Search Results - (Author, Cooperation:H. Dana)

2015-02-14

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Animals ; *Biosensing Techniques ; Calcium/*analysis/metabolism ; Drosophila melanogaster ; Fluorescence ; *Genes, Immediate-Early ; Indicators and Reagents/analysis/metabolism ; Luminescent Proteins/genetics/*metabolism ; Mice ; Neural Pathways/*chemistry/cytology/physiology ; Neuronal Calcium-Sensor Proteins/genetics/*metabolism ; Protein Engineering ; Sensory Receptor Cells/*chemistry/physiology ; Staining and Labeling/*methods ; Zebrafish

article

1987

Vergleichsuntersuchung ; Vorschulpädagogik ; Klassengröße ; Lehrer-Schüler-Relation ; Unterrichtsmethode ; Unterrichtsmaterial ; Japan

Comparative education review, Bd. 31 (1987) H. 4, S. 533-549, 0010-4086

English

Literaturangaben, Tabellen 1

book

1989

Erziehung ; Kindergarten ; Vorschulpädagogik ; Interkultureller Vergleich ; Internationaler Vergleich ; China ; Japan ; USA

English

Literaturangaben 160, Register

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

A matched filter analysis has been developed to identify the amplitude and phase of magnetohydrodynamic modes in DIII-D tokamak plasmas using magnetic probe signals (δBp). As opposed to conventional Fourier spatial analysis of toroidally spaced probes, this analysis includes data from both toroidally and poloidally spaced magnetic probe arrays. Using additional probes both improves the statistics of the analysis and more importantly incorporates poloidal information into the mode analysis. The matched filter is a numeric filter that matches signals from the magnetic probes with numerically predicted signals for the mode. The numerical predictions are developed using EFIT equilibrium reconstruction data as input to the stability code GATO and the vacuum field code VACUUM. Changes is the plasma equilibrium that occur on the same time scale as the mode are taken into account by modeling simple matched filter vectors corresponding to changes in total plasma current, plus vertical and horizontal plasma shifts. The matched filter method works well when there is good understanding of a mode and good modeling of its structure. Matched filter analysis results for a fast growing ideal kink mode, where equilibrium change effects are minimal, show the effectiveness of this method. A slow growing resistive-wall mode (RWM) is also analyzed using the matched filter method. The method gives good results for identifying the amplitude and phase of the RWM but the simple equilibrium vectors are insufficient for complete elimination of equilibrium changes on this time scale. An analysis of the computational requirements of the scheme indicates that real-time application of the matched filter for RWM identification will be possible. © 2002 American Institute of Physics.

Electronic Resource

1524-4741

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1524-4741

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1524-4741

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Abstract: Image-guided core needle breast biopsy (IGCNBB) is an incisional biopsy technique that has been associated with tumor cell displacement. Theoretically tumor cell displacement may affect local recurrence rates in patients treated with breast-conserving therapy (BCT). We performed a study to determine if the biopsy method impacted local control rates following BCT. Patients with nonpalpable breast cancer (invasive and intraductal) diagnosed at our institution and treated with BCT between July 1993 and July 1996 were selected to provide a follow-up period in which the majority of local recurrences should be detected. Patients were divided into two groups based on their method of diagnosis. Group I patients were diagnosed by IGCNBB and group II patients were diagnosed by wire localized excisional breast biopsy (WLEBB). Factors potentially affecting local recurrence rates were retrospectively reviewed. Two hundred eleven patients were treated with BCT, 132 were diagnosed by IGCNBB and 79 by WLEBB. The two patient groups were similar when compared for prognostic factors and treatment. All patients' BCT included histologically negative margins. There were 4 (3.0%) local recurrences in Group I at a median follow-up of 44.4 months and 2 (2.5%) local recurrences in group II at a median follow-up of 50.1 months. This difference was not significant. Breast cancer patients diagnosed by IGCNBB can be treated by BCT with acceptable local control rates. Additional surveillance of our institutional experience and others' is mandatory to validate IGCNBB as the preferred biopsy method for nonpalpable mammographic abnormalities.

