bluuebunny/crossref_metadata_2025 huggingface dataset:
Reaction kinetics of 1,2-diaminobenzene with ethyl 2-oxopropanoate and 2,3-butanedione
Authors: Klicnar Jiří , Mindl Jaromír , Obořilová Ivana , Petříček Jaroslav , Štěrba Vojeslav
Published: June 2010

The reaction of 1,2-diaminobenzene with 2,3-butanedione is subject to general acid catalysis in acetate and phosphate buffers (pH 4-7). The rate-limiting step of formation of 2,3-dimethylquinoxaline consists in the protonation of dipolar tetrahedral intermediate. In the case of the reaction of 1,2-diaminobenzene with ethyl 2-oxopropanoate, the dehydration of carbinolamine gradually becomes rate-limiting with increasing pH in acetate buffers, whereas in phosphate buffers a new reaction pathway makes itself felt, viz. the formation of amide catalyzed by the basic buffer component and by hydroxide ion.
Revalidation for gastroenterologists, with or without sedation!
Authors: Loft Duncan E , Harris Adam W , Barrison Ian G
Published: June 2010

From 16 November 2009, all doctors require a license to practise in the UK. Revalidation encompasses relicensing and recertification. This article focuses on recertification for gastroenterologists. Revalidation should not be viewed as a threat, and for the vast majority of doctors it should be straightforward, with the aim of demonstrating safe doctors, while keeping to a minimum time spent on exhaustive data collection. Specialty specific standards for physician medicine are ready to be endorsed by the General Medical Council and the first revalidations will be introduced around 2011. Subspecialty specific standards for gastroenterology are under evaluation and in the early stages of consultation.
Phaeochromocytoma: diagnostic challenges for biochemical screening and diagnosis
Authors: Barron Jeffrey
Published: June 2010

The aim of this article is to provide knowledge of the origin of catecholamines and metabolites so that there can be an informed approach to the methods for biochemical screening for a possible phaeochromocytoma; The article includes a review of catecholamine and metadrenaline metabolism, with methods used in biochemical screening. In the adrenal medulla and a phaeochromocytoma, catecholamines continuously leak from chromaffin granules into the cytoplasm and are converted to metadrenalines. For a phaeochromocytoma to become biochemically detectable, metnoradrenaline secretion needs to rise fourfold, whereas noradrenaline secretion needs to rise 15-fold. The prevalence of a sporadic phaeochromocytoma is low; therefore false-positive results exceed true-positive results. Assay sensitivity is high because it is important not to miss a possible phaeochromocytoma. The use of urine or plasma fractionated metadrenalines as the first-line test has been recommended due to improved sensitivity. A negative result excludes a phaeochromocytoma. Only after a sporadic phaeochromocytoma has been diagnosed biochemically is it cost effective to request imaging. Sensitivities and specificities of the assays differ according to pre-test probabilities of the presence of a phaeochromocytoma, with hereditary and incidentalomas having a higher pre-test probability than sporadic phaeochromocytoma. In conclusion, in screening for a possible phaeochromocytoma, biochemical investigations should be completed first to exclude or establish the diagnosis. The preferred biochemical screening test is fractionated metadrenalines, including methoxytyramine so as not to miss dopamine-secreting tumours.
Feature
Authors: Muralitharan Morley , Agricola Sebastian , Manickavasagam Mukunth , Gray Chris
Published: June 2010

Open Innovation: Next Frontier In Global Biopharma Industry.
Scaling self-timed systems powered by mechanical vibration energy harvesting
Authors: Wenck Justin , Collier Jamie , Siebert Jeff , Amirtharajah Rajeevan
Published: June 2010

Passive energy harvesting from mechanical vibration has wide application in wearable devices and wireless sensors to complement or replace batteries. Energy harvesting efficiency can be increased by eliminating AC/DC conversion. A test chip demonstrating self-timing, power-on reset circuitry, and dynamic memory for energy harvesting AC voltages has been designed in 180 nm CMOS and tested. An energy scalable DSP architecture implements FIR filters that consume as little as 170 pJ per output sample. The on-chip DRAM retains data for up to 28 ms while register data is retained down to a supply voltage of 153 mV. Circuit operation is confirmed for supply frequencies between 60 Hz and 1 kHz with power consumption below 130 μW. Reaching the limits of miniaturization will require approaching the limits of power dissipation. We extrapolate from this DSP architecture to find the minimum volume required for mechanical vibration energy harvesting sensors.
Design considerations of sub-mW indoor light energy harvesting for wireless sensor systems
Authors: Wang W. S. , O'Donnell T. , Wang N. , Hayes M. , O'Flynn B. , O'Mathuna C.
Published: June 2010

