bluuebunny/crossref_metadata_2025 huggingface dataset:
Foveated 3D graphics
Authors: Guenter Brian , Finch Mark , Drucker Steven , Tan Desney , Snyder John
Published: November 2012

We exploit the falloff of acuity in the visual periphery to accelerate graphics computation by a factor of 5-6 on a desktop HD display (1920x1080). Our method tracks the user's gaze point and renders three image layers around it at progressively higher angular size but lower sampling rate. The three layers are then magnified to display resolution and smoothly composited. We develop a general and efficient antialiasing algorithm easily retrofitted into existing graphics code to minimize "twinkling" artifacts in the lower-resolution layers. A standard psychophysical model for acuity falloff assumes that minimum detectable angular size increases linearly as a function of eccentricity. Given the slope characterizing this falloff, we automatically compute layer sizes and sampling rates. The result looks like a full-resolution image but reduces the number of pixels shaded by a factor of 10-15.

We performed a user study to validate these results. It identifies two levels of foveation quality: a more conservative one in which users reported foveated rendering quality as equivalent to or better than non-foveated when directly shown both, and a more aggressive one in which users were unable to correctly label as increasing or decreasing a short quality progression relative to a high-quality foveated reference. Based on this user study, we obtain a slope value for the model of 1.32-1.65 arc minutes per degree of eccentricity. This allows us to predict two future advantages of foveated rendering: (1) bigger savings with larger, sharper displays than exist currently (e.g. 100 times speedup at a field of view of 70° and resolution matching foveal acuity), and (2) a roughly linear (rather than quadratic or worse) increase in rendering cost with increasing display field of view, for planar displays at a constant sharpness.
Co-abstraction of shape collections
Authors: Yumer Mehmet Ersin , Kara Levent Burak
Published: November 2012

We present a co-abstraction method that takes as input a collection of 3D objects, and produces a mutually consistent and individually identity-preserving abstraction of each object. In general, an abstraction is a simpler version of a shape that preserves its main characteristics. We hypothesize, however, that there is no single abstraction of an object. Instead, there is a variety of possible abstractions, and an admissible one can only be chosen conjointly with other objects' abstractions. To this end, we introduce a new approach that hierarchically generates a spectrum of abstractions for each model in a shape collection. Given the spectra, we compute the appropriate abstraction level for each model such that shape simplification and inter-set consistency are collectively maximized, while individual shape identities are preserved.
An optimization approach for extracting and encoding consistent maps in a shape collection
Authors: Huang Qi-Xing , Zhang Guo-Xin , Gao Lin , Hu Shi-Min , Butscher Adrian , Guibas Leonidas
Published: November 2012

We introduce a novel approach for computing high quality point-to-point maps among a collection of related shapes. The proposed approach takes as input a sparse set of imperfect initial maps between pairs of shapes and builds a compact data structure which implicitly encodes an improved set of maps between all pairs of shapes. These maps align well with point correspondences selected from initial maps; they map neighboring points to neighboring points; and they provide cycle-consistency, so that map compositions along cycles approximate the identity map.

The proposed approach is motivated by the fact that a complete set of maps between all pairs of shapes that admits nearly perfect cycle-consistency are highly redundant and can be represented by compositions of maps through a single base shape. In general, multiple base shapes are needed to adequately cover a diverse collection. Our algorithm sequentially extracts such a small collection of base shapes and creates correspondences from each of these base shapes to all other shapes. These correspondences are found by global optimization on candidate correspondences obtained by diffusing initial maps. These are then used to create a compact graphical data structure from which globally optimal cycle-consistent maps can be extracted using simple graph algorithms.

Experimental results on benchmark datasets show that the proposed approach yields significantly better results than state-of-the-art data-driven shape matching methods.
Inverse design of urban procedural models
Authors: Vanegas Carlos A. , Garcia-Dorado Ignacio , Aliaga Daniel G. , Benes Bedrich , Waddell Paul
Published: November 2012

We propose a framework that enables adding intuitive high level control to an existing urban procedural model. In particular, we provide a mechanism to interactively edit urban models, a task which is important to stakeholders in gaming, urban planning, mapping, and navigation services. Procedural modeling allows a quick creation of large complex 3D models, but controlling the output is a well-known open problem. Thus, while forward procedural modeling has thrived, in this paper we add to the arsenal an inverse modeling tool. Users, unaware of the rules of the underlying urban procedural model, can alternatively specify arbitrary target indicators to control the modeling process. The system itself will discover how to alter the parameters of the urban procedural model so as to produce the desired 3D output. We label this process inverse design.
Analysis and synthesis of point distributions based on pair correlation
Authors: Öztireli A. Cengiz , Gross Markus
Published: November 2012

