per second in the LAN, roundtrip times in the LAN and Internet, IVI overhead for various prefix sizes, TCP connection time, and the delay and throughput over the Internet for various files sizes. While both the Linux and bare PC implementations of IVI have low overhead, a modest performance gain is obtained due to using a bare PC.
Loss of Cftr function exacerbates the phenotype of Na+ hyperabsorption in murine airways
Authors: Livraghi-Butrico Alessandra , Kelly Elizabeth J. , Wilkinson Kristen J. , Rogers Troy D. , Gilmore Rodney C. , Harkema Jack R. , Randell Scott H. , Boucher Richard C. , O'Neal Wanda K. , Grubb Barbara R.
Published: April 2013

Airway surface hydration depends on the balance between transepithelial Na+ absorption and Cl− secretion. In adult mice, absence of functional cystic fibrosis transmembrane conductance regulator (Cftr) fails to recapitulate human cystic fibrosis (CF) lung disease. In contrast, overexpression of the epithelial Na+ channel β subunit in transgenic mice (βENaC-Tg) produces unregulated Na+ hyperabsorption and results in CF-like airway surface dehydration, mucus obstruction, inflammation, and increased neonatal mortality. To investigate whether the combination of airway Na+ hyperabsorption and absent Cftr-mediated Cl− secretion resulted in more severe lung pathology, we generated double-mutant ΔF508 CF/βENaC-Tg mice. Survival of ΔF508 CF/βENaC-Tg mice was reduced compared with βENaC-Tg or ΔF508 CF mice. Absence of functional Cftr did not affect endogenous or transgenic ENaC currents but produced reduced basal components of Cl− secretion and tracheal cartilaginous defects in both ΔF508 CF and ΔF508 CF/βENaC-Tg mice. Neonatal ΔF508 CF/βENaC-Tg mice exhibited higher neutrophilic pulmonary inflammation and club cell (Clara cell) necrosis compared with βENaC-Tg littermates. Neonatal ΔF508 CF/βENaC-Tg mice also exhibited spontaneous bacterial infections, but the bacterial burden was similar to that of βENaC-Tg littermates. Adult ΔF508 CF/βENaC-Tg mice exhibited pathological changes associated with eosinophilic crystalline pneumonia, a phenotype not observed in age-matched βENaC-Tg mice. Collectively, these data suggest that the combined abnormalities in Na+ absorption and Cl− secretion produce more severe lung disease than either defect alone. Airway cartilage abnormalities, airway cell necrosis, and exaggerated neutrophil infiltration likely interact with defective mucus clearance caused by βENaC overexpression and absent CFTR-mediated Cl− secretion to produce the increased neonatal mortality observed in ΔF508 CF/βENaC-Tg mice.
Leukocytosis of Unknown Origin: Gangrenous Cholecystitis
Authors: Nidimusili Amara Jyothi , Alraies M. Chadi , Eisa Naseem , Alraiyes Abdul Hamid , Shaheen Khaldoon
Published: April 2013

There have been case reports where patients admitted with acute cholecystitis, who were managed conservatively, had subsequently developed GC (gangrenous cholecystitis). The current case is unique, since our patient denied any prior episodes of abdominal pain and the only tip off was leukocytosis. A high index of suspicion is essential for the early diagnosis and treatment of GC. GC has a mortality rate of up to 22% and a complication rate of 16–25%. Complications associated with GC include perforation, which has been reported to occur in as many as 10% of cases of acute cholecystitis. The radiological investigations may not be conclusive. Ultrasonography usually serves as the first-line imaging modality for the evaluation of patients with clinically suspected acute cholecystitis. However, CT can play an important role in the evaluation of these patients if sonography is inconclusive. There is a need for an early (if not urgent) surgical intervention in acute cholecystitis (whether laparoscopic or open surgery) in order to decrease the time elapsed from the start of symptoms to admission and treatment.
Association Between Physician Follow-Up and Outcomes of Care After Chest Pain Assessment in High-Risk Patients
Authors: Czarnecki Andrew , Chong Alice , Lee Douglas S. , Schull Michael J. , Tu Jack V. , Lau Ching , Farkouh Michael E. , Ko Dennis T.
Published: April 2013

Background—

Assessment of chest pain is one of the most common reasons for emergency department visits in developed countries. Although guidelines recommend primary care physician (PCP) follow-up for patients who are subsequently discharged, little is known about the relationship between physician follow-up and clinical outcomes.

