bluuebunny/crossref_metadata_2025 huggingface dataset:
Phylogeny and the fossil record of the Helophoridae reveal Jurassic origin of extant hydrophiloid lineages (Coleoptera: Polyphaga)
Authors: FIKÁČEK MARTIN , PROKIN ALEXANDER , ANGUS ROBERT B. , PONOMARENKO ALEXANDER , YUE YANLI , REN DONG , PROKOP JAKUB
Published: June 2012

We performed a phylogenetic analysis focused on the hydrophiloid family Helophoridae (Coleoptera: Polyphaga) in order to test the phylogenetic position of selected Mesozoic fossils assigned to the Hydrophiloidea. The analysis is based on 92 characters of larvae and adults, and includes all extant subgenera of Helophorus and representatives of all other extant hydrophiloid families. Based on this analysis, we provide additional evidence for the monophyly of the helophorid lineage containing the families Helophoridae, Georissidae and Epimetopidae, as well as the first hypothesis on the phylogenetic relationships within Helophorus, revealing three main clades: Lihelophorus, Rhopalohelophorus and the clade of sculptured small subgenera; the subgenera Helophorus s.str., Gephelophorus, Trichohelophorus and Transithelophorus are recognized as paraphyletic or polyphyletic. Inclusion of fossil species in the analysis reveals the Mesozoic genera Hydrophilopsia Ponomarenko, Laetopsia Fikáček et al. (adult forms) and Cretotaenia Ponomarenko (larval form) as basal extinct clades of the helophorid lineage, the former genus Mesosperchus Ponomarenko as containing probable stem taxa of Helophorus and the former genus Mesohelophorus Ponomarenko as a member of the Helophorus clade containing extant sculptured subgenera. The extant subgenus Thaumhelophorussyn.nov. is synonymized with Rhopalohelophorus. Our results show that the family Helophoridae may be dated back to the late Jurassic (c. 150 Ma) and the extant clades of Helophorus back to the Early Cretaceous (c. 136 Ma). The basal groups of Helophorus and the supposed basal extinct lineages of the helophorid lineages are shown to be aquatic as adults. A single origin of trichobothria and ventral hydrophobic pubescence in the common ancestor of the Hydrophiloidea is hypothesized, indicating ancestral aquatic habits in the adult stage for the whole Hydrophiloidea.
Systematics and taxonomy of theruficornisgroup of genusMerodonMeigen (Diptera: Syrphidae)
Authors: VUJIĆ ANTE , RADENKOVIĆ SNEŽANA , STåHLS GUNILLA , AČANSKI JELENA , STEFANOVIĆ ANA , VESELIĆ SANJA , ANDRIĆ ANDRIJANA , HAYAT RÜSTEM
Published: June 2012

We revise theruficornisgroup of species ofMerodonMeigen (Diptera, Syrphidae) providing an illustrated key, a discussion of taxonomic characters and a morphological diagnosis. A total of 18 species from theruficornisgroup are treated including distributional data. Descriptions are provided for seven new species:M. gallicusVujić & Radenkovićsp.n.,M. hoplitisHurkmanssp.n.,M. lamellatusVujić & Radenkovićsp.n.,M. nigripodusVujić & Hayatsp.n.,M. ovaloidesVujić & Radenkovićsp.n.,M. ponticusVujić & Radenkovićsp.n., andM. turcicusVujić & Hayatsp.n.The taxonM. auripesSack, is redefined and a neotype designated. Lectotypes are designated forM. graecusLoew;M. planicepsLoew andM. crymensisParamonov. The monophyly and systematic position of this species group was assessed based on parsimony and maximum likelihood analyses of mitochondrial COI and nuclear 28S rDNA sequences. A very high level of endemism was observed in theruficornisspecies group. Among 18 taxa, 12 are limited‐range endemics, present in few mountain areas or in a small part of the total range of the group. These endemics clearly show the importance of geographic isolation in the process of speciation.
Guyiling jianboni gen. et sp.n., an antlion‐like lacewing, illuminating homologies and transformations in Neuroptera wing venation
Authors: SHI CHAOFAN , BÉTHOUX OLIVIER , SHIH CHUNGKUN , REN DONG
Published: June 2012

