bluuebunny/crossref_metadata_2025 huggingface dataset:
Bacteremia Caused by Extended-Spectrum-β-Lactamase-Producing Escherichia coli Sequence Type ST131 and Non-ST131 Clones: Comparison of Demographic Data, Clinical Features, and Mortality
Authors: Chung Hsing-Chun , Lai Chung-Hsu , Lin Jiun-Nong , Huang Chun-Kai , Liang Shiou-Haur , Chen Wei-Fang , Shih Yi-Chun , Lin Hsi-Hsun , Wang Jiun-Ling
Published: November 2011

Escherichia coli
producing the highly virulent, multidrug-resistant, CTX-M-15 extended-spectrum β-lactamase (ESBL), sequence type 131 (ST131), has emerged on three continents since the late 2000s. We described the molecular epidemiology, clinical features, and outcome of ESBL-producing
E. coli
bacteremia in Taiwan from 2005 to 2010. This study aims to determine whether the risk factors, clinical features, and outcomes of the ST131 isolate differ from those of non-ST131 isolates. From 2005 to 2010, we collected 122 nonduplicated, consecutive, ESBL-producing
E. coli
isolates from bloodstream infections in a 1,200-bed hospital in Taiwan. Isolates were characterized using multilocus sequence typing. Demographic data, clinical features, and outcomes were collected from medical chart records. Thirty-six (29.5%) patients with bacteremia with ESBL-producing
E. coli
ST131 were identified. Patients with clone ST131 were more likely to have secondary bacteremia and noncatheterized urinary tract infections (
P
< 0.05). Secondary bacteremia (odds ratio [OR], 5.05; 95% confidence interval [CI], 1.08 to 23.56) and urinary catheter nonuse (OR, 3.77; 95% CI, 1.17 to 12.18) were independent risk factors for the ST131 clone after adjustment. Mortality rates at day 28 were similar in ST131 and non-ST131 populations. Independent risk factors predicting mortality at day 28 included malignancy, shock, and hospital-acquired bacteremia. In ESBL-producing
E. coli
bloodstream infections, the ST131 clone was not associated with health-care-associated risk factors, such as urinary catheter use or antibiotic exposure. Although highly virulent and multidrug resistant, the ST131 clone was not associated with higher mortality than non-ST131 clones.
In Vitro
Resistance Profile of the Candidate HIV-1 Microbicide Drug Dapivirine
Authors: Schader Susan M. , Oliveira Maureen , Ibanescu Ruxandra-Ilinca , Moisi Daniela , Colby-Germinario Susan P. , Wainberg Mark A.
Published: November 2011

Antiretroviral-based microbicides may offer a means to reduce the sexual transmission of HIV-1. Suboptimal use of a microbicide may, however, lead to the development of drug resistance in users that are already, or become, infected with HIV-1. In such cases, the efficacy of treatments may be compromised since the same (or similar) antiretrovirals used in treatments are being developed as microbicides. To help predict which drug resistance mutations may develop in the context of suboptimal use, HIV-1 primary isolates of different subtypes and different baseline resistance profiles were used to infect primary cells
in vitro
in the presence of increasing suboptimal concentrations of the two candidate microbicide antiretrovirals dapivirine (DAP) and tenofovir (TFV) alone or in combination. Infections were ongoing for 25 weeks, after which reverse transcriptase genotypes were determined and scrutinized for the presence of any clinically recognized reverse transcriptase drug resistance mutations. Results indicated that suboptimal concentrations of DAP alone facilitated the emergence of common nonnucleoside reverse transcriptase inhibitor resistance mutations, while suboptimal concentrations of DAP plus TFV gave rise to fewer mutations. Suboptimal concentrations of TFV alone did not frequently result in the development of resistance mutations. Sensitivity evaluations for stavudine (d4T), nevirapine (NVP), and lamivudine (3TC) revealed that the selection of resistance as a consequence of suboptimal concentrations of DAP may compromise the potential for NVP to be used in treatment, a finding of potential relevance in developing countries.
Reproductive phenology of the Caribbean cactus Harrisia portoricensis: rainfall and temperature associations
Authors: Rojas-Sandoval Julissa , Meléndez-Ackerman Elvia
Published: November 2011

Phenological patterns often influence the extent of reproductive success of plants as well the interaction among species. In this study, we evaluated the association of local climatic factors and plant size with the reproductive phenology of the threatened cactus Harrisia portoricensis in the Caribbean dry forest of Mona Island. Analyses of phenological data gathered monthly in 572 plants over 2 years concluded that for this species, reproductive activity is continuous throughout the year and reproductive output is positively correlated with plant size. Bud production in H. portoricensis was positively associated with temporal changes in monthly mean and minimum temperatures, while flower production was positively associated with total monthly rainfall. When compared with other columnar cacti species, the combined phenological responses to temperature and rainfall in H. portoricensis represent a different strategy. We hypothesize that contrasting phenological responses among columnar cacti may stem from site-specific differences in the degree of intra-annual rainfall or temperature variability. If that is the case, then monitoring reproductive responses of cacti to expected changes in climate at a global scale would require gathering phenological data for this taxon across different geographic regions.
VIBRATION MODEL AND ANALYSIS OF THREE-MEMBER TELESCOPIC BOOM WITH HYDRAULIC CYLINDER FOR ITS RADIUS CHANGE
Authors: CEKUS DAWID , POSIADALA BOGDAN
Published: November 2011

