bluuebunny/crossref_metadata_2025 huggingface dataset:
Posterior superior internal impingement: an evidence-based review
Authors: Castagna Alessandro , Garofalo Raffaele , Cesari Eugenio , Markopoulos Nikolaos , Borroni Mario , Conti Marco
Published: April 2010

Over the last decade, the concept of internal impingement has continued to evolve, and the frequency with which this condition is recognised continues to increase. This syndrome should be clearly differentiated from the classical (external) impingement that is thought to be caused by compression of the subacromial bursa, long head of the biceps tendon and rotator cuff (RC) by the coraco-acromial arch. Internal (posterosuperior) impingement syndrome is typified by a painful shoulder due to impingement of the soft tissue, including the RC, joint capsule and the posterosuperior part of the glenoid. The aetiology of this syndrome is unclear, but hypotheses include anterior shoulder instability or micro-instability, contracture of the posterior capsule, reduced humeral retroversion and scapular dyskinesis. Non-operative therapy represents the first line of treatment for this syndrome and includes the management of pain, stretching of the posterior capsule and a muscle strengthening programme. Surgical treatment should only be considered when conservative management fails. A number of different surgical procedures have been proposed, but the results are variable. The success rate is generally improved when the subtle instability, associated with internal impingement, is also addressed.
Biomechanics and treatment of acromioclavicular and sternoclavicular joint injuries
Authors: Bontempo Nicholas A , Mazzocca Augustus D
Published: April 2010

Acromioclavicular (AC) joint injuries are more common than sternoclavicular (SC) joint injuries. There is a spectrum of AC joint traumatic injuries that ranges from a ligament sprain to a complete dislocation. The majority of AC joint injuries are successfully treated non-operatively with a period of sling immobilisation followed by progressive physical therapy and shoulder range of motion exercises. In patients who have symptomatic AC joint injuries that are recalcitrant to non-operative treatment there exists a variety of surgical treatment options to reconstruct and stabilise the joint. The SC joint, like the AC joint, can suffer a spectrum of ligamentous injuries; however, when it comes to dislocation it can only dislocate anteriorly or posteriorly. Anterior dislocations are often successfully treated with closed reduction. Posterior dislocations have significant clinical implications because of the proximity of surrounding vessels and nerves. Any attempt at reduction of a posterior dislocation requires the presence of a cardiothoracic surgeon. The majority of AC and SC joint injuries typically result in ligamentous sprain and heal uneventfully with a period of immobilisation. If, however, patients remain symptomatic after non-operative treatment or have a dislocated joint, there are reduction manoeuvres and surgical techniques that allow joint stabilisation.
Disorder of the long head of the biceps tendon
Authors: Ejnisman Benno , Monteiro Gustavo Cará , Andreoli Carlos Vicente , de Castro Pochini Alberto
Published: April 2010

This paper focuses on biceps injuries in shoulder surgery. This topic is currently of great interest, and there has been much discussion about diagnosis, treatment and prevention. Biceps tendon pathology exists in many forms and is frequently associated with other shoulder disorders. These facts must be taken into consideration in the evaluation and treatment of patients with long head of the biceps pathology. There is much controversy about the long head of the biceps tendon (LHBT). The clinical significance to shoulder function, diagnosis and treatment are still a source of debate. The purpose of this review is to discuss the anatomy, function, pathology, clinical manifestation, physical examination, imaging and treatment of disorders of the LHBT.
Two- and three-dimensional analyses of translational slides in soils with nonlinear failure envelopes
Authors: Eid Hisham T.
Published: April 2010

This paper aims to assess the effect of nonlinearity of the soil shear strength envelope on the sliding mass configurations and the minimum two- and three-dimensional factors of safety for slopes susceptible to translational failure in both static and seismic conditions. An extensive parametric study was conducted using slope models and nonlinear soil strength envelopes that simulate translational failure case histories. Analysis of the results led to the development of stability charts that do not require an iterative procedure when determining the factors of safety. The introduction of a two-dimensional stability number and three-dimensional stability function, the values of which depend on the degrees of nonlinearity of the involved soils’ strength envelopes, has made it possible to develop such charts. These charts give the practicing geotechnical engineer a reliable and fast method to analyze translational failures. Using available software in such an analysis can be complicated if shear resistance along the sliding mass vertical sides and nonlinearity of soil shear strength envelopes are considered. Numerical examples and a case history are given to verify the reliability and illustrate the different applications of these charts.
FERMIONIC DUAL OF ONE-DIMENSIONAL BOSONIC PARTICLES WITH DERIVATIVE DELTA FUNCTION POTENTIAL
Authors: BASU-MALLICK B. , BHATTACHARYYA TANAYA
Published: April 2010