A new genus and species of antlion‐like fossil lacewing, Guyiling jianbonigen. et sp.n. (Insecta: Neuroptera) are described based on a single specimen from the Yixian Formation (Liaoning Province, China; Early Cretaceous). The new taxon exhibits derived traits such as distally dilated antennae and well‐developed anterior Banksian line (known in Myrmeleontidae), but also genuine plesiomorphies (at the level of Myrmeleontiformia), such as the divergence of a distinct CuA1 stem from MP2 + CuA1 (forewing), and a basal origin of MA (diverging from RP + MA; both wing pairs). This combination is unique among the ‘Palaeoleontidae’, a group better considered as a paraphyletic assemblage of various stem‐Myrmeleontiformia. The wing morphology of the new species is considered in the light of a survey of wing venation topological homologies (and implied transformations) among several Neuroptera families. The survey includes a revision of the holotype of Leptolingia jurassica Ren (Grammolingiidae; Jiulongshan Formation, Daohugou locality, Inner Mongolia Autonomous Region, China; middle Jurassic). The forewing morphology of Guyiling jianbonigen. et sp.n. demonstrates that the fusion of MP2 with CuA, and the differentiation of CuA into two distinct main stems (namely CuA1 and CuA2) are traits shared with Myrmeleontidae and Ascalaphidae (and possibly Nemopteridae). However, the survey also demonstrates that a fusion of MP2 with CuA occurred repeatedly among Neuropterida, although by means of various modalities (namely translocation vs regular fusion). The ‘pectinate fusion’ of CuA(1) with MP2 [i.e. CuA1 has no distinct stem and emits successive branches from MP2 + CuA(1) partim] is a further step in this fusion, and occurred repeatedly as well (at least in the hind wings of Osmylidae and Nymphidae, and both fore‐ and hindwings of a sub‐group of Myrmeleontiformia including Myrmeleontidae and Ascalaphidae, and possibly Nemopteridae). It is anticipated that the current contribution will constitute useful background information for further studies, focusing on particular transformation cases, ideally including a documentation of intraspecific variation.
Phylogeny of psychodid subfamilies (Diptera: Psychodidae) inferred from nuclear DNA sequences with a review of morphological evidence for relationships
Authors: CURLER GREGORY R. , MOULTON JOHN K.
Published: June 2012

Psychodidae is a diverse family of flies with approximately 3000 described species in six subfamilies, including Phlebotominae vectors of human disease. Psychodidae has been the subject of few phylogenetic investigations and development of a stable classification has been hampered by poor understanding of the morphology of larvae, pupae and adults. Specimens were collected, and we analysed DNA sequence data from two nuclear genes for one or more representatives of all subfamilies. The subfamilies with multiple representatives included were resolved as monophyletic with good support. Placement of Horaiellinae, Sycoracinae and Trichomyiinae remains unclear, whereas Bruchomyiinae is hypothesized as the sister group to (Phlebotominae + Psychodinae). Representatives of some psychodine tribes were resolved in agreement with previous hypotheses. Relationships among and within subfamilies are discussed, and morphological characters supporting these relationships are reviewed. One compelling synapomorphy of the male genitalia supporting a relationship between Phlebotominae and Psychodinae is the presence of articulated surstyli with apical retinacula. Only cerci are present and sometimes developed into clasping structures in males of other subfamilies.
Molecular evidence of cycad seed predation by immature Aulacoscelidinae (Coleoptera: Orsodacnidae)
Authors: PRADO ALBERTO , MCKENNA DUANE D. , WINDSOR DONALD
Published: June 2012

Adult beetles in the small subfamily Aulacoscelidinae (superfamily Chrysomeloidea) are known to feed on the foliage and juices of New World cycads (Order Cycadales; family Zamiaceae), but the habits of larvae have long remained a mystery. We provide the first direct evidence that Aulacoscelidinae larvae feed on and develop within the megagametophyte of the Mesoamerican cycad,Dioon merolae(Zamiaceae). Phylogenetic analyses based on partial DNA sequences from 3 genes recover a cycad seed‐feeding larva proposed to belong to Aulacoscelidinae. These observations reveal a more intimate feeding relationship between Aulacoscelidinae and their New World cycad host plants than was previously recognized. Further, adult Aulacoscelidinae have long been noted to resemble Jurassic fossil chrysomeloids in the extinct subfamily Protoscelidinae. The molecular, morphological, ecological and fossil data reported herein are broadly compatible with an early association between Aulacoscelidinae and their gymnosperm hosts.
Vacuolar membrane transporters OsVIT1 and OsVIT2 modulate iron translocation between flag leaves and seeds in rice
Authors: Zhang Yu , Xu Yong‐Han , Yi Hong‐Yin , Gong Ji‐Ming
Published: June 2012

The plant vacuole is an important organelle for storing excess iron (Fe), though its contribution to increasing the Fe content in staple foods remains largely unexplored. In this study we report the isolation and functional characterization of two rice genes OsVIT1 and OsVIT2, orthologs of the Arabidopsis VIT1. Transient expression of OsVIT1:EGFP and OsVIT2:EGFP protein fusions revealed that OsVIT1 and OsVIT2 are localized to the vacuolar membrane. Ectopic expression of OsVIT1 and OsVIT2 partially rescued the Fe2+‐ and Zn2+‐sensitive phenotypes in yeast mutant Δccc1 and Δzrc1, and further increased vacuolar Fe2+, Zn2+ and Mn2+ accumulation. These data together suggest that OsVIT1 and OsVIT2 function to transport Fe2+, Zn2+ and Mn2+ across the tonoplast into vacuoles in yeast. In rice, OsVIT1 and OsVIT2 are highly expressed in flag leaf blade and sheath, respectively, and in contrast to OsVIT1, OsVIT2 is highly responsive to Fe treatments. Interestingly, functional disruption of OsVIT1 and OsVIT2 leads to increased Fe/Zn accumulation in rice seeds and a corresponding decrease in the source organ flag leaves, indicating an enhanced Fe/Zn translocation between source and sink organs, which might represent a novel strategy to biofortify Fe/Zn in staple foods.
A review of topical therapy for skin infections with bacteria and yeast
Authors: Mueller Ralf S. , Bergvall Kerstin , Bensignor Emmanuel , Bond Ross
Published: June 2012

Background – Cutaneous infections with bacteria and yeasts are common in small animal practice. Treatment with systemic antibiotics or antifungal agents may not be ideal, because of the increasing development of multiresistant organisms, the cost and the possible adverse effects. Topical antimicrobials may be used as adjunctive therapy to systemic treatment or as sole therapy instead of systemic treatment.