In this paper, the free vibration problem of a system consisting of a three-member type telescopic boom of the laboratory crane, the hydraulic cylinder of crane radius change and the elastic support system has been presented. The model has been formulated in order to represent the vibrations in the lifting plane of the laboratory crane. The transverse vibrations of the boom, longitudinal and transverse vibrations of the hydraulic cylinder have been considered in the coupled model of the system taking into account the elasticity of the support system. In the computational model, the analyzed system has been replaced by the discrete-continuous model. The free vibration problem of the analyzed system is formulated and solved on the basis of Lagrange multiplier formalism. The experimental modal analysis is done and the genetic algorithm worked out with the aim of identifying spring constants of the support system elements. The analysis of the influence of the hydraulic cylinder and the length of the telescopic boom on the free vibration frequencies is carried out on the basis of the identified vibration model of the considered system. The examples of the experimental and numerical results are presented.
SPATIAL RELATIONSHIPS BETWEEN SURFACE RUPTURES IN THE Ms 8.0 WENCHUAN EARTHQUAKE, THE LONGMEN SHAN REGION, SICHUAN, CHINA
Authors: LI YONG , ZHOU RONGJUN , DENSMORE ALEXANDER L. , CAO SHUYOU , LIU YUPING
Published: November 2011

During the M s 8.0 Wenchuan Earthquake of May 12, 2008, three distinct faults in the Longmen Shan along the eastern margin of the Tibetan Plateau ruptured. We have carried out detailed field geological mapping on these faults (the Yingxiu-Beichuan, the Pengxian-Guanxian, and the Xiaoyudong Faults), as well as the minor Leigu Fault, using GPS and total station surveys. The surface rupture of the Wenchuan Earthquake consists of two margin-parallel thrust faults linked by the Xiaoyudong tear fault. By comparing the features of the surface rupture of the faults, the spatial relationships between the different surface ruptures can be determined. It is clear that the margin-parallel thrust faults are linked at depth, forming an imbricated thrust linked by a tear fault.
SURGE GENERATION IN RESERVOIRS BY LANDSLIDES TRIGGERED BY THE WENCHUAN EARTHQUAKE
Authors: CUI PENG , ZHU XINGHUA
Published: November 2011

Landslides can result in rocks and soil falling into reservoir at high velocity, thereby triggering large surface waves, which may threaten navigation vessels, dam stability, and lives and properties along the shore. This paper presents the results of an experimental study into surges caused by landslides entering reservoirs. First, eight factors — water depth, sliding impact velocity, slide volume, slide width, slide thickness, the mass of the slide blocks, sliding slope, and drop height of the mass center — were chosen as key parameters. Then, these were combined into four dimensionless factors: Froude number for sliding velocity, landslide scale, slide thickness and slide impact angle (radian measure). In addition, based on data from 145 model tests, empirical equations for prediction of the first and second impulsive wave heights were developed through nondimensional multiple linear regression analysis. These equations were applied to landslides triggered by the Wenchuan Earthquake along the shore of Zipingpu Reservoir. The calculated results were found to be in good agreement with field surveys and with calculations by other formulas; the proposed formula is believed preferable in that it incorporates dimension parameters and slope of the sliding surface.
IMPACT OF EARTHQUAKE ON DEBRIS FLOWS — A CASE STUDY ON THE WENCHUAN EARTHQUAKE
Authors: CHEN NING-SHENG , HU GUI-SHENG , DENG MING-FENG , ZHOU WEI , YANG CHENG-LIN , HAN D. , DENG JIAN-HUI
Published: November 2011

This paper describes a study about the impact of earthquakes on debris flows with a focus on the Great Wenchuan Earthquake 2008 in China. The land form, precipitation, and source material are the three key factors for debris flow initiation in the Wenchuan surrounding area. Classifications and examples of four types of debris flow initiation triggering (gully triggering, slope triggering, liquefaction triggering, and gully erosion triggering) have been presented. The initiation mechanisms are attributed to hydraulic and geomechanical aspects. The actual debris flow cases linked with the Great Wenchuan Earthquake and other earthquakes in China have been used to illustrate the increased magnitudes of debris flows due to a large amount of loose materials created by the seismic actions. The critical precipitation for debris flows is reduced by the earthquake. It is predicted that the impact of the Great Wenchuan Earthquake on the local debris flows would be significant in the next 5–6 years, and much less in the following years (up to 20 years). Finally, the debris flow system will reach a relative stable stage. This prediction is based on the historical observations at other earthquake areas and the qualitative analysis on debris flow initiation mechanisms.
Surface morphology characteristics of rock discontinuities with particular reference to their genesis
Authors: Aydan Ömer , Shimizu Yasuhiro
Published: November 2011