We investigate the boson–fermion duality relation for the case of quantum integrable derivative δ-function Bose gas. In particular, we find a dual fermionic system with nonvanishing zero-range interaction for the simplest case of two bosonic particles with derivative δ-function interaction. The coupling constant of this dual fermionic system becomes inversely proportional to the product of the coupling constant of its bosonic counterpart and the center-of-mass momentum of the corresponding eigenfunction.
ON THE EFFECTS OF THE NEUMANN BOUNDARY CONDITIONS IN THE COLEMAN–WEINBERG MECHANISM
Authors: FAGUNDES F. N. , OAKES T. L. ANTONACCI , DILEM B. B. , NOGUEIRA J. A.
Published: April 2010

We investigate the effects of the homogeneous Neumann boundary conditions in the scalar electrodynamics with self-interaction. We show that if the length of the finite region is small enough ([Formula: see text], where Mϕ is the mass of the scalar field generated by the Coleman–Weinberg mechanism) the spontaneous symmetry breaking will not be induced and the vector field will not develop mass, however the scalar field will.
EXPLORING TECHNOLOGY DIFFUSION: CASE OF INFORMATION TECHNOLOGIES
Authors: TANOGLU ILDA , BASOGLU NURI , DAIM TUGRUL
Published: April 2010

In today's rapidly changing competitive environment, Information Technology (IT) within an organization is continuously improved, driven by the external push of technological advances and internal pull of increasing organizational needs. In order to achieve the greatest return on IT investment, the diffusion process of IT within the organization should be examined carefully. This study aims to explore the effects of organizational, social, individual, and technological characteristics on the diffusion of different information technologies within organizations, and to discover the relationship between the diffusion of these technologies and the effectiveness, efficiency, and productivity of managerial decision-making processes. Based on a thorough review of theoretical background and prior empirical studies in the area, an integrated research framework concerning the IT diffusion context has been developed and tested via a survey applied on individuals from different organizations. Findings suggest that the antecedents of the diffusion and infusion patterns vary for two major categories of information technologies.
FUNCTIONS WITH SPLINE SPECTRA AND THEIR APPLICATIONS
Authors: CHEN QIUHUI , MICCHELLI CHARLES A. , WANG YI
Published: April 2010

In this paper, we introduce a family of real-valued functions which have spline spectra. They extend the well-known Sinc function and generally are the restrictions to the real line of analytic functions in a strip containing the real axis. We investigate various properties of these functions including those related to interpolation, orthogonality, and stability. Moreover, a sampling formula is provided for their construction and some applications for signal analysis are given.
DISTRIBUTED MULTIRESOLUTION DISCRETE FOURIER TRANSFORM AND ITS APPLICATION TO WATERMARKING
Authors: BHATNAGAR GAURAV , RAMAN BALASUBRAMANIAN
Published: April 2010

The Fourier transform is undoubtedly one of the most valuable and frequently used tools in signal processing and analysis but it has some limitations. In this paper, we rectify these limitations by proposing a newer version of Fourier transform, namely, Distributed Multiresolution Discrete Fourier Transform (D-MR-DFT) and its application in digital watermarking. The core idea of the proposed watermarking scheme is to decompose an image into four frequency sub-bands using D-MR-DFT and then singular values of every sub-band are modified with the singular values of the watermark. The experimental results show better visual imperceptibility and resiliency of the proposed scheme against intentional or unintentional variety of attacks.
WEAK LFM SIGNAL DECTECTION BASED ON WAVELET TRANSFORM MODULUS MAXIMA DENOISING AND OTHER TECHNIQUES
Authors: LE BO , LIU ZHONG , GU TIANXIANG
Published: April 2010

A new method for detecting weak linear frequency modulated (LFM) pulse signals buried in additive white Gaussian noise (AWGN) is presented in this paper. The method is based on the features of wavelet transform modulus maxima (WTMM) denoising and auto-correlation filtering theory. Firstly, the frequency-domain information is extracted by auto-correlation matched filtering, and is used to deduce the optimal wavelet decomposition scales. Secondly, let the signal modulus dominate on the biggest scale after the optimal scales decomposition, then keeping the signal modulus and removing the noise modulus at each scale are performed by utilizing the different propagation properties of signal and noise wavelet modulus maxima across the scales. Finally, a reconstructed signal is obtained from the reserved signal modulus with an improved signal-to-noise ratio (SNR), and is used for time-domain information extraction. At the same time, wavelet denoising depends on selecting an optimum wavelet that matches well the shape of the signal. The cross correlation coefficients between signal and db wavelets are calculated and the optimal wavelet to analysis the LFM signal is selected. Simulations show that the method can extract time-frequency information of LFM signal when SNR ≤ -6 dB .
CYCLIC SYSTEMS OF SIMULTANEOUS CONGRUENCES
Authors: LAGARIAS JEFFREY C.
Published: April 2010