Objective – This literature review evaluated studies on topical antimicrobial treatment of skin infections.

Methods – In vitroandin vivostudies evaluating topical antimicrobial agents were identified using a number of electronic and manual searches of textbooks and articles. Studies were evaluated, and the evidence for or against the use of the topical agents was extracted.

Results – There is good evidence for the efficacy of chlorhexidine and, to a lesser degree, benzoyl peroxide in canine bacterial skin infections. There is limited evidence for the efficacy of silver sulfadiazine and medical honey against bacterial skin infections in the dog, and for the efficacy of hydrogen peroxide and stannous fluoride in the horse. Good evidence supports the use of a combination of chlorhexidine and miconazole in dogs with cutaneousMalasseziainfections. There is insufficient evidence to recommend any other topical therapy for use in cutaneous infections.

Conclusions and clinical importance – Although many antimicrobial topicals are marketed in veterinary dermatology, the efficacy has been reported for only a minority of agents. Randomized controlled trials evaluating various topical treatments are therefore urgently needed.
Effects of breed and dietary nutrient density on the growth performance, blood metabolite, and genes expression of target of rapamycin (TOR) signalling pathway of female broiler chickens
Authors: Wang X.‐q. , Jiang W. , Tan H.‐z. , Zhang D.‐x. , Zhang H.‐j. , Wei S. , Yan H.‐c.
Published: June 2012

This study was conducted to compare the effects of exchanged diets with identical energy level on characteristics of slow‐growing (WENs Yellow‐Feathered Chicken, WYFC) and fast‐growing (White Recessive Rock Chicken, WRRC) female chickens. A total of 1450 WYFC and 1150 WRRC 1‐day‐old female hatchlings were used. A high‐nutrient‐density (HND) diet and a low‐nutrient‐density (LND) diet were formulated for three phases. A completely randomized experimental design with a 2 × 2 factorial arrangement (diet and breed), each with five replicates of 145 and 115 birds, was applied. The results showed that WRRC had a higher body weight (BW), average daily feed intake and average daily gain than WYFC throughout the experiment (p < 0.05). WYFC that were provided with HND groups had a higher BW only in the starter and grower phases, whereas WRRC had a higher BW in the HND group than in LND groups throughout the experiment. The feed:gain ratio and protein efficiency ratio (PER) were better for WRRC in the starter and grower phases; however, these ratios were better for WYFC in the finisher period. The LND groups had a higher PER throughout the experiment for both breeds (p < 0.05). The breast and leg muscle weights were higher for WRRC compared with WYFC during the grower and finisher phases (p < 0.05). WRRC had a lower liver index but higher serum UA and alkaline phosphatase (ALP) concentrations than WYFC (p < 0.05). No diet effect was observed on organ indices, muscle yields or blood responses. The gene expressions of Rheb, TOR, S6K1 and 4E‐BP1 in gastrocnemius muscle were the highest in the WYFC‐LND groups at 63 and 105 days (p < 0.05). These findings suggested that different genotypes respond differently to changes in dietary nutrient density and that lower‐nutrient‐density diets are optimal for the long‐term housing of broiler chickens.
Contracted bladder developing after prostate brachytherapy
Authors: Yamada Yuta , Minowada Shigeru , Aruga Takashi , Homma Yukio
Published: June 2012

This report describes an extremely rare case of severely contracted bladder developing after prostate brachytherapy. In April 2001, a 76‐year‐old man initially presented to our hospital for weak urinary stream. The patient was diagnosed with and treated for benign prostatic hyperplasia. During follow up, prostate‐specific antigen level was elevated. In November 2005, the patient underwent transrectal prostate biopsy. Pathology showed adenocarcinoma, Gleason score 3 + 4 = 7. The patient was diagnosed with stage cT1cN0M0 prostate cancer. In January 2006, he underwent brachytherapy for prostate cancer. The procedure of brachytherapy was uneventful and the patient was discharged without any problems. Four months after the implant, the patient was admitted to our hospital for deterioration of kidney function as a result of a contracted bladder. Urinary culture of tuberculosis was negative and urinary cytology was class II. A urethral catheter was indwelled and the patient has been followed every month for catheter replacement. Bladder capacity is now less than 5 mL.
Dexamethasone versus ondansetron in combination with dexamethasone for the prophylaxis of postoperative vomiting in pediatric outpatients: a double‐blind, randomized, placebo‐controlled clinical trial
Authors: de Orange Flávia A. , Marques Jaime , Flores Marília , Borges Paulo S. G. N.
Published: June 2012

Objectives:  To determine the frequency of postoperative vomiting (POV) in children submitted to outpatient surgery and to compare the efficacy of antiemetic drugs in preventing this complication.

