bluuebunny/crossref_metadata_2025 huggingface dataset:
Late Holocene glacial activity at Bromley Glacier, Cambria Icefield, northern British Columbia Coast Mountains, Canada
Authors: Hoffman Kira M. , Smith Dan J.
Published: January 2013

Retreating and downwasting glaciers in the British Columbia Coast Mountains are exposing the remains of forests buried during Holocene-age glacial advances. Despite recent progress in discerning the extent of these advances in the Pacific and Kitimat ranges of the southern and central Coast Mountains, comparatively little is known about the character of these advances in the Boundary Ranges of northwestern British Columbia. This research uses dendroglaciologic and radiocarbon analyses to describe late Holocene glacial advances at Bromley Glacier in the Cambria Icefield area. Four intervals of glacial expansion were identified at ca. 2470–2410, 1850, 1450, and 830 14C years BP. Absent were wood remains associated with mid-Holocene episodes of glacier expansion recorded at nearby sites. The late Holocene deposits described at Bromley Glacier are contemporaneous with those found at other glaciers in the southern Boundary Ranges and contribute to a growing understanding of the synchronous response of glaciers in this region to mass balance fluctuations during the Holocene.
Improving tree selection for partial cutting through joint probability modelling of tree vigor and quality
Authors: Pothier David , Fortin Mathieu , Auty David , Delisle-Boulianne Simon , Gagné Louis-Vincent , Achim Alexis
Published: January 2013

Tree classification systems are generally designed to predict the supply of high-quality logs for the wood processing industries and to mark defective trees for removal with the aim of improving both the vigor and quality of future stands. Although these two objectives are generally inversely related, their joint consideration could enable the development of robust criteria for improved tree selection in partial cuttings of northern hardwood stands by targeting low-vigor (LV) trees of high quality (HQ). In this study, we used a copula approach to model the joint probability distribution of trees characterized by both vigor and quality, which accounts for the statistical dependence between the different classes of both classification systems. The relationships between the probability of occurrence of a tree in each joint category and tree diameter at breast height (DBH) were quite similar among the three studied species: yellow birch (Betula alleghaniensis Britt.), sugar maple (Acer saccharum Marsh.), and American beech (Fagus grandifolia Ehrh.). In particular, the probability of occurrence of LV–HQ trees was characterized by a parabolic curve with a maximum value attained at the mid-DBH range, whereas that of LV and low-quality (LQ) trees increased with increasing DBH. This suggests that instead of harvesting large and mostly LV–LQ trees, partial cutting should target smaller LV–HQ trees, so that the volume of harvested HQ trees would increase without compromising the silvicultural objective of improving the vigor of future stands.
Correcting the nondetection bias of angle count sampling
Authors: Ritter Tim , Nothdurft Arne , Saborowski Joachim
Published: January 2013

The well-known angle count sampling (ACS) has proved to be an efficient sampling technique and has been applied in forest inventories for many decades. However, ACS assumes total visibility of objects; any violation of this assumption leads to a nondetection bias. We present a novel approach, in which the theory of distance sampling is adapted to traditional ACS to correct for the nondetection bias. Two new estimators were developed based on expanding design-based inclusion probabilities by model-based estimates of the detection probabilities. The new estimators were evaluated in a simulation study as well as in a real forest inventory. It is shown that the nondetection bias of the traditional estimator is up to −52.5%, whereas the new estimators are approximately unbiased.
Temperature-dependent reorientation dynamics of laser dyes in alkane and alcohol solvents
Authors: Nadaf Y.F. , Renuka C.G. , Raikar U.S.
Published: January 2013

The rotational dynamics of similar sized coumarin 6 (C6), coumarin 7 (C7), and coumarin 30 (C30) laser dyes has been studied in alkane and alcohol solvents using steady-state and time-resolved fluorescence depolarization methods. The estimated rotational reorientation times of these probes are observed to vary linearly as a function of viscosity over the range of temperatures studied. It is found that the rotational reorientation time measurements of these molecules in alcohol and alkane typically have relaxation times on the order of picoseconds. The rotational reorientation times of the C7 molecule are greater than those of the C6 and C30 molecules. It was observed that C7 rotates faster in both the solvents than C6 and C30, indicating that the effects of the medium and structural differences of molecules lead to slower rotation.
Massless fermion quasinormal modes in the Horava–Lifshitz background
Authors: Sadeghi J. , Pourhassan B. , Jafarzadeh K. , Reisi E. , Rostami M.
Published: January 2013

In this paper we consider the Horava–Lifshitz background and obtain the massless fermion quasinormal modes. In that case we use the Newman–Penrose formalism and the massless Dirac equation to calculate the radial and angular parts of equations. The wave function and corresponding modes can be obtained using the factorization method.
Quercetin prevents experimental glucocorticoid-induced osteoporosis: a comparative study with alendronate
Authors: Derakhshanian Hoda , Djalali Mahmoud , Djazayery Abolghassem , Nourijelyani Keramat , Ghadbeigi Sajad , Pishva Hamideh , Saedisomeolia Ahmad , Bahremand Arash , Dehpour Ahmad Reza
Published: January 2013

