bluuebunny/crossref_metadata_2025 huggingface dataset:
THE EFFECTS OF CO-DOPING OF B AND N ON THE ELECTRONIC TRANSPORT OF SINGLE-WALLED CARBON NANOTUBES
Authors: WEI JIANWEI , ZENG HUI , PU LICHUN , LIANG JUNWU , HU HUIFANG , PENG PING
Published: March 2011

Based on first-principle calculation, the geometry and electronic transport properties of the boron and nitrogen co-doping single-walled carbon nanotubes are investigated by using density functional theory combined with non-equilibrium Green's functions. The results show that the BN atoms energetically tend to form covalent bond of BN along axis in the nanotubes. In contrast to solely B or N doping, the co-doping do not generate accepter or donor subbands near the Fermi level. The co-doping give rise to the reduction of band gap in semiconducting (10, 0) tube and, furthermore, introduces the band gap to the metallic (5, 5) tube.
MOMENTUM SHIFT IN NONADIABATIC DYNAMICS
Authors: UKEN DANIEL A. , SERGI ALESSANDRO
Published: March 2011

We review the momentum-jump approximation in the quantum-classical Liouville formulation of nonadiabatic dynamics. We consider different momentum shift rules and study their numerical importance in computer simulations of the spin-boson model. Our findings might help the design of generalized sampling schemes of nonadiabatic dynamics at long time.
FRAME-SYNCHRONOUS AND LOCAL CONFIDENCE MEASURES FOR AUTOMATIC SPEECH RECOGNITION
Authors: RAZIK JOSEPH , MELLA ODILE , FOHR DOMINIQUE , HATON JEAN-PAUL
Published: March 2011

In this paper, we introduce two new confidence measures for large vocabulary speech recognition systems. The major feature of these measures is that they can be computed without waiting for the end of the audio stream. We proposed two kinds of confidence measures: frame-synchronous and local. The frame-synchronous ones can be computed as soon as a frame is processed by the recognition engine and are based on a likelihood ratio. The local measures estimate a local posterior probability in the vicinity of the word to analyze. We evaluated our confidence measures within the framework of the automatic transcription of French broadcast news with the EER criterion. Our local measures achieved results very close to the best state-of-the-art measure (EER of 23% compared to 22.0%). We then conducted a preliminary experiment to assess the contribution of our confidence measure in improving the comprehension of an automatic transcription for the hearing impaired. We introduced several modalities to highlight words of low confidence in this transcription. We showed that these modalities used with our local confidence measure improved the comprehension of automatic transcription.
FPCODE: AN EFFICIENT APPROACH FOR MULTI-MODAL BIOMETRICS
Authors: SHEN LINLIN , BAI LI , JI ZHEN
Published: March 2011

Although face recognition technology has progressed substantially, its performance is still not satisfactory due to the challenges of great variations in illumination, expression and occlusion. This paper aims to improve the accuracy of personal identification, when only few samples are registered as templates, by integrating multiple modal biometrics, i.e. face and palmprint. We developed in this paper a feature code, namely FPCode, to represent the features of both face and palmprint. Though feature code has been used for palmprint recognition in literature, it is first applied in this paper for face recognition and multi-modal biometrics. As the same feature is used, fusion is much easier. Experimental results show that both feature level and decision level fusion strategies achieve much better performance than single modal biometrics. The proposed approach uses fixed length 1/0 bits coding scheme that is very efficient in matching, and at the same time achieves higher accuracy than other fusion methods available in literature.
CORRIDOR DETECTION AND TRACKING FOR VISION-BASED DRIVER ASSISTANCE SYSTEM
Authors: JIANG RUYI , KLETTE REINHARD , VAUDREY TOBI , WANG SHIGANG
Published: March 2011

A significant component of driver assistance systems (DAS) is lane detection, and has been studied since the 1990s. However, improving and generalizing lane detection solutions proved to be a challenging task until recently. A (physical) lane is defined by road boundaries or various kinds of lane marks, and this is only partially applicable for modeling the space an ego-vehicle is able to drive in. This paper proposes a concept of (virtual) corridor for modeling this space. A corridor depends on information available about the motion of the ego-vehicle, as well as about the (physical) lane. This paper also suggests a modified version of Euclidean Distance Transform (EDT), named Row Orientation Distance Transform (RODT), to facilitate the detection of corridor boundary points. Then, boundary selection and road patch extension are applied as post-processing. Moreover, this paper also informs about the possible application of corridor for driver assistance. Finally, experiments using images from highways and urban roads with some challenging road situations are presented, illustrating the effectiveness of the proposed corridor detection algorithm. Comparison of lane and corridor on a public dataset is also provided.
INFRARED SMALL TARGET DETECTION ALGORITHM BASED ON FEATURE SALIENCE AND MULTI-FEATURES FUSION
Authors: CHEN ZHEN-XUE , LIU CHENG-YUN , CHANG FA-LIANG
Published: March 2011

