bluuebunny/crossref_metadata_2025 huggingface dataset:
What's the difference?
Authors: Eppstein David , Goodrich Michael T. , Uyeda Frank , Varghese George
Published: December 2011

We describe a synopsis structure, the Difference Digest, that allows two nodes to compute the elements belonging to the set difference in a single round with communication overhead proportional to the
size of the difference
times the logarithm of the keyspace. While set reconciliation can be done efficiently using logs, logs require overhead for every update and scale poorly when multiple users are to be reconciled. By contrast, our abstraction assumes no prior context and is useful in networking and distributed systems applications such as trading blocks in a peer-to-peer network, and synchronizing link-state databases after a partition.

Our basic set-reconciliation method has a similarity with the peeling algorithm used in Tornado codes [6], which is not surprising, as there is an intimate connection between set difference and coding. Beyond set reconciliation, an essential component in our Difference Digest is a new estimator for the size of the set difference that outperforms min-wise sketches [3] for small set differences.

Our experiments show that the Difference Digest is more efficient than prior approaches such as Approximate Reconciliation Trees [5] and Characteristic Polynomial Interpolation [17]. We use Difference Digests to implement a generic KeyDiff service in Linux that runs over TCP and returns the sets of keys that differ between machines.
DevoFlow
Authors: Curtis Andrew R. , Mogul Jeffrey C. , Tourrilhes Jean , Yalagandula Praveen , Sharma Puneet , Banerjee Sujata
Published: December 2011

OpenFlow is a great concept, but its original design imposes excessive overheads. It can simplify network and traffic management in enterprise and data center environments, because it enables flow-level control over Ethernet switching and provides global visibility of the flows in the network. However, such fine-grained control and visibility comes with costs: the switch-implementation costs of involving the switch's control-plane too often and the distributed-system costs of involving the OpenFlow controller too frequently, both on flow setups and especially for statistics-gathering.

In this paper, we analyze these overheads, and show that OpenFlow's current design cannot meet the needs of high-performance networks. We design and evaluate DevoFlow, a modification of the OpenFlow model which gently breaks the coupling between control and global visibility, in a way that maintains a useful amount of visibility without imposing unnecessary costs. We evaluate DevoFlow through simulations, and find that it can load-balance data center traffic as well as fine-grained solutions, without as much overhead: DevoFlow uses 10--53 times fewer flow table entries at an average switch, and uses 10--42 times fewer control messages.
Debugging the data plane with anteater
Authors: Mai Haohui , Khurshid Ahmed , Agarwal Rachit , Caesar Matthew , Godfrey P. Brighten , King Samuel Talmadge
Published: December 2011

Diagnosing problems in networks is a time-consuming and error-prone process. Existing tools to assist operators primarily focus on analyzing control plane configuration. Configuration analysis is limited in that it cannot find bugs in router software, and is harder to generalize across protocols since it must model complex configuration languages and dynamic protocol behavior.

This paper studies an alternate approach: diagnosing problems through static analysis of the data plane. This approach can catch bugs that are invisible at the level of configuration files, and simplifies unified analysis of a network across many protocols and implementations. We present Anteater, a tool for checking invariants in the data plane. Anteater translates high-level network invariants into boolean satisfiability problems (SAT), checks them against network state using a SAT solver, and reports counterexamples if violations have been found. Applied to a large university network, Anteater revealed 23 bugs, including forwarding loops and stale ACL rules, with only five false positives. Nine of these faults are being fixed by campus network operators.
Seamless network-wide IGP migrations
Authors: Vanbever Laurent , Vissicchio Stefano , Pelsser Cristel , Francois Pierre , Bonaventure Olivier
Published: December 2011

Network-wide migrations of a running network, such as the replacement of a routing protocol or the modification of its configuration, can improve the performance, scalability, manageability, and security of the entire network. However, such migrations are an important source of concerns for network operators as the reconfiguration campaign can lead to long and service-affecting outages.

In this paper, we propose a methodology which addresses the problem of seamlessly modifying the configuration of commonly used link-state Interior Gateway Protocols (IGP). We illustrate the benefits of our methodology by considering several migration scenarios, including the addition or the removal of routing hierarchy in an existing IGP and the replacement of one IGP with another. We prove that a strict operational ordering can guarantee that the migration will not create IP transit service outages. Although finding a safe ordering is NP complete, we describe techniques which efficiently find such an ordering and evaluate them using both real-world and inferred ISP topologies. Finally, we describe the implementation of a provisioning system which automatically performs the migration by pushing the configurations on the routers in the appropriate order, while monitoring the entire migration process.
What can free money tell us on the virtual black market?
Authors: Woo Kyungmoon , Kwon Hyukmin , Kim Hyun-chul , Kim Chong-kwon , Kim Huy Kang
Published: December 2011

"Real money trading" or "Gold farming" refers to a set of illicit practices for gathering and distributing virtual goods in online games for real money. Unlike previous work, we use network-wide economic interactions among in-game characters as a lens to monitor, detect and identify gold farming networks. Our work is based on a set of real in-game trade activity logs collected for one month in year 2010 from the world's second largest MMORPG called AION (with 3.4 million subscribers). This is the first work that empirically (i) shows that "free money network" is a promising measure/approximation for detecting and characterizing gold farming networks, and (ii) measures the size of the free money net and in-game virtual economy in a large-scale MMORPG in terms of the cash flow.
LoKI
Authors: Baden Randy
Published: December 2011

Decentralized online social networks (OSNs) typically rely on the existence of a public key infrastructure (PKI), but certificate authorities (CAs) cannot scalably identify all of the members of an OSN. Our system, LoKI, uses the ubiquity of mobile devices to exchange secrets during real-world meetings that can be used for the purposes of identification in-band, allowing each user to easily discover the keys of many one-hop relationships in the OSN.