A research program was undertaken to characterize the surface morphology of natural discontinuities with particular reference to their genesis. For this purpose a special profilometer, which could easily be transported and operated in the field, and was capable of measuring 480 mm long profiles, was designed. The recorded profiles were digitized and analysed to obtain surface morphology characteristics of the discontinuities in different rock types found in Central Japan. Natural discontinuities have an anisotropic surface topography which may be characterized by measuring profiles along their eigen directions. Consequently, surface morphology parameters are directional and differ depending upon the discontinuity type.
Observations on fractography with laboratory experiments for geologists
Authors: Kulander B. R. , Dean Stuart L.
Published: November 2011

Brittle fracture growth proceeds through unique stages, each marked by distinct fractographic features that can only develop during Mode I loading at the propagating crack tip. Fractographic features in any substance can be interpreted in terms of the location of the failure origin, as well as changes in propagation velocities, stress directions and stress magnitudes at the crack tip during failure. Joints in granular pervious rock, however, do not contain fractographic features, commonly formed in glass, that develop at unstable propagation rates under the influence of appreciable amounts of stored strain energy. Yet, features that develop at lower stable rates of propagation are present on fractures in glass and rock implying that the absence of certain fractographic features provides useful information.

Simple laboratory experiments, primarily on glass, are discussed to provide geologists an opportunity to recognize and qualitatively interpret fractographic features diagnostic of brittle failure. The exercises demonstrate the changing propagation dynamics that control the morphological evolution of artificially-induced fractures and natural joints in rock.
The expression of hydraulic fracturing in rocks and sediments
Authors: Cosgrove J. W.
Published: November 2011

The orientation and spatial organization of hydraulic fractures in rocks and sediments is determined by the magnitude of the differential stress, the orientation of the principal stress axes and the intrinsic properties of the rock, particularly its cohesive strength. Depending on the values of these various parameters the expression of hydraulic fracturing in a rock or sediment can be extremely varied ranging from conjugate shear fractures through parallel tension fractures to randomly oriented tension fractures and fluidized sediments.

The influence of a rock’s properties on its response to hydraulic fracturing is illustrated by considering the mechanics of formation of sedimentary dykes.
Demand Paging Techniques for Flash Memory Using Compiler Post-Pass Optimizations
Authors: Kim Seungkyun , Kwon Kiwon , Kim Chihun , Jang Choonki , Lee Jaejin , Min Sang Lyul
Published: November 2011

In this article, we propose an application-specific demand paging mechanism for low-end embedded systems that have flash memory as secondary storage. These systems are not equipped with virtual memory. A small memory space called an execution buffer is used to page the code of an application. An application-specific page manager manages the buffer. The page manager is automatically generated by a compiler post-pass optimizer and combined with the application image. The post-pass optimizer analyzes the executable image and transforms function call/return instructions into calls to the page manager. As a result, each function in the code can be loaded into the memory on demand at runtime. To minimize the overhead incurred by the demand paging technique, code clustering algorithms are also presented. We evaluate our techniques with ten embedded applications, and our approach can reduce the code memory size by on average 39.5% with less than 10% performance degradation and on average 14% more energy consumption. Our demand paging technique provides embedded system designers with a trade-off control mechanism between the cost, performance, and energy efficiency in designing embedded systems. Embedded system designers can choose the code memory size depending on their cost, energy, and performance requirements.
A Hardware Abstraction Layer in Java
Authors: Schoeberl Martin , Korsholm Stephan , Kalibera Tomas , Ravn Anders P.
Published: November 2011

Embedded systems use specialized hardware devices to interact with their environment, and since they have to be dependable, it is attractive to use a modern, type-safe programming language like Java to develop programs for them. Standard Java, as a platform-independent language, delegates access to devices, direct memory access, and interrupt handling to some underlying operating system or kernel, but in the embedded systems domain resources are scarce and a Java Virtual Machine (JVM) without an underlying middleware is an attractive architecture. The contribution of this article is a proposal for Java packages with hardware objects and interrupt handlers that interface to such a JVM. We provide implementations of the proposal directly in hardware, as extensions of standard interpreters, and finally with an operating system middleware. The latter solution is mainly seen as a migration path allowing Java programs to coexist with legacy system components. An important aspect of the proposal is that it is compatible with the Real-Time Specification for Java (RTSJ).
Compiler-Supported Thread Management for Multithreaded Network Processors
Authors: Zhuang Xiaotong , Pande Santosh
Published: November 2011

Traditionally, runtime management involving CPU sharing, real-time scheduling, etc., is provided by the runtime environment (typically an operating system) using hardware support such as timers and interrupts. However, due to stringent performance requirements on network processors, neither OS nor hardware mechanisms are typically feasible/available. Mapping packet processing tasks on network processors involves complex trade-offs to maximize parallelism and pipelining. Due to an increase in the size of the code store and complexity of application requirements, network processors are being programmed with heterogeneous threads that may execute code belonging to different tasks on a given micro-engine. Also, most network applications are streaming applications that are typically processed in a pipelined fashion. Thus, the tasks on different micro-engines are pipelined in such a way as to maximize the throughput. Tasks themselves could have different runtime performance demands.

