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Introduction: Metabolic acidosis is a dangerous and potentially life-threatening condition encountered in the inpatient and emergency department setting. Metabolic acidoses due to renal failure, bicarbonate losses, or lactic acidosis are common conditions, and the appropriate medical management of each is relevant to any inpatient medical provider. Therefore, we created a learning activity that utilizes blackboard-style videos followed by an interactive case-based learning session to help the medical student recognize, diagnose, and manage common causes of metabolic acidosis., Methods: We organized this learning activity by assigning digital videos, followed by application in an interactive team-based format. We created electronic blackboard-style videos and a quiz to assess medical knowledge related to concepts discussed in the videos. Next, we created case resources that facilitate an interactive case-based teaching session so the learners could apply their knowledge and simulate the management of metabolic acidosis., Results: We implemented this activity for 34 medical students. All students viewed the videos prior to the in-class session. In a pre/post assessment of medical knowledge, we observed a significant improvement in quiz scores. Next, we successfully facilitated the case-based active learning session, allowing the assessment of higher-order cognitive skills related to management of patients with metabolic acidosis. Our medical students felt highly satisfied and competent at the completion of our course., Discussion: Our medical students rated this as an excellent learning activity. Others may find this activity useful within the context of any course or rotation related to patients with metabolic acidosis., Competing Interests: None to report., (Copyright © 2019 Berkoben and Roberts.)

The pericarp of monogerm sugar beet seed is rubbed off during processing in order to produce uniformly sized seeds ready for pelleting. This process can lead to mechanical damage, which may cause quality deterioration of the processed seeds. Identification of the mechanical damage and classification of the severity of the injury is important and currently time consuming, as visual inspections by trained analysts are used. This study aimed to find alternative seed quality assessment methods by evaluating a machine vision technique for the classification of five damage types in monogerm sugar beet seeds. Multispectral imaging (MSI) was employed using the VideometerLab3 instrument and instrument software. Statistical analysis of MSI-derived data produced a model, which had an average of 82% accuracy in classification of 200 seeds in the five damage classes. The first class contained seeds with the potential to produce good seedlings and the model was designed to put more limitations on seeds to be classified in this group. The classification accuracy of class one to five was 59, 100, 77, 77 and 89%, respectively. Based on the results we conclude that MSI-based classification of mechanical damage in sugar beet seeds is a potential tool for future seed quality assessment., Competing Interests: The authors declare no conflict of interest.

In this study, a video-based infrared camera (IRC) was investigated as a tool to monitor the body temperature of calves. Body surface temperatures were measured contactless using videos from an IRC fixed at a certain location in the calf feeder. The body surface temperatures were analysed retrospectively at three larger areas: the head area (in front of the forehead), the body area (behind forehead) and the area of the entire animal. The rectal temperature served as a reference temperature and was measured with a digital thermometer at the corresponding time point. A total of nine calves (Holstein-Friesians, 8 to 35 weeks old) were examined. The average maximum temperatures of the area of the entire animal (mean±SD: 37.66±0.90°C) and the head area (37.64±0.86°C) were always higher than that of the body area (36.75±1.06°C). The temperatures of the head area and of the entire animal were very similar. However, the maximum temperatures as measured using IRC increased with an increase in calf rectal temperature. The maximum temperatures of each video picture for the entire visible body area of the calves appeared to be sufficient to measure the superficial body temperature. The advantage of the video-based IRC over conventional IR single-picture cameras is that more than one picture per animal can be analysed in a short period of time. This technique provides more data for analysis. Thus, this system shows potential as an indicator for continuous temperature measurements in calves.

Auditory communication is central to the social interactions of many animals. In fruit flies, males sing to court females. Coen et al. (2016) demonstrate that males can dynamically adjust the loudness of their songs according to the distance to a female., (Copyright © 2016 Elsevier Inc. All rights reserved.)

