bluuebunny/crossref_metadata_2025 huggingface dataset:
Dark-soliton collisions for a coupled AB system in the geophysical fluids or nonlinear optics
Authors: Xie Xi-Yang , Meng Gao-Qing
Published: January 2018

Under investigation in this paper is a coupled AB system, which describes the marginally unstable baroclinic wave packets in the geophysical fluids or ultra-short pulses in nonlinear optics. As the dark solitons are more resistant against various perturbations than the bright ones, we aim to investigate the dark solitons in the geophysical fluids or nonlinear optics. Dark one- and two-soliton solutions for such a system are derived based on the bilinear forms and propagations of the one solitons and collisions between the two solitons are graphically illustrated and analyzed. Further, influences of the coefficients [Formula: see text] and [Formula: see text] on the solitons are discussed, where [Formula: see text] is a parameter measuring the state of the basic flow and [Formula: see text] is the group velocity. The dark-one solitons with invariant shapes and amplitudes are viewed, and elastic collisions between the dark-two solitons are observed. Also, elastic collision between the bright and dark solitons is viewed, and the dark soliton is found to possess two peaks. [Formula: see text] is found to affect the widths of the dark-one solitons and the travelling directions of the dark-two solitons. It is shown that [Formula: see text] cannot influence shapes of [Formula: see text] and [Formula: see text], but affect the plane of the one soliton for [Formula: see text], and the two-peak dark soliton for [Formula: see text] changes to the single-peak one with the value of [Formula: see text] decreasing, where [Formula: see text] and [Formula: see text] are the packets of short waves and [Formula: see text] is the mean flow.
Reflection performance research of grating with polarization independence based on a sandwiched structure
Authors: Pei Hao , Wang Bo , Zhu Wenhua , Yin Sufang , Chen Li , Lei Liang , Zhou Jinyun
Published: January 2018

The novel reflective grating was studied under Littrow incidence as one sort of high-efficiency optical element. A covering layer and a dielectric layer are employed in this structure to achieve higher efficiency and wider bandwidth. For the given wavelength of 1550 nm, by using two-beam-interference theory of modal method, duty cycle and period of grating can be calculated, where the physical essence of high efficiency in the first-order is well explained by the modal method. The other grating parameters are optimized by using rigorous coupled-wave analysis. The optimized grating has an appropriate aspect ratio and shows that diffraction efficiencies of TE and TM polarizations in the first-order are greater than 97%. Compared with the reported surface-relief high-efficiency grating, the diffraction efficiencies of the proposed grating for TE and TM polarizations can be greatly improved.
KINETIC BEHAVIOR OF ELEMENTAL MERCURY SORPTION ON CERIUM- AND LANTHANUM-BASED COMPOSITE OXIDES
Authors: LIU DONGJING , ZHOU WEIGUO , WU JIANG
Published: January 2018

The kinetic behavior of gas phase mercury sorption on ZSM-5 supported cerium- and lanthanum-based composite oxides in the temperature range of 120–240∘C is investigated. The Hg0 sorption abilities all first increase and then decrease with the elevation of the temperatures, the cerium-based composite oxides show better Hg0 sorption abilities than that of the lanthanum-based composite oxides. CeO2–Mn2O3/ZSM-5 performs the best Hg0 sorption ability with Hg0 removal efficiency of nearly 100% at 180∘C. Doping Cu or Mn into La2O3 lattice causes the decrease in the Hg0 removal efficiency of the lanthanum-based composite oxides due to the formation of perovskite or perovskite-like compounds. The sorption of elemental mercury over metal oxides is governed both by diffusion processes as well as chemical reactions, and the sorption of elemental mercury on the cerium- and lanthanum-based composite oxides are chemisorption processes.
COMPUTING CREDIT VALUATION ADJUSTMENT FOR BERMUDAN OPTIONS WITH WRONG WAY RISK
Authors: FENG QIAN , OOSTERLEE CORNELIS W.
Published: January 2018

We study the impact of wrong way risk (WWR) on credit valuation adjustment (CVA) for Bermudan options. WWR is modeled by a dependency between the underlying asset and the intensity of the counterparty’s default. Two WWR models are proposed, based on a deterministic function and a CIR-jump (CIRJ) model, respectively. We present a nonnested Monte Carlo approach for computing CVA–VaR and CVA–expected shortfall (ES) for Bermudan options. By varying correlation coefficients, we study the impact of credit quality and WWR on the optimal exercise boundaries and CVA values of Bermudan products. Stress testing is performed.
Elders’ fall detection based on biomechanical features using depth camera
Authors: Xu Tao , Zhou Yun
Published: January 2018

An accidental fall poses a serious threat to the health of the elderly. With the advances of technology, an increased number of surveillance systems have been installed in the elderly home to help medical staffs find the elderly at risk. Based on the study of human biomechanical equilibrium, we proposed a fall detection method based on 3D skeleton data obtained from the Microsoft Kinect. This method leverages the accelerated velocity of Center of Mass (COM) of different body segments and the skeleton data as main biomechanical features, and adopts Long Short-Term Memory networks (LSTM) for fall detection. Compared with other fall detection methods, it does not require older people to wear any other sensors and can protect the privacy of the elderly. According to the experiment to validate our method using the existing database, we found that it could efficiently detect the fall behaviors. Our method provides a feasible solution for the fall detection that can be applied at homes of the elderly.
Attribute recognition from clothing using a Faster R-CNN based multitask network
Authors: Sun Yuhang , Liu Qingjie
Published: January 2018