Analyzing and synthesizing point distributions are of central importance for a wide range of problems in computer graphics. Existing synthesis algorithms can only generate white or blue-noise distributions with characteristics dictated by the underlying processes used, and analysis tools have not been focused on exploring relations among distributions. We propose a unified analysis and general synthesis algorithms for point distributions. We employ the pair correlation function as the basis of our methods and design synthesis algorithms that can generate distributions with given target characteristics, possibly extracted from an example point set, and introduce a unified characterization of distributions by mapping them to a space implied by pair correlations. The algorithms accept example and output point sets of different sizes and dimensions, are applicable to multi-class distributions and non-Euclidean domains, simple to implement and run in
O
(
n
) time. We illustrate applications of our method to real world distributions.
Blue noise through optimal transport
Authors: de Goes Fernando , Breeden Katherine , Ostromoukhov Victor , Desbrun Mathieu
Published: November 2012

We present a fast, scalable algorithm to generate high-quality blue noise point distributions of arbitrary density functions. At its core is a novel formulation of the recently-introduced concept of capacity-constrained Voronoi tessellation as an optimal transport problem. This insight leads to a continuous formulation able to enforce the capacity constraints exactly, unlike previous work. We exploit the variational nature of this formulation to design an efficient optimization technique of point distributions via constrained minimization in the space of power diagrams. Our mathematical, algorithmic, and practical contributions lead to high-quality blue noise point sets with improved spectral and spatial properties.
Gaze correction for home video conferencing
Authors: Kuster Claudia , Popa Tiberiu , Bazin Jean-Charles , Gotsman Craig , Gross Markus
Published: November 2012

Effective communication using current video conferencing systems is severely hindered by the lack of eye contact caused by the disparity between the locations of the subject and the camera. While this problem has been partially solved for high-end expensive video conferencing systems, it has not been convincingly solved for consumer-level setups. We present a gaze correction approach based on a single Kinect sensor that preserves both the integrity and expressiveness of the face as well as the fidelity of the scene as a whole, producing nearly artifact-free imagery. Our method is suitable for mainstream home video conferencing: it uses inexpensive consumer hardware, achieves real-time performance and requires just a simple and short setup. Our approach is based on the observation that for our application it is sufficient to synthesize only the corrected face. Thus we render a gaze-corrected 3D model of the scene and, with the aid of a face tracker, transfer the gaze-corrected facial portion in a seamless manner onto the original image.
Discontinuity-aware video object cutout
Authors: Zhong Fan , Qin Xueying , Peng Qunsheng , Meng Xiangxu
Published: November 2012

Existing video object cutout systems can only deal with limited cases. They usually require detailed user interactions to segment real-life videos, which often suffer from both inseparable statistics (similar appearance between foreground and background) and temporal discontinuities (e.g. large movements, newly-exposed regions following disocclusion or topology change).

In this paper, we present an efficient video cutout system to meet this challenge. A novel directional classifier is proposed to handle temporal discontinuities robustly, and then multiple classifiers are incorporated to cover a variety of cases. The outputs of these classifiers are integrated via another classifier, which is learnt from real examples. The foreground matte is solved by a coherent matting procedure, and remaining errors can be removed easily by additive spatio-temporal local editing. Experiments demonstrate that our system performs more robustly and more intelligently than existing systems in dealing with various input types, thus saving a lot of user labor and time.
Field-guided registration for feature-conforming shape composition
Authors: Huang Hui , Gong Minglun , Cohen-Or Daniel , Ouyang Yaobin , Tan Fuwen , Zhang Hao
Published: November 2012

We present an automatic shape composition method to fuse two shape parts which may not overlap and possibly contain sharp features, a scenario often encountered when modeling man-made objects. At the core of our method is a novel
field-guided
approach to automatically align two input parts in a
feature-conforming
manner. The key to our field-guided shape registration is a
natural continuation
of one part into the ambient field as a means to introduce an overlap with the distant part, which then allows a surface-to-field registration. The ambient vector field we compute is feature-conforming; it characterizes a piecewise smooth field which respects and naturally extrapolates the surface features. Once the two parts are aligned, gap filling is carried out by spline interpolation between matching feature curves followed by piecewise smooth least-squares surface reconstruction. We apply our algorithm to obtain feature-conforming shape composition on a variety of models and demonstrate generality of the method with results on parts with or without overlap and with or without salient features.
Structure recovery by part assembly
Authors: Shen Chao-Hui , Fu Hongbo , Chen Kang , Hu Shi-Min
Published: November 2012

This paper presents a technique that allows quick conversion of acquired low-quality data from consumer-level scanning devices to high-quality 3D models with labeled semantic parts and meanwhile their assembly reasonably close to the underlying geometry. This is achieved by a novel structure recovery approach that is essentially local to global and bottom up, enabling the creation of new structures by assembling existing labeled parts with respect to the acquired data. We demonstrate that using only a small-scale shape repository, our part assembly approach is able to faithfully recover a variety of high-level structures from only a single-view scan of man-made objects acquired by the Kinect system, containing a highly noisy, incomplete 3D point cloud and a corresponding RGB image.
Multi-scale partial intrinsic symmetry detection
Authors: Xu Kai , Zhang Hao , Jiang Wei , Dyer Ramsay , Cheng Zhiquan , Liu Ligang , Chen Baoquan
Published: November 2012