This paper considers the cyclic system of n ≥ 2 simultaneous congruences [Formula: see text] for fixed nonzero integers (r, s) with r > 0 and (r, s) = 1. It shows there are only finitely many solutions in positive integers qi ≥ 2, with gcd (q1q2 ⋯ qn, s) = 1 and obtains sharp bounds on the maximal size of solutions for almost all (r, s). The extremal solutions for r = s = 1 are related to Sylvester's sequence 2, 3, 7, 43, 1807,…. If the positivity condition on the integers qi is dropped, then for r = 1 these systems of congruences, taken ( mod |qi|), have infinitely many solutions, while for r ≥ 2 they have finitely many solutions. The problem is reduced to studying integer solutions of the family of Diophantine equations [Formula: see text] depending on three parameters (r, s, m).
A BIJECTIVE PROOF OF THE QUINTUPLE PRODUCT IDENTITY
Authors: KIM SUN
Published: April 2010

We give a bijective proof of the quintuple product identity using bijective proofs of Jacobi's triple product identity and Euler's recurrence relation.
LOW-DIMENSIONAL STRONGLY PERFECT LATTICES. III: DUAL STRONGLY PERFECT LATTICES OF DIMENSION 14
Authors: NEBE GABRIELE , VENKOV BORIS
Published: April 2010

A lattice is called dual strongly perfect if both, the lattice and its dual, are strongly perfect. We show that the extremal 3-modular lattice [± G2(3)]14 with automorphism group C2 × G2(𝔽3) is the unique dual strongly perfect lattice of dimension 14.
Fast string sorting using order-preserving compression
Authors: López-Ortiz Alejandro , Mirzazadeh Mehdi , Safari Mohammad Ali , Sheikhattar Hossein
Published: April 2010

We give experimental evidence for the benefits of order-preserving compression in sorting algorithms. While, in general, any algorithm might benefit from compressed data because of reduced paging requirements, we identified two natural candidates that would further benefit from order-preserving compression, namely string-oriented sorting algorithms and word-RAM algorithms for keys of bounded length. The word-RAM model has some of the fastest known sorting algorithms in practice. These algorithms are designed for keys of bounded length, usually 32 or 64 bits, which limits their direct applicability for strings. One possibility is to use an order-preserving compression scheme, so that a bounded-key-length algorithm can be applied. For the case of standard algorithms, we took what is considered to be the among the fastest nonword RAM string sorting algorithms, Fast MKQSort, and measured its performance on compressed data. The Fast MKQSort algorithm of Bentley and Sedgewick is optimized to handle text strings. Our experiments show that order-compression techniques results in savings of approximately 15% over the same algorithm on noncompressed data. For the word-RAM, we modified Andersson's sorting algorithm to handle variable-length keys. The resulting algorithm is faster than the standard Unix sort by a factor of 1.5
X
. Last, we used an order-preserving scheme that is within a constant additive term of the optimal Hu--Tucker, but requires linear time rather than
O
(
m
log
m
), where
m
= |Σ| is the size of the alphabet.
Implementing approximation algorithms for the single-source unsplittable flow problem
Authors: Du Jingde , Kolliopoulos Stavros G.
Published: April 2010

In the
single-source unsplittable flow
problem, commodities must be routed simultaneously from a common source vertex to certain sinks in a given graph with edge capacities. The demand of each commodity must be routed along a single path so that the total flow through any edge is at most, its capacity. This problem was introduced by Kleinberg [1996a] and generalizes several NP-complete problems. A cost value per unit of flow may also be defined for every edge. In this paper, we implement the 2-approximation algorithm of Dinitz et al. [1999] for congestion, which is the best known, and the (3, 1)-approximation algorithm of Skutella [2002] for congestion and cost, which is the best known bicriteria approximation. We experimentally study the quality of approximation achieved by the algorithms and the effect of heuristics on their performance. We also compare these algorithms against the previous best ones by Kolliopoulos and Stein [1999].
Improving the performance of multidimensional search using fingers
Authors: Duch Amalia , Martínez Conrado
Published: April 2010

We propose two variants of
K
-d trees where
fingers
are used to improve the performance of orthogonal range search and nearest neighbor queries when they exhibit locality of reference. The experiments show that the second alternative yields significant savings. Although it yields more modest improvements, the first variant does it with much less memory requirements and great simplicity, which makes it more attractive on practical grounds.
Heuristics for estimating contact area of supports in layered manufacturing
Authors: Ilinkin Ivayio , Janardan Ravi , Smid Michiel , Johnson Eric , Castillo Paul , Schwerdt Jörg
Published: April 2010

Layered manufacturing is a technology that allows physical prototypes of three-dimensional(3D) models to be built directly from their digital representation, as a stack of two-dimensional(2D) layers. A key design problem here is the choice of a suitable direction in which the digital model should be oriented and built so as to minimize the area of contact between the prototype and temporary support structures that are generated during the build. Devising an efficient algorithm for computing such a direction has remained a difficult problem for quite some time. In this paper, a suite of efficient and practical heuristics is presented for estimating the minimum contact area. Also given is a technique for evaluating the quality of the estimate provided by any heuristic, which does not require knowledge of the (unknown and hard-to-compute) optimal solution; instead, it provides an indirect upper bound on the quality of the estimate via two relatively easy-to-compute quantities. The algorithms are based on various techniques from computational geometry, such as ray-shooting, convex hulls, boolean operations on polygons, and spherical arrangements, and have been implemented and tested. Experimental results on a wide range of real-world models show that the heuristics perform quite well in practice.
A faster branch-and-bound algorithm for the test-cover problem based on set-covering techniques
Authors: Fahle Torsten , Tiemann Karsten
Published: April 2010

