bluuebunny/crossref_metadata_2025 huggingface dataset:
2′, 3′‐cyclic nucleotide 3′‐phosphodiesterase cells derived from transplanted marrow stromal cells and host tissue contribute to perineurial compartment formation in injured rat spinal cord
Authors: Cao Qiong , Ding Peng , Lu Jia , Dheen S. Thameem , Moochhala Shabbir , Ling Eng‐Ang
Published: October 2006

Transdifferentiation of transplanted marrow stromal cells (MSCs) and reactive changes of glial cells in a completely transected rat spinal cord were examined. Marrow stromal cells exhibited 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase (CNP) at the plasma membrane and this has allowed their identification after transplantation by immunoelectron microscopy. In the control rats, the lesion site showed activated microglia/neural macrophages and some elongated cells, whose cytoplasm was immunoreactive for CNP. Cells designated as CNP1 and apparently host‐derived expressed CXCR4. In experimental rats receiving MSCs transplantation, CNP1 cells were increased noticeably. This was coupled with the occurrence of a different subset of CNP cells whose plasma membrane was CNP‐immunoreactive and expressed CXCR4. These cells, designated as CNP2, enclosed both myelinated and unmyelinated neurites thus assuming a spatial configuration resembling that of Schwann cells. A remarkable feature was the extensive ramifications of CNP1 cells with long filopodia processes delineating the CNP2 cells and their associated neurites, forming many perineurial‐like compartments. Present results have shown that CNP2 cells considered to be MSCs‐derived can transform into cells resembling Schwann cells based on their spatial relation with the regenerating nerve fibers, whereas the CNP1 glial cells participate in formation of perineurial compartments, probably serving as conduits to guide the nerve fiber growth. The chemotactic migration of CNP cells either derived from host tissue or MSCs bearing CXCR4 may be attracted by stromal derived factor‐1α (SDF‐1α) produced locally. The coordinated cellular interaction between transplanted MSCs and local glial cells may promote the growth of nerve fibers through the lesion site. © 2006 Wiley‐Liss, Inc.
Neurocognitive effects of treatment for childhood cancer
Authors: Butler Robert W. , Haser Jennifer K.
Published: October 2006

We review research on the neuropsychological effects that central nervous system (CNS) cancer treatments have on the cognitive abilities of children and adolescents. The authors focus on the two most common malignancies of childhood: leukemias and brain tumors. The literature review is structured so as to separate out earlier studies, generally those published prior to 1995, as opposed to manuscripts that have been published within the past decade. This is an important distinction for both leukemia and brain tumors. Earlier studies were ground breaking in that they began to map out what could be expected in terms of intelligence and academic problems in survivors of pediatric malignancies. Survivorship in this population has and continues to markedly increase and this is largely due to changes in treatment protocols. Research on neurocognitive effects of disease and treatment in pediatric oncology has become increasingly sophisticated, and this literature review not only reflects this trend, but highlights the growing collaboration between neuropsychology, cognitive neuroscience, and neuro‐imaging. Thus, our goal was to provide a historical foundation, lead the reader towards the progression of research methodology up to the current state of the art, and perhaps most importantly, discuss future directions. These directions are especially relevant to the concepts of remediation and treatment of cognitive problems, and this is emphasized at the conclusion of the review. MRDD Research Reviews 2006;12:184–191. © 2006 Wiley‐Liss, Inc.
Sickle cell disease as a neurodevelopmental disorder
Authors: Schatz Jeffrey , McClellan Catherine B.
Published: October 2006

Sickle cell disease (SCD) is a blood disorder; however, the central nervous system (CNS) is one of the organs frequently affected by the disease. Brain disease can begin early in life and often leads to neurocognitive dysfunction. Approximately one‐fourth to one‐third of children with SCD have some form of CNS effects from the disease, which typically manifest as deficits in specific cognitive domains and academic difficulties. We discuss SCD as a neurodevelopmental disorder by reviewing the mechanisms of neurological morbidity in SCD, the timing of these mechanisms, the types of cognitive and behavioral morbidity that is typical, and the interaction of social‐environmental context with disease processes. The impact of the disease on families shares many features similar to other neurodevelopmental disorders; however, social‐environmental factors related to low socioeconomic status, worry and concerns about social stigma, and recurrent, unpredictable medical complications can be sources of relatively higher stress in SCD. Greater public awareness of the neurocognitive effects of SCD and their impact on child outcomes is a critical step toward improved treatment, adaptation to illness, and quality of life. MRDD Research Reviews 2006;12:200–207. © 2006 Wiley‐Liss, Inc.
Effect of cold‐induced stress on rat bladder tissue contractility and histomorphology
Authors: Demir Aslan , Önol Fikret Fatih , Ercan Feriha , Tarcan Tufan
Published: October 2006

Aims

To investigate the effects of cold‐induced stress on bladder tissue histomorphology and contractility in a rat model.