We present an algorithm for
multi-scale
partial intrinsic symmetry detection over 2D and 3D shapes, where the scale of a symmetric region is defined by intrinsic distances between symmetric points over the region. To identify prominent symmetric regions which overlap and vary in form and scale, we decouple scale extraction and symmetry extraction by performing two levels of clustering. First, significant symmetry scales are identified by clustering sample point
pairs
from an input shape. Since different point pairs can share a common point, shape regions covered by points in different scale clusters can overlap. We introduce the
symmetry scale matrix
(SSM), where each entry estimates the likelihood two point pairs belong to symmetries at the same scale. The
pair-to-pair
symmetry affinity is computed based on a pair signature which encodes scales. We perform spectral clustering using the SSM to obtain the scale clusters. Then for all points belonging to the same scale cluster, we perform the second-level spectral clustering, based on a novel
point-to-point
symmetry affinity measure, to extract partial symmetries at that scale. We demonstrate our algorithm on complex shapes possessing rich symmetries at multiple scales.
Perspective-aware warping for seamless stereoscopic image cloning
Authors: Luo Sheng-Jie , Shen I-Chao , Chen Bing-Yu , Cheng Wen-Huang , Chuang Yung-Yu
Published: November 2012

This paper presents a novel technique for seamless stereoscopic image cloning, which performs both shape adjustment and color blending such that the stereoscopic composite is seamless in both the perceived depth and color appearance. The core of the proposed method is an iterative disparity adaptation process which alternates between two steps: disparity estimation, which re-estimates the disparities in the gradient domain so that the disparities are continuous across the boundary of the cloned region; and perspective-aware warping, which locally re-adjusts the shape and size of the cloned region according to the estimated disparities. This process guarantees not only depth continuity across the boundary but also models local perspective projection in accordance with the disparities, leading to more natural stereoscopic composites. The proposed method allows for easy cloning of objects with intricate silhouettes and vague boundaries because it does not require precise segmentation of the objects. Several challenging cases are demonstrated to show that our method generates more compelling results compared to methods with only global shape adjustment.
Enabling warping on stereoscopic images
Authors: Niu Yuzhen , Feng Wu-Chi , Liu Feng
Published: November 2012

Warping is one of the basic image processing techniques. Directly applying existing monocular image warping techniques to stereoscopic images is problematic as it often introduces vertical disparities and damages the original disparity distribution. In this paper, we show that these problems can be solved by appropriately warping both the disparity map and the two images of a stereoscopic image. We accordingly develop a technique for extending existing image warping algorithms to stereoscopic images. This technique divides stereoscopic image warping into three steps. Our method first applies the user-specified warping to one of the two images. Our method then computes the target disparity map according to the user specified warping. The target disparity map is optimized to preserve the perceived 3D shape of image content after image warping. Our method finally warps the other image using a spatially-varying warping method guided by the target disparity map. Our experiments show that our technique enables existing warping methods to be effectively applied to stereoscopic images, ranging from parametric global warping to non-parametric spatially-varying warping.
Correcting for optical aberrations using multilayer displays
Authors: Huang Fu-Chung , Lanman Douglas , Barsky Brian A. , Raskar Ramesh
Published: November 2012

Optical aberrations of the human eye are currently corrected using eyeglasses, contact lenses, or surgery. We describe a fourth option: modifying the composition of displayed content such that the perceived image appears in focus, after passing through an eye with known optical defects. Prior approaches synthesize pre-filtered images by deconvolving the content by the point spread function of the aberrated eye. Such methods have not led to practical applications, due to severely reduced contrast and ringing artifacts. We address these limitations by introducing multilayer pre-filtering, implemented using stacks of semi-transparent, light-emitting layers. By optimizing the layer positions and the partition of spatial frequencies between layers, contrast is improved and ringing artifacts are eliminated. We assess design constraints for multilayer displays; autostereoscopic light field displays are identified as a preferred, thin form factor architecture, allowing synthetic layers to be displaced in response to viewer movement and refractive errors. We assess the benefits of multilayer pre-filtering versus prior light field pre-distortion methods, showing pre-filtering works within the constraints of current display resolutions. We conclude by analyzing benefits and limitations using a prototype multilayer LCD.
The magic lens
Authors: Papas Marios , Houit Thomas , Nowrouzezahrai Derek , Gross Markus , Jarosz Wojciech
Published: November 2012

We present an automatic approach to design and manufacture passive display devices based on optical hidden image decoding. Motivated by classical steganography techniques we construct
Magic Lenses
, composed of refractive lenslet arrays, to reveal hidden images when placed over potentially unstructured printed or displayed source images. We determine the refractive geometry of these surfaces by formulating and efficiently solving an inverse light transport problem, taking into account additional constraints imposed by the physical manufacturing processes. We fabricate several variants on the basic magic lens idea including using a single source image to encode several hidden images which are only revealed when the lens is placed at prescribed orientations on the source image or viewed from different angles. We also present an important special case, the
universal lens
, that forms an injection mapping from the lens surface to the source image grid, allowing it to be used with arbitrary source images. We use this type of lens to generate hidden animation sequences. We validate our simulation results with many real-world manufactured magic lenses, and experiment with two separate manufacturing processes.
Accurate realtime full-body motion capture using a single depth camera
Authors: Wei Xiaolin , Zhang Peizhao , Chai Jinxiang
Published: November 2012