Appearance information such as clothing and hairstyle can provide rich clues to identify a person in surveillance videos. This paper proposes a Faster R-CNN based multi-task neural network to recognize attributes such as gender, nationality, etc. from clothing of a person. Toward this end, a fine-tuned Faster R-CNN is applied to locate people in images. Then hierarchical features are extracted from these regions to perform attributes recognition. The recognition network and Faster R-CNN share the same weights, and they can be trained in an end-to-end manner. Experiments are conducted on a newly collected and well-labeled image dataset. The experimental results show that our network can locate a human body and identify its attributes efficiently.
Cross-device hand vein recognition based on improved SIFT
Authors: Wang Yiding , Zheng Xuan
Published: January 2018

The recognition rate of SIFT algorithm in single hand vein database has been as high as 99.5%. But with the development of Internet-plus technology, the demand for distributed systems becomes more and more significant. However, the problem of picture quality caused by cross-device makes the intraclass variations larger. For example, when gathering the dorsal hand vein images, subtle changes in relative distance and orientation among the imaging camera, the illumination LED arrays and the different location of users’ hand, as well as shielding by the external housing box from ambient light sources and so on, these will make large difference to one person’s hand images. So, including the contrast, the lightness, the shifting, the angle of rotation, the size and so on, these differences make it possible to use some traditional methods to recognize dorsal hand vein with a low recognition rate of less than 50%. Therefore, based on the traditional SIFT, this paper optimized the scale factor [Formula: see text], extreme searching neighborhood structure and matching threshold [Formula: see text]. It can be seen that the cross-device hand vein feature is more robust, and the recognition rate reached an average of 88.5%.
Robust video-based face recognition via M-estimator and image set collaborative representation
Authors: Deng Lei , Shi Jing , Wang Yulong
Published: January 2018

This paper presents a novel method for video-based face recognition (VFR) based on M-estimator and image set collaborative representation. Since a video is essentially an image set, the VFR problem can be cast as a special case of the image set-based face recognition (FR) problem. To measure the distance between the query image set and the gallery image set, we develop an M-estimator-based image set collaborative representation (MISCR) model. To implement MISCR, we devise an efficient half-quadratic-based optimization algorithm to tackle the complicated optimization problem. We also establish the convergence property of the devised algorithm. Our other contribution is to propose an MISCR-based classifier for the general image set classification problem, including VFR as a special case. The experiments using real-world benchmark databases demonstrate the efficacy and robustness of the proposed method for VFR.
Effective human detection via multi-model classification and adaptive late fusion
Authors: Zhu Chao , Yin Xu-Cheng
Published: January 2018

Human detection serves as an important basis to achieve certain video surveillance-oriented biometrics such as gait, face and actions since the first step is to find and locate human targets in surveillance scenes. In the literature, channel feature-based methods and deep neural network-based methods are two most popular kinds of human detection approaches, with their own advantages. However, there is not much effort on the study of their combination to take full advantage of these two kinds of approaches. Therefore in this paper, we propose an effective human detection approach by combining multiple state-of-the-art deep neural network-based and channel feature-based methods with an adaptive late fusion strategy. The key idea of our approach is to explore complementary information of different state-of-the-art detection methods and to find an appropriate way to combine their strong points for better performance. The proposed approach is evaluated on several standard human detection benchmarks, and shows its effectiveness by achieving superior performances to the other state-of-the-art methods on most evaluation settings.
A cryptosystem for lossless/lossy grayscale images in IWT domain using chaotic map-based generated key matrices
Authors: Naik Kshiramani , Pal Arup Kumar
Published: January 2018

In this paper, an image encryption scheme based on reversible integer wavelet transform (IWT) with chaotic logistic map is designed. The proposed cryptosystem is applicable to encipher both the medical and natural images in lossless and lossy manners, respectively. Initially, the original image is transformed with the multilevel of IWT, then the image data set is divided into low sub-band (approximation part) and high sub-bands (detail part). The approximation part gets confused with the chaotic logistic map followed by the bit plane decomposition. Next, the individual bit planes are further diffused with several binary key metrics, generated using a chaotic logistic map. The proposed key schedule derives several large size of binary key metrics from a small size of key. Based on the type of applications, the detail part is considered for lossless/lossy compression. The lossless/lossy compressed detail part is further considered only for confusion process using the logistic map for the sake of enhancing the security level. Finally, the cipher image obtained after inverse IWT is significantly dissimilar than original image. The scheme has been tested on several standard medical and natural images and the experimental results substantiate that a small size of key is enough to protect the content of images completely. The security analysis reveals that the proposed scheme is suitable for protecting the image data effectively.
An Efficient Topology Optimization Method for Structures with Uniform Stress
Authors: Chu Sheng , Gao Liang , Xiao Mi
Published: January 2018