Methods

Eighteen male Sprague–Dawley rats were divided into three groups: Control group (Group 1), acute cold‐stress group (Group 2, kept at +4°C for 8 hr), and chronic cold‐stress group (Group 3, kept at +4°C for 4 hr/day for 21 days). At the end of protocols, histological examination of general bladder tissue morphology and determination of mast cells was performed. Organ bath studies were conducted at basal tone where contractile responses to 120 mM potassium, electrical field stimulation (EFS), and carbachol (10−9–10−4 M) were assessed. Relaxation responses to EFS, isoproterenol (10−9–10−4 M), papaverine plus sodium nitroprusside (10−4 M each) were recorded in carbachol pre‐contracted strips. All data were compared by one‐way ANOVA test.

Results

Group 1 revealed regular bladder mucosa with intact urothelium. Groups 2 and 3 showed degeneration of urothelium with accumulation of neutrophils and significantly increased number of mast cells in both mucosa and muscularis. Mast cell counts were significantly higher in Group 3 compared to Group 2. Contractile responses to 120 mM potassium and EFS were significantly greater in the control group compared to other groups. Carbachol caused dose‐dependent contractions that were significantly higher in the control group (at 10−5, 3 × 10−5, and 10−4 M doses). There was no statistical difference between the groups in terms of relaxation responses.

Conclusions

In vivo cold exposure induces significant bladder injury and decreased tissue contractility. Mechanistic pathways involved in the response of the urinary bladder to cold‐induced stress need further investigation. Neurourol. Urodynam. 26:296–301, 2007. © 2006 Wiley‐Liss, Inc.
A logarithmic‐exponential backward‐Euler‐based split of the flow rule for anisotropic inelastic behaviour at small elastic strain
Authors: Svendsen Bob
Published: October 2006

A basic aspect of modern algorithmic formulations for large‐deformation hyperelastic‐based isotropic inelastic material models is the exponential backward‐Euler form of the algorithmic flow rule in the context of the multiplicative decomposition of the deformation gradient. Advantages of this approach in the isotropic context include the exact algorithmic fulfilment of inelastic incompressibility. The purpose of this short work is to show that such an algorithm can be formulated for anisotropic inelastic models as well under assumption of small elastic strain, i.e. for metals. In particular, the current approach works for both phenomenological anisotropy as well as for crystal plasticity. The major difference between the current and previous approaches lies in the fact that the elastic rotation is reduced algorithmically to a dependent internal variable, resulting in a smaller internal variable system. Copyright © 2006 John Wiley & Sons, Ltd.
A fixed‐mesh Eulerian–Lagrangian approach for stress analysis in continuous casting
Authors: Fachinotti Víctor D. , Cardona Alberto
Published: October 2006

We present a method for the analysis of the strains and stresses developed in the solidified portion of a metal strand during the continuous casting process. Steady‐state conditions are assumed. The solidified metal is modelled as a standard inelastic solid with isotropic hardening and von Mises yield criterion. Constitutive equations are formulated over the material particles (Lagrangian approach) that instantaneously occupy a fixed domain attached to the casting machine, which is discretized (Eulerian approach). Particle tracking, needed to record the deformation history at each fixed sampling point, becomes trivial because of the usual hypothesis of constant and homogeneous advection velocity. Backward‐Euler (implicit) finite differences and mixed finite elements are used for time and spatial discretization, respectively. The resulting non‐linear algebraic equations are solved using the Newton–Raphson method. Copyright © 2006 John Wiley & Sons, Ltd.
Effects of lithium salt and poly(4‐vinyl phenol) on crystalline and amorphous phases in poly(ethylene oxide)
Authors: Lin Jia‐Hsien , Woo E. M. , Huang Yin‐Ping
Published: October 2006

Effects of a strong‐interacting amorphous polymer, poly(4‐vinyl phenol) (PVPh), and an alkali metal salt, lithium perchlorate (LiClO4), on the amorphous and crystalline domains in poly(ethylene oxide) (PEO) were probed by differential scanning calorimetry (DSC), optical microscopy (OM), and Fourier transform infrared spectroscopy (FTIR). Addition of lithium perchlorate (LiClO4, up to 10% of the total mass) led to enhanced Tg's, but did not disturb the miscibility state in the amorphous phase of PEO/PVPh blends, where the salt in the form of lithium cation and ClO anion was well dispersed in the matrix. Competitive interactions between PEO, PVPh, and Li+ and ClO ions were evidenced by the elevation of glass transition temperatures and shifting of IR peaks observed for LiClO4‐doped PEO/PVPh blend system. However, the doping distinctly influenced the crystalline domains of LiClO4‐doped PEO or LiClO4‐doped PEO/PVPh blend system. LiClO4 doping in PEO exerted significant retardation on PEO crystal growth. The growth rates for LiClO4‐doped PEO were order‐of‐magnitude slower than those for the salt‐free neat PEO. Dramatic changes in spherulitic patterns were also seen, in that feather‐like dendritic spherulites are resulted, indicating strong interactions. Introduction of both miscible amorphous PVPh polymer and LiClO4 salt in PEO can potentially be a new approach of designing PEO as matrix materials for electrolytes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3357–3368, 2006
Effective use of differential scanning calorimetry in reactive chemicals hazard evaluation
Authors: Frurip David J. , Elwell Tim
Published: October 2006