The test-cover problem asks for the minimal number of tests needed to uniquely identify a disease, infection, etc. A collection of branch-and-bound algorithms was proposed by De Bontridder et al. [2002]. Based on their work, we introduce several improvements that are compatible with all techniques described in De Bontridder et al. [2002] and the more general setting of
weighted
test-cover problems. We present a faster data structure, cost-based variable fixing, and adapt well-known set-covering techniques, including Lagrangian relaxation and upper-bound heuristics. The resulting algorithm solves benchmark instances up to 10 times faster than the former approach and up to 100 times faster than a general MIP solver.
A framework for probabilistic numerical evaluation of sensor networks
Authors: Leone Pierre , Rolim Jose , Albuquerque Paul , Mazza Christian
Published: April 2010

In this paper we show how to use stochastic estimation methods to investigate topological properties of sensor networks as well as the behavior of dynamical processes on these networks. The framework is particularly important to study problems for which no theoretical results are known, or cannot be directly applied in practice, for instance, when only asymptotic results are available. We also interpret Russo's formula in the context of sensor networks and thus obtain practical information on their reliability. As a case study, we analyze a localization protocol for wireless sensor networks and validate our approach by numerical experiments. Finally, we mention three applications of our approach: estimating the number of pivotal sensors in a real network, minimizing the number of such sensors for robustness purposes during the network design and estimating the distance between successive localized positions for mobile sensor networks.
Rectangle covers revisited computationally
Authors: Heinrich-Litan Laura , Lübbecke Marco E.
Published: April 2010

We consider the problem of covering an orthogonal polygon with a minimum number of axis-parallel rectangles from a computational point of view. We propose an integer program which is the first general approach to obtain provably optimal solutions to this well-studied NP-hard problem. It applies to common variants like covering only the corners or the boundary of the polygon and also to the weighted case. In experiments, it turns out that the linear programming relaxation is extremely tight and rounding a fractional solution is an immediate high-quality heuristic. We obtain excellent experimental results for polygons originating from VLSI design, fax data sheets, black and white images, and for random instances. Making use of the dual linear program, we propose a stronger lower bound on the optimum, namely, the cardinality of a fractional stable set. Furthermore, we outline ideas how to make use of this bound in primal--dual-based algorithms. We give partial results, which make us believe that our proposals have a strong potential to settle the main open problem in the area: To find a constant factor approximation algorithm for the rectangle cover problem.
Integrating coordinated checkpointing and recovery mechanisms into DSM synchronization barriers
Authors: Boukerche Azzedine , De Melo Alba Cristina Magalhaes Alves
Published: April 2010

Distributed shared memory (DSM) creates an abstraction of a physical shared memory that parallel programmers can access. Most recent software DSM systems provide relaxed-memory models that guarantee consistency only at synchronization operations, such as locks and barriers. As the main goal of DSM systems is to provide support for long-term computation-intensive applications, checkpointing and recovery mechanisms are highly desirable. This article presents and evaluates the integration of a coordinated checkpointing mechanism to the barrier primitive that is usually provided with many DSM systems. Our results on some popular benchmarks and a real parallel application show that the overhead introduced during the failure-free execution is often small.
The “real” approximation factor of the MST heuristic for the minimum energy broadcasting
Authors: Flammini Michele , Navarra Alfredo , Perennes Stephane
Published: April 2010

This paper deals with one of the most studied problems in the last few years in the field of wireless communication in ad-hoc networks. The problem consists of reducing the total energy consumption of wireless radio stations distributed over a given area of interest in order to perform the basic pattern of communication by a broadcast. Recently, a tight 6-approximation of the minimum spanning tree heuristic has been proven. While such a bound is theoretically optimal if compared to the known lower bound of 6, there is an obvious gap with practical experimental results. By extensive experiments, proposing a new technique to generate input instances and supported by theoretical results, we show how the approximation ratio can be actually considered close to 4 for a “real-world” set of instances. We consider, in fact, instances more representative of common practices. Those are usually composed by considerable number of nodes uniformly and randomly distributed inside the area of interest.
A general buffer scheme for the windows scheduling problem
Authors: Bar-Noy Amotz , Ladner Richard E. , Christensen Jacob , Tamir Tami
Published: April 2010

Broadcasting is an efficient alternative to unicast for delivering popular on-demand media requests. Broadcasting schemes that are based on windows scheduling algorithms provide a way to satisfy all requests with both low bandwidth and low latency.