Glucocorticoid-induced osteoporosis (GIO) is the most common type of secondary osteoporosis. The aim of this study was to compare the efficacy of quercetin, a plant-derived flavonoid, with alendronate in the prevention of GIO. Fifty-six Sprague–Dawley rats were randomly distributed among 7 groups (8 rats per group) and treated for 6 weeks with one of the following: (i) normal saline; (ii) 40 mg methylprednisolone sodium succinate (MP)/kg body mass; (iii) MP + 40 μg alendronate/kg; (iv) MP + 50 mg quercetin/kg; (v) MP + 40 μg alendronate/kg + 50 mg quercetin/kg; (vi) MP + 150 mg quercetin/kg; and (vii) MP + 40 μg alendronate/kg + 150 mg quercetin/kg. MP and alendronate were injected subcutaneously and quercetin was administered by oral gavage 3 days a week. At the end of the study, femur breaking strength was significantly decreased as a consequence of MP injection. This decrease was completely compensated for in groups receiving 50 mg quercetin/kg plus alendronate, and 150 mg quercetin/kg with or without alendronate. Quercetin noticeably elevated osteocalcin as a bone formation marker, while alendronate did not show such an effect. In addition, administration of 150 mg quercetin/kg increased femoral trabecular and cortical thickness by 36% and 22%, respectively, compared with the MP-treated group. These data suggest that 150 mg quercetin/kg, alone or in combination with alendronate, can completely prevent GIO through its bone formation stimulatory effect.
Clinical Research of Traditional Chinese Medical Intervention on Impaired Glucose Tolerance
Authors: Gao Yanbin , Zhou Hui , Zhao Huiling , Feng Xingzhong , Feng Jianhua , Li Yi , Zhang Hong , Lu Hao , Qian Qiuhai , Yu Xiuchen , Zhang Ning , Yu Jiangyi , Ni Qing , Pan Mingzheng
Published: January 2013

To identify a safe and effective Impaired Glucose Tolerance (IGT) intervention program using Traditional Chinese Medicine (TCM) supported by Standard Health Care Advice (SHCA) for the evidence-based TCM intervention in IGT and evidence-based prevention of type 2 diabetes. A total of 510 IGT patients were randomly assigned into either control or TCM intervention group (255 patients for each group). The control group received standard health care according to SHCA. The intervention group also received TCM intervention in addition to standard health care. The study was conducted over a three-year follow-up. At the end of three years follow-up, accumulative incidence and average annual incidence rate of diabetes in the control group was 43.86% and 14.62% respectively. Accumulative incidence and average annual incidence rate of diabetes in the TCM intervention group was 22.17% and 7.39% respectively. Compared with the control treatment, TCM intervention can reduce the relative risk of IGT patients progressing to type 2 diabetes by 49.45% and absolute risk by 21.69%. In the TCM intervention group, oral glucose tolerance test (OGTT), 2 h glucose, glycated hemoglobin, insulin resistance and body mass index were all significantly improved when compared to the control group. No significant side effect was observed during the follow-up in the TCM group. The SHCA-supported TCM intervention can reduce the conversion rate of IGT to diabetes and improve insulin resistance; therefore, it is a safe and effective IGT intervention strategy.
Effects of Tai Chi on the Protracted Abstinence Syndrome: A Time Trial Analysis
Authors: Li De-Xiang , Zhuang Xin-Ying , Zhang Yi-Ping , Guo Hao , Wang Ze , Zhang Qing , Feng Yue-Mei , Yao Yong-Gang
Published: January 2013

While exercise has been shown to reduce the negative effects of substance withdrawal symptoms, no research has investigated if Tai Chi, a traditional Chinese exercise, has similar effects. Here, we observed the physiological effects of Tai Chi on protracted abstinence syndrome (PAS) in female heroin addicts by comprehensively inspecting their immune system function, complete blood count, hepatic function and renal function. To determine the psychological effects, we used the Hamilton Rating Scale for Depression (HRSD) and the rating scale of heroin withdrawal symptoms. We recruited 70 heroin-addicted young women beginning to undergo withdrawal and randomly assigned them into two groups: one group received one-hour Tai Chi exercise every two days (Tai Chi group, n = 36) and the other group did not (control group, n = 34). Thirty-three patients finished this six-month trial. Numerous significant physiological differences were observed between all heroin-addicted subjects (n = 70) and age-matched healthy individuals (n = 18), suggesting a deleterious effect of drug addiction. There were improvements for certain physical parameters between the Tai Chi group (n = 17) and the control group (n = 16), although the differences were not statistically significant. We observed a small significant difference in psychological effects near the 60-day mark between the two groups. Taken together, our results suggest that Tai Chi might have a positive effect on PAS, which future studies can confirm by using an expanded sample size, longer trial time, and more sensitive and specific indicators of psychological and physiological health.
Proteomic Changes Induced by Podophyllotoxin in Human Cervical CarcinomaHeLaCells
Authors: Wang Bochan , Chen Lifeng , Zhen Hong , Zhou Li , Shi Ping , Huang Zhiwei
Published: January 2013

