Frame Time Research Articles

Leading with digital in an age of supercomplexity

Across education all aspects of practice, including teaching, research, public engagement and administration, are taking place increasingly against a digital backdrop. As digital becomes widely recognized as both key element of enabling institutional change, and creating challenges for all institutional activities, Jisc have developed a digital leaders course to engage delegates with their own digital practices, and help them in applying tools and methods to both support their own development and leverage digital in their organization. This short paper reports on the initial courses and some of the delegate reactions, drivers to participate in the course and it also outlines the structure of the course and the underpinning approaches taken. Barnett’s definition of supercomplexity, a time of uncertainty, unpredictability, challenge and change frames the nature of the education landscape faced by institutions well. However, through the digital leaders course, Jisc seeks to both frame the challenges created by digital, and also show digital as providing the capacity and capabilities to respond to supercomplexity.

Double-level bone transport for large post-traumatic tibial bone defects: a single centre experience of sixteen cases.

The aim of this study was to evaluate the clinical and functional outcomes of patients with large post-traumatic tibial bone defects managed by double-level bone transport using the Ilizarov technique. We retrospectively reviewed 16 patients of 39.1years (range, 16.0-65.0years). The bone defects averaged 10.9±3.8cm (range: 6.0cm-20.0cm) after radical resection and were managed by double-level bone transport. Bone and functional results were evaluated according to the ASAMI criteria. The mean duration of follow-up after frame removal was 29.5±1.8months (range, 12.0-36.0months). All patients achieved complete union in both the regenerates and the docking site and eradication of infection. The mean bone transport time was 55.6±23.7days (range, 30.0-125.0days). The mean external fixation time was 12.0±3.9months (range, 5.0-18.0months), and the mean external fixation index was 1.1±0.3months/cm (rang, 0.8-2.0months/cm). The bone results were excellent in ten patients and poor in six patients. The functional results were excellent in 12 patients and good in four patients. Double-level bone transport is a safe, reliable, and successful method for large post-traumatic tibial bone defects. Furthermore, this technique can reduce bone transport time, time in frame, and total treatment time in one stage.

Motion-Blur-Free High-Speed Video Shooting Using a Resonant Mirror.

This study proposes a novel concept of actuator-driven frame-by-frame intermittent tracking for motion-blur-free video shooting of fast-moving objects. The camera frame and shutter timings are controlled for motion blur reduction in synchronization with a free-vibration-type actuator vibrating with a large amplitude at hundreds of hertz so that motion blur can be significantly reduced in free-viewpoint high-frame-rate video shooting for fast-moving objects by deriving the maximum performance of the actuator. We develop a prototype of a motion-blur-free video shooting system by implementing our frame-by-frame intermittent tracking algorithm on a high-speed video camera system with a resonant mirror vibrating at 750 Hz. It can capture 1024 × 1024 images of fast-moving objects at 750 fps with an exposure time of 0.33 ms without motion blur. Several experimental results for fast-moving objects verify that our proposed method can reduce image degradation from motion blur without decreasing the camera exposure time.

Human action recognition based on kinematic similarity in real time.

Human action recognition using 3D pose data has gained a growing interest in the field of computer robotic interfaces and pattern recognition since the availability of hardware to capture human pose. In this paper, we propose a fast, simple, and powerful method of human action recognition based on human kinematic similarity. The key to this method is that the action descriptor consists of joints position, angular velocity and angular acceleration, which can meet the different individual sizes and eliminate the complex normalization. The angular parameters of joints within a short sliding time window (approximately 5 frames) around the current frame are used to express each pose frame of human action sequence. Moreover, three modified KNN (k-nearest-neighbors algorithm) classifiers are employed in our method: one for achieving the confidence of every frame in the training step, one for estimating the frame label of each descriptor, and one for classifying actions. Additional estimating of the frame’s time label makes it possible to address single input frames. This approach can be used on difficult, unsegmented sequences. The proposed method is efficient and can be run in real time. The research shows that many public datasets are irregularly segmented, and a simple method is provided to regularize the datasets. The approach is tested on some challenging datasets such as MSR-Action3D, MSRDailyActivity3D, and UTD-MHAD. The results indicate our method achieves a higher accuracy.

Segmental Bone Loss Reconstruction Using Ring Fixation.