Background:  Nausea and vomiting are common in the immediate postoperative period following anesthetic and surgical procedures. Compared to adults, pediatric patients are more likely to develop postoperative nausea and vomiting, the incidence of which ranges from 8.9% to 42%.

Methods:  This double‐blind, randomized, placebo‐controlled clinical trial included 129 children. The participants were randomized into three prophylactic treatment groups: dexamethasone (n = 43), ondansetron in combination with dexamethasone (n = 44), and placebo (n = 42). The variables studied were the frequency of POV and the incidence of vomiting after the patient had been discharged from hospital, the need for antiemetic rescue therapy in the postanesthesia care unit (PACU), need for hospitalization, and the time the patient remained in the PACU. A significance level of 5% was adopted.

Results:  Postoperative vomiting occurred in 12.4% of the children, with no statistically significant difference between the groups: 6.8% in the group receiving ondansetron combined with dexamethasone, 14.3% in the placebo group, and 14% in the group that received dexamethasone alone (P = 0.47). Furthermore, no significant difference was found between the groups with respect to the time the children remained in the PACU, and only five patients reported having vomited following discharge from hospital.

Conclusions:  The prophylactic use of antiemetic drugs failed to reduce the incidence of POV in pediatric outpatient surgery with a low emetic potential; therefore, routine prophylaxis may be unnecessary.
Cancer auditing – how accurate are your data?
Authors: Platell C. , Penter C.
Published: June 2012

Aim  Human involvement in the collection and entering of information into a database leads to a degree of error. The aim of this study was to assess the concordance between two individuals blinded from each other who independently collected information on the same set of patients and entered it into a colorectal neoplasia database.

Method  A colorectal research nurse and a surgeon independently maintained an electronic database on all new patients admitted with colorectal neoplasia under the surgeon over a 5‐year period. Twenty‐three key endpoints were selected from the database in order to determine the agreement between the two observers. The κ statistic (for nominal and ordinal data) and the concordance correlation coefficient (for interval data) were used to determine the level of agreement between the two data sets.

Results  Both observers recorded 432 new referrals during this period. There was only complete concordance between the two databases with respect to the number of new patients and returns to theatre within 30 days. Nonetheless, there was almost perfect concordance between the two data sets for a majority of the endpoints. The most important areas of variance were in the length of stay (κ = 0.78), the American Society of Anesthesiology grade (κ = 0.41), emergency surgery (κ = 0.36), nodal staging (κ = 0.54) and time to recurrence (κ = 0.77).

Conclusion  This study highlights a number of important areas of data inaccuracy in a prospective colorectal database. The inaccuracies were due to observer bias, issues of data interpretation, or just difficulty in collecting the information accurately.
Computing Voronoi Treemaps: Faster, Simpler, and Resolution‐independent
Authors: Nocaj Arlind , Brandes Ulrik
Published: June 2012

Voronoi treemaps represent hierarchies as nested polygons. We here show that, contrary to the apparent popular belief, utilization of an algorithm for weighted Voronoi diagrams is not only feasible, but also more efficient than previous low‐resolution approximations, even when the latter are implemented on graphics hardware. More precisely, we propose an instantiation of Lloyd's method for centroidal Voronoi diagrams with Aurenhammer's algorithm for power diagrams that yields an algorithm running in 𝒪(n log n) rather than Ω(n2) time per iteration, with n the number of sites. We describe its implementation and present evidence that it is faster also in practice.
Multi‐layer illustrative dense flow visualization
Authors: Carnecky R. , Schindler B. , Fuchs R. , Peikert R.
Published: June 2012

We present a dense visualization of vector fields on multi‐layered surfaces. The method is based on the illustration buffer, which provides a screen space representation of the surface, where each pixel stores a list of all surface layers. This representation is implemented on the GPU using shaders and leads to a fast output sensitive technique. In our approach, we first use procedural noise to create an initial spot pattern on the surface that has both an almost constant screen space frequency and is view independent. Then, we perform anisotropic diffusion simultaneously on all surface layers using a discretization scheme that maintains second order convergence while only accessing the four neighboring pixels. Finally, we enhance this result with illustrative techniques and composite the final image. Our method works with time‐evolving surfaces, time‐dependent vector fields, and moving cameras. We apply our method to CFD data sets from engineering and astronomy as well as synthetic velocity fields.
Illustrative Membrane Clipping
Authors: Birkeland Å. , Bruckner S. , Brambilla A. , Viola I.
Published: June 2012

Clipping is a fast, common technique for resolving occlusions. It only requires simple interaction, is easily understandable, and thus has been very popular for volume exploration. However, a drawback of clipping is that the technique indiscriminately cuts through features. Illustrators, for example, consider the structures in the vicinity of the cut when visualizing complex spatial data and make sure that smaller structures near the clipping plane are kept in the image and not cut into fragments. In this paper we present a new technique, which combines the simple clipping interaction with automated selective feature preservation using an elastic membrane. In order to prevent cutting objects near the clipping plane, the deformable membrane uses underlying data properties to adjust itself to salient structures. To achieve this behaviour, we translate data attributes into a potential field which acts on the membrane, thus moving the problem of deformation into the soft‐body dynamics domain. This allows us to exploit existing GPU‐based physics libraries which achieve interactive frame rates. For manual adjustment, the user can insert additional potential fields, as well as pinning the membrane to interesting areas. We demonstrate that our method can act as a flexible and non‐invasive replacement of traditional clipping planes.
Travel‐Route‐Centered Metro Map Layout and Annotation
Authors: Wu Hsiang‐Yun , Takahashi Shigeo , Lin Chun‐Cheng , Yen Hsu‐Chun
Published: June 2012