It is an important and challenging problem to detect small targets in clutter scene and low SNR (Signal Noise Ratio) in infrared (IR) images. In order to solve this problem, a method based on feature salience is proposed for automatic detection of targets in complex background. Firstly, in this paper, the method utilizes the average absolute difference maximum (AADM) as the dissimilarity measurement between targets and background region to enhance targets. Secondly, minimum probability of error was used to build the model of feature salience. Finally, by computing the realistic degree of features, this method solves the problem of multi-feather fusion. Experimental results show that the algorithm proposed shows better performance with respect to the probability of detection. It is an effective and valuable small target detection algorithm under a complex background.
DANGEROUS KNOWLEDGE: CREDIT VALUE ADJUSTMENT WITH CREDIT TRIGGERS
Authors: YI CHUANG
Published: April 2011

We generalize the arbitrage-free valuation framework for counterparty credit risk (CCR) adjustments when credit triggers are allowed in the contract. The settlement of the deal for the investor could be either obliged or optional to execute when the counterparty hits the credit trigger before any default events from the two parties. General formulas for credit value adjustment (CVA) are given for all four cases: obliged unilateral, obliged bilateral, optional unilateral and optional bilateral. The unilateral CVA with an optional credit trigger is found to be the same as the unilateral CVA with an analogous obliged credit trigger. We show that adding credit triggers will decrease the unilateral CVA for both obliged and optional cases, which are in line with the motivation of investors to reduce CCR. However, adding credit triggers may not necessarily reduce bilateral CVA. Counter-intuitively, we show that the bilateral CVA may actually increase by adding credit triggers. Moreover, the increased amount of bilateral CVA due to credit triggers for one party is exactly the same amount of bilateral CVA reduced for the other party. The CVA calculation is subjected to large uncertainty of model risks, mostly due to the lack of data for calibrating jump-to-default probabilities. Some explicit models for obliged unilateral CVA are discussed with special caveats on the model assumptions. Numerical examples are also given to illustrate the model risk of CVA calculation due to the uncertainty of jump sizes, even though pure jump models are assumed.
PRICING OF PERPETUAL AMERICAN OPTIONS IN A MODEL WITH PARTIAL INFORMATION
Authors: GAPEEV PAVEL V.
Published: April 2011

We study the perpetual American call option pricing problem in a model of a financial market in which the firm issuing a traded asset can regulate the dividend rate by switching it between two constant values. The firm dividend policy is unknown for small investors, who can only observe the prices available from the market. The asset price dynamics are described by a geometric Brownian motion with a random drift rate modeled by a continuous time Markov chain with two states. The optimal exercise time of the option for small investors is found as the first time at which the asset price hits a boundary depending on the current state of the filtering dividend rate estimate. The proof is based on an embedding of the initial problem into a two-dimensional optimal stopping problem and the analysis of the associated parabolic-type free-boundary problem. We also provide closed form estimates for the rational option price and the optimal exercise boundary.
TARGET VOLATILITY OPTION PRICING
Authors: DI GRAZIANO GIUSEPPE , TORRICELLI LORENZO
Published: April 2011

In this paper we present two methods for the pricing of Target Volatility Options (TVOs), a recent market innovation in the field of volatility derivative. TVOs allow investors to take a joint view on the future price of a given underlying (e.g. stocks, commodities, etc) and its realized volatility. For example, a target volatility call pays at maturity the terminal value of the asset minus the strike, floored at zero, scaled by the ratio of the target volatility (an arbitrary constant) and the realized volatility of the underlying over the life of the option. TVOs are popular with investors and hedgers because they are typically cheaper than their vanilla equivalent. We present two approaches for the pricing of TVOs: a power series expansion and a Laplace transform method. We also provide both model dependent and model independent solutions. The pricing methodologies have been tested numerically and results are provided.
VALUATION AND HEDGING OF CDS COUNTERPARTY EXPOSURE IN A MARKOV COPULA MODEL
Authors: BIELECKI T. R. , CRÉPEY S. , JEANBLANC M. , ZARGARI B.
Published: April 2011

A Markov model is constructed for studying the counterparty risk in a CDS contract. The "wrong-way risk" in this model is accounted for by the possibility of the common default of the reference name and of the counterparty. A dynamic copula property as well as affine model specifications make pricing and calibration very efficient. We also consider the issue of dynamically hedging the CVA with a rolling CDS written on the counterparty. Numerical results are presented to show the adequacy of the behavior of CVA in the model with stylized features.
A PARSIMONIOUS MULTI-ASSET HESTON MODEL: CALIBRATION AND DERIVATIVE PRICING
Authors: DIMITROFF GEORGI , LORENZ STEFAN , SZIMAYER ALEXANDER
Published: April 2011

We propose a parsimonious multi-asset Heston model and provide an easy-to-implement calibration algorithm. The model is customized to pricing multi-asset options in markets with liquidly traded single-asset options but no liquidly traded cross-asset options. In this situation, single-asset model parameters can be calibrated from option price data, however, cross-asset parameters cannot. We formulate a parsimonious model specification such that all single-asset models are Heston models, which are affine allowing for efficient calibration of the respective parameters. The single-asset models are correlated using cross-asset correlations only. Cross-asset correlations are observable, in contrast to correlations of latent variables such as volatilities, and serve as basis for calibration. A hybrid calibration approach for identifying the model parameters consistent with option price data and asset price data is outlined and illustrated by a case study. In banking practice the approach is referred to as correlation adjustment.
MODELING LOSSY PROPAGATION OF NON-CLASSICAL LIGHT
Authors: YURTSEVER ULVI
Published: April 2011

