Movie Frames Research Articles

The pressure field of imploding lightbulbs

The implosion of A19 incandescent lightbulbs in a high-pressure water environment is studied in a 1.77-m-diameter steel tank. Underwater blast sensors are used to measure the dynamic pressure field near the lightbulbs and the implosions are photographed with a high-speed movie camera at a frame rate of 24,000 pps. The movie camera and the pressure signal recording system are synchronized to enable correlation of features in the movie frames with those in the pressure records. It is found that the gross dimensions and weight of the bulbs are very similar from one bulb to another, but the ambient water pressure at which a given bulb implodes (\(P_a\), called the implosion pressure) varies from 6.29 to 11.98 atmospheres, probably due to inconsistencies in the glass wall thickness and perhaps other detailed characteristics of the bulbs. The dynamic pressures (the local pressure minus \(P_a\), as measured by the sensors) first drop during the implosion and then reach a strong positive peak at about the time that the bulb reaches minimum volume. The peak dynamic pressure varies from 3.61 to 28.66 atmospheres. In order to explore the physics of the implosion process, the dynamic pressure signals are compared to calculations of the pressure field generated by the collapse of a spherical bubble in a weakly compressible liquid. The wide range of implosion pressures is used in combination with the calculations to explore the effect of the relative liquid compressibility and the bulb itself on the dynamic pressure field.

A Psychophysical Study Exploring Judder Using Fundamental Signals and Complex Imagery

There are well-known observations of movie content being displayed at different frame rates. Although the terms are not consistent across the industry, four main degradations are observed of the signal as compared to nonsampled motion (i.e., real-world motion): (1) nonsmooth motion, (2) false multiple edges, (3) flickering, and (4) motion blur. In natural imagery, all four of these effects are generally visible at typical movie frame rates. The spatiotemporal window of visibility has proved successful in describing when motion looks distorted from the real-world smooth motion. However, that model predicts only detection performance and does not address the appearance or magnitude of motion distortions. In addition, well-known image capture and display parameters are also involved with frame rate questions, such as exposure duty cycle (angle), object speed, and object contrast. There are also known interactions with brightness and contrast, which are also generally linked in the end-to-end system. For example, the Ferry-Porter law1 of psychophysics indicates the temporal frequency bandwidth of vision increases with increasing adapting luminance. We aimed to isolate the nonsmooth motion component of judder in a psychophysical study by using fundamental test signals, such as the Gabor signal. Two-interval forced choice methodology was used to generate interval scales of the magnitude of judder, or judderness. Results are presented for the viewer assessment of the magnitude of judder/judderness as a function of these key parameters tested in isolation.

Seeing tobacco mosaic virus through direct electron detectors.

With the introduction of direct electron detectors (DED) to the field of electron cryo-microscopy, a wave of atomic-resolution structures has become available. As the new detectors still require comparative characterization, we have used tobacco mosaic virus (TMV) as a test specimen to study the quality of 3D image reconstructions from data recorded on the two direct electron detector cameras, K2 Summit and Falcon II. Using DED movie frames, we explored related image-processing aspects and compared the performance of micrograph-based and segment-based motion correction approaches. In addition, we investigated the effect of dose deposition on the atomic-resolution structure of TMV and show that radiation damage affects negative carboxyl chains first in a side-chain specific manner. Finally, using 450,000 asymmetric units and limiting the effects of radiation damage, we determined a high-resolution cryo-EM map at 3.35 Å resolution. Here, we provide a comparative case study of highly ordered TMV recorded on different direct electron detectors to establish recording and processing conditions that enable structure determination up to 3.2 Å in resolution using cryo-EM.

Defeating Camcorder Piracy by Temporal Psychovisual Modulation

We present a new video projection technique to defeat camcorder piracy in movie theaters using the newly emerged display paradigm of temporal psychovisual modulation. The technique exploits the difference in image formation mechanisms between human eyes and digital cameras: in the human visual system, images are formed via continuous integration of the light field, whereas digital video acquisition is based on discrete sampling of light sensors. A movie frame is decomposed into multiple so-called shale frames such that, when these shale frames are displayed at a frame rate higher than 60 Hz, the human viewers will experience normal movie presentation without any noticeable artifacts, but the video frames captured by camcorders will contain severe, highly objectionable artifacts, depriving the pirated video contents of any commercial values.