We present a fast, automatic method for accurately capturing full-body motion data using a single depth camera. At the core of our system lies a realtime registration process that accurately reconstructs 3D human poses from single monocular depth images, even in the case of significant occlusions. The idea is to formulate the registration problem in a
Maximum A Posteriori
(MAP) framework and iteratively register a 3D articulated human body model with monocular depth cues via linear system solvers. We integrate depth data, silhouette information, full-body geometry, temporal pose priors, and occlusion reasoning into a unified MAP estimation framework. Our 3D tracking process, however, requires manual initialization and recovery from failures. We address this challenge by combining 3D tracking with 3D pose detection. This combination not only automates the whole process but also significantly improves the robustness and accuracy of the system. Our whole algorithm is highly parallel and is therefore easily implemented on a GPU. We demonstrate the power of our approach by capturing a wide range of human movements in real time and achieve state-of-the-art accuracy in our comparison against alternative systems such as
Kinect
[2012].
Data-driven finger motion synthesis for gesturing characters
Authors: Jörg Sophie , Hodgins Jessica , Safonova Alla
Published: November 2012

Capturing the body movements of actors to create animations for movies, games, and VR applications has become standard practice, but finger motions are usually added manually as a tedious post-processing step. In this paper, we present a surprisingly simple method to automate this step for gesturing and conversing characters. In a controlled environment, we carefully captured and post-processed finger and body motions from multiple actors. To augment the body motions of virtual characters with plausible and detailed finger movements, our method selects finger motion segments from the resulting database taking into account the similarity of the arm motions and the smoothness of consecutive finger motions. We investigate which parts of the arm motion best discriminate gestures with leave-one-out cross-validation and use the result as a metric to select appropriate finger motions. Our approach provides good results for a number of examples with different gesture types and is validated in a perceptual experiment.
Light transport simulation with vertex connection and merging
Authors: Georgiev Iliyan , Křivánek Jaroslav , Davidovič Tomáš , Slusallek Philipp
Published: November 2012

Developing robust light transport simulation algorithms that are capable of dealing with arbitrary input scenes remains an elusive challenge. Although efficient global illumination algorithms exist, an acceptable approximation error in a reasonable amount of time is usually only achieved for specific types of input scenes. To address this problem, we present a reformulation of photon mapping as a bidirectional path sampling technique for Monte Carlo light transport simulation. The benefit of our new formulation is twofold. First, it makes it possible, for the first time, to explain in a formal manner the relative efficiency of photon mapping and bidirectional path tracing, which have so far been considered conceptually incompatible solutions to the light transport problem. Second, it allows for a seamless integration of the two methods into a more robust combined rendering algorithm via multiple importance sampling. A progressive version of this algorithm is consistent and efficiently handles a wide variety of lighting conditions, ranging from direct illumination, diffuse and glossy inter-reflections, to specular-diffuse-specular light transport. Our analysis shows that this algorithm inherits the high asymptotic performance from bidirectional path tracing for most light path types, while benefiting from the efficiency of photon mapping for specular-diffuse-specular lighting effects.
SURE-based optimization for adaptive sampling and reconstruction
Authors: Li Tzu-Mao , Wu Yu-Ting , Chuang Yung-Yu
Published: November 2012

We apply Stein's Unbiased Risk Estimator (SURE) to adaptive sampling and reconstruction to reduce noise in Monte Carlo rendering. SURE is a general unbiased estimator for mean squared error (MSE) in statistics. With SURE, we are able to estimate error for an arbitrary reconstruction kernel, enabling us to use more effective kernels rather than being restricted to the symmetric ones used in previous work. It also allows us to allocate more samples to areas with higher estimated MSE. Adaptive sampling and reconstruction can therefore be processed within an optimization framework. We also propose an efficient and memory-friendly approach to reduce the impact of noisy geometry features where there is depth of field or motion blur. Experiments show that our method produces images with less noise and crisper details than previous methods.
Adaptive rendering with non-local means filtering
Authors: Rousselle Fabrice , Knaus Claude , Zwicker Matthias
Published: November 2012

We propose a novel approach for image space adaptive sampling and filtering in Monte Carlo rendering. We use an iterative scheme composed of three steps. First, we adaptively distribute samples in the image plane. Second, we denoise the image using a non-linear filter. Third, we estimate the residual per-pixel error of the filtered rendering, and the error estimate guides the sample distribution in the next iteration. The effectiveness of our approach hinges on the use of a state of the art image denoising technique, which we extend to an adaptive rendering framework. A key idea is to split the Monte Carlo samples into two buffers. This improves denoising performance and facilitates variance and error estimation. Our method relies only on the Monte Carlo samples, allowing us to handle arbitrary light transport and lens effects. In addition, it is robust to high noise levels and complex image content. We compare our approach to a state of the art adaptive rendering technique based on adaptive bandwidth selection and demonstrate substantial improvements in terms of both numerical error and visual quality. Our framework is easy to implement on top of standard Monte Carlo renderers and it incurs little computational overhead.
Elasticity-inspired deformers for character articulation
Authors: Kavan Ladislav , Sorkine Olga
Published: November 2012

