bluuebunny/crossref_metadata_2025 huggingface dataset:
Controls on bud activation and tiller initiation in C3and C4tallgrass prairie grasses: the role of light and nitrogen
Authors: Williamson Melinda M. , Wilson Gail W.T. , Hartnett David C.
Published: December 2012

Population dynamics of perennial grasses in tallgrass prairie ecosystems are strongly influenced by vegetative outgrowth from their belowground bud banks. We examined the role of light and nitrogen in regulating tiller initiation and tested an integrated model of controls on bud dormancy and activation in several C3and C4grasses. In addition, we assessed the interaction of nitrogen and light quantity and red – far red spectral composition on tiller initiation. Belowground perennating organs of three C3and three C4species were grown under full light or dark conditions, amended with one of four nitrogen concentrations (0 to 350 ppm N). Dormant buds were also subjected to full light under different spectral compositions or to continuous darkness. Our results among C3grasses support the integrated model as light and nitrogen played important and interacting roles in the regulation of bud banks. However, differences in responses among C4grasses and a lack of light × nitrogen interactions suggest that an alternative model may be necessary for this functional group. Our results provide predictions of responses to nitrogen enrichment or light imitations in prairie ecosystems due to interacting disturbances such as reduction in fire frequencies, alterations in grazing intensities, or climate change.
Detection and localization of the endophyteUndifilum oxytropisin locoweed tissues
Authors: Reyna Roxanna , Cooke Peter , Grum Daniel , Cook Daniel , Creamer Rebecca
Published: December 2012

Poisoning of livestock owing to grazing on locoweeds results in significant economic losses in the western United States. Some Oxytropis spp. locoweeds contain a seed-transmitted endophytic fungus, Undifilum oxytropis, which produces the toxic alkaloid swainsonine. We sought to localize and characterize growth patterns of the fungus within leaves and petioles of Oxytropis lambertii Pursh and Oxytropis sericea Nutt. to help define the types of interactions between the fungus and its hosts. Vegetative hyphae were observed within locoweed tissues using integrated imaging. Topographical images from scanning electron microscopy revealed the presence of the endophyte in the pith tissue of petioles. The fungus was identified between plant cells but did not appear to penetrate host cells. Transmission electron microscopy images of thin sections revealed that hyphae were closely associated with host cell walls. Oxytropis sericea was innoculated with green fluorescent protein-transformed U. oxytropis and observed by confocal microscopy, confirming the presence of the endophyte hyphae in leaves and petioles. The fungus was identified only in the pith of petioles using fluorescence and in the vascular bundle throughout extracellular spaces in leaves. These results revealed no signs of a pathogenic interaction between plant and fungus and support the hypothesis of a mutualistic or commensal relationship.
American chestnut (Castanea dentata) to northern red oak (Quercus rubra): forest dynamics of an old-growth forest in the Blue Ridge Mountains, USA
Authors: van de Gevel Saskia L. , Hart Justin L. , Spond Mark D. , White Philip B. , Sutton Megan N. , Grissino-Mayer Henri D.
Published: December 2012

We analyzed tree species composition and age structure in a rare, old-growth Quercus rubra L. (northern red oak) forest at Bluff Mountain Preserve, North Carolina, to assess potential changes associated with Cryphonectria parasitica (Murrill) M.E. Barr (chestnut blight), selective logging, livestock grazing, ice storms, wind events, and fire history. We established forest inventory plots to determine the forest composition, vertical structure, and age of the high-elevation Q. rubra dominated forest. We developed the longest Q. rubra dendroecological history (1671–2009) in North America. Several living Q. rubra individuals were more than 250 years old. The frequency, magnitude, and spatial extent of canopy disturbance events were shown in radial growth trends in Q. rubra samples. We also examined Q. rubra climate – radial growth relationships to compare high-elevation Q. rubra climate response patterns with results from lower elevation Quercus dendroclimatological studies. Stand-wide release events corresponded with the loss of Castanea dentata (Marsh.) Borkh. (American chestnut) during the 1930s and frequent ice storms or wind events. Although we observed fire scars on living hardwood trees, we did not find fire scars on the remnant logs. The lack of fire scars on the remnant logs indicates that the observed fires likely occurred during the second half of the 20th century. Quercus rubra were most climatically sensitive to cool March temperatures. Quercus rubra sampled at higher elevations were more sensitive to temperature than lower elevation Quercus spp. trees, which may indicate higher sensitivity to March frosts. Quercus rubra has been a dominant species at Bluff Mountain for the past 300 years; however, our data indicate that the forest will transition to support a much stronger Acer saccharum Marsh. (sugar maple) component during the next 50 years. This study provides a multicentury perspective to guide conservation efforts and forest management in high-elevation Quercus spp. forests in the southern Appalachian Mountains.
Origin, elevation, and evolutionary success of hybrids and polyploids in British Columbia, Canada
Authors: Vamosi Jana C. , McEwen Jamie R.
Published: December 2012