For most wireless sensor networks, one common and major bottleneck is the limited battery lifetime. The frequent maintenance efforts associated with battery replacement significantly increase the system operational and logistics cost. Unnoticed power failures on nodes will degrade the system reliability and may lead to system failure. In building management applications, to solve this problem, small energy sources such as indoor light energy are promising to provide long-term power to these distributed wireless sensor nodes. This article provides comprehensive design considerations for an indoor light energy harvesting system for building management applications. Photovoltaic cells characteristics, energy storage units, power management circuit design, and power consumption pattern of the target mote are presented. Maximum power point tracking circuits are proposed which significantly increase the power obtained from the solar cells. The novel fast charge circuit reduces the charging time. A prototype was then successfully built and tested in various indoor light conditions to discover the practical issues of the design. The evaluation results show that the proposed prototype increases the power harvested from the PV cells by 30% and also accelerates the charging rate by 34% in a typical indoor lighting condition. By entirely eliminating the rechargeable battery as energy storage, the proposed system would expect an operational lifetime 10--20 years instead of the current less than 6 months battery lifetime.
ULS
Authors: Mohanty Saraju P. , Pradhan Dhiraj K.
Published: June 2010

Power dissipation is a major bottleneck for emerging applications, such as implantable systems, digital cameras, and multimedia processors. Each of these applications is essentially designed as an Analog/Mixed-Signal System-on-a-Chip (AMS-SoC). These AMS-SoCs are typically operated from a single power-supply source which is a battery providing a constant supply voltage. In order to reduce power dissipation of the AMS-SoCs, multiple-supply voltage and/or variable-supply voltage is used as an attractive low-power design approach. In the multiple-/variable-supply voltage AMS-SoCs the use of a DC-to-DC voltage-level shifter is critical. The voltage-level shifter is an overhead when its own power dissipation is high. In this article a new DC-to-DC voltage-level shifter is introduced that performs level-up shifting, level-down shifting, and blocking of voltages and is called Universal Level Shifter (ULS). The ULS is a unique component that reduces dynamic power and leakage of the AMS-SoCs while facilitating their reconfigurability. The system-level architectures for three AMS-SoCs, such as Drug Delivery Nano-Electro-Mechanical-System (DDNEMS), Secure Digital Camera (SDC), and Net-centric Multimedia Processor (NMP) are introduced to demonstrate the use the ULS for system-level power management. The article presents a design flow and an algorithm for optimal design of the ULS using a dual-Vthhigh-κ technique for efficient realization of ULS. A prototype ULS is presented for 32nm nano-CMOS technology node. The robustness of the ULS design is examined by performing three types of analysis, such as parametric, load, and power. It is observed that the ULS produces a stable output for voltages as low as 0.35 V and loads varying from 50fFto 120fF. The average power dissipation of the ULS with a 82fFcapacitive load is 5 μW.
Practical performance models for complex, popular applications
Authors: Thereska Eno , Doebel Bjoern , Zheng Alice X. , Nobel Peter
Published: June 2010

Perhaps surprisingly, no practical performance models exist for popular (and complex) client applications such as Adobe's Creative Suite, Microsoft's Office and Visual Studio, Mozilla, Halo 3, etc. There is currently no tool that automatically answers program developers', IT administrators' and end-users' simple what-if questions like "what happens to the performance of my favorite application X if I upgrade from Windows Vista to Windows 7?". This paper describes our approach towards constructing practical, versatile performance models to address this problem. The goal is to have these models be useful for application developers to help expand application testing coverage and for IT administrators to assist with understanding the performance consequences of a software, hardware or configuration change.

This paper's main contributions are in system building and performance modeling. We believe we have built applications that are easier to model because we have proactively instrumented them to export their state and associated metrics. This application-specific monitoring is always on and interesting data is collected from real, "in-the-wild" deployments. The models we are experimenting with are based on statistical techniques. They require no modifications to the OS or applications beyond the above instrumentation, and no explicit a priori model on how an OS or application should behave. We are in the process of learning from models we have constructed for several Microsoft products, including the Office suite, Visual Studio and Media Player. This paper presents preliminary findings from a large user deployment (several hundred thousand user sessions) of these applications that show the coverage and limitations of such models. These findings pushed us to move beyond averages/means and go into some depth into why client application performance has an inherently large variance.
A mean field model of work stealing in large-scale systems
Authors: Gast Nicolas , Bruno Gaujal
Published: June 2010

In this paper, we consider a generic model of computational grids, seen as several clusters of homogeneous processors. In such systems, a key issue when designing efficient job allocation policies is to balance the workload over the different resources.

We present a Markovian model for performance evaluation of such a policy, namely work stealing (idle processors steal work from others) in large-scale heterogeneous systems. Using mean field theory, we show that when the size of the system grows, it converges to a system of deterministic ordinary differential equations that allows one to compute the expectation of performance functions (such as average response times) as well as the distributions of these functions.
Elon
Authors: Dong Wei , Liu Yunhao , Wu Xiaofan , Gu Lin , Chen Chun
Published: June 2010

We present a new mechanism called Elon for enabling efficient and long-term reprogramming in wireless sensor networks. Elon reduces the transferred code size significantly by introducing the concept of replaceable component. It avoids the cost of hardware reboot with a novel software reboot mechanism. Moreover, it significantly prolongs the reprogramming lifetime by avoiding flash writes for TelosB nodes. Experimental results show that Elon transfers up to 120--389 times less information than Deluge, and 18-42 times less information than Stream. The software reboot mechanism that Elon applies reduces the rebooting cost by 50.4%-53.87% in terms of beacon packets, and 56.83% in terms of unsynchronized nodes. In addition, Elon prolongs the reprogramming lifetime by a factor of 2.3.
Distributed sensor network localization from local connectivity
Authors: Karbasi Amin , Oh Sewoong
Published: June 2010

This paper addresses the problem of determining the node locations in ad-hoc sensor networks when only connectivity information is available. In previous work, we showed that the localization algorithm MDS-MAP proposed by Y. Shang et al. is able to localize sensors up to a bounded error decreasing at a rate inversely proportional to the radio range r. The main limitation of MDS-MAP is the assumption that the available connectivity information is processed in a centralized way.

