Optically gated beating-heart imaging

The constant motion of the beating heart presents an obstacle to clear optical imaging, especially 3D imaging, in small animals where direct optical imaging would otherwise be possible. Gating techniques exploit the periodic motion of the heart to computationally "freeze" this movement and overcome motion artefacts. Optically gated imaging represents a recent development of this, where image analysis is used to synchronize acquisition with the heartbeat in a completely non-invasive manner. This article will explain the concept of optical gating, discuss a range of different implementation strategies and their strengths and weaknesses. Finally we will illustrate the usefulness of the technique by discussing applications where optical gating has facilitated novel biological findings by allowing 3D in vivo imaging of cardiac myocytes in their natural environment of the beating heart

Simultaneous interpreting : walking a tightrope

Several phenomena associated with the differences in the performance of novice interpreters and semi-professionals have been discussed in the paper. Particular emphasis was placed on the occurrence of imported cognitive load which strongly influenced the performance of the subjects also in places where no intrinsic difficulty had been detected. Nevertheless, too little evidence was provided to establish a more detailed pattern of imported cognitive load, which was due to the limited number of participants in the study. It would be possible to obtain more detailed data and comments from the participants by means of interviews conducted individually with the participants. It would allow asking detailed questions to the participants, which might be a more reliable method than the immediate retrospective accounts. Moreover, in the present study such variables as gender differences, age differences and the possible influence of other foreign languages were not taken into account. Perhaps these variables might shed some light on the issue of the management of cognitive resources. Also, the corpus gathered for the present study may be used for the investigation of other aspects of the SI performance

Direct Sequence Spread Spectrum Acquisition Design

Spread spectrum communication techniques are utilized to provide transmission of signals which have anti-jamming properties, a low probability of being intercepted, and can support a multiple-access system by servicing simultaneously a number of channels. This thesis concentrates on the receiver acquisition problem of a transmitted signal which is the output of a spread spectrum communication system. The acquisition requirements of a spread spectrum system and also the general approaches to the problem of “active and passive correlation” are discussed. A unique general purpose all-digital acquisition hardware design is developed and described to the schematic level of detail, where specific parts and their interconnections are illustrated. The hardware design development and analysis workstation used is developed by the Daisy Corporation

Parisuhdehistoriat ja niiden yhteys lasten määrään : sekvenssianalyysi 1924-1966 syntyneistä naisista

Previous studies have indicated that short cohabitation spells are associated with childlessness. However, there is little detailed knowledge of relationship trajectories and their implications to the completed number of children other than childlessness in Finland. In addition, previous studies mainly focused on residential relationships, and non-residential relationships were seldom studied. This study provides an overview of different relationship trajectories for women born in 1924-1966 and explores the connections between the complete trajectories and the number of biological children. The relationship trajectories were established using longitudinal retrospective data. This study utilized sequence analysis that visualizes the relationship stages on the life course forming a relationship trajectory. The trajectories were clustered to reveal prominent patterns in the data, and the connection between the clusters and the number of children was explored. Additionally, the changes that occurred in the different cohorts were investigated to reveal historical patterns. The results indicate that most women born between 1924 and 1966 dated, cohabitated, and married before the age of 30 and stayed with the same partner, resulting in a steady pattern of 2 or more children. If a divorce occurred, the number of children depended on whether the individual married again. Long-term cohabitation was connected with a lower number of children. Lack or postponement of long-term relationships often resulted in a significantly smaller number of children. The connection between the first relationship and the first marriage got weaker over time, and the trajectories marked by more complex partnership histories and long-term cohabitation increased. Relationship trajectories shape childbearing outcomes in distinct ways. The study increases knowledge about the processes of relationships and childbearing in the changing landscape of family formation

Temporal Interpolation via Motion Field Prediction

Navigated 2D multi-slice dynamic Magnetic Resonance (MR) imaging enables high contrast 4D MR imaging during free breathing and provides in-vivo observations for treatment planning and guidance. Navigator slices are vital for retrospective stacking of 2D data slices in this method. However, they also prolong the acquisition sessions. Temporal interpolation of navigator slices an be used to reduce the number of navigator acquisitions without degrading specificity in stacking. In this work, we propose a convolutional neural network (CNN) based method for temporal interpolation via motion field prediction. The proposed formulation incorporates the prior knowledge that a motion field underlies changes in the image intensities over time. Previous approaches that interpolate directly in the intensity space are prone to produce blurry images or even remove structures in the images. Our method avoids such problems and faithfully preserves the information in the image. Further, an important advantage of our formulation is that it provides an unsupervised estimation of bi-directional motion fields. We show that these motion fields can be used to halve the number of registrations required during 4D reconstruction, thus substantially reducing the reconstruction time.Comment: Submitted to 1st Conference on Medical Imaging with Deep Learning (MIDL 2018), Amsterdam, The Netherland

Four-dimensional cardiac imaging in living embryos via postacquisition synchronization of nongated slice sequences

Being able to acquire, visualize, and analyze 3D time series (4D data) from living embryos makes it possible to understand complex dynamic movements at early stages of embryonic development. Despite recent technological breakthroughs in 2D dynamic imaging, confocal microscopes remain quite slow at capturing optical sections at successive depths. However, when the studied motion is periodic— such as for a beating heart—a way to circumvent this problem is to acquire, successively, sets of 2D+time slice sequences at increasing depths over at least one time period and later rearrange them to recover a 3D+time sequence. In other imaging modalities at macroscopic scales, external gating signals, e.g., an electro-cardiogram, have been used to achieve proper synchronization. Since gating signals are either unavailable or cumbersome to acquire in microscopic organisms, we have developed a procedure to reconstruct volumes based solely on the information contained in the image sequences. The central part of the algorithm is a least-squares minimization of an objective criterion that depends on the similarity between the data from neighboring depths. Owing to a wavelet-based multiresolution approach, our method is robust to common confocal microscopy artifacts. We validate the procedure on both simulated data and in vivo measurements from living zebrafish embryos

On the behaviours produced by instruction sequences under execution

We study several aspects of the behaviours produced by instruction sequences under execution in the setting of the algebraic theory of processes known as ACP. We use ACP to describe the behaviours produced by instruction sequences under execution and to describe two protocols implementing these behaviours in the case where the processing of instructions takes place remotely. We also show that all finite-state behaviours considered in ACP can be produced by instruction sequences under execution.Comment: 36 pages, consolidates material from arXiv:0811.0436 [cs.PL], arXiv:0902.2859 [cs.PL], and arXiv:0905.2257 [cs.PL]; abstract and introduction rewritten, examples and proofs adde