bluuebunny/crossref_metadata_2025 huggingface dataset:
Mammary stem cells and the differentiation hierarchy: current status and perspectives
Authors: Visvader Jane E. , Stingl John
Published: June 2014

The mammary epithelium is highly responsive to local and systemic signals, which orchestrate morphogenesis of the ductal tree during puberty and pregnancy. Based on transplantation and lineage tracing studies, a hierarchy of stem and progenitor cells has been shown to exist among the mammary epithelium. Lineage tracing has highlighted the existence of bipotent mammary stem cells (MaSCs) in situ as well as long-lived unipotent cells that drive morphogenesis and homeostasis of the ductal tree. Moreover, there is accumulating evidence for a heterogeneous MaSC compartment comprising fetal MaSCs, slow-cycling cells, and both long-term and short-term repopulating cells. In parallel, diverse luminal progenitor subtypes have been identified in mouse and human mammary tissue. Elucidation of the normal cellular hierarchy is an important step toward understanding the “cells of origin” and molecular perturbations that drive breast cancer.
‘Doubling down’ on the autophagy pathway to suppress tumor growth
Authors: Leidal Andrew M. , Debnath Jayanta
Published: June 2014

In this issue of Genes & Development, Wei and colleagues (pp. 1204–1216) use elegant genetic approaches to simultaneously delete the essential autophagy gene FIP200 (FAK family-interacting protein of 200 kDa) and the signaling adaptor p62/SQSTM1 within established murine tumors, which reveals an unexpected synergism between the autophagy pathway and p62 in driving tumor growth. Intriguingly, these observations suggest that the combined targeting of autophagy and p62 may serve as an effective approach to treat specific cancers.
The Minimal Requirements to Use Calcium Imaging to Analyze ICRAC
Authors: Alansary Dalia , Kilch Tatiana , Holzmann Christian , Peinelt Christine , Hoth Markus , Lis Annette
Published: June 2014

Endogenous calcium release-activated channel (CRAC) currents are usually quite small and not always easy to measure using the patch-clamp technique. While we have, for instance, successfully recorded very small CRAC currents in primary human effector T cells, we have not yet managed to record CRAC in naïve primary human T cells. Many groups, including ours, therefore use Ca2+ imaging technologies to analyze CRAC-dependent Ca2+ influx. However, Ca2+ signals are quite complex and depend on many different transporter activities; thus, it is not trivial to make quantitative statements about one single transporter, in this case CRAC channels. Therefore, a detailed patch-clamp analysis of ICRAC is always preferred. Since many laboratories use Ca2+ imaging for ICRAC analysis, we detail here the minimal requirements for reliable measurements. Ca2+ signals not only depend on the net Ca2+ influx through CRAC channels but also depend on other Ca2+ influx mechanisms, K+ channels or Cl− channels (which determine the membrane potential), Ca2+ export mechanisms like plasma membrane Ca2+ ATPase (PMCA), sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) or Na+–Ca2+ exchangers, and (local) Ca2+ buffering often by mitochondria. In this protocol, we summarize a set of experiments that allow (quantitative) statements about CRAC channel activity using Ca2+ imaging experiments, including the ability to rule out Ca2+ signals from other sources.
Purification of Pericytes from Rodent Optic Nerve by Immunopanning
Authors: Zhou Lu , Sohet Fabien , Daneman Richard
Published: June 2014

This protocol describes the use of immunopanning to purify rodent pericytes from the optic nerve. Immunopanning permits the prospective isolation of pericytes from optic nerve tissue by relying on the binding of pericytes to an anti-PDGFRβ (platelet-derived growth factor receptor beta) antibody adhered to a Petri dish. The cells are viable at the end of this gentle procedure, and they can be analyzed acutely for gene expression or cultured alone or in coculture with other central nervous system (CNS) cell types, including CNS endothelial cells and CNS astrocytes. As written, this procedure is used for isolation of optic nerve pericytes from the rat. The same PDGFRβ antibodies can be used for purifying optic nerve pericytes from the mouse, but alternate negative panning antibodies must be used to ensure that astrocytes do not contaminate the preparation. This procedure can also be modified to purify pericytes from the brain. The same PDGFRβ antibody is used, but additional steps (specific dissections or negative panning) are required to ensure that other PDGFRβ-positive contaminants, including cells from the rostral migratory stream, are depleted from the cell suspension.
RNase Footprinting to Map Sites of RNA–Protein Interactions
Authors: Nilsen Timothy W.
Published: June 2014