Current approaches to skeletally-controlled character articulation range from real-time, closed-form skinning methods to offline, physically-based simulation. In this paper, we seek a closed-form skinning method that approximates nonlinear elastic deformations well while remaining very fast. Our contribution is two-fold: (1) we optimize skinning weights for the standard linear and dual quaternion skinning techniques so that the resulting deformations minimize an elastic energy function. We observe that this is not sufficient to match the visual quality of the original elastic deformations and therefore, we develop (2) a new skinning method based on the concept of
joint-based deformers
. We propose a specific deformer which is visually similar to nonlinear variational deformation methods. Our final algorithm is fully automatic and requires little or no input from the user other than a rest-pose mesh and a skeleton. The runtime complexity requires minimal memory and computational overheads compared to linear blend skinning, while producing higher quality deformations than both linear and dual quaternion skinning.
User-guided white balance for mixed lighting conditions
Authors: Boyadzhiev Ivaylo , Bala Kavita , Paris Sylvain , Durand Frédo
Published: November 2012

Proper white balance is essential in photographs to eliminate color casts due to illumination. The single-light case is hard to solve automatically but relatively easy for humans. Unfortunately, many scenes contain multiple light sources such as an indoor scene with a window, or when a flash is used in a tungsten-lit room. The light color can then vary on a per-pixel basis and the problem becomes challenging at best, even with advanced image editing tools.

We propose a solution to the ill-posed mixed light white balance problem, based on user guidance. Users scribble on a few regions that should have the same color, indicate one or more regions of neutral color, and select regions where the current color looks correct. We first expand the provided scribble groups to more regions using pixel similarity and a robust voting scheme. We formulate the spatially varying white balance problem as a sparse data interpolation problem in which the user scribbles and their extensions form constraints. We demonstrate that our approach can produce satisfying results on a variety of scenes with intuitive scribbles and without any knowledge about the lights.
Robust patch-based hdr reconstruction of dynamic scenes
Authors: Sen Pradeep , Kalantari Nima Khademi , Yaesoubi Maziar , Darabi Soheil , Goldman Dan B. , Shechtman Eli
Published: November 2012

High dynamic range (HDR) imaging from a set of sequential exposures is an easy way to capture high-quality images of static scenes, but suffers from artifacts for scenes with significant motion. In this paper, we propose a new approach to HDR reconstruction that draws information from all the exposures but is more robust to camera/scene motion than previous techniques. Our algorithm is based on a novel patch-based energy-minimization formulation that integrates alignment and reconstruction in a joint optimization through an equation we call the HDR image synthesis equation. This allows us to produce an HDR result that is aligned to one of the exposures yet contains information from all of them. We present results that show considerable improvement over previous approaches.
Building a low cost low power wireless network to enable voice communication in developing regions
Authors: Gabale Vijay , Patani Jeet , Mehta Rupesh , Kalyanaraman Ramakrishnan , Raman Bhaskaran
Published: November 2012

In this work, we describe our experiences in building a low cost and low power wireless mesh network using IEEE 802.15.4 technology to provide telephony services in rural regions of the developing world. 802.15.4 was originally designed for a completely different application space of non-real-time, low data rate embedded wireless sensing. We use it to design and prototype a telephony system, which we term as Lo
3
(Low cost, Low power, Local voice). Lo
3
primarily provides two use cases; (1) local and broadcast voice within the wireless mesh network, and (2) remote voice to a phone in the outside world. A Lo
3
network can cost as less as $2K, and can last for several days without power "off the grid", thus making it an ideal choice to meet cost and power constraints of rural regions. We test deployed a full-fledged Lo
3
system in a village near Mumbai, India for 18 hours over 3 days. We established voice calls with an end-to-end latency of less than 120ms, with an average packet loss of less than 2%, and a MOS of 3.6 which is considered as good in practice. The users too gave a positive response to our system. We also tested Lo
3
within our department where it can be used as a wireless intercom service. To our knowledge, Lo
3
is the first system to enable such a voice communication system using 802.15.4 technology, and show its effectiveness in operational settings.
What's app?
Authors: d'Heureuse Nico , Huici Felipe , Arumaithurai Mayutan , Ahmed Mohamed , Papagiannaki Konstantina , Niccolini Saverio
Published: November 2012

In the last few years, smartphones have been gaining ground, both in terms of units shipped as well as in the amount of revenue that companies make selling apps for them. In this paper we present a large-scale study of the application markets where these apps are sold. To the best of our knowledge, this study constitutes the largest public, cross-market, temporal measurement analysis of app statistics to date. We provide insights into a number of areas, including market growth (during our crawl 22% more apps were added to the Google market than the Apple one), app pricing (the BlackBerry and Apple markets are the most expensive on average), as well as a number of other topics such as app sizes, ratings, downloads and top vendors.
Expert testimony
Authors: Rayanchu Shravan
Published: November 2012

Welcome to the Expert Testimony series, where we interview the leading researchers in mobile computing and wireless networking to get their perspectives on their work, and their thoughts on the evolution of the field.