When providing travel guides for a specific route in a metro network, we often place the route around the center of the map and annotate stations on the route with thumbnail photographs. Nonetheless, existing methods do not offer an effective means of customizing the network layout in order to accommodate such large annotation labels while preserving its planar embedding. This paper presents a new approach for designing the metro map layout in order to annotate stations on a specific travel route with large annotation labels. Our idea is to elongate the travel route to be straight along the centerline of the map so that we can systematically annotate such stations with external labels. This is accomplished by extending the conventional mixed‐integer programming technique for computing octilinear layouts where orientations inherent to the metro line segments are plausibly rearranged. The stations are then connected with external labels through leaders while minimizing intersections with metro lines for enhancing visual clarity. We present several design examples of metro maps and user studies to demonstrate that the proposed aesthetic criteria successfully direct viewers’ attention to specific travel routes.
The World's Languages Explorer: Visual Analysis of Language Features in Genealogical and Areal Contexts
Authors: Rohrdantz Christian , Hund Michael , Mayer Thomas , Wälchli Bernhard , Keim Daniel A.
Published: June 2012

This paper presents a novel Visual Analytics approach that helps linguistic researchers to explore the world's languages with respect to several important tasks: (1) The comparison of manually and automatically extracted language features across languages and within the context of language genealogy, (2) the exploration of interrelations among several of such features as well as their homogeneity and heterogeneity within subtrees of the language genealogy, and (3) the exploration of genealogical and areal influences on the features. We introduce theWorld'sLanguagesExplorer, which provides the required functionalities in one single Visual Analytics environment. Contributions are made for different parts of the system: We introduce an extended Sunburst visualization whose so‐called feature‐rings allow for a cross‐comparison of a large number of features at once, within the hierarchical context of the language genealogy. We suggest a mapping of homogeneity measures to all levels of the hierarchy. In addition, we suggest an integration of information from the areal data space into the hierarchical data space. With our approach we bring Visual Analytics research to a new application field, namely Historical Comparative Linguistics, and Linguistic and Areal Typology. Finally, we provide evidence of the good performance of our system in this area through two application case studies conducted by domain experts.
Magnetic Flux Topology of 2D Point Dipoles
Authors: Bachthaler Sven , Sadlo Filip , Weeber Rudolf , Kantorovich Sofia , Holm Christian , Weiskopf Daniel
Published: June 2012

Magnetic fields exhibit higher‐order, nonlinear singularities in the form of point‐dipole singularities. In addition, due to absence of divergence, they feature only a subset of invariant structures from traditional vector field topology. For magnetic fields of sets of point dipoles—widely present in physics and often used as an approximation—we present a technique revealing the topology of magnetic flux. The flux topology is identified with areas covered by field lines that directly connect pairs of dipoles. We introduce the dipole connectrix as a reduced one‐manifold representation of those areas. The set of connectrices serves as our concise visualization of the global structure of magnetic flux. In addition, the quantitative values of flux are displayed by the thickness of the connectrices. We evaluate our technique for simulations of ferroparticle monolayers and magnetic gels.
Parallel Computation of 3D Morse‐Smale Complexes
Authors: Shivashankar Nithin , Natarajan Vijay
Published: June 2012

The Morse‐Smale complex is a topological structure that captures the behavior of the gradient of a scalar function on a manifold. This paper discusses scalable techniques to compute the Morse‐Smale complex of scalar functions defined on large three‐dimensional structured grids. Computing the Morse‐Smale complex of three‐dimensional domains is challenging as compared to two‐dimensional domains because of the non‐trivial structure introduced by the two types of saddle criticalities. We present a parallel shared‐memory algorithm to compute the Morse‐Smale complex based on Forman's discrete Morse theory. The algorithm achieves scalability via synergistic use of the CPU and the GPU. We first prove that the discrete gradient on the domain can be computed independently for each cell and hence can be implemented on the GPU. Second, we describe a two‐step graph traversal algorithm to compute the 1‐saddle‐2‐saddle connections efficiently and in parallel on the CPU. Simultaneously, the extremasaddle connections are computed using a tree traversal algorithm on the GPU.
Using Signposts for Navigation in Large Graphs
Authors: May T. , Steiger M. , Davey J. , Kohlhammer J.
Published: June 2012

In this paper we present a new Focus & Context technique for the exploration of large, abstract graphs. Most Focus & Context techniques present context in a visual way. In contrast, our technique uses a symbolic representation: while the focus is a set of visible nodes, labelled signposts provide cues for the context — off‐screen regions of the graph — and indicate the direction of the shortest path linking the visible nodes to these regions. We show how the regions are defined and how they are selected dynamically, depending on the visible nodes. To define the set of visible nodes we use an approach developed by van Ham and Perer that dynamically extracts a subgraph based on an initial focal node and a degree‐of‐interest function. This approach is extended to support multiple focal nodes. With the symbolic visualization, potentially interesting regions of a graph may be represented with a very small visual footprint. We conclude the paper with an initial user study to evaluate the effectiveness of the signposts for navigation tasks.
Comparative Evaluation of an Interactive Time‐Series Visualization that Combines Quantitative Data with Qualitative Abstractions
Authors: Aigner W. , Rind A. , Hoffmann S.
Published: June 2012