Although it is well established that many clades have polyploidization in their evolutionary history, the question of whether polyploidization is actually adaptive is far from resolved. It has been hypothesized that the evolutionary advantages of polyploidy are context-dependent, although we have yet to clearly identify the geographical or ecological contexts in which polyploids are more common. One reason why polyploidy may be displaying idiosyncratic ecological patterns is that previous comparative studies have often not separated polyploids into allopolyploids and autopolyploids, and we posit that there may be important differences in the origin and evolutionary success between the two types. Here, we examine the distribution of allopolyploid, autopolyploid, and diploid hybrid species along an elevation gradient from sea level to ∼4500 m within British Columbia, Canada, and find that polyploids (especially those of hybrid origin) are disproportionately present at high elevations. These processes of hybridization and polyploidization may contribute to species richness patterns observed in British Columbia. We discuss whether the associations are more likely to be the result of differential ecological tolerance or differential origination rates of allopolyploids at higher elevations. These findings highlight the importance of studying both hybridization and polyploidy when considering the diversification process in plants.
A chronsequential approach to investigating microbial community shifts following clearcutting in Boreal Plain forest soils
Authors: Hynes Holly M. , Germida James J.
Published: December 2012

Impacts of forest harvesting are often assessed in short-term studies that ignore the longer term changes associated with the disturbance. A chronosequence approach was taken to investigate changes in microbial community size and composition over ∼20 years post-harvest in lodgepole pine ( Pinus contorta Douglas ex Loudon) stands of the Boreal Plain. The LFH and mineral Ae horizons of Orthic Gray Luvisolic soils were sampled in six cutblocks, aged 1–19 years since harvest, in 2009 and 2010. Changes in microbial communities were assessed using phospholipid fatty acid analysis (PLFA) and 16S rDNA analysis. Physical and chemical soil parameters were measured to delineate microsite changes impacting microbial community shifts. Total microbial biomass (PLFA) was unaffected by harvesting disturbance, although fungal biomass was significantly larger in the oldest cutblock of the chronosequence. Microbial community composition did, however, differ between younger and older cutblocks as indicated by both lipid PLFA and 16S rDNA fingerprinting techniques. Forest soil microbial communities subject to clearcutting were observed to shift in overall community composition while remaining consistent in overall community size. The shift in community composition, which occurred in concert with the maintenance of biomass, indicated that the microbial community adapted sufficiently to the new post-harvest microsite conditions.
Recent advances in the synthesis of colloidal nanowires
Authors: Repko Anton , Cademartiri Ludovico
Published: December 2012

We review critically the advances in the synthesis of colloidal nanowires that have occurred over the past three years, with a focus on those that produced very thin (or “ultrathin”) nanowires (∼2–3 nm in diameter or less). We discuss the importance of these ultrathin nanowires, especially in light of the emerging evidence of their topological properties and their potential similarities with polymers.
Secrets revealed — Spatially selective wetting of plasma-patterned periodic mesoporous organosilica
Authors: Wang Wendong , Burgess Ian B. , Hatton Benjamin D. , Alvarenga Jack , Aizenberg Joanna
Published: December 2012

We report a simple method to pattern wetting properties on thin films of periodic mesoporous organosilica (PMO). A hydrophobic methane PMO thin film was covered by masks and exposed to oxygen plasma to make the unmasked area hydrophilic. The wettability patterns could be revealed only when the films were immersed in water or exposed to moisture. We expect that our method would extend the utility of PMO to such areas as sensing and information security.
Changing perspectives on regeneration ecology and genetic diversity in western quaking aspen: implications for silviculture
Authors: Long James N. , Mock Karen
Published: December 2012

A conventional view of regeneration ecology of quaking aspen ( Populus tremuloides Michx.) in western North American holds that reproduction is strictly vegetative and, except on some marginal sites, only successful following high-severity disturbance. This view has strongly influenced silvicultural treatment of western aspen and has led to low expectations concerning genetic diversity of stands and landscapes. However, recent discoveries are fundamentally altering our understanding of western aspen regeneration ecology and genetics. For example, there are clearly multiple pathways of aspen regeneration and stand development. Research on a variety of fronts indicates that seedling establishment is common enough to be ecologically important and that genetic diversity is substantially greater than previously thought. We review conventional understanding of western aspen and put this into the context of silvicultural practice. We then review recent developments in aspen research and assess the silvicultural implications of these insights.
Fire-injured ponderosa pine provide a pulsed resource for bark beetles
Authors: Davis Ryan S. , Hood Sharon , Bentz Barbara J.
Published: December 2012