In this issue, we have an interview with Charles E. (Charlie) Perkins conducted by Shravan Rayanchu. Charles E. Perkins is a senior principal engineer at Futurewei, investigating mobile wireless networking and dynamic configuration protocols, in particular LTE and various IEEE and IETF efforts. He is serving as document editor for the 802.21 group of the IEEE, and is author or co-author of IETF standards-track documents in the dmm, mip4, mext, manet, dhc, and autoconf working groups. He is an editor for several journals in areas related to wireless networking. He has continued strong involvement with performance issues related to Internet access for billions of portable wireless devices as well as actitivies for ad hoc networking and scalability.

Charles has authored and edited books on Mobile IP and Ad Hoc Networking, and has published a number of papers and award winning articles in the areas of mobile networking, ad-hoc networking, route optimization for mobile networking, resource discovery, and automatic configuration for mobile computers. Charles was also one of the creators of MobiHoc, the premier conference series that has provided the forum for many of the most important publications in the field of ad hoc networking; he remains on the steering committee for that conference. He has served as general chair and Program Committee chair for MobiHoc, MASS 2006, ICWUS 2010, and other conferences and workshops. Charles has served on the Internet Architecture Board (IAB) of the IETF and, at last count, has authored or co-authored at least 25 RFCs. He has made numerous inventions and been awarded dozens of patents; he was recently nominated for Inventor of the Year by the European Patent Office. He has served on various committees for the National Research Council, as well as numerous technical assessment boards for Army Research Lab and the Swiss MICS program. He has also served as associate editor for Mobile Communications and Computing Review, the official publication of ACM SIGMOBILE, and has served on the editorial staff for IEEE Internet Computing magazine.
Comparison of brown and white adipose tissue fat fractions inob, seipin, andFsp27gene knockout mice by chemical shift-selective imaging and1H-MR spectroscopy
Authors: Peng Xin-Gui , Ju Shenghong , Fang Fang , Wang Yu , Fang Ke , Cui Xin , Liu George , Li Peng , Mao Hui , Teng Gao-Jun
Published: November 2012

Brown adipose tissue (BAT) plays a key role in thermogenesis to protect the body from cold and obesity. White adipose tissue (WAT) stores excess energy in the form of triglycerides. To better understand the genetic effect on regulation of WAT and BAT, we investigated the fat fraction (FF) in two types of adipose tissues in ob/ob, human BSCL2/ seipin gene knockout (SKO), Fsp27 gene knockout ( Fsp27−/−), and wild-type (WT) mice in vivo using chemical shift selective imaging and1H-MR spectroscopy. We reported that the visceral fat volume in WAT was significantly larger in ob/ob mice, but visceral fat volumes were lower in SKO and Fsp27−/−mice compared with WT mice. BAT FF was significantly higher in ob/ob mice than the WT group and similar to that of WAT. In contrast, WAT FFs in SKO and Fsp27−/−mice were lower and similar to that of BAT. The adipocyte size of WAT in ob/ob mice and the BAT adipocyte size in ob/ob, SKO, and Fsp27 mice were significantly larger compared with WT mice. However, the WAT adipocyte size was significantly smaller in SKO mice than in WT mice. Positive correlations were observed between the adipocyte size and FFs of WAT and BAT. These results suggested that smaller adipocyte size correlates with lower FFs of WAT and BAT. In addition, the differences in FFs in WAT and BAT measured by MR methods in different mouse models were related to the different regulation effects of ob, seipin, or Fsp27 gene on developing WAT and BAT.
Improved glycemic control in mice lacking Sglt1 and Sglt2
Authors: Powell David R. , DaCosta Christopher M. , Gay Jason , Ding Zhi-Ming , Smith Melinda , Greer Jennifer , Doree Deon , Jeter-Jones Sabrina , Mseeh Faika , Rodriguez Lawrence A. , Harris Angela , Buhring Lindsey , Platt Kenneth A. , Vogel Peter , Brommage Robert , Shadoan Melanie K. , Sands Arthur T. , Zambrowicz Brian
Published: November 2012