Development of a New Method to Track Multiple Honey Bees with Complex Behaviors on a Flat Laboratory Arena

A computer program that tracks animal behavior, thereby revealing various features and mechanisms of social animals, is a powerful tool in ethological research. Because honeybee colonies are populated by thousands of bees, individuals co-exist in high physical densities and are difficult to track unless specifically tagged, which can affect behavior. In addition, honeybees react to light and recordings must be made under special red-light conditions, which the eyes of bees perceive as darkness. The resulting video images are scarcely distinguishable. We have developed a new algorithm, K-Track, for tracking numerous bees in a flat laboratory arena. Our program implements three main processes: (A) The object (bee's) region is detected by simple threshold processing on gray scale images, (B) Individuals are identified by size, shape and spatiotemporal positional changes, and (C) Centers of mass of identified individuals are connected through all movie frames to yield individual behavioral trajectories. The tracking performance of our software was evaluated on movies of mobile multi-artificial agents and of 16 bees walking around a circular arena. K-Track accurately traced the trajectories of both artificial agents and bees. In the latter case, K-track outperformed Ctrax, well-known software for tracking multiple animals. To investigate interaction events in detail, we manually identified five interaction categories; ‘crossing’, ‘touching’, ‘passing’, ‘overlapping’ and ‘waiting’, and examined the extent to which the models accurately identified these categories from bee's interactions. All 7 identified failures occurred near a wall at the outer edge of the arena. Finally, K-Track and Ctrax successfully tracked 77 and 60 of 84 recorded interactive events, respectively. K-Track identified multiple bees on a flat surface and tracked their speed changes and encounters with other bees, with good performance.

Pedestrian detection and tracking using temporal differencing and HOG features

This article proposes a multiple human detection and tracking approach. A moving person identification technique is provided first. The video objects are detected using a novel temporal differencing based procedure and several mathematical morphology-based operations. Then, our technique determines what moving image objects represent pedestrian people, by testing several conditions related to human bodies and detecting the skin regions from the movie frames. A robust human tracking method using a Histogram of Oriented Gradient (HOG) based template matching process is then introduced in our paper. Some person detection and tracking experiments and method comparisons are also described.

When standard RANSAC is not enough: cross-media visual matching with hypothesis relevancy

The same scene can be depicted by multiple visual media. For example, the same event can be captured by a comic image or a movie frame; the same object can be represented by a photograph or by a 3D computer graphics model. In order to extract the visual analogies that are at the heart of cross-media analysis, spatial matching is required. This matching is commonly achieved by extracting key points and scoring multiple, randomly generated mapping hypotheses. The more consensus a hypothesis can draw, the higher its score. In this paper, we go beyond the conventional set-size measure for the quality of a match and present a more general hypothesis score that attempts to reflect how likely is each hypothesized transformation to be the correct one for the matching task at hand. This is achieved by considering additional, contextual cues for the relevance of a hypothesized transformation. This context changes from one matching task to another and reflects different properties of the match, beyond the size of a consensus set. We demonstrate that by learning how to correctly score each hypothesis based on these features we are able to deal much more robustly with the challenges required to allow cross-media analysis, leading to correct matches where conventional methods fail.

Sparse coding model captures V1 population response statistics to natural movies

Local populations of sensory cortical cells exhibit a diverse range of activity patterns. However, classical approaches have neither fully accounted for nor characterized this heterogeneity, especially in response to natural stimuli. First, classical single cell recordings suffered from sampling bias and favored highly responsive cells [1]. Second, common approaches considered mostly the average activity over different cell classes, without a full description of the statistical distribution over the entire population [2]. Recent studies started to address these issues [3,4]. In this study, we make further inroads by recording simultaneous single unit activities across cortical layers in cat V1 in response to natural movies using a silicon polytrode, and comparing the population statistics to the predictions from a dynamical system implementation of the sparse coding model [5,6], with a linear-nonlinear model as control. We analyzed data sets from two recording sessions in anaesthetized cats viewing natural movies. To quantitatively measure the difference between model predictions and the recording, we used the earth mover's distance [7] to quantify the dissimilarities between the distributions of the recorded response and those predicted by sparse coding and linear-nonlinear model. We show that: (1) The population firing rate distribution is close to exponential in both the recorded data and the sparse coding model in response to natural movies; (2) The response correlation between unit activities is small regardless of the size of receptive field overlap, when using a binning window synced to the movie frame. A similar relationship between the response correlation and receptive field overlap is observed in the sparse coding model; (3) A linear-nonlinear model could predict the exponential firing rate distribution, but not the correlation structure.