Ring fixation is a powerful tool in the treatment of bone defects. The ability to create high-quality, biologically normal new bone of even massive proportions using distraction osteogenesis is a major reason for its success. In addition, ring fixation provides the ability to limit the risk of deep infection, improves flexibility in limb length control and alignment, and increases soft tissue coverage options. The drawbacks of ring fixation include long frame times, pin problems, risk of joint contractures, and difficult usage in areas with a large soft tissue envelope such as the thigh. Significant advancements such as hydroxyapatite coated pins, internal cable transport, multifocal transport, and combined techniques with internal fixation have helped increase the effectiveness of ring fixator use by minimizing many of the drawbacks. At present, ring fixation provides the most effective means of treatment for large bone defects in many clinic situations.

Optimized Error Probability for Weighted Collaborative Spectrum Sensing in Time- and Energy-Limited Cognitive Radio Networks

In this paper, a collaborative energy-harvesting cognitive radio (CR) network is considered such that the transmitter of the secondary user (SU) is allowed to harvest signal energy of the primary user (PU) when the presence of the PU is detected. The harvested energy is converted to electrical power in order to supply the sensing and transmission energy of SUs. The time frame (time slot) is divided into two phases allocated to sensing (divided into two durations: spectrum sensing and results reporting) and transmission, respectively. The time spanned by the results reporting duration depends on the number of collaborative sensing users, while the time spent on spectrum sensing duration controls the number of sensing samples. A constrained convex optimization problem of the overall probability of error is formulated incorporating constraints on time and energy resources along with PU interference protection presented as a threshold on probability of collision. We use a soft decision rule scheme while considering two energy harvesting scenarios namely, energy surplus and energy deficit. In each scenario, the convexity of the optimization problem is established analytically and the global optimal solution is obtained. Simulation results are provided to demonstrate the impact of the different parameters on the overall system performance as well as to verify the deduced analytical results.

Spatially encoded fast single-molecule fluorescence spectroscopy with full field-of-view

We report a simple single-molecule fluorescence imaging method that increases the temporal resolution of any type of array detector by >5-fold with full field-of-view. We spread single-molecule spots to adjacent pixels by rotating a mirror in the detection path during the exposure time of a single frame, which encodes temporal information into the spatial domain. Our approach allowed us to monitor fast blinking of an organic dye, the dissociation kinetics of very short DNA and conformational changes of biomolecules with much improved temporal resolution than the conventional method. Our technique is useful when a large field-of-view is required, for example, in the case of weakly interacting biomolecules or cellular imaging.

Compression of CT sinogram data by decimation in the view direction.

In clinical computed tomography (CT), the image data is acquired during continuous rotation. If the time during which the signal is integrated (the frame time) is too long, the data is blurred in the view direction (i.e., azimuthal blur). This can be overcome by having a high angular sampling rate, but for systems with limited bandwidth, the increased amount of data can be a problem. In this paper, we evaluate the benefit of maintaining a high angular sampling rate on the CT gantry and performing a decimation (digital low-pass filtration followed by a downsampling) in the view direction before the bottleneck of the data transfer chain. A theoretical evaluation of the effects of the decimation is presented and the implementation of the digital filter is discussed. The compression scheme is evaluated on image data of a CATPHAN® 504 phantom and a human skull phantom. It is shown that digital decimation can be used to compress data before read-out with more remaining data fidelity compared to having longer frame times. Specifically, the method is shown to preserve the detail in the reconstruction of the CATPHAN resolution patterns and the human skull phantom. It is also demonstrated that the method can be used to prevent aliasing artifacts. Decimation in the view direction is presented as an alternative to increasing the frame time for CT systems with limited bandwidth of the data read-out. The method can be used to eitherremove aliasing artifacts or preserve spatial resolution. The proposed compression scheme can be implemented on the CT gantry and thus reduce the bandwidth requirements on the data transfer.

Quantification accuracy of neuro-oncology PET data as a function of emission scan duration in PET/MR compared to PET/CT

ObjectivesTo evaluate and compare the effect of reduced acquisition time, as a surrogate of injected activity, on the PET quantification accuracy in PET/CT and PET/MR imaging. MethodsTwenty min 18F-FDG phantom measurements and 10min 18F-FET brain scans were acquired in a Biograph-True-Point-True-View PET/CT (n=8) and a Biograph mMR PET/MR (n=16). Listmode data were repeatedly split into frames of 1min to 10min length and reconstructed using two different reconstruction settings of a 3D-OSEM algorithm: with post-filtering (“OSEM”), and without post-filtering but with resolution recovery (“PSF”). Recovery coefficients (RCmax, RCA50) and standard uptake values (SUVmax, SUVA50) were evaluated. ResultsRCmax (phantom) and SUVmax (patients) increased significantly when reducing the frame duration. Significantly lower deviations were observed for RCA50 and SUVA50, respectively, making them more appropriate to compare PET studies at different number of counts. No statistical significant differences were observed when using post-filtering and reducing the frame time to 4min (RCA50, reference 20min, phantom) and to 3min (SUVA50, reference 10min, patients). ConclusionsFor hybrid aminoacid brain imaging, frame duration (or injected activity) can potentially be reduced to 30% of the standard used in clinical routine without significant changes on the quantification accuracy of the PET images if adequate reconstruction settings and quantitative measures are used. Frame times below 4min in the NEMA phantom are not advisable to obtain quantitative and reproducible measures.