The lossy propagation law (generalization of Lambert-Beer's law for classical radiation loss) for non-classical, dual-mode entangled states is derived from first principles, using an infinite-series of beam splitters to model continuous photon loss. This model is general enough to accommodate stray-photon noise along the propagation, as well as amplitude attenuation. An explicit analytical expression for the density matrix as a function of propagation distance is obtained for completely general input states with bounded photon number in each mode. The result is analyzed numerically for various examples of input states. For N00N state input, the loss of coherence and entanglement is super exponential, as predicted by a number of previous studies. However, for generic input states, where the coefficients are generated randomly, the decay of coherence is very different; in fact no worse than the classical Beer-Lambert law. More surprisingly, there is a plateau at a mid-range interval in propagation distance where the loss is in fact sub-classical, following which it resumes the classical rate. The qualitative behavior of the decay of entanglement for two-mode propagation is also analyzed numerically for ensembles of random states using the behavior of negativity as a function of propagation distance.
CONTINUOUS TIME QUANTUM WALKS AND QUOTIENT GRAPHS
Authors: SUFIANI R. , NAMI S. , GOLMOHAMMADI M. , JAFARIZADEH M. A.
Published: April 2011

Continuous-time quantum walks (CTQW) over finite group schemes is investigated, where it is shown that some properties of a CTQW over a group scheme defined on a finite group G induces a CTQW over group scheme defined on G/H, where H is a normal subgroup of G with prime index. This reduction can be helpful in analyzing CTQW on underlying graphs of group schemes. Even though this claim is proved for normal subgroups with prime index (using the Clifford's theorem from representation theory), it is checked in some examples that for other normal subgroups or even non-normal subgroups, the result is also true! It means that CTQW over the graph on G, starting from any arbitrary vertex, is isomorphic to the CTQW over the quotient graph on G/H if we take the sum of the amplitudes corresponding to the vertices belonging to the same cosets.
eLearning's Top Movers and Shakers
Authors: Little Bob
Published: April 2011

Its time for the second annual top movers and shakers. Columnist Bob Little shares his opinion on the 10 most influential practitioners, commentators, facilitators and/or thought leaders in the eLearning industry. Find out if you made the cut.
Properties and Evolution of Internet Traffic Networks from Anonymized Flow Data
Authors: Meiss Mark , Menczer Filippo , Vespignani Alessandro
Published: April 2011

Many projects have tried to analyze the structure and dynamics of application overlay networks on the Internet using packet analysis and network flow data. While such analysis is essential for a variety of network management and security tasks, it is infeasible on many networks: either the volume of data is so large as to make packet inspection intractable, or privacy concerns forbid packet capture and require the dissociation of network flows from users’ actual IP addresses. Our analytical framework permits useful analysis of network usage patterns even under circumstances where the only available source of data is anonymized flow records. Using this data, we are able to uncover distributions and scaling relations in host-to-host networks that bear implications for capacity planning and network application design. We also show how to classify network applications based entirely on topological properties of their overlay networks, yielding a taxonomy that allows us to accurately identify the functions of unknown applications. We repeat this analysis on a more recent dataset, allowing us to demonstrate that the aggregate behavior of users is remarkably stable even as the population changes.
Load Balancing and Range Queries in P2P Systems Using P-Ring
Authors: Crainiceanu Adina , Linga Prakash , Machanavajjhala Ashwin , Gehrke Johannes , Shanmugasundaram Jayavel
Published: April 2011

In peer-to-peer (P2P) systems, computers from around the globe share data and can participate in distributed computation. P2P became famous, and infamous, due to file-sharing systems like Napster. However, the scalability and robustness of these systems make them appealing to a wide range of applications.

This article introduces P-Ring, a new peer-to-peer index structure. P-Ring is fully distributed, fault tolerant, and provides load balancing and logarithmic search performance while supporting both equality and range queries. Our theoretical analysis as well as experimental results, obtained both in a simulated environment and on PlanetLab, show the performance of our system.
Composite ontology matching with uncertain mappings recovery
Authors: Fanizzi Nicola , d'Amato Claudia , Esposito Floriana
Published: April 2011

An automated ontology matching methodology is presented, supported by various machine learning techniques, as implemented in the system MoTo. The methodology is two-tiered. On the first stage it uses a meta-learner to elicit certain mappings from those predicted by single matchers induced by a specific base-learner. Then, uncertain mappings are recovered passing through a validation process, followed by the aggregation of the individual predictions through linguistic quantifiers. Experiments on benchmark ontologies demonstrate the effectiveness of the methodology.
Performance analysis of a hybrid MPI/CUDA implementation of the NASLU benchmark
Authors: Pennycook S. J. , Hammond S. D. , Jarvis S. A. , Mudalige G. R.
Published: April 2011

We present the performance analysis of a port of the LU benchmark from the NAS Parallel Benchmark (NPB) suite to NVIDIA's Compute Unified Device Architecture (CUDA), and report on the optimisation efforts employed to take advantage of this platform. Execution times are reported for several different GPUs, ranging from low-end consumergrade products to high-end HPC-grade devices, including the Tesla C2050 built on NVIDIA's Fermi processor.