According to classical sexual selection theory, complex multimodal courtship displays have evolved in males through female choice. While it is well-known that socially monogamous songbird males sing to attract females, we report here the first example of a multimodal dance display that is not a uniquely male trait in these birds. In the blue-capped cordon-bleu (Uraeginthus cyanocephalus), a socially monogamous songbird, both sexes perform courtship displays that are characterised by singing and simultaneous visual displays. By recording these displays with a high-speed video camera, we discovered that in addition to bobbing, their visual courtship display includes quite rapid step-dancing, which is assumed to produce vibrations and/or presumably non-vocal sounds. Dance performances did not differ between sexes but varied among individuals. Both male and female cordon-bleus intensified their dance performances when their mate was on the same perch. The multimodal (acoustic, visual, tactile) and multicomponent (vocal and non-vocal sounds) courtship display observed was a combination of several motor behaviours (singing, bobbing, stepping). The fact that both sexes of this socially monogamous songbird perform such a complex courtship display is a novel finding and suggests that the evolution of multimodal courtship display as an intersexual communication should be considered.

During Arctic summers, sea ice provides resting habitat for Pacific walruses as it drifts over foraging areas in the eastern Chukchi Sea. Climate-driven reductions in sea ice have recently created ice-free conditions in the Chukchi Sea by late summer causing walruses to rest at coastal haulouts along the Chukotka and Alaska coasts, which provides an opportunity to study walruses at relatively accessible locations. Walrus age can be determined from the ratio of tusk length to snout dimensions. We evaluated use of images obtained from a gyro-stabilized video system mounted on a helicopter flying at high altitudes (to avoid disturbance) to classify the sex and age of walruses hauled out on Alaska beaches in 2010-2011. We were able to classify 95% of randomly selected individuals to either an 8- or 3-category age class, and we found measurement-based age classifications were more repeatable than visual classifications when using images presenting the correct head profile. Herd density at coastal haulouts averaged 0.88 walruses/m(2) (std. err. = 0.02), herd size ranged from 8,300 to 19,400 (CV 0.03-0.06) and we documented ∼30,000 animals along ∼1 km of beach in 2011. Within the herds, dependent walruses (0-2 yr-olds) tended to be located closer to water, and this tendency became more pronounced as the herd spent more time on the beach. Therefore, unbiased estimation of herd age-ratios will require a sampling design that allows for spatial and temporal structuring. In addition, randomly sampling walruses available at the edge of the herd for other purposes (e.g., tagging, biopsying) will not sample walruses with an age structure representative of the herd. Sea ice losses are projected to continue, and population age structure data collected with aerial videography at coastal haulouts may provide demographic information vital to ongoing efforts to understand effects of climate change on this species.

Background: Drosophila melanogaster has served as a powerful model system for genetic studies of courtship songs. To accelerate research on the genetic and neural mechanisms underlying courtship song, we have developed a sensitive recording system to simultaneously capture the acoustic signals from 32 separate pairs of courting flies as well as software for automated segmentation of songs., Results: Our novel hardware design enables recording of low amplitude sounds in most laboratory environments. We demonstrate the power of this system by collecting, segmenting and analyzing over 18 hours of courtship song from 75 males from five wild-type strains of Drosophila melanogaster. Our analysis reveals previously undetected modulation of courtship song features and extensive natural genetic variation for most components of courtship song. Despite having a large dataset with sufficient power to detect subtle modulations of song, we were unable to identify previously reported periodic rhythms in the inter-pulse interval of song. We provide detailed instructions for assembling the hardware and for using our open-source segmentation software., Conclusions: Analysis of a large dataset of acoustic signals from Drosophila melanogaster provides novel insight into the structure and dynamics of species-specific courtship songs. Our new system for recording and analyzing fly acoustic signals should therefore greatly accelerate future studies of the genetics, neurobiology and evolution of courtship song.

Endurance running may have a long evolutionary history in the hominin clade but it was not until very recently that humans ran wearing shoes. Research on modern habitually unshod runners has suggested that they utilize a different biomechanical strategy than runners who wear shoes, namely that barefoot runners typically use a forefoot strike in order to avoid generating the high impact forces that would be experienced if they were to strike the ground with their heels first. This finding suggests that our habitually unshod ancestors may have run in a similar way. However, this research was conducted on a single population and we know little about variation in running form among habitually barefoot people, including the effects of running speed, which has been shown to affect strike patterns in shod runners. Here, we present the results of our investigation into the selection of running foot strike patterns among another modern habitually unshod group, the Daasanach of northern Kenya. Data were collected from 38 consenting adults as they ran along a trackway with a plantar pressure pad placed midway along its length. Subjects ran at self-selected endurance running and sprinting speeds. Our data support the hypothesis that a forefoot strike reduces the magnitude of impact loading, but the majority of subjects instead used a rearfoot strike at endurance running speeds. Their percentages of midfoot and forefoot strikes increased significantly with speed. These results indicate that not all habitually barefoot people prefer running with a forefoot strike, and suggest that other factors such as running speed, training level, substrate mechanical properties, running distance, and running frequency, influence the selection of foot strike patterns.