High-order integration scheme for relativistic charged particle motion in magnetized plasmas with volume preserving properties

A numerical algorithm for solving full gyro orbit of relativistic charged particle motion in magnetized plasmas is presented. The algorithm developed here achieves the following features simultaneously. (1) The time advancement is explicit, and (2) the integration is performed with respect to the observation time in a laboratory frame. (3) It is suitable for accurate long time integration with its volume preserving properties in the phase space. (4) The algorithm can properly treat the E×B drift velocity in electromagnetic fields for large relativistic factors, and (5) can be extended to arbitrary high orders with the aid of symmetric composition methods. Because our algorithm is formulated in the Lorentz covariant form, explicit conservation of the Minkowski norm is not assumed. Nevertheless, no secular growth of the numerical errors in the norm does occur, and its influence can be minimized up to the levels of round-off errors when a high-order scheme is applied. Numerical results are compared with explicit and implicit Runge–Kutta methods. The numerical accuracy and the computational efficiency are discussed for long time integration in toroidal magnetic field configuration.

A Network-Aware Encoding Rate Control Algorithm for Real-Time Up-Streaming Video Services

Real-time personal broadcasting and video social network services on which a user’s mobile device serves as the content provider have received a considerable amount of attention. This letter presents an up-streaming video service in which a mobile device records and encodes video streams on the spot and transmits them to a receiver through an uplink interface. Unlike existing streaming services, the receiver in this service receives and plays video streams in real time without buffering them. Considering the requirements of real-time characteristics and frequent network state changes, this letter proposes a new encoding rate control algorithm for an up-streaming video service based on the estimated network condition. The sender estimates the network status based on the average inter-arrival time of video frames periodically measured and transmitted by the receiver. The network-aware encoding rate control algorithm was implemented on a mobile device running the Android OS. The effectiveness of the algorithm was proved through experiments performed on a commercial LTE network and in an ordinary office WiFi environment.

Hexapod Frame Stacked Transport for Tibial Infected Nonunions With Bone Loss: Analysis of Use of Adjunctive Stability.

The stacked hexapod bone transport technique is an effective treatment for infected tibial nonunions with bone loss. The purpose of this study was to evaluate the patients' risk factors and timing for requiring adjunctive stabilization. Retrospective cohort study. Level 1 trauma center. Seventy-five patients with infected posttraumatic nonunions of the tibia. Resection of nonunion with application of stacked hexapod frame for bone transport. Parameters measured included age, sex, diabetes, smoking, use of a free flap, bone defect size, length in frame, external fixation index, and direction of lengthening. Outcomes recorded: removal of frame, below knee amputation, or adjunctive stability. Further analysis evaluated location of nonunion, timing of adjunctive stabilization, and type of fixation. The average patient age was 45.7 ± 12.5 years, 76% patients were men, 11% were diabetic, and 44% were smokers. Forty two percent had soft tissue defects that required a free flap. Thirty-eight patients had removal of frame, whereas 36 patients required adjunctive stability of the hexapod frame. Patient receiving adjunctive stabilization had a longer length of time in the hexapod frame (P = 0.026) and were more likely to require a free flap (P = 0.053). Ninety-three percent docking site nonunions occurred after the removal of the frame (P = 0.032); whereas 79% regenerate nonunions occurred before the hexapod frame was removed (P = 0.029). The use of a hexapod frame for the infected tibial nonunions with bone loss is an effective method for achieving union and eradicating infection in a difficult orthopaedic patient population. Use of adjunctive stabilization is a reasonable technique to address delayed regenerate and docking site nonunions. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

A training-based speech regeneration approach with cascading mapping models

Computational speech reconstruction algorithms have the ultimate aim of returning natural sounding speech to aphonic and dysphonic patients as well as those who can only whisper. In particular, individuals who have lost glottis function due to disease or surgery, retain the power of vocal tract modulation to some degree but they are unable to speak anything more than hoarse whispers without prosthetic aid. While whispering can be seen as a natural and secondary aspect of speech communications for most people, it becomes the primary mechanism of communications for those who have impaired voice production mechanisms, such as laryngectomees.In this paper, by considering the current limitations of speech reconstruction methods, a novel algorithm for converting whispers to normal speech is proposed and the efficiency of the algorithm is explored. The algorithm relies upon cascading mapping models and makes use of artificially generated whispers (called whisperised speech) to regenerate natural phonated speech from whispers. Using a training-based approach, the mapping models exploit whisperised speech to overcome frame to frame time alignment problems that are inherent in the speech reconstruction process. This algorithm effectively regenerates missing information in the conventional frameworks of phonated speech reconstruction, and is able to outperform the current state-of-the-art regeneration methods using both subjective and objective criteria.