We measure the frequency of such real-world meetings among OSN users with data sets crawled from Facebook, Twitter, and Foursquare. We quantify the resources consumed on the mobile devices in terms of storage and battery based on traces that reveal the number of mobile devices expected to be seen under normal activity. Lastly, we describe a rendezvous service that enables background peer-to-peer (P2P) communication on non-rooted Android phones, which we believe to be a practical and necessary service for many mobile peer-to-peer systems.
Designing a testbed for large-scale distributed systems
Authors: Leng Christof , Lehn Max , Rehner Robert , Buchmann Alejandro
Published: December 2011

Different evaluation methods for distributed systems like prototyping, simulation and emulation have different tradeoffs. We present a testbed for Internet applications that supports real-network prototypes and multiple simulators with unchanged application code. To ensure maximum portability between runtimes, a compact but flexible system interface is defined.
Pomelo
Authors: Chen Zhuo , Chen Yang , Ding Cong , Deng Beixing , Li Xing
Published: December 2011

Computing the shortest-path distances between nodes is a key problem in analyzing social graphs. Traditional methods like breadth-first search (BFS) do not scale well with graph size. Recently, a Graph Coordinate System, called Orion, has been proposed to estimate shortest-path distances in a scalable way. Orion uses a landmark-based approach, which does not take account of the shortest-path distances between non-landmark nodes in coordinate calculation. Such biased input for the coordinate system cannot characterize the graph structure well. In this paper, we propose Pomelo, which calculates the graph coordinates in a decentralized manner. Every node in Pomelo computes its shortest-path distances to both nearby neighbors and some random distant neighbors. By introducing the novel partial BFS, the computational overhead of Pomelo is tunable. Our experimental results from different representative social graphs show that Pomelo greatly outperforms Orion in estimation accuracy while maintaining the same computational overhead.
Towards scalable and realistic node models for network simulators
Authors: Kristiansen Stein , Plagemann Thomas , Goebel Vera
Published: December 2011

Network simulators typically do not include node models. Our studies show that in networks such as mobile networks, the impact of nodes on performance can be significant. Existing techniques to simulate nodes' are not scalable for network simulations, and require a too large modelling effort to be feasible for network research. In this paper, we propose to capture flexible per-protocol performance profiles from real, running systems using instrumentation and traffic benchmarking techniques. By using the obtained profiles as input into an extended scheduler simulator, the behaviour of the node can be accurately reproduced. Since the processing overhead is represented statistically, we preserve scalability and a low modelling overhead.
CloudProphet
Authors: Li Ang , Zong Xuanran , Kandula Srikanth , Yang Xiaowei , Zhang Ming
Published: December 2011

Choosing the best-performing cloud for one's application is a critical problem for potential cloud customers. We propose CloudProphet, a trace-and-replay tool to predict a legacy application's performance if migrated to a cloud infrastructure. CloudProphet traces the workload of the application when running locally, and replays the same workload in the cloud for prediction. We discuss two key technical challenges in designing CloudProphet, and some preliminary results using a prototype implementation.
On the efficacy of fine-grained traffic splitting protocolsin data center networks
Authors: Dixit Advait , Prakash Pawan , Kompella Ramana Rao
Published: December 2011

Multi-rooted tree topologies are commonly used to construct high-bandwidth data center network fabrics. In these networks, switches typically rely on equal-cost multipath (ECMP) routing techniques to split traffic across multiple paths, such that packets within a flow traverse the same end-to-end path. Unfortunately, since ECMP splits traffic based on flow-granularity, it can cause load imbalance across paths resulting in poor utilization of network resources. More fine-grained traffic splitting techniques are typically not preferred because they can cause packet reordering that can, according to conventional wisdom, lead to severe TCP throughput degradation. In this work, we revisit this fact in the context of regular data center topologies such as fat-tree architectures. We argue that packet-level traffic splitting, where packets of a flow are sprayed through all available paths, would lead to a better load-balanced network, which in turn leads to significantly more balanced queues and much higher throughput compared to ECMP.
Eco-Sign
Authors: Chen Lien-Wu , Sharma Pranay , Tseng Yu-Chee
Published: December 2011

The Eco-Sign system is a traffic light control system for minimizing greenhouse gases emitted by idling vehicles at intersections. Eco-Sign provides the following features: (i) it can notify vehicles to turn on/off their engines based on expected waiting time for green lights at intersections, (ii) it can dynamically adjust traffic light timing to minimize the number of vehicles stopping at an intersection based on vehicle arrival and departure rates, and (iii) it is a fully distributed system in the sense that each intersection can learn its local traffic condition and optimize its traffic sign setting to prevent congestions and thus traffic jams. Eco-Sign thus demonstrates a new traffic light control system for environmental protection.
FSR
Authors: Ren Yiqing , Zhou Wenchao , Wang Anduo , Jia Limin , Gurney Alexander J.T. , Loo Boon Thau , Rexford Jennifer
Published: December 2011