In many application areas, analysts have to make sense of large volumes of multivariate time‐series data. Explorative analysis of this kind of data is often difficult and overwhelming at the level of raw data. Temporal data abstraction reduces data complexity by deriving qualitative statements that reflect domain‐specific key characteristics. Visual representations of abstractions and raw data together with appropriate interaction methods can support analysts in making their data easier to understand. Such a visualization technique that applies smooth semantic zooming has been developed in the context of patient data analysis. However, no empirical evidence on its effectiveness and efficiency is available. In this paper, we aim to fill this gap by reporting on a controlled experiment that compares this technique with another visualization method used in the well‐known KNAVE‐II framework. Both methods integrate quantitative data with qualitative abstractions whereas the first one uses a composite representation with color‐coding to display the qualitative data and spatial position coding for the quantitative data. The second technique uses juxtaposed representations for quantitative and qualitative data with spatial position coding for both. Results show that the test persons using the composite representation were generally faster, particularly for more complex tasks that involve quantitative values as well as qualitative abstractions.
A Qualitative Study on the Exploration of Temporal Changes in Flow Maps with Animation and Small‐Multiples
Authors: Boyandin Ilya , Bertini Enrico , Lalanne Denis
Published: June 2012

We present a qualitative user study analyzing findings made while exploring changes over time in spatial interactions. We analyzed findings made by the study participants with flow maps, one of the most popular representations of spatial interactions, using animation and small‐multiples as two alternative ways of representing temporal changes. Our goal was not to measure the subjects’ performance with the two views, but to find out whether there are qualitative differences between the types of findings users make with these two representations. To achieve this goal we performed a deep analysis of the collected findings, the interaction logs, and the subjective feedback from the users. We observed that with animation the subjects tended to make more findings concerning geographically local events and changes between subsequent years. With small‐multiples more findings concerning longer time periods were made. Besides, our results suggest that switching from one view to the other might lead to an increase in the numbers of findings of specific types made by the subjects which can be beneficial for certain tasks.
Conceptualizing Visual Uncertainty in Parallel Coordinates
Authors: Dasgupta Aritra , Chen Min , Kosara Robert
Published: June 2012

Uncertainty is an intrinsic part of any visual representation in visualization, no matter how precise the input data. Existing research on uncertainty in visualization mainly focuses on depicting data‐space uncertainty in a visual form. Uncertainty is thus often seen as a problem to deal with, in the data, and something to be avoided if possible. In this paper, we highlight the need for analyzing visual uncertainty in order to design more effective visual representations. We study various forms of uncertainty in the visual representation of parallel coordinates and propose a taxonomy for categorizing them. By building a taxonomy, we aim to identify different sources of uncertainty in the screen space and relate them to different effects of uncertainty upon the user. We examine the literature on parallel coordinates and apply our taxonomy to categorize various techniques for reducing uncertainty. In addition, we consider uncertainty from a different perspective by identifying cases where increasing certain forms of uncertainty may even be useful, with respect to task, data type and analysis scenario. This work suggests that uncertainty is a feature that can be both useful and problematic in visualization, and it is beneficial to augment an information visualization pipeline with a facility for visual uncertainty analysis.
Visualization of Global Correlation Structures in Uncertain 2D Scalar Fields
Authors: Pfaffelmoser Tobias , Westermann Rüdiger
Published: June 2012

Visualizing correlations, i.e., the tendency of uncertain data values at different spatial positions to change contrarily or according to each other, allows inferring on the possible variations of structures in the data. Visualizing global correlation structures, however, is extremely challenging, since it is not clear how the visualization of complicated long‐range dependencies can be integrated into standard visualizations of spatial data. Furthermore, storing correlation information imposes a memory requirement that is quadratic in the number of spatial sample positions. This paper presents a novel approach for visualizing both positive and inverse global correlation structures in uncertain 2D scalar fields, where the uncertainty is modeled via a multivariate Gaussian distribution. We introduce a new measure for the degree of dependency of a random variable on its local and global surroundings, and we propose a spatial clustering approach based on this measure to classify regions of a particular correlation strength. The clustering performs a correlation filtering, which results in a representation that is only linear in the number of spatial sample points. Via cluster coloring the correlation information can be embedded into visualizations of other statistical quantities, such as the mean and the standard deviation. We finally propose a hierarchical cluster subdivision scheme to further allow for the simultaneous visualization of local and global correlations.
Vortex Analysis in Uncertain Vector Fields
Authors: Otto Mathias , Theisel Holger
Published: June 2012