DSC (differential scanning calorimetry) is one of the most commonly applied thermal stability testing methodologies in reactive chemicals hazard evaluation. This is certainly because of many factors, including the relative low cost of the equipment, rapid turnaround time of experiments, small sample size, ease of interpretation, relative accuracy of the calorimetric results, and the wide range of temperatures over which a DSC can operate. Traditionally DSC is mainly used as a screening method used to identify possible energy release hazards, which may require further, more sophisticated testing to elucidate and quantify the actual hazard. Practitioners have learned to maximize the information obtainable from DSC testing. This article highlights how DSC is applied to routine day‐to‐day hazard screening and summarizes the collective knowledge of Dow in this area for over 20 years. Some applications discussed include: recognizing thermal events from peak shape, high energy materials, chemical compatibility, and eliminating unnecessary testing. Also presented are examples of the limitations of DSC and examples where it should not be used. Finally, this article discusses how DSC may be used to estimate reaction kinetics by quantitative thermokinetic modeling. © 2006 American Institute of Chemical Engineers Process Saf Prog, 2007
Infant growth modelling using a shape invariant model with random effects
Authors: Beath Ken J.
Published: October 2006

Models for infant growth have usually been based on parametric forms, commonly an exponential or similar model, which have been shown to fit poorly especially during the first year of life. An alternative approach is to use a non‐parametric model, based on a shape invariant model (SIM), where a single function is transformed by shifting and scaling to fit each subject. In the model a regression spline is used as the function, with log transformation of the data and a simplification of the SIM, obtained from the relationship with the exponential model. All subjects are fitted as a nonlinear mixed effects model, allowing the variation in the parameters between subjects to be determined. Methods for the inclusion of covariates in growth models based on SIM are developed, with parameters for time independent covariates included in the model by varying either the shape, the size parameter or the growth parameter and time‐dependent co‐variates included by transforming the time axis, to either increase or decrease the growth rate dependent on the co‐variate, similar to methods used for accelerated failure‐time models. The model is used to fit weight data for 602 infants, measured from 0 to 2 years as part of the Childhood Asthma Prevention Study (CAPS) trial, and to determine the effect of breastfeeding on infant weight. Copyright © 2006 John Wiley & Sons, Ltd.
A comparison of interactivity in the Linux 2.6 scheduler and an MLFQ scheduler
Authors: Torrey Lisa A. , Coleman Joyce , Miller Barton P.
Published: October 2006

We implemented a simple multilevel feedback queue scheduler in the Linux 2.6 kernel and compared its response to interactive tasks with that of the new Linux 2.6 scheduler. Our objectives were to evaluate whether Linux 2.6 accomplished its goal of improved interactivity, and to see whether a simpler model could do as well without all of the special cases and exceptions that the new Linux 2.6 scheduler acquired. We describe the two algorithms in detail, report their average interactive response times under different kinds of background workloads, and compare their methods of deciding whether a task is interactive. The MLFQ scheduler performs comparably to the Linux 2.6 scheduler in all response time tests and displays some inadvertent improvements in turnaround time, while avoiding the complex task of explicitly defining interactivity. We maintain an inverse relationship between priority and time slice length, and this seems to be the primary reason that the MLFQ remains simple, yet performs comparably to the Linux 2.6 scheduler. These results may provide some guidelines for designers of new scheduling systems. Copyright © 2006 John Wiley & Sons, Ltd.
Ablego: a function outlining and partial inlining framework
Authors: Zhao Peng , Amaral José Nelson
Published: October 2006

Frequently invoked large functions are common in non‐numeric applications. These large functions present challenges to modern compilers not only because they require more time and resources at compilation time, but also because they may prevent optimizations such as function inlining. Often large portions of the code in a hot functionfhostare executed much less frequently thanfhostitself. Partial inlining is a natural solution to the problems caused by includingcoldcode segments that are seldom executed intohotfunctions that are frequently invoked. When applying partial inlining, a compileroutlinescold statements from a hot functionfhost. After outlining,fhostbecomes smaller and thus can be easily inlined. This paper presentsAblego, a framework for function outlining and partial inlining that includes several innovations: (1) an abstract‐syntax‐tree‐based analysis and transformation to form cold regions for outlining; (2) a set of flexible heuristics to control the aggressiveness of function outlining; (3) several possible function outlining strategies; (4)explicit variable spilling, a new technique that overcomes negative side‐effects of function outlining. With the proper strategy, partial inlining improves performance by up to 5.75%. A performance study also suggests that partial inlining's effect on enabling more aggressive inlining is limited. The performance improvement from partial inlining actually comes from better code placement and better code generation. Copyright © 2006 John Wiley & Sons, Ltd.
A style for integrating MS‐Windows software applications to client–server systems using Java technology
Authors: Lin Jim‐Min , Hong Zeng‐Wei , Fang Guo‐Ming , Lee Che‐Tai
Published: October 2006

Developing software systems by integrating the existing applications/systems over the network has become an established and practical technique. The Microsoft (MS) Windows operating systems today support a huge number of software applications. If these commercial applications could be transformed to software components, this may accelerate the construction of new components. This paper proposes an architectural style to support a three‐phase process for integrating MS‐Windows applications in a distributed system using Java technologies. This style provides a solution with clear documentation and sufficient information that is helpful for the rapid integration of MS‐Windows applications. Finally, an exemplary graphical construction part management system that assembles two MS‐Windows applications was developed in this study to demonstrate the feasibility of this style. Copyright © 2006 John Wiley & Sons, Ltd.
Autonomic configuration and recovery in a mobile agent‐based distributed event monitoring system
Authors: Tripathi Anand R. , Kulkarni Devdatta , Talkad Harsha , Koka Muralidhar , Karanth Sandeep , Ahmed Tanvir , Osipkov Ivan
Published: October 2006