In this article, we focus on network processors on which hardware can only schedule threads in a round-robin fashion and no OS assistance is provided. We show that it is very difficult and inefficient for the programmer to meet the constraints of runtime management by coding them statically. Due to the infeasibility of hardware or OS solution (even in the near future), we undertake a compiler approach.

We propose a complete compiler solution to automatically insert explicit context switch (ctx) instructions provided on the network processor such that the execution of threads is better manipulated at runtime to meet their constraints. Two approaches are presented that can control programs’ runtime behavior with different applicability and overheads. We show that it is feasible and also opens new application domains that would need heterogeneous thread programming. Such approaches would in general become important for multicore processors.

Finally, our experiments show that the runtime constraints are enforced nearly ideally with minimal runtime degradation and small code growth.
The ReNoC Reconfigurable Network-on-Chip
Authors: Stuart Matthias Bo , Stensgaard Mikkel Bystrup , Sparsø Jens
Published: November 2011

This article presents a reconfigurable network-on-chip architecture called ReNoC, which is intended for use in general-purpose multiprocessor system-on-chip platforms, and which enables application-specific logical NoC topologies to be configured, thus providing both efficiency and flexibility. The article presents three novel algorithms that synthesize an application-specific NoC topology, map it onto the physical ReNoC architecture, and create deadlock-free, application-specific routing algorithms. We apply our algorithms to a mixture of real and synthetic applications and target three different physical architectures. Compared to a conventional NoC, ReNoC reduces power consumption by up to 58% on average.
A Robust Mechanism for Adaptive Scheduling of Multimedia Applications
Authors: Cucinotta Tommaso , Abeni Luca , Palopoli Luigi , Lipari Giuseppe
Published: November 2011

We propose an adaptive scheduling technique to schedule highly dynamic multimedia tasks on a CPU. We use a combination of two techniques: the first one is a feedback mechanism to track the resource requirements of the tasks based on “local” observations. The second one is a mechanism that operates with a “global” visibility, reclaiming unused bandwidth. The combination proves very effective: resource reclaiming increases the robustness of the feedback, while the identification of the correct bandwidth made by the feedback increases the effectiveness of the reclamation. We offer both theoretical results and an extensive experimental validation of the approach.
Joint shape segmentation with linear programming
Authors: Huang Qixing , Koltun Vladlen , Guibas Leonidas
Published: November 2011

We present an approach to segmenting shapes in a heterogenous shape database. Our approach segments the shapes jointly, utilizing features from multiple shapes to improve the segmentation of each. The approach is entirely unsupervised and is based on an integer quadratic programming formulation of the joint segmentation problem. The program optimizes over possible segmentations of individual shapes as well as over possible correspondences between segments from multiple shapes. The integer quadratic program is solved via a linear programming relaxation, using a block coordinate descent procedure that makes the optimization feasible for large databases. We evaluate the presented approach on the Princeton segmentation benchmark and show that joint shape segmentation significantly outperforms single-shape segmentation techniques.
Unsupervised co-segmentation of a set of shapes via descriptor-space spectral clustering
Authors: Sidi Oana , van Kaick Oliver , Kleiman Yanir , Zhang Hao , Cohen-Or Daniel
Published: November 2011

We introduce an algorithm for unsupervised co-segmentation of a set of shapes so as to reveal the semantic shape parts and establish their correspondence across the set. The input set may exhibit significant shape variability where the shapes do not admit proper spatial alignment and the corresponding parts in any pair of shapes may be geometrically dissimilar. Our algorithm can handle such challenging input sets since, first, we perform co-analysis in a
descriptor space
, where a combination of shape descriptors relates the parts independently of their pose, location, and cardinality. Secondly, we exploit a key enabling feature of the input set, namely, dissimilar parts may be "linked" through third-parties present in the set. The links are derived from the pairwise similarities between the parts' descriptors. To reveal such linkages, which may manifest themselves as anisotropic and non-linear structures in the descriptor space, we perform spectral clustering with the aid of diffusion maps. We show that with our approach, we are able to co-segment sets of shapes that possess significant variability, achieving results that are close to those of a supervised approach.
Multiview face capture using polarized spherical gradient illumination
Authors: Ghosh Abhijeet , Fyffe Graham , Tunwattanapong Borom , Busch Jay , Yu Xueming , Debevec Paul
Published: November 2011