Bark beetles can cause substantial mortality of trees that would otherwise survive fire injuries. Resin response of fire-injured northern Rocky Mountain ponderosa pine ( Pinus ponderosa Douglas ex P. Lawson & C. Lawson) and specific injuries that contribute to increased bark beetle attack susceptibility and brood production are unknown. We monitored ponderosa pine mortality and resin flow and bark beetle colonization and reproduction following a prescribed fire in Idaho and a wildfire in Montana. The level of fire-caused tree injury differed between the two sites, and the level of tree injury most susceptible to bark beetle attack and colonization also differed. Strip-attacked trees alive 3 years post-fire had lower levels of bole and crown injury than trees mass attacked and killed by bark beetles, suggesting that fire-injured trees were less well defended. Brood production of western pine beetle ( Dendroctonus brevicomis LeConte) did not differ between fire-injured and uninjured trees, although mountain pine beetle ( Dendroctonus ponderosae Hopkins) brood production was low in both tree types, potentially due to competition with faster developing bark beetle species that also colonized trees. Despite a large number of live trees remaining at both sites, bark beetle response to fire-injured trees pulsed and receded within 2 years post-fire, potentially due to a limited number of trees that could be easily colonized.
Systems Biology Technologies Enable Personalized Traditional Chinese Medicine: A Systematic Review
Authors: Wang Xijun , Zhang Aihua , Sun Hui , Wang Ping
Published: December 2012

Traditional Chinese medicine (TCM), an alternative medicine, focuses on the treatment of human disease via the integrity of the close relationship between body and syndrome analysis. It remains a form of primary care in most Asian countries and its characteristics showcase the great advantages of personalized medicine. Although this approach to disease diagnosis, prognosis and treatment has served the medical establishment well for thousands of years, it has serious shortcomings in the era of modern medicine that stem from its reliance on reductionist principles of experimentation and analysis. In this way, systems biology offers the potential to personalize medicine, facilitating the provision of the right care to the right patient at the right time. We expect that systems biology will have a major impact on future personalized therapeutic approaches which herald the future of medicine. Here we summarize current trends and critically review the potential limitations and future prospects of such treatments. Some characteristic examples are presented to highlight the application of this groundbreaking platform to personalized TCM as well as some of the necessary milestones for moving systems biology of a state-of-the-art nature into mainstream health care.
Euonymus alatus in the Treatment of Diabetic Nephropathy in Rats
Authors: Chang Bai , Jin Chuan , Zhang Wei , Kong Li , Yang Ju-Hong , Lian Feng-Mei , Li Qiao-Fen , Yu Bo , Liu Wen-Ke , Yang Ling-Ling , Zhao Ping , Zhen Zhong
Published: December 2012

Diabetic nephropathy is a leading cause of chronic renal failure. Recently, Euonymus alatus showed therapeutic potential in the treatment of diabetes and its chronic complications. In this study, effects of Euonymus alatus and its mechanism in the treatment of diabetic nephropathy were investigated. Diabetic nephropathy was induced in Sprague-Dawley rats by uninephrectomy plus streptozotocin (STZ) administration. Euonymus alatus and irbesartan, as a positive control, were lavaged to these rats for 12 weeks. Our data showed that Euonymus alatus was efficient in lowering HbA1c, improving blood lipids, decreasing 24 h urine protein and protecting kidney function. Pathological studies found kidney damage, including extracellular matrix expansion and glomerulosclerosis, were improved by Euonymus alatus treatment. Further investigation found that the herb had a role in downregulating the expression of transform growth factor β1. In conclusion, Euonymus alatus has a protective role in diabetic nephropathy, which may be related to its downregulation of transform growth factor β1 expression.
1′-Acetoxychavicol Acetate Inhibits Adipogenesis in 3T3-L1 Adipocytes and in High Fat-Fed Rats
Authors: Ohnishi Rie , Matsui-Yuasa Isao , Deguchi Yohei , Yaku Keisuke , Tabuchi Masaki , Munakata Hiroshi , Akahoshi Yasumitsu , Kojima-Yuasa Akiko
Published: December 2012

Alpinia galanga and Languas galanga, which are plants belonging to the ginger family, are frequently used for cooking, especially in Thai and Indonesian cuisine. The compound 1′-acetoxychavicol acetate (ACA), which is naturally obtained from the rhizomes and seeds of these gingers, has antioxidant and anti-inflammatory properties. We investigated the anti-obesity effects of ACA in 3T3-L1 adipocytes and in high fat diet (HFD)-induced rat models of obesity. ACA caused a significant decrease in the activity of GPDH in 3T3-L1 adipocytes without eliciting cell cytotoxicity, and it inhibited cellular lipid accumulation through the down-regulation of transcription factors such as PPARγ and C/EBPα. ACA also induced a dose-dependent phosphorylation of AMP-activated protein kinase (AMPK). In the animal model, rats fed an HFD containing 0.05% ACA gained less weight than rats fed an HFD alone. The visceral fat mass in rats fed an HFD containing 0.05% ACA tended to be lower than that in rats fed an HFD alone. Furthermore, a histological examination of livers from rats fed an HFD showed steatohepatitis. However, rats fed an HFD containing 0.05% ACA showed no histopathological changes in the liver tissue. Our results show that ACA exerts anti-obesity activities both in vitro and in vivo and suggests that ACA may have a novel preventive activity against obesity and possibly other metabolic diseases.
In Vitro Investigation of Anti-Diabetic Effect of Taxus cuspidate Extracts by Ultrasound Assisted Method
Authors: Xiao Linda , Lao Wei-Guo , Tan Yi , Qu Xianqin
Published: December 2012