We present the demonstration of a comprehensive toolkit for analyzing and implementing routing policies, ranging from high-level guidelines to specific router configurations. Our Formally Safe Routing (FSR) toolkit performs all of these functions from the same algebraic representation of routing policy. We show that routing algebra has a very natural translation to both integer constraints (to perform safety analysis using SMT solvers) and declarative programs (to generate distributed implementations). Our demonstration with realistic topologies and policies shows how FSR can detect problems in an AS's iBGP configuration, prove sufficient conditions for BGP safety, and empirically evaluate convergence time.
Towards energy-efficient streaming system for mobile hotspots
Authors: Chen Ming-Hung , Yang Chun-Yu , Chang Chun-Yun , Hsu Ming-Yuan , Lee Ke-Han , Chou Cheng-Fu
Published: December 2011

Modern mobile devices have become an important part of our daily life but the performance of multimedia applications still suffers from the constrained energy supply and communication bandwidth of the mobile devices. In this work, we develop an energy-efficient streaming system for mobile hotspots to achieve better Quality-of-Experience. Our main idea is (a) to avoid redundant 3G transmissions as well as reduce the usage of 3G links for those low residual-energy users, and (b) to enable nearby mobile users cooperatively to share the downloaded data via short-range interfaces. The experiment results shows our scheme can improve the system lifetime by 27%, and provide better throughput as well as lower loss rate than conversional 3G systems do.
Dasu - ISP characterization from the edge
Authors: Sánchez Mario A. , Otto John S. , Bischof Zachary S. , Bustamante Fabián E.
Published: December 2011

Evaluating and characterizing access ISPs is critical to consumers shopping for alternative services and governments surveying the availability of broadband services to their citizens. We present Dasu, a service for crowdsourcing ISP characterization to the edge of the network. Dasu is implemented as an extension to a popular BitTorrent client and has been available since July 2010. While the prototype uses BitTorrent as its host application, its design is agnostic to the particular host application. The demo showcases our current implementation using both a prerecorded execution trace and a live run.
WiFire
Authors: Wilhelm Matthias , Martinovic Ivan , Schmitt Jens B. , Lenders Vincent
Published: December 2011

Firewalls are extremely effective at enforcing security policies in wired networks. Perhaps surprisingly, firewalls are entirely nonexistent in the wireless domain. Yet, the need to selectively control and block radio communication is particularly high in a broadcast environment since any node may receive and send packets. In this demo, we present WiFire, a system that brings the firewall concept to wireless networks. First, WiFire detects and analyzes packets during their transmission, checking their content against a set of rules. It then relies on reactive jamming techniques to selectively block undesired communication. We show the feasibility and performance of WiFire, which is implemented on the USRP2 software-defined radio platform, in several scenarios with IEEE 802.15.4 radios. WiFire is able to classify and effectively block undesired communication without interfering with desired communication.
Visualizing anomalies in sensor networks
Authors: Liao Qi , Shi Lei , He Yuan , Li Rui , Su Zhong , Striegel Aaron , Liu Yunhao
Published: December 2011

Diagnosing a large-scale sensor network is a crucial but challenging task due to the spatiotemporally dynamic network behaviors of sensor nodes. In this demo, we present Sensor Anomaly Visualization Engine (SAVE), an integrated system that tackles the sensor network diagnosis problem using both visualization and anomaly detection analytics to guide the user quickly and accurately diagnose sensor network failures. Temporal expansion model, correlation graphs and dynamic projection views are proposed to effectively interpret the topological, correlational and dimensional sensor data dynamics and their anomalies. Through a real-world large-scale wireless sensor network deployment (GreenOrbs), we demonstrate that SAVE is able to help better locate the problem and further identify the root cause of major sensor network failures.
WiRE
Authors: Dhananjay Aditya , Tierney Matt , Li Jinyang , Subramanian Lakshminarayanan
Published: December 2011

Many rural areas in developing regions remain largely disconnected from the rest of the world due to low purchasing power and the exorbitant cost of existing connectivity solutions. Wireless Rural Extensions (WiRE) is a low-power rural wireless network architecture that provides inexpensive, self-sustainable, and high-bandwidth connectivity. WiRE relies on a high-bandwidth directional wireless backbone with local distribution networks to provide focused IP coverage. WiRE also provides cellular connectivity using OpenBTS-based GSM microcells. It supports a naming and addressing framework that inter-operates with traditional telecom networks and enables a wide range of mobile services on a common IP framework. The entire name network can be built by integrating a range of off-the-shelf components and existing open source tools.
Using NetMagic to observe fine-grained per-flow latency measurements
Authors: Li Tao , Sun Zhigang , Jia Chunbo , Su Qi , Lee Myungjin
Published: December 2011

We introduce NetMagic to demonstrate the efficacy of RLI architecture RLI for the fine-grained per-flow latency measurements. In this demo, the main function of RLI is implemented in NetMagic, which is the key component of our experimental network comprising several computers and switches. We are going to show how NetMagic can provide rapid implementation and evaluation of RLI architecture that is difficult with commercial switch or router platforms. In the demo, the estimated fine-grained per-flow latency by RLI is monitored and dynamically presented. Further, the true latency with a resolution of 8ns is also provided by NetMagic for the evaluation. The efficacy of RLI architecture can be observed in a real-time fashion by the difference between estimated latencies and true ones.
An online gaming testbed for peer-to-peer architectures
Authors: Lehn Max , Leng Christof , Rehner Robert , Triebel Tonio , Buchmann Alejandro
Published: December 2011