In this paper we present a framework for building policy‐based autonomic distributed agent systems. The autonomic mechanisms of configuration and recovery are supported through a distributed event processing model and a set of policy enforcement mechanisms embedded in an agent framework. Policies are event‐driven rules derived from the system's functional and non‐functional requirements. Agents in the network monitor the system state for policy violation conditions, generate appropriate events, and communicate them to other agents for cooperative filtering, aggregation, and handling. A set of agents perform policy enforcement actions whenever events signifying any policy violation conditions occur. Policies are defined using a specification framework based on XML. The policy enforcement agents interpret the policies given in XML. We illustrate the utility of this framework in the context of an agent‐based distributed network monitoring application. We also present an experimental evaluation of our approach. Copyright © 2006 John Wiley & Sons, Ltd.
An efficient deletion method for a minimal prefix double array
Authors: Yata Susumu , Oono Masaki , Morita Kazuhiro , Fuketa Masao , Aoe Jun‐ichi
Published: October 2006

A minimal prefix (MP) double array is an efficient data structure for a trie. The MP double array only requires a small amount of space and enables fast retrieval. However, the space efficiency of the MP double array is degraded by deletion. This paper presents a fast and compact adaptive deletion method for the MP double array. The presented method is implemented with C. Simulation results for English and Japanese keys show that the adaptive method is faster than the conventional method and maintains higher space efficiency. Copyright © 2006 John Wiley & Sons, Ltd.
Comparison of clinical outcomes and spectral Doppler indices of uterine and ovarian stromal arteries in women undergoing myomectomy with or without hypogastric arterial ligation
Authors: Fu H.‐C. , Huang K.‐H. , Tseng C.‐W. , Liang H.‐M. , Lin H. , Chou Y.‐J. , Kung F.‐T.
Published: October 2006

Objective

To compare clinical outcomes and hemodynamic alterations of uterine and ovarian stromal arteries between patients with symptomatic myomas undergoing myomectomy preceded by arterial ligation and those undergoing myomectomy alone.

Methods

In this prospective, non‐randomized comparative study, myomectomy was performed on 69 women with symptomatic myomas. Myomectomy alone was performed in 31 patients (Group I) and myomectomy with concomitant bilateral hypogastric arterial ligation was performed in 38 patients (Group II). In both groups, surgical results and clinical outcomes were evaluated by peripheral hemoglobin levels, a pictorial blood‐loss assessment chart, and visual analog scales. Spectral Doppler indices of uterine and ovarian stromal arteries, including peak systolic velocity, end‐diastolic velocity, pulsatility index and resistance index were performed preoperatively, and 1 day and 1 or more months postoperatively.

Results

Twenty‐two patients in Group I and 31 patients in Group II received regular follow‐up examinations for a mean follow‐up period of 10.1 months. Menstrual flow, dysmenorrhea and hemoglobin levels improved significantly after surgery in both groups. Blood loss during surgery was less in Group II than it was in Group I (P = 0.02). Doppler indices of uterine and ovarian stromal arteries from preoperation to mean follow‐up point were not significantly different between the groups, except for a significantly lower uterine artery pulsatility index in Group II (P = 0.01).

Conclusions

Myomectomy with hypogastric arterial ligation for symptomatic myomas is as efficient as is myomectomy alone and reduces blood loss during surgery. Serial Doppler studies showed that hypogastric ligation does not block uterine and ovarian perfusion, and even reduces the impedance of the uterine arteries. The long‐term recurrence rate after myomectomy with hypogastric arterial ligation remains to be determined. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Left ventricular diastolic function during normal pregnancy: assessment by spectral tissue Doppler imaging
Authors: Fok W. Y. , Chan L. Y. , Wong J. T. , Yu C. M. , Lau T. K.
Published: October 2006

Objective

Tissue Doppler imaging (TDI) is an echocardiographic technique for assessing the diastolic function that is relatively independent of preload. Since loading conditions change significantly during pregnancy, a load‐independent technique will give a more accurate assessment of diastolic function in pregnant women. The aim of this study was to evaluate maternal diastolic function using tissue Doppler imaging.

Methods

This was a prospective observational study on 35 healthy pregnant women. M‐mode, transmitral inflow (peak transmitral flow velocities during early diastole (E wave) and atrial contraction (A wave)) and TDI studies (peak myocardial velocities during early diastole (Em wave), during atrial contraction (Am wave) and peak systole in ejection phase (Sm)) were performed in each trimester and postpartum. The differences in variables between trimesters were analyzed.