Extracting active components from Chinese medicinal herbs efficiently is a key step in the investigation of their pharmacological effects and modes of action. In this project, we compared the ultrasound-assisted method and the conventional solvent method for extracting the active compound of Taxus cuspidate (dong bei hong dou shan). Through the analysis of various extractions with a quadruple time-of-fight (Q-TOF) LC/MS, we demonstrated that the ultrasound-assisted method reduced solvent consumption and had shorter extraction time, while the extraction yields of the active compound (taxol) were equivalent to or even higher than those obtained with the conventional solvent extraction method. Through the comparison of Taxus cuspidate extracts (TCEs) with different concentrations of acetone and ethanol, we proved that 50% ethanol was an optimal solvent for extracting taxol from Taxus cuspidate. Based on traditional Chinese medicine (TCM) literature, we further determined whether TCEs possess antidiabetic effects by testing glucose uptake in 3T3-L1 adipocytes treated with TCEs from Taxus cuspidate bark and twigs under insulin stimulation (100 nM). The results showed that neither taxol (10 μg/ml) nor TCEs (1 and 0.1 mg/ml) changed glucose uptake significantly compared with insulin alone. This study demonstrated that the ultrasound-assisted method with 50% ethanol is a highly efficient approach for extracting Taxus cuspidate, which may be applicable for extraction of other Chinese medicinal herbs. Extracts of Taxus cuspidate bark and twigs had no effect on insulin stimulated-glucose uptake in vitro. This result conflicts with the description in TCM literature. Further in vivo study to clarify Taxus cuspidate's metabolic actions is necessary.
NEAR-EXTREMAL BLACK BRANES WITH n3 ENTROPY GROWTH
Authors: HATEFI E. , NURMAGAMBETOV A. J. , PARK I. Y.
Published: December 2012

In this paper, we formulate a criterion for constructing 11D/10D maximal supergravity black-brane solutions with the near-extremal S~n3T5 entropy-temperature relation. We present explicit examples of such solutions with special attention paid to thermodynamics of black M-waves (KK-waves), intersecting/interpolating black-branes with KK-waves, M2/M5 branes and their descents. We find the conditions on charges and numbers of branes in intersections, under which the dielectric effect of brane polarization becomes manifest on the supergravity side. We also briefly discuss the shear viscosity per entropy bound of M5 and D4 black-branes within the AdS/CFT hydrodynamical limit.
EMBEDDED COLLAGEN DEFORMATION MODELS FOR COMPUTATIONAL MODELING OF HEALTHY, KERATOCONIC, AND CROSSLINKED CORNEAS
Authors: FOSTER CRAIG D. , GONGAL DIPKA , BEGAJ TEDI , LUO MICHELLE
Published: December 2012

Collagen plays an extremely important role in carrying forces and maintaining the shape of the cornea. In keratoconus, the cornea shape can become distorted to the extent that normal vision is impossible, and the amount crosslinking between collagen fibrils are generally lower than in healthy eyes. In contrast, riboflavin-induced crosslinks can strengthen and stiffen the cornea. This article examined quantitatively how the extent of crosslinking in collagen fibrils influences the overall mechanical behavior of corneal tissue. Three models for the stress–strain behavior of the fibrils were examined, which is a function of the crosslink density within the fibrils. These models were then embedded in a matrix model, and tensile tests of cornea strips were examined using a finite element program. Results were compared with experiments from the literature for both normal and crosslinked corneas.
A NEW APPROACH FOR SPACE-TIME-MATTER THEORY
Authors: BEJANCU AUREL
Published: December 2012

This is the first paper in a series of three papers on a new approach for space-time-matter (STM) theory. The main purpose of this approach is to replace the Levi-Civita connection on the space-time from the classical Kaluza–Klein theory by what we call the Riemannian horizontal connection on the general Kaluza–Klein space. This is done by a development of a 4D tensor calculus whose geometrical objects live in a 5D space. The 4D tensor calculus and the Riemannian horizontal connection enable us to define in a 5D space some 4D differential operators: horizontal differential, horizontal gradient, horizontal divergence and horizontal Laplacian, which have a great role in the presentation of the STM theory in a covariant form. Finally, we introduce and study the horizontal electromagnetic tensor field, the horizontal Ricci tensor and the horizontal Einstein gravitational tensor field, which replace the well-known tensor fields from the classical Kaluza–Klein theory.
QoS routing in wireless sensor networks—a survey
Authors: Uthra R. Annie , Raja S. V. Kasmir
Published: December 2012

A wireless sensor network (WSN) is a one made up of small sensing devices equipped with processors, memory, and short-range wireless communication. Sensor nodes, are autonomous nodes, which include smart dust sensors, motes and so on. They co-operatively monitor physical or environmental conditions and send the sensed data to the sink node. They differ from traditional computer networks due to resource constraints, unbalanced mixture traffic, data redundancy, network dynamics, and energy balance. These kinds of networks support a wide range of applications that have strong requirements to reduce end-to-end delay and losses during data transmissions. When large numbers of sensors are deployed in a sensor field and are active in transmitting the data, there is a possibility of congestion. Congestion may occur due to buffer overflow, channel contention, packet collision, a high data rate, many to one nature, and so on. This leads to packet loss which causes a decrease in throughput and lifetime. Maximum throughput, energy efficiency and minimum error rate can be achieved by minimizing the congestion. A number of quality of service (QoS) techniques has been developed to improve the quality of the network. This article gives an overview of existing QoS techniques and a parametric comparison made with recent developments. This article mainly concentrates on network congestion in WSN environment.
Ensemble approaches for regression
Authors: Mendes-Moreira João , Soares Carlos , Jorge Alípio Mário , Sousa Jorge Freire De
Published: December 2012