A Driving Method of Pixel Circuit Using a-IGZO TFT for Suppression of Threshold Voltage Shift in AMLED Displays

A driving method of pixel circuit using amorphous indium gallium zinc oxide (a-IGZO) thin-film transistor (TFT) is proposed to improve the image quality of active matrix light-emitting diode displays. The proposed pixel circuit employs a diode-connected structure to compensate for variation in threshold voltage ( $V_{\sf {th}}$ ) of the a-IGZO TFT. In addition, the proposed driving method adopts negative bias annealing to suppress the $V_{\sf {th}}$ shift. The annealing time is optimized based on the experimental observation of the minimum $V_{\sf {th}}$ shift. After a stress time of 30000 s, the measurement results show that the $V_{\sf {th}}$ shift is reduced by 29.6%, using an optimized annealing time of 5% of one frame time. In addition, the maximum deviation in the emission current using the proposed driving method was measured to be less than 4.32% after a stress time of 30000 s.

A technical note on variable inter-frame interval as a cause of non-physiological experimental artefacts in ultrasound.

Ultrasound (US) imaging is a well-recognized technique for the study of static tissues but its suitability for studying tissue dynamics depends upon accurate frame time information, which may not always be available to users. Here we present methods to quantify the inter-frame interval (IFI) variability, and evaluate different procedures for collecting temporal information from two US-imaging devices. The devices tested exhibited variable IFIs that could only be confirmed by direct measures of timing signals, available by means of electrical signals (triggers) and/or temporal information contained in the software used for the US data collection. Interpolating frame-by-frame measures of dynamic changes within image sequences using individual IFI values provided improved synchronization between measures of skeletal muscle movement and activation; validating US as a valuable technique for the study of musculoskeletal tissue dynamics, when correctly implemented.

Solid-state NMR studies for the development of non-woven biomaterials based on silk fibroin and polyurethane

Silk fibroin (SF) possesses several characteristics that are favorable for tissue engineering. However, the mechanical properties must be modified in some cases. For instance, soft tissues such as those of the circulatory system are more elastic than tissue-engineered materials. The development of polymer blends is a simple method with the potential to provide materials with extended useful properties. In this study, we developed a non-woven SF and thermoplastic polyurethane-blend sheet from a polymer solution. The structure and miscibility of the blend sheet was evaluated using solid-state nuclear magnetic resonance (NMR) methods. In the 13C cross-polarization and magic angle spinning NMR spectra, no peak shift was observed between the pure and blended samples. The miscibility of the sample was investigated using proton spin-lattice relaxation times in the laboratory frame (T1H). The T1H measurement clearly revealed that the molecular chains of SF and Pellethane exist in close proximity of several tens of nanometers. The development of polymer blends is a simple method with the potential to provide materials with extended useful properties. Here, the SF and Pellethane were observed to be highly miscible with each other even though SF maintained the strong β-sheet crystal structure. This result suggests that SF/Pellethane-blended sheets possess strength that is derived from SF and elasticity that is derived from Pellethane. Therefore, this blended sheet should be a good medical material for soft tissue engineering.

Early-Dynamic Positron Emission Tomography (PET)/Computed Tomography and PET Angiography for Endoleak Detection After Endovascular Aneurysm Repair

Purpose: To propose a positron emission tomography (PET)/computed tomography (CT) protocol including early-dynamic and late-phase acquisitions to evaluate graft patency and aneurysm diameter, detect endoleaks, and rule out graft or vessel wall inflammation after endovascular aneurysm repair (EVAR) in one examination without intravenous contrast medium. Technique: Early-dynamic PET/CT of the endovascular prosthesis is performed for 180 seconds immediately after intravenous injection of F-18-fluorodeoxyglucose. Data are reconstructed in variable time frames (time periods after tracer injection) to visualize the arterial anatomy and are displayed as PET angiography or fused with CT images. Images are evaluated in view of vascular abnormalities, graft configuration, and tracer accumulation in the aneurysm sac. Whole-body PET/CT is performed 90 to 120 minutes after tracer injection. Conclusion: This protocol for early-dynamic PET/CT and PET angiography has the potential to evaluate vascular diseases, including the diagnosis of complications after endovascular procedures.