Podophyllotoxin, a kind of lignan extracted from the Podophyllum plant, has been shown to inhibit the growth of various carcinoma cells. However, the molecular mechanism remains unclear. In this study, the inhibition of cell growth and changes in protein expression induced by podophyllotoxin were investigated in human cervical carcinoma HeLa cells. Our results demonstrate that Podophyllotoxin inhibits HeLa cell growth and induces apoptosis. By using proteomic techniques, seven proteins were found to be significantly regulated by podophyllotoxin compared to the untreated control; among them, four were down-regulated and three were up-regulated. All of the seven proteins were identified with peptide mass fingerprinting using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) after in-gel trypsin digestion. Five of these proteins are involved in protein metabolism, and the other two play roles in cell communication and signaling transduction pathways. It is suggested that the effect of podophyllotoxin on the growth of tumor cells is significantly related to the metabolism-associated proteins.
Screening and Analyzing the Potential Bioactive Components from Reduning Injection, Using Macrophage Cell Extraction and Ultra-High Performance Liquid Chromatography Coupled with Mass Spectrometry
Authors: Li Yonghui , Wang Peixiang , Xiao Wei , Zhao Li , Wang Zhenzhong , Yu Li
Published: January 2013

In this paper, a useful method for screening and analyzing the potential bioactive components from Reduning Injection was developed using macrophage cell extraction and ultra-high performance liquid chromatography coupled with Q-TOF/MS spectrometry. In addition, the protective effects on macrophage cell damage induced by LPS in vitro were also investigated. The results showed that chlorogenic acid, 3, 4-dicaffeoylquinic acid, 3, 5-dicaffeoylquinic acid and 4, 5-dicaffeoylquinic acid significantly inhibited the prostaglandin E2 (PGE2) release and reversed the interleukin-6 (IL-6) secretion of macrophages (p < 0.05). These data indicated that the method of macrophage cell extraction coupled with UPLC-MS technology is feasible, rapid and useful for screening and analyzing potential bioactive components from TCM injection.
A ROBUST 900 MHz RFID READER CHIP WITH RC-CALIBRATION
Authors: SHOUXIAN MOU , KAIXUE MA , KIAT SENG YEO
Published: January 2013

A fully integrated RFID reader chip targeted to operate in the frequency range of 860 MHz to 960 MHz is designed, simulated and fabricated. To reduce the chip performance degradation due to process and temperature variation, resistor and capacitor calibration is adopted. The output codes of resistor calibration are used to adjust main circuit blocks' biasing current while the output codes of capacitor calibration are used to fine tune filter bandwidth and Digital-to-analog converter (DAC) conversion accuracy. Dual-tuned magnetic coupled LC tanks are also introduced in our VCO design to improve phase noise performance and extend tuning range, so as to enhance the robustness of the proposed RFID reader system. The reader is implemented with a low cost 90 nm standard CMOS process and has a chip area of 3.1 mm by 3.3 mm. The chip is packaged with QFN48 and tested on PCB. The proposed RFID reader consumes 90 mW of power and has robust performance against temperature, voltage supply and process variation. The merits of the chip make it ideal for various application scenarios.
SYNCHRONIZATION OF CLOCKS COUPLED BY NEUROTRANSMITTER IN THE SCN
Authors: LI YING , LIU ZENGRONG
Published: January 2013

In mammals, the suprachiasmatic nucleus (SCN) of the hypothalamus is considered as the master circadian pacemaker. Each cell in the SCN contains an autonomous molecular clock, and the SCN is composed of multiple single-cell circadian oscillators. The fundamental question is how the individual cellular oscillators, expressing a wide range of periods, interact and assemble to achieve phase synchronization. In natural conditions, the interaction between the SCN neurons is non-negligible and coupling between cells in the SCN is achieved partly by neurotransmitters. Though there have been a lot of works about the synchronization of circadian oscillators coupled by neurotransmitter, most of the works are based on numerical simulation with little theoretical analysis. In this paper, from the theoretical analysis, we prove that the clocks can be synchronized by the neurotransmitter with mathematical knowledge. Our results also show that the coupling among neurons can synchronize circadian oscillators but the synchronized oscillators are not with period of 24 h, which indicates that environmental cues are necessary to entrain oscillators with period of 24 h. This work can offer theoretical basis to study circadian synchronization in a numerical or experimental way.
PHONON DRAG AND CARRIER DIFFUSION CONTRIBUTIONS IN THERMOELECTRIC POWER OF K3C60 FULLERIDES
Authors: VARSHNEY DINESH , JAIN RAJENDRA , SINGH NAMITA
Published: January 2013