We also utilise recently developed performance models of LU to facilitate a comparison between future large-scale distributed clusters of GPU devices and existing clusters built on traditional CPU architectures, including a quad-socket, quad-core AMD Opteron cluster and an IBM BlueGene/P.
A fast GEMM implementation on the cypress GPU
Authors: Nakasato Naohito
Published: April 2011

We present benchmark results of optimized dense matrix multiplication kernels for Cypress GPU. We write general matrix multiply (GEMM) kernels for single (SP), double (DP) and double-double (DDP) precision. Our SGEMM and DGEMM kernels show ~ 2 Top/s and ~ 470 Glop/s, respectively. These results for SP and DP correspond to 73% and 87% of the theoretical performance of the GPU, respectively. Currently, our SGEMM and DGEMM kernels are fastest with one GPU chip to our knowledge. Furthermore, the performance of our matrix multiply kernel in DDP is 31 Gop/s. This performance in DDP is more than 200 times faster than the performance results in DDP on single core of a recent CPU (with mpack version 0.6.5). We describe our GEMM kernels with main focus on the SGEMM implementation since all GEMM kernels share common programming and optimization techniques. While a conventional wisdom of GPU programming recommends us to heavily use shared memory on GPUs, we show that texture cache is very effective on the Cypress architecture.
Latent semantic indexing (LSI) fails for TREC collections
Authors: Atreya Avinash , Elkan Charles
Published: April 2011

The aim of latent semantic indexing (LSI) is to uncover the relationships between terms, hidden concepts, and documents. LSI uses the matrix factorization technique known as singular value decomposition (SVD). In this paper, we apply LSI to standard benchmark collections. We find that LSI yields poor retrieval accuracy on the TREC 2, 7, 8, and 2004 collections. We believe that the negative result is robust, because we try more LSI variants than any previous work. First, we show that using Okapi BM25 weights for terms in documents improves the performance of LSI. Second, we derive novel scoring methods that implement the ideas of query expansion and score regularization in the LSI framework. Third, we show how to combine the BM25 method with LSI methods. All proposed methods are evaluated experimentally on the four TREC collections mentioned above. The experiments show that the new variants of LSI improve upon previous LSI methods. Nevertheless, no way of using LSI achieves a worthwhile improvement in retrieval accuracy over BM25.
Inactive learning?
Authors: Attenberg Josh , Provost Foster
Published: April 2011

Despite the tremendous level of adoption of machine learning techniques in real-world settings, and the large volume of research on active learning, active learning techniques have been slow to gain substantial traction in practical applications. This reluctance of adoption is contrary to active learning's promise of reduced model-development costs and increased performance on a model-development budget. This essay presents several important and under-discussed challenges to using active learning well in practice. We hope this paper can serve as a call to arms for researchers in active learning--an encouragement to focus even more attention on how practitioners might actually use active learning.
Useful patterns (UP'10) ACM SIGKDD workshop report
Authors: Vreeken Jilles , Tatti Nikolaj , Goethals Bart
Published: April 2011

We provide a summary of the workshop on Useful Patterns (UP'10) held in conjunction with the ACM SIGKDD 2010, on July 25th in Washington, DC, USA. We report in detail on the motivation, goals, and the research issues addressed in the talks at this full-day workshop. More information can be found at: http://www.usefulpatterns.org.
Eighth workshop on mining and learning with graphs
Authors: Brefeld Ulf , Getoor Lise , Macskassy Sofus A.
Published: April 2011

The Eighth Workshop on Mining and Learning with Graphs (MLG)1was held at KDD 2010 in Washington DC. It brought together a variete of researchers interested in analyzing data that is best represented as a graph. Examples include the WWW, social networks, biological networks, communication networks, and many others. The importance of being able to effectively mine and learn from such data is growing, as more and more structured and semi-structured data is becoming available. This is a problem across widely different fields such as economics, statistics, social science, physics and computer science, and is studied within a variety of sub-disciplines of machine learning and data mining including graph mining, graphical models, kernel theory, statistical relational learning, etc. The objective of this workshop was to bring together practitioners from these various fields and areas to foster a rich discussion of which problems we work on, how we frame them in the context of graphs, which tools and algorithms we apply and our general findings and lessons learned. This year's workshop was very successful with well over 100 attendees, excellent keynote speakers and papers. This is a rapidly growing area and we believe that this community is only in its infancy. We hope that the readers will join us next year for MLG 2011.
A framework for mining interesting pattern sets
Authors: De Bie Tijl , Kontonasios Kleanthis-Nikolaos , Spyropoulou Eirini
Published: April 2011

This paper suggests a framework for mining subjectively interesting pattern sets that is based on two components: (1) the encoding of prior information in a model for the data miner's state of mind; (2) the search for a pattern set that is maximally informative while efficient to convey to the data miner.