Consider a system of
n
pages that need to be scheduled (transmitted) on identical channels an infinite number of times. Time is slotted, and it takes one time slot to transmit each page. In the
windows scheduling problem
(WS) each page
i
, 1 ≤
i
≤
n
, is associated with a

request window w
i

. In a feasible schedule for WS, page
i
must be scheduled at least once in any window of

w
i

time slots. The objective function is to minimize the number of channels required to schedule all the pages.

The main contribution of this paper is the design of a general
buffer scheme
for the windows scheduling problem such that
any
algorithm for WS follows this scheme. As a result, this scheme can serve as a tool to analyze and/or exhaust all possible WS-algorithms.

The buffer scheme is based on modelling the system as a nondeterministic finite state machine in which any directed cycle corresponds to a legal schedule and vice-versa. Since WS is NP-hard, we present some heuristics and pruning-rules for cycle detection that ensure reasonable cycle-search time.

By introducing various rules, the buffer scheme can be transformed into deterministic scheduling algorithms. We show that a simple page-selection rule for the buffer scheme provides an optimal schedule to WS for the case where all the

w
i

's have divisible sizes, and other good schedules for some other general cases. By using an exhaustive-search, we prove impossibility results for other important instances.

We also show how to extend the buffer scheme to more generalized environments in which (
i
) pages are arriving and departing on-line, (
ii
) the window constraint has some
jitter
, and (
iii
) different pages might have different lengths.
Fast computation of empirically tight bounds for the diameter of massive graphs
Authors: Magnien Clémence , Latapy Matthieu , Habib Michel
Published: April 2010

The diameter of a graph is among its most basic parameters. Since a few years ago, it moreover became a key issue to compute it for massive graphs in the context of complex network analysis. However, known algorithms, including the ones producing approximate values, have too high a time and/or space complexity to be used in such cases. We propose here a new approach relying on very simple and fast algorithms that compute (upper and lower) bounds for the diameter. We show empirically that, on various real-world cases representative of complex networks studied in the literature, the obtained bounds are very tight (and even equal in some cases). This leads to rigorous and very accurate estimations of the actual diameter in cases which were previously untractable in practice.
How much geometry it takes to reconstruct a 2-manifold in R
3
Authors: Dumitriu Daniel , Funke Stefan , Kutz Martin , Milosavljević Nikola
Published: April 2010

Known algorithms for reconstructing a 2-manifold from a point sample in R
3
are naturally based on decisions/predicates that take the geometry of the point sample into account. Facing the always present problem of round-off errors that easily compromise the exactness of those predicate decisions, an exact and robust implementation of these algorithms is far from being trivial and typically requires employment of advanced datatypes for exact arithmetic, as provided by libraries like CORE, LEDA, or GMP. In this article, we present a new reconstruction algorithm, one whose main novelties is to throw away geometry information early on in the reconstruction process and to mainly operate combinatorially on a graph structure. More precisely, our algorithm only requires
distances
between the sample points and not the actual embedding in R
3
. As such, it is less susceptible to robustness problems due to round-off errors and also benefits from not requiring expensive exact arithmetic by faster running times. A more theoretical view on our algorithm including correctness proofs under suitable sampling conditions can be found in a companion article.
Experimental study of geometric
t
-spanners
Authors: Farshi Mohammad , Gudmundsson Joachim
Published: April 2010

The construction of
t
-spanners of a given point set has received a lot of attention, especially from a theoretical perspective. In this article, we experimentally study the performance and quality of the most common construction algorithms for points in the Euclidean plane. We implemented the most well-known
t
-spanner algorithms and tested them on a number of different point sets. The experiments are discussed and compared to the theoretical results, and in several cases, we suggest modifications that are implemented and evaluated. The measures of quality that we consider are the number of edges, the weight, the maximum degree, the spanner diameter, and the number of crossings. This is the first time an extensive comparison has been made between the running times of construction algorithms of
t
-spanners and the quality of the generated spanners.
Dynamic trees in practice
Authors: Tarjan Robert E. , Werneck Renato F.
Published: April 2010

Dynamic tree data structures maintain forests that change over time through edge insertions and deletions. Besides maintaining connectivity information in logarithmic time, they can support aggregation of information over paths, trees, or both. We perform an experimental comparison of several versions of dynamic trees: ST-trees, ET-trees, RC-trees, and two variants of top trees (self-adjusting and worst-case). We quantify their strengths and weaknesses through tests with various workloads, most stemming from practical applications. We observe that a simple, linear-time implementation is remarkably fast for graphs of small diameter, and that worst-case and randomized data structures are best when queries are very frequent. The best overall performance, however, is achieved by self-adjusting ST-trees.
Software cost estimation using fuzzy logic
Authors: Mittal Anish , Parkash Kamal , Mittal Harish
Published: April 2010

Effective Software cost estimation is one of the most challenging and important activities in Software development. The software industry does not estimate projects well. In this paper we have represented size in KLOC as a Fuzzy number. A new model is presented using fuzzy logic to estimate effort required in software development. We use MATLAB for tuning the parameters of famous COCOMO model. The performance of model is evaluated on published software projects data. Comparison of results from our model with existing prevalent models is done.
Estimation of software reusability
Authors: Nair T.R. Gopalakrishnan , Selvarani R.
Published: April 2010