This paper focuses on two kinds of bi-objective topology optimization problems with uniform-stress constraints: compliance-volume minimization and local frequency response–volume minimization problems. An adaptive volume constraint (AVC) algorithm based on an improved bisection method is proposed. Using this algorithm, the bi-objective uniform-stress-constrained topology optimization problem is transformed into a single-objective topology optimization problem and a volume-decision problem. The parametric level set method based on the compactly supported radial basis functions is employed to solve the single-objective problem, in which a self-organized acceleration scheme based on shape derivative and topological sensitivity is proposed to adaptively adjust the derivative of the objective function and the step length during the optimization. To solve the volume-decision problem, an improved bisection method is proposed. Numerical examples are tested to illustrate the feasibility and effectiveness of the self-organized acceleration scheme and the AVC algorithm based on the improved bisection method. An extended application to the bi-objective stress-constrained topology optimization of a structure with stress concentration is also presented.
A Posteriori Error Analysis for the Weak Galerkin Method for Solving Elliptic Problems
Authors: Zhang Tie , Chen Yanli
Published: January 2018

In this paper, we study the a posteriori error estimate for weak Galerkin finite element method solving elliptic problems. A residual type error estimator is proposed and is proven to be reliable and efficient. This estimator provides global upper and lower bounds on the exact error in a discrete [Formula: see text]-norm. Numerical experiments are given to illustrate the effectiveness of the proposed error estimator.
Improved wavelet hierarchical threshold filter method for optical coherence tomography image de-noising
Authors: Cao Jing , Wang Pinghe , Wu Bo , Shi Guohua , Zhang Yan , Li Xiqi , Zhang Yudong , Liu Yong
Published: January 2018

According to the speckle feature in Optical coherence tomography (OCT), images with speckle indicate not only noise but also signals, an improved wavelet hierarchical threshold filter (IWHTF) method is proposed. At first, a modified hierarchical threshold-selected algorithm is used to prevent signals from being removed by assessing suitable thresholds for different noise levels. Then, an improved wavelet threshold function based on two traditional threshold functions is proposed to trade-off between speckle removing and sharpness degradation. The de-noising results of an OCT finger skin image shows that the IWHTF method obtains better objective evaluation metrics and visual image quality improvement. When [Formula: see text], [Formula: see text] and [Formula: see text], the improved method can achieve 9.58[Formula: see text]dB improvement in signal-to-noise ratio, with sharpness degraded by 3.81%.
Self-Governance and the Effects of Rules in Irrigation Systems: Evidence from Laboratory and Framed Field Experiments in China, India and Vietnam
Authors: Pham Lan T. , Otto Ilona M. , Zikos Dimitrios
Published: January 2018

This paper employs laboratory and framed field experiments to investigate factors influencing the behavior of irrigation users, with an emphasis on the effects of exogenously and endogenously designed allocation rules. The experiments were conducted with 36 groups of farmers and students from China, India and Vietnam. The results show that physically asymmetric access to water as a resource creates an asymmetric distribution of investments, harvests and revenues that favors upstream users. Exogenously designed allocation rules appear able to equalize the distribution of revenue between upstream and downstream users, but are also likely to reduce the volume of investment and generated revenue. Meanwhile, communication between irrigation users with the possibility of endogenously designed rules appears to have a stronger equalizing effect on asymmetric resource access but also increases overall investment, which then increases water availability in a hypothetical irrigation channel. This suggests that promoting participation of irrigation users in designing rules for water distribution, water use monitoring and sanctioning might improve the performance of irrigation systems.
A distributed timing synchronization technique for parallel multi-core instruction-set simulation
Authors: Wu Meng-Huan , Fu Cheng-Yang , Wang Peng-Chih , Tsay Ren-Song
Published: January 2018

As multi-core architecture has become the mainstream, the corresponding multi-core instruction-set simulation (MCISS) is also needed to aid system development. Ideally, we may run a MCISS in parallel to enhance the simulation speed. However, the conventional centralized timing synchronization mechanism would greatly constrain the parallelism of a MCISS, so the simulation speed is bounded. To resolve this issue, we propose a new distributed timing synchronization technique which allows higher parallelism for a MCISS. Hence, it accelerates the simulation speed by 9 to 20 times as the number of cores increases in contrast to the centralized synchronization approach.
MultiMaKe
Authors: Bathen Luis Angel D. , Ahn Yongjin , Pasricha Sudeep , Dutt Nikil D.
Published: January 2018

The increasing demand for low-power and high-performance multimedia embedded systems has motivated the need for effective solutions to satisfy application bandwidth and latency requirements under a tight power budget. As technology scales, it is imperative that applications are optimized to take full advantage of the underlying resources and meet both power and performance requirements. We propose MultiMaKe, an application mapping design flow capable of discovering and enabling parallelism opportunities via code transformations, efficiently distributing the computational load across resources, and minimizing unnecessary data transfers. Our approach decomposes the application's tasks into smaller units of computations called kernels, which are distributed and pipelined across the different processing resources. We exploit the ideas of inter-kernel data reuse to minimize unnecessary data transfers between kernels, early execution edges to drive performance, and kernel pipelining to increase system throughput. Our experimental results on JPEG and JPEG2000 show up to 97% off-chip memory access reduction, and up to 80% execution time reduction over standard mapping and task-level pipelining approaches.
Timing effects of DDR memory systems in hard real-time multicore architectures
Authors: Paolieri Marco , Quiñones Eduardo , Cazorla Francisco J.
Published: January 2018

