bluuebunny/crossref_metadata_2025_split huggingface dataset:
Real-time smoke rendering using compensated ray marching
Authors: Zhou Kun , Ren Zhong , Lin Stephen , Bao Hujun , Guo Baining , Shum Heung-Yeung 
Published: August 2008

We present a real-time algorithm calledcompensated ray marchingfor rendering of smoke under dynamic low-frequency environment lighting. Our approach is based on a decomposition of the input smoke animation, represented as a sequence of volumetric density fields, into a set of radial basis functions (RBFs) and a sequence of residual fields. To expedite rendering, the source radiance distribution within the smoke is computed from only the low-frequency RBF approximation of the density fields, since the high-frequency residuals have little impact on global illumination under low-frequency environment lighting. Furthermore, in computing source radiances the contributions from single and multiple scattering are evaluated at only the RBF centers and then approximated at other points in the volume using an RBF-based interpolation. A slice-based integration of these source radiances along each view ray is then performed to render the final image. The high-frequency residual fields, which are a critical component in the local appearance of smoke, are compensated back into the radiance integral during this ray march to generate images of high detail.The runtime algorithm, which includes both light transfer simulation and ray marching, can be easily implemented on the GPU, and thus allows for real-time manipulation of viewpoint and lighting, as well as interactive editing of smoke attributes such as extinction cross section, scattering albedo, and phase function. Only moderate preprocessing time and storage is needed. This approach provides the first method for real-time smoke rendering that includes single and multiple scattering while generating results comparable in quality to offline algorithms like ray tracing.
Markerless garment capture
Authors: Bradley Derek , Popa Tiberiu , Sheffer Alla , Heidrich Wolfgang , Boubekeur Tamy 
Published: August 2008

A lot of research has recently focused on the problem of capturing the geometry and motion of garments. Such work usually relies on special markers printed on the fabric to establish temporally coherent correspondences between points on the garment's surface at different times. Unfortunately, this approach is tedious and prevents the capture of off-the-shelf clothing made from interesting fabrics.
In this paper, we describe a marker-free approach to capturing garment motion that avoids these downsides. We establish temporally coherent parameterizations between incomplete geometries that we extract at each timestep with a multiview stereo algorithm. We then fill holes in the geometry using a template. This approach, for the first time, allows us to capture the geometry and motion of unpatterned, off-the-shelf garments made from a range of different fabrics.
Interview with David Harris, MTV New Media
Authors: Lee Newton , Harris David 
Published: August 2008

David Harris was born in Puerto Rico, raised in Texas, and received his undergraduate degree in Film, Animation, and Video from the Rhode Island School of Design. He worked as the creative director for Love Advertising, producer for ADV Films, Inc. (one of America's leading animé companies), and lived in Paris for a year in between. In 2003, he relocated to Los Angeles to pursue his MFA from UCLA in Film, TV and Digital Media. His thesis project, HOWDOISAYTHIS.COM, was sponsored by mtvU and Cisco and won the 2007 SXSW Web Award for Best Student Site. Since launching HOWDOISAYTHIS.COM, Harris worked in the development think tank at Fox Television Studios before taking his current position at MTV New Media, where he is working on the Players project, Jackass World, and a number of interactive projects that are as exciting as they are secret. In the video interview, you will hear David's answers to the following questions:
1. You call yourself the "MacGyver" at MTV New Media. Could you elaborate on your role at MTV?
2. How does MTV New Media compete with MySpace and YouTube in reaching the MTV audience on the Internet?
3. What is your experience in working with the AFI Digital Content Lab?
4. What suggestions do you have that would make the Digital Content Lab more innovative, useful, and rewarding?
5. What is the innovation of the "Players" project that you are working on at the Digital Content Lab?
6. If you can do anything you want at MTV, what will you do?
Relations as an abstraction for BDD-based program analysis
Authors: Lhoták Ondřej , Hendren Laurie 
Published: August 2008