In this paper an effective estimation model is proposed for software reusability. The structural properties of the software are analyzed at design level with an engineering approach. This leads to the analysis of intricate relationship existing between the reusability and the design properties. An estimation model is created based on the empirical studies and weighted combination of polynomials using CK meas-ures.
NCQ vs. I/O scheduler
Authors: Yu Young Jin , Shin Dong In , Eom Hyeonsang , Yeom Heon Young
Published: April 2010

Native Command Queueing (NCQ) is an optimization technology to maximize throughput by reordering requests inside a disk drive. It has been so successful that NCQ has become the standard in SATA 2 protocol specification, and the great majority of disk vendors have adopted it for their recent disks. However, there is a possibility that the technology may lead to an information gap between the OS and a disk drive. A NCQ-enabled disk tries to optimize throughput without realizing the intention of an OS, whereas the OS does its best under the assumption that the disk will do as it is told without specific knowledge regarding the details of the disk mechanism. Let us call this
expectation discord
, which may cause serious problems such as request starvations or performance anomaly. In this article, we (1) confirm that
expectation discord
actually occurs in real systems; (2) propose software-level approaches to solve them; and (3) evaluate our mechanism. Experimental results show that our solution is simple, cheap (no special hardware required), portable, and effective.
FRASH
Authors: Jung Jaemin , Won Youjip , Kim Eunki , Shin Hyungjong , Jeon Byeonggil
Published: April 2010

In this work, we develop a novel hybrid file system, FRASH, for storage-class memory and NAND Flash. Despite the promising physical characteristics of storage-class memory, its scale is an order of magnitude smaller than the current storage device scale. This fact makes it less than desirable for use as an independent storage device. We carefully analyze in-memory and on-disk file system objects in a log-structured file system, and exploit memory and storage aspects of the storage-class memory to overcome the drawbacks of the current log-structured file system. FRASH provides a hybrid view storage-class memory. It harbors an in-memory data structure as well as a on-disk structure. It provides nonvolatility to key data structures which have been maintained in-memory in a legacy log-structured file system. This approach greatly improves the mount latency and effectively resolves the robustness issue. By maintaining on-disk structure in storage-class memory, FRASH provides byte-addressability to the file system object and metadata for page, and subsequently greatly improves the I/O performance compared to the legacy log-structured approach. While storage-class memory offers byte granularity, it is still far slower than its DRAM counter part. We develop a copy-on-mount technique to overcome the access latency difference between main memory and storage-class memory. Our file system was able to reduce the mount time by 92% and file system I/O performance was increased by 16%.
A self-adjusting flash translation layer for resource-limited embedded systems
Authors: Wu Chin-Hsien
Published: April 2010

The capacity of flash memory storage systems has been growing at a speed similar to many other storage systems. In order to properly manage the product cost, vendors face serious challenges in resource-limited embedded systems. In this article, a self-adjusting flash translation layer is proposed with low memory requirements. The objective of the design is to provide efficient address mapping and low garbage collection overhead, while controlling main memory usage of the flash translation layer. The capability of the design is evaluated over realistic workloads and benchmarks. System performance is also guaranteed under low memory requirements.
GUSTO
Authors: Irturk Ali , Benson Bridget , Mirzaei Shahnam , Kastner Ryan
Published: April 2010

Matrix inversion is a common function found in many algorithms used in wireless communication systems. As FPGAs become an increasingly attractive platform for wireless communication, it is important to understand the trade-offs in designing a matrix inversion core on an FPGA. This article describes a matrix inversion core generator tool, GUSTO, that we developed to ease the design space exploration across different matrix inversion architectures. GUSTO is the first tool of its kind to provide automatic generation of a variety of general-purpose matrix inversion architectures with different parameterization options. GUSTO also provides an optimized application-specific architecture with an average of 59% area decrease and 3X throughput increase over its general-purpose architecture. The optimized architectures generated by GUSTO provide comparable results to published matrix inversion architecture implementations, but offer the advantage of providing the designer the ability to study the trade-offs between architectures with different design parameters.
System and software architectures of distributed smart cameras
Authors: Lin Chang Hong , Wolf Marilyn , Koutsoukos Xenefon , Neema Sandeep , Sztipanovits Janos
Published: April 2010

In this article, we describe a distributed, peer-to-peer gesture recognition system along with a software architecture modeling technique and authority control protocol for ubiquitous cameras. This system performs gesture recognition in real time by combining imagery from multiple cameras without using a central server. We propose a system architecture that uses a network of inexpensive cameras to perform in-network video processing. A methodology for transforming well-designed single-node algorithm to distributed system is also proposed. Applications for ubiquitous cameras can be modeled as the composition of a finite-state machine of the system, functional services, and middleware. A service-oriented software architecture is proposed to dynamically reconfigure services when system state changes. By exchanging data and control messages between neighboring sensors, each node can maintain broader view of the environment with integrated video-processing results. Our prototype system is built on Windows machines, and uses standard video cameras as sensors and local network as a communication channel.
A multifrequency MAC specially designed for wireless sensor network applications
Authors: Zhou Gang , Wu Yafeng , Yan Ting , He Tian , Huang Chengdu , Stankovic John A. , Abdelzaher Tarek F.
Published: April 2010