Results

The peak transmitral inflow velocity during early diastole (E wave) was significantly decreased during the third trimester and postpartum. The peak flow velocity during atrial contraction (A wave) was increased in the second trimester, but decreased again in the third trimester and postpartum period. As a result, the E/A ratio progressively reduced as pregnancy advanced. TDI showed that peak myocardial velocities during early diastole (Em) tended to increase during the second trimester, and then decreased significantly in the third trimester or postpartum period. The peak myocardial velocities during atrial contraction (Am) increased significantly with advancing gestational age. As a consequence, both Em/Am and E/Em ratios decreased significantly throughout pregnancy.

Conclusions

This study demonstrates the changes in myocardial relaxation velocity throughout pregnancy. Because of its advantage of being relatively load‐independent, TDI may be a useful non‐invasive technique for monitoring maternal cardiac function in high‐risk pregnancies to detect the early signs of cardiac failure and to prevent further deterioration with prompt interventions. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Bilateral agenesis of the superior vena cava associated with congenital hydrothorax
Authors: Römer S. , Opgen‐Rhein B. , Chaoui R. , Scheer I. , Czernik C. , Obladen M.
Published: October 2006

Agenesis of the superior vena cava is a rare anomaly that is generally asymptomatic in the neonate. We report a male neonate with bilateral (total) agenesis of the superior vena cava with obstructed thoracic duct and subsequent congenital hydrothorax, anomalies that were detected by prenatal ultrasound at 25 weeks' gestation. The cardiac anomaly was confirmed by postnatal magnetic resonance angiography. The chylothorax disappeared with conservative therapy. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Ad hoc networks with heterogeneous smart antennas: performance analysis and protocols
Authors: Sundaresan Karthikeyan , Sivakumar Raghupathy
Published: October 2006

The use of smart antennas in wireless ad hoc networks has garnered attention over the last few years. Given the unique capabilities of smart antennas, and how they can improve performance in a typically constrained ad hoc network environment, the attention is with merit. However, not much light has been shed on wireless ad hoc networks that have nodes with varying antenna capabilities. While homogeneous ad hoc networks with all nodes having the same antenna capabilities will have certain applications, we argue that ad hoc networks with nodes having heterogeneous antenna capabilities are more likely to be the norm due to a variety of motivating factors. In this context, we answer two fundamental questions in this paper: (i)what is the theoretical capacity of an ad hoc network when its nodes have varying antenna capabilities? We consider nodes equipped with only omnidirectional antennas to those that are equipped with more sophisticated adaptive‐array and MIMO capable antennas. Perhaps more interestingly, we provide insights into what percentage of nodes in an ad hoc network have to be ‘smart’ to get a certain overall network capacity. (ii)What medium access control (MAC) and routing protocols should nodes use in such a heterogeneous network? We present MAC and routing protocols for ad hoc networks with heterogeneous antenna capabilities that allow nodes to interact with each othereffectivelydespite their heterogeneity, and in the process deliver considerably improved performance over simplistic strategies. We substantiate our theoretical results, and evaluate the proposed protocols using ns2‐based network simulations. Copyright © 2006 John Wiley & Sons, Ltd.
A new binary conflict resolution‐based MAC protocol for impulse‐based UWB ad hoc networks
Authors: Broustis Ioannis , Molle Mart , Krishnamurthy Srikanth , Faloutsos Michalis , Foerster Jeffrey
Published: October 2006

Ultra wide band (UWB) technology offers a promising high capacity solution for short‐range wireless ad hoc networks, as in home networks or in wearable ad hoc networks. In this paper, we propose a novel multi‐band MAC protocol for use in small ad hoc networks that deploy an underlying UWB based physical layer. In our approach, we divide the available UWB bandwidth into multiple simultaneously usable bands. In the absence of a sophisticated equalizer, the size of a slot for transmitting a UWB pulse is typically dictated by thedelay spreadof the channel. Therefore, using a wider frequency band to shorten the transmission time for each pulse does not increase the data rate in proportion to the available bandwidth. A multi‐band approach that uses a plurality of bands that adhere to FCC specifications, with slightly elongated pulse durations, provides a solution that can effectively utilize the UWB spectrum. Our approach is based on the idea of conflict resolution using binary ‘something’/‘nothing’ feedback, which has not been widely studied in wireless and specifically in UWB networks. Our protocol unites binary conflict resolution and multi‐band utilization to effectively utilize the available bandwidth. To ensure that our proposed approach is tightly knit with the underlying physical layer, we discuss physical–layer dependencies and the conformance to FCC‐imposed emission limits. We evaluate our approach via extensive simulations. Our simulation results demonstrate the significant advantages of our approach over single‐band solutions: the throughput increases significantly, and the number of collisions decreases considerably. Copyright © 2006 John Wiley & Sons, Ltd.
Mobility control for throughput maximization in ad hoc networks
Authors: Nadeem Tamer , Parthasarathy Srinivasan
Published: October 2006