We present a novel process for acquiring detailed facial geometry with high resolution diffuse and specular photometric information from multiple viewpoints using polarized spherical gradient illumination. Key to our method is a new pair of linearly polarized lighting patterns which enables
multiview
diffuse-specular separation under a given spherical illumination condition from just two photographs. The patterns -- one following lines of latitude and one following lines of longitude -- allow the use of fixed linear polarizers in front of the cameras, enabling more efficient acquisition of diffuse and specular albedo and normal maps from multiple viewpoints. In a second step, we employ these albedo and normal maps as input to a novel multi-resolution adaptive domain message passing stereo reconstruction algorithm to create high resolution facial geometry. To do this, we formulate the stereo reconstruction from multiple cameras in a commonly parameterized domain for multiview reconstruction. We show competitive results consisting of high-resolution facial geometry with relightable reflectance maps using five DSLR cameras. Our technique scales well for multiview acquisition without requiring specialized camera systems for sensing multiple polarization states.
General planar quadrilateral mesh design using conjugate direction field
Authors: Liu Yang , Xu Weiwei , Wang Jun , Zhu Lifeng , Guo Baining , Chen Falai , Wang Guoping
Published: November 2011

We present a novel method to approximate a freeform shape with a planar quadrilateral (PQ) mesh for modeling architectural glass structures. Our method is based on the study of conjugate direction fields (CDF) which allow the presence of ±κ/4(κ ε Z) singularities. Starting with a triangle discretization of a freeform shape, we first compute an as smooth as possible conjugate direction field satisfying the user's directional and angular constraints, then apply mixed-integer quadrangulation and planarization techniques to generate a PQ mesh which approximates the input shape faithfully. We demonstrate that our method is effective and robust on various 3D models.
Connectivity editing for quadrilateral meshes
Authors: Peng Chi-Han , Zhang Eugene , Kobayashi Yoshihiro , Wonka Peter
Published: November 2011

We propose new connectivity editing operations for quadrilateral meshes with the unique ability to explicitly control the location, orientation, type, and number of the irregular vertices (valence not equal to four) in the mesh while preserving sharp edges. We provide theoretical analysis on what editing operations are possible and impossible and introduce three
fundamental
operations to move and re-orient a pair of irregular vertices. We argue that our editing operations are fundamental, because they only change the quad mesh in the smallest possible region and involve the fewest irregular vertices (i.e., two). The irregular vertex movement operations are supplemented by operations for the splitting, merging, canceling, and aligning of irregular vertices. We explain how the proposed high-level operations are realized through graph-level editing operations such as quad collapses, edge flips, and edge splits. The utility of these mesh editing operations are demonstrated by improving the connectivity of quad meshes generated from state-of-art quadrangulation techniques.
Material matting
Authors: Lepage Daniel , Lawrence Jason
Published: November 2011

Despite the widespread use of measured real-world materials, intuitive tools for editing measured reflectance datasets are still lacking. We present a solution inspired by natural image matting and texture synthesis to thematerial mattingproblem, which allows separating a measured spatially-varying material into simpler foreground and background component materials and a corresponding opacity map. We approach this problem in the context of Bayesian statistics and introduce a new prior on materials that favors those with highly self-similar stochastic structure. We describe a prototype system that iteratively performs these separations based on small sets of user scribbles and demonstrate multiple separations and edits.
Fusion of depth maps with multiple scales
Authors: Fuhrmann Simon , Goesele Michael
Published: November 2011

Multi-view stereo systems can produce depth maps with large variations in viewing parameters, yielding vastly different sampling rates of the observed surface. We present a new method for surface reconstruction by integrating a set of registered depth maps with dramatically varying sampling rate. The method is based on the construction of a hierarchical signed distance field represented in an incomplete primal octree by incrementally adding triangulated depth maps. Due to the adaptive data structure, our algorithm is able to handle depth maps with varying scale and to consistently represent coarse, low-resolution regions as well as small details contained in high-resolution depth maps. A final surface mesh is extracted from the distance field by construction of a tetrahedral complex from the scattered signed distance values and applying the Marching Tetra-hedra algorithm on the partition. The output is an adaptive triangle mesh that seamlessly connects coarse and highly detailed regions while avoiding filling areas without suitable input data.
Genetic programming for shader simplification
Authors: Sitthi-Amorn Pitchaya , Modly Nicholas , Weimer Westley , Lawrence Jason
Published: November 2011

We present a framework based on Genetic Programming (GP) for automatically simplifying procedural shaders. Our approach computes a series of increasingly simplified shaders that expose the inherent trade-off between speed and accuracy. Compared to existing automatic methods for pixel shader simplification [Olano et al. 2003; Pellacini 2005], our approach considers a wider space of code transformations and produces faster and more faithful results. We further demonstrate how our cost function can be rapidly evaluated using graphics hardware, which allows tens of thousands of shader variants to be considered during the optimization process. Our approach is also applicable to multi-pass shaders and perceptual-based error metrics.
Data-driven visual similarity for cross-domain image matching
Authors: Shrivastava Abhinav , Malisiewicz Tomasz , Gupta Abhinav , Efros Alexei A.
Published: November 2011