In this article we present Jedd, a language extension to Java that supports a convenient way of programming with Binary Decision Diagrams (BDDs). The Jedd language abstracts BDDs as database-style relations and operations on relations, and provides static type rules to ensure that relational operations are used correctly.
The article provides a description of the Jedd language and reports on the design and implementation of the Jedd translator and associated runtime system. Of particular interest is the approach to assigning attributes from the high-level relations to physical domains in the underlying BDDs, which is done by expressing the constraints as a SAT problem and using a modern SAT solver to compute the solution. Further, a runtime system is defined that handles memory management issues and supports a browsable profiling tool for tuning the key BDD operations.
The motivation for designing Jedd was to support the development of interrelated whole program analyses based on BDDs. We have successfully used Jedd to build Paddle, a framework of context-sensitive program analyses, including points-to analysis and call graph construction, as well as several client analyses.
Matching algorithmic bounds for finding a Brouwer fixed point
Authors: Chen Xi , Deng Xiaotie 
Published: August 2008

We prove a new discrete fixed point theorem for direction-preserving functions defined on integer points, based on a novel characterization of boundary conditions for the existence of fixed points. The theorem allows us to derive an improved algorithm for finding such a fixed point. We also develop a new lower bound proof technique. Together, they allow us to derive an asymptotic matching bound for the problem of finding a fixed point in a hypercube of any constantly bounded finite dimension.
Exploring a linkage with the approximation version of the continuous fixed point problem, we obtain asymptotic matching bounds for the complexity of the approximate Brouwer fixed point problem in the continuous case for Lipschitz functions. It settles a fifteen-years-old open problem of Hirsch, Papadimitriou, and Vavasis by improving both the upper and lower bounds.
Our characterization for the existence of a fixed point is also applicable to functions defined on nonconvex domains, which makes it a potentially useful tool for the design and analysis of algorithms for fixed points in general domains.
Computing correlated equilibria in multi-player games
Authors: Papadimitriou Christos H. , Roughgarden Tim 
Published: August 2008

We develop polynomial-time algorithms for finding correlated equilibria—a well-studied notion of rationality that generalizes the Nash equilibrium—in a broad class of succinctly representable multiplayer games, encompassing graphical games, anonymous games, polymatrix games, congestion games, scheduling games, local effect games, as well as several generalizations. Our algorithm is based on a variant of the existence proof due to Hart and Schmeidler, and employs linear programming duality, the ellipsoid algorithm, Markov chain steady state computations, as well as application-specific methods for computing multivariate expectations over product distributions.
For anonymous games and graphical games of bounded tree-width, we provide a different polynomial-time algorithm for optimizing an arbitrary linear function over the set of correlated equilibria of the game. In contrast to our sweeping positive results for computing an arbitrary correlated equilibrium, we prove that optimizing over correlated equilibria is NP-hard in all of the other classes of games that we consider.
Online auctions and generalized secretary problems
Authors: Babaioff Moshe , Immorlica Nicole , Kempe David , Kleinberg Robert 
Published: August 2008

We present generalized secretary problems as a framework for online auctions. Elements, such as potential employees or customers, arrive one by one online. After observing the value derived from an element, but without knowing the values of future elements, the algorithm has to make an irrevocable decision whether to retain the element as part of a solution, or reject it. The way in which the secretary framework differs from traditional online algorithms is that the elements arrive in uniformly random order.
Many natural online auction scenarios can be cast as generalized secretary problems, by imposing natural restrictions on the feasible sets. For many such settings, we present surprisingly strong constant factor guarantees on the expected value of solutions obtained by online algorithms. The framework is also easily augmented to take into account time-discounted revenue and incentive compatibility. We give an overview of recent results and future research directions.
A lightweight streaming layer for multicore execution
Authors: Zhang David , Li Qiuyuan J. , Rabbah Rodric , Amarasinghe Saman 
Published: August 2008