Methods and Results—

An observational study was conducted on patients with higher baseline risk, defined as having diabetes mellitus or established cardiovascular disease, who were evaluated for chest pain, discharged, and without adverse clinical outcomes for 30 days in Ontario from 2004 to 2010. Multivariable proportional hazard models were constructed to adjust for potential confounding between physician groups (cardiologist, PCP, or none). Among 56767 included patients, 17% were evaluated by cardiologists, 58% were evaluated by PCPs alone, and 25% had no physician follow-up. The mean age was 66±15 years, and 53% were male. The highest rates of diagnostic testing, medical therapy, and coronary revascularization were seen among patients treated by cardiologists. At 1 year, the rate of death or MI was 5.5% (95% confidence interval, 5.0–5.9) in the cardiology group, 7.7% (95% confidence interval, 7.4–7.9) in the PCP group, and 8.6% (95% confidence interval, 8.2–9.1) in the no-physician group. After adjustment, cardiologist follow-up was associated with significantly lower adjusted hazard ratio of death or MI compared with PCP (hazard ratio, 0.85; 95% confidence interval, 0.78–0.92) and no physician (hazard ratio, 0.79; 95% confidence interval, 0.71–0.88) follow-up.

Conclusions—

Among patients with higher baseline cardiovascular risk who were discharged from the emergency department after evaluation for chest pain in Ontario, follow-up with a cardiologist was associated with a decreased risk of all-cause mortality or hospitalization for MI at 1 year compared with follow-up with a PCP or no physician follow-up.
Effect of Race and Ethnicity on Outcomes With Drug-Eluting and Bare Metal Stents
Authors: Kumar Robert S. , Douglas Pamela S. , Peterson Eric D. , Anstrom Kevin J. , Dai David , Brennan J. Matthew , Hui Peter Y.M. , Booth Michael E. , Messenger John C. , Shaw Richard E.
Published: April 2013

Background—

Black, Hispanic, and Asian patients have been underrepresented in percutaneous coronary intervention clinical trials; therefore, there are limited data available on outcomes for these race/ethnicity groups.

Methods and Results—

We examined outcomes in 423 965 patients in the National Cardiovascular Data Registry CathPCI Registry database linked to Medicare claims for follow-up. Within each race/ethnicity group, we examined trends in drug-eluting stent (DES) use, 30-month outcomes, and relative outcomes of DES versus bare metal stents. Overall, 390 351 white, 20 191 black, 9342 Hispanic, and 4171 Asian patients > 65 years of age underwent stent implantation from 2004 through 2008 at 940 National Cardiovascular Data Registry participating sites. Trends in adoption of DES were similar across all groups. Relative to whites, black and Hispanic patients undergoing percutaneous coronary intervention had higher long-term risks of death and myocardial infarction (blacks: hazard ratio, 1.28; 95% confidence interval, 1.24–1.32; Hispanics: hazard ratio, 1.15; 95% confidence interval, 1.10–1.21). Long-term outcomes were similar in Asians and whites (hazard ratio, 0.99; 95% confidence interval, 0.92–1.08). Use of DES was associated with better 30-month survival and lower myocardial infarction rates compared with the use of bare metal stents among all race/ethnicity groups except Hispanics, who had similar outcomes with DES or bare metal stents.

Conclusions—

Black and Hispanic patients undergoing percutaneous coronary intervention had worse long-term outcomes relative to white and Asian patients. Compared with bare metal stent use, DES use was generally associated with superior long-term outcomes in all racial and ethnic groups, although these differences were not statistically significant in Hispanic patients.
Status of Cardiovascular Health in US Adolescents
Authors: Shay Christina M. , Ning Hongyan , Daniels Stephen R. , Rooks Cherie R. , Gidding Samuel S. , Lloyd-Jones Donald M.
Published: April 2013

Background—

The American Heart Association recently developed definitions and metrics for monitoring the spectrum of cardiovascular health in adolescents and children. Current nationally representative prevalence estimates according to sex and race/ethnicity are unavailable.

Methods and Results—

We examined the components of cardiovascular health in 4673 participants aged 12 to 19 years (representing ≈33.2 million US adolescents) from the 2005–2010 National Health and Nutrition Examination Surveys. Population prevalence of individual cardiovascular health behaviors and factors was estimated according to American Heart Association criteria for poor, intermediate, and ideal levels. Ideal blood pressure was most prevalent (males, 78%; females, 90%), whereas a dramatically low prevalence of ideal Healthy Diet Score was observed (males, <1%; females, <1%). Females exhibited a lower prevalence of ideal total cholesterol (65% versus 72%, respectively) and ideal physical activity levels (44% versus 67%, respectively) yet a higher prevalence of ideal blood glucose (89% versus 74%, respectively) compared with males. Approximately two thirds of adolescents exhibited ideal body mass index (males, 66%; females, 67%) and ideal smoking status (males, 66%; females, 70%). Less than 50% of adolescents exhibited ≥5 ideal cardiovascular health components (45%, males; 50%, females). Prevalence estimates according to sex were consistent across race/ethnic groups.

