Subsequent Video Analysis Research Articles

Standardized examinees: development of a new tool to evaluate factors influencing OSCE scores and to train examiners.

Introduction: The Objective Structured Clinical Examination (OSCE) is an established format for practical clinical assessments at most medical schools and discussion is underway in Germany to make it part of future state medical exams. Examiner behavior that influences assessment results is described. Erroneous assessments of student performance can result, for instance, from systematic leniency, inconsistent grading, halo effects, and even a lack of differentiation between the tasks to be performed over the entire grading scale. The aim of this study was to develop a quality assurance tool that can monitor factors influencing grading in a real OSCE and enable targeted training of examiners.Material, Methods and Students: Twelve students at the Medical Faculty of the University of Heidelberg were each trained to perform a defined task for a particular surgical OSCE station. Definitions were set and operationalized for an excellent and a borderline performance. In a simulated OSCE during the first part of the study, the standardized student performances were assessed and graded by different examiners three times in succession; video recordings were made. Quantitative and qualitative analysis of the videos was also undertaken by the study coordinator.In the second part of the study, the videos were used to investigate the examiners’ acceptance of standardized examinees and to analyze potential influences on scoring that stemmed from the examiners’ experience.Results: In the first part of the study, the OSCE scores and subsequent video analysis showed that standardization for defined performance levels at different OSCE stations is generally possible. Individual deviations from the prescribed examinee responses were observed and occurred primarily with increased complexity of OSCE station content.In the second part of the study, inexperienced examiners assessed a borderline performance significantly lower than their experienced colleagues (13.50 vs. 15.15, p=0.035). No difference was seen in the evaluation of the excellent examinees. Both groups of examiners graded the item “ocial competence” – despite identical standardization – significantly lower for examinees with borderline performances than for excellent examinees (4.13 vs. 4.80, p<0.001).Conclusion: Standardization of examinees for previously defined performance levels is possible, making a new tool available in future not only for OSCE quality assurance, but also for training examiners. Detailed preparation of the OSCE checklists and intensive training of the examinees are essential.This new tool takes on a special importance if standardized OSCEs are integrated into state medical exams and, as such, become high-stakes assessments.

Black-spot syndrome in Caribbean fishes linked to trematode parasite infection (Scaphanocephalus expansus)

Despite the evidence that diseases have increased in marine taxa, parasites remain underrepresented in studies of marine ecology. Recently, observations of black-spot syndrome (BSS) in Caribbean fishes, especially ocean surgeonfishes, Acanthurus tractus (Poey, 1860), have been reported, although its cause(s) has remained conjectural. We investigated the etiology of BSS and whether the pathology was functionally and consistently associated with particular infections. By examining the patterns of BSS among reef fishes in Bonaire, we show that observed dermal spots are the encysted stages (metacercariae) of the heterophyid trematode Scaphanocephalus expansus (Creplin, 1842). Metacercariae were detected within ten species of fishes, with loads ranging from 1–315 per fish. These represent the first published accounts of the genus Scaphanocephalus in the Caribbean and are all new host records. Molecular analysis of sequences identified the infection as a heterophyid, while morphological examinations and comparisons with archival specimens confirmed the species identity as S. expansus. Field-based estimates of BSS by scuba divers and subsequent video analysis correlated positively with parasite counts from necropsy. No such correlation was observed between BSS and metacercariae of a second trematode genus, Bucephalus. The consistent link between host burdens of S. expansus and BSS highlights the potential for low-cost and low-impact assessments in fish populations, including the use of images from citizen scientists and public databases. Taken together, these results help establish the foundation for future investigations into the pathology, geographic distribution, life cycle, and ecological consequences of BSS.

Comparison of Optics and Performance of a Distal Sensor High Definition Cystoscope, a Distal Sensor Standard Definition Cystoscope, and a Fiberoptic Cystoscope

To evaluate performance characteristics and optics of a new generation high-definition distal sensor (HD-DS) flexible cystoscope, a standard-definition distal sensor (SD-DS) cystoscope, and a standard fiberoptic (FO) cystoscope. Three new cystoscopes (HD-DS, SD-DS, and FO) were compared for active deflection, irrigation flow, and optical characteristics. Each cystoscope was evaluated with an empty working channel and with various accessories. Optical characteristics (resolution, grayscale imaging, color representation, depth of field, and image brightness) were measured using United States Air Force (USAF)/Edmund Optics test targets and illumination meter. We digitally recorded a porcine cystoscopy in both clear and blood fields, with subsequent video analysis by 8 surgeons via questionnaire. The HD-DS had a higher resolution than the SD-DS and the FO at both 20 mm (6.35 vs 4.00 vs 2.24 line pairs/mm) and 10 mm (14.3 vs 7.13 vs 4.00 line pairs/mm) evaluations, respectively (P <.001 and P <.001). Color representation and depth of field (P = .001 and P <.001) were better in the HD-DS. When compared to the FO, the HD-DS and SD-DS demonstrated superior deflection up and irrigant flow with and without accessory present in the working channel, whereas image brightness was superior in the FO (P <.001, P = .001, and P <.001, respectively). Observers deemed the HD-DS cystoscope superior in visualization in clear and bloody fields, as well as for illumination. The new HD-DS provided significantly improved visualization in a clear and a bloody field, resolution, color representation, and depth of field compared to SD-DS and FO. Clinical correlation of these findings is pending.