Multifrequency media access control has been well understood in general wireless ad hoc networks, while in wireless sensor networks, researchers still focus on single frequency solutions. In wireless sensor networks, each device is typically equipped with a single radio transceiver and applications adopt much smaller packet sizes compared to those in general wireless ad hoc networks. Hence, the multifrequency MAC protocols proposed for general wireless ad hoc networks are not suitable for wireless sensor network applications, which we further demonstrate through our simulation experiments. In this article, we propose MMSN, which takes advantage of multifrequency availability while, at the same time, takes into consideration the restrictions of wireless sensor networks. In MMSN, four frequency assignment options are provided to meet different application requirements. A scalable media access is designed with efficient broadcast support. Also, an optimal nonuniform back-off algorithm is derived and its lightweight approximation is implemented in MMSN, which significantly reduces congestion in the time synchronized media access design. Through extensive experiments, MMSN exhibits the prominent ability to utilize parallel transmissions among neighboring nodes. When multiple physical frequencies are available, it also achieves increased energy efficiency, demonstrating the ability to work against radio interference and the tolerance to a wide range of measured time synchronization errors.
Microsearch
Authors: Tan Chiu C. , Sheng Bo , Wang Haodong , Li Qun
Published: April 2010

In this article, we present Microsearch, a search system suitable for embedded devices used in ubiquitous computing environments. Akin to a desktop search engine, Microsearch indexes the information inside a small device, and accurately resolves a user's queries. Given the limited hardware, conventional search engine design and algorithms cannot be used. We adopt Information Retrieval (IR) techniques for query resolution, and proposed a new space-efficient top-
k
query resolution algorithm. A theoretical model of Microsearch is given to better understand the trade-offs in design parameters. Evaluation is done via actual implementation on off-the-shelf hardware.
Efficient algorithms for the 2-gathering problem
Authors: Shalita Alon , Zwick Uri
Published: April 2010

Pebbles are placed on some vertices of a directed graph. Is it possible to move each pebble along at most one edge of the graph so that in the final configuration no pebble is left on its own? We give an
O
(
mn
)-time algorithm for solving this problem, which we call the
2-gathering
problem, where
n
is the number of vertices and
m
is the number of edges of the graph. If such a 2-gathering is not possible, the algorithm finds a solution that minimizes the number of solitary pebbles. The 2-gathering problem forms a nontrivial generalization of the nonbipartite matching problem and it is solved by extending the augmenting paths technique used to solve matching problems.
One Laptop per Child
Authors: Purington David
Published: April 2010

The age-old adage "Give a man a fish; he'll eat for a day. Teach a man to fish he'll eat for the rest of his days", has truly manifested itself in Nicholas Negroponte's One Laptop per Child program. His organization seeks "To create educational opportunities for the world's poorest children by providing each child with a rugged, low-cost, low-power, connected laptop with content and software designed for collaborative, joyful, self-empowered learning" (OLPC Mission Statement). While it is seemingly a noble humanitarian effort for the enhancement of education, support for the "$100 laptop" has fallen short of its stated goal with only twenty-eight participating countries. The fact that only a limited number of countries are willing to enter the program demonstrates that it does not address the majority of problems faced by developing nations. Inadequate education is one of many pressing social concerns, but its necessity should not be placed above the immediate needs of developing nations. And for an organization devoted to a non-survival-essential cause to pursue such an ambitious objective brings its social significance and ethics under question.
Reconfiguring a state machine
Authors: Lamport Leslie , Malkhi Dahlia , Zhou Lidong
Published: April 2010

Reconfiguration means changing the set of processes executing a distributed system. We explain several methods for reconfiguring a system implemented using the state-machine approach, including some new ones. We discuss the relation between these methods and earlier reconfiguration algorithms--especially view changing in group communication.
Enhanced transforming growth factor-β signaling and fibrogenesis in ovine fetal skeletal muscle of obese dams at late gestation
Authors: Huang Yan , Yan Xu , Zhu Mei J. , McCormick Richard J. , Ford Stephen P. , Nathanielsz Peter W. , Du Min
Published: April 2010