In this work we investigate a practically important question whether similar performance guarantees can be obtained in a distributed setting. In particular, we analyze the performance of the HOP-TERRAIN algorithm proposed by C. Savarese et al. This algorithm can be seen as a distributed version of the MDS-MAP algorithm. More precisely, assume that the radio range r=o(1) and that the network consists of n sensors positioned randomly on a d-dimensional unit cube and d+1 anchors in general positions. We show that when only connectivity information is available, for every unknown node i, the Euclidean distance between the estimate x
i
and the correct position x
i
is bounded by ||x
i
-x
i
|| < r
0
/r + o(1), where r
0
=C
d
(log n/ n)
(1/d)
for some constant C
d
which only depends on d. Furthermore, we illustrate that a similar bound holds for the range-based model, when the approximate measurement for the distances is provided.
Optimal recovery of single disk failure in RDP code storage systems
Authors: Xiang Liping , Xu Yinlong , Lui John C.S. , Chang Qian
Published: June 2010

Modern storage systems use thousands of inexpensive disks to meet the storage requirement of applications. To enhance the data availability, some form of redundancy is used. For example, conventional RAID-5 systems provide data availability for single disk failure only, while recent advanced coding techniques such as row-diagonal parity (RDP) can provide data availability with up to two disk failures. To reduce the probability of data unavailability, whenever a single disk fails, disk recovery (or rebuild) will be carried out. We show that conventional recovery scheme of RDP code for a single disk failure is inefficient and suboptimal. In this paper, we propose an optimal and efficient disk recovery scheme, Row-Diagonal Optimal Recovery (RDOR), for single disk failure of RDP code that has the following properties: (1) it is read optimal in the sense that it issues the smallest number of disk reads to recover the failed disk; (2) it has the load balancing property that all surviving disks will be subjected to the same amount of additional workload in rebuilding the failed disk. We carefully explore the design state space and theoretically show the optimality of RDOR. We carry out performance evaluation to quantify the merits of RDOR on some widely used disks.
Transparent, lightweight application execution replay on commodity multiprocessor operating systems
Authors: Laadan Oren , Viennot Nicolas , Nieh Jason
Published: June 2010

We present Scribe, the first system to provide transparent, low-overhead application record-replay and the ability to go live from replayed execution. Scribe introduces new lightweight operating system mechanisms, rendezvous and sync points, to efficiently record nondeterministic interactions such as related system calls, signals, and shared memory accesses. Rendezvous points make a partial ordering of execution based on system call dependencies sufficient for replay, avoiding the recording overhead of maintaining an exact execution ordering. Sync points convert asynchronous interactions that can occur at arbitrary times into synchronous events that are much easier to record and replay.

We have implemented Scribe without changing, relinking, or recompiling applications, libraries, or operating system kernels, and without any specialized hardware support such as hardware performance counters. It works on commodity Linux operating systems, and commodity multi-core and multiprocessor hardware. Our results show for the first time that an operating system mechanism can correctly and transparently record and replay multi-process and multi-threaded applications on commodity multiprocessors. Scribe recording overhead is less than 2.5% for server applications including Apache and MySQL, and less than 15% for desktop applications including Firefox, Acrobat, OpenOffice, parallel kernel compilation, and movie playback.
Leveraging parallelism for multi-dimensional packetclassification on software routers
Authors: Ma Yadi , Banerjee Suman , Lu Shan , Estan Cristian
Published: June 2010

We present a software-based solution to the multi-dimensional packet classification problem which can operate at high line speeds, e.g., in excess of 10 Gbps, using high-end multi-core desktop platforms available today. Our solution, called Storm, leverages a common notion that a subset of rules are likely to be popular over short durations of time. By identifying a suitable set of popular rules one can significantly speed up existing software-based classification algorithms. A key aspect of our design is in partitioning processor resources into various relevant tasks, such as continuously computing the popular rules based on a sampled subset of traffic, fast classification for traffic that matches popular rules, dealing with packets that do not match the most popular rules, and traffic sampling. Our results show that by using a single 8-core Xeon processor desktop platform, it is possible to sustain classification rates of more than 15 Gbps for representative rule sets of size in excess of 5-dimensional 9000 rules, with no packet losses. This performance is significantly superior to a 8-way implementation of a state-of-the-art packet classification software system running on the same 8-core machine. Therefore, we believe that our design of packet classification functions can be a useful classification building block for RouteBricks-style designs, where a core router might be constructed as a mesh of regular desktop machines.
CWS
Authors: Casale Giuliano , Mi Ningfang , Smirni Evgenia
Published: June 2010

We define CWS, a non-preemptive scheduling policy for workloads with correlated job sizes. CWS tackles the scheduling problem by inferring the expected sizes of upcoming jobs based on the structure of correlations and on the outcome of past scheduling decisions. Size prediction is achieved using a class of Hidden Markov Models (HMM) with continuous observation densities that describe job sizes. We show how the forward-backward algorithm of HMMs applies effectively in scheduling applications and how it can be used to derive closed-form expressions for size prediction. This is particularly simple to implement in the case of observation densities that are phase-type (PH-type) distributed, where existing fitting methods for Markovian point processes may also simplify the parameterization of the HMM workload model.