The binding of a protein to an RNA sequence protects that the region of the RNA from ribonuclease (RNase) digestion; this protected region is known as the protein's “footprint.” In this protocol, end-labeled RNAs with and without bound protein are digested with RNase, and the products of digestion are analyzed by gel electrophoresis on denaturing polyacrylamide gels. If the experiment is performed properly, a comparison of the banding patterns from the two samples will reveal the binding site of the protein. The binding site—or footprint—will be detected as a region without bands in the protein-bound sample. In the sample without bound protein, the bands should cover the entirety of the RNA molecule. To establish appropriate digestion conditions for the procedure (i.e., ≤1 cleavage event per molecule), it is necessary to titrate the amount of RNase under a range of time and temperature conditions. RNase I cleaves after every nucleotide of RNA and works well under many assay conditions, but other enzymes with different cleavage specificities can also be used. RNase VI is preferable when analyzing structured RNA; RNase A is preferable when using pyrimidine-rich RNAs; and RNase T1 is useful for G-rich RNAs. Choosing enzymes with preference for double-stranded (such as RNase VI) versus single-stranded (such as RNase I) RNA may be helpful. Often, a combination of nucleases is advantageous.
Patch-Clamp Measurement of ICRAC and ORAI Channel Activity
Authors: Alansary Dalia , Kilch Tatiana , Holzmann Christian , Peinelt Christine , Hoth Markus , Lis Annette
Published: June 2014

Depletion of internal Ca2+ stores activates store-operated Ca2+ channels. The most prominent members of this class of channels are Ca2+ release-activated Ca2+ (CRAC) channels, which are present in a variety of cell types including immune cells. CRAC channels are composed of ORAI proteins, which are activated by endoplasmic reticulum-bound STIM proteins on Ca2+ store depletion. The underlying Ca2+ current is called ICRAC, which is required for many cellular functions including T-cell activation, mast cell activation, Ca2+-dependent gene expression, and refilling of internal Ca2+ stores. To analyze ICRAC or the Ca2+ current through heterologously expressed ORAI channels, whole-cell patch clamp is the technique of choice. It allows the direct analysis of ion currents through CRAC/ORAI channels. The patch-clamp technique has been used to determine selectivity, permeability, rectification, inactivation, and several other biophysical and pharmacological properties of the channels, and is the most direct and reliable technique to analyze ICRAC.
Purification and Culture of Central Nervous System Pericytes
Authors: Zhou Lu , Sohet Fabien , Daneman Richard
Published: June 2014

Pericytes are found on the abluminal surface of endothelial tubes. The function of these cells is still being elucidated, but they have been shown to be important for development and maintenance of the blood–brain barrier, regulation of angiogenesis and capillary blood flow, and regulation of the neural response to injury and disease. Previously used methods to isolate pericytes have relied on negative selection and prolonged culture of microvessel cells and may lead to populations of pericytes contaminated by other neural cell types. We have developed an immunopanning protocol to specifically purify pericytes from capillaries in the rodent optic nerve. This method relies on a combination of negative and positive selection criteria and allows prospective, acute isolation of pericytes. Use of this method will facilitate studies of pericyte cell biology and function and pericyte–endothelial cell interactions.
Neither confirm nor deny: WikiLeaks evidence and the Vienna Convention on Diplomatic Relations in the judicial review of the Chagos Marine Protected Area (Respond to this article at http://www.therai.org.uk/at/debate)
Authors: Jeffery Laura
Published: June 2014

The Chagos Islanders have faced various legal barriers in their campaign for the right of return to the Chagos Archipelago. Here, Laura Jeffery presents one more twist in this long winding road, namely how the courts regard WikiLeaks evidence revealing how British politicians hatched plans to turn these islands into a nature reserve, thus effectively maintaining the status quo of the existing no‐return policy.
The death of the right‐to‐die campaigners (Respond to this article at http://www.therai.org.uk/at/debate)
Authors: Richards Naomi
Published: June 2014

The ‘right‐to‐die’ or assisted suicide debate in the UK has recently been dominated by high‐profile litigation which has brought to public attention stories of individual suffering. The most recent case is that of Tony Nicklinson who, as a result of his permanent and total paralysis which he said made his life ‘intolerable’, wanted the courts to allow a doctor to end his life. Only six days after a Judicial Review refused his request, Tony died of ‘natural’ causes. This article compares the presentation by the media of Tony's requested death with his actual death and discusses what this reveals more generally about the way in which the right‐to‐die debate is presented to the public. It argues that in a politicised debate in which the personal stories of the disabled‐dying are given airtime because of their didactic or symbolic potential, actual death becomes less important than the rights‐rhetoric surrounding death.
Connecting stressors, ocean ecosystem services, and human health
Authors: Sandifer Paul A. , Sutton‐Grier Ariana E.
Published: June 2014

Ocean and coastal ecosystems provide many critical ecosystem services that support human health and well‐being including providing food, storm protection, and carbon sequestration. Environmental stressors acting individually or concurrently and synergistically are reducing the ability of coastal ecosystems to provide key ecosystem services that may result in decreases in human health and well‐being. We outline some impacts to human health and well‐being that may result from the effects on coastal and ocean ecosystem services of five example stressors: rising temperatures, nutrient enrichment, ocean acidification, habitat destruction and the concomitant loss of biodiversity, and extreme weather events. We conclude with suggestions for research and related actions to improve our understanding and management of coastal ecosystems. These include the need for natural and biomedical/public health scientists, and their respective professional organizations, to work together to increase understanding of the connections between healthy and degraded coastal and marine ecosystems and human health, and for policy and decision‐makers to account for these impacts when considering trade‐offs among management alternatives.
REIT and Commercial Real Estate Returns: A Postmortem of the Financial Crisis
Authors: Sun Libo , Titman Sheridan D. , Twite Garry J.
Published: June 2014