The goal of this work is to find
visually similar
images even if they appear quite different at the raw pixel level. This task is particularly important for matching images across visual domains, such as photos taken over different seasons or lighting conditions, paintings, hand-drawn sketches, etc. We propose a surprisingly simple method that estimates the relative importance of different features in a query image based on the notion of "data-driven uniqueness". We employ standard tools from discriminative object detection in a novel way, yielding a generic approach that does not depend on a particular image representation or a specific visual domain. Our approach shows good performance on a number of difficult cross-domain visual tasks e.g., matching paintings or sketches to real photographs. The method also allows us to demonstrate novel applications such as
Internet re-photography
, and painting2gps. While at present the technique is too computationally intensive to be practical for interactive image retrieval, we hope that some of the ideas will eventually become applicable to that domain as well.
Semantic colorization with internet images
Authors: Chia Alex Yong-Sang , Zhuo Shaojie , Gupta Raj Kumar , Tai Yu-Wing , Cho Siu-Yeung , Tan Ping , Lin Stephen
Published: November 2011

Colorization of a grayscale photograph often requires considerable effort from the user, either by placing numerous color scribbles over the image to initialize a color propagation algorithm, or by looking for a suitable reference image from which color information can be transferred. Even with this user supplied data, colorized images may appear unnatural as a result of limited user skill or inaccurate transfer of colors. To address these problems, we propose a colorization system that leverages the rich image content on the internet. As input, the user needs only to provide a semantic text label and segmentation cues for major foreground objects in the scene. With this information, images are downloaded from photo sharing websites and filtered to obtain suitable reference images that are reliable for color transfer to the given grayscale photo. Different image colorizations are generated from the various reference images, and a graphical user interface is provided to easily select the desired result. Our experiments and user study demonstrate the greater effectiveness of this system in comparison to previous techniques.
Adaptive sampling and reconstruction using greedy error minimization
Authors: Rousselle Fabrice , Knaus Claude , Zwicker Matthias
Published: November 2011

We introduce a novel approach for image space adaptive sampling and reconstruction in Monte Carlo rendering. We greedily minimize relative mean squared error (MSE) by iterating over two steps. First, given a current sample distribution, we optimize over a discrete set of filters at each pixel and select the filter that minimizes the pixel error. Next, given the current filter selection, we distribute additional samples to further reduce MSE. The success of our approach hinges on a robust technique to select suitable per pixel filters. We develop a novel filter selection procedure that robustly solves this problem even with noisy input data. We evaluate our approach using effects such as motion blur, depth of field, interreflections, etc. We provide a comparison to a state-of-the-art algorithm based on wavelet shrinkage and show that we achieve significant improvements in numerical error and visual image quality. Our approach is simple to implement, requires a single user parameter, and is compatible with standard Monte Carlo rendering.
Coherent parallel hashing
Authors: García Ismael , Lefebvre Sylvain , Hornus Samuel , Lasram Anass
Published: November 2011

Recent spatial hashing schemes hash millions of keys in parallel, compacting sparse spatial data in small hash tables while still allowing for fast access from the GPU. Unfortunately, available schemes suffer from two drawbacks: Multiple runs of the construction process are often required before success, and the random nature of the hash functions decreases access performance.

We introduce a new parallel hashing scheme which reaches high load factor with a very low failure rate. In addition our scheme has the unique advantage to exploit coherence in the data and the access patterns for faster performance. Compared to existing approaches, it exhibits much greater locality of memory accesses and consistent execution paths within groups of threads. This is especially well suited to Computer Graphics applications, where spatial coherence is common. In absence of coherence our scheme performs similarly to previous methods, but does not suffer from construction failures.

Our scheme is based on the Robin Hood scheme modified to quickly abort queries of keys that are not in the table, and to preserve coherence. We demonstrate our scheme on a variety of data sets. We analyze construction and access performance, as well as cache and threads behavior.
Stretchable and Twistable Bones for Skeletal Shape Deformation
Authors: Jacobson Alec , Sorkine Olga
Published: November 2011

Skeleton-based linear blend skinning (LBS) remains the most popular method for real-time character deformation and animation. The key to its success is its simple implementation and fast execution. However, in addition to the well-studied elbow-collapse and candy-wrapper artifacts, the space of deformations possible with LBS is inherently limited. In particular, blending with only a scalar weight function per bone prohibits properly handling stretching, where bones change length, and twisting, where the shape rotates along the length of the bone. We present a simple modification of the LBS formulation that enables stretching and twisting without changing the existing skeleton rig or bone weights. Our method needs only an extra scalar weight function per bone, which can be painted manually or computed automatically. The resulting formulation significantly enriches the space of possible deformations while only increasing storage and computation costs by constant factors.
Slices
Authors: McCrae James , Singh Karan , Mitra Niloy J.
Published: November 2011