SU‐C‐141‐03: Assessing ITV and PTV Coverage for Mobile Tumors with Real‐Time Fluoroscopy Imaging

Purpose: To evaluate the appropriateness of the internal target volume (ITV) and planning target volume (PTV) generated based on 4DCT simulation using real‐time kV fluoroscopic imaging. Methods: 4DCT scans of a moving (3D) phantom with implanted fiducials were acquired using three‐dimensional lung tumor locations derived from Cyberknife Synchrony system log files. Data from 5 patients consisting of tumor trajectories derived from the Synchrony model and from three different treatment fractions were used in this analysis. All patients in this study had a peak‐to‐peak respiratory amplitude between 7–15mm. The fiducials were contoured on ten phases of the 4DCT scans, and ITVs and PTVs (ITV+5mm) were created for each marker. Fluoroscopic images were acquired for all trajectories at a rate of 15Hz for 20–30 seconds in two imaging planes: anterior‐posterior and lateral. The markers were tracked using the Varian Intra‐fraction Motion Review (IMR) software, using a reference movie frame in which marker locations were matched against their corresponding positions on the DRR. The tracked marker positions were classified as within the ITV, between the ITV and the PTV, and outside the PTV in each frame. Results: The fiducial was detected inside of the ITV in 82.4% (71.7%) of frames in the lateral plane (AP plane), between the ITV and PTV in 17.4% (28.0%) of lateral (AP) frames, and detected outside the PTV in 0.2% (0.3%) of lateral (AP) frames. When the marker was between the ITV and the PTV, the distance from marker to ITV was >3mm in 21% (27%) in lateral (AP) plane images. Conclusion: We have developed a method to quantify the degree to which the planned ITV and PTV encompass the extent of tumor motion. The tumor was detected outside of the ITV more often in the AP‐plane of imaging, and detected within the PTV in nearly all cases. Varian Medical Systems

Localizing non-retinotopically moving objects.

How does the brain determine the position of moving objects? It turns out to be rather complex to answer this question when we realize that the brain has to solve the motion correspondence problem in two kinds of reference frames: Retinotopic and non-retinotopic ones. We show that visual objects are mislocalized along a non-retinotopic motion direction. Observers viewed two successive movie frames each consisting of an outlined square and two target elements inside the square. In the non-retinotopic condition the elements as well as the square moved vertically while two bars also centripetally or centrifugally moved. In the retinotopic condition the vertical movement of them was removed from the stimuli. The task of the observers was to judge a relative position of the elements. Consequently, the elements were mislocalized in the direction of both retinotopic and non-retinotopic motion, although the mislocalization was significantly larger in the retinotopic than in the non-retinotopic conditions. The results suggest that non-retinotopic as well as retinotopic motion processing contributes to the determination of perceived positions of moving objects.

Individual-level space-time analyses of emergency department data using generalized additive modeling.

BackgroundAlthough daily emergency department (ED) data is a source of information that often includes residence, its potential for space-time analyses at the individual level has not been fully explored. We propose that ED data collected for surveillance purposes can also be used to inform spatial and temporal patterns of disease using generalized additive models (GAMs). This paper describes the methods for adapting GAMs so they can be applied to ED data.MethodsGAMs are an effective approach for modeling spatial and temporal distributions of point-wise data, producing smoothed surfaces of continuous risk while adjusting for confounders. In addition to disease mapping, the method allows for global and pointwise hypothesis testing and selection of statistically optimum degree of smoothing using standard statistical software. We applied a two-dimensional GAM for location to ED data of overlapping calendar time using a locally-weighted regression smoother. To illustrate our methods, we investigated the association between participants’ address and the risk of gastrointestinal illness in Cape Cod, Massachusetts over time.ResultsThe GAM space-time analyses simultaneously smooth in units of distance and time by using the optimum degree of smoothing to create data frames of overlapping time periods and then spatially analyzing each data frame. When resulting maps are viewed in series, each data frame contributes a movie frame, allowing us to visualize changes in magnitude, geographic size, and location of elevated risk smoothed over space and time. In our example data, we observed an underlying geographic pattern of gastrointestinal illness with risks consistently higher in the eastern part of our study area over time and intermittent variations of increased risk during brief periods.ConclusionsSpatial-temporal analysis of emergency department data with GAMs can be used to map underlying disease risk at the individual-level and view changes in geographic patterns of disease over time while accounting for multiple confounders. Despite the advantages of GAMs, analyses should be considered exploratory in nature. It is possible that even with a conservative cutoff for statistical significance, results of hypothesis testing may be due to chance. This paper illustrates that GAMs can be adapted to measure geographic trends in public health over time using ED data.