In the years surrounding the financial crisis, the share prices of equity Real Estate Investment Trusts (REITs) were much more volatile than the underlying commercial real estate prices. To better understand this phenomenon we examine the cross‐sectional dispersion of REIT returns during this time period with a particular focus on the influence of their capital structures. By looking at both the debt ratio and the maturity structure of the debt, we separate the pure leverage effect from the effect of financial distress. Consistent with leverage and financial distress costs amplifying the price decline, we find that the share prices of REITs with higher debt‐to‐asset ratios and shorter maturity debt fell more during the 2007 to early‐2009 crisis period. Although REIT prices rebounded with the bounce back in commercial real estate prices, financial distress costs had a permanent effect on REIT values. In particular, we find that REITs with more debt due during the crisis period tended to sell more property and issue more equity in 2009, when prices were depressed.
Auction versus Negotiated Sale: Evidence from Real Estate Sales
Authors: Chow Yuen Leng , Hafalir Isa E. , Yavas Abdullah
Published: June 2014

We offer a theoretical and empirical comparison of auctions and negotiated sales. We first build a simple model to show that auctions generate a higher relative price than negotiated sales when demand for the asset is strong, when the asset is more homogeneous and when the asset attracts buyers with higher valuations. Using data from property sales in Singapore, we find support for our theoretical predictions. In addition, we find that auctions do not necessarily generate a higher price premium for foreclosed properties than for nonforeclosed properties.
The Leveraged City
Authors: You Seung Dong
Published: June 2014

This study analyzes the effects of leverage on real estate developments. In urban growth models, a real estate developer converts land from agricultural to urban use. At the time at which such a land conversion occurs, a developer who maximizes the equity value obtains a defaultable construction loan at fair market value. By presenting a more general form of the irreversibility premium of Capozza and Helsley, I show that, with more leverage, uncertainty is less of a deterrent to the land conversion. Under uncertainty, a leveraged developer exercises the land conversion option earlier than an unleveraged developer would. Leverage expands equilibrium city size.
Reputation and talent mobility in theAsiaPacific
Authors: Harvey William S , Groutsis Dimitria
Published: June 2014

This paper argues that different forms of reputation are important for the attraction and retention of talent. Drawing upon the skilled migration literature as well as examples from national governments, supranational organisations and the mass media, we provide a typology that highlights the intersections between reputation and talent mobility. We provide three important contributions. First, we illustrate that reputation plays a central role in the global competition for talent. Second, we highlight that the reputations of countries affect the attraction and retention of top workers. Third, we show that global talent is not only influenced by country reputation but also produces reputations which manifest at the individual level through the inflow and outflow of talent. These contributions shed new theoretical and practical insights on the importance and impact of reputation for talent mobility.
The Peri‐procedural Use of Dabigatran in Patients Undergoing Left Atrial Ablation for Atrial Fibrillation
Authors: Somani Riyaz , Mohajer Kiarash , Haley Charlotte , Simpson Christopher S. , Abdollah Hoshiar , Baranchuk Adrian , Redfearn Damian P. , Michael Kevin
Published: June 2014

Introduction

Pulmonary vein isolation is an effective strategy in patients with atrial fibrillation (AF). The peri‐procedural use of anticoagulation is routinely employed to reduce thromboembolic risk.

Aims/Methods

The aim of this study was to compare the use of Dabigatran to the other 2 strategies involving the use of Warfarin. Single centre observational study comparing 3 anticoagulation strategies: Group 1 consisted of patients maintained on Warfarin (5.15 ± 2.52 mg) with a therapeutic INR of 2–3. Group 2 comprised patients initially treated with Warfarin (6.98 ± 3.17 mg), which was discontinued 1 week prior to LA ablation, during which time patients were bridged with a therapeutic dose of Dalteparin. Group 3 included patients anticoagulated with Dabigatran (40 patients received 150 mg BID, 3 patients received 110 mg BID), which was discontinued 24–30 h prior to the procedure.

Results

A total of 207 patients were included in the study. There were no significant differences in age, sex, LA volume, CHADS2 score or proportion of patients with persistent AF. There were no significant differences in the number of patients with intra‐cardiac thrombus found at TOE (Group 1: 2.3% vs. Group 2: 1.5% vs. Group 3: 0%; P = 0.37). Furthermore, there were no differences in the rate of groin hematoma (2.2% vs. 1.5% vs. 2.3%; P = 0.8) or the development of pericardial effusion (5.4% vs. 8.8% vs. 2.3%; P = 0.54). No thromboembolic events were seen.