Two endotracheal tubes (ETTs) are available for use in operative suites for intubation: the Parker Flex-Tip (PFT, Parker Medical) and the standard Mallinckrodt (Covidien). To the authors' knowledge, no study has compared these 2 ETTs with each other when the anesthesia provider uses the GlideScope video laryngoscope (Verathon) for intubation. The purpose of the study was to determine if there are differences related to ease of intubation reported by anesthesia providers who use the PFT tube compared with the standard tube while using the GlideScope. The study was a randomized block intervention design. The sample consisted of 58 observed intubations in an operating room setting. Data analysis was completed with a 2-factor analysis of covariance using 2 covariates. The PFT tube in suboptimal conditions demonstrated a significantly greater ease of intubation, as measured by decreased time for ETT insertion and greater ease of ETT insertion score. The number of redirections at the glottis to intubate the trachea once the glottis was visualized was not statistically different. Based on the findings from this study, anesthesia providers may want to consider the use of the PFT tube when using the GlideScope to promote ease of intubation.

In this paper, we present a large database of over 50,000 user-labeled videos collected from YouTube. We develop a compact representation called "tiny videos" that achieves high video compression rates while retaining the overall visual appearance of the video as it varies over time. We show that frame sampling using affinity propagation-an exemplar-based clustering algorithm-achieves the best trade-off between compression and video recall. We use this large collection of user-labeled videos in conjunction with simple data mining techniques to perform related video retrieval, as well as classification of images and video frames. The classification results achieved by tiny videos are compared with the tiny images framework [24] for a variety of recognition tasks. The tiny images data set consists of 80 million images collected from the Internet. These are the largest labeled research data sets of videos and images available to date. We show that tiny videos are better suited for classifying scenery and sports activities, while tiny images perform better at recognizing objects. Furthermore, we demonstrate that combining the tiny images and tiny videos data sets improves classification precision in a wider range of categories.

Fundus photography in adults and cooperative children is possible with a fundus camera or by using a slit lamp-mounted digital camera. Retcam TM or a video indirect ophthalmoscope is necessary for fundus imaging in infants and young children under anesthesia. Herein, a technique of converting and using a digital video camera into a video indirect ophthalmoscope for fundus imaging is described. This device will allow anyone with a hand-held video camera to obtain fundus images. Limitations of this technique involve a learning curve and inability to perform scleral depression.

With a micro-electro-mechanical system (MEMS) mirror, we successfully developed a miniaturized epi-third-harmonic-generation (epi-THG) fiber-microscope with a video frame rate (31 Hz), which was designed for in vivo optical biopsy of human skin. With a large-mode-area (LMA) photonic crystal fiber (PCF) and a regular microscopic objective, the nonlinear distortion of the ultrafast pulses delivery could be much reduced while still achieving a 0.4 microm lateral resolution for epi-THG signals. In vivo real time virtual biopsy of the Asian skin with a video rate (31 Hz) and a sub-micron resolution was obtained. The result indicates that this miniaturized system was compact enough for the least invasive hand-held clinical use.

Although applied behavior analysis has generated many highly effective behavior-change procedures, the procedures have not always been effectively disseminated. One solution to this problem is the use of video technology, which has been facilitated by the ready availability of video production equipment and software and multiple distribution methods (e.g., DVD, online streaming). We review a recent DVD that was produced to disseminate the successful experimental functional analysis procedure. The review is followed by general recommendations for disseminating behavior-analytic procedures via video technology.

Urethral catheterization of the female dog is known to be a challenging procedure. The authors describe a catheterization technique in which they use a rigid endoscope to visualize the canine urogenital vestibule during the procedure. The technique is particularly helpful as a training tool for students who are not yet experienced with the canine anatomy. The endoscope is attached to a video camera and monitor, allowing others to observe and learn the procedure.