Rapid dopaminergic and GABAergic modulation of calcium and voltage transients in dendrites of prefrontal cortex pyramidal neurons

The physiological responses of dendrites to dopaminergic inputs are poorly understood and controversial. We applied dopamine on one dendritic branch while simultaneously monitoring action potentials (APs) from multiple dendrites using either calcium-sensitive dye, voltage-sensitive dye or both. Dopaminergic suppression of dendritic calcium transients was rapid (<0.5 s) and restricted to the site of dopamine application. Voltage waveforms of backpropagating APs were minimally altered in the same dendrites where dopamine was confirmed to cause large suppression of calcium signals, as determined by dual voltage and calcium imaging. The dopamine effects on dendritic calcium transients were fully mimicked by D1 agonists, partially reduced by D1 antagonist and completely insensitive to protein kinase blockade; consistent with a membrane delimited mechanism. This dopamine effect was unaltered in the presence of L-, R- and T-type calcium channel blockers. The somatic excitability (i.e. AP firing) was not affected by strong dopaminergic stimulation of dendrites. Dopamine and GABA were then sequentially applied on the same dendrite. In contrast to dopamine, the pulses of GABA prohibited AP backpropagation distally from the application site, even in neurons with natural Cl− concentration (patch pipette removed). Thus, the neocortex employs at least two distinct mechanisms (dopamine and GABA) for rapid modulation of dendritic calcium influx. The spatio-temporal pattern of dendritic calcium suppression described in this paper is expected to occur during phasic dopaminergic signalling, when midbrain dopaminergic neurons generate a transient (0.5 s) burst of APs in response to a salient event.

Eye contact, a fundamental building block of social behavior, engages single unit activity in the monkey amygdala

In primates, the meaningful use of facial signals and eye contact is a prerequisite for normal social behavior. Just by looking at the face of another monkey, an individual can determine its age, sex, dominance status, health, etc. Facial expressions are useful to determine the emotional state and possible intentions of others. Eye contact facilitates affiliative behaviors such as facial mimicry in the context of mother-infant interactions, but also conveys threats and dominance status in adult-adult interactions. The neural circuitry that underlies these behaviors is largely unknown. One goal of our research is to determine the role of the primate amygdala in basic aspects of social communication that involve looking at the eyes of other individuals. To achieve this goal we developed an experimental paradigm that elicits reliably and reproducibly several aspects of social behavior including eye contact, facial mimicry, and gaze following [1]. Additionally, we recordeded single unit activity from the monkey amygdala to determine which of these social components (if any) reliably induce neural responses. Species-specific and socially meaningful behaviors were elicited using naturalistic videos that depicted unknown monkeys displaying neutral, agonistic, or affiliative behaviors. Each video contained segments of displays when the movie monkey's eye gaze was directed toward the viewer monkey. The eye movements of the viewer monkey were co-registered with each movie frame and with multiple channels of single unit activity recorded from the amygdala. We found that 23/123 (19%) of neurons in the amygdala discharged selectively or exclusively when the viewer monkey looked at the eyes of the movie monkey (Figure ​(Figure1).1). These neurons had a response latency of 100-150ms from the start of fixation on the movie monkey’s eyes. They exhibited either excitatory (13/23, 57%) or inhibitory responses to looking at the eyes, and either no response (or a polar opposite response) to looking at other parts of the face or body. Higher responses occurred when the movie monkey's eye gaze was directed at the viewer (eye contact) than for averted gaze. A subset of neurons showed phasic responses indicating that eye contact had been established, whereas others showed tonic, sustained changes in firing for the entire duration of the fixation. We conclude that the amygdala is likely an important center for the elaboration of a fundamental building block of social behavior: looking at the eyes of others and establishing eye contact. Figure 1 Rasterplot and peristimulus time histogram of a single unit recorded from the monkey amygdala. This neuron had an increased firing rate that was maintained for the entire duration that the viewer monkey fixated on the eyes of the movie monkey (left panel). ...