Conclusion

Peri‐procedural use of Dabigatran during AF ablation procedures is safe, with no significant difference when compared to conventional anticoagulation with either Warfarin bridged with Dalteparin or uninterrupted Warfarin.
Clinical and economic impact of a switch from high‐ to low‐volume renal replacement therapy in patients with acute kidney injury
Authors: Paterson A. L. , Johnston A. J. , Kingston D. , Mahroof R.
Published: June 2014

High‐intensity renal replacement therapy protocols in intensive care patients with acute kidney injury have failed to translate to improved patient outcomes when compared with lower‐intensity protocols. This retrospective study explored the clinical and economic impacts of switching from a 30–35 ml.kg−1.h−1 (high‐volume) to a 20 ml.kg−1.h−1 (low‐volume) protocol. Patients (n = 366) admitted 12 months before (n = 187) and after (n = 179) the switch were included in the study. There was no difference in in‐hospital mortality (77/187 (41%) vs 75/179 (42%), respectively, p = 0.92), intensive care unit mortality (55/187 (29%) vs 61/179 (34%), respectively, p = 0.40), duration of organ support or extent of renal recovery between the high‐ and low‐volume cohorts. A 25% reduction in daily replacement fluid usage was observed, equating to a cost saving of over £27 000 per annum. In conclusion, a switch from high‐ to low‐volume continuous haemodiafiltration had minimal effects on clinical outcomes and resulted in marked cost savings.
Complex epidermal organs of Phascolion (Sipuncula): insights into the evolution of bimodal secretory cells in annelids
Authors: Müller Carsten H.G. , Hylleberg Jørgen , Michalik Peter
Published: June 2014

The epidermal organs of an undescribed Phascolion species from the Balearic Islands were investigated using SEM, TEM, LM, CLSM and μCT methods. We found axial receptor cells confirming the previously assumed sensory function of epidermal organs. Our analyses also revealed six types of secretory cells. Some secretory cells types are capable of secreting filamentous and amorphous secretion in two different ways simultaneously (bimodal secretion). The high diversity of cell types, the complex pattern of acinar units, and the absence of a common gland pore make epidermal organs of Phascolion unique amongst sipunculans (Phascolion type). Our reconstruction of the evolution of the epidermal organs of Sipuncula revealed that Phascolion‐type epidermal organs may have derived from either Golfingia‐, Sipunculus‐ or Phascolosoma‐type epidermal organs. The oldest known sipunculans were Golfingia‐like and had epidermal organs, which might resemble the architecture of the Golfingia‐type epidermal organs in extant taxa. Thus, it can be hypothesized that bimodal secretory cells (e.g. basophilic secretory cells) were part of the sipunculan ground pattern. Moreover, bimodal secretory cells of Phascolion look strikingly similar to those found in various annelid glands and thus might even be part of the ground pattern of stem species of Sipuncula + Pleistoannelida.
Reconciling Traditional Morality and the Morality of Competition
Authors: Bailey Adam D.
Published: June 2014

It is commonly believed that the moral norms of “everyday” or “traditional” morality apply uniformly in all business contexts. However, Joseph Heath has recently argued that this is not the case. According to Heath, the norms of everyday morality apply with respect to “administered” transactions but not “market” transactions. Market transactions are, he argues, governed by a distinct, “adversarial” morality. In this article, I argue that Heath's attempt to show that competitive contexts are governed by a distinct, adversarial morality does not succeed. I then undertake the task of showing that, contrary to what is commonly thought, competitive actions can be reconciled with the norms of traditional morality.
Perceived marginalization and aggression: A longitudinal study with low‐educated adolescents
Authors: Issmer Christian , Wagner Ulrich
Published: June 2014

Social exclusion can evoke aggression. In the past two decades research has demonstrated this effect both for interpersonal and societal forms of exclusion. In addition, recent violent uprisings, like the London riots in August 2011, have been linked to social exclusion in the media. However, so far there is a lack of longitudinal studies which examine the aggression‐enhancing effect of societal‐level exclusion (i.e., marginalization) in disadvantaged groups. This research investigates the impact of perceived marginalization on aggression in a sample of N = 181 adolescents with a low educational background by means of a two‐wave longitudinal study. The results of structural equation analyses are consistent with the hypothesis that perceived marginalization enhances aggression, and that this effect is mediated by the extent of negative societal meta‐stereotypes. Furthermore, the reverse path from aggression to perceptions of marginalization is also significant. We discuss the implications of these findings and highlight practical consequences.
Identification of 1, 4‐Dihydrothieno[3′, 2′:5, 6]thiopyrano[4, 3‐c]pyrazole Derivatives as Human 5‐Lipo‐oxygenase Inhibitors
Authors: Hu Jianshu , Zhu Wei , Meng Hu , Liu Ying , Wang Xin , Hu Chun
Published: June 2014

A series of novel 1,4‐dihydrothieno[3′,2′:5,6]thiopyrano[4,3‐c]‐pyrazole‐3‐carboxamide derivatives were synthesized and evaluated for their inhibitory activity to human 5‐lipo‐oxygenase (5‐LOX). Compound 7c was found to exhibit significant inhibition to human 5‐LOX with IC50 value of 5.7 ± 0.9 μm. Compound 7c was further studied using molecular docking in order to delineate its structure–activity relationship and to gain insight into the design of effective 5‐LOX inhibitors.
Design, Synthesis, and Antimicrobial Evaluation of Hexadentate Hydroxypyridinones with High Iron(III) Affinity
Authors: Zhang Ming‐Xia , Zhu Chun‐Feng , Zhou Ying‐Jun , Kong Xiao‐Le , Hider Robert C , Zhou Tao
Published: June 2014

