190 research outputs found

    Repeated Web Page Visits and the Scanpath Theory: A Recurrent Pattern Detection Approach

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    This paper investigates the eye movement sequences of users visiting web pages repeatedly. We are interested in potential habituation due to repeated exposure. The scanpath theory posits that every person learns an idiosyncratic gaze sequence on first exposure to a stimulus and re-applies it on subsequent exposures. Josephson and Holmes (2002) tested the applicability of this hypothesis to web page revisitation but results were inconclusive. With a recurrent temporal pattern detection technique, we examine additional aspects and expose scanpaths. Results do not suggest direct applicability of the scanpath theory. While repetitive scan patterns occurred and were individually distinctive, their occurrence was variable, there were often several different patterns per person, and patterns were not primarily formed on the first exposure. However, extensive patterning occurred for some participants yet not for others which deserves further study into its determinants

    User-centered design of a dynamic-autonomy remote interaction concept for manipulation-capable robots to assist elderly people in the home

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    In this article, we describe the development of a human-robot interaction concept for service robots to assist elderly people in the home with physical tasks. Our approach is based on the insight that robots are not yet able to handle all tasks autonomously with sufficient reliability in the complex and heterogeneous environments of private homes. We therefore employ remote human operators to assist on tasks a robot cannot handle completely autonomously. Our development methodology was user-centric and iterative, with six user studies carried out at various stages involving a total of 241 participants. The concept is under implementation on the Care-O-bot 3 robotic platform. The main contributions of this article are (1) the results of a survey in form of a ranking of the demands of elderly people and informal caregivers for a range of 25 robot services, (2) the results of an ethnography investigating the suitability of emergency teleassistance and telemedical centers for incorporating robotic teleassistance, and (3) a user-validated human-robot interaction concept with three user roles and corresponding three user interfaces designed as a solution to the problem of engineering reliable service robots for home environments

    Treatment of posttraumatic and focal osteoarthritic cartilage defects of the knee with autologous polymer-based three-dimensional chondrocyte grafts: 2-year clinical results

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    Autologous chondrocyte implantation (ACI) is an effective clinical procedure for the regeneration of articular cartilage defects. BioSeedÂź-C is a second-generation ACI tissue engineering cartilage graft that is based on autologous chondrocytes embedded in a three-dimensional bioresorbable two-component gel-polymer scaffold. In the present prospective study, we evaluated the short-term to mid-term efficacy of BioSeed-C for the arthrotomic and arthroscopic treatment of posttraumatic and degenerative cartilage defects in a group of patients suffering from chronic posttraumatic and/or degenerative cartilage lesions of the knee. Clinical outcome was assessed in 40 patients with a 2-year clinical follow-up before implantation and at 3, 6, 12, and 24 months after implantation by using the modified Cincinnati Knee Rating System, the Lysholm score, the Knee injury and Osteoarthritis Outcome Score, and the current health assessment form (SF-36) of the International Knee Documentation Committee, as well as histological analysis of second-look biopsies. Significant improvement (p < 0.05) in the evaluated scores was observed at 1 and/or 2 years after implantation of BioSeed-C, and histological staining of the biopsies showed good integration of the graft and formation of a cartilaginous repair tissue. The Knee injury and Osteoarthritis Outcome Score showed significant improvement in the subclasses pain, other symptoms, and knee-related quality of life 2 years after implantation of BioSeed-C in focal osteoarthritic defects. The results suggest that implanting BioSeed-C is an effective treatment option for the regeneration of posttraumatic and/or osteoarthritic defects of the knee

    The globin gene family of the cephalochordate amphioxus: implications for chordate globin evolution