Electronic Resource

1540-8167

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Estimation of Entrainment Response. Introduction: Studies suggest that entrainment response (ER) of reentrant tachycardia to overdrive pacing can be estimated using signals from sites other than the paced site. Methods and Results: A formula for estimation of ER using remote sites against the difference between the postpacing interval (PPI) and tachycardia cycle length (TCL) determined solely from the paced site signal was validated in experimental data and using a simple two-dimensional cellular automata model of reentry. The model also was used to study the behavior and features of entrained surfaces, including the resetting of tachycardia phase by single premature paced stimuli. Experimental results from 1,484 remote sites in 115 pacing sequences showed the average of the median ER estimate error at each pacing site was −2 ± 5 msec , and the median ER estimate was within 10 msec of PPI–TCL for 94% of pacing sites. From simulation results, ER at the paced site was accurately estimated from 〉99.8% of 20,764 remote sites during pacing at 24 sites and three paced cycle lengths. Intervals measured from remote electrograms revealed whether the site was activated orthodromically or nonorthodromically during pacing, and results of simulations illustrated that the portion of the surface activated nonorthodromically during pacing increased with distance from the pacing site to the circuit. The phenomenon of nonorthodromic activation of reentrant circuits predicted by modeling was discernible in measurements taken from the animal model of reentrant tachycardia. Results also showed that, for single premature stimuli that penetrated the tachycardia circuit, phase reset of the tachycardia was linearly related to distance between the central obstacle and the paced site. Conclusion: The ER is a complex but predictable perturbation of the global activation sequence of reentrant tachycardias. This predictability allows calculations of the response from anywhere on the perturbed surface. These findings suggest new techniques for measurement of the ER, which may lend themselves to computer-based methods for accurate and rapid mapping of reentrant circuits.

Electronic Resource

1467-8640

Blackwell Publishing Journal Backfiles 1879-2005

Computer Science

The ability of a biological organism to visually track a perceptually significant feature in its environment has been argued to be an important feedback mechanism guiding locomotion. This paper analyzes the constraints available from the visual motion stimuli in the context of tracking. Our aim is to show that the act of tracking simplifies the decoding of egomotion parameters from motion stimuli. The constraints obtainable under tracking are utilized to analyze a possible egomotion decoding strategy for a binocular robot eye system, modeled after the human ocular tracking (smooth pursuit) mechanism. The main result of the paper is in the derivation of a closed-form solution of the egomotion parameters using feedback information concerning the movement of the tracking motors over time. The theoretical results are verified by experiments. We believe that the active tracking approach presented here is a more simple, practical, and manageable technique in a robot navigation setting, compared to passive methods.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

A one-dimensional (1D) fluid computer model for multiple ion species in an electron cyclotron resonance ion source (ECRIS) plasma has been developed. The ions species are assumed to be highly collisionally coupled and are treated using 1D fluid equations. The non-Maxwellian anisotropic electron distribution function is modeled by a 1D bounce-averaged Fokker–Planck code. ECR heating is included in the model as a quasilinear rf-diffusion term including relativistic detuning, rf pitch-angle scattering, and multiple resonance frequencies/locations. In a typical ECRIS, the electrons are very noncollisional and confined magnetically. The ions follow this electron confinement via the electrostatic potential. The 1D axial electrostatic potential profile predicted by the model shows an ion confining core electrostatic well as expected in ECRIS plasmas. Modeling results for the Argonne National Laboratory ECR-I ECRIS configuration are presented along with a discussion of the difficulties in benchmarking the model with Faraday cup measurements. © 2002 American Institute of Physics.

Electronic Resource

1365-2958

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

Despite over a century of research, tuberculosis remains a leading cause of infectious death worldwide. Faced with increasing rates of drug resistance, the identification of genes that are required for the growth of this organism should provide new targets for the design of antimycobacterial agents. Here, we describe the use of transposon site hybridization (TraSH) to comprehensively identify the genes required by the causative agent, Mycobacterium tuberculosis, for optimal growth. These genes include those that can be assigned to essential pathways as well as many of unknown function. The genes important for the growth of M. tuberculosis are largely conserved in the degenerate genome of the leprosy bacillus, Mycobacterium leprae, indicating that non-essential functions have been selectively lost since this bacterium diverged from other mycobacteria. In contrast, a surprisingly high proportion of these genes lack identifiable orthologues in other bacteria, suggesting that the minimal gene set required for survival varies greatly between organisms with different evolutionary histories.

Electronic Resource

0039-6338

Political Science

NATO Expansion

0035-1466

Linguistics and Literary Studies

Notes et Documents

0885-6125

Reinforcement learning ; deictic representations ; sensory-motor integration ; hidden state ; non-Markov decision problems

Springer Online Journal Archives 1860-2000

Computer Science

Abstract This article considers adaptive control architectures that integrate active sensory-motor systems with decision systems based on reinforcement learning. One unavoidable consequence of active perception is that the agent's internal representation often confounds external world states. We call this phoenomenon Perceptual aliasing and show that it destabilizes existing reinforcement learning algorithms with respect to the optimal decision policy. We then describe a new decision system that overcomes these difficulties for a restricted class of decision problems. The system incorporates a perceptual subcycle within the overall decision cycle and uses a modified learning algorithm to suppress the effects of perceptual aliasing. The result is a control architecture that learns not only how to solve a task but also where to focus its visual attention in order to collect necessary sensory information.