We illustrate the framework with an instantiation for tile patterns in binary databases where prior information on the row and column marginals is available. This approach implements step (1) above by constructing the MaxEnt model with respect to the prior information [2, 3], and step (2) by relying on concepts from information and coding theory. We provide a brief overview of a number of possible extensions and future research challenges, including a key challenge related to the design of empirical evaluations for subjective interestingness measures.
From 'e' to 'we' Learnings
Authors: Little Bob
Published: April 2011

No one knows everything, but everyone knows something. Behind this truism lies the principle of empowerment through collaboration. It's hardly surprising that today's most innovative businesses are already using social networking principles to empower staff and benefit the wider organization through collaboration.
The Pros and Cons of Outsourcing e-Learning Services
Authors: Stayton Lee
Published: April 2011

Making the decision to use an outside vendor to meet your e-learning needs is never an easy task. But before you tie your project to a service provider, a careful analysis should be done. No two projects are alike, your needs will vary. Are you lacking expertise that an outside vendor could provide? Maybe you have the skills, but don't have the time to dedicate to the project. Whatever the case, having a clear sense of your e-learning needs will result in a more successful outsourcing experience.
Not Another Icebreaker!
Authors: Doctoroff Landay Susan
Published: April 2011

Lots of people hear the word "icebreaker" and cringe. Icebreakers are perceived as touchy-feely, frivolous, and a big waste of time. Still, despite their bad reputation, icebreakers remain a highly valued component of many learning sessions, no matter the age, level, or geographic location of the learners.
Promoting Information Processing and Ethical Use of Information for Online Learning
Authors: Mikuska Dorothy
Published: April 2011

The Internet has expanded the scope of learning; students can quickly access information from around the globe. Although computers can deliver flexibility and convenience, they can also disconnect students from academic responsibility. Emphasizing information processing and ethical behavior can lead to the transformation of electronic learning into excellent learning.
The Rising Popularity of Mobile Learning Southern Europe
Authors: Little Bob
Published: April 2011

For many years, the European markets for corporate e-learning have been strongest in the UK, followed by Germany and France. However corporate e-learning is slowly making its way across southern Europemainly Spain, Portugal, Italy and Greece.There are early signs of movement toward personalized, contextualized mobile learning rather than use what has become known as "traditional" computer delivered e-learning.
Mask Synthesis for Aerial Image Fidelity in Optical Lithography Using a Coarse-Grid-Approximation Level-Set Approach
Authors: Peng Yao , Zhang Jinyu , Wang Yan , Yu Zhiping
Published: March 2011

Inverse lithography technique, which treats mask synthesis as an inverse problem, has been considered as a strong contender to deal with the 45 nm technology node and beyond. But one problem exists in present pixel based mask synthesis algorithms: to describe mask patterns more accurately and to obtain better image quality, usually need finer grid representation, which results in extremely intensive computations. In this paper, a new method is proposed to mitigate this issue based on level-set method. This method utilizes the coarse-grid-approximation (CGA), which means the mask pattern defined on the fine grids is approximated using a new mask defined on coarse grids. The mask optimization is then performed on coarse girds and the final result is acquired by extracting mask patterns from coarse grids to fine grids. This method is demonstrated using a periodic array of contact holes pattern. Comparing with a gradient based algorithm and the traditional level-set algorithm, this method can provide almost the same image quality, but with over 100X running speed enhancement.
PYK2 signaling is required for PDGF-dependent vascular smooth muscle cell proliferation
Authors: Perez Jessica , Torres Rebecca A. , Rocic Petra , Cismowski Mary J. , Weber David S. , Darley-Usmar Victor M. , Lucchesi Pamela A.
Published: March 2011

Aberrant vascular smooth muscle cell (VSMC) growth is associated with many vascular diseases including atherosclerosis, hypertension, and restenosis. Platelet-derived growth factor-BB (PDGF) induces VSMC proliferation through control of cell cycle progression and protein and DNA synthesis. Multiple signaling cascades control VSMC growth, including members of the mitogen-activated protein kinase (MAPK) family as well as phosphatidylinositol 3-kinase (PI3K) and its downstream effector AKT/protein kinase B (PKB). Little is known about how these signals are integrated by mitogens and whether there are common receptor-proximal signaling control points that synchronize the execution of physiological growth functions. The nonreceptor proline-rich tyrosine kinase 2 (PYK2) is activated by a variety of growth factors and G protein receptor agonists in VSMC and lies upstream of both PI3K and MAPK cascades. The present study investigated the role of PYK2 in PDGF signaling in cultured rat aortic VSMC. PYK2 downregulation attenuated PDGF-dependent protein and DNA synthesis, which correlated with inhibition of AKT and extracellular signal-regulated kinases 1 and 2 (ERK1/2) but not p38 MAPK activation. Inhibition of PDGF-dependent protein kinase B (AKT) and ERK1/2 signaling by inhibitors of upstream kinases PI3K and MEK, respectively, as well as downregulation of PYK2 resulted in modulation of the G1/S phase of the cell cycle through inhibition of retinoblastoma protein (Rb) phosphorylation and cyclin D1 expression, as well as p27Kip upregulation. Cell division kinase 2 (cdc2) phosphorylation at G2/M was also contingent on PDGF-dependent PI3K-AKT and ERK1/2 signaling. These data suggest that PYK2 is an important upstream mediator in PDGF-dependent signaling cascades that regulate VSMC proliferation.
An acute bout of high-intensity interval training increases the nuclear abundance of PGC-1α and activates mitochondrial biogenesis in human skeletal muscle
Authors: Little Jonathan P. , Safdar Adeel , Bishop David , Tarnopolsky Mark A. , Gibala Martin J.
Published: March 2011