Some psychological experiments require placement of visual and auditory stimuli on predefined frames in a videotape. We introduce STIVID (STImuli on VIDeo) as a method of performing this task STIVID can add images, words, simple shapes, and audio tones to specific frames of existing video files created in AVI format. STIVID is written in Visual Basic and uses VBScripts to modify the AVI files. Three applications of this program are discussed: adding stimuli for reaction time experiments with couples watching a relational conflict, use of distractors in ADHD experiments, and placing eye masks on actors in existing videotapes to manipulate perceptibility of the target's facial expression during the mind-reading process.

Aims: To investigate the use of intra-oral video cameras (IOVCs) for occlusal caries detection., Design: Eighty premolars and molars set-up to simulate clinical conditions were examined by six examiners using three techniques: visual examination (EX), an IOVC (CAM) and by watching a video that was recorded using an intra-oral video camera (VID). The teeth were then sectioned for histological validation., Results: 30 surfaces had lesions limited to enamel and 39 had lesions extending into dentine. Sensitivity scores at the D1 threshold (enamel and dentine lesions) were 43% (EX), 68% (CAM) and 77% (VID) whilst the specificity scores were 92% (EX), 64% (CAM) and 60% (VID). Corresponding results at the D3 threshold (caries extending into dentine) were 27%, 42%, 60%, 97%, 99% and 77%., Conclusions: Compared to unaided vision, the use of an IOVC significantly increases the number of occlusal lesions detected, however, there is a rise in false positive scores at the D1 threshold. The use of the video technique also significantly increases the number of occlusal lesions detected but with a concurrent rise in false positive scores at both thresholds.

Background: There is increasing emphasis on performance-based assessment of clinical competence. The High Fidelity Patient Simulator (HPS) may be useful for assessment of clinical practice in anaesthesia, but needs formal evaluation of validity, reliability, feasibility and effect on learning. We set out to assess the reliability of a global rating scale for scoring simulator performance in crisis management., Methods: Using a global rating scale, three judges independently rated videotapes of anaesthetists in simulated crises in the operating theatre. Five anaesthetists then independently rated subsets of these videotapes., Results: There was good agreement between raters for medical management, behavioural attributes and overall performance. Agreement was high for both the initial judges and the five additional raters., Conclusions: Using a global scale to assess simulator performance, we found good inter-rater reliability for scoring performance in a crisis. We estimate that two judges should provide a reliable assessment. High fidelity simulation should be studied further for assessing clinical performance.

We describe imaging the luminance of green fluorescent protein (GFP)-expressing bacteria from outside intact infected animals. This simple, nonintrusive technique can show in great detail the spatial-temporal behavior of the infectious process. The bacteria, expressing the GFP, are sufficiently bright as to be clearly visible from outside the infected animal and recorded with simple equipment. Introduced bacteria were observed in several mouse organs including the peritoneal cavity, stomach, small intestine, and colon. Instantaneous real-time images of the infectious process were acquired by using a color charge-coupled device video camera by simply illuminating mice at 490 nm. Most techniques for imaging the interior of intact animals may require the administration of exogenous substrates, anesthesia, or contrasting substances and require very long data collection times. In contrast, the whole-body fluorescence imaging described here is fast and requires no extraneous agents. The progress of Escherichia coli-GFP through the mouse gastrointestinal tract after gavage was followed in real-time by whole-body imaging. Bacteria, seen first in the stomach, migrated into the small intestine and subsequently into the colon, an observation confirmed by intravital direct imaging. An i.p. infection was established by i.p. injection of E. coli-GFP. The development of infection over 6 h and its regression after kanamycin treatment were visualized by whole-body imaging. This imaging technology affords a powerful approach to visualizing the infection process, determining the tissue specificity of infection, and the spatial migration of the infectious agents.