The goal of ensemble regression is to combine several models in order to improve the prediction accuracy in learning problems with a numerical target variable. The process of ensemble learning can be divided into three phases: the generation phase, the pruning phase, and the integration phase. We discuss different approaches to each of these phases that are able to deal with the regression problem, categorizing them in terms of their relevant characteristics and linking them to contributions from different fields. Furthermore, this work makes it possible to identify interesting areas for future research.
Time-series data mining
Authors: Esling Philippe , Agon Carlos
Published: December 2012

In almost every scientific field, measurements are performed over time. These observations lead to a collection of organized data called
time series
. The purpose of time-series data mining is to try to extract all meaningful knowledge from the
shape
of data. Even if humans have a natural capacity to perform these tasks, it remains a complex problem for computers. In this article we intend to provide a survey of the techniques applied for time-series data mining. The first part is devoted to an overview of the tasks that have captured most of the interest of researchers. Considering that in most cases, time-series task relies on the same components for implementation, we divide the literature depending on these common aspects, namely
representation
techniques,
distance
measures, and
indexing
methods. The study of the relevant literature has been categorized for each individual aspects. Four types of robustness could then be formalized and any kind of distance could then be classified. Finally, the study submits various research trends and avenues that can be explored in the near future. We hope that this article can provide a broad and deep understanding of the time-series data mining research field.
In-video product annotation with web information mining
Authors: Li Guangda , Wang Meng , Lu Zheng , Hong Richang , Chua Tat-Seng
Published: December 2012

Product annotation in videos is of great importance for video browsing, search, and advertisement. However, most of the existing automatic video annotation research focuses on the annotation of high-level concepts, such as events, scenes, and object categories. This article presents a novel solution to the annotation of specific products in videos by mining information from the Web. It collects a set of high-quality training data for each product by simultaneously leveraging Amazon and Google image search engine. A visual signature for each product is then built based on the bag-of-visual-words representation of the training images. A correlative sparsification approach is employed to remove noisy bins in the visual signatures. These signatures are used to annotate video frames. We conduct experiments on more than 1,000 videos and the results demonstrate the feasibility and effectiveness of our approach.
Algorithms for stochastic optimization of multicast content delivery with network coding
Authors: Gopinathan Ajay , Li Zongpeng
Published: December 2012

The usage of network resources by content providers is commonly governed by Service-Level Agreements (SLA) between the content provider and the network service provider. Resource usage exceeding the limits specified in the SLA incurs the content provider additional charges, usually at a higher cost. Hence, the content provider's goal is to provision adequate resources in the SLA based on forecasts of future demand. We study capacity purchasing strategies when the content provider employs network coded multicast as the media delivery mechanism, with uncertainty in its future customer set explicitly taken into consideration. The latter requires the content provider to make capacity provisioning decisions based on market predictions and historical customer usage patterns. The probabilistic element suggests a stochastic optimization approach. We model this problem as a two-stage stochastic optimization problem with recourse. Such optimizations are #P-hard to solve directly, and we design two approximation algorithms for them. The first is a heuristic algorithm that exploits properties unique to network coding, so that only polynomial-time operations are needed. It performs well in general scenarios, but the gap from the optimal solution is not bounded by any constant in the worst case. This motivates our second approach, a sampling algorithm partly inspired from the work of Gupta et al. [2004a]. We employ techniques from duality theory in linear optimization to prove that the sampling algorithm provides a 3-approximation to the stochastic multicast problem. We conduct extensive simulations to illustrate the efficacy of both algorithms, and show that the performance of both is usually within 10% of the optimal solution in practice.
Analysis of telemetry data from a real-time strategy game
Authors: Gagné André R. , Seif El-Nasr Magy , Shaw Chris D.
Published: December 2012

This article describes the analysis of a simple, free-to-play real-time strategy (RTS) game called Pixel Legions. In developing this analysis, we worked with the developer to instrument, collect, and analyze telemetry data. The game design questions examined constitute macro- and micro-level analysis. We used pre-existing statistical and visualization tools to examine the macro-level questions. However, micro-level analysis was more game-specific, which required us to develop a novel visualization system to answer these questions in a way that is easy for the designer to understand. Our contribution constitutes the system we built and the analysis we developed to answer the questions imposed by the designer.
A survey of visual, mixed, and augmented reality gaming
Authors: Thomas Bruce H.
Published: December 2012