A range of hexadentate 3‐hydroxypyridin‐4‐ones (HPOs) with high affinity for iron(III) has been synthesized. The log stability constants of two HPO–iron complexes (logK1) were determined to be over 34, and pFe values of the two HPOs were determined to be over 31. Antimicrobial assay indicated that they are able to markedly inhibit the growth of both Gram‐positive and Gram‐negative bacteria. Compounds 14a and 14e were found to exhibit the strongest inhibitory activity against Staphyloccocus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and Escherichia coli, with MIC values of 8, 8, 16, and 8 μg/mL, respectively. These results indicate that hexadentate 3‐hydroxypyridin‐4‐ones have potential application as antimicrobial agents, especially in the treatment of wound infection.
Structure‐based Design, Synthesis, and Biological Evaluation of Isatin Derivatives as Potential Glycosyltransferase Inhibitors
Authors: Wang Yong , Chan Fung‐Yi , Sun Ning , Lui Hok‐Kiu , So Pui‐Kin , Yan Siu‐Cheong , Chan Kin‐Fai , Chiou Jiachi , Chen Sheng , Abagyan Ruben , Leung Yun‐Chung , Wong Kwok‐Yin
Published: June 2014

Peptidoglycan glycosyltransferase (PGT) has been shown to be an important pharmacological target for the inhibition of bacterial cell wall biosynthesis. Structure‐based virtual screening of about 3 000 000 commercially available compounds against the crystal structure of the glycosyltransferase (GT) domain of the Staphylococcus aureus penicillin‐binding protein 2 (S. aureus PBP2) resulted in identification of an isatin derivative, 2‐(3‐(2‐carbamimidoylhydrazono)‐2‐oxoindolin‐1‐yl)‐N‐(m‐tolyl)acetamide (4) as a novel potential GT inhibitor. A series of 4 derivatives were synthesized. Several compounds showed more active antimicrobial activity than the initial hit compound 4, in particular 2‐(3‐(2‐carbamimidoylhydrazono)‐2‐oxoindolin‐1‐yl)‐N‐(3‐nitrophenyl)acetamide (4l), against Gram‐positive Bacillus subtilis and S. aureus with MIC values of 24 and 48 μg/mL, respectively. Saturation transfer difference (STD) NMR study revealed that there is a binding contact between 4l and the GT domain of S. aureus PBP2. Competitive STD‐NMR further proved that 4l and moenomycin A bind to GT domain in a competitive manner. Molecular docking study suggests a potential binding pocket of 4l in the GT domain of S. aureus PBP2. Taken together, compound 4l would provide a new scaffold for further development of potent GT inhibitors.
Object detection and classification from large‐scale cluttered indoor scans
Authors: Mattausch Oliver , Panozzo Daniele , Mura Claudio , Sorkine‐Hornung Olga , Pajarola Renato
Published: June 2014

We present a method to automatically segment indoor scenes by detecting repeated objects. Our algorithm scales to datasets with 198 million points and does not require any training data. We propose a trivially parallelizable preprocessing step, which compresses a point cloud into a collection of nearly‐planar patches related by geometric transformations. This representation enables us to robustly filter out noise and greatly reduces the computational cost and memory requirements of our method, enabling execution at interactive rates. We propose a patch similarity measure based on shape descriptors and spatial configurations of neighboring patches. The patches are clustered in a Euclidean embedding space based on the similarity matrix to yield the segmentation of the input point cloud. The generated segmentation can be used to compress the raw point cloud, create an object database, and increase the clarity of the point cloud visualization.
Detection and reconstruction of freeform sweeps
Authors: Bartoň M. , Pottmann H. , Wallner J.
Published: June 2014

We study the difficult problem of deciding if parts of a freeform surface can be generated, or approximately generated, by the motion of a planar profile through space. While this task is basic for understanding the geometry of shapes as well as highly relevant for manufacturing and building construction, previous approaches were confined to special cases like kinematic surfaces or “moulding” surfaces. The general case remained unsolved so far. We approach this problem by a combination of local and global methods: curve analysis with regard to “movability”, curve comparison by common substring search in curvature plots, an exhaustive search through all planar cuts enhanced by quick rejection procedures, the ordering of candidate profiles and finally, global optimization. The main applications of our method are digital reconstruction of CAD models exhibiting sweep patches, and aiding in manufacturing freeform surfaces by pointing out those parts which can be approximated by sweeps.
Manipulating refractive and reflective binocular disparity
Authors: Dąbała Ł. , Kellnhofer P. , Ritschel T. , Didyk P. , Templin K. , Myszkowski K. , Rokita P. , Seidel H.‐P.
Published: June 2014

Presenting stereoscopic content on 3D displays is a challenging task, usually requiring manual adjustments. A number of techniques have been developed to aid this process, but they account for binocular disparity of surfaces that are diffuse and opaque only. However, combinations of transparent as well as specular materials are common in the real and virtual worlds, and pose a significant problem. For example, excessive disparities can be created which cannot be fused by the observer. Also, multiple stereo interpretations become possible, e. g., for glass, that both reflects and refracts, which may confuse the observer and result in poor 3D experience. In this work, we propose an efficient method for analyzing and controlling disparities in computer‐generated images of such scenes where surface positions and a layer decomposition are available. Instead of assuming a single per‐pixel disparity value, we estimate all possibly perceived disparities at each image location. Based on this representation, we define an optimization to find the best per‐pixel camera parameters, assuring that all disparities can be easily fused by a human. A preliminary perceptual study indicates, that our approach combines comfortable viewing with realistic depiction of typical specular scenes.
Optimizing stereo‐to‐multiview conversion for autostereoscopic displays
Authors: Chapiro Alexandre , Heinzle Simon , Aydın Tunç Ozan , Poulakos Steven , Zwicker Matthias , Smolic Aljosa , Gross Markus
Published: June 2014