Based on the job size predictions, CWS emulates size-based policies which favor short jobs, with accuracy depending mainly on the HMM used to parametrize the scheduling algorithm. Extensive simulation and analysis illustrate that CWS is competitive with policies that assume exact information about the workload.
RSIO
Authors: Zheng Haoqiang , Nieh Jason
Published: June 2010

We present RSIO, a processor scheduling framework for improving the response time of latency-sensitive applications by monitoring accesses to I/O channels and inferring when user interactions occur. RSIO automatically identifies processes involved in a user interaction and boosts their priorities at the time the interaction occurs to improve system response time. RSIO also detects processes indirectly involved in processing an interaction, automatically accounting for dependencies and boosting their priorities accordingly. RSIO works with existing schedulers and requires no application modifications to identify periods of latency-sensitive application activity. We have implemented RSIO in Linux and measured its effectiveness on microbenchmarks and real applications. Our results show that RSIO is easy to use and can provide substantial improvements in system performance for latency-sensitive applications.
Load balancing via random local search in closed and open systems
Authors: Ganesh Ayalvadi , Lilienthal Sarah , Manjunath D. , Proutiere Alexandre , Simatos Florian
Published: June 2010

In this paper, we analyze the performance of random
load resampling and migration
strategies in parallel server systems. Clients initially attach to an arbitrary server, but may switch servers independently at random instants of time in an attempt to improve their service rate. This approach to load balancing contrasts with traditional approaches where clients make smart server selections upon arrival (e.g., Join-the-Shortest-Queue policy and variants thereof). Load resampling is particularly relevant in scenarios where clients cannot predict the load of a server before being actually attached to it. An important example is in wireless spectrum sharing where clients try to share a set of frequency bands in a distributed manner.

We first analyze the natural
Random Local Search (RLS)
strategy. Under this strategy, after sampling a new server randomly, clients only switch to it if their service rate is improved. In closed systems, where the client population is fixed, we derive tight estimates of the time it takes under RLS strategy to balance the load across servers. We then study open systems where clients arrive according to a random process and leave the system upon service completion. In this scenario, we analyze how client migrations within the system interact with the system dynamics induced by client arrivals and departures. We compare the load-aware RLS strategy to a load-oblivious strategy in which clients just randomly switch server without accounting for the server loads. Surprisingly, we show that both load-oblivious and load-aware strategies stabilize the system whenever this is at all possible. We further demonstrate, using large-system asymptotics, that the average client sojourn time under the load-oblivious strategy is not considerably reduced when clients apply smarter load-aware strategies.
An analytical framework to infer multihop path reliability in MANETs
Authors: Antunes Nelson , Jacinto Gonçalo , Pacheco António
Published: June 2010

Due to complexity and intractability reasons, most of the analytical studies on the reliability of communication paths in mobile ad hoc networks are based on the assumption of link independence. In this paper, an analytical framework is developed to characterize the random behavior of a multihop path and derive path metrics to characterize the reliability of paths. This is achieved through the modeling of a multihop path as a PDMP (piecewise deterministic Markov process). Two path based metrics are obtained as expectations of functionals of the process: the mean path duration and the path persistence. We show that these metrics are the unique solution of a set of integro-differential equations and provide a recursive scheme for their computation. Finally, numerical results illustrate the computation of the metrics; these results are compared with independent link approximation results.
Channel fragmentation in dynamic spectrum access systems
Authors: Coffman Ed , Robert Philippe , Simatos Florian , Tarumi Shuzo , Zussman Gil
Published: June 2010

Dynamic Spectrum Access systems exploit temporarily available spectrum ('white spaces') and can spread transmissions over a number of non-contiguous sub-channels. Such methods are highly beneficial in terms of spectrum utilization. However, excessive fragmentation degrades performance and hence off-sets the benefits. Thus, there is a need to study these processes so as to determine how to ensure acceptable levels of fragmentation. Hence, we present experimental and analytical results derived from a mathematical model. We model a system operating at capacity serving requests for bandwidth by assigning a collection of gaps (sub-channels) with no limitations on the fragment size. Our main theoretical result shows that even if fragments can be arbitrarily small, the system does not degrade with time. Namely, the average total number of fragments remains bounded. Within the very difficult class of dynamic fragmentation models (including models of storage fragmentation), this result appears to be the first of its kind. Extensive experimental results describe behavior, at times unexpected, of fragmentation under different algorithms. Our model also applies to dynamic linked-list storage allocation, and provides a novel analysis in that domain. We prove that, interestingly, the 50% rule of the classical (non-fragmented) allocation model carries over to our model. Overall, the paper provides insights into the potential behavior of practical fragmentation algorithms.
Successive c-optimal designs
Authors: Sagnol Guillaume , Bouhtou Mustapha , Gaubert Stéphane
Published: June 2010