Multicore processors are an effective solution to cope with the performance requirements of real-time embedded systems due to their good performance-per-watt ratio and high performance capabilities. Unfortunately, their use in integrated architectures such as IMA or AUTOSAR is limited by the fact that multicores do not guarantee a
time composable
behavior for the applications: the WCET of a task depends on inter-task interferences introduced by other tasks running simultaneously.

This article focuses on the off-chip memory system: the hardware shared resource with the highest impact on the WCET and hence the main impediment for the use of multicores in integrated architectures. We present an analytical model that computes the worst-case delay, also known as
Upper Bound Delay
(UBD), that a memory request can suffer due to memory interferences generated by other co-running tasks. By considering the UBD in the WCET analysis, the resulting WCET estimation is independent from the other tasks, hence ensuring the time composability property and enabling the use of multicores in integrated architectures. We propose a memory controller for hard real-time multicores compliant with the analytical model that implements extra hardware features to deal with refresh operations and interferences generated by co-running non hard real-time tasks.
Fiat-shamir identification scheme immune to the hardware fault attacks
Authors: Kim Sung-Kyoung , Kim Tae Hyun , Hong Seokhie
Published: January 2018

The Fiat-Shamir identification scheme is popular for “light” consumer devices, such as smart cards, in a wide range of consumer services. However, it can be vulnerable to fault attacks, even though a cryptographic algorithm is theoretically secure. Thus, a study on cryptanalysis and countermeasures to fault attacks is crucial. This article proposes a secure and practical modification of the Fiat-Shamir identification scheme resistant against fault attacks. A straightforward protection is to check integrity of the intermediate values and outputs at each step. However, this approach may be a bottleneck of the entire scheme and are attained at the expense of increased computational overhead that is similar to the overhead of the identification scheme. The proposed scheme is designed to propagate faults induced in a target variable to other parts without conditional branches. Therefore, a relatively small overhead enables implementation of the proposed scheme in small cryptographic devices such as smart cards.
SparseX
Authors: Elafrou Athena , Karakasis Vasileios , Gkountouvas Theodoros , Kourtis Kornilios , Goumas Georgios , Koziris Nectarios
Published: January 2018

The Sparse Matrix-Vector Multiplication (SpMV) kernel ranks among the most important and thoroughly studied linear algebra operations, as it lies at the heart of many iterative methods for the solution of sparse linear systems, and often constitutes a severe performance bottleneck. Its optimization, which is intimately associated with the data structures used to store the sparse matrix, has always been of particular interest to the applied mathematics and computer science communities and has attracted further attention since the advent of multicore architectures. In this article, we present SparseX, an open source software package for SpMV targeting multicore platforms, that employs the state-of-the-art
Compressed Sparse eXtended
(CSX) sparse matrix storage format to deliver high efficiency through a highly usable “BLAS-like” interface that requires limited or no tuning. Performance results indicate that our library achieves superior performance over competitive libraries on large-scale problems.
Simultaneous Conversions with the Residue Number System Using Linear Algebra
Authors: Doliskani Javad , Giorgi Pascal , Lebreton Romain , Schost Eric
Published: January 2018

We present an algorithm for simultaneous conversions between a given set of integers and their Residue Number System representations based on linear algebra. We provide a highly optimized implementation of the algorithm that exploits the computational features of modern processors. The main application of our algorithm is matrix multiplication over integers. Our speed-up of the conversions to and from the Residue Number System significantly improves the overall running time of matrix multiplication.
Survey on Access Control for Community-Centered Collaborative Systems
Authors: Paci Federica , Squicciarini Anna , Zannone Nicola
Published: January 2018

The last decades have seen a growing interest and demand for community-centered collaborative systems and platforms. These systems and platforms aim to provide an environment in which users can collaboratively create, share, and manage resources. While offering attractive opportunities for online collaboration and information sharing, they also open several security and privacy issues. This has attracted several research efforts toward the design and implementation of novel access control solutions that can handle the complexity introduced by collaboration. Despite these efforts, transition to practice has been hindered by the lack of maturity of the proposed solutions. The access control mechanisms typically adopted by commercial collaborative systems like online social network websites and collaborative editing platforms, are still rather rudimentary and do not provide users with a sufficient control over their resources. This survey examines the growing literature on access control for collaborative systems centered on communities, and identifies the main challenges to be addressed in order to facilitate the adoption of collaborative access control solutions in real-life settings. Based on the literature study, we delineate a roadmap for future research in the area of access control for community-centered collaborative systems.
A Comprehensive Taxonomy of Fragmentation and Allocation Techniques in Distributed Database Design
Authors: Nashat Dalia , Amer Ali A.
Published: January 2018