The thermoelectric power (S) of K3C60 fullerides is theoretically analyzed. Mott expression within parabolic band approximation is used to reveal the electron diffusive thermoelectric power (Sc diff ) following Fermi energy as electron parameter, Sc diff show linear temperature dependence. S infers a change in slope above transition temperature and become almost linear above 70 K. The phonon drag thermoelectric power (S ph drag ) is computed within relaxation time approximation when thermoelectric power is limited by scattering of phonons from defects, grain boundaries, phonons and electrons as carriers. The S ph drag of K3C60 is anomalous and it is an artifact of strong phonon-electron and phonon scattering mechanism. The thermoelectric power within relaxation time approximation has been taken into account ignoring a possible energy dependence of the scattering rates. Behaviour of S(T) is determined by competition among the several operating scattering mechanisms for the heat carriers and a balance between carrier diffusion and phonon drag contributions.
Feedback-driven binary code diversification
Authors: Coppens Bart , De Sutter Bjorn , Maebe Jonas
Published: January 2013

As described in many blog posts and in the scientific literature, exploits for software vulnerabilities are often engineered on the basis of patches. For example, “Microsoft Patch Tuesday” is often followed by “Exploit Wednesday” during which yet unpatched systems become vulnerable to patch-based exploits. Part of the patch engineering includes the identification of the vulnerable binary code by means of reverse-engineering tools and diffing add-ons. In this article we present a feedback-driven compiler tool flow that iteratively transforms code until diffing tools become ineffective enough to close the “Exploit Wednesday” window of opportunity. We demonstrate the tool's effectiveness on a set of real-world patches and against the latest version of BinDiff.
Per-thread cycle accounting in multicore processors
Authors: Du Bois Kristof , Eyerman Stijn , Eeckhout Lieven
Published: January 2013

While multicore processors improve overall chip throughput and hardware utilization, resource sharing among the cores leads to unpredictable performance for the individual threads running on a multicore processor. Unpredictable per-thread performance becomes a problem when considered in the context of multicore scheduling: system software assumes that all threads make equal progress, however, this is not what the hardware provides. This may lead to problems at the system level such as missed deadlines, reduced quality-of-service, non-satisfied service-level agreements, unbalanced parallel performance, priority inversion, unpredictable interactive performance, etc.

This article proposes a hardware-efficient per-thread cycle accounting architecture for multicore processors. The counter architecture tracks per-thread progress in a multicore processor, detects how inter-thread interference affects per-thread performance, and predicts the execution time for each thread if run in isolation. The counter architecture captures the effects of additional conflict misses due to cache sharing as well as increased latency for other memory accesses due to resource and bandwidth contention in the memory subsystem. The proposed method accounts for 74.3% of the interference cycles, and estimates per-thread progress within 14.2% on average across a large set of multi-program workloads. Hardware cost is limited to 7.44KB for an 8-core processor, a reduction by almost 10× compared to prior work while being 63.8% more accurate. Making system software progress aware improves fairness by 22.5% on average over progress-agnostic scheduling.
Maxine
Authors: Wimmer Christian , Haupt Michael , Van De Vanter Michael L. , Jordan Mick , Daynès Laurent , Simon Douglas
Published: January 2013

A highly productive platform accelerates the production of research results. The design of a Virtual Machine (VM) written in the Java™ programming language can be simplified through exploitation of interfaces, type and memory safety, automated memory management (garbage collection), exception handling, and reflection. Moreover, modern Java IDEs offer time-saving features such as refactoring, auto-completion, and code navigation. Finally, Java annotations enable compiler extensions for low-level “systems programming” while retaining IDE compatibility. These techniques collectively make complex system software more “approachable” than has been typical in the past.

The Maxine VM, a metacircular Java VM implementation, has aggressively used these features since its inception. A co-designed companion tool, the Maxine Inspector, offers integrated debugging and visualization of all aspects of the VM's runtime state. The Inspector's implementation exploits advanced Java language features, embodies intimate knowledge of the VM's design, and even reuses a significant amount of VM code directly. These characteristics make Maxine a highly approachable VM research platform and a productive basis for research and teaching.
A decoupled local memory allocator
Authors: Diouf Boubacar , Hantaş Can , Cohen Albert , Özturk Özcan , Palsberg Jens
Published: January 2013

Compilers use software-controlled local memories to provide fast, predictable, and power-efficient access to critical data. We show that the local memory allocation for straight-line, or linearized programs is equivalent to a weighted interval-graph coloring problem. This problem is new when allowing a color interval to “wrap around,” and we call it the submarine-building problem. This graph-theoretical decision problem differs slightly from the classical ship-building problem, and exhibits very interesting and unusual complexity properties. We demonstrate that the submarine-building problem is NP-complete, while it is solvable in linear time for not-so-proper interval graphs, an extension of the the class of proper interval graphs. We propose a clustering heuristic to approximate any interval graph into a not-so-proper interval graph, decoupling spill code generation from local memory assignment. We apply this heuristic to a large number of randomly generated interval graphs reproducing the statistical features of standard local memory allocation benchmarks, comparing with state-of-the-art heuristics.
Compiler support for lightweight context switching
Authors: Dolan Stephen , Muralidharan Servesh , Gregg David
Published: January 2013