In this demo we present a testbed environment for Peer-to-Peer (P2P) game architectures. It is based on Planet PI4, an online multiplayer game whose gameplay provides a standard workload for a set of gaming-specific network interfaces. Its pluggable architecture allows for the evaluation and comparison of existing and new P2P networking approaches. Planet PI4 can run on a real network for prototypical evaluation as well as in a discrete-event simulator providing a reproducible environment.
Service hosting gateways
Authors: May Martin , Diot Christophe , Le Guyadec Pascal , Picconi Fabio , Roussel Joris , Soule Augustin
Published: December 2011

The success of broadband residential Internet access is changing the way home users consume digital content and services. Currently, each home service requires the installation of a separate physical box (for instance, the NetFlix box or IPTV set-top-boxes). Instead, we argue for deploying a single box in the home that is powerful and flexible enough to host a variety of home services. In addition, this box is managed by the Internet Service provider and is able to provide service guarantees. We call such a box a service-hosting gateway (
SHG
), as it combines the functionalities of the home gateway managed by the network service provider with the capability of hosting services. Isolation between such services is ensured by virtualization.

We demonstrate a prototype of our (
SHG
). It is based on the hardware platform that will be used for future home gateways. We illustrate the features of the
SHG
with multiple use cases ranging from simple service deployment scenarios to complex media distribution services and home automation features.
Optimizing a virtualized data center
Authors: Erickson David , Heller Brandon , Yang Shuang , Chu Jonathan , Ellithorpe Jonathan , Whyte Scott , Stuart Stephen , McKeown Nick , Parulkar Guru , Rosenblum Mendel
Published: December 2011

Many data centers extensively use virtual machines (VMs), which provide the flexibility to move workload among physical servers. VMs can be placed to maximize application performance, power efficiency, or even fault tolerance. However, VMs are typically repositioned without considering network topology, congestion, or traffic routes.

In this demo, we show a system, Virtue, which enables the comparison of different algorithms for VM placement and network routing at the scale of an entire data center. Our goal is to understand how placement and routing affect overall application performance by varying the types and mix of workloads, network topologies, and compute resources; these parameters will be available for demo attendees to explore.
Efficient content dissemination in heterogeneous networks prone to episodic connectivity
Authors: Krifa Amir , Mendonca Marc , Bin Rais Rao Naveed , Barakat Chadi , Turletti Thierry , Obraczka Katia
Published: December 2011

Ubiquity of portable computing devices coupled with wide availability of wireless communication present new impor- tant opportunities for applications involving media-rich content dissemination. However, as access networks become increasingly more heterogeneous, seamless data delivery across internets consisting of a variety of network technology becomes a real challenge. In this demonstration, we showcase a system that enables content dissemination over heterogeneous internets consisting of wired, infrastructure-based and infrastructure-less wireless networks that may be prone to intermittent connectivity. Using an efficient, yet flexible buffer management scheme, we are able to address application-specific performance requirements such as average delay, delivery probability, energy efficiency, etc. Our system uses the Message Delivery in Heterogeneous, Disruption-prone Networks (MeDeHa) [2]) framework to deliver messages across a heterogeneous internet coupled with History-Based Scheduling and Drop (HBSD) buffer management [1] as a way to optimize resources provided by opportunistic networks. MeDeHa, which is described in detail in [2], provides seamless data delivery over interconnecting networks of different types, i.e., infrastructure-based and infrastructure-less networks. MeDeHa's comprehensive approach to bridging infrastructure-based and infrastructureless networks also copes with intermittent connectivity. For this demonstration, we showcase a "complete stack" solution featuring, from to top to bottom, the DTN2 "bundle" layer, HBSD as an "external router" to DTN2, and MeDeHa, which handles message delivery. We have implemented, on a Linux-based testbed, (i) the MeDeHa framework, (ii) the HBSD [3] external router for the DTN2 [4] architecture.
Floyd--hoare logic for quantum programs
Authors: Ying Mingsheng
Published: December 2011

Floyd--Hoare logic is a foundation of axiomatic semantics of classical programs, and it provides effective proof techniques for reasoning about correctness of classical programs. To offer similar techniques for quantum program verification and to build a logical foundation of programming methodology for quantum computers, we develop a full-fledged Floyd--Hoare logic for both partial and total correctness of quantum programs. It is proved that this logic is (relatively) complete by exploiting the power of weakest preconditions and weakest liberal preconditions for quantum programs.
Law and disorder
Authors: Greengard Samuel
Published: December 2011

International law has always been a murky and Byzantine area. However, the Internet and digital technology have raised the stakes, the risks, and the challenges.
The difference engine
Authors: Armour Phillip G.
Published: December 2011

Observations on cognitive diversity and team performance.
Interfaces for the ordinary user
Authors: Olsen Kai A. , Malizia Alessio
Published: December 2011

Increasing the visibility and access to underlying file structure on consumer devices can vastly improve the user experience.
I/O virtualization
Authors: Waldspurger Carl , Rosenblum Mendel
Published: December 2011

Decoupling a logical device from its physical implementation offers many compelling advantages.
Creating languages in Racket
Authors: Flatt Matthew
Published: December 2011

Sometimes you just have to make a better mousetrap.
Bufferbloat
Authors: Gettys Jim , Nichols Kathleen
Published: December 2011

Networks without effective AQM may again be vulnerable to congestion collapse.
Where do people draw lines?
Authors: Cole Forrester , Golovinskiy Aleksey , Limpaecher Alex , Barros Heather Stoddart , Finkelstein Adam , Funkhouser Thomas , Rusinkiewicz Szymon
Published: December 2011