Statistical Deconvolution for Superresolution Fluorescence Microscopy

Superresolution microscopy techniques based on the sequential activation of fluorophores can achieve image resolution of ∼10 nm but require a sparse distribution of simultaneously activated fluorophores in the field of view. Image analysis procedures for this approach typically discard data from crowded molecules with overlapping images, wasting valuable image information that is only partly degraded by overlap. A data analysis method that exploits all available fluorescence data, regardless of overlap, could increase the number of molecules processed per frame and thereby accelerate superresolution imaging speed, enabling the study of fast, dynamic biological processes. Here, we present a computational method, referred to as deconvolution-STORM (deconSTORM), which uses iterative image deconvolution in place of single- or multiemitter localization to estimate the sample. DeconSTORM approximates the maximum likelihood sample estimate under a realistic statistical model of fluorescence microscopy movies comprising numerous frames. The model incorporates Poisson-distributed photon-detection noise, the sparse spatial distribution of activated fluorophores, and temporal correlations between consecutive movie frames arising from intermittent fluorophore activation. We first quantitatively validated this approach with simulated fluorescence data and showed that deconSTORM accurately estimates superresolution images even at high densities of activated fluorophores where analysis by single- or multiemitter localization methods fails. We then applied the method to experimental data of cellular structures and demonstrated that deconSTORM enables an approximately fivefold or greater increase in imaging speed by allowing a higher density of activated fluorophores/frame.

Comparison of Retrospectively Self-Gated and Prospectively Triggered FLASH Sequences for Cine Imaging of the Aorta in Mice at 9.4 Tesla

A critical problem in cardiovascular MRI in small rodents is adjusting the sequence acquisition to the high heart and respiratory rates. The aim of this study was to compare a retrospectively self-gated fast low angle shot navigator (RSG-FLASH) sequence with a conventional prospectively triggered (PT-FLASH) sequence for cine imaging of the ascending aorta in mice at 9.4 T. Ten C57/BL6 mice were examined with a horizontal bore 9.4 Tesla MRI animal scanner using a dedicated 2 × 2 phased-array surface coil. We acquired a RSG-FLASH sequence (RSG-FLASH sequences (repetition time (TR) / echo time (TE) = 6.5/2.5 ms, flip angle (FA) = 10 degrees, field of view (FOV) = 2 × 2 cm, matrix = 384 × 384, slice thickness = 1 mm, 25 movie frames) perpendicular to the ascending aorta using the IntraGate technique. At the same position, we performed a PT-FLASH sequence (TR/TE = 6.5/2.1 ms, FA = 10 degrees, FOV = 2 × 2 cm, matrix = 384 × 384, slice thickness = 1 mm) in which the maximum number of movie frames had to be adjusted to the interval between two R-peaks (RR interval) of the electrocardiogram (ECG) with: number of frames = RR interval / TR." Cross-sectional vessel areas at end-systole (AES) and end-diastole (AED) were measured to determine the aortic strain (ΔA = (AES-AED)/AED). Two blinded readers rated the sequences for presence of flow and trigger artifacts and their influence on the depiction of the blood/vessel-wall interface. Irregularities in displaying the cardiac cycle and the overall suitability of the sequence for aortic strain evaluation were assessed using a 5-level ordinal scale. Statistical differences were analyzed using Student t test and Wilcoxon signed rank test (P < 0.05). Intra- and interobserver variability was evaluated using Bland-Altman analyses. No significant differences were noted between techniques regarding the measured vessel areas (AED: P = 0.07, AES: P = 0.34), ΔA: P = 0.1). Similarly, there were no significant differences in heart (P = 0.06) and respiratory (P = 0.24) rates. The acquisition time for RSG-FLASH sequence was significantly shorter (P = 0.04). Significantly fewer flow and trigger artifacts were noted by both readers with the RSG-FLASH sequence. Likewise, both readers considered the RSG-FLASH sequence to be superior for depiction of the blood/vessel-wall interface. The RSG-FLASH sequence was also rated superior regarding irregularities in displaying the cardiac cycle and in terms of overall suitability for evaluation of AED, AES, and aortic strain (P < 0.05 each). RSG-FLASH is preferable for cine imaging of the aorta. It provides the same quantitative data as PT-FLASH cine imaging but is less prone to flow and trigger artifacts. RSG-FLASH permits more homogeneous depiction of the cardiac cycle and is faster than the PT-FLASH sequence. PT-FLASH is more prone to misregistration of the respiratory cycle or the ECG by the external monitoring device used for acquisition. This effect may be even more pronounced in animals with disease models that are less stable in terms of heart and respiration rate during anesthesia.

KOFIC 3D 제작 프로젝트 연구 -'놀이동산에 또 놀러 와요, 엄마'를 중심으로-

Andre Bazin called movie frame as the window open to world. This expression is close to realization through 3D films. The `Avatar` released in 2009 was a new turning point for 3D films. Nowadays theory and information about 3D films is overflowed. It is necessary to find practices and to accumulate data useful in production of 3D films. There are several ways of working to achieve high quality 3D films. In any way that`s chosen, there are priorities to be considered to create well-balanced 3D films. The aim of this article is to review primary considerations in film-making and share technical issues experienced during production of Let`s go to amusement park again, Mom. Because current practical knowledge in making 3D film is shallow, this article will offer a possible reference for further research.