The need to design an optimally distributed database is increasingly important with the growth of information technology and computer networks. However, designing a distributed database is an extremely complex process due to a large number of geographically distributed sites and database relations. Moreover, decreasing communication costs and query response time should be taken into consideration. There are three main techniques applied to design a distributed database, namely Fragmentation, Data allocation, and Replication. It is notable that these techniques are often treated separately and rarely processed together. Some available allocation methods are applied regardless of how the fragmentation technique is performed or replication process is adopted. In contrast, other fragmentation techniques do not consider the allocation or the replication techniques. Therefore, the first and foremost step for designing an optimal database is to develop a comprehensive understanding of the current fragmentation, replication, and allocation techniques and their disadvantages. This article presents an attempt to fulfill this step by proposing a comprehensive taxonomy of the available fragmentation and allocation techniques in distributed database design. The article also discusses some case studies of these techniques for a deeper understanding of its achievements and limitations.
HPC Cloud for Scientific and Business Applications
Authors: Netto Marco A. S. , Calheiros Rodrigo N. , Rodrigues Eduardo R. , Cunha Renato L. F. , Buyya Rajkumar
Published: January 2018

High performance computing (HPC) clouds are becoming an alternative to on-premise clusters for executing scientific applications and business analytics services. Most research efforts in HPC cloud aim to understand the cost benefit of moving resource-intensive applications from on-premise environments to public cloud platforms. Industry trends show that hybrid environments are the natural path to get the best of the on-premise and cloud resources—steady (and sensitive) workloads can run on on-premise resources and peak demand can leverage remote resources in a pay-as-you-go manner. Nevertheless, there are plenty of questions to be answered in HPC cloud, which range from how to extract the best performance of an unknown underlying platform to what services are essential to make its usage easier. Moreover, the discussion on the right pricing and contractual models to fit small and large users is relevant for the sustainability of HPC clouds. This article brings a survey and taxonomy of efforts in HPC cloud and a vision on what we believe is ahead of us, including a set of research challenges that, once tackled, can help advance businesses and scientific discoveries. This becomes particularly relevant due to the fast increasing wave of new HPC applications coming from big data and artificial intelligence.
Global and Local Deadlock Freedom in BIP
Authors: Attie Paul C. , Bensalem Saddek , Bozga Marius , Jaber Mohamad , Sifakis Joseph , Zaraket Fadi A.
Published: January 2018

We present a criterion for checking local and global deadlock freedom of finite state systems expressed in BIP: a component-based framework for constructing complex distributed systems. Our criterion is evaluated by model-checking a set of subsystems of the overall large system. If satisfied in small subsystems, it implies deadlock-freedom of the overall system. If not satisfied, then we re-evaluate over larger subsystems, which improves the accuracy of the check. When the subsystem being checked becomes the entire system, our criterion becomes complete for deadlock-freedom. Hence our criterion only fails to decide deadlock freedom because of computational limitations: state-space explosion sets in when the subsystems become too large. Our method thus combines the possibility of fast response together with theoretical completeness. Other criteria for deadlock freedom, in contrast, are incomplete in principle, and so may fail to decide deadlock freedom even if unlimited computational resources are available. Also, our criterion certifies freedom from local deadlock, in which a subsystem is deadlocked while the rest of the system executes. Other criteria only certify freedom from global deadlock. We present experimental results for dining philosophers and for a multi-token-based resource allocation system, which subsumes several data arbiters and schedulers, including Milner’s token-based scheduler.
Underwater Wireless Sensor Networks
Authors: Coutinho Rodolfo W. L. , Boukerche Azzedine , Vieira Luiz F. M. , Loureiro Antonio A. F.
Published: January 2018

Underwater wireless sensor networks (UWSNs) will pave the way for a new era of underwater monitoring and actuation applications. The envisioned landscape of UWSN applications will help us learn more about our oceans, as well as about what lies beneath them. They are expected to change the current reality where no more than 5% of the volume of the oceans has been observed by humans. However, to enable large deployments of UWSNs, networking solutions toward efficient and reliable underwater data collection need to be investigated and proposed. In this context, the use of topology control algorithms for a suitable, autonomous, and on-the-fly organization of the UWSN topology might mitigate the undesired effects of underwater wireless communications and consequently improve the performance of networking services and protocols designed for UWSNs. This article presents and discusses the intrinsic properties, potentials, and current research challenges of topology control in underwater sensor networks. We propose to classify topology control algorithms based on the principal methodology used to change the network topology. They can be categorized in three major groups: power control, wireless interface mode management, and mobility assisted–based techniques. Using the proposed classification, we survey the current state of the art and present an in-depth discussion of topology control solutions designed for UWSNs.
Scaling Algorithms for Weighted Matching in General Graphs
Authors: Duan Ran , Pettie Seth , Su Hsin-Hao
Published: January 2018

We present a new scaling algorithm for maximum (or minimum) weight perfect matching on general, edge weighted graphs. Our algorithm runs in
O
(
m
√
n
log(
nN
)) time,
O
(
m
√
n
) per scale, which matches the running time of the best cardinality matching algorithms on sparse graphs [16, 20, 36, 37]. Here,
m
,
n
, and
N
bound the number of edges, vertices, and magnitude, respectively, of any integer edge weight. Our result improves on a 25-year-old algorithm of Gabow and Tarjan, which runs in
O
(
m
√
n
log
n
α (
m
,
n
) log(
nN
)) time.
Reducing Curse of Dimensionality
Authors: Chan T.-H. Hubert , Jiang Shaofeng H.-C.
Published: January 2018

We consider the Traveling Salesman Problem with Neighborhoods (TSPN) in doubling metrics. The goal is to find the shortest tour that visits each of a given collection of subsets (regions or neighborhoods) in the underlying metric space.