Decreased prolactin levels reduce parental commitment, egg temperatures, and breeding success of incubating male Adélie penguins

Hormones regulate many aspects of an individual's phenotype, including various physiological and behavioral traits. Two hormones have been described as important players in the regulation of parental investment in birds: the glucocorticoid hormone corticosterone and prolactin, a pituitary hormone, widely involved in mediating parental behavior. In comparison with corticosterone, the role of prolactin on parental investment remains poorly documented, and most studies so far have been correlative. In this study, the effects of an experimental decrease of prolactin levels on the incubation behavior of a long-lived seabird species were assessed. Male Adélie penguins were treated with self-degradable bromocriptine pellets, inhibiting prolactin secretion. Filming and subsequent video analysis allowed the determination of a behavioral time budget for birds and their position on the nest, while dummy eggs recorded incubation parameters. Incubation duration and breeding success at hatching were also monitored. As expected, bromocriptine-treatment significantly decreased plasma prolactin levels, but did not affect corticosterone levels. The behavioral time budget of penguins was not affected by the treatment. However, treated birds spent significantly more time in an upright position on the nest. These birds also incubated their eggs at lower temperatures and turned their eggs more frequently than controls, resulting in a lengthened incubation period. Despite this, the treatment was insufficient to trigger nest desertion and eggs of treated birds still hatched, indicating that several endocrine signals are required for the induction of nest abandonment. We suggest that the decreased prolactin levels in treated birds offset their timeline of breeding, so that birds displayed behavior typical of early incubation.

Learning a Contextual Multi-Thread Model for Movie/TV Scene Segmentation

Compared with general videos, movies and TV shows attract a significantly larger portion of people across time and contain very rich and interesting narrative patterns of shots and scenes. In this paper, we aim to recover the inherent structure of scenes and shots in such video narratives. The obtained structure could be useful for subsequent video analysis tasks such as tracking objects across cuts, action retrieval, as well as enriching user browsing and video editing interfaces. Recent research on this problem has mainly focused on combining multiple cues such as scripts, subtitles, sound, or human faces. However, considering that visual information is sufficient for human to identify scene boundaries and some cues are not always available, we are motivated to design a purely visual approach. Observing that dialog patterns occur frequently in a movie/TV show to form a scene, we propose a probabilistic framework to imitate the authoring process. The multi-thread shot model and contextual visual dynamics are embedded into a unified framework to capture the video hierarchy. We devise an efficient algorithm to jointly learn the parameters of the unified model. Experiments on two large datasets containing six movies and 24 episodes of Lost, a popular TV show with complex plot structures, are conducted. Comparative results show that, leveraging only visual cues, our method could successfully recover complicated shot threads and outperform several approaches. Moreover, our method is fast and advantageous for large-scale computation.

February 2013: This Month in JoVE

Here's a look at what's coming up in the February 2013 issue of Journal of Visualized Experiments (JoVE). Since JoVE's first issue, biomedical research has comprised the predominate fraction of our content, and we've got sections for Neuroscience, Clinical and Translational Medicine, Bioengineering, and Immunology. In July 2012, we branched out to the physical sciences with the launch of JoVE Applied Physics. This month, we are pleased to release the first video-articles in JoVE Chemistry, which features subjects ranging from complex biochemistry, to assay development, to chemical engineering, and organic synthesis. In the chemical engineering department, Pandey et al. combine planar lithography with self-folding methods to create 3-dimensional structures inspired by the art of origami. Through exposure to heat or magnetic fields, these microstructures can be induced to fold over objects, and can be used to excise tissue - an application that could translate to taking nanoscale biopsies in vivo. Moving on to biochemistry, Braslavsky and Drori present an experiment designed to measure the effects of ice-binding proteins on ice crystal formation. Through video microscopy and subsequent video analysis, thermal hysteresis-the difference between freezing and melting temperatures-can be determined in the presence of antifreeze proteins, which protect many organisms like bacteria and plants from freezing temperatures. In JoVE Applied Physics, Baranec et al. aim for the stars in our very first astronomy article, which brings the visible universe into focus with the Robo-AO laser adaptive optics system. With the help of a high-power laser beam, this system corrects the incoming light waves that get distorted by atmospheric turbulence so objects in the sky can be seen with high resolution. The authors plan to use this technique to find planets beyond our Solar System, and make precise observations of astronomical phenomena. Looking back at Earth, Qi and Du examine how human movements in spatial and temporal dimensions can be used to study disease transmission. GPS-enabled devices can be used to automatically collect human trajectory data, which the authors process using a novel interactive interface. The trajectories can also be animated in Google Earth. These methods can help detect hot spots for the transmission of infectious diseases, such as influenza. In JoVE Clinical and Translational Medicine, Kim presents a non-invasive method for imaging fetal mouse hearts in utero using high-frequency ultrasonography. This procedure, also called echocardiography, can be used to study normal heart structure and function as well as the mechanisms of cardiovascular disease. It can even be used for the early diagnosis of heart defects, making this a powerful tool with many scientific and clinical applications. From visualizing the far reaches of space, to analyzing human movements in space and time, you've just caught a glimpse of JoVE's new content for February 2013. Like the universe, we continue to expand, and this month marks our arrival at a new frontier with the launch of Chemistry in JoVE: The Journal of Visualized Experiments.