Low-volume, high-intensity interval training (HIT) increases skeletal muscle mitochondrial capacity, yet little is known regarding potential mechanisms promoting this adaptive response. Our purpose was to examine molecular processes involved in mitochondrial biogenesis in human skeletal muscle in response to an acute bout of HIT. Eight healthy men performed 4 × 30-s bursts of all-out maximal intensity cycling interspersed with 4 min of rest. Muscle biopsy samples (vastus lateralis) were obtained immediately before and after exercise, and after 3 and 24 h of recovery. At rest, the majority of peroxisome proliferator-activated receptor γ coactivator (PGC)-1α, a master regulator of mitochondrial biogenesis, was detected in cytosolic fractions. Exercise activated p38 MAPK and AMPK in the cytosol. Nuclear PGC-1α protein increased 3 h into recovery from exercise, a time point that coincided with increased mRNA expression of mitochondrial genes. This was followed by an increase in mitochondrial protein content and enzyme activity after 24 h of recovery. These findings support the hypothesis that an acute bout of low-volume HIT activates mitochondrial biogenesis through a mechanism involving increased nuclear abundance of PGC-1α.
MMP-9 gene deletion mitigates microvascular loss in a model of ischemic acute kidney injury
Authors: Lee So-Young , Hörbelt Markus , Mang Henry E. , Knipe Nicole L. , Bacallao Robert L. , Sado Yoshikazu , Sutton Timothy A.
Published: March 2011

Microvascular rarefaction following an episode of acute kidney injury (AKI) is associated with renal hypoxia and progression toward chronic kidney disease. The mechanisms contributing to microvascular rarefaction are not well-understood, although disruption in local angioregulatory substances is thought to contribute. Matrix metalloproteinase (MMP)-9 is an endopeptidase important in modifying the extracellular matrix (ECM) and remodeling the vasculature. We examined the role of MMP-9 gene deletion on microvascular rarefaction in a rodent model of ischemic AKI. MMP-9-null mice and background control (FVB/NJ) mice were subjected to bilateral renal artery clamping for 20 min followed by reperfusion for 14, 28, or 56 days. Serum creatinine level in MMP-9-null mice 24 h after injury [1.4 (SD 0.8) mg/dl] was not significantly different from FVB/NJ mice [1.5 (SD 0.6) mg/dl]. Four weeks after ischemic injury, FVB/NJ mice demonstrated a 30–40% loss of microvascular density compared with sham-operated (SO) mice. In contrast, microvascular density was not significantly different in the MMP-9-null mice at this time following injury compared with SO mice. FVB/NJ mice had a 50% decrease in tissue vascular endothelial growth factor (VEGF) 2 wk after ischemic insult compared with SO mice. A significant difference in VEGF was not observed in MMP-9-null mice compared with SO mice. There was no significant difference in the liberation of angioinhibitory fragments from the ECM between MMP-9-null mice and FVB/NJ mice following ischemic injury. In conclusion, MMP-9 deletion stabilizes microvascular density following ischemic AKI in part by preserving tissue VEGF levels.
Differential regulation of ROMK (Kir1.1) in distal nephron segments by dietary potassium
Authors: Wade James B. , Fang Liang , Coleman Richard A. , Liu Jie , Grimm P. Richard , Wang Tong , Welling Paul A.
Published: March 2011

ROMK channels are well-known to play a central role in renal K secretion, but the absence of highly specific and avid-ROMK antibodies has presented significant roadblocks toward mapping the extent of expression along the entire distal nephron and determining whether surface density of these channels is regulated in response to physiological stimuli. Here, we prepared new ROMK antibodies verified to be highly specific, using ROMK knockout mice as a control. Characterization with segmental markers revealed a more extensive pattern of ROMK expression along the entire distal nephron than previously thought, localizing to distal convoluted tubule regions, DCT1 and DCT2; the connecting tubule (CNT); and cortical collecting duct (CD). ROMK was diffusely distributed in intracellular compartments and at the apical membrane of each tubular region. Apical labeling was significantly increased by high-K diet in DCT2, CNT1, CNT2, and CD ( P < 0.05) but not in DCT1. Consistent with the large increase in apical ROMK, dramatically increased mature glycosylation was observed following dietary potassium augmentation. We conclude 1) our new antibody provides a unique tool to characterize ROMK channel localization and expression and 2) high-K diet causes a large increase in apical expression of ROMK in DCT2, CNT, and CD but not in DCT1, indicating that different regulatory mechanisms are involved in K diet-regulated ROMK channel functions in the distal nephron.
Adaptive Bacterial Foraging Optimization
Authors: Chen Hanning , Zhu Yunlong , Hu Kunyuan
Published: March 2011