As multicore architectures gain widespread use, it becomes increasingly important to be able to harness their additional processing power to achieve higher performance. However, exploiting parallel cores to improve single-program performance is difficult from a programmer's perspective because most existing programming languages dictate a sequential method of execution.
Stream programming, which organizes programs by independent filters communicating over explicit data channels, exposes useful types of parallelism that can be exploited. However, there is still the burden of mapping high-level stream programs to specific multicore architectures. The complexities of each architecture's underlying details makes it difficult to schedule the execution of a stream program with high performance.
In this paper, we present the specifications for an intermediate layer between the stream program and the target architecture. This multicore streaming layer (MSL) provides a common level of abstraction that facilitates efficient execution of stream programs by making it easier for compilers to manage computation, and by providing automatic orchestration and optimization of communication when appropriate. We implemented a framework for one such instance of the MSL targeted to the Cell processor and the StreamIt language and achieved greater than 88% utilization on all benchmarks with relatively small amounts of code. The framework can also be applied to other architectures and stream programming languages to enhance generality and portability.
Southern Hemisphere Winter Extratropical Cyclone Characteristics and Vertical Organization Observed with the ERA-40 Data in 1979–2001
Authors: Lim Eun-Pa , Simmonds Ian 
Published: August 2008

Abstract
The mean characteristics and trends of Southern Hemisphere (SH) winter extratropical cyclones occurring at six levels of the troposphere over the period 1979–2001 have been investigated using the 40-yr ECMWF Re-Analysis (ERA-40) data. Cyclonic systems were identified with the Melbourne University cyclone finding and tracking scheme.
This study shows that mean sea level pressure (MSLP) cyclones are more numerous, more intense, smaller, deeper, and slower moving than higher-level cyclones. The novel vertical tracing scheme devised for this research revealed that about 52% of SH winter MSLP cyclones have a vertically well organized structure, extending through to the 500-hPa level. About 80% of these vertically coherent SH cyclones keep their westward tilt until the surface cyclones reach their maximum depths, and the mean distance is 300 km between the surface and the 500-hPa level cyclone centers when the surface cyclones obtain their maturity. According to the authors’ definition of vertical organization, explosively developing cyclones are vertically very well organized systems, whose surface development is antecedent to their 500-hPa level counterpart.
Over 1979–2001 cyclones have increased in their system density, intensity, and translational velocity but decreased in their scale at almost all levels. However, some of the trends are not statistically significant. The proportion of vertically well organized systems in the entire population of SH winter extratropical cyclones has considerably increased over the last 23 yr, and the mean distance between the surface and the 500-hPa- level cyclone centers has decreased. Such changes in vertical organization of extratropical cyclones are statistically significant at the 95% confidence level.
A Java-based tool for the design of classification microarrays
Authors: Meng Da , Broschat Shira L , Call Douglas R 
Published: August 2008

Abstract

Background
Classification microarrays are used for purposes such as identifying strains of bacteria and determining genetic relationships to understand the epidemiology of an infectious disease. For these cases, mixed microarrays, which are composed of DNA from more than one organism, are more effective than conventional microarrays composed of DNA from a single organism. Selection of probes is a key factor in designing successful mixed microarrays because redundant sequences are inefficient and limited representation of diversity can restrict application of the microarray. We have developed a Java-based software tool, called PLASMID, for use in selecting the minimum set of probe sequences needed to classify different groups of plasmids or bacteria.

Results
The software program was successfully applied to several different sets of data. The utility of PLASMID was illustrated using existing mixed-plasmid microarray data as well as data from a virtual mixed-genome microarray constructed from different strains of Streptococcus. Moreover, use of data from expression microarray experiments demonstrated the generality of PLASMID.