Physical topology of an ad hoc wireless network imposes fundamental limits on its throughput capacity. In this work, we present a network design algorithm for configuring node locations in an 802.11 ad hoc network with the goal of improving the throughput capacity of the network. Given a network configuration (i.e., a mapping of network nodes to physical locations), we establish an inverse proportional relationship between the interference degree of the network and the guaranteed link‐throughput. Motivated by this observation, we present an algorithm which progressively guides the network towards better configurations with lower interference degrees, which in turn increases the network's throughput capacity. Packet level simulations using the ns‐2 simulator shows that the reconfigured topologies obtained by our algorithm consistently outperform the original network topologies for throughput and delay‐related metrics. In particular, for many cases, we observed over 100% increase in the total network throughput and the minimum guaranteed throughput, over 60% increase in throughput fairness and over 50% reduction in the mean‐service delay of packets. Our algorithm admits a simple distributed implementation and can be viewed as a distributed mobility control primitive for improving the throughput performance of mobile ad hoc networks. Alternately, our techniques can also be employed by a centralized designer during network creation time to obtain a network configuration with a high throughput capacity. To the best of our knowledge, ours is the first work which explores the use of guided network configuration strategies for improving the throughput capacity in ad hoc wireless networks. Copyright © 2006 John Wiley & Sons, Ltd.
Geo‐LANMAR: a scalable routing protocol for ad hoc networks with group motion
Authors: Zhou Biao , Lee Yeng‐Zhong , Gerla Mario , de Rango Floriano
Published: October 2006

Network scalability is one of the critical challenges and requirements in routing protocols for ad hoc networks. This paper presents a novel scalable routing protocol called Geo‐LANMAR. The proposed protocol inherits the group motion support of landmark routing (LANMAR) and applies the geo‐routing concept to deliver packets efficiently. In this framework, the integration between geo‐coordinates and table‐driven IP addressing is introduced. There is also an integration of group management with geo‐forwarding and IP group management. Geo‐LANMAR uses link‐state propagation over a virtual topology built on landmarks, and a fisheye like scheme makes this propagation very efficient. The virtual topology helps recover from voids. For extra efficiency, a novel metric called effective traveled distance (ETD) allows us to predict voids or obstacles.

With respect to LANMAR, Geo‐LANMAR reduces advertisement update overhead (O/H) and features robust forwarding. Consequently, Geo‐LANMAR is more scalable to large ad hoc networks with group motion. The performance evaluation of Geo‐LANMAR shows that Geo‐LANMAR gives high scalability for large networks in terms of control O/H, end‐to‐end delay, and packet delivery ratio as compared with other routing protocols such as AODV, LANMAR, and GPSR. Copyright © 2006 John Wiley & Sons, Ltd.
Dynamic combinatorial key management scheme for sensor networks
Authors: Moharrum Mohamed , Eltoweissy Mohamed , Mukkamala Ravi
Published: October 2006

Securing sensor networks has received much attention in the last few years. In a typical field deployment, a sensor network self‐organizes, closely interacts with its physical environment, and works unattended possibly in a hostile environment such as a battlefield. In such environments, sensor networks are subject to node capture as well as a myriad of other attacks. Constrained energy, memory, and computational capabilities of sensor nodes mandate a clever design of security solutions to minimize overhead while maintaining secure communications over the lifespan of the network. In this paper, we propose a Dynamic Combinatorial Key management scheme, DCK, to provide efficient, scalable, and survivable dynamic keying in a clustered sensor network with a large number of sensor nodes. DCK employs the Exclusion‐Basis Systems (EBS) as the underlying framework for key management at both the cluster and the sensor node levels. DCK enhances network security by localizing cluster key management functions, thus, limiting the impact of sensor node capture to the attacked cluster. Within a cluster, DCK decouples key generation, assignment, and distribution, and distributes the key management tasks among cluster nodes. Simulation results show that DCK is efficient in terms of energy consumption and storage. Also, it significantly outperforms other dynamic keying schemes, in particular with regards to energy consumed in key refreshment and re‐keying after node capture. Copyright © 2006 John Wiley & Sons, Ltd.
Molecular characterization of Portuguese patients with mucopolysaccharidosis type II shows evidence that the IDS gene is prone to splicing mutations
Authors: Alves S. , Mangas M. , Prata M. J. , Ribeiro G. , Lopes L. , Ribeiro H. , Pinto‐Basto J. , Lima M. Reis , Lacerda L.
Published: October 2006

Mucopolysaccharidosis type II (MPS II) is an X‐linked recessive lysosomal storage disease caused by a defect in the iduronate‐2‐sulfatase gene (IDS). Alternative splicing of the IDS gene can occur and the underlying regulatory mechanism may be rather complex. Nevertheless, little information is available on the role of variations at the IDS locus in the splicing process. Here we report that splice mutations at the IDS locus are an important source of MPS II pathogenicity, accounting for almost 56% of Portuguese cases. Among 16 unrelated Portuguese MPS II patients, 15 different mutations were identified: six intronic splice mutations (c.104−2AG, c.241−2A>G, c.241−1G>A, c.418+1G>A, c.880−8AG and c.1181−1G>C); two exonic splice mutations (c.1006G>lC and c.1122C>T); five missense mutations (D269V, D69V, D148N, R88C and P86L); one nonsense mutation (Q465Ter); one total IDS gene deletion; and one rearrangement involving a IDS gene inversion. Furthermore, nine of the 15 detected mutations affected the usual splicing pattern at the locus. Some of them are responsible for dramatic changes in the splicing mechanism. For example, the substitution mutation, c.418+1G>A, revealed the presence of an exonic sequence inside intron 3. Our study provides evidence that the IDS locus is prone to splicing mutations and that such susceptibility is particularly high in exon 3 and neighbouring regions. Consequently, mutation screening of the IDS gene cannot be restricted to gDNA examination. Unless cDNA analysis is also conducted, misclassifications as silent or missense mutations can be produced and even uncharacteristic splice‐site mutations can be misinterpreted as classic splicing defects that may generate severe, unconventional splicing alterations.
Land use change in Asia and the ecological consequences
Authors: Zhao Shuqing , Peng Changhui , Jiang Hong , Tian Dalun , Lei Xiangdong , Zhou Xiaolu
Published: October 2006