Corrections to the Thomson cross section caused by relativistic effects and by the presence of the drift velocity of a classical charged particle in the field of a monochromatic plane wave

An approach to the solution of the relativistic problem of the motion of a classical charged particle in the field of a monochromatic plane wave with an arbitrary polarization (linear, circular, or elliptic) is proposed. It is based on the analysis of the 4-vector equation of motion of the charged particle together with the 4-vector and tensor equations for the components of the electromagnetic field tensor of a monochromatic plane wave. This approach provides analytical expressions for the time-averaged square of the 4-acceleration of the charge, as well as for the averaged values of any quantities periodic in the time of the reference frame. Expressions for the integral power of scattered radiation, which is proportional to the time-averaged square of the 4-acceleration of the charge, and for the integral scattering cross section, which is the ratio of the power of scattered radiation to the intensity of incident radiation, are obtained for an arbitrary inertial reference frame. An expression for the scattering cross section, which coincides with the known results at the circular and linear polarizations of the incident waves and describes the case of elliptic polarization of the incident wave, is obtained for the reference frame where the charged particle is on average at rest. An expression for the scattering cross section including relativistic effects and the nonzero drift velocity of a particle in this system is obtained for the laboratory reference frame, where the initial velocity of the charged particle is zero. In the case of the circular polarization of the incident wave, the scattering cross section in the laboratory frame is equal to the Thompson cross section.

Utilizing residual sensing slots to enhance energy efficiency of opportunistic cognitive radio networks

Abstract In Broadband Communications (BBC), terms like “Green Communication (GC)”, “Energy Efficiency (EE)”, and “Opportunistic Cognitive Radio (OCR)” are pursuing methods for saving energy consumption while accomplishing communications. Good implementations of these terms/concepts contribute in reducing pollution and preserve nature resources. Forthcoming mobile generations will face many tradeoffs between EE considerations versus system performance parameters especially throughput. In a multi-channel OCR system, the Secondary User (SU) senses some selected candidate primary channels based on a “belief” concept. This belief state represents the occupancy/vacancy state of the primary channel and is deduced via a Partial Observation Markov Decision Process (POMDP). Within the OCR transmission frame, a fixed time-period at the beginning of this frame is dedicated for sensing multi primary channels. The SU performs the sensing needed to explore the state of occupancy/vacancy/fading of primary channels -within the sensing period- by dedicating a sensing slot for sensing each primary channel, then, SU updates its channel state belief accordingly. SU may not find it necessary to continue sensing more channels -using more sensing slots- in case of “low belief”, “bad CSI”, “highly believed to be occupied”, or even “sleep” if no candidate channels exist. This will lead to residual (not used) sensing slots which will be a wasted time in the frame time interval. This paper proposes an enhanced algorithm (to a previous work Feng and Gan, 2015) where these unused sensing slots are utilized to enhance the system EE. This is done by manipulating extended variable time induced from using these residual slots to extend the available transmission time. This induced variable time will increase throughput while keeping sensing energy. The metric used in this work is the Normalized Energy Efficiency (NEE) which is in consistence with many research directions in this field. In Feng and Gan (2015), the obtained NEE results reached ∼93% after about 20 transmitted frames, as well as, when 20 primary channels exist in the system. This work proposed an enhanced optimum and approximate algorithms that obtain as high as ∼135% of NEE after about 20 transmitted frames, they also obtained ∼228% using the optimum algorithm, or, ∼138% using the approximate algorithm when 20 primary channels are available.

Joint Block Sparse Signal Recovery Problem and Applications in LTE Cell Search

We consider the problem of jointly recovering block sparse signals that share the same support set, using multiple measurement vectors (MMVs). We consider the generalized MMV (GMMV) model wherein the different measurement vectors could have been obtained by using different sensing matrices. We study greedy- and convex-programming-based recovery algorithms and theoretically establish their support recovery guarantees. Our results present insights into how the correlation among block sparse signals plays a role in the recovery performance. Next, we consider the problem of cell search in heterogeneous cellular networks (HetNets). With the cell search process, the mobile terminal (MT) acquires synchronization parameters, such as frame timing, residual frequency offset, and the physical-layer identity of a base station (BS), suitable for its connection. In HetNets, due to the increased density of the BS, the MT may receive strong interference from several BSs in its neighborhood. We establish that the problem of cell search in HetNets can be solved by using the GMMV joint block sparse signal recovery framework. We numerically study the performance of the cell search algorithms proposed by using our framework and show that they perform significantly better than the successive interference cancelation algorithm that exists in the literature.