We present an approach to extract and visualize vortex structures in uncertain vector fields. For this, we generalize the concepts of the most common vortex detectors to uncertain vector fields, namely the λ2‐criterion, Q‐criterion, and the concept of parallel vectors at the example of the method by Sujudi and Haimes. All these methods base on the computation of derivatives of the uncertain vector field which are uncertain fields as well. Since they generally cannot be computed in a closed form, we provide a Monte Carlo algorithm to compute the respective probability distributions. Based on this, uncertain versions of vortex regions and core structures are introduced. We present results of our approach on three real world data sets in order to give a proof of concept.
Probabilistic Local Features in Uncertain Vector Fields with Spatial Correlation
Authors: Petz Christoph , Pöthkow Kai , Hege Hans‐Christian
Published: June 2012

In this paper methods for extraction of local features in crisp vector fields are extended to uncertain fields. While in a crisp field local features are either present or absent at some location, in an uncertain field they are present with some probability. We model sampled uncertain vector fields by discrete Gaussian random fields with empirically estimated spatial correlations. The variability of the random fields in a spatial neighborhood is characterized by marginal distributions. Probabilities for the presence of local features are formulated in terms of low‐dimensional integrals over such marginal distributions. Specifically, we define probabilistic equivalents for critical points and vortex cores. The probabilities are computed by Monte Carlo integration. For identification of critical points and cores of swirling motion we employ the Poincaré index and the criterion by Sujudi and Haimes. In contrast to previous global methods we take a local perspective and directly extract features in divergence‐free fields as well. The method is able to detect saddle points in a straight forward way and works on various grid types. It is demonstrated by applying it to simulated unsteady flows of biofluid and climate dynamics.
Employing 2D Projections for Fast Visual Exploration of Large Fiber Tracking Data
Authors: Poco Jorge , Eler Danilo M. , Paulovich Fernando V. , Minghim Rosane
Published: June 2012

Fiber tracts detection is an increasingly common technology for diagnosis and also understanding of brain function. Although tools for tracing and presenting brain fibers are advanced, it is still difficult for physicians or students to explore the dataset in 3D due to their intricate topology. In this work we present a visual exploration approach for fiber tracts data aimed at supporting exploration of such data. The work employs a local, precise and fast 2D multidimensional projection technique that allows a large number of fibers to be handled simultaneously and to select groups of bundled fibers for further exploration. In this approach, a DTI feature dataset, including curvature as well as spatial features, is projected on a 2D or 3D view. By handling groups formed in this view, exploration is linked to corresponding brain fibers in object space. The link exists in both directions and fibers selected in object space are also mapped to feature space. Our approach also allows users to modify the projection, controlling and improving, if necessary, the definition of groups of fibers for small and large datasets, due to the local nature of the projection. Compared to other related work, the method presented here is faster for creating visual representations, making it possible to explore complete sets of fibers tracts up to 250K fibers, which was not possible previously. Additionally, the ability to change configuration of the feature space representation adds a high degree of flexibility to the process.
Biopsy Planner – Visual Analysis for Needle Pathway Planning in Deep Seated Brain Tumor Biopsy
Authors: Herghelegiu P. C. , Manta V. , Perin R. , Bruckner S. , Gröller E.
Published: June 2012

Biopsies involve taking samples from living tissue using a biopsy needle. In current clinical practice they are a first mandatory step before any further medical actions are planned. Performing a biopsy on a deep seated brain tumor requires considerable time for establishing and validating the desired biopsy needle pathway to avoid damage. In this paper, we present a system for the visualization, analysis, and validation of biopsy needle pathways. Our system uses a multi‐level approach for identifying stable needle placements which minimize the risk of hitting blood vessels. This is one of the major dangers in this type of intervention. Our approach helps in identifying and visualizing the point on the pathway that is closest to a surrounding blood vessel, requiring a closer inspection by the neurosurgeon. An evaluation by medical experts is performed to demonstrate the utility of our system.
Nearly Recurrent Components in 3D Piecewise Constant Vector Fields
Authors: Szymczak Andrzej , Brunhart‐Lupo Nicholas
Published: June 2012

We present an algorithm for computing nearly recurrent components, that represent areas of close to circulating or stagnant flow, for 3D piecewise constant (PC) vector fields defined on regular grids. Using a number of analytical and simulated data sets, we demonstrate that nearly recurrent components can provide interesting insight into the topological structure of 3D vector fields.

Our approach is based on prior work on Morse decompositions for PC vector fields on surfaces and extends concepts previously developed with this goal in mind to the case of 3D vector fields defined on regular grids. Our contributions include a description of trajectories of 3D piecewise constant vector fields and an extension of the transition graph, a finite directed graph that represents all trajectories, to the 3D case. Nearly recurrent components are defined by strongly connected components of the transition graph.
Interface Exchange as an Indicator for Eddy Heat Transport
Authors: Williams S. , Petersen M. , Hecht M. , Maltrud M. , Patchett J. , Ahrens J. , Hamann B.
Published: June 2012