We propose a new approach to optimize the deployment and the sampling rates of network monitoring tools, such as Netflow, on a large IP network. It reduces to solving a stochastic sequence of Second Order Cone Programs. We validate our approach with experiments relying on real data from a commercial network.
Deep diving into BitTorrent locality
Authors: Cuevas Rubén , Laoutaris Nikolaos , Yang Xiaoyuan , Siganos Georgos , Rodriguez Pablo
Published: June 2010

A substantial amount of work has recently gone into localizing BitTorrent traffic within an ISP in order to avoid excessive and often times unnecessary transit costs. In this work we aim to answer yet unanswered questions such as: what is the minimum and the maximum transit traffic reduction across hundreds of ISPs?, what are the win-win boundaries for ISPs and their users?, what is the maximum amount of transit traffic that can be localized without requiring fine-grained control of inter-AS overlay connections?, what is the impact to transit traffic from upgrades of residential broadband speeds?.
Optimal propagation of security patches in mobile wireless networks
Authors: Khouzani M.H. R. , Sarkar Saswati , Altman Eitan
Published: June 2010

Reliable security measures against outbreaks of malware is imperative to enable large scale proliferation of wireless technologies. Immunization and healing of the nodes through dissemination of security patches can counter the spread of a malware upon an epidemic outbreak. The distribution of patches however burdens the bandwidth which is scarce in wireless networks. The trade-offs between security risks and resource consumption can be attained by activating at any given time only fractions of dispatchers and dynamically selecting their packet transmission rates. We formulate the above trade-offs as an optimal control problem that seek to minimize the aggregate network costs that depend on security risks and resource consumed by the countermeasures. Using Pontryagin's maximum principle, we prove that the dynamic control strategies have simple structures. When the resource consumption cost is concave, optimal strategy is to use maximum resources for distribution of patches until a threshold time, upon which, the patching should halt. When the resource consumption cost is convex, the above transition is strict but continuous.
Managing the cost, energy consumption, and carbon footprint of internet services
Authors: Le Kien , Bilgir Ozlem , Bianchini Ricardo , Martonosi Margaret , Nguyen Thu D.
Published: June 2010

The large amount of energy consumed by Internet services represents significant and fast-growing financial and environmental costs. This paper introduces a general, optimization-based framework and several request distribution policies that enable multi-data-center services to manage their brown energy consumption and leverage green energy, while respecting their service-level agreements (SLAs) and minimizing energy cost. Our policies can be used to abide by caps on brown energy consumption that might arise from various scenarios such as government imposed Kyoto-style carbon limits. Extensive simulations and real experiments show that our policies allow a service to trade off consumption and cost. For example, using our policies, a service can reduce brown energy consumption by 24% for only a 10% increase in cost, while still abiding by SLAs.
Semidefinite optimization for transient analysis of queues
Authors: Osogami Takayuki , Raymond Rudy
Published: June 2010

We derive an upper bound on the tail distribution of the transient waiting time for the GI/GI/1 queue from a formulation of semidefinite programming (SDP). Our upper bounds are expressed in closed forms using the first two moments of the service time and the interarrival time. The upper bounds on the tail distributions are integrated to obtain the upper bounds on the corresponding expectations. We also extend the formulation of the SDP, using the higher moments of the service time and the interarrival time, and calculate upper bounds and lower bounds numerically.
CFTL
Authors: Park Dongchul , Debnath Biplob , Du David
Published: June 2010

The flash translation layer (FTL) is a software/hardware in terface inside NAND flash memory. Since FTL has a critical impact on the performance of NAND flash-based devices, a variety of FTL schemes have been proposed to improve their performance. In this paper, we propose a novel hybrid FTL scheme named Convertible Flash Translation Layer (CFTL). Unlike other existing FTLs using static address mapping schemes, CFTL is adaptive to data access patterns so that it can dynamically switch its mapping scheme to either a read-optimized or a write-optimized mapping scheme. In addition to this convertible scheme, we propose an efficient caching strategy to further improve the CFTL performance with only a simple hint. Consequently, both the convertible feature and the caching strategy empower CFTL to achieve good read performance as well as good write performance.
Distributed averaging in dynamic networks
Authors: Rajagopalan Shreevatsa , Shah Devavrat
Published: June 2010

Distributed averaging is a well-studied problem, and often a "prototype" for a class of fundamental questions arising in various disciplines. Previous work has considered the effect of dynamics in the network topology, in terms of changes in which communication links are present. Here, we analyze the other forms of dynamics, namely: changes in the values at the nodes, and nodes joining or leaving the network.
Delay optimal queue-based CSMA
Authors: Shah Devavrat , Shin Jinwoo
Published: June 2010

In the past year or so, an exciting progress has led to throughput optimal design of CSMA-based algorithms for wireless networks. However, such an algorithm suffers from very poor delay performance. A recent work suggests that it is impossible to design a CSMA-like simple algorithm that is throughput optimal and induces low delay for any wireless network. However, wireless networks arising in practice are formed by nodes placed, possibly arbitrarily, in some geographic area.