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] The functional abilities and parallel architecture of the human visual system are a rich source of ideas about visual processing. Any visual task that we can perform quickly and effortlessly is likely to have a computational solution using a parallel algorithm. Recently, several such parallel ...

Electronic Resource

0885-6125

Reinforcement learning ; deictic representations ; sensory-motor integration ; hidden state ; non-Markov decision problems

Springer Online Journal Archives 1860-2000

Computer Science

Abstract This article considers adaptive control architectures that integrate active sensory-motor systems with decision systems based on reinforcement learning. One unavoidable consequence of active perception is that the agent's internal representation often confounds external world states. We call this phoenomenon perceptual aliasingand show that it destabilizes existing reinforcement learning algorithms with respect to the optimal decision policy. We then describe a new decision system that overcomes these difficulties for a restricted class of decision problems. The system incorporates a perceptual subcycle within the overall decision cycle and uses a modified learning algorithm to suppress the effects of perceptual aliasing. The result is a control architecture that learns not only how to solve a task but also where to focus its visual attention in order to collect necessary sensory information.

Electronic Resource

1432-1106

Head movements ; Visuomotor coordination ; Saccadic eye movement ; Latencies ; Human

Springer Online Journal Archives 1860-2000

Medicine

Abstract We compared the head movements accompanying gaze shifts while our subjects executed different manual operations, requiring gaze shifts of about 30°. The different tasks yielded different latencies between gaze shifts and hand movements, and different maximum velocities of the hand. These changes in eye-hand coordination had a clear effect on eye-head coordination: the latencies and maximum velocities of head and hand were correlated. The same correlation between movements of the head and hand was also found within a task. Therefore, the changes in eye-head coordination are not caused by changes in the strategy of the subjects. We conclude that head movements and saccades during gaze shifts are not based on the same command: head movements depend both on the actual saccade and on possible future gaze shifts.

Electronic Resource

1432-0770

Springer Online Journal Archives 1860-2000

Biology

Computer Science

Physics

Abstract A central task of perception can be defined as one of computing hierarchies of invariants. One way of representing such invariants in intermediate levels of abstraction in this hierarchy is to use discrete units. These have been termed value units. A problem with such an encoding is that there has not been a good way to represent accurate numerical quantities using these units. This paper remedies the deficiency by describing a scheme that interpolates values between units representing fixed numerical quantities. The scheme has nice properties: it extends across functional mappings and it allows different sources of evidence to be combined.

Electronic Resource

1617-4623

Springer Online Journal Archives 1860-2000

Biology

Summary Assay conditions are described which permit detection of cryptic temperature sensitive RNA polymerases in vitro. RNA polymerase was prepared from fifteen different temperature sensitive mutants of Salmonella typhimurium chosen at random from a larger group isolated by localized mutagenesis and uridine suicide techniques. The dependence of enzyme activity on temperature, ionic strength and pH was studied in vitro. Assays at higher ionic strength (0.23 M) and temperature (50°C) distinguish three classes of mutants (Table 2). Activity of seven mutant RNA polymerases (called Class 1) under these conditions was 1% to 5% that of the parental RNA polymerase. Five mutant RNA polymerases (called Class 2) had 18% to 64% of the parental activity and three were not distinguishable from the parental enzyme under these conditions. Mixing experiments showed that the defect in Class 1 mutant enzymes is a property of the enzymes and not due to a diffusible inhibitor. In one case the lesion was shown to reside in the core enzyme. Class 1 mutant RNA polymerases were shown to be irreversibly inactivated during the assay at higher temperature and ionic strength. This suggests that the Class 1 enzymes may be more thermolabile than the wild type enzyme or may fail to be protected from thermal denaturation by formation of a ternary complex with template and product. We conclude that the method used to isolate these mutants (Young et al., 1976) and the assay described here (Table 2) are efficient ways to isolate and detect temperature sensitive RNA polymerase mutants of Salmonella typhimurium.

Electronic Resource

1573-1405

Springer Online Journal Archives 1860-2000

Computer Science

Abstract Computer vision is embracing a new research focus in which the aim is to develop visual skills for robots that allow them to interact with a dynamic, realistic environment. To achieve this aim, new kinds of vision algorithms need to be developed which run in real time and subserve the robot's goals. Two fundamental goals are determining the location of a known object. Color can be successfully used for both tasks. This article demonstrates that color histograms of multicolored objects provide a robust, efficient cue for indexing into a large database of models. It shows that color histograms are stable object representations in the presence of occlusion and over change in view, and that they can differentiate among a large number of objects. For solving the identification problem, it introduces a technique calledHistogram Intersection, which matches model and image histograms and a fast incremental version of Histogram Intersection, which allows real-time indexing into a large database of stored models. For solving the location problem it introduces an algorithm calledHistogram Backprojection, which performs this task efficiently in crowded scenes.

Electronic Resource