Purpose: Few data describe the sensitivity of a "Seizure Activity Detection Computer" (SzAC) in childhood video/EEG (VEEG) monitoring, especially for very young children. We examined the accuracy of SzAC in childhood VEEG monitoring in different pediatric age groups., Methods: We visually analyzed VEEG monitoring samples for randomly designated subsets of 56 patients with childhood epilepsy, reviewing 335 visually detected electrographic seizures to analyze the sensitivity of SzAC for each age group as well as the electrographic characteristics affecting the sensitivity of automated computer-based seizure detection., Results: SzAC was positive in 227 of 335 (67.8%) visually identified electrographic seizures in the entire study group. The SzAC sensitivity for infants (age 2 months to 2 years) was 59.7% (43 of 72 seizures); for young children (age 3-10 years), sensitivity 56.5% (91 of 161 seizures). In adolescents (age 11-18 years), SzAC was positive in 93 of 102 (91.2%) seizures--i.e., in a significantly greater number of seizures than in younger age groups. SzAC was significantly less sensitive in detecting electrographic seizures characterized as being of short duration or of low voltage., Conclusions: The overall sensitivity of SzAC in detecting childhood electrographic seizures was 67.8%. The sensitivity was significantly less in younger age groups as compared with that in children aged >11 years. Electrographic seizures of relatively short duration or low voltage were often missed by SzAC.

A new seizure-monitoring apparatus containing a piezoceramic vibration sensor combined with videotape recording was developed. Behavioral analysis of Ihara's genetically epileptic rat (IGER), which is a recently developed novel mutant with spontaneously limbic-like seizures, was performed using this new device. Twenty 8-month-old male IGERs were monitored continuously for 72 h. Abnormal behaviors were detected by use of a vibration recorder, and epileptic seizures were confirmed by videotape recordings taken synchronously with vibration recording. Representative forms of seizures were generalized convulsions and circling seizures. Generalized convulsions were found in 13 rats, and circling seizures in 7 of 20 animals. Two rats had generalized and circling seizures, and two rats did not have seizures. Although there was no apparent circadian rhythm to the generalized seizures, circling seizures occurred mostly between 1800 and 0800 h. A correlation between the sleep-wake cycle and the occurrence of circling seizures seems likely. Without exception, all the seizure actions were recorded by the vibration recorder and the videotape recorder. To eliminate the risk of a false-negative result, investigators scrutinized the information obtained from the vibration sensor and the videotape recorder. The newly developed seizure-monitoring system was found to facilitate detailed analysis of epileptic seizures in rats.

A new, automatic method for determination of human ocular torsion (OT) was developed based on the tracking of iris patterns in digitized video images. Instead of quantifying OT by means of cross-correlation of circular iris samples, a procedure commonly applied, this new method automatically selects and recovers a set of 36 significant patterns in the iris by the technique of template matching as described by In den Haak et al. Each relocated landmark results in a single estimate of the torsion angle. A robust algorithm estimates OT from this total set of individually determined torsion angles, thereby largely correcting for errors which may arise due to misjudgement of the rotation center. The new method reproduced OT in a prepared set of images of an artificial eye with an accuracy of 0.1 degree. In a sample of 256 images of human eyes, a practical reliability of 0.25 degrees was achieved. To illustrate the method's usefulness, an experiment is described in which ocular torsion was measured during two dynamic conditions of whole-body roll, namely during sinusoidally pendular motion about either an earth horizontal or earth vertical axis (that is "with" and "without" otolith stimulation, respectively).

A video-based data acquisition and interactive multimedia data extraction system are described for measuring and synchronizing large quantities of biomechanical analog data with arbitrary events and activities. Analog signals from up to 32 channels are digitized, frequency-shift key (FSK) coded, and recorded directly onto the audio tracks of a video tape in synchronization with the video information. The data acquisition system includes an A/D converter that digitizes up to 16 multiplexed channels of 8-b data at a fixed sample rate between 60 and 960 Hz, and an FSK modem that transfers the data onto one of two VHS high fidelity (20 Hz-20 kHz bandwidth) audio tracks. Twenty megabytes of digitized data and time codes, along with associated video and normal audio are contained on a conventional 120-min video tape. An analyst interactively reviews the video tape off-line using a computer-controlled VCR and identifies specific events that divide arbitrary activities into time segments. The computer automatically extracts the biomechanical data corresponding to each time segment for further processing or analysis. This system is useful for ergonomics, gait analysis, sports medicine, sleep laboratory, biomechanics, or any application where complex visual events are synchronized with low-frequency analog data.