Visual mixed and augmented realities have historically been applied to the gaming application domain. This article provides a survey of visual mixed and augmented reality gaming in both the academic and commercial contexts. There is an exploration of both indoor and outdoor mixed and augmented reality gaming. The different games are presented via the three major display technologies: head-mounted display, handheld display, and spatial immersive display. A number of academic mixed and augmented reality research projects are described that provide an overview of the current state of the art. A set of example commercial games are also examined to provide the context for the state of the games on the market.
Dynamic resource provisioning for cloud-based gaming infrastructures
Authors: Marzolla Moreno , Ferretti Stefano , D'Angelo Gabriele
Published: December 2012

Modern massively multiplayer online games (MMOGs) allow hundreds of thousands of players to interact with a large, dynamic virtual world. Implementing a scalable MMOG service is challenging because the system is subject to high workload variability, but nevertheless must always operate under very strict quality of service (QoS) requirements. Traditionally, MMOG services are implemented as large dedicated IT infrastructures with aggressive over-provisioning of resources in order to cope with the worst-case workload scenario. In this article we address the problem of building a large-scale, multitier MMOG service using resources provided by a Cloud computing infrastructure. The Cloud paradigm allows customers to request as many resources as they need using a pay-as-you-go model. We harness this paradigm by proposing a dynamic provisioning algorithm, which can resize the resource pool of a MMOG service to adapt to workload variability and maintain a response time below a given threshold. We use a queuing network performance model to quickly estimate the system response time for different configurations. The performance model is used within a greedy algorithm to compute the minimum number of servers to be allocated on each tier in order to satisfy the system response time constraint. Numerical experiments are used to validate the effectiveness of the proposed approach.
Adaptive load-balancing for MMOG servers using KD-trees
Authors: Bezerra Carlos Eduardo B. , Comba João L. D. , Geyer Cláudio F. R.
Published: December 2012

In massively multiplayer online games (MMOGs) there is a great demand for high bandwidth connections with irregular access patterns. Such irregular demand is because players, who can vary from a few hundred to several tens of thousands, often occupy the virtual environment of the game in different ways with varying densities. Hence there is a great need for decentralized architectures with multiple servers that employ load-balancing algorithms to manage regions of the virtual environment. In such systems, each player only connects to the server that manages the region where the player's avatar is located, whereas each server is responsible for mediating the interaction between all pairs of players connected to it. Devising the proper load-balancing algorithm so that it takes spatial and variable occupations into account is a challenging problem which requires adaptive (and possibly dynamic) partitioning of the virtual environment. In this work, we propose the use of a kd-tree for partitioning the game environment into regions, and dynamically adjust the resulting subdivisions based on the distribution of avatars in the virtual environment. We compared our algorithm to competing approaches found in the literature and demonstrated that our algorithm performed better in most aspects we analyzed.
Ubiquity symposium: The science in computer science
Authors: Denning Peter
Published: December 2012

The recent interest in encouraging more middle and high school students to prepare for careers in science, technology, engineering, or mathematics (STEM) has rekindled the old debate about whether computer science is really science. It matters today because computing is such a central field, impacting so many other fields, and yet it is often excluded from high school curricula because it is not seen as a science. In this symposium, fifteen authors examine different aspects from what is science, to natural information processes, to new science-enabled approaches in STEM education.
Sparse methods for biomedical data
Authors: Ye Jieping , Liu Jun
Published: December 2012

Following recent technological revolutions, the investigation of massive biomedical data with growing scale, diversity, and complexity has taken a center stage in modern data analysis. Although complex, the underlying representations of many biomedical data are often sparse. For example, for a certain disease such as leukemia, even though humans have tens of thousands of genes, only a few genes are relevant to the disease; a gene network is sparse since a regulatory pathway involves only a small number of genes; many biomedical signals are sparse or compressible in the sense that they have concise representations when expressed in a proper basis. Therefore, finding sparse representations is fundamentally important for scientific discovery. Sparse methods based on the '1 norm have attracted a great amount of research efforts in the past decade due to its sparsity-inducing property, convenient convexity, and strong theoretical guarantees. They have achieved great success in various applications such as biomarker selection, biological network construction, and magnetic resonance imaging. In this paper, we review state-of-the-art sparse methods and their applications to biomedical data.
Supervised patient similarity measure of heterogeneous patient records
Authors: Sun Jimeng , Wang Fei , Hu Jianying , Edabollahi Shahram
Published: December 2012

Patient similarity assessment is an important task in the context of patient cohort identif cation for comparative effectiveness studies and clinical decision support applications. The goal is to derive clinically meaningful distance metric to measure the similarity between patients represented by their key clinical indicators. How to incorporate physician feedback with regard to the retrieval results? How to interactively update the underlying similarity measure based on the feedback? Moreover, often different physicians have different understandings of patient similarity based on their patient cohorts. The distance metric learned for each individual physician often leads to a limited view of the true underlying distance metric. How to integrate the individual distance metrics from each physician into a globally consistent unif ed metric?