Maternal obesity (MO) is increasing at an alarming rate. The objective of this study was to evaluate the effect of MO on fibrogenesis in fetal skeletal muscle during maturation in late gestation. Nonpregnant ewes were assigned to a control diet (Con; fed 100% of NRC nutrient recommendations, n = 6) or obesogenic diet (OB; fed 150% of NRC recommendations, n = 6) from 60 days before conception, and fetal semitendenosus (St) muscle was sampled at 135 days of gestation (term 148 days). Total concentration and area of collagen in cross-sections of muscle increased by 27.0 ± 6.0 ( P < 0.05) and 105.1 ± 5.9% ( P = 0.05) in OB compared with Con fetuses. The expression of precursor TGF-β was 177.3 ± 47.6% higher, and concentration of phospho-p38 74.7 ± 23.6% was higher ( P < 0.05) in OB than in CON fetal muscle. Increases of 327.9 ± 168.0 ( P < 0.05) and 188.9 ± 82.1% ( P < 0.05), respectively, were observed for mRNA expression of Smad7 and fibronectin in OB compared with Con muscles. In addition, enzymes involved in collagen synthesis, including lysyl oxidase, lysyl hydroxylase 2b, and prolyl 4-hydroxylase-α1, were increased by 350.2 ± 90.0 ( P < 0.05), 236.5 ± 25.2 ( P < 0.05), and 82.0 ± 36.2% ( P = 0.05), respectively, in OB muscle. In conclusion, MO-enhanced fibrogenesis in fetal muscle in late gestation was associated with upregulation of the TGF-β/p38 signaling pathway. Enhanced fibrogenesis at such an early stage of development is expected to negatively affect the properties of offspring muscle because muscle fibrosis is a hallmark of aging.
PGC-1α regulation by exercise training and its influences on muscle function and insulin sensitivity
Authors: Lira Vitor A. , Benton Carley R. , Yan Zhen , Bonen Arend
Published: April 2010

The peroxisome proliferator-activated receptor-γ (PPARγ) coactivator-1α (PGC-1α) is a major regulator of exercise-induced phenotypic adaptation and substrate utilization. We provide an overview of 1) the role of PGC-1α in exercise-mediated muscle adaptation and 2) the possible insulin-sensitizing role of PGC-1α. To these ends, the following questions are addressed. 1) How is PGC-1α regulated, 2) what adaptations are indeed dependent on PGC-1α action, 3) is PGC-1α altered in insulin resistance, and 4) are PGC-1α-knockout and -transgenic mice suitable models for examining therapeutic potential of this coactivator? In skeletal muscle, an orchestrated signaling network, including Ca2+-dependent pathways, reactive oxygen species (ROS), nitric oxide (NO), AMP-dependent protein kinase (AMPK), and p38 MAPK, is involved in the control of contractile protein expression, angiogenesis, mitochondrial biogenesis, and other adaptations. However, the p38γ MAPK/PGC-1α regulatory axis has been confirmed to be required for exercise-induced angiogenesis and mitochondrial biogenesis but not for fiber type transformation. With respect to a potential insulin-sensitizing role of PGC-1α, human studies on type 2 diabetes suggest that PGC-1α and its target genes are only modestly downregulated (≤34%). However, studies in PGC-1α-knockout or PGC-1α-transgenic mice have provided unexpected anomalies, which appear to suggest that PGC-1α does not have an insulin-sensitizing role. In contrast, a modest (∼25%) upregulation of PGC-1α, within physiological limits, does improve mitochondrial biogenesis, fatty acid oxidation, and insulin sensitivity in healthy and insulin-resistant skeletal muscle. Taken altogether, there is substantial evidence that the p38γ MAPK-PGC-1α regulatory axis is critical for exercise-induced metabolic adaptations in skeletal muscle, and strategies that upregulate PGC-1α, within physiological limits, have revealed its insulin-sensitizing effects.
Epithelial repair mechanisms in the lung
Authors: Crosby Lynn M. , Waters Christopher M.
Published: April 2010

The recovery of an intact epithelium following lung injury is critical for restoration of lung homeostasis. The initial processes following injury include an acute inflammatory response, recruitment of immune cells, and epithelial cell spreading and migration upon an autologously secreted provisional matrix. Injury causes the release of factors that contribute to repair mechanisms including members of the epidermal growth factor and fibroblast growth factor families (TGF-α, KGF, HGF), chemokines (MCP-1), interleukins (IL-1β, IL-2, IL-4, IL-13), and prostaglandins (PGE2), for example. These factors coordinate processes involving integrins, matrix materials (fibronectin, collagen, laminin), matrix metalloproteinases (MMP-1, MMP-7, MMP-9), focal adhesions, and cytoskeletal structures to promote cell spreading and migration. Several key signaling pathways are important in regulating these processes, including sonic hedgehog, Rho GTPases, MAP kinase pathways, STAT3, and Wnt. Changes in mechanical forces may also affect these pathways. Both localized and distal progenitor stem cells are recruited into the injured area, and proliferation and phenotypic differentiation of these cells leads to recovery of epithelial function. Persistent injury may contribute to the pathology of diseases such as asthma, chronic obstructive pulmonary disease, and pulmonary fibrosis. For example, dysregulated repair processes involving TGF-β and epithelial-mesenchymal transition may lead to fibrosis. This review focuses on the processes of epithelial restitution, the localization and role of epithelial progenitor stem cells, the initiating factors involved in repair, and the signaling pathways involved in these processes.