This paper presents the results of a study in which artists made line drawings intended to convey specific 3D shapes. The study was designed so that drawings could be registered with rendered images of 3D models, supporting an analysis of how well the locations of the artists' lines correlate with other artists', with current computer graphics (CG) line definitions, and with the underlying differential properties of the 3D surface. Lines drawn by artists in this study largely overlapped one another, particularly along the occluding contours of the object. Most lines that do not overlap contours overlap large gradients of the image intensity and correlate strongly with predictions made by recent line-drawing algorithms in CG. A few were not well described by any of the local properties considered in this study. The result of our work is a publicly available data set of aligned drawings, an analysis of where lines appear in that data set based on local properties of 3D models, and algorithms to predict where artists will draw lines for new scenes.
Apolipoprotein A-IV regulates chylomicron metabolism–mechanism and function
Authors: Kohan Alison B. , Wang Fei , Li Xiaoming , Bradshaw Suzanne , Yang Qing , Caldwell Jody L. , Bullock Tera M. , Tso Patrick
Published: December 2011

Dietary fat is an important mediator of atherosclerosis and obesity. Despite its importance in mediating metabolic disease, there is still much unknown about dietary fat absorption in the intestine and especially the detailed biological roles of intestinal apolipoproteins involved in that process. We were specifically interested in determining the physiological role of the intestinal apolipoprotein A-IV (A-IV) using A-IV knockout (KO) mice. A-IV is stimulated by fat absorption in the intestine and is secreted on nascent chylomicrons into intestinal lymph. We found that A-IV KO mice had reduced plasma triglyceride (TG) and cholesterol levels and that this hypolipidemia persisted on a high-fat diet. A-IV KO did not cause abnormal intestinal lipid absorption, food intake, or adiposity. Additionally, A-IV KO did not cause abnormal liver TG and cholesterol metabolism, as assessed by measuring hepatic lipid content, lipogenic and cholesterol synthetic gene expression, and in vivo VLDL secretion. Instead, A-IV KO resulted in the secretion of larger chylomicrons from the intestine into the lymph, and those chylomicrons were cleared from the plasma more slowly than wild-type chylomicrons. These data suggest that A-IV has a previously unknown role in mediating the metabolism of chylomicrons, and therefore may be important in regulating plasma lipid metabolism.
Lactobacillus reuteristrains reduce incidence and severity of experimental necrotizing enterocolitis via modulation of TLR4 and NF-κB signaling in the intestine
Authors: Liu Yuying , Fatheree Nicole Y. , Mangalat Nisha , Rhoads Jon Marc
Published: December 2011

Necrotizing enterocolitis (NEC) is the leading gastrointestinal cause of mortality and morbidity in the premature infant. Premature infants have a delay in intestinal colonization by commensal bacteria and colonization with potentially pathogenic organisms. Lactobacillus reuteri is a probiotic that inhibits enteric infections, modulates the immune system, and may be beneficial to prevent NEC. In previous studies, L. reuteri strains DSM 17938 and ATCC PTA 4659 differentially modulated inflammation in vitro; however, the strains had equivalent anti-inflammatory responses in LPS feeding-induced ileitis in neonatal rats in vivo. The impact of these two strains in the prevention of NEC has not been previously investigated. NEC was induced in newborn rats by orogastric formula feeding and exposure to hypoxia. L. reuteri was added to the formula to prevent NEC. NEC score, Toll-like receptor (TLR)-signaling genes, phospho-IκB activity, and cytokine levels in the intestine were examined. Both strains significantly increased survival rate and decreased the incidence and severity of NEC, with optimal effects from DSM 17938. In response to probiotic, mRNA expression of IL-6, TNF-α, TLR4, and NF-κB was significantly downregulated, while mRNA levels of anti-inflammatory cytokine IL-10 were significantly upregulated. In parallel, L. reuteri treatment led to decrease intestinal protein levels of TLR4 and cytokine levels of TNF-α and IL-1β in newborn rats with NEC. Both strains significantly inhibited not only intestinal LPS-induced phospho-IκB activity in an ex vivo study but also decreased the levels of phospho-IκB in the intestines of NEC rat model. Cow milk formula feeding produced a similar but milder proinflammatory profile in the intestine that was also ameliorated by 17938. Our studies demonstrate that each of the two L. reuteri strains has potential therapeutic value in our NEC model and in enteritis associated with cow milk feeding. These results support the concept that L. reuteri may represent a valuable treatment to prevent NEC.
Role of myosin Va in purinergic vesicular neurotransmission in the gut
Authors: Chaudhury Arun , He Xue-Dao , Goyal Raj K.
Published: December 2011