Bacterial Foraging Optimization (BFO) is a recently developed nature‐inspired optimization algorithm, which is based on the foraging behavior of E. coli bacteria. Up to now, BFO has been applied successfully to some engineering problems due to its simplicity and ease of implementation. However, BFO possesses a poor convergence behavior over complex optimization problems as compared to other nature‐inspired optimization techniques. This paper first analyzes how the run‐length unit parameter of BFO controls the exploration of the whole search space and the exploitation of the promising areas. Then it presents a variation on the original BFO, called the adaptive bacterial foraging optimization (ABFO), employing the adaptive foraging strategies to improve the performance of the original BFO. This improvement is achieved by enabling the bacterial foraging algorithm to adjust the run‐length unit parameter dynamically during algorithm execution in order to balance the exploration/exploitation tradeoff. The experiments compare the performance of two versions of ABFO with the original BFO, the standard particle swarm optimization (PSO) and a real‐coded genetic algorithm (GA) on four widely‐used benchmark functions. The proposed ABFO shows a marked improvement in performance over the original BFO and appears to be comparable with the PSO and GA.
Interactions of Human Myeloid Cells with Natural Killer Cell Subsets In Vitro and In Vivo
Authors: Chijioke Obinna , Münz Christian
Published: March 2011

In both human and mouse it has been recently realized that natural killer (NK) cells do not emerge from the bone marrow with full functional competence but rather acquire functions in interaction with antigen‐presenting cells (APCs), primarily dendritic cells (DCs). Here we review the mechanisms and the consequences of this NK‐cell preactivation, as well as discuss new experimental models that now allow investigating these interactions for human NK cells and their response to human pathogens in vivo. These investigations will allow harnessing NK cells during vaccination for improved innate and adaptive immunity.
MicroRNA Gene Dosage Alterations and Drug Response in Lung Cancer
Authors: Enfield Katey S. S. , Stewart Greg L. , Pikor Larissa A. , Alvarez Carlos E. , Lam Stephen , Lam Wan L. , Chari Raj
Published: March 2011

Chemotherapy resistance is a key contributor to the dismal prognoses for lung cancer patients. While the majority of studies have focused on sequence mutations and expression changes in protein‐coding genes, recent reports have suggested that microRNA (miRNA) expression changes also play an influential role in chemotherapy response. However, the role of genetic alterations at miRNA loci in the context of chemotherapy response has yet to be investigated. In this study, we demonstrate the application of an integrative, multidimensional approach in order to identify miRNAs that are associated with chemotherapeutic resistance and sensitivity utilizing publicly available drug response, miRNA loci copy number, miRNA expression, and mRNA expression data from independent resources. By instigating a logical stepwise strategy, we have identified specific miRNAs that are associated with resistance to several chemotherapeutic agents and provide a proof of principle demonstration of how these various databases may be exploited to derive relevant pharmacogenomic results.
Clinical Evidence of the Efficacy of a Mouthwash ContainingPropolis for the Control of Plaque and Gingivitis: A Phase II Study
Authors: Pereira Elizete Maria Rita , da Silva João Luís Duval Cândido , Silva Fernando Freitas , De Luca Mariana Passos , Ferreira Efigênia Ferreira e , Lorentz Telma Campos Medeiros , Santos Vagner Rodrigues
Published: March 2011

The aim of this study was to evidence the clinical efficacy of an alcohol‐free mouthwash containing 5.0% (W/V) Brazilian green propolis (MGP 5%) for the control of plaque and gingivitis. Twenty five subjects, men and women aging between 18 and 60 years old (35 ± 9), were included in a clinical trials phase II study who had a minimum of 20 sound natural teeth, a mean plaque index of at least 1.5 (PI), and a mean gingival index of at least 1.0 (GI). They were instructed to rinse with 10 mL of mouthwash test for 1 minute, immediately after brushing in the morning and at night. After 45 and 90 days using mouthwash, the results showed a significant reduction in plaque and in gingival index when compared to samples obtained in baseline. These reductions were at 24% and 40%, respectively (P < .5). There were no important side effects in soft and hard tissues of the mouth. In this study, the MGP 5% showed evidence of its efficacy in reducing PI and GI. However, it is necessary to perform a clinical trial, double‐blind, randomized to validate such effectiveness.
Effects of Carbon Ion Beam on Putative Colon Cancer Stem Cells and Its Comparison with X-rays
Authors: Cui Xing , Oonishi Kazuhiko , Tsujii Hirohiko , Yasuda Takeshi , Matsumoto Yoshitaka , Furusawa Yoshiya , Akashi Makoto , Kamada Tadashi , Okayasu Ryuichi
Published: April 2011