Viewed within a historical context, Asia has experienced dramatic land transformations, and currently more than 50% of Asian land area is under agriculture. The consequences of this transformation are manifold. Southeast Asia has the highest deforestation rate of any major tropical region. Many of the world's large rivers and lakes in Asia have been heavily degraded. About 11 of 19 world megacities with more than 10 million inhabitants are in Asia. These land use activities have resulted in substantial negative ecological consequences, including increased anthropogenic CO2emissions, deteriorated air and water quality, alteration of regional climate, an increase of disease and a loss of biodiversity. Although land use occurs at the local level, it has the potential to cause ecological impact across local, regional and global scales. Reducing the negative environmental impacts of land use change while maintaining economic viability and social acceptability is an major challenge for most developing countries in Asia.
Death‐associated protein 3 regulates cellular senescence through oxidative stress response
Authors: Murata Yoko , Wakoh Takeshi , Uekawa Natsuko , Sugimoto Masataka , Asai Azusa , Miyazaki Tadaaki , Maruyama Mitsuo
Published: October 2006

Death‐associated protein 3 (DAP3) has been originally identified as a positive mediator of apoptosis. It has been revealed recently that the predominant localization of DAP3 to mitochondria implies its functional involvement in mitochondrial metabolism in addition to apoptosis. However, little is known about the molecular basis of these physiological functions of DAP3. Here, we demonstrate that DAP3 is reduced in both replicative and premature senescence induced by oxidative stress, and the DAP3 reduction induced by oxidative stress is observed mostly in a mitochondrial fraction. Using DAP3‐specific short hairpin RNA (shRNA) in a clonogenic survival assay, we reveal that reduction of DAP3 induces resistance to oxidative stress and decreases intracellular reactive oxygen species (ROS) production. Furthermore, this strategy allows us to show that loss of DAP3 is involved in the avoidance of replicative senescence in mouse embryonic fibroblasts (MEFs). Thus, our study offers an insight into the potential regulatory function of mitochondrial DAP3 involved in cellular senescence.
Magnetic resonance imaging: is a single scan ever enough for the diagnosis of acoustic neuroma?
Authors: Kernohan M D , Blackmore K J , Johnson I J M , Zammit-Maempel I
Published: October 2006

A patient presented with unilateral, right-sided hearing loss and tinnitus and underwent gadolinium-enhanced magnetic resonance imaging (MRI). A pure tone audiogram showed a right-sided sensorineural hearing loss. The MRI scan was initially negative but when repeated seven years later, following a further deterioration of symptoms, it showed a 2 mm, right-sided acoustic neuroma.

This case has great potential significance for the diagnosis of acoustic neuroma, and it may raise medico-legal issues regarding the exclusion of this diagnosis. The case illustrates that a single negative scan may not be adequate if pure tone audiograms show deterioration in hearing loss.
Synovial chondromatosis of the temporomandibular joint, presenting as parotid mass
Authors: Hammodeh N , Nasser N A
Published: October 2006

Synovial chondromatosis is a condition which often affects the major joints. On rare occasions, it may affect the temporomandibular joint. We report such a case, which was mistakenly diagnosed and treated as a parotid mass. We include relevant radiological and histological investigations and a brief literature review.
Institutional Determinants of the Judicialisation of Policy in Brazil and Mexico
Authors: RIOS-FIGUEROA JULIO , TAYLOR MATTHEW M.
Published: October 2006

This article offers a comparative perspective on judicial involvement in policy change in Latin America during the last decade and a half. Drawing on the literature on new institutionalism and the judicialisation of politics, and on case studies from Latin America's two largest countries, we propose a comparative framework for analysing the judicialisation of policy in the region. On the basis of this framework, we argue that institutional structure is a primary determinant of patterns of the judicialisation of policy. In particular, institutional characteristics of the legal system affect the way political actors fight to achieve their policy objectives and the kinds of public justifications used to defend policy reform.
Contesting State Multiculturalisms: Indigenous Land Struggles in Eastern Panama
Authors: HORTON LYNN
Published: October 2006

This article examines the implications of Latin America's recent wave of state-embraced multiculturalism for the region's indigenous peoples, arguing that state recognition of indigenous difference is not inevitably empowering for indigenous groups or transformative of nation-states. It utilises data from fieldwork with the Kuna Indians of eastern Panama in order to delineate more precisely the contexts and strategies of indigenous peoples which may serve to push outwards more constrained forms of institutional multiculturalism. It explores the links between Panama's historical nationalist project, contemporary state multiculturalism and ethnically specific forms of mobilisation for land rights and autonomy. It also examines the transformative potential of multiculturalism in the context of the simultaneous implementation of global economic and cultural projects of neoliberalism.
Instabilities driven by ion shell distributions observed by Cluster in the midaltitude plasma sheet boundary layer
Authors: Ashour‐Abdalla M. , Leboeuf J. N. , Schriver D. , Bosqued J.‐M. , Cornilleau‐Wehrlin N. , Sotnikov V. , Marchaudon A. , Fazakerley A. N.
Published: October 2006