We examined the hypothesis that myosin Va, by transporting purinergic vesicles to the varicosity membrane for exocytosis, plays a key role in purinergic vesicular neurotransmission. Studies were performed in wild-type (WT) and myosin Va-deficient dilute, brown, nonagouti (DBA) mice. Intracellular microelectrode recordings were made in mouse antral muscle strips. Purinergic inhibitory junction potential (pIJP) was recorded under nonadrenergic noncholinergic conditions after masking the nitrergic junction potentials. DBA mice showed reduced pIJP but normal hyperpolarizing response to P2Y1 receptor agonist MRS-2365. To investigate the mechanism of reduced purinergic transmission in DBA mice, studies were performed in isolated varicosities obtained from homogenates of whole gut tissues by ultracentrifugation and sucrose cushion purification. Purinergic varicosities were identified in tissue sections and in isolated varicosities by immunostaining for the vesicular ATP transporter, the solute carrier protein SLC17A9. The varicosities were similar in WT and DBA mice. Myosin Va was markedly reduced in DBA varicosities compared with the WT varicosities. Proximity ligation assay showed that myosin Va was closely associated with SLC17A9. Vesicular exoendocytosis was examined by FM1–43 staining of varicosities, which showed that exoendocytosis after KCl stimulation was impaired in DBA varicosities compared with WT varicosities. These studies show that SLC17A9 identifies ATP-containing purinergic varicosities. Myosin Va associates with SLC17A9-stained vesicles and possibly transports them to varicosity membrane for exocytosis. In myosin Va-deficient mice, purinergic inhibitory neurotransmission is impaired.
Functional reentry and circus movement arrhythmias in the small intestine of normal and diabetic rats
Authors: Lammers Wim J. E. P. , Stephen B. , Karam S. M.
Published: December 2011

In a few recent studies, the presence of arrhythmias based on reentry and circus movement of the slow wave have been shown to occur in normal and diseased stomachs. To date, however, reentry has not been demonstrated before in any other part of the gastrointestinal system. No animals had to be killed for this study. Use was made of materials obtained during the course of another study in which 11 rats were treated with streptozotocin and housed with age-matched controls. After 3 and 7 mo, segments of duodenum, jejunum, and ileum were isolated and positioned in a tissue bath. Slow wave propagation was recorded with 121 extracellular electrodes. After the experiment, the propagation of the slow waves was reconstructed. In 10 of a total of 66 intestinal segments (15%), a circus movement of the slow wave was detected. These reentries were seen in control ( n = 2) as well as in 3-mo ( n = 2) and 7-mo ( n = 6) diabetic rats. Local conduction velocities and beat-to-beat intervals during the reentries were measured (0.42 ± 0.15 and 3.03 ± 0.67 cm/s, respectively) leading to a wavelength of 1.3 ± 0.5 cm and a circuit diameter of 4.1 ± 1.5 mm. This is the first demonstration of a reentrant arrhythmia in the small intestine of control and diabetic rats. Calculations of the size of the circuits indicate that they are small enough to fit inside the intestinal wall. Extrapolation based on measured velocities and rates indicate that reentrant arrhythmias are also possible in the distal small intestine of larger animals including humans.
Right ventricular regional wall curvedness and area strain in patients with repaired tetralogy of Fallot
Authors: Zhong Liang , Gobeawan Like , Su Yi , Tan Ju-Le , Ghista Dhanjoo , Chua Terrance , Tan Ru-San , Kassab Ghassan
Published: December 2011

A quantitative understanding of right ventricular (RV) remodeling in repaired tetralogy of Fallot (rTOF) is crucial for patient management. The objective of this study is to quantify the regional curvatures and area strain based on three-dimensional (3-D) reconstructions of the RV using cardiac magnetic resonance imaging (MRI). Fourteen ( 14 ) rTOF patients and nine ( 9 ) normal subjects underwent cardiac MRI scan. 3-D RV endocardial surface models were reconstructed from manually delineated contours and correspondence between end-diastole (ED) and end systole (ES) was determined. Regional curvedness ( C) and surface area at ED and ES were calculated as well as the area strain. The RV shape and deformation in rTOF patients differed from normal subjects in several respects. Firstly, the curvedness at ED (mean for 13 segments, 0.030 ± 0.0076 vs. 0.029 ± 0.0065 mm−1; P < 0.05) and ES (mean for 13 segments, 0.040 ± 0.012 vs. 0.034 ± 0.0072 mm−1; P < 0.001) was decreased by chronic pulmonary regurgitation. Secondly, the surface area increased significantly at ED (mean for 13 segments, 982 ± 192 vs. 1,397 ± 387 mm2; P < 0.001) and ES (mean for 13 segments, 576 ± 130 vs. 1,012 ± 302 mm2; P < 0.001). In particular, rTOF patients had significantly larger surface area than that in normal subjects in the free wall but not for the septal wall. Thirdly, area strain was significantly decreased (mean for 13 segments, 56 ± 6 vs. 34 ± 7%; P < 0.0001) in rTOF patients. Fourthly, there were increases in surface area at ED (5,726 ± 969 vs. 6,605 ± 1,122 mm2; P < 0.05) and ES (4,280 ± 758 vs. 5,569 ± 1,112 mm2; P < 0.01) and decrease in area strain (29 ± 8 vs. 18 ± 8%; P < 0.001) for RV outflow tract. These findings suggest significant geometric and strain differences between rTOF and normal subjects that may help guide therapeutic treatment.
Upregulation of osmo-mechanosensitive TRPV4 channel facilitates chronic hypoxia-induced myogenic tone and pulmonary hypertension
Authors: Yang Xiao-Ru , Lin Amanda H. Y. , Hughes Jennifer M. , Flavahan Nicholas A. , Cao Yuan-Ning , Liedtke Wolfgang , Sham James S. K.
Published: December 2011