In this paper, we propose a CSMA algorithm with per-node average-delay bounded by a constant, independent of the network size, when the network has geometry (precisely, polynomial growth structure) that is present in
any
practical wireless network. Two novel features of our algorithm, crucial for its performance, are (a) choice of access probabilities as an appropriate function of queue-sizes, and (b) use of local network topological structures. Essentially, our algorithm is a queue-based CSMA with a minor difference that at each time instance a very small fraction of
frozen
nodes do not execute CSMA. Somewhat surprisingly, appropriate selection of such frozen nodes, in a distributed manner, lead to the delay optimal performance.
Characterizing and modeling user activity on smartphones
Authors: Shye Alex , Scholbrock Benjamin , Memik Gokhan , Dinda Peter A.
Published: June 2010

In this paper, we present a comprehensive analysis of real smartphone usage during a 6-month study of real user activity on the Android G1 smartphone. Our goal is to study the high-level characteristics of smartphone usage, and to understand the implications on optimizing smartphones, and their networks. Overall, we present 11 findings that cover general usage behavior, interaction with the battery, power consumption, network activity, frequently-run applications, and modeling usage states.
Characterizing the soft error vulnerability of multicores running multithreaded applications
Authors: Soundararajan Niranjan , Sivasubramaniam Anand , Narayanan Vijay
Published: June 2010

Multicores have become the platform of choice across all market segments. Cost-effective protection against soft errors is important in these environments, due to the need to move to lower technology generations and the exploding number of transistors on a chip. While multicores offer the flexibility of varying the number of application threads and the number of cores on which they run, the reliability impact of choosing one configuration over another is unclear. Our study reveals that the reliability costs vary dramatically between configurations and being unaware could lead to a sub-optimal choice.
Physiological Roles of the TRPM4 Channel Extracted from Background Currents
Authors: Guinamard Romain , Demion Marie , Launay Pierre
Published: June 2010

Calcium-activated nonselective cationic currents have been known for 30 years, but their physiological implications have remained unresolved until the recent cloning of the TRPM4 ion channel. Since then, TRPM4 has been identified as a key modulator of numerous calcium-dependent mechanisms such as the immune response, insulin secretion, cerebral artery constriction, respiratory rhythm, and cardiac conduction.
Bridging Innate and Adaptive Antitumor Immunity Targeting Glycans
Authors: Pashov Anastas , Monzavi-Karbassi Bejatolah , Raghava Gajendra P. S. , Kieber-Emmons Thomas
Published: June 2010

Effective immunotherapy for cancer depends on cellular responses to tumor antigens. The role of major histocompatibility complex (MHC) in T-cell recognition and T-cell receptor repertoire selection has become a central tenet in immunology. Structurally, this does not contradict earlier findings that T-cells can differentiate between small hapten structures like simple glycans. Understanding T-cell recognition of antigens as defined genetically by MHC and combinatorially by T cell receptors led to the “altered self” hypothesis. This notion reflects a more fundamental principle underlying immune surveillance and integrating evolutionarily and mechanistically diverse elements of the immune system. Danger associated molecular patterns, including those generated by glycan remodeling, represent an instance of altered self. A prominent example is the modification of the tumor-associated antigen MUC1. Similar examples emphasize glycan reactivity patterns of antigen receptors as a phenomenon bridging innate and adaptive but also humoral and cellular immunity and providing templates for immunotherapies.
Effects of a Severe Mountain Pine Beetle Epidemic in Western Alberta, Canada under Two Forest Management Scenarios
Authors: Schneider Richard R. , Latham Maria Cecilia , Stelfox Brad , Farr Dan , Boutin Stan
Published: June 2010

We used a simulation model to investigate possible effects of a severe mountain pine beetle (Dendroctonus ponderosaeHopkins) epidemic under two management scenarios in Alberta, Canada. Our simulated outbreak was based on the current epidemic in British Columbia, which may kill close to 80% of the province's pine volume. Our two management scenarios were conventional harvest and a pine-reduction strategy modeled on a component of Alberta's Mountain Pine Beetle Management Strategy. The pine strategy seeks to reduce the number of susceptible pine stands by 75% over the next 20 years through targeted harvesting by the forest industry. Our simulations showed that the pine strategy could not be effectively implemented, even if the onset of the beetle outbreak was delayed for 20 years. Even though we increased mill capacity by 20% and directed all harvesting to high volume pine stands during the pine strategy's surge cut, the amount of highly susceptible pine was reduced by only 43%. Additional pine volume remained within mixed stands that were not targeted by the pine strategy. When the outbreak occurred in each scenario, sufficient pine remained on the landscape for the beetle to cause the timber supply to collapse. Alternative management approaches and avenues for future research are discussed.
The Response ofEnterococcus faecalisV583 to Chloramphenicol Treatment
Authors: Aakra Ågot , Vebø Heidi , Indahl Ulf , Snipen Lars , Gjerstad Øystein , Lunde Merete , Nes Ingolf F.
Published: June 2010