Sodium-glucose cotransporter 2 (SGLT2) is the major, and SGLT1 the minor, transporter responsible for renal glucose reabsorption. Increasing urinary glucose excretion (UGE) by selectively inhibiting SGLT2 improves glycemic control in diabetic patients. We generated Sglt1 and Sglt2 knockout (KO) mice, Sglt1/Sglt2 double-KO (DKO) mice, and wild-type (WT) littermates to study their relative glycemic control and to determine contributions of SGLT1 and SGLT2 to UGE. Relative to WTs, Sglt2 KOs had improved oral glucose tolerance and were resistant to streptozotocin-induced diabetes. Sglt1 KOs fed glucose-free high-fat diet (G-free HFD) had improved oral glucose tolerance accompanied by delayed intestinal glucose absorption and increased circulating glucagon-like peptide-1 (GLP-1), but had normal intraperitoneal glucose tolerance. On G-free HFD, Sglt2 KOs had 30%, Sglt1 KOs 2%, and WTs <1% of the UGE of DKOs. Consistent with their increased UGE, DKOs had lower fasting blood glucose and improved intraperitoneal glucose tolerance than Sglt2 KOs. In conclusion, 1) Sglt2 is the major renal glucose transporter, but Sglt1 reabsorbs 70% of filtered glucose if Sglt2 is absent; 2) mice lacking Sglt2 display improved glucose tolerance despite UGE that is 30% of maximum; 3) Sglt1 KO mice respond to oral glucose with increased circulating GLP-1; and 4) DKO mice have improved glycemic control over mice lacking Sglt2 alone. These data suggest that, in patients with type 2 diabetes, combining pharmacological SGLT2 inhibition with complete renal and/or partial intestinal SGLT1 inhibition may improve glycemic control over that achieved by SGLT2 inhibition alone.
Circuit mechanisms revealed by spike-timing correlations in macaque area MT
Authors: Huang Xin , Lisberger Stephen G.
Published: November 2012

We recorded simultaneously from pairs of motion-sensitive neurons in the middle temporal cortex (MT) of macaque monkeys and used cross-correlations in the timing of spikes between neurons to gain insights into cortical circuitry. We characterized the time course and stimulus dependency of the cross-correlogram (CCG) for each pair of neurons and of the auto-correlogram (ACG) of the individual neurons. For some neuron pairs, the CCG showed negative flanks that emerged next to the central peak during stimulus-driven responses. Similar negative flanks appeared in the ACG of many neurons. Negative flanks were most prevalent and deepest when the neurons were driven to high rates by visual stimuli that moved in the neurons' preferred directions. The temporal development of the negative flanks in the CCG coincided with a parallel, modest reduction of the noise correlation between the spike counts of the neurons. Computational analysis of a model cortical circuit suggested that negative flanks in the CCG arise from the excitation-triggered mutual cross-inhibition between pairs of excitatory neurons. Intracortical recurrent inhibition and afterhyperpolarization caused by intrinsic outward currents, such as the calcium-activated potassium current of small conductance, can both contribute to the negative flanks in the ACG. In the model circuit, stronger intracortical inhibition helped to maintain the temporal precision between the spike trains of pairs of neurons and led to weaker noise correlations. Our results suggest a neural circuit architecture that can leverage activity-dependent intracortical inhibition to adaptively modulate both the synchrony of spike timing and the correlations in response variability.
Channel Identification Machines
Authors: Lazar Aurel A. , Slutskiy Yevgeniy B.
Published: November 2012

We present a formal methodology for identifying a channel in a system consisting of a communication channel in cascade with an asynchronous sampler. The channel is modeled as a multidimensional filter, while models of asynchronous samplers are taken from neuroscience and communications and include integrate-and-fire neurons, asynchronous sigma/delta modulators and general oscillators in cascade with zero-crossing detectors. We devise channel identification algorithms that recover a projection of the filter(s) onto a space of input signals loss-free for both scalar and vector-valued test signals. The test signals are modeled as elements of a reproducing kernel Hilbert space (RKHS) with a Dirichlet kernel. Under appropriate limiting conditions on the bandwidth and the order of the test signal space, the filter projection converges to the impulse response of the filter. We show that our results hold for a wide class of RKHSs, including the space of finite-energy bandlimited signals. We also extend our channel identification results to noisy circuits.
Association of MICA Alleles with Autoimmune Thyroid Disease in Korean Children
Authors: Cho Won Kyoung , Jung Min Ho , Park So Hyun , Baek In Cheol , Choi Hee-Baeg , Kim Tai-Gyu , Suh Byung-Kyu
Published: November 2012

Background. Major histocompatibility complex class I chain-related gene A (MICA) is a ligand for the activating NKG2D receptor expressed on natural killer (NK) cells. We aimed to assess the association of MICA polymorphism with autoimmune thyroid disease (AITD) in Korean children.Methods. Eighty-one patients with AITD were recruited. We analyzed MICA polymorphisms by PCR-SSP and compared the results with those of 70 healthy controls.Results. In AITD, the allele frequencies of MICA*010 (OR=2.21; 95% CI, 1.30–3.76,P<0.003,Pc<0.042) were higher than those of controls. Patients who did not have thyroid-associated ophthalmopathy showed higher frequencies of MICA*010 (OR=2.99; 95% CI, 1.47–6.08,P<0.003,Pc<0.042) and lower frequencies of MICA*008 (OR=0.08; 95% CI, 0.01–0.62,P<0.001,Pc<0.014) compared to those of controls. HLA-B*46, which shows the strongest association with AITD compared with other HLA alleles, showed the strongest linkage disequilibrium with MICA*010. Analyses of the associations between MICA*010 and HLA-B*46 with AITD suggest an association of the MICA allele with AITD.Conclusions. Our results suggest that innate immunity might contribute to the pathogenesis of AITD.
A New Study on the Parameter Relationships of Planetary Roller Screws
Authors: Ma Shangjun , Liu Geng , Tong Ruiting , Zhang Xiaocai
Published: November 2012