Cluster observations in the near‐Earth plasma sheet boundary layer (PSBL) region have shown the presence of ion shell distributions related to velocity‐dispersed ion structures (VDIS) coincident with electrostatic emissions. We have examined ion shell instabilities in the presence of a cold ion and electron background using linear theory and particle in cell simulations. Linear theory shows that the shell instability is only excited when a cold ion background is present, generating a broad range of ion cyclotron harmonics. Numerical simulations confirm that ion Bernstein modes are preferentially excited transverse to the ambient magnetic field, along with a lower level of wave power at oblique angles. The background ions are heated primarily in the transverse direction because of a linear nonstochastic ion cyclotron heating mechanism, and overall saturation of the instability occurs because of thermalization of the shell combined with heating of the background ions and electrons. Comparison with Cluster observations shows that observed electrostatic waves with a spectrum from a few Hz to several hundred Hz is in good agreement with that expected from the shell instability. The cold background ions are observed to have a temperature anisotropy with T⊥ > T∥, while electrons are observed to have T∥ > T⊥, also in qualitative agreement with the shell instability. The wave‐particle effects due to the shell instability in the near‐Earth PSBL could have important consequences for auroral potential structure at lower altitudes and may cause the gaps in VDIS structure leading to beamlets.
Chemical ozone loss in the Arctic and Antarctic stratosphere between 1992 and 2005
Authors: Tilmes Simone , Müller Rolf , Engel Andreas , Rex Markus , Russell James M.
Published: October 2006

The magnitude of chemical loss of polar ozone induced by anthropogenic halogens depends on the extent of chlorine activation, which is controlled by polar stratospheric clouds (PSCs) and thus by temperature. We propose a new quantity, the PSC formation potential (PFP) of the polar vortex, suitable for comparing the amount of ozone depletion in the Arctic and Antarctic regions. PFP represents the fraction of the vortex, over an ozone loss season, exposed to PSC temperatures. Chemical ozone loss in the Arctic correlates well with PFP, for winters between 1991 and 2005. For Antarctic and cold Arctic winters, PFP has been increasing over the past 30 years. In winter 2005, PFP and ozone loss in the Arctic reached record highs, approaching Antarctic levels. Nevertheless, column ozone in spring in the Arctic is much larger than the Antarctic, because of larger dynamical resupply of ozone to the Arctic.
Strong particle light absorption over the Pearl River Delta (south China) and Beijing (north China) determined from combined Raman lidar and Sun photometer observations
Authors: Müller D. , Tesche M. , Eichler H. , Engelmann R. , Althausen D. , Ansmann A. , Cheng Y. F. , Zhang Y. H. , Hu M.
Published: October 2006

Particle size and absorption properties have been determined from combined one‐wavelength Raman lidar and Sun photometer measurements in the Pearl River Delta (South China) in October 2004, and in Beijing (North China) in January 2005. Particle effective radius varied around 0.24 μm in the south of China. Aerosols were strongly light absorbing throughout the continental haze layers. The mean imaginary part was around 0.02i and the single‐scattering albedo was as low as 0.75 at 532 nm wavelength. Similar aerosol properties were found over Beijing.
A precisely dated climate record for the last 9 kyr from three high alpine stalagmites, Spannagel Cave, Austria
Authors: Vollweiler Nicole , Scholz Denis , Mühlinghaus Christian , Mangini Augusto , Spötl Christoph
Published: October 2006

Here we use the δ18O time‐series of three stalagmites from the high alpine Spannagel cave (Austria) which grew in small distance from each other to construct a precisely dated, continuous δ18O curve for the last 9 kyr (COMNISPA). This speleothem record is not influenced by effects of kinetic isotope fractionation due to the low temperatures in the cave. Thus, the variations in δ18O can be interpreted in terms of past climate change. COMNISPA exhibits several oscillations within the Holocene, and their timing and duration is in agreement with that documented by other alpine archives.
Reduction in seasonal sea ice concentration surrounding southern Baffin Island 1979–2004
Authors: Moore G. W. K.
Published: October 2006

Sea ice plays an important role in the climate and ecology of the Arctic. Numerous studies have identified a reduction in Arctic sea ice cover that has occurred over the past several decades, the period for which we have remotely sensed sea ice concentration data. The regional and seasonal expressions of this reduction have not been as extensively studied. In this paper, we describe the reduction in sea ice concentration that has occurred around southern Baffin Island, one of the Arctic's most biologically active regions. We show that a reduction in sea ice concentration, statistically significant at the 95% level or higher in the presence of temporally correlated noise, in the range of 10–20% per decade has occurred in the region with the largest reduction occurring during the early winter. This reduction is consistent with a recent statistically significant surface warming in the region during the fall and early winter.