Conclusion
In this paper we describe a new software tool for selecting a set of probes for a classification microarray. While the tool was developed for the design of mixed microarrays–and mixed-plasmid microarrays in particular–it can also be used to design expression arrays. The user can choose from several clustering methods (including hierarchical, non-hierarchical, and a model-based genetic algorithm), several probe ranking methods, and several different display methods. A novel approach is used for probe redundancy reduction, and probe selection is accomplished via stepwise discriminant analysis. Data can be entered in different formats (including Excel and comma-delimited text), and dendrogram, heat map, and scatter plot images can be saved in several different formats (including jpeg and tiff). Weights generated using stepwise discriminant analysis can be stored for analysis of subsequent experimental data. Additionally, PLASMID can be used to construct virtual microarrays with genomes from public databases, which can then be used to identify an optimal set of probes.
Dynamic expression of Dab2 in the mouse embryonic central nervous system
Authors: Cheung Kwok-Kuen , Mok Samuel C , Rezaie Payam , Chan Wood Yee 
Published: August 2008

AbstractBackgroundDab2, one of two mammalian orthologs ofDrosophila Disabled, has been shown to be involved in cell positioning and formation of visceral endoderm during mouse embryogenesis, but its role in neuronal development is not yet fully understood. In this report, we have examined the localization of the Dab2 protein in the mouse embryonic central nervous system (CNS) at different developmental stages.ResultsDab2 protein was transiently expressed in rhombomeres 5 and 6 of the developing hindbrain between E8.5 and E11.5, and in the floor plate of the neural tube from E9.5 to E12.5, following which it was no longer detectable within these regions. Dab2 protein was also identified within circumventricular organs including the choroid plexus, subcommissural organ and pineal gland during their early development. While Dab2 was still strongly expressed in the adult choroid plexus, immunoreactivity within the subcommissural organ and pineal gland was lost after birth. In addition, Dab2 was transiently expressed within a subpopulation of Iba1-positive mononuclear phagocytes (including presumed microglial progenitors) within the neural tube from E10.0 and was lost by E14.5. Dab2 was separately localized to Iba1 positive cells from E9.5 and subsequently to F4/80 positive cells (mature macrophage/myeloid-derived dendritic cells) positioned outside the neural tube from E12.5 onwards, implicating Dab2 expression in early cells of the mononuclear phagocyte lineage. Dab2 did not co-localize with the pan-neuronal marker PGP9.5 at any developmental stage, suggesting that Dab2 positive cells in the developing CNS are unlikely to be differentiating neurons.ConclusionThis is the first study to demonstrate the dynamic spatiotemporal expression of Dab2 protein within the CNS during development.
Regional differences in HIV prevalence among drug users in China: potential for future spread of HIV?
Authors: Kretzschmar Mirjam , Zhang Weidong , Mikolajczyk Rafael T , Wang Lan , Sun Xinhua , Kraemer Alexander , Lv Fan 
Published: August 2008

Abstract

Background
Drug use and in particular injecting drug use has been at the forefront of the explosive spread of HIV in general populations in many countries in Asia. There is concern that also in China increased HIV incidence in drug users might spark off a generalized epidemic in the wider population. Close monitoring of HIV incidence and risk factors in drug users is therefore important to be able to target interventions effectively. Second generation surveillance was launched to assess HIV prevalence and risk behaviours jointly with the purpose of describing trends and predicting future developments. To assess whether these goals were fulfilled among drug users in China we provide an analysis of risk factors for HIV infection and of regional differences in HIV prevalence.

Methods
We analysed data collected in 2005 in 21 drug user second generation surveillance sentinel sites from 14 provinces in China. We used random effects logistic regression to test for risk factors for HIV infection and regional differences.

Results
The overall HIV-1 antibody prevalence was 5.4% (279/5128); 4.9% among injecting drug users (IDU) not sharing needles and 3.7% among non-injecting drug users. We found substantial heterogeneity among the surveillance sites with prevalence rates ranging between 0% and 54%. HIV status was strongly affected by the regional prevalence of HIV. Risk behaviours were highly prevalent in regions where HIV prevalence is still low. The distribution of duration of drug use in different sites indicated different stages of the drug use epidemics.