As a more powerful transmission device, planetary roller screws (PRSs) recently have received more attention, compared to conventional ball screws. However, due to the complicated and unclear relationships among the PRS components’ parameters, it is difficult to design high‐quality PRSs. To facilitate the PRS design, a new study on the parameter relationships of PRS is conducted in this work. New models of the axial stiffness and the frictional moment of PRS are developed, and the relationships of the axial stiffness and the frictional moment in terms of contact angle, helical angle, and tooth number of the roller thread are investigated. This study could contribute to the research of PRS to improve its transmission performance, especially to increase its positioning accuracy.
Influence of Training Set Selection in Artificial Neural Network-Based Propagation Path Loss Predictions
Authors: Fernández Anitzine Ignacio , Romo Argota Juan Antonio , Fontán Fernado Pérez
Published: November 2012

This paper analyzes the use of artificial neural networks (ANNs) for predicting the received power/path loss in both outdoor and indoor links. The approach followed has been a combined use of ANNs and ray-tracing, the latter allowing the identification and parameterization of the so-called dominant path. A complete description of the process for creating and training an ANN-based model is presented with special emphasis on the training process. More specifically, we will be discussing various techniques to arrive at valid predictions focusing on an optimum selection of the training set. A quantitative analysis based on results from two narrowband measurement campaigns, one outdoors and the other indoors, is also presented.
A Hybrid Model through the Fusion of Type-2 Fuzzy Logic Systems and Sensitivity-Based Linear Learning Method for Modeling PVT Properties of Crude Oil Systems
Authors: Selamat Ali , Olatunji Sunday Olusanya , Abdul Raheem Abdul Azeez
Published: November 2012

Sensitivity-based linear learning method (SBLLM) has recently been used as a predictive tool due to its unique characteristics and performance, particularly its high stability and consistency during predictions. However, the generalisation capability of SBLLM is sometimes limited depending on the nature of the dataset, particularly on whether uncertainty is present in the dataset or not. Since it made use of sensitivity analysis in relation to the data sets used, it is surely very prone to being affected by the nature of the dataset. In order to reduce the effects of uncertainties in SBLLM prediction and improve its generalisation ability, this paper proposes a hybrid system through the unique combination of type-2 fuzzy logic systems (type-2 FLSs) and SBLLM; thereafter the hybrid system was used to model PVT properties of crude oil systems. Type-2 FLS has been choosen in order to better handle uncertainties existing in datasets beyond the capability of type-1 fuzzy logic systems. In the proposed hybrid, the type-2 FLS is used to handle uncertainties in reservoir data so that the cleaned data from type-2 FLS is then passed to the SBLLM for training and then final prediction using testing dataset follows. Comparative studies have been carried out to compare the performance of the newly proposed T2-SBLLM hybrid system with each of the constituent type-2 FLS and SBLLM. Empirical results from simulation show that the proposed T2-SBLLM hybrid system has greatly improved upon the performance of SBLLM, while also maintaining a better performance above that of the type-2 FLS.
Some Existence Results for Impulsive Nonlinear Fractional Differential Equations with Closed Boundary Conditions
Authors: Ergören Hilmi , Kiliçman Adem
Published: November 2012

We investigate some existence results for the solutions to impulsive fractional differential equations having closed boundary conditions. Our results are based on contracting mapping principle and Burton‐Kirk fixed point theorem.
A New General System of Generalized Nonlinear Mixed Composite‐Type Equilibria and Fixed Point Problems with an Application to Minimization Problems
Authors: Sunthrayuth Pongsakorn , Kumam Poom
Published: November 2012

We introduce a new general system of generalized nonlinear mixed composite‐type equilibria and propose a new iterative scheme for finding a common element of the set of solutions of a generalized equilibrium problem, the set of solutions of a general system of generalized nonlinear mixed composite‐type equilibria, and the set of fixed points of a countable family of strict pseudocontraction mappings. Furthermore, we prove the strong convergence theorem of the purposed iterative scheme in a real Hilbert space. As applications, we apply our results to solve a certain minimization problem related to a strongly positive bounded linear operator. Finally, we also give a numerical example which supports our results. The results obtained in this paper extend the recent ones announced by many others.
A 12 GHz 30 mW 130 nm CMOS Rotary Travelling Wave Voltage Controlled Oscillator
Authors: Jacquemod G. , Ben Abdeljelil F. , Carpineto L. , Tatinian W. , Borgarino M.
Published: November 2012

This paper reports a 12 GHz rotary travelling wave (RTW) voltage controlled oscillator designed in a 130 nm CMOS technology. The phase noise and power consumption performances were compared with the literature and with telecommunication standards for broadcast satellite applications. The RTW VCO exhibits a −106 dBc/Hz at 1 MHz and a 30 mW power consumption with a sensibility of 400 MHz/V. Finally, requirements are given for a PLL implementation of the RTW VCO and simulated results are presented.