Chronic hypoxia causes pulmonary hypertension with vascular remodeling, increase in vascular tone, and altered reactivity to agonists. These changes involve alterations in multiple Ca2+pathways in pulmonary arterial smooth muscle cells (PASMCs). We have previously shown that vanilloid (TRPV)- and melastatin-related transient receptor potential (TRPM) channels are expressed in pulmonary arteries (PAs). Here we found that TRPV4 was the only member of the TRPV and TRPM subfamilies upregulated in PAs of chronic hypoxic rats. The increase in TRPV4 expression occurred within 1 day of hypoxia exposure, indicative of an early hypoxic response. TRPV4 in PASMCs were found to be mechanosensitive. Osmo-mechanical stress imposed by hypotonic solution activated Ca2+transients; they were inhibited by TRPV4 specific short interfering RNA, the TRPV blocker ruthenium red, and the cytochrome P450 epoxygenase inhibitor N-(methylsulfonyl)-2-(2-propynyloxy)-benzenehexanamide. Consistent with TRPV4 upregulation, the Ca2+response induced by the TRPV4 agonist 4α-phorbol 12,13-didecanoate and hypotonicity was potentiated in hypoxic PASMCs. Moreover, a significant myogenic tone, sensitive to ruthenium red, was observed in pressurized endothelium denuded small PAs of hypoxic but not normoxic rats. The elevated basal intracellular Ca2+concentration in hypoxic PASMCs was also reduced by ruthenium red. In extension of these results, the development of pulmonary hypertension, right heart hypertrophy, and vascular remodeling was significantly delayed and suppressed in hypoxic trpv4−/−mice. These results suggest the novel concept that TRPV4 serves as a signal pathway crucial for the development of hypoxia-induced pulmonary hypertension. Its upregulation may provide a pathogenic feed-forward mechanism that promotes pulmonary hypertension via facilitated Ca2+influx, subsequently enhanced myogenic tone and vascular remodeling.
Role of vitamin C and E supplementation on IL-6 in response to training
Authors: Yfanti Christina , Fischer Christian P. , Nielsen Søren , Åkerström Thorbjörn , Nielsen Anders R. , Veskoukis Aristidis S. , Kouretas Demetrios , Lykkesfeldt Jens , Pilegaard Henriette , Pedersen Bente K.
Published: December 2011

Vitamin C and E supplementation has been shown to attenuate the acute exercise-induced increase in plasma interleukin-6 (IL-6) concentration. Here, we studied the effect of antioxidant vitamins on the regulation of IL-6 expression in muscle and the circulation in response to acute exercise before and after high-intensity endurance exercise training. Twenty-one young healthy men were allocated into either a vitamin (VT; vitamin C and E, n = 11) or a placebo (PL, n = 10) group. A 1-h acute bicycling exercise trial at 65% of maximal power output was performed before and after 12 wk of progressive endurance exercise training. In response to training, the acute exercise-induced IL-6 response was attenuated in PL ( P < 0.02), but not in VT ( P = 0.82). However, no clear difference between groups was observed (group × training: P = 0.13). Endurance exercise training also attenuated the acute exercise-induced increase in muscle-IL-6 mRNA in both groups. Oxidative stress, assessed by plasma protein carbonyls concentration, was overall higher in the VT compared with the PL group (group effect: P < 0.005). This was accompanied by a general increase in skeletal muscle mRNA expression of antioxidative enzymes, including catalase, copper-zinc superoxide dismutase, and glutathione peroxidase 1 mRNA expression in the VT group. However, skeletal muscle protein content of catalase, copper-zinc superoxide dismutase, or glutathione peroxidase 1 was not affected by training or supplementation. In conclusion, our results indicate that, although vitamin C and E supplementation may attenuate exercise-induced increases in plasma IL-6 there is no clear additive effect when combined with endurance training.
Electron density distribution and crystal structure of Ca1-x/2AlSi(N3-xOx):Eu2+(x∼ 0.11)
Authors: Urushihara Daisuke , Asaka Toru , Takeda Takashi , Hirosaki Naoto , Fukuda Koichiro
Published: December 2011

Crystal structure of Ca1-x/2AlSi(N3-xOx):Eu2+(x∼ 0.11) has been characterized using an X-ray powder diffractometer and a transmission electron microscope equipped with an energy dispersive X-ray analyzer (EDX) and an electron energy loss spectrometer (EELS). The title compound is orthorhombic with space groupCmc21,Z= 4, unit-cell dimensionsa= 0.979780(7) nm,b= 0.565197(4) nm,c= 0.506356(3) nm, andV= 0.280404(3) nm3. The atom ratio Al:Si was determined to be 1:1 by EDX, and the presence of O atoms in the crystal structure was confirmed by EELS. Thex-value and the atomic coordinates of the final structural model were determined by the Rietveld method. The maximum-entropy methods-based pattern fitting (MPF) method was used to confirm the validity of the structural model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The reliability indices calculated from MPF areRwp= 9.18%,S= 1.17,Rp= 6.77%,RB= 1.91%, andRF= 0.86%. Atomic arrangements of the final structural model are in an excellent agreement with the three dimensional electron-density distributions determined by MPF.
Synthesis and X-ray diffraction data of 7-methyl-cis-2-(1’-naphthyl)-2,3,4,5-tetrahydro-1H-benzo[b]azepin-4-ol
Authors: Macías M. A. , Henao J. A. , Sanabria Carlos Mario , Palma Alirio
Published: December 2011