Minimalist object representations or
shape-proxies
that spark and inspire human perception of shape remain an incompletely understood, yet powerful aspect of visual communication. We explore the use of planar sections, i.e., the contours of intersection of planes with a 3D object, for creating shape abstractions, motivated by their popularity in art and engineering. We first perform a user study to show that humans do define consistent and similar planar section proxies for common objects. Interestingly, we observe a strong correlation between user-defined planes and geometric features of objects. Further we show that the problem of finding the minimum set of planes that capture a set of 3D geometric shape features is both NP-hard and not always the proxy a user would pick. Guided by the principles inferred from our user study, we present an algorithm that progressively selects planes to maximize feature coverage, which in turn influence the selection of subsequent planes. The algorithmic framework easily incorporates various shape features, while their relative importance values are computed and validated from the user study data. We use our algorithm to compute planar slices for various objects, validate their utility towards object abstraction using a second user study, and conclude showing the potential applications of the extracted planar slice shape proxies.
Practical spectral characterization of trichromatic cameras
Authors: Rump Martin , Zinke Arno , Klein Reinhard
Published: November 2011

Simple and effective geometric and radiometric calibration of camera devices has enabled the use of consumer digital cameras for HDR photography, for image based measurement and similar applications requiring a deeper understanding about the camera characteristics. However, to date no such practical methods for estimating the spectral response of cameras are available. Existing approaches require costly hardware and controlled acquisition conditions limiting their applicability. Consequently, even though being highly desirable for color correction and color processing purposes as well as for designing image-based measurement or photographic setups, the spectral response of a camera is rarely considered. Our objective is to close this gap. In this work a practical approach for multi-spectral characterization of trichromatic cameras is presented. Taking photographs of a color chart and measuring the average lighting using a spectrophotometer the effective spectral response of a camera can be estimated for a wide range of out-of-lab environments. By comprehensive cross validation experiments we prove that the new method performs well compared to costly reference measurements. Moreover, we show that our technique can also be used to generate ICC profiles with higher accuracy and less constrained capturing conditions compared to state-of-the-art ICC profilers.
Multigrid and multilevel preconditioners for computational photography
Authors: Krishnan Dilip , Szeliski Richard
Published: November 2011

This paper unifies multigrid and multilevel (hierarchical) preconditioners, two widely-used approaches for solving computational photography and other computer graphics simulation problems. It provides detailed experimental comparisons of these techniques and their variants, including an analysis of relative computational costs and how these impact practical algorithm performance. We derive both theoretical convergence rates based on the condition numbers of the systems and their preconditioners, and empirical convergence rates drawn from real-world problems. We also develop new techniques for sparsifying higher connectivity problems, and compare our techniques to existing and newly developed variants such as algebraic and combinatorial multigrid. Our experimental results demonstrate that, except for highly irregular problems, adaptive hierarchical basis function preconditioners generally outperform alternative multigrid techniques, especially when computational complexity is taken into account.
Adaptive partitioning of urban facades
Authors: Shen Chao-Hui , Huang Shi-Sheng , Fu Hongbo , Hu Shi-Min
Published: November 2011

Automatically discovering high-level facade structures in unorganized 3D point clouds of urban scenes is crucial for applications like digitalization of real cities. However, this problem is challenging due to poor-quality input data, contaminated with severe missing areas, noise and outliers. This work introduces the concept of
adaptive partitioning
to automatically derive a flexible and hierarchical representation of 3D urban facades. Our key observation is that urban facades are largely governed by concatenated and/or interlaced grids. Hence, unlike previous automatic facade analysis works which are typically restricted to globally rectilinear grids, we propose to automatically partition the facade in an adaptive manner, in which the splitting direction, the number and location of splitting planes are all adaptively determined. Such an adaptive partition operation is performed recursively to generate a hierarchical representation of the facade. We show that the concept of adaptive partitioning is also applicable to flexible and robust analysis of image facades. We evaluate our method on a dozen of LiDAR scans of various complexity and styles, and the image facades from the eTRIMS database and the Ecole Centrale Paris database. A series of applications that benefit from our approach are also demonstrated.
Does Varicocelectomy Improve Gonadal Function in Men with Hypogonadism and Infertility? Analysis of a Prospective Study
Authors: Sathya Srini Vasan , Belur Veerachari Srinivas
Published: November 2011

Varicocele in infertile males is associated with Leydig cell dysfunction and hypogonadism. The effect of varicocelectomy on serum testosterone level is not yet established. We analysed 200 heterosexual infertile men diagnosed to have clinical varicocele they were divided into two groups: group 1 (100 men) had microsurgical varicocelectomy, and group 2 (100 patients) underwent assisted reproduction procedures. All participants had semen analysis, serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin, and total testosterone (TT), measured both at recruitment time and 6 months later. In group 1, the mean TT level increased significantly after varicocelectomy (1.644±0.029to2.461±0.0198 ng/dL,P<0.0001) and testicular size correlated with the mean change in TT (P=0.001). No similar change was found in group 2. Out of the 100 patients in group 1, 78 had postoperative normalization of TT unlike only 16 men in group 2.
Cornual Polyps of the Fallopian Tube Are Associated with Endometriosis and Anovulation
Authors: AlAsiri S. A. , Ghahremani M. , McComb P. F.
Published: November 2011