We developed an easy to use and non-invasive method to study sarcomere motion of enzymatically isolated myocytes which can be simultaneously combined with auxotonic force detection, thus being very useful when studying the contractile performance of cardiac cells. This method basically consists in analyzing the periodicity of the cell striation pattern using the Cooley-Tukey fast Fourier transform (FFT) algorithm on a video image of the cell during the course of the experiment. A longitudinal fraction of the cell image is recorded with a CCD TV camera, digitized, then transiently stored on a computer and used to calculate the spectrum corresponding to the distribution of the sarcomere lengths (SL). The method gives a real-time measurement of the most probable value of sarcomere length in one isolated cell with a temporal resolution of 20 ms. When used on a cell attached between two carbon fibers, the auxotonic force developed by the cell upon electrical stimulation can be simultaneously measured together with the SL in various conditions of stretch. Preliminary results have been presented in abstract form (Gannier et al., vol 24, pp. S47, 1992).

An image processing technique with associated hardware was developed to quantitatively extract hyoid bone motion from realtime submandibular ultrasound images recorded during the swallowing act. Videofluorographic imaging, the "gold standard" of swallowing studies, was recorded simultaneously and synchronized to the ultrasound. Hyoid position obtained from the ultrasound was validated based on the videofluorography using personal computer-based image processing methods.

Tumor necrosis factor-alpha (TNF-alpha), a cytokine produced by mononuclear cells in response to endotoxin, inhibits neutrophil chemotaxis. We analyzed the effects of TNF-alpha on the orientation and movement of individual neutrophils in a chemoattractant gradient. Neutrophils, treated or untreated with TNF-alpha, were observed migrating in a gradient of the chemotactic peptide N-formyl-1-methionyl-1-leucyl-1-phenylalanine (fMLP) on a specially constructed chamber (Zigmond bridge). The movement of these cells was videotaped, digitized, and then tracked using a newly designed computer algorithm. The data obtained from this algorithm were then utilized to calculate distance traveled, speed and ability to polarize and migrate in a directed manner for each individual cell. TNF-alpha-treated cells behaved like cells not exposed to fMLP in that they failed to orient in a chemotactic gradient and moved in a manner similar to randomly migrating cells. This study provides unique observations of the effect of TNF-alpha on multiple parameters of PMN migration.

The development of computerized and semi-automated motion analysis systems has made the study of human motion more widely available in research and clinical settings. Although many of these systems are currently used by physical therapists, the accuracy and reproducibility of some of these systems in estimating joint angles have not been reported. In this study, the accuracy and reproducibility of angle measurements obtained by use of the Motion Analysis video system were evaluated under static conditions using a standard goniometer. Reflective markers placed on a goniometer were recorded by two video cameras at 17 angles, from 20 to 180 degrees, in 10-degree increments. Recordings of the goniometer were made at three locations within the field of view of the cameras. The intraclass correlation coefficient for each location tested was .99. Average within-trial variability was less than 0.4 degree at all locations. A linear regression of the system-calculated angles and reference angles for all locations had slopes near unity (ie, 1) and intercepts that were not statistically different from zero. A preliminary evaluation of the system under dynamic conditions revealed that distances were slightly underestimated, regardless of where the movement occurred within the calibration cube.

Accurate measurement of the biomass and size distribution of picoplankton cells (0.2 to 2.0 microns) is paramount in characterizing their contribution to the oceanic food web and global biogeochemical cycling. Image-analyzed fluorescence microscopy, usually based on video camera technology, allows detailed measurements of individual cells to be taken. The application of an imaging system employing a cooled, slow-scan charge-coupled device (CCD) camera to automated counting and sizing of individual picoplankton cells from natural marine samples is described. A slow-scan CCD-based camera was compared to a video camera and was superior for detecting and sizing very small, dim particles such as fluorochrome-stained bacteria. Several edge detection methods for accurately measuring picoplankton cells were evaluated. Standard fluorescent microspheres and a Sargasso Sea surface water picoplankton population were used in the evaluation. Global thresholding was inappropriate for these samples. Methods used previously in image analysis of nanoplankton cells (2 to 20 microns) also did not work well with the smaller picoplankton cells. A method combining an edge detector and an adaptive edge strength operator worked best for rapidly generating accurate cell sizes. A complete sample analysis of more than 1,000 cells averages about 50 min and yields size, shape, and fluorescence data for each cell. With this system, the entire size range of picoplankton can be counted and measured.