The ocean contains many large‐scale, long‐lived vortices, called mesoscale eddies, that are believed to have a role in the transport and redistribution of salt, heat, and nutrients throughout the ocean. Determining this role, however, has proven to be a challenge, since the mechanics of eddies are only partly understood; a standard definition for these ocean eddies does not exist and, therefore, scientifically meaningful, robust methods for eddy extraction, characterization, tracking and visualization remain a challenge. To shed light on the nature and potential roles of eddies, we extend our previous work on eddy identification and tracking to construct a new metric to characterize the transfer of water into and out of eddies across their boundary, and produce several visualizations of this new metric to provide clues about the role eddies play in the global ocean.
Rolled‐out Wordles: A Heuristic Method for Overlap Removal of 2D Data Representatives
Authors: Strobelt H. , Spicker M. , Stoffel A. , Keim D. , Deussen O.
Published: June 2012

When representing 2D data points with spacious objects such as labels, overlap can occur. We present a simple algorithm which modifies the (Mani‐) Wordle idea with scan‐line based techniques to allow a better placement. We give an introduction to common placement techniques from different fields and compare our method to these techniques w.r.t. euclidean displacement, changes in orthogonal ordering as well as shape and size preservation. Especially in dense scenarios our method preserves the overall shape better than known techniques and allows a good trade‐off between the other measures. Applications on real world data are given and discussed.
iVisClustering: An Interactive Visual Document Clustering via Topic Modeling
Authors: Lee Hanseung , Kihm Jaeyeon , Choo Jaegul , Stasko John , Park Haesun
Published: June 2012

Clustering plays an important role in many large‐scale data analyses providing users with an overall understanding of their data. Nonetheless, clustering is not an easy task due to noisy features and outliers existing in the data, and thus the clustering results obtained from automatic algorithms often do not make clear sense. To remedy this problem, automatic clustering should be complemented with interactive visualization strategies. This paper proposes an interactive visual analytics system for document clustering, called iVisClustering, based on a widely‐used topic modeling method, latent Dirichlet allocation (LDA). iVisClustering provides a summary of each cluster in terms of its most representative keywords and visualizes soft clustering results in parallel coordinates. The main view of the system provides a 2D plot that visualizes cluster similarities and the relation among data items with a graph‐based representation. iVisClustering provides several other views, which contain useful interaction methods. With help of these visualization modules, we can interactively refine the clustering results in various ways. Keywords can be adjusted so that they characterize each cluster better. In addition, our system can filter out noisy data and re‐cluster the data accordingly. Cluster hierarchy can be constructed using a tree structure and for this purpose, the system supports cluster‐level interactions such as sub‐clustering, removing unimportant clusters, merging the clusters that have similar meanings, and moving certain clusters to any other node in the tree structure. Furthermore, the system provides document‐level interactions such as moving mis‐clustered documents to another cluster and removing useless documents. Finally, we present how interactive clustering is performed via iVisClustering by using real‐world document data sets.
StratomeX: Visual Analysis of Large‐Scale Heterogeneous Genomics Data for Cancer Subtype Characterization
Authors: Lex A. , Streit M. , Schulz H.‐J. , Partl C. , Schmalstieg D. , Park P.J. , Gehlenborg N.
Published: June 2012

Identification and characterization of cancer subtypes are important areas of research that are based on the integrated analysis of multiple heterogeneous genomics datasets. Since there are no tools supporting this process, much of this work is done using ad‐hoc scripts and static plots, which is inefficient and limits visual exploration of the data. To address this, we have developed StratomeX, an integrative visualization tool that allows investigators to explore the relationships of candidate subtypes across multiple genomic data types such as gene expression, DNA methylation, or copy number data. StratomeX represents datasets as columns and subtypes as bricks in these columns. Ribbons between the columns connect bricks to show subtype relationships across datasets. Drill‐down features enable detailed exploration. StratomeX provides insights into the functional and clinical implications of candidate subtypes by employing small multiples, which allow investigators to assess the effect of subtypes on molecular pathways or outcomes such as patient survival. As the configuration of viewing parameters in such a multi‐dataset, multi‐view scenario is complex, we propose a meta visualization and configuration interface for dataset dependencies and data‐view relationships. StratomeX is developed in close collaboration with domain experts. We describe case studies that illustrate how investigators used the tool to explore subtypes in large datasets and demonstrate how they efficiently replicated findings from the literature and gained new insights into the data.
Porosity Maps – Interactive Exploration and Visual Analysis of Porosity in Carbon Fiber Reinforced Polymers
Authors: Reh A. , Plank B. , Kastner J. , Gröller E. , Heinzl C.
Published: June 2012

In this work a novel method for the characterization of porosity in carbon fiber reinforced polymers (CFRP) is presented. A visualization pipeline for the interactive exploration and visual analysis of CFRP specimens is developed to enhance the evaluation workflow for non‐destructive testing (NDT) practitioners based on specified tasks. Besides quantitative porosity determination and the calculation of local pore properties, i.e., volume, surface, dimensions and shape factors, we employ a drill‐down approach to explore pores in a CFRP specimen. We introduce Porosity Maps (PM), to allow for a fast porosity evaluation of the specimen. Pores are filtered in two stages. First a region of interest is selected in the porosity maps. Second, pores are filtered with parallel coordinates according to their local properties. Furthermore a histogram‐based best‐viewpoint widget was implemented to visualize the quality of viewpoints on a sphere. The advantages of our approach are demonstrated using real world CFRP specimens. We are able to show that our visualization‐driven approach leads to a better evaluation of CFRP components than existing reference methods.