We give a randomized polynomial-time approximation scheme (PTAS) when the regions are fat weakly disjoint. This notion of regions was first defined when a QPTAS was given for the problem in SODA 2010 (Chan and Elbassioni 2010). The regions are partitioned into a constant number of groups, where in each group, regions should have a common upper bound on their diameters and each region designates one point within it such that these points are far away from one another.

We combine the techniques in the previous work, together with the recent PTAS for TSP (STOC 2012: Bartal, Gottlieb, and Krauthgamer 2012) to achieve a PTAS for TSPN. However, several nontrivial technical hurdles need to be overcome for applying the PTAS framework to TSPN:

(1) Heuristic to detect sparse instances. In the STOC 2012 paper, a minimum spanning tree heuristic is used to estimate the portion of an optimal tour within some ball. However, for TSPN, it is not known if an optimal tour would use points inside the ball to visit regions that intersect the ball.

(2) Partially cut regions in the recursion. After a sparse ball is identified by the heuristic, the PTAS framework for TSP uses dynamic programming to solve the instance restricted to the sparse ball and recurse on the remaining instance. However, for TSPN, it is an important issue to decide whether each region partially intersecting the sparse ball should be solved in the sparse instance or considered in the remaining instance.

Surprisingly, we show that both issues can be resolved by conservatively making the ball in question responsible for all intersecting regions. In particular, a sophisticated charging argument is needed to bound the cost of combining tours in the recursion.

Moreover, more refined procedures are used to improve the dependence of the running time on the doubling dimension
k
from the previous exp[(
O
(1))

k
2

] (even for just TSP) to exp[2

O
(
k
log
k
)

].
A demonstration of computing galois groups of polynomials in magma
Authors: Sutherland Nicole
Published: January 2018

We demonstrate some of the computations of Galois groups which are possible in Magma [1].
Computing tropical varieties using Newton's polygon method
Authors: Ren Yue
Published: January 2018

We will demonstrate software for fast computation of tropical varieties. We give a brief overview of the first techniques developed by Bogart-Jensen-Speyer-Sturmfels-Thomas and show how its bottlenecks can be avoided, relying theoretically on recent results on the intersection of tropical varieties and practically on well-known algorithms in computer algebra.
Abstracts of recent doctoral dissertations in computer algebra
Authors: Tuncer Yusuf Baris
Published: January 2018

Each quarter we are pleased to present abstracts of recent doctoral dissertations in Computer Algebra and Symbolic Computation. We encourage all recent Ph.D. graduates who have defended in the past two years (and their supervisors), to submit their abstracts for publication in CCA.

Please send abstracts to the CCA editors

for consideration.
Using DDS middleware in distributed partitioned systems
Authors: García-Valls Marisol , Domínguez-Poblete Jorge , Touahria Imad Eddine
Published: January 2018

Communication middleware technologies are slowly being integrated also into critical domains that are also progresively transitioning to partitioned systems. Especially, avionics systems have transitioned from federated architectures to IMA (Integrated Modular Avionics) standard that targets partitioned systems to comply with the requirements of cost, safety, and weight. In the future developments, it is fully considered the integration of middleware to support data communication and application interoperability. As specified in FACE (Future Airborne Capability Environment), middleware will be integrated into mixed criticality systems to ease the development of portable components that can interoperate effectively. Still nowadays, in realtime environments, communication middleware is perceived as a source of unpredictability; and still there are very few contributions that present real applications of the integration of communication middleware into partitioned systems to support distribution.

This paper describes the usage of a publish-subscribe middleware (precisely, DDS -Data Distribution Service for real-time systems-) into a fully distributed partitioned system. We explain the design of a reliable communication setting enabled by the middleware, and we exemplify it using a distributed monitoring application for an emulated partitioned system with the goal of obtaining the middleware communication overhead. Implementation results show stable communication times that can be integrated in the resource assignment to partitions.
Cost minimization of network services with buffer and end-to-end deadline constraints
Authors: Millnert Victor , Bini Enrico , Eker Johan
Published: January 2018

Cloud computing technology provides the means to share physical resources among multiple users and data center tenants by exposing them as virtual resources. There is a strong industrial drive to use similar technology and concepts to provide timing sensitive services. One such is virtual networking services, so called services chains, which consist of several interconnected virtual network functions. This allows for the capacity to be scaled up and down by adding or removing virtual resources. In this work, we develop a model of a service chain and pose the dynamic allocation of resources as an optimization problem. We design and present a set of strategies to allot virtual network nodes in an optimal fashion subject to latency and buffer constraints.
Acid retention in chronic kidney disease is inversely related to GFR
Authors: Goraya Nimrit , Simoni Jan , Sager Lauren N. , Pruszynski Jessica , Wesson Donald E.
Published: January 2018