ManyEnterococcus faecalisstrains display tolerance or resistance to many antibiotics, but genes that contribute to the resistance cannot be specified. The multiresistantE. faecalisV583, for which the complete genome sequence is available, survives and grows in media containing relatively high levels of chloramphenicol. No specific genes coding for chloramphenicol resistance has been recognized in V583. We used microarrays to identify genes and mechanisms behind the tolerance to chloramphenicol in V583, by comparison of cells treated with subinhibitory concentrations of chloramphenicol and untreated V583 cells. During a time course experiment, more than 600 genes were significantly differentially transcribed. Since chloramphenicol affects protein synthesis in bacteria, many genes involved in protein synthesis, for example, genes for ribosomal proteins, were induced. Genes involved in amino acid biosynthesis, for example, genes for tRNA synthetases and energy metabolism were downregulated, mainly. Among the upregulated genes were EF1732 and EF1733, which code for potential chloramphenicol transporters. Efflux of drug out of the cells may be one mechanism used by V583 to overcome the effect of chloramphenicol.
Fractals and Hidden Symmetries in DNA
Authors: Cattani Carlo
Published: June 2010

This paper deals with the digital complex representation of a
DNA sequence and the analysis of existing correlations by wavelets. The symbolic DNA sequence is mapped into a nonlinear time series. By studying this time series the existence of fractal shapes and symmetries will be shown. At first step, the indicator matrix enables us to recognize some typical patterns of nucleotide distribution. The DNA sequence, of the influenza virus A (H1N1), is investigated by using the
complex representation, together with the corresponding walks on DNA; in particular, it is shown that DNA walks are fractals. Finally, by using the wavelet analysis, the existence of symmetries is proven.
Numerical Investigation of Startup Instabilities in Parallel-Channel Natural Circulation Boiling Systems
Authors: Lakshmanan S. P. , Pandey Manmohan
Published: June 2010

The behaviour of a parallel-channel natural circulation boiling water reactor under a low-pressure low-power startup condition has been studied numerically (using RELAP5) and compared with its scaled model. The parallel-channel RELAP5 model is an extension of a single-channel model developed and validated with experimental results. Existence of in-phase and out-of-phase flashing instabilities in the parallel-channel systems is investigated through simulations under equal and unequal power boundary conditions in the channels. The effect of flow resistance on Type-I oscillations is explored. For nonidentical condition in the channels, the flow fluctuations in the parallel-channel systems are found to be out-of-phase.
One‐Step Route to Synthesize Multiwalled Carbon Nanotubes Filled with MgO Nanorods
Authors: Liu Jing , Guo Chunli , Ma Xiaojian , Sun Changhui , Li Fengxia , Qian Yitai
Published: June 2010

Multiwalled carbon nanotubes filled with MgO nanorods were synthesized through the reaction of ethanol and Mg powder in the presence of TiO2 at 400 °C. X‐ray powder diffraction indicated that the sample was composed of graphite and cubic MgO. Transmission electron microscopy studies showed that multi‐walled CNTs with the outer diameters of 70–130 nm were filled with discontinuous MgO nanorods whose diameter was in the range of 25–40 nm. The ratios of the band intensities (ID/IG = 0.67) in Raman spectrum implied that carbon nanotubes had good crystallinity. The influence of correlative reaction factors on the morphology of the sample and the possible formation mechanism were discussed.
Biological Role of Dystroglycan in Schwann Cell Function and Its Implications in Peripheral Nervous System Diseases
Authors: Masaki Toshihiro , Matsumura Kiichiro
Published: June 2010

Dystroglycan is a central component of the dystrophin-glycoprotein complex (DGC) that links extracellular matrix with cytoskeleton, expressed in a variety of fetal and adult tissues. Dystroglycan plays diverse roles in development and homeostasis including basement membrane formation, epithelial morphogenesis, membrane stability, cell polarization, and cell migration. In this paper, we will focus on biological role of dystroglycan in Schwann cell function, especially myelination. First, we review the molecular architecture of DGC in Schwann cell abaxonal membrane. Then, we will review the loss-of-function studies using targeted mutagenesis, which have revealed biological functions of each component of DGC in Schwann cells. Based on these findings, roles of dystroglycan in Schwann cell function, in myelination in particular, and its implications in diseases will be discussed in detail. Finally, in view of the fact that understanding the role of dystroglycan in Schwann cells is just beginning, future perspectives will be discussed.
Deregulated Intracellular Signaling by Mutated c-CBL in Myeloid Neoplasms
Authors: Ogawa Seishi , Shih Lee-Yung , Suzuki Takahiro , Otsu Makoto , Nakauchi Hiromitsu , Koeffler H. Phillip , Sanada Masashi
Published: June 2010

c-CBL encodes a 120-kDa protein involved in intracellular signal transduction in a wide variety of cell types. Recently, frequent mutations of c-CBL have been reported in myeloid neoplasms showing both myelodysplastic and myeloproliferative features, in which most mutations are present in a homozygous state, as a result of allelic conversion in 11q. c-CBL has ubiquitin E3 ligase activity for a wide variety of tyrosine kinases, and thereby, negatively regulates tyrosine kinase signaling. Accordingly, c-CBL seems to have tumor suppressor functions, loss of which promotes tumorigenesis. On the other hand, once mutated, it is converted to an oncogenic protein and commits to myeloid leukemogenesis through a kind of gain of function causing aberrant signal transduction. The inhibition of mutant CBL protein or signaling pathways that it activates would have a role in therapeutics of myeloid neoplasms with CBL mutations. Clin Cancer Res; 16(15); 3825–31. ©2010 AACR.
Outcomes of Endovascular Repair of Ruptured Descending Thoracic Aortic Aneurysms
Authors: Jonker Frederik H.W. , Verhagen Hence J.M. , Lin Peter H. , Heijmen Robin H. , Trimarchi Santi , Lee W. Anthony , Moll Frans L. , Athamneh Husam , Muhs Bart E.
Published: June 2010