Beam-induced motion of vitrified specimen on holey carbon film

The contrast observed in images of frozen-hydrated biological specimens prepared for electron cryo-microscopy falls significantly short of theoretical predictions. In addition to limits imposed by the current instrumentation, it is widely acknowledged that motion of the specimen during its exposure to the electron beam leads to significant blurring in the recorded images. We have studied the amount and direction of motion of virus particles suspended in thin vitrified ice layers across holes in perforated carbon films using exposure series. Our data show that the particle motion is correlated within patches of 0.3-0.5 μm, indicating that the whole ice layer is moving in a drum-like motion, with accompanying particle rotations of up to a few degrees. Support films with smaller holes, as well as lower electron dose rates tend to reduce beam-induced specimen motion, consistent with a mechanical effect. Finally, analysis of movies showing changes in the specimen during beam exposure show that the specimen moves significantly more at the start of an exposure than towards its end. We show how alignment and averaging of movie frames can be used to restore high-resolution detail in images affected by beam-induced motion.

Complete Lateral and Angular Diffusion and Protein-Protein Interaction Description of a Membrane Protein

Membrane-mediated protein-protein and protein-lipid interactions, membrane protein localization, and related dynamics, modulate membrane protein function. So far membrane structure and dynamics could not be studied altogether lacking the technique that analyzes unlabelled proteins at submolecular lateral and high temporal resolution. Here we used high-speed atomic force microscopy (HS-AFM) to characterize the lateral and angular movements and interactions of unlabelled OmpF. OmpF distribution emerges from diffusion-limited aggregation, maximizing surface coverage and providing a multitude of local environments and contacts. Protein motion scales roughly with membrane crowding. However molecules display individuality of diffusion behavior ranging from fast moving (∼400nm2/s) to immobile molecules trapped by favorable protein-protein associations. We derive the complete molecular interaction probability landscape that we compare with coarse-grained molecular dynamics simulation of the membrane protein interaction. HS-AFM may open a novel research avenue that bridges structure of individual membrane proteins and supramolecular membrane architecture.HS-AFM movie frames (frame rate 477 ms) showing the motion of OmpF trimers in the membrane. Right: Experimental interaction potential mapView Large Image | View Hi-Res Image | Download PowerPoint Slide

Direct Observation of Junctional Microdomain Assembly

Junctional microdomains are specialized membrane protein assemblies in eye lens fiber cell membranes. They are constituted of lens-specific aquaporin-0 (AQP0) and connexins (Cx) that assure nutrition and adhesion of lens cells, mutation or absence of these proteins lead to cataract. In a more general term, junctional microdomains are paradigm for membrane protein segregation in functional assemblies in a membrane with non-random superstructure. Here we use high-speed atomic force microscopy (HS-AFM) and Monte Carlo simulation to analyze the dynamics and assembly of membrane proteins in junctional microdomains. We report cooperative adhesion of head-to-head attached AQP0 and Cx in junctional microdomains. Furthermore we evidence that enthalpy energy gain of protein association dominates entropy leading to square shaped AQP0 arrays of finite size segregated from and edged by connexins. The power of HS-AFM sample manipulation and imaging structure and dynamics at single-molecule resolution is highlighted opening a new avenue of membrane research watching the behavior of unlabelled molecules while also seeing their molecular environment.HS-AFM movie frames showing native AQP0 arrays assembling (A-E) and disassembling (E-H).View Large Image | View Hi-Res Image | Download PowerPoint Slide

Chronic imaging of cortical sensory map dynamics using a genetically encoded calcium indicator

In vivo optical imaging can reveal the dynamics of large-scale cortical activity, but methods for chronic recording are limited. Here we present a technique for long-term investigation of cortical map dynamics using wide-field ratiometric fluorescence imaging of the genetically encoded calcium indicator (GECI) Yellow Cameleon 3.60. We find that wide-field GECI signals report sensory-evoked activity in anaesthetized mouse somatosensory cortex with high sensitivity and spatiotemporal precision, and furthermore, can be measured repeatedly in separate imaging sessions over multiple weeks. This method opens new possibilities for the longitudinal study of stability and plasticity of cortical sensory representations.