Although carbon ion therapy facilities are expensive, the biological effects of carbon ion beam treatment may be better against cancer (and cancer stem cells) than the effects of a photon beam. To investigate whether a carbon ion beam may have a biological advantage over X-rays by targeting cancer stem–like cells, human colon cancer cells were used in vitro and in vivo. The in vitro relative biological effectiveness (RBE) values of a carbon ion beam relative to X-rays at the D10 values were from 1.63 to 1.74. Cancer stem–like CD133+, CD44+/ESA+ cells had a greater ability for colony and spheroid formation, as well as in vivo tumorigenicity compared with the CD133−, CD44−/ESA− cells. FACS (fluorescence-activated cell sorting) data showed that cancer stem–like cells were more highly enriched after irradiation with X-rays than carbon ion at doses that produced the same level of biological efficacy. A colony assay for cancer stem–like cells showed that RBE values calculated by the D10 levels were from 2.05 to 2.28 for the carbon ion beam relative to X-rays. The in vivo xenotransplant assay showed an RBE of 3.05 to 3.25, calculated from the slope of the dose–response curve for tumor growth suppression. Carbon ion irradiation with 15 Gy induced more severe xenograft tumor cell cavitation and fibrosis without significant enhancement of cells with putative cancer stem cell markers, CD133, ESA, and CD44, compared with 30 Gy X-rays, and marker positive cells were significantly decreased following 30 Gy carbon ion irradiation. Taken together, carbon ion beam therapy may have an advantage over photon beam therapy by improved targeting of putative colon cancer stem–like cells. Cancer Res; 71(10); 3676–87. ©2011 AACR.
Cancer-Associated Adipocytes Exhibit an Activated Phenotype and Contribute to Breast Cancer Invasion
Authors: Dirat Béatrice , Bochet Ludivine , Dabek Marta , Daviaud Danièle , Dauvillier Stéphanie , Majed Bilal , Wang Yuan Yuan , Meulle Aline , Salles Bernard , Le Gonidec Sophie , Garrido Ignacio , Escourrou Ghislaine , Valet Philippe , Muller Catherine
Published: April 2011

Early local tumor invasion in breast cancer results in a likely encounter between cancer cells and mature adipocytes, but the role of these fat cells in tumor progression remains unclear. We show that murine and human tumor cells cocultivated with mature adipocytes exhibit increased invasive capacities in vitro and in vivo, using an original two-dimensional coculture system. Likewise, adipocytes cultivated with cancer cells also exhibit an altered phenotype in terms of delipidation and decreased adipocyte markers associated with the occurrence of an activated state characterized by overexpression of proteases, including matrix metalloproteinase-11, and proinflammatory cytokines [interleukin (IL)-6, IL-1β]. In the case of IL-6, we show that it plays a key role in the acquired proinvasive effect by tumor cells. Equally important, we confirm the presence of these modified adipocytes in human breast tumors by immunohistochemistry and quantitative PCR. Interestingly, the tumors of larger size and/or with lymph nodes involvement exhibit the higher levels of IL-6 in tumor surrounding adipocytes. Collectively, all our data provide in vitro and in vivo evidence that (i) invasive cancer cells dramatically impact surrounding adipocytes; (ii) peritumoral adipocytes exhibit a modified phenotype and specific biological features sufficient to be named cancer-associated adipocytes (CAA); and (iii) CAAs modify the cancer cell characteristics/phenotype leading to a more aggressive behavior. Our results strongly support the innovative concept that adipocytes participate in a highly complex vicious cycle orchestrated by cancer cells to promote tumor progression that might be amplified in obese patients. Cancer Res; 71(7); 2455–65. ©2011 AACR.
Methylation of Retinoic Acid Receptor, Beta (RARB) Gene Increases Risk for Prostate Cancer in African-American Men
Authors: Rybicki B , Mitrache N , Do K , Jankowski M , Tang D , Rundle A , Bock C , Beebe-Dimmer J , Belinsky S
Published: March 2011

DNA methylation is an indicator of the initiation of prostate carcinogenesis and as such has utility as a marker of risk in pathologically negative prostate tissue samples. We conducted a matched case-control study nested in a historical cohort of over 6,000 men with pathologically benign prostate specimens identified between January 1991 and November 2002 with no previous history of prostate cancer. Eligible cases were diagnosed with prostate cancer at least one year after cohort entry. Controls were selected through incidence density sampling and matched to cases on date and age at cohort entry, race, and type of specimen. In 310 matched prostate cancer case-control pairs (65% white; 35% African American), we assayed the DNA of the benign prostate specimen for presence of methylation in a five-gene panel (APC, RARB, CCND2, RASSF1, MGMT) and then estimated the risk of developing prostate cancer associated with methylation at each gene for the whole sample and stratified by race. Overall, methylation of RARB had the strongest association with prostate cancer risk (HR = 1.94; 95% CI = 1.30 – 2.91). In race-stratified analyses, the majority of the increased risk associated with RARB was found in the African-American sample (HR = 3.40; 95% CI = 1.68–6.88). In addition, APC was also associated with increased risk for prostate cancer in the African-American sample (HR = 2.17; 95% CI = 1.09–4.29). In a model that included both genes, only RARB remained statistically significantly associated with prostate cancer (HR = 3.14; 95% CI = 1.54–6.44). In whites, methylation was not associated with prostate cancer for any of the five genes assayed. In summary, positive methylation status at RARB and APC in pathologically benign prostate is associated with significant increased risk for subsequent prostate cancer, but primarily in African-American men. Whether this race-specific risk is due to racial differences in environmental stimuli and/or biology is unclear, but further study of DNA methylation in the earliest stages of prostate carcinogenesis may help explain the disproportionate burden of this disease among African-American men.