We propose a new language-neutral primitive for the LLVM compiler, which provides efficient context switching and message passing between lightweight threads of control. The primitive, called Swapstack, can be used by any language implementation based on LLVM to build higher-level language structures such as continuations, coroutines, and lightweight threads. As part of adding the primitives to LLVM, we have also added compiler support for passing parameters across context switches. Our modified LLVM compiler produces highly efficient code through a combination of exposing the context switching code to existing compiler optimizations, and adding novel compiler optimizations to further reduce the cost of context switches. To demonstrate the generality and efficiency of our primitives, we add one-shot continuations to C++, and provide a simple fiber library that allows millions of fibers to run on multiple cores, with a work-stealing scheduler and fast inter-fiber sychronization. We argue that compiler-supported lightweight context switching can be significantly faster than using a library to switch between contexts, and provide experimental evidence to support the position.
Exploiting reuse locality on inclusive shared last-level caches
Authors: Albericio Jorge , Ibáñez Pablo , Viñals Víctor , Llabería Jose María
Published: January 2013

Optimization of the replacement policy used for Shared Last-Level Cache (SLLC) management in a Chip-MultiProcessor (CMP) is critical for avoiding off-chip accesses. Temporal locality, while being exploited by first levels of private cache memories, is only slightly exhibited by the stream of references arriving at the SLLC. Thus, traditional replacement algorithms based on recency are bad choices for governing SLLC replacement. Recent proposals involve SLLC replacement policies that attempt to exploit reuse either by segmenting the replacement list or improving the rereference interval prediction.

On the other hand, inclusive SLLCs are commonplace in the CMP market, but the interaction between replacement policy and the enforcement of inclusion has barely been discussed. After analyzing that interaction, this article introduces two simple replacement policies exploiting reuse locality and targeting inclusive SLLCs:
Least Recently Reused
(LRR) and
Not Recently Reused
(NRR). NRR has the same implementation cost as NRU, and LRR only adds one bit per line to the LRU cost.

After considering reuse locality and its interaction with the invalidations induced by inclusion, the proposals are evaluated by simulating multiprogrammed workloads in an 8-core system with two private cache levels and an SLLC. LRR outperforms LRU by 4.5% (performing better in 97 out of 100 mixes) and NRR outperforms NRU by 4.2% (performing better in 99 out of 100 mixes). We also show that our mechanisms outperform rereference interval prediction, a recently proposed SLLC replacement policy and that similar conclusions can be drawn by varying the associativity or the SLLC size.
Algorithmic species
Authors: Nugteren Cedric , Custers Pieter , Corporaal Henk
Published: January 2013

Code generation and programming have become ever more challenging over the last decade due to the shift towards parallel processing. Emerging processor architectures such as multi-cores and GPUs exploit increasingly parallelism, requiring programmers and compilers to deal with aspects such as threading, concurrency, synchronization, and complex memory partitioning. We advocate that programmers and compilers can greatly benefit from a structured classification of program code. Such a classification can help programmers to find opportunities for parallelization, reason about their code, and interact with other programmers. Similarly, parallelising compilers and source-to-source compilers can take threading and optimization decisions based on the same classification. In this work, we introduce
algorithmic species
, a classification of affine loop nests based on the polyhedral model and targeted for both automatic and manual use. Individual classes capture information such as the structure of parallelism and the data reuse. To make the classification applicable for manual use, a basic vocabulary forms the base for the creation of a set of intuitive classes. To demonstrate the use of algorithmic species, we identify 115 classes in a benchmark set. Additionally, we demonstrate the suitability of algorithmic species for automated uses by showing a tool to automatically extract species from program code, a species-based source-to-source compiler, and a species-based performance prediction model.
An integrated pseudo-associativity and relaxed-order approach to hardware transactional memory
Authors: Yan Zhichao , Jiang Hong , Tan Yujuan , Feng Dan
Published: January 2013

Our experimental study and analysis reveal that the bottlenecks of existing hardware transactional memory systems are largely rooted in the extra data movements in version management and in the inefficient scheduling of conflicting transactions in conflict management, particularly in the presence of high-contention and coarse-grained applications. In order to address this problem, we propose an integrated Pseudo-Associativity and Relaxed-Order approach to hardware Transactional Memory, called PARO-TM. It exploits the extra pseudo-associative space in the data cache to hold the new value of each transactional modification, and maintains the mappings between the old and new versions via an implicit pseudo-associative hash algorithm (i.e., by inverting the specific bit of the SET index). PARO-TM can branch out the speculative version from the old version upon each transactional modification on demand without a dedicated hardware component to hold the uncommitted data. This means that it is able to automatically access the proper version upon the transaction's commit or abort. Moreover, PARO-TM augments multi-version support in a chained directory to schedule conflicting transactions in a relaxed-order manner to further reduce their overheads. We compare PARO-TM with the state-of-the-art LogTM-SE, TCC, DynTM, and SUV-TM systems and find that PARO-TM consistently outperforms these four representative HTMs. This performance advantage of PARO-TM is far more pronounced under the high-contention and coarse-grained applications in the STAMP benchmark suite, for which PARO-TM is motivated and designed.
Dynamic code duplication with vulnerability awareness for soft error detection on VLIW architectures
Authors: Lee Jongwon , Ko Yohan , Lee Kyoungwoo , Youn Jonghee M. , Paek Yunheung
Published: January 2013