We describe a suite of supervised metric learning approaches that answer the above questions. In particular, we present Locally Supervised Metric Learning (LSML) to learn a generalized Mahalanobis distance that is tailored toward physician feedback. Then we describe the interactive metric learning (iMet) method that can incrementally update an existing metric based on physician feedback in an online fashion. To combine multiple similarity measures from multiple physicians, we present Composite Distance Integration (Comdi) method. In this approach we f rst construct discriminative neighborhoods from each individual metrics, then combine them into a single optimal distance metric. Finally, we present a clinical decision support prototype system powered by the proposed patient similarity methods, and evaluate the proposed methods using real EHR data against several baselines.
Cross domain similarity mining
Authors: Dong Guozhu
Published: December 2012

This paper defines the cross domain similarity mining (CDSM) problem, and motivates CDSM with several potential applications. CDSM has big potential in (1) supporting understanding transfer and (2) supporting research by analogy, since similarity is vital to understanding/meaning and to identifying analogy, and since analogy is a fundamental approach frequently used in hypothesis generation and in research. CDSM also has big potential in (3) advancing learning transfer since cross domain similarities can shed light on how to best adapt classifiers/clusterings across given domains and how to avoid negative transfer. CDSM can also be useful for (4) solving the schema/ontology matching problem. Moreover, this paper gives a list of potential research questions for CDSM, and compares CDSM with related studies. One purpose of this paper is to introduce the CDSM problem to the wide KDD community in order to quickly realize the full potential of CDSM.
Efficient architecture and scheduling technique for pairwise sequence alignment
Authors: Isa M. N. , Benkrid K. , Clayton T.
Published: December 2012

A novel efficient hardware architecture to optimize the execution time of dynamic programming-based (DP) pairwise sequence alignment algorithms in hardware is proposed. It is realized by introducing an efficient overlapped scheduling of alignment matrix computation and substitution coefficients' pre-loading onto processing elements (PEs) in folded systolic arrays. A new metric is also proposed as an independent performance evaluator to compare different core implementations on different FPGA platforms fairly. Implementation results show that the new hardware architecture for sequence alignment achieves a minimum of 40 percent area normalized speed-up compared to the state-of-the-art hardware implementation, with the speed-up growing linearly with the number of folds e.g. 120 percent speed-up for 16-fold. Compared to equivalent software implementations, the novel hardware architecture achieves a minimum of 103x speed-up, with the speed-up growing linearly with the number of folds e.g. 140x speed-up for 20-fold.
A new high radix-2
r
(r≥8) multibit recoding algorithm for large operand size (N≥32) multipliers
Authors: Oudjida A. K. , Chaillet N. , Berrandjia M. L. , Liacha A.
Published: December 2012

This paper addresses the problem of multiplication with large operand sizes (N≥32). We propose a new recursive recoding algorithm that shortens the critical path of the multiplier and reduces the hardware complexity of partial-product-generators as well. The new recoding algorithm provides an optimal space/time partitioning of the multiplier architecture for any size N of the operands. As a result, the critical path is drastically reduced to 3
3
√ N / 2 -- 3 with no area overhead in comparison to modified Booth algorithm that shows a critical path of N/2 in adder stages. For instance, only 7 adder stages are needed for a 64-bit two's complement multiplier. Confronted to reference algorithms for N=64, important gain ratios of 1.62, 1.71, 2.64 are obtained in terms of multiply-time, energy consumption per multiplyoperation, and total gate count, respectively.
Prevalence, Demographics, and Treatment Characteristics of Visual Impairment due to Diabetic Macular Edema in a Representative Canadian Cohort
Authors: Petrella Robert J. , Blouin Julie , Davies Brian , Barbeau Martin
Published: December 2012

Diabetic macular edema (DME) is the leading cause of blindness in the diabetic population. However, there is limited understanding of the epidemiology of DME with visual impairment (VI) and treatment in patients with diabetes in Canada. This observational, retrospective study used records from the Southwestern Ontario database to observe the demographics, prevalence, and treatment characteristics of VI due to DME compared to a healthy population in a real-world Canadian setting. Data was compared between a cohort of 8,368 diabetic (type 1 or 2) patients, who were ≥18 years old and had a diagnosis of DME with VI (visual acuity <20/40 in Snellen equivalent), and 76,077 age- and gender-matched subjects representing a healthy population. Among diabetic patients, prevalence of DME was 15.7%, and prevalence of VI due to DME was 2.56%. Laser monotherapy was the most frequently used treatment. Public funding covered costs for 85% of persons with DME while 18% were paid for with private funds. This study provides insight into the demographics, prevalence, and treatment of VI due to DME in a representative Canadian cohort. This data can help to inform evaluation of current DME treatment patterns and of proposed new treatment on drug plan budgets in Canada.
An Adaptive Variable Structure Control Scheme for Underactuated Mechanical Manipulators
Authors: Yang Jung Hua , Yang Kuang Shine
Published: December 2012