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    <p>Abstract</p> <p>Background</p> <p>The lancelet amphioxus (Cephalochordata) is a close relative of vertebrates and thus may enhance our understanding of vertebrate gene and genome evolution. In this context, the globins are one of the best studied models for gene family evolution. Previous biochemical studies have demonstrated the presence of an intracellular globin in notochord tissue and myotome of amphioxus, but the corresponding gene has not yet been identified. Genomic resources of <it>Branchiostoma floridae </it>now facilitate the identification, experimental confirmation and molecular evolutionary analysis of its globin gene repertoire.</p> <p>Results</p> <p>We show that <it>B. floridae </it>harbors at least fifteen paralogous globin genes, all of which reveal evidence of gene expression. The protein sequences of twelve globins display the conserved characteristics of a functional globin fold. In phylogenetic analyses, the amphioxus globin BflGb4 forms a common clade with vertebrate neuroglobins, indicating the presence of this nerve globin in cephalochordates. Orthology is corroborated by conserved syntenic linkage of <it>BflGb4 </it>and flanking genes. The kinetics of ligand binding of recombinantly expressed BflGb4 reveals that this globin is hexacoordinated with a high oxygen association rate, thus strongly resembling vertebrate neuroglobin. In addition, possible amphioxus orthologs of the vertebrate globin X lineage and of the myoglobin/cytoglobin/hemoglobin lineage can be identified, including one gene as a candidate for being expressed in notochord tissue. Genomic analyses identify conserved synteny between amphioxus globin-containing regions and the vertebrate <it>ÎČ-globin </it>locus, possibly arguing against a late transpositional origin of the <it>ÎČ-globin </it>cluster in vertebrates. Some amphioxus globin gene structures exhibit minisatellite-like tandem duplications of intron-exon boundaries ("mirages"), which may serve to explain the creation of novel intron positions within the globin genes.</p> <p>Conclusions</p> <p>The identification of putative orthologs of vertebrate globin variants in the <it>B. floridae </it>genome underlines the importance of cephalochordates for elucidating vertebrate genome evolution. The present study facilitates detailed functional studies of the amphioxus globins in order to trace conserved properties and specific adaptations of respiratory proteins at the base of chordate evolution.</p

    Corals of the genus Porites are a locally abundant component of the epibiont community on mangrove prop roots at Calabash Caye, Turneffe Atoll, Belize

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    Mangroves are generally regarded as inhospitable for corals, but recent reports suggest they provide ecological refuge for some species. We surveyed diverse mangrove habitats on Turneffe Atoll, Belize, documenting 127 colonies of Porites divaricata (Thin Finger Coral) along 1858 m of mangrove prop roots at Calabash Caye and a much more diverse coral assemblage at Crooked Creek. At Calabash, corals were highly clumped, and varied widely in size and morphology, including large well-arborized colonies, encrusting forms with few branches, and new recruits with no branches, suggesting an age-structuredpopulation exhibiting extensive morphological plasticity. The data described here contributeto an emerging picture of mangroves as potentially critical habitat for many Caribbeancoral species.Accepted manuscrip

    Coupling of disulfide bond and distal histidine dissociation in human ferrous cytoglobin regulates ligand binding

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    Earlier kinetics studies on cytoglobin did not assign functional properties to specific structural forms. Here, we used defined monomeric and dimeric forms and cysteine mutants to show that an intramolecular disulfide bond (C38-C83) alters the dissociation rate constant of the intrinsic histidine (H81) (∌1000 fold), thus controlling binding of extrinsic ligands. Through time-resolved spectra we have unequivocally assigned CO binding to hexa- and penta-coordinate forms and have made direct measurement of histidine rebinding following photolysis. We present a model that describes how the cysteine redox state of the monomer controls histidine dissociation rate constants and hence extrinsic ligand binding

    Results of a randomized trial of treatment modalities in patients with low or early-intermediate risk prostate cancer (PREFERE trial)

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    Purpose The optimal treatment for patients with low to early-intermediate risk prostate cancer (PCa) remains to be defned. The randomized PREFERE trial (DRKS00004405) aimed to assess noninferiority of active surveillance (AS), externalbeam radiotherapy (EBRT), or brachytherapy by permanent seed implantation (PSI) vs. radical prostatectomy (RP) for these patients. Methods PREFERE was planned to enroll 7600 patients. The primary endpoint was disease specifc survival. Patients with PCa stage≀cT2a, cN0/X, M0, PSA ≀10 ng/ml and Gleason-Score≀3+4 at reference pathology were eligible. Patients were allowed to exclude one or two of the four modalities, which yielded eleven combinations for randomization. Sixty-nine German study centers were engaged in PREFERE. Results Of 2251 patients prescreened between 2012 and 2016, 459 agreed to participate in PREFERE. Due to this poor accrual, the trial was stopped. In 345 patients reference pathology confrmed inclusion criteria. Sixty-nine men were assigned to RP, 53 to EBRT, 93 to PSI, and 130 to AS. Forty patients changed treatment shortly after randomization, 21 to AS. Fortyeight AS patients with follow-up received radical treatment. Median follow-up was 19 months. Five patients died, none due to PCa; 8 had biochemical progression after radical therapy. Treatment-related acute grade 3 toxicity was reported in 3 RP patients and 2 PSI patients. Conclusions In this prematurely closed trial, we observed an unexpected high rate of termination of AS and an increased toxicity related to PSI. Patients hesitated to be randomized in a multi-arm trial. The optimal treatment of low and earlyintermediate risk PCa remains unclear
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