Soft errors are becoming a critical concern in embedded system designs. Code duplication techniques have been proposed to increase the reliability in multi-issue embedded systems such as VLIW by exploiting empty slots for duplicated instructions. However, they increase code size, another important concern, and ignore vulnerability differences in instructions, causing unnecessary or inefficient protection when selecting instructions to be duplicated under constraints. In this article, we propose a compiler-assisted dynamic code duplication method to minimize the code size overhead, and present vulnerability-aware duplication algorithms to maximize the effectiveness of instruction duplication with least overheads for VLIW architecture. Our experimental results with SoarGen and Synopsys simulation environments demonstrate that our proposals can reduce the code size by up to 40% and detect more soft errors by up to 82% via fault injection experiments over benchmarks from DSPstone and Livermore Loops as compared to the previously proposed instruction duplication technique.
API compilation for image hardware accelerators
Authors: Coelho Fabien , Irigoin François
Published: January 2013

We present an API-based compilation strategy to optimize image applications, developed using a high-level image processing library, onto three different image processing hardware accelerators. We demonstrate that such a strategy is profitable for both development cost and overall performance, especially as it takes advantage of optimization opportunities across library calls otherwise beyond reach. The library API provides the semantics of the image computations. The three image accelerator targets are quite distinct: the first one uses a vector architecture; the second one presents an SIMD architecture; the last one runs both on GPGPU and multicores through OpenCL. We have adapted standard compilation techniques to perform these compilation and code generation tasks automatically. Our strategy is implemented in PIPS, a source-to-source compiler which greatly reduces the development cost as standard phases are reused and parameterized. We carried out experiments with applications on hardware functional simulators and GPUs. Our contributions include: (1) a general low-cost compilation strategy for image processing applications, based on the semantics provided by library calls, which improves locality by an order of magnitude; (2) specific heuristics to minimize execution time on the target accelerators; (3) numerous experiments that show the effectiveness of our strategies. We also discuss the conditions required to extend this approach to other application domains.
Improved loop tiling based on the removal of spurious false dependences
Authors: Baghdadi Riyadh , Cohen Albert , Verdoolaege Sven , Trifunović Konrad
Published: January 2013

To preserve the validity of loop nest transformations and parallelization, data dependences need to be analyzed. Memory dependences come in two varieties: true dependences or false dependences. While true dependences must be satisfied in order to preserve the correct order of computations, false dependences are induced by the reuse of a single memory location to store multiple values. False dependences reduce the degrees of freedom for loop transformations. In particular, loop tiling is severely limited in the presence of these dependences. While array expansion removes all false dependences, the overhead on memory and the detrimental impact on register-level reuse can be catastrophic.

We propose and evaluate a compilation technique to safely ignore a large number of false dependences in order to enable loop nest tiling in the polyhedral model. It is based on the precise characterization of interferences between live range intervals, and it does not incur any scalar or array expansion. Our algorithms have been implemented in the Pluto polyhedral compiler, and evaluated on the PolyBench suite.
Stream arbitration
Authors: Xiao Chunhua , Frank Chang M-C. , Cong Jason , Gill Michael , Huang Zhangqin , Liu Chunyue , Reinman Glenn , Wu Hao
Published: January 2013

Alternative interconnects are attractive for scaling on-chip communication bandwidth in a power-efficient manner. However, efficient utilization of the bandwidth provided by these emerging interconnects still remains an open problem due to the spatial and temporal communication heterogeneity. In this article, a
Stream Arbitration
scheme is proposed, where at runtime any source can compete for any communication channel of the interconnect to talk to any destination. We apply stream arbitration to radio frequency interconnect (RF-I). Experimental results show that compared to the representative token arbitration scheme, stream arbitration can provide an average 20% performance improvement and 12% power reduction.
A repository for CAD examples
Authors: Wilson David J. , Bradford Russell J. , Davenport James H.
Published: January 2013

Cylindrical Algebraic Decomposition (CAD, first introduced in [Col75]) of Euclidean space has become an important tool in mathematics and allows for practical quantifier elimination (QE) over the reals. Much research has gone into improving the projection operator (e.g. [McC85]), the use of partial CADs (e.g. [CH91]), or into alternative algorithms (e.g. [CDM+09]).

A problem of fundamentally high complexity (doubly-exponential in the number of variables [DH88]) it can be difficult to judge when a problem will be solved quickly, and easy to write down problems that are computationally infeasible. It can therefore be difficult to test new advances in this field, and even harder to 'experiment' with new ideas.