The 7-methyl-cis-2-(1’-naphthyl)-2,3,4,5-tetrahydro-1H-benzo[b]azepin-4-ol (chemical formula C21H21NO) was prepared via the reductive cleavage of the bridged N-O bond of the corresponding 7-methyl-2-exo-(1′-naphthyl)-1,4-epoxytetrahydro-1-benzazepine. The X-ray powder diffraction pattern for the new compound was analyzed and found that the title compound crystallizes in a monoclinic system with space group P2/c (No. 13) and refined unit-cell parameters a = 11.012(2), b = 18.613(5), c = 7.316(4) Å, β = 102.88(3) ° and V = 1461.8(7) Å3.
The TOPAS symbolic computation system
Authors: Coelho A. A. , Evans J. , Evans I. , Kern A. , Parsons S.
Published: December 2011

Computer algebra removes much of the drudgery from mathematics; it allows users to formulate models by using the language of mathematics and to have those models evaluated with little effort. This symbolic form of representation is often thought of as being separate to dedicated computational programs such as Rietveld refinement. These dedicated programs are often written in low level languages; they are relatively inflexible in what they do and modifying them to change functionality in a small manner is often a major programming task. This paper describes a symbolic system that is integrated into the dedicated Rietveld refinement program called TOPAS. The symbolic component allows large functional changes to be made at run time and with a relatively small amount of effort. In addition, the system as a whole reduces the programming complexity at the developmental stage.
A Positive Feedback Signaling Loop between ATM and the Vitamin D Receptor Is Critical for Cancer Chemoprevention by Vitamin D
Authors: Ting Huei-Ju , Yasmin-Karim Sayeda , Yan Shian-Jang , Hsu Jong-Wei , Lin Tzu-Hua , Zeng Weisi , Messing James , Sheu Tzong-Jeng , Bao Bo-Ying , Li Willis X. , Messing Edward , Lee Yi-Fen
Published: December 2011

Both epidemiologic and laboratory studies have shown the chemopreventive effects of 1α,25-dihydroxyvitamin D3 (1,25-VD) in tumorigenesis. However, understanding of the molecular mechanism by which 1,25-VD prevents tumorigenesis remains incomplete. In this study, we used an established mouse model of chemical carcinogenesis to investigate how 1,25-VD prevents malignant transformation. In this model, 1,25-VD promoted expression of the DNA repair genes RAD50 and ATM, both of which are critical for mediating the signaling responses to DNA damage. Correspondingly, 1,25-VD protected cells from genotoxic stress and growth inhibition by promoting double-strand break DNA repair. Depletion of the vitamin D receptor (VDR) reduced these genoprotective effects and drove malignant transformation that could not be prevented by 1,25-VD, defining an essential role for VDR in mediating the anticancer effects of 1,25-VD. Notably, genotoxic stress activated ATM and VDR through phosphorylation of VDR. Mutations in VDR at putative ATM phosphorylation sites impaired the ability of ATM to enhance VDR transactivation activity, diminishing 1,25-VD–mediated induction of ATM and RAD50 expression. Together, our findings identify a novel vitamin D–mediated chemopreventive mechanism involving a positive feedback loop between the DNA repair proteins ATM and VDR. Cancer Res; 72(4); 958–68. ©2011 AACR.
Cochran-Armitage Test versus Logistic Regression in the Analysis of Genetic Association Studies
Authors: Wellek Stefan , Ziegler Andreas
Published: December 2011

Objective: The Cochran-Armitage trend test based on the linear regression model has become a standard procedure for association testing in case-control studies. In contrast, the logistic regression model is generally used for estimating effect sizes. The aim of this paper is to propose an approach that allows for association testing and parameter estimation by means of the same statistic. Methods/Results: The trend test is recommendable as a test of no association between genotype and risk of disease. It is a two-sample test for differences between cases and controls with respect to the average number of risk alleles occurring in the genotype of an individual. We argue that this difference is not of primary interest in genetic association studies. It should be replaced with the disease odds ratio, which can be assessed under both cohort sampling and case-control sampling. Conclusion: The Cochran-Armitage trend test should be replaced by the Wald statistic from a logistic regression model for hypothesis testing and estimation in genetic association studies.
Quantification of Systemic Delivery of Substrates for Intermediate Metabolism during Citrate Anticoagulation of Continuous Renal Replacement Therapy
Authors: Balik Martin , Zakharchenko Mykhaylo , Otahal Michal , Hruby Jan , Polak Ferdinand , Rusinova Katerina , Stach Zdenek , Vavrova Jaroslava , Jabor Antonin
Published: December 2011

Background: There are limited data on systemic delivery of metabolic substrates during citrate anticoagulation. The direct citrate measurements are usually not available. Methods: Patients on 2.2% acid-citrate-dextrose (ACD, n = 41) were compared to a control group on unfractionated heparin (n = 17). All were treated on 1.9-m2 polysulfone filters. Samples were taken from the central venous catheter, ports pre- and post-filter and from effluent. Results: The gain of citrate in CVVH (n = 18) was not different from CVVHDF (n = 23, p = 0.8). Mean gain of citrate was 25.4 ± 6.4 mmol/h. The systemic loads of lactate (p = 0.12) and glucose (p = 0.23) in CVVH were similar to CVVHDF. Mean inputs of lactate and glucose were 62.9 ± 21.1 and 26.6 ± 10.4 mmol/h, respectively. The mean difference between post- and prefilter unmeasured anions (d-UA) correlated with mean difference of citrate concentrations (p < 0.0001, r2 = 0.66). The estimated caloric load of the citrate modalities was 5,536 ± 1,385 kJ/ 24 h. Conclusions: ACD might represent a significant load of metabolic substrates, particularly if used with lactate buffer. Systemic delivery of citrate can be predicted using d-UA in the extracorporeal circuit.