We present a novel stereo‐to‐multiview video conversion method for glasses‐free multiview displays. Different from previous stereo‐to‐multiview approaches, our mapping algorithm utilizes the limited depth range of autostereoscopic displays optimally and strives to preserve the scene's artistic composition and perceived depth even under strong depth compression. We first present an investigation of how perceived image quality relates to spatial frequency and disparity. The outcome of this study is utilized in a two‐step mapping algorithm, where we (i) compress the scene depth using a non‐linear global function to the depth range of an autostereoscopic display and (ii) enhance the depth gradients of salient objects to restore the perceived depth and salient scene structure. Finally, an adapted image domain warping algorithm is proposed to generate the multiview output, which enables overall disparity range extension.
Laplacian colormaps: a framework for structure‐preserving color transformations
Authors: Eynard D. , Kovnatsky A. , M. Bronstein M.
Published: June 2014

Mappings between color spaces are ubiquitous in image processing problems such as gamut mapping, decolorization, and image optimization for color‐blind people. Simple color transformations often result in information loss and ambiguities, and one wishes to find an image‐specific transformation that would preserve as much as possible the structure of the original image in the target color space. In this paper, we propose Laplacian colormaps, a generic framework for structure‐preserving color transformations between images. We use the image Laplacian to capture the structural information, and show that if the color transformation between two images preserves the structure, the respective Laplacians have similar eigenvectors, or in other words, are approximately jointly diagonalizable. Employing the relation between joint diagonalizability and commutativity of matrices, we use Laplacians commutativity as a criterion of color mapping quality and minimize it w.r.t. the parameters of a color transformation to achieve optimal structure preservation. We show numerous applications of our approach, including color‐to‐gray conversion, gamut mapping, multispectral image fusion, and image optimization for color deficient viewers.
Content‐aware surface parameterization for interactive restoration of historical documents
Authors: Pal Kazim , Schüller Christian , Panozzo Daniele , Sorkine‐Hornung Olga , Weyrich Tim
Published: June 2014

We present an interactive method to restore severely damaged historical parchments. When damaged by heat in a fire, such manuscripts undergo a complex deformation and contain various geometric distortions such as wrinkling, buckling, and shrinking, rendering them nearly illegible. They cannot be physically flattened due to the risk of further damage. We propose a virtual restoration framework to estimate the non‐rigid deformation the parchment underwent and to revert it, making reading the text significantly easier whilst maintaining the veracity of the textual content. We estimate the deformation by combining automatically extracted constraints with user‐provided hints informed by domain knowledge. We demonstrate that our method successfully flattens and straightens the text on a variety of pages scanned from a 17th century document which fell victim to fire damage.
Efficient Monte Carlo rendering with realistic lenses
Authors: Hanika Johannes , Dachsbacher Carsten
Published: June 2014

In this paper we present a novel approach to simulate image formation for a wide range of real world lenses in the Monte Carlo ray tracing framework. Our approach sidesteps the overhead of tracing rays through a system of lenses and requires no tabulation. To this end we first improve the precision of polynomial optics to closely match ground‐truth ray tracing. Second, we show how the Jacobian of the optical system enables efficient importance sampling, which is crucial for difficult paths such as sampling the aperture which is hidden behind lenses on both sides. Our results show that this yields converged images significantly faster than previous methods and accurately renders complex lens systems with negligible overhead compared to simple models, e.g. the thin lens model. We demonstrate the practicality of our method by incorporating it into a bidirectional path tracing framework and show how it can provide information needed for sophisticated light transport algorithms.
Interactive cloth rendering of microcylinder appearance model under environment lighting
Authors: Iwasaki K. , Mizutani K. , Dobasbi Y. , Nisbita T.
Published: June 2014

This paper proposes an interactive rendering method of cloth fabrics under environment lighting. The outgoing radiance from cloth fabrics in the microcylinder model is calculated by integrating the product of the distant environment lighting, the visibility function, the weighting function that includes shadowing/masking effects of threads, and the light scattering function of threads. The radiance calculation at each shading point of the cloth fabrics is simplified to a linear combination of triple product integrals of two circular Gaussians and the visibility function, multiplied by precomputed spherical Gaussian convolutions of the weighting function. We propose an efficient calculation method of the triple product of two circular Gaussians and the visibility function by using the gradient of signed distance function to the visibility boundary where the binary visibility changes in the angular domain of the hemisphere. Our GPU implementation enables interactive rendering of static cloth fabrics with dynamic viewpoints and lighting. In addition, interactive editing of parameters for the scattering function (e.g. thread's albedo) that controls the visual appearances of cloth fabrics can be achieved.
Compressing dynamic meshes with geometric laplacians
Authors: Váša L. , Marras S. , Hormann K. , Brunnett G.
Published: June 2014