We have created a unified machine-readable repository of examples to be used when considering CADs. This allows for quick access to a host of examples, pulled from various theoretical questions and applications. As well as enabling more efficient research, the creation of the repository has prompted us to look deeper at certain questions related to CADs. The example bank currently facilitates quick input for Maple and Qepcad implementations of CAD and QE. Whilst CAD and QE procedures exist in other software, they are not directly involved in our research.
On the complexity of computing the GCD of two polynomials via Hankel matrices
Authors: Belhaj Skander , Kahla Haïthem Ben
Published: January 2013

This paper is devoted to present a revised algorithm that permits to preserve the beautiful relation between the classical Euclidean algorithm and the block diagonalization of Hankel matrices for two noncoprime polynomials. Our algorithm for Greatest Common Divisor (GCD) computation which has a cost of
O
(

n
2

) arithmetic operations is tested for several sets of polynomials. A complexity comparison is given with respect to other existing methods based on structured matrix computations.
Testers
Authors: Bshouty Nader H.
Published: January 2013

We develop a new notion called tester of a class of multivariate polynomials
M
⊆F[χ
1
,..., χ
n
] that maps the elements
a
ε
A
of an F-algebra
A
to a finite number (the size of the tester) of elements
b
1
, . . . ,
b
t
in a smaller sub-algebra
B
⊂
A
where the property
f
(
a
) ≠
0
is preserved for all
f
ε
M
. I.e., for all
f
ε
M
and
a
ε
A
if
f
(
a
) ≠
0
then
f
(
b
i
) ≠
0
for some
i
.

We use tools from elementary algebra and algebraic function fields to construct testers of almost optimal size in deterministic polynomial time in the size of the tester. We then apply testers to deterministically construct new set of objects with some combinatorial and algebraic properties that can be used to derandomize some algorithms.

We show that those new constructions are almost optimal and for many of them meet the union bound of the problem. Constructions include, d-restriction problems, perfect hash, universal sets, cover-free families, separating hash functions, polynomial restriction problems, black box polynomial identity testing for polynomials and circuits over small fields and hitting sets.
Solving non-linear arithmetic
Authors: Jovanović Dejan , de Moura Leonardo
Published: January 2013

We propose a new decision procedure for the existential theory of the reals. It performs a backtracking search for a model in R, where the backtracking is powered by a novel conflict resolution procedure based on cylindrical algebraic decomposition. The initial experimental results are very encouraging. The full article has been accepted at the 6th International Joint Conference on Automated Reasoning (IJCAR 2012).
Sparse differential resultant for laurent differential polynomials
Authors: Li Wei , Yuan Chun-Ming , Gao Xiao-Shan
Published: January 2013

In this poster, we first introduce the concept of Laurent differentially essential systems and give a criterion for them in terms of their supports. Then the sparse differential resultant for a Laurent differentially essential system is defined and its basic properties are given. In particular, order and degree bounds for the sparse differential resultant, as well as a BKK-type degree bound for the differential resultant, are given. Based on these bounds, an algorithm to compute the sparse differential resultant is proposed, which is single exponential.
Polynomial root-finding via structured matrices
Authors: Ugalde Esteban Segura
Published: January 2013

We study the problem of approximating the zeros of an univariate polynomial (up to machine precision). Some popular iterative root-finding methods construct companion matrices (Frobenius, Lagrange) associated with the given polynomial and use eigensolvers to find the eigenvalues of such matrices. Our goal is to study this root-finding technique, exploiting the structure (e.g., diagonal plus rank one) of companion matrices to obtain a decrease of computational cost and memory requirements.
Series misdemeanors
Authors: Stoutemyer David R.
Published: January 2013

Puiseux series are power series in which the exponents can be fractional and/or negative rational numbers. Several computer algebra systems have one or more built-in or loadable functions for computing truncated Puiseux series -- perhaps generalized to allow coefficients containing functions of the series variable that are dominated by any power of that variable, such as logarithms and nested logarithms of the series variable. Some computer-algebra systems also offer functions that can compute more-general truncated recursive hierarchical series. However, for all of these kinds of truncated series there are important implementation details that haven't been addressed before in the published literature and in current implementations.

For implementers this article contains ideas for designing more convenient, correct, and efficient implementations or improving existing ones. For users, this article is a warning about some of these limitations. More specifically, this article discusses issues such as

avoiding unnecessary restrictions such as prohibiting negative or fractional requested orders,

the pros and cons of displaying results with explicit infectious error terms of the form
o
(...),
O
(...), and/or θ(...),

efficient data structures, and

algorithms that efficiently give users exactly the order or number of nonzero terms they request.

.

Most of the ideas in this article have been implemented in the computer-algebra within the TI-Nspire calculator, Windows and Macintosh products.
ISOLDE
Authors: Barkatou Moulay A. , Pflügel Eckhard , Stan Flavia
Published: January 2013

The Maple ISOLDE package contains algorithms for symbolically solving various classes of linear functional systems. In this demonstration, we focus on the local analysis of systems of linear differential and difference equations. We illustrate the use of our formal reduction algorithm and sketch the link with the computation of a formal fundamental matrix solution at a regular or irregular singularity.
A probabilistic approach to mining geospatial knowledge from social annotations
Authors: Intagorn Suradej , Lerman Kristina
Published: January 2013