A system for monitoring blood flow in femorodistal vein grafts with Doppler ultrasonography in the immediate postoperative period has been developed. Twenty-three grafts have been monitored for periods of up to 72 hours. Seventeen grafts have remained patent at minimum follow-up of 6 months, and six grafts occluded in the immediate postoperative period. Successful Doppler recordings were obtained in 16 successful and all failed grafts. Fast Fourier transform analysis of the Doppler signals was performed, and pulsatility index and time-averaged mean velocity were derived from the spectral information. Successful grafts displayed hyperemic flow with pulsatility index less than 2 and time-averaged mean velocity greater than 10 cm/sec. Failed grafts could be classified in two groups: those that occluded less than 24 hours after operation and those that occluded after 24 hours after operation. Short-term failure was categorized by highly pulsatile flow, with pulsatility index rising rapidly and time-averaged mean velocity falling correspondingly before actual cessation of flow. Delayed failure was less well defined but was suggested by failure to develop, or early deviation from, the hyperemic flow seen in successful grafts. Occlusion was heralded by development of the pulsatile pattern seen in the short-term failure group.

A rapid technique for counting and classifying large ovarian follicles of domestic animals is described. Using a cryostat, 250-micrograms thick sections were cut from the frozen ovary; an image of the surface of each ovarian section was recorded on videotape. By replaying the videotape, the largest profile of each follicle larger than 1 mm in diameter was readily identified and measured. The presence or absence of atresia was determined by applying standard histological methods to fragments of individual follicles taken from the frozen sections. The results obtained are similar to those found using previous methods and demand only one-quarter of the time.

Videotape offers an inexpensive method for off-line viewing of dynamic radionuclide cardiac studies. Two approaches to videotaping have been explored and demonstrated to be feasible. In the first, a video camera in conjunction with a cassette-type recorder is used to record from the computer display scope. Alternatively, for computer systems already linked to video display units, the video signal can be routed directly to the recorder. Acceptance and use of tracer cardiology studies will be enhanced by increased availability of the studies for clinical review. Videotape offers an inexpensive flexible means of achieving this.

Direct videotape recording of images from computer display terminals is often not possible because of the nonstandard outputs of these systems. A video-sync mixer is described that permits black-and-white recording on standard 3/4-in. videotape cassettes.

To elucidate the molecular mechanism of muscle contraction resulting from the ATP-dependent actin-myosin interaction, we constructed an assay system with which both the force and the movement produced by the actin-myosin interaction in vitro can be simultaneously recorded and analyzed. The assay system consisted of the giant internodal cells of an alga, Nitellopsis obtusa, which contain well-organized arrays of actin filaments (actin cables) running along the cell long axis, and a glass microneedle (tip diameter, approximately 7 microns; elastic coefficient, approximately 40 pN/microns), which was coated with skeletal muscle myosin at the tip and extended from a micromanipulator at right angles with the actin cables. When the myosin-coated tip of the microneedle was brought into contact with the exposed surface of the actin cables, it exhibited ATP-dependent movement along the actin cables over a distance of 20-150 microns in 20-200 s (20-23 degrees C) and eventually stopped due to a balance between forces generated by the actin-myosin interaction (800-6000 pN) and by the bent microneedle. Since the load on the force-generating myosin molecules increased with the bending displacement of the microneedle (auxotonic condition), the relation between the load and the sliding velocity of the myosin heads past the actin cables was determined from the time course of the microneedle movement recorded with a video system. The shape of the force-velocity curve thus obtained was convex upwards, similar to that of the force-velocity curve of intact frog muscle fibers obtained under the auxotonic condition.

An inexpensive interface is described that performs direct transfer of digitized data from the digital audio processor and video cassette recorder based data acquisition system designed by Bezanilla (1985, Biophys. J., 47:437-441) to an IBM PC/XT microcomputer. The FORTRAN callable software that drives this interface is capable of controlling the video cassette recorder and starting data collection immediately after recognition of a segment of previously collected data. This permits piecewise analysis of long intervals of data that would otherwise exceed the memory capability of the microcomputer.

A modified digital audio processor, a video cassette recorder, and some simple added circuitry are assembled into a recording device of high capacity. The unit converts two analog channels into digital form at 44-kHz sampling rate and stores the information in digital form in a common video cassette. Bandwidth of each channel is from direct current to approximately 20 kHz and the dynamic range is close to 90 dB. The total storage capacity in a 3-h video cassette is 2 Gbytes. The information can be retrieved in analog or digital form.