This paper addresses the problem of representing dynamic 3D meshes in a compact way, so that they can be stored and transmitted efficiently. We focus on sequences of triangle meshes with shared connectivity, avoiding the necessity of having a skinning structure. Our method first computes an average mesh of the whole sequence in edge shape space. A discrete geometric Laplacian of this average surface is then used to encode the coefficients that describe the trajectories of the mesh vertices. Optionally, a novel spatio‐temporal predictor may be applied to the trajectories to further improve the compression rate. We demonstrate that our approach outperforms the current state of the art in terms of low data rate at a given perceived distortion, as measured by the STED and KG error metrics.
SimSelect: Similarity‐based selection for 3D surfaces
Authors: Guy Emilie , Thiery Jean‐Marc , Boubekeur Tamy
Published: June 2014

Surface selection is one of the fundamental interactions in shape modeling. In the case of complex models, this task is often tedious for at least two reasons: firstly the local geometry of a given region may be hard to manually select and needs great accuracy; secondly the selection process may have to be repeated a large number of times for similar regions requiring similar subsequent editing. We propose SimSelect, a new system for interactive selection on 3D surfaces addressing these two issues. We cope with the accuracy issue by classifying selections in different types, namely components, parts and patches for which we independently optimize the selection process. Second, we address the repetitiveness issue by introducing an expansion process based on shape recognition which automatically retrieves potential selections similar to the user‐defined one. As a result, our system provides the user with a compact set of simple interaction primitives providing a smooth select‐and‐edit workflow.
SAFE: Structure‐aware facade editing
Authors: Dang Minh , Ceylan Duygu , Neubert Boris , Pauly Mark
Published: June 2014

Many man‐made objects, in particular building facades, exhibit dominant structural relations such as symmetry and regularity. When editing these shapes, a common objective is to preserve these relations. However, often there are numerous plausible editing results that all preserve the desired structural relations of the input, creating ambiguity. We propose an interactive facade editing framework that explores this structural ambiguity. We first analyze the input in a semi‐automatic manner to detect different groupings of the facade elements and the relations among them. We then provide an incremental editing process where a set of variations that preserve the detected relations in a particular grouping are generated at each step. Starting from one input example, our system can quickly generate various facade configurations.
On‐the‐fly generation and rendering of infinite cities on the GPU
Authors: Steinberger Markus , Kenzel Michael , Kainz Bernhard , Wonka Peter , Schmalstieg Dieter
Published: June 2014

In this paper, we present a new approach for shape‐grammar‐based generation and rendering of huge cities in real‐time on the graphics processing unit (GPU). Traditional approaches rely on evaluating a shape grammar and storing the geometry produced as a preprocessing step. During rendering, the pregenerated data is then streamed to the GPU. By interweaving generation and rendering, we overcome the problems and limitations of streaming pregenerated data. Using our methods of visibility pruning and adaptive level of detail, we are able to dynamically generate only the geometry needed to render the current view in real‐time directly on the GPU. We also present a robust and efficient way to dynamically update a scene's derivation tree and geometry, enabling us to exploit frame‐to‐frame coherence. Our combined generation and rendering is significantly faster than all previous work. For detailed scenes, we are capable of generating geometry more rapidly than even just copying pregenerated data from main memory, enabling us to render cities with thousands of buildings at up to 100 frames per second, even with the camera moving at supersonic speed.
Dual‐color mixing for fused deposition modeling printers
Authors: Reiner Tim , Carr Nathan , Měch Radomír , Št'ava Ondřej , Dachsbacher Carsten , Miller Gavin
Published: June 2014

In this work we detail a method that leverages the two color heads of recent low‐end fused deposition modeling (FDM) 3D printers to produce continuous tone imagery. The challenge behind producing such two‐tone imagery is how to finely interleave the two colors while minimizing the switching between print heads, making each color printed span as long and continuous as possible to avoid artifacts associated with printing short segments. The key insight behind our work is that by applying small geometric offsets, tone can be varied without the need to switch color print heads within a single layer. We can now effectively print (two‐tone) texture mapped models capturing both geometric and color information in our output 3D prints.
Multi‐style paper pop‐up designs from 3D models
Authors: Ruiz Conrado R. , Le Sang N. , Yu Jinze , Low Kok‐Lim
Published: June 2014

Paper pop‐ups are interesting three‐dimensional books that fascinate people of all ages. The design and construction of these pop‐up books however are done manually and require a lot of time and effort. This has led to computer‐assisted or automated tools for designing paper pop‐ups. This paper proposes an approach for automatically converting a 3D model into a multi‐style paper pop‐up. Previous automated approaches have only focused on single‐style pop‐ups, where each is made of a single type of pop‐up mechanisms. In our work, we combine multiple styles in a pop‐up, which is more representative of actual artist's creations. Our method abstracts a 3D model using suitable primitive shapes that both facilitate the formation of the considered pop‐up mechanisms and closely approximate the input model. Each shape is then abstracted using a set of 2D patches that combine to form a valid pop‐up. We define geometric conditions that ensure the validity of the combined pop‐up structures. In addition, our method also employs an image‐based approach for producing the patches to preserve the textures, finer details and important contours of the input model. Finally, our system produces a printable design layout and decides an assembly order for the construction instructions. The feasibility of our results is verified by constructing the actual paper pop‐ups from the designs generated by our system.
Accurate and efficient lighting for skinned models
Authors: Tarini Marco , Panozzo Daniele , Sorkine‐Hornung Olga
Published: June 2014