Greater H+retention in animal models of chronic kidney disease (CKD) mediates faster glomerular filtration rate (GFR) decline and dietary H+reduction slows eGFR decline in CKD patients with reduced eGFR and H+retention due to the high acid (H+) diets of developed societies. We examined if H+retention in CKD is inversely associated with estimated GFR (eGFR) using cross-sectional and longitudinal analysis of individuals with CKD stage 1 (>90 ml·min− 1·1.73 m−2), CKD stage 2 (60–89 ml/min per 1.73 m2), and CKD stage 3 (30–59 ml·min− 1·1.73 m−2) eGFR. H+retention was assessed using the difference between observed and expected plasma total CO22 h after 0.5 meq/kg body wt oral NaHCO3. H+retention was higher in CKD 2 vs. CKD 1 ( P < 0.01) and in CKD 3 vs. CKD 2 ( P < 0.02) at baseline and 5 yr, and was higher in CKD 2 vs. CKD 1 ( P < 0.01) at 10 yr. All groups had lower eGFR at subsequent time points ( P < 0.01) but H+retention was not different among the three time points for CKD 1. By contrast, eGFR decrease was associated with higher H+retention in CKD 2 at 5 yr ( P = 0.04) and 10 yr ( P < 0.01) and with higher H+retention in CKD 3 at 5 yr ( P < 0.01). Yearly eGFR decline rate was faster in CKD 2 vs. CKD 1 ( P < 0.01) and in CKD 3 vs. CKD 2 ( P < 0.01). The data show that H+retention is inversely associated with eGFR, with faster eGFR decline, and support the need for greater dietary H+reduction therapy for CKD individuals with lower eGFR.
The Anti‐Inflammatory Effect of Fructus Kochiae on Allergic Contact Dermatitis Rats via pERK1/2/TLR4/NF‐κB Pathway Activation
Authors: Xiao Zuoqi , Xiao Suxi , Zhang Yongning , Pan Tao , Ouyang Bo
Published: January 2018

Allergic contact dermatitis (ACD) is a common irritability skin disease, which can be cured by using the Chinese patent medicine. To explore the pharmacological effect of total flavonoids of Fructus Kochiae (FK) on ACD, we used dinitrochlorobenzene‐ (DNCB‐) induced ACD rats. Five groups were used in our experiments. The normal group and the DNCB group were treated with 0.5% CMC‐Na; the DNCB + hFK group was treated with a high dose of total flavonoids of FK (200 mg/kg); the DNCB + lFK group was treated with a low dose of FK (100 mg/kg); the DNCB + Pre group was treated with prednisolone acetate (2.5 mg/kg). The results showed that FK treatment had significantly attenuated the inflammation induced by DNCB. The increased concentration of cytokines including IL‐6, IL‐18, and IFN‐γ in ACD rats could be reversed by the FK administration, while IL‐10 expressed the opposite result; the expression level of TLR4, pERK1/2, and NF‐κB could be downregulated by the treatment with FK in the ACD rat. In a word, the total flavonoids of the FK had an anti‐inflammatory effect on the DNCB‐induced ACD rat; this regulatory mechanism was highly possible based on the pERK1/2/TLR4‐NF‐κB pathway activation.
An Annotated List of Auchenorrhyncha and Heteroptera Collected in the Coastal Salt Marshes of the Mississippi Delta in Louisiana
Authors: Sokolov I. M. , Chen X. , Strecker R. M. , Hooper-Bùi L. M.
Published: January 2018

Insects that live in the saltwater and brackish marshes, which fringe the northern coast of the Gulf of Mexico, are largely unstudied. During 2011–2013, a survey of insect fauna of the coastal salt marshes of the Mississippi Delta in Louisiana was conducted. We present the species of terrestrial representatives of Heteroptera and Auchenorrhyncha collected during that study. The Auchenorrhyncha are represented by 33 species in 6 families, with Cicadellidae (16 species) and Delphacidae (13 spp.), and are the most diverse. The terrestrial heteropterans are represented by 11 species in 5 families with the majority of species in Miridae (6 spp.). A list of species, annotated with numbers of specimens collected, ranges of collection dates (seasonality), and published information on their hosts, habitats, and ranges, is presented. Of 44 identified species, ten species (22.7%) are reported from Louisiana for the first time. The paper provides evidence of a diverse terrestrial arthropod community in brackish marshes; a community that is largely understudied.
Factors Associated with Outcomes of Percutaneous Transluminal Renal Angioplasty in Patients with Renal Artery Stenosis: A Retrospective Analysis of 50 Consecutive Cases
Authors: Matayoshi Tetsutaro , Kamide Kei , Tanaka Ryoichi , Fukuda Tetsuya , Horio Takeshi , Iwashima Yoshio , Yoshihara Fumiki , Nakamura Satoko , Nakahama Hajime , Ohya Yusuke , Kawano Yuhei
Published: January 2018