Background. The relationship between tubal cornual polyps and endometriosis and ovulatory disorders in infertile women is unclear. Our objective was to determine such an association from our database and review the literature.Methods. Twenty-two infertile women with tubal cornual polyps were assessed for coexistence of oligoovulation/anovulation and endometriosis with stratification for polyp diameter (large: ≥5 mm diameter, small <5 mm diameter).Result(s). Oligoovulation/anovulation was more prevalent in women with large versus small tubal cornual polyps (P=0.0048). Endometriosis was associated with both large and small polyps.Conclusion(s). This case series confirms the association of tubal cornual polyps with oligoovulation/anovulation and endometriosis in infertile women. This case series is limited by a lack of controls.
Dangers and pleasures: Drug attitudes and experiences among young people
Authors: Järvinen Margaretha , Østergaard Jeanette
Published: November 2011

This is a study of young people’s conceptions of illegal drug use as dangerous and/or pleasurable and an analysis of the relationship between attitudes to drugs, drinking, friends’ reported drug use and own experience with drug use and drinking. The article applies a mixed methods approach using both survey data and focus group interviews. The main statistical method is Multiple Correspondence Analysis (MCA), which constructs a social space of young people’s attitudes to drugs and drug experiences relationally. We identify four interrelated positions on illegal drug use among 17 to 19-year-old Danes: the anti-drug position, usually held by youths who do not use illegal drugs and do not have drug-using friends; the ambivalent position, occupied by non-users who report that they have drug-using friends; the transitory position, held by cannabis users, some of whom express positive attitudes to ‘hard’ illegal drugs; and, finally, the pro-drug position, characteristic of drug users with low risk perceptions and high pleasure-orientation. We use the focus group interviews to demonstrate how youths occupying these differing positions argue for and against drugs and which risks and pleasures they associate with drug use.
Validation of Automated Scoring of Oral Reading
Authors: Balogh Jennifer , Bernstein Jared , Cheng Jian , Van Moere Alistair , Townshend Brent , Suzuki Masanori
Published: November 2011

A two-part experiment is presented that validates a new measurement tool for scoring oral reading ability. Data collected by the U.S. government in a large-scale literacy assessment of adults were analyzed by a system called VersaReader that uses automatic speech recognition and speech processing technologies to score oral reading fluency. In the first part of the experiment, human raters rated oral reading performances to establish a criterion measure for comparisons with the machine scores. The goal was to measure the reliability of ratings from human raters and to determine whether or not the human raters biased their ratings in favor of or against three groups of readers: Spanish speakers, African Americans, and all other native English speakers. The result of the experiment showed that ratings from skilled human raters were extremely reliable. In addition, there was no observed scoring bias for human raters. The second part of the experiment was designed to compare the criterion human ratings with scores generated by VersaReader. Correlations between VersaReader scores and human ratings approached unity. Using G-Theory, the results showed that machine scores were almost identical to scores from human raters. Finally, the results revealed no bias in the machine scores. Implications for large-scale assessments are discussed.
Naga militancy and violent politics in the shadow of ceasefire
Authors: Kolås Åshild
Published: November 2011

Ceasefires are often seen as a simple measure to end violence and allow more substantive negotiations to begin. Contemporary conflict resolution models thus posit the ceasefire as a basic step in the peacebuilding trajectory. Offering an in-depth analysis of Naga militancy in Northeast India, this article argues that ceasefires should rather be understood as a part of the dynamics of conflict. Northeast India is a site of protracted conflict involving multiple contestants, where Naga militant organizations play a key role. A string of ceasefires since 1997 between the Indian government and the National Socialist Council of Nagalim (NSCN) has contained fighting between security forces and militants, while violence has continued unabated between NSCN factions and among an array of other armed groups in the area claimed as ‘Nagalim’, with serious consequences for local communities. This study suggests that ceasefires may impact on conflict dynamics in at least three ways, all interrelated: (1) by affecting the internal cohesion of belligerent groups, (2) by affecting the operational space of armed groups, and (3) by affecting the relations between multiple stakeholders and parties to a conflict, including but not limited to the challenger(s) and the state. The study concludes that the terms of ceasefire agreements, the strategic use of ceasefires by conflict actors, and the opportunities created by a lack of effective monitoring of ceasefire ground rules has facilitated the operations of militants vying for territory, revenues from illegal ‘taxation’ and political stakes. Ceasefires have also paved the way for an escalation of factional and intergroup fighting and violent politics in Northeast India, by empowering signatory groups versus contenders as well as nonviolent actors.