Mechanical arms have been widely used in the industry for many decades. They have played a dominant role in factory automation. However the control performance, or even system stability, would be deteriorated if some of the actuators fail during the operations. Hence, in this study, an adaptive variable structure scheme is presented to solve this problem. It is shown that, by applying the control mechanism proposed in this paper, the motion of robot systems can maintain asymptotical stability in case of actuators failure. The control algorithms as well as the convergence analysis are theoretically proved based on Lyapunov theory. In addition, to demonstrate the validity of the controller, a number of simulations as well as real‐time experiments are also performed for Pendubot robot and Furuta robot systems. The results confirm the applicability of the proposed controller.
Direct Index Method of Beam Damage Location Detection Based on Difference Theory of Strain Modal Shapes and the Genetic Algorithms Application
Authors: Zhenming Bao , Deyou Zhao , Zhe Lin , Jun Ma , Yaobao Zhen
Published: December 2012

Structural damage identification is to determine the structure health status and analyze the test results. The three key problems to be solved are as follows: the existence of damage in structure, to detect the damage location, and to confirm the damage degree or damage form. Damage generally changes the structure physical properties (i.e., stiffness, mass, and damping) corresponding with the modal characteristics of the structure (i.e., natural frequencies, modal shapes, and modal damping). The research results show that strain mode can be more sensitive and effective for local damage. The direct index method of damage location detection ISMSD is based on difference theory, without the modal parameter of the original structure. FEM numerical simulation to partial crack with different degree is done. The criteria of damage location detection can be obtained by strain mode difference curve through cubic spline interpolation. Also the genetic algorithm box in Matlab is used. It has been possible to identify the damage to a reasonable level of accuracy.
Heat Shock Proteins: Pathogenic Role in Atherosclerosis and Potential Therapeutic Implications
Authors: Kilic Arman , Mandal Kaushik
Published: December 2012

Heat shock proteins (HSPs) are a highly conserved group of proteins that are constitutively expressed and function as molecular chaperones, aiding in protein folding and preventing the accumulation of misfolded proteins. In the arterial wall, HSPs have a protective role under normal physiologic conditions. In disease states, however, HSPs expressed on the vascular endothelial cell surface can act as targets for detrimental autoimmunity due to their highly conserved sequences. Developing therapeutic strategies for atherosclerosis based on HSPs is challenged by the need to balance such physiologic and pathologic roles of these proteins. This paper summarizes the role of HSPs in normal vascular wall processes as well as in the development and progression of atherosclerosis. The potential implications of HSPs in clinical therapies for atherosclerosis are also discussed.
Isolated Central Sulcus Hemorrhage: A Rare Presentation Most Frequently Associated with Cerebral Amyloid Angiopathy
Authors: Chamarthy Murthy R. , Kumar Yogesh , Meszaros Michael D. , Shah Ankit , Rosovsky Mark A.
Published: December 2012

Central sulcus hemorrhage is a rare imaging finding that can be related to cerebral amyloidosis in a normotensive non-traumatic elderly patient and present as an isolated finding or in association with other areas of involvement. We report a case presenting with an isolated central sulcus hemorrhage on computed tomography. Further imaging work-up excluded other potential causes of peripheral hemorrhages and established a putative diagnosis of cerebral amyloidosis.
Decomposition of the Time Reversal Operator for Target Detection
Authors: Li Chun-xiao , Lu Huan-cai , Guo Ming-fei , Zhao Hang-fang , Jin Jiang-ming
Published: December 2012

A thorough theory of detection problem using active time reversal has been investigated in several recent papers. Although active time reversal method is theoretically superior to the others, its practical implementation for target detection is far more difficult. This paper investigates the detection problem using passive decomposition of the time reversal operator (DORT) method. Provided that the signal components can be modeled as a linear combination of basis vectors with an unknown signal subspace, the generalized likelihood ratio test (GLRT) is derived based on Neyman‐Person lemma with the unknown signal subspace replaced by its maximum likelihood estimation. The test statistics is one of the dominant eigenvalues of the time reversal operator for a point‐like scatterer. Finally, the performance of the DORT detector is investigated with acoustic data collected from a waveguide tank. The experimental results show that the DORT detector can provide, respectively, 1.4 dB, 1.1 dB, and 0.8 dB performance gains over the energy detector given false alarms rate of 0.0001, 0.001, and 0.01.
Nonsurgical Endodontic Retreatment of Advanced Inflammatory External Root Resorption Using Mineral Trioxide Aggregate Obturation
Authors: Utneja Shivani , Garg Gaurav , Arora Shipra , Talwar Sangeeta
Published: December 2012

Inflammatory external root resorption is one of the major complications after traumatic dental injury. In this case report, we describe treatment of a maxillary central incisor affected by severe, perforating external root resorption. An 18-year-old patient presented with a previously traumatized, root-filled maxillary central incisor associated with pain and sinus tract. Radiographic examination revealed periradicular lesion involving pathologic resorption of the apical region of the root and lateral root surface both mesially and distally. After removal of the root canal filling, the tooth was disinfected with intracanal triple antibiotic paste for 2 weeks. The antibiotic dressing was then removed, and the entire root canal was filled with mineral trioxide aggregate. The endodontic access cavity was restored with composite resin. After 18 months, significant osseous healing of the periradicular region and lateral periodontium had occurred with arrest of external root resorption, and no clinical symptoms were apparent.