In the context of real‐time, GPU‐based rendering of animated skinned meshes, we propose a new algorithm to compute surface normals with minimal overhead both in terms of the memory footprint and the required per‐vertex operations. By accounting for the variation of the skinning weights over the surface, we achieve a higher visual quality compared to the standard approximation ubiquitously used in video‐game engines and other real‐time applications. Our method supports Linear Blend Skinning and Dual Quaternion Skinning. We demonstrate the advantages of our technique on a variety of datasets and provide a complete open‐source implementation, including GLSL shaders.
Deformation with enforced metrics on length, area and volume
Authors: Jin Shuo , Zhang Yunbo , C.L. Wang Charlie
Published: June 2014

Techniques have been developed to deform a mesh with multiple types of constraints. One limitation of prior methods is that the accuracy of demanded metrics on the resultant model cannot be guaranteed. Adding metrics directly as hard constraints to an optimization functional often leads to unexpected distortion when target metrics differ significant from what are on the input model. In this paper, we present an effective framework to deform mesh models by enforcing demanded metrics on length area and volume. To approach target metrics stably and minimize distortion, an iterative scale‐driven deformation is investigated, and a global optimization functional is exploited to balance the scaling effect at different parts of a model. Examples demonstrate that our approach provides a user‐friendly tool for designers who are used to semantic input.
ExploreMaps: Efficient construction and ubiquitous exploration of panoramic view graphs of complex 3D environments
Authors: Di Benedetto M. , Ganovelli F. , Balsa Rodriguez M. , Jaspe Villanueva A. , Scopigno R. , Gobbetti E.
Published: June 2014

We introduce a novel efficient technique for automatically transforming a generic renderable 3D scene into a simple graph representation named ExploreMaps, where nodes are nicely placed point of views, called probes, and arcs are smooth paths between neighboring probes. Each probe is associated with a panoramic image enriched with preferred viewing orientations, and each path with a panoramic video. Our GPU‐accelerated unattended construction pipeline distributes probes so as to guarantee coverage of the scene while accounting for perceptual criteria before finding smooth, good looking paths between neighboring probes. Images and videos are precomputed at construction time with off‐line photorealistic rendering engines, providing a convincing 3D visualization beyond the limits of current real‐time graphics techniques. At run‐time, the graph is exploited both for creating automatic scene indexes and movie previews of complex scenes and for supporting interactive exploration through a low‐DOF assisted navigation interface and the visual indexing of the scene provided by the selected viewpoints. Due to negligible CPU overhead and very limited use of GPU functionality, real‐time performance is achieved on emerging web‐based environments based on WebGL even on low‐powered mobile devices.
Hierarchical opacity optimization for sets of 3D line fields
Authors: Günther Tobias , Rössl Christian , Theisel Holger
Published: June 2014

The selection of meaningful lines for 3D line data visualization has been intensively researched in recent years. Most approaches focus on single line fields where one line passes through each domain point. This paper presents a selection approach for sets of line fields which is based on a global optimization of the opacity of candidate lines. For this, existing approaches for single line fields are modified such that significantly larger amounts of line representatives are handled. Furthermore, time coherence is addressed for animations, making this the first approach that solves the line selection problem for 3D time‐dependent flow. We apply our technique to visualize dense sets of pathlines, sets of magnetic field lines, and animated sets of pathlines, streaklines and masslines.
Group‐in‐a‐Box Meta‐Layouts for Topological Clusters and Attribute‐Based Groups: Space‐Efficient Visualizations of Network Communities and Their Ties
Authors: Chaturvedi S. , Dunne C. , Ashktorab Z. , Zachariah R. , Shneiderman B.
Published: June 2014

An important part of network analysis is understanding community structures like topological clusters and attribute‐based groups. Standard approaches for showing communities using colour, shape, rectangular bounding boxes, convex hulls or force‐directed layout algorithms remain valuable, however our Group‐in‐a‐Box meta‐layouts add a fresh strategy for presenting community membership, internal structure and inter‐cluster relationships. This paper extends the basic Group‐in‐a‐Box meta‐layout, which uses a Treemap substrate of rectangular regions whose size is proportional to community size. When there are numerous inter‐community relationships, the proposed extensions help users view them more clearly: (1) the Croissant–Doughnut meta‐layout applies empirically determined rules for box arrangement to improve space utilization while still showing inter‐community relationships, and (2) the Force‐Directed layout arranges community boxes based on their aggregate ties at the cost of additional space. Our free and open source reference implementation in NodeXL includes heuristics to choose what we have found to be the preferable Group‐in‐a‐Box meta‐layout to show networks with varying numbers or sizes of communities. Case study examples, a pilot comparative user preference study (nine participants), and a readability measure‐based evaluation of 309 Twitter networks demonstrate the utility of the proposed meta‐layouts.