Background. The results of recent trials have brought some confusion to the treatment strategy for renal artery stenosis (RAS). To evaluate the applicability of percutaneous transluminal renal angioplasty (PTRA) for RAS, we extracted the factors that may affect the effectiveness of PTRA from cases experienced at a hypertension center. Methods and Results. We retrospectively assessed the blood pressure (BP) lowering effects and renoprotective effects in 50 consecutive patients that had hemodynamically significant RAS and had undergone PTRA and stenting during 2001–2005. Subjects were diagnosed with atherosclerotic RAS (42), fibromuscular dysplasia (6), or Takayasu disease (2). After PTRA, BP significantly lowered from 152.3/80.3 mmHg to 132.6/73.2 mmHg (p<0.05), but the estimated glomerular filtration rate (eGFR) did not change significantly. There were no factors associated with the BP lowering effects of PTRA. The baseline resistive index (RI) was negatively correlated with the change in eGFR (p<0.05). After correction for age, sex, BMI, and the dose of contrast medium, the association of RI with change in eGFR remained significant. Conclusion. In cases with hemodynamically significant RAS, PTRA lowered BP but was not effective in improving renal function. Higher baseline RI may be a factor for predicting poor clinical course of renal function after PTRA.
Review on Carbon Dioxide Absorption by Choline Chloride/Urea Deep Eutectic Solvents
Authors: Isaifan Rima J. , Amhamed Abdukarem
Published: January 2018

In the recent past few years, deep eutectic solvents (DESs) were developed sharing similar characteristics to ionic liquids but with more advantageous features related to preparation cost, environmental impact, and efficiency for gas separation processes. Amongst many combinations of DES solvents that have been prepared, reline (choline chloride as the hydrogen bond acceptor mixed with urea as the hydrogen bond donor) was the first DES synthesized and is still the one with the lowest melting point. Choline chloride/urea DES has proven to be a promising solvent as an efficient medium for carbon dioxide capture when compared with amine alone or ionic liquids under the same conditions. This review sheds light on the preparation method, physical and chemical characteristics, and the CO2 absorption capacity of choline chloride/urea DES under different temperatures and pressures reported up to date.
Reduction of Aflatoxin M1 Levels during Ethiopian Traditional Fermented Milk (Ergo) Production
Authors: Shigute Tsige , Washe Alemayehu P.
Published: January 2018

In this study, the reduction of aflatoxin M1 (AFM1) levels during lab-scale ergo production was investigated through determination of the residual levels of AFM1 using Enzyme Linked Immunosorbent Assay. The results showed gradual and incubation time dependent reduction of AFM1 level in the raw milk samples being fermented to ergo. The maximum reductions of 57.33 and 54.04% were recorded in AFM1 in natural and LAB inoculums initiated fermentations, respectively, in 5 days of incubation. Although a significant difference (P=0.05) in the AFM1 decrease in the two types of fermentations was recorded, such findings could vary with milk samples depending on initial load of the microorganisms as determined by hygienic conditions. However, the level of AFM1 in control (sterilized) samples showed only a 5.5% decrease during the entire period of incubation. Microbiological investigation showed increasing LAB counts with incubation time. A gradual decrease in pH of the milk samples was observed during fermentation. Considering the fact that both viable and dead bacterial cells could remove AFM1 during ergo production, the mechanism is proposed as predominantly involving noncovalent binding of the toxin with the chemical components of the bacterial cell wall.
Prevalence of Low Birth Weight before and after Policy Change to IPTp-SP in Two Selected Hospitals in Southern Nigeria: Eleven-Year Retrospective Analyses
Authors: Igboeli Nneka U. , Adibe Maxwell O. , Ukwe Chinwe V. , Aguwa Nze C.
Published: January 2018

Background. In 2005, Nigeria changed its policy on prevention of malaria in pregnancy to intermittent preventive treatment with sulphadoxine-pyrimethamine (IPTp-SP). Indicators of impact of effective prevention and control of malaria on pregnancy (MIP) are low birth weight (LBW) and maternal anaemia by parity. This study determined the prevalence of LBW for different gravidity groups during periods of pre- and postpolicy change to IPTp-SP. Methods. Eleven-year data were abstracted from the delivery registers of two hospitals. Study outcomes calculated for both pre- (2000–2004) and post-IPTp-SP-policy (2005–2010) years were prevalence of LBW for different gravidity groups and risk of LBW in primigravidae compared to multigravidae. Results. Out of the 11,496 singleton deliveries recorded within the 11-year period, the prevalence of LBW was significantly higher in primigravidae than in multigravidae for both prepolicy (6.3% versus 4%) and postpolicy (8.6% versus 5.1%) years. The risk of LBW in primigravidae compared to multigravidae increased from 1.62 (1.17–2.23) in the prepolicy years to 1.74 (1.436–2.13) during the postpolicy years. Conclusion. The study demonstrated that both the prevalence and risk of LBW remained significantly higher in primigravidae even after the change in policy to IPTp-SP.