Conclusions—

The low prevalence of ideal cardiovascular health behaviors in US adolescents, particularly physical activity and dietary intake, will likely contribute to a worsening prevalence of obesity, hypertension, hypercholesterolemia, and dysglycemia as the current US adolescent population reaches adulthood. Population-wide emphasis on establishment of ideal cardiovascular health behaviors early in life is essential for maintenance of ideal cardiovascular health throughout the lifespan.
Investing Overseas Without Moving Factories Abroad: The Case of Chinese Outward Direct Investment
Authors: Huang Yiping , Wang Bijun
Published: April 2013

Chinese outward direct investment (ODI) is unique in the sense that it starts in the early stage of economic development and does not move factories overseas. Empirical analyses using firm-level data confirm that the main purpose of Chinese ODI is to strengthen domestic production and productivity by acquiring strategic assets overseas. This Chinese style of ODI, which is different from Japanese efficiency-seeking ODI or American market-seeking ODI, is mainly underscored by significant cost advantage and abundant foreign exchange. We suggest that there might be a life cycle of ODI, which evolves from the Chinese style to the Japanese style and then to the American style as the economy develops. Following this proposition, we expect a major wave of ODI by Chinese small-sized and medium-sized manufacturing enterprises in the coming decade.
Urbanization and Inequality in Asia
Authors: Kanbur Ravi , Zhuang Juzhong
Published: April 2013

This paper provides a quantitative analysis of how the changing dual economic structure and urbanization affect inequality in Asia. Focusing on data for four countries—the Peoples’ Republic of China, India, Indonesia, and the Philippines—the paper asks three questions. First, how much of the past increase in inequality can be attributed to urbanization per se—the rising share of urban population, as opposed to other drivers related to the region's dual economic structure, such as the urban–rural income gap, inequality within the urban sector, and inequality within the rural sector? Second, how might urbanization affect these countries’ inequality in the future as its process continues? Third, moving forward, what is the relative importance of each of these drivers in containing rising inequality in Asia? It is hoped that the framework developed and calculations presented in this paper provide more insights into the dynamics of rising inequality in Asia and can help policy makers prioritize policy actions for confronting it.
Description of the newly-hatched juvenile of Aegla paulensis (Decapoda, Anomura, Aeglidae)
Authors: DE MORAES JULIANA CRISTINA BERTACINI , BUENO SÉRGIO LUIZ DE SIQUEIRA
Published: April 2013

The postembryonic development of Aegla paulensis is epimorphic (= direct), in which the hatching form is a juvenile that morphologically resembles the adult. Hatching is asynchronous, taking 3–5 days for all juveniles from a single brood to hatch. This paper provides a complete description of the external morphology of the newly-hatched juvenile of A. paulen-sis as analyzed through light microscopy (LM) and scanning electron microscopy (SEM). One of the striking features ob-served in the newly-hatched juvenile of A. paulensis was the presence of four pairs of rudimentary pleopods, a trait never described before in early juveniles of Aegla. Additional novelties include three unique types of setae and two types of pore sensilla.
Hypsilara breweri n.sp. from Venezuela: description of new species with notes on the morphology and phylogenetic relationships of the genus (Coleoptera: Elmidae: Larainae)
Authors: ČIAMPOR FEDOR JR , LAŠŠOVÁ KRISTÍNA , ČIAMPOROVÁ-ZAŤOVIČOVÁ ZUZANA
Published: April 2013

A new species of the genus Hypsilara Maier & Spangler, 2011, collected in the Eastern Venezuela, is described and illus-trated. We provide habitus photographs, detail drawings of both male and female genitalia, and description of some mor-phological features, which were omitted in the description of the genus. Included are also remarks on the distribution and genetic distance of the Hypsilara species and possible relations to other South American Larainae.
Macrostylopyga gen. nov., a new genus of cockroaches (Dictyoptera: Blattidae), with descriptions of two new species
Authors: ANISYUTKIN LEONID N. , ANICHKIN ALEXANDR E. , THINH NGUYEN VAN
Published: April 2013

The genus Macrostylopyga gen. nov. and two species (M. grandis sp. nov. and M. bidupi sp. nov.) are described. A de-tailed morphological description with special attention to the male genitalic structures is provided. Some aspects of the evolution of wingless cockroaches are briefly discussed.
Four new species of the genus Lobrathium Mulsant & Rey (Coleoptera: Staphylinidae: Paederinae) from China
Authors: WEBER XIAO-YAN LI , SOLODOVINIKOV ALEXEY , ZHOU HONG-ZHANG
Published: April 2013

Four new species of the genus Lobrathium Mulsant & Rey, 1878 from the mainland China are described: L. quadrum sp. n. from Sichuan, L. rutilum sp. n. from Hubei, L. tortuosum sp. n. from Zhejiang and L. zonalis sp. n. from Sichuan. In addition, the paper reviews the history of the research on the Chinese fauna of the genus. Some important morphological characters are illustrated for the new species.