Intraoperative 5-aminolevulinic-acid-induced fluorescence in meningiomas

5-aminolevulinic acid (5-ALA) has gained importance as an intraoperative photodynamic diagnostic agent for the extirpation of malignant gliomas. The application of this technique for resection of meningiomas has barely been explored. The aim of this study was to evaluate the utility of 5-ALA-induced fluorescence as a visual tool in meningioma resection and its correlation with histological findings. A total of 33 consecutive patients undergoing resection of intracranial meningiomas from December 2007 to August 2009 were included in this study. After confirmation of normal liver function, 5-ALA was administered orally (20 mg/kg) within 3-5 h prior to skin incision. All cases were operated on using standard microsurgical and neuronavigation-guided techniques. Intraoperative 440 nm fluorescence was applied periodically during and at the end of resection in order to detect tumor-infiltrated sites. The fluorescence of the tumor was evaluated intraoperatively by the surgeon and confirmed by subsequent video analysis. A total of 32 (97%) patients presented with benign meningiomas (WHO I-II). In 1 (3%) patient, histological anaplastic signs (WHO III) could be demonstrated. 5-ALA-induced fluorescence of the tumor was confirmed in a total of 31 (94%) patients. The fluorescence did not correlate with the histological findings (n = 30 WHO I-II, n = 1 WHO grade III) or with preoperative brain edema and administration of steroids. A total resection could be postoperatively demonstrated in 25 (76%) patients. No adverse effects attributable to 5-ALA occurred. 5-ALA-induced fluorescence is a useful and promising intraoperative tool for the visualization of meningioma tissue. The novel findings demonstrated in this study in terms of high fluorescence and poor correlation with histological findings highlight the usefulness of this technique as a routine visual tool to achieve optimal resection of meningiomas.

Nanorheology of regenerated silk fibroin solution

We have investigated the rheological properties of regenerated silk fibroin (RSF), a viscoelastic material at micro and nano length scales, by video microscopy. We describe here the principles and technique of video microscopy as a tool in such investigations. In this work, polystyrene beads were dispersed in the matrix of RSF polymer and the positions of the embedded beads diffusing were tracked using video microscopy. An optical tweezer was used to transport and locate the bead at any desired site within the micro-volume of the sample, to facilitate the subsequent free-bead video analysis. The position information of the beads was used to obtain the time dependant mean squared displacement (MSD) of the beads in the medium and hence to calculate the dynamic moduli of the medium. We present here the results of rheological measurements of the silk polymer network in solution over a frequency range, whose upper limit is the frame capture rate of our camera at full resolution. The technique is complementary to other microrheological techniques to characterize the material, but additionally enables one to characterize local inhomogeneities in the medium, features that get averaged out in bulk characterization procedures.

Imitative learning by captive western lowland gorillas (Gorilla gorilla gorilla) in a simulated food-processing task.

Although field studies have suggested the existence of cultural transmission of foraging techniques in primates, identification of transmission mechanisms has remained elusive. To test experimentally for evidence of imitation in the current study, we exposed gorillas (Gorilla gorilla gorilla) to an artificial fruit foraging task designed by A. Whiten and D. M. Custance (1996). Gorillas (n=6) watched a human model remove a series of 3 defenses around a fruit. Each of the defenses was removed using 1 of 2 alternative techniques. Subsequent video analysis of gorillas' behavior showed a significant tendency to copy the observed technique on 1 of the individual defenses and the direction of removal on another defense. This is the first statistically reliable evidence of imitation in gorillas. Sequence of defense removal was not replicated. The gorillas' responses were most similar to those of chimpanzees.