Conclusion
]Regional differences in HIV prevalence in China reflect different stages of the drug use and HIV epidemics rather than differences in risk behaviours. Therefore, outbreaks of HIV among drug users in regions where prevalence is still low can be expected in the future. However, methodological limitations of surveillance embedded into routine systems limit the usability of existing data. More standardized approaches to data collection in secondary generation HIV surveillance are necessary to better understand regional differences in risk behaviour and prevalence and to design targeted intervention for those regions at risk of experiencing outbreaks.
Melasma and its association with different types of nevi in women: A case-control study
Authors: Adalatkhah Hassan , Sadeghi-bazargani Homayoun , Amini-sani Nayereh , Zeynizadeh Somayeh 
Published: August 2008

Abstract

Background
Very little is known about possible association of nevi and melasma. The study objective was to determine if there is an association between melasma and existence of different kinds of nevi.

Methods
In a case-control study, 120 female melasma patients referred to dermatology clinic of Ardabil and 120 patients referred to other specialty clinics who lacked melasma were enrolled after matching for age. Number of different types of nevi including lentigines and melanocytic nevi were compared between case and control group patients. Data were entered into the computer and analyzed by SPSS 13 statistical software.

Results
Mean number of lentigines was 25.5 in melasma group compared to 8 in control group(P < 0.01). Mean number of melanocytic nevi was 13.2 in cases compared to 2.8 in control group(P < 0.001). Multivariate analysis showed that existence of freckles, lentigines and more than three melanocytic nevi were positively related to developing melasma. The chance of melasma increased up to 23 times for patients having more than three melanocytic nevi. Congenital nevi were observed among 10% both in case and control groups. Campbell de morgan angiomas were seen among 26 patients(21.8%) in case group compared to 6 patients(5%) in control group.

Conclusion
Existence of lentigines and melanocytic nevi increases chance of having melasma
Level set segmentation of bovine corpora lutea in ex situ ovarian ultrasound images
Authors: Rusnell Brennan J , Pierson Roger A , Singh Jaswant , Adams Gregg P , Eramian Mark G 
Published: August 2008

Abstract

Background
The objective of this study was to investigate the viability of level set image segmentation methods for the detection of corpora lutea (corpus luteum, CL) boundaries in ultrasonographic ovarian images. It was hypothesized that bovine CL boundaries could be located within 1–2 mm by a level set image segmentation methodology.

Methods
Level set methods embed a 2D contour in a 3D surface and evolve that surface over time according to an image-dependent speed function. A speed function suitable for segmentation of CL's in ovarian ultrasound images was developed. An initial contour was manually placed and contour evolution was allowed to proceed until the rate of change of the area was sufficiently small. The method was tested on ovarian ultrasonographic images (n = 8) obtained ex situ. A expert in ovarian ultrasound interpretation delineated CL boundaries manually to serve as a "ground truth". Accuracy of the level set segmentation algorithm was determined by comparing semi-automatically determined contours with ground truth contours using the mean absolute difference (MAD), root mean squared difference (RMSD), Hausdorff distance (HD), sensitivity, and specificity metrics.

Results and discussion
The mean MAD was 0.87 mm (sigma = 0.36 mm), RMSD was 1.1 mm (sigma = 0.47 mm), and HD was 3.4 mm (sigma = 2.0 mm) indicating that, on average, boundaries were accurate within 1–2 mm, however, deviations in excess of 3 mm from the ground truth were observed indicating under- or over-expansion of the contour. Mean sensitivity and specificity were 0.814 (sigma = 0.171) and 0.990 (sigma = 0.00786), respectively, indicating that CLs were consistently undersegmented but rarely did the contour interior include pixels that were judged by the human expert not to be part of the CL. It was observed that in localities where gradient magnitudes within the CL were strong due to high contrast speckle, contour expansion stopped too early.

Conclusion
The hypothesis that level set segmentation can be accurate to within 1–2 mm on average was supported, although there can be some greater deviation. The method was robust to boundary leakage as evidenced by the high specificity. It was concluded that the technique is promising and that a suitable data set of human ovarian images should be obtained to conduct further studies.