Knowledge produced online often comes in the form of free-text labels, known as tags, with which users annotate the content they create, such as photos and videos. Increasingly, such content is also georeferenced, i.e., it is associated with geographic coordinates. The implicit relationships between tags and their locations can tell us much about how people conceptualize places and relations between them. However, extracting such knowledge from social annotations presents many challenges, since annotations are often ambiguous, noisy, uncertain and spatially inhomogeneous. We introduce a probabilistic framework for modeling georeferenced annotations and a method for learning model parameters from data. The framework is flexible and general, and can be used in a variety of applications that mine geospatial knowledge from user generated content. Specifically, we study two problems --- extracting place semantics and predicting locations of photos from tags --- and show that performance of our method is comparable to that of state-of-the-art approaches. Moreover, we show that combining the two problems leads to a better performance on the location prediction task than baseline.
Mining multi-object spatial-temporal movement patterns
Authors: Aung Htoo Htet , Tan Kian-Lee
Published: January 2013

In this paper, we present an ongoing PhD research on mining
M
ulti-object
S
patial-
t
emporal
M
ovement Patterns (M-STEM Patterns) from a
T
rajectory
D
ata
b
ase (TJDB). Information of the M-STEM Pattern instances has numerous applications in epidemiology, ecology, location-based services, transportation, and social and behaviour sciences since it supplements the information provided by a traditional GIS. We describe the research we had conducted to find instances of two M-STEM Patterns, namely the Meeting pattern and the Convoy pattern. We conclude this paper after introducing our ongoing research on discovering instances of another M-STEM pattern called Tried-and-True Route pattern.
7 Student Myths of the Online Classroom
Authors: Macek Jo
Published: January 2013

Students have misconceptions of online college course. This article discusses the top seven common myths, and presents remedies for instructors to resolve these inventions. The focus is on specific resolutions of student issues before they become student problems.
An overview of the deco system
Authors: Park Hyunjung , Pang Richard , Parameswaran Aditya , Garcia-Molina Hector , Polyzotis Neoklis , Widom Jennifer
Published: January 2013

Deco is a comprehensive system for answering declarative queries posed over stored relational data together with data obtained on-demand from the crowd. In this overview paper, we describe Deco's data model, query language, and system prototype, summarizing material from earlier papers. Deco's data model was designed to be general, flexible, and principled. Deco's query language extends SQL with simple constructs necessary for crowdsourcing, and has a precise semantics for arbitrary queries. Deco's query execution engine and cost-based query optimizer incorporate many novel techniques to address the limitations of traditional query processing techniques in the crowdsourcing setting. Query processing is guided by the objective of minimizing monetary cost and reducing latency.
Report from the first workshop on scalable workflow enactment engines and technology (SWEET'12)
Authors: Hidders Jan , Sroka Jacek , Missier Paolo
Published: January 2013

This report summarizes the presentations and discussions of SWEET 2012, the First InternationalWorkshop on ScalableWorkflow Enactment Engines and Technologies. SWEET was held in conjunction with the 2012 SIGMOD conference in Scottsdale, Arizona, USA on May 20th, 2012. The goal of the workshop was to bring together researchers and practitioners to explore the state of the art in workflow-based programming for data-intensive applications, and the potential of cloud-based computing in this area. The program featured two very well attended invited talks by Pawel Garbacki from Google and Jimmy Lin from the University of Maryland, on leave at Twitter at the time, as well as a tutorial on Oozie, Yahoo's workflow engine based on
Hadoop
, by Mohammad Islam from Yahoo/Cloudera.
Guiding parallel array fusion with indexed types
Authors: Lippmeier Ben , Chakravarty Manuel , Keller Gabriele , Peyton Jones Simon
Published: January 2013

We present a refined approach to parallel array fusion that uses indexed types to specify the internal representation of each array. Our approach aids the client programmer in reasoning about the performance of their program in terms of the source code. It also makes the intermediate code easier to transform at compile-time, resulting in faster compilation and more reliable runtimes. We demonstrate how our new approach improves both the clarity and performance of several end-user written programs, including a fluid flow solver and an interpolator for volumetric data.
Vectorisation avoidance
Authors: Keller Gabriele , Chakravarty Manuel M.T. , Leshchinskiy Roman , Lippmeier Ben , Peyton Jones Simon
Published: January 2013

Flattening nested parallelism is a vectorising code transform that converts irregular nested parallelism into flat data parallelism. Although the result has good asymptotic performance, flattening thoroughly restructures the code. Many intermediate data structures and traversals are introduced, which may or may not be eliminated by subsequent optimisation. We present a novel program analysis to identify parts of the program where flattening would only introduce overhead, without appropriate gain. We present empirical evidence that avoiding vectorisation in these cases leads to more efficient programs than if we had applied vectorisation and then relied on array fusion to eliminate intermediates from the resulting code.
Testing type class laws
Authors: Jeuring Johan , Jansson Patrik , Amaral Cláudio
Published: January 2013

The specification of a class in Haskell often starts with stating, in comments, the laws that should be satisfied by methods defined in instances of the class, followed by the type of the methods of the class. This paper develops a framework that supports testing such class laws using QuickCheck. Our framework is a light-weight class law testing framework, which requires a limited amount of work per class law, and per datatype for which the class law is tested. We also show how to test class laws with partially-defined values. Using partially-defined values, we show that the standard lazy and strict implementations of the state monad do not satisfy the expected laws.