1,517 research outputs found
Using Technology to Enhance Rural Resilience in Pre-hospital Emergencies
The research presented in this paper is supported by RCUK dot.rural Digital Economy Research Hub, University of Aberdeen [grant number EP/G066051/1].Peer reviewedPublisher PD
Yeast RNase H(35) is the counterpart of the mammalian RNase HI, and is evolutionarily related to prokaryotic RNase HII1We dedicate this work to the memory of our colleague Robert Karwan (1959–1997).1
AbstractWe cloned the Saccharomyces cerevisiae homologue of mammalian RNase HI, which itself is related to the prokaryotic RNase HII, an enzyme of unknown function and previously described as having minor activity in Escherichia coli. Expression of the corresponding yeast 35 kDa protein (named by us RNase H(35)) in E. coli and immunological analysis proves a close evolutionary relationship to mammalian RNase HI. Deletion of the gene (called RNH35) from the yeast genome leads to an about 75% decrease of RNase H activity in preparations from the mutated, still viable cells. Sequence comparison discriminates this new yeast RNase H from earlier described yeast enzymes, RNase H(70) and RNase HI
An online learning approach to in-vivo tracking using synergistic features
In this paper we present an online algorithm for robustly tracking surgical tools in dynamic environments that can assist a surgeon during in-vivo robotic surgery procedures. The next generation of in-vivo robotic surgical devices includes integrated imaging and effector platforms that need to be controlled through real-time visual feedback. Our tracking algorithm learns the appearance of the tool online to account for appearance and perspective changes. In addition, the tracker uses multiple features working together to model the object and discover new areas of the tool as it moves quickly, exits and re-enters the scene, or becomes occluded and requires recovery. The algorithm can persist through changes in lighting and pose by using a memory database, which is built online, using a series of features working together to exploit different aspects of the object being tracked. We present results using real in-vivo imaging data from a human partial nephrectomy
Combinatorial functions of two chimeric antibodies directed to human CD4 and one directed to the a-chain of the human interleukin-2 receptor
The general feasibility of chimerization of monoclonal antibodies (mAbs) has already been shown for a large number of
them. In order to evaluate in vitro parameters relevant to immunosuppressive therapy, we have chimerized and synthesized
two anti-CD4 mAbs recognizing two different epitopes on the human T-lymphocyte antigen, CD4. The chimerized mAbs
are produced at levels corresponding to those of the original hybridoma cell lines. With respect to activation of human
complement, the individual Abs are negative; however, when used in combination, complement activation was performed.
When applied in combination, they were found to modulate the CD4 antigen, whereas the individual mAb do not display
this property. Individually they mediate an up to 60% inhibition of the mixed lymphocyte reaction (MLR). However, by
combination of an anti-CD4 mAb with one directed against the a-chain of the human IL2 receptor, nearly 100% inhibition
of the MLR was achieved, even with reduced dosage of the mAbs. Our data suggest that the combination of an anti-CD4
mAb and an anti-IL2Rcc chain mAb is more effective with respect to immunosuppression than each mAb by itself, indicating
that this mAb cocktail could be a new strategy for immunosuppressive therapy
Cortisol and 17-hydroxyprogesterone levels in saliva of healthy neonates - Normative data and relation to body mass index, arterial cord blood pH and time of sampling after birth
The measurement of cortisol and 17-hydroxyprogesterone (17-OHP) in saliva has become a reliable tool for both the scientist and the clinician for studying adrenal cortical function in the adult and the older child. We have now established in parallel normative data for salivary cortisol and 17-OHP levels in healthy neonates. We have asked whether or not there is a circadian rhythm of cortisol and 17-OHP saliva levels in neonates. Furthermore, we have asked whether salivary hormone levels correlated with auxologic and clinical data and time of sampling. Cortisol and 17-OHP levels in saliva samples from 119 healthy neonates (55 girls, 64 boys) were measured using in-house time-resolved fluorescent immunoassays. Saliva samples were obtained using a saliva collecting tube three times a day on the first or second day of life. Gender and gestational age did not influence salivary cortisol and 17-OHP levels. No significant circadian rhythm of salivary hormone levels was detected in this group of newborns. However, body mass index, arterial cord blood pH and time of saliva sampling significantly influenced salivary hormone levels. In conclusion, measurement of cortisol and 17-OHP in saliva is feasible in healthy neonates. The existence of normative data forms the basis for future studies on pathophysiologic states in the newborn period. Copyright (C) 2000 S. Karger AG, Basel
A learning algorithm for visual pose estimation of continuum robots
Continuum robots offer significant advantages for surgical intervention due to their down-scalability, dexterity, and structural flexibility. While structural compliance offers a passive way to guard against trauma, it necessitates robust methods for online estimation of the robot configuration in order to enable precise position and manipulation control. In this paper, we address the pose estimation problem by applying a novel mapping of the robot configuration to a feature descriptor space using stereo vision. We generate a mapping of known features through a supervised learning algorithm that relates the feature descriptor to known ground truth. Features are represented in a reduced sub-space, which we call eigen-features. The descriptor provides some robustness to occlusions, which are inherent to surgical environments, and the methodology that we describe can be applied to multi-segment continuum robots for closed-loop control. Experimental validation on a single-segment continuum robot demonstrates the robustness and efficacy of the algorithm for configuration estimation. Results show that the errors are in the range of 1°
Depth-dependent critical behavior in V2H
Using X-ray diffuse scattering, we investigate the critical behavior of an
order-disorder phase transition in a defective "skin-layer" of V2H. In the
skin-layer, there exist walls of dislocation lines oriented normal to the
surface. The density of dislocation lines within a wall decreases continuously
with depth. We find that, because of this inhomogeneous distribution of
defects, the transition effectively occurs at a depth-dependent local critical
temperature. A depth-dependent scaling law is proposed to describe the
corresponding critical ordering behavior.Comment: 5 pages, 4 figure
Glassy timescale divergence and anomalous coarsening in a kinetically constrained spin chain
We analyse the out of equilibrium behavior of an Ising spin chain with an
asymmetric kinetic constraint after a quench to a low temperature T. In the
limit T\to 0, we provide an exact solution of the resulting coarsening process.
The equilibration time exhibits a `glassy' divergence \teq=\exp(const/T^2)
(popular as an alternative to the Vogel-Fulcher law), while the average domain
length grows with a temperature dependent exponent, \dbar ~ t^{T\ln 2}. We show
that the equilibration time \teq also sets the timescale for the linear
response of the system at low temperatures.Comment: 4 pages, revtex, includes two eps figures. Proof of energy barrier
hierarchy added. Version to be published in Phys Rev Let
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