Background—

Thoracic endovascular aortic repair offers a less invasive approach for the treatment of ruptured descending thoracic aortic aneurysms (rDTAA). Due to the low incidence of this life-threatening condition, little is known about the outcomes of endovascular repair of rDTAA and the factors that affect these outcomes.

Methods and Results—

We retrospectively investigated the outcomes of 87 patients who underwent thoracic endovascular aortic repair for rDTAA at 7 referral centers between 2002 and 2009. The mean age was 69.8±12 years and 69.0% of the patients were men. Hypovolemic shock was present in 21.8% of patients, and 40.2% were hemodynamically unstable. The 30-day mortality rate was 18.4%, and hypovolemic shock (odds ratio 4.75; 95% confidence interval, 1.37 to 16.5;
P
=0.014) and hemothorax at admission (odds ratio 6.65; 95% confidence interval, 1.64 to 27.1;
P
=0.008) were associated with increased 30-day mortality after adjusting for age. Stroke and paraplegia occurred each in 8.0%, and endoleak was diagnosed in 18.4% of patients within the first 30 days after thoracic endovascular aortic repair. Four additional patients died as a result of procedure-related complications during a median follow-up of 13 months; the estimated aneurysm-related mortality at 4 years was 25.4%.

Conclusion—

Endovascular repair of rDTAA is associated with encouraging results. The endovascular approach was associated with considerable rates of neurological complications and procedure-related complications such as endoleak.
Endothelin Activation of Reactive Oxygen Species Mediates Stress-Induced Pressor Response in Dahl Salt-Sensitive Prehypertensive Rats
Authors: D'Angelo Gerard , Loria Analia S. , Pollock David M. , Pollock Jennifer S.
Published: June 2010

Experiments were designed to test the hypothesis that endothelin (ET) and/or reactive oxygen species contribute to the pressor response induced by acute air jet stress in normotensive Dahl salt-sensitive rats maintained on a normal salt diet (prehypertensive). Mean arterial pressure was chronically monitored by telemetry before and after 3-day treatment with the free radical scavenger 4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl (Tempol) or ET receptor antagonists ABT-627 (ET A antagonist) or A-182086 (ET A/B antagonist) supplied in the drinking water. Rats were restrained and subjected to pulsatile air jet stress (3 minutes). Plasma samples at baseline and during acute stress were analyzed for 8-isoprostane (measure of reactive oxygen species production) and ET. Neither Tempol nor ET receptor antagonist treatment had an effect on baseline mean arterial pressure or plasma 8-isoprostane. The pressor response to acute stress was accompanied by significant increases in plasma 8-isoprostane and ET. Tempol significantly reduced both the total pressor response (area under the curve) and the stress-mediated increase in plasma 8-isoprostane; conversely, Tempol had no effect on the stress-induced increase in plasma ET. Combined ET
A/B
antagonism, but not selective ET
A
receptor blockade, similarly suppressed the pressor response to stress and stress-mediated rise in 8-isoprostane. Together these results indicate that reactive oxygen species contribute to the pressor response to acute air jet stress. Furthermore, the increase in reactive oxygen species occurs downstream of ET
B
receptor activation.
Sciatic Nerve of Diabetic Rat Treated With Epoetin Delta: Effects on C-Fibers and Blood Vessels Including Pericytes
Authors: Loesch Andrzej , Tang Helen , Cotter Mary A. , Cameron Norman E.
Published: June 2010

In diabetes mellitus (DM) reduced motor and sensory properties of peripheral nerves are linked with the dysfunction of neural vasculature. We investigated C-fibers and microvessels of sciatic nerve of normal, DM, and DM + epoetin delta-treated rats. C-fibers immunoreactive for calcitonin gene-related peptide (CGRP), tyrosine hydroxylase (TH), epoetin receptor (EpoR), and common β receptor subunit of the interleukin 3 receptor (IL-3Rβ) were present in all rats, whereas in DM and epoetin-treated rats C-fibers also showed neuronal (nNOS) and inducible (iNOS) nitric oxide synthases. The cross-sectional area of CGRPpositive C-fibers was decreased in DM, but it recovered after epoetin treatment. In all conditions, vascular endothelium showed scarce immunolabeling for endothelial nitric oxide synthase (eNOS); the profound immunoreactivity for eNOS, EpoR, and IL-3Rβ was in pericytes. Some perivascular autonomic nerves were damaged and IL-3Rβ positive. Findings are discussed in terms of declined sensory conduction velocity in DM, its improvement after epoetin treatment, and the possible vascular contribution to these phenomena.