Cryogenic scanning tunneling spectroscopy studies of inhomogeneous superconductors

We applied scanning tunneling microscopy and spectroscopy, combined with magnetic susceptibility measurements and Mossbauer spectroscopy, in studies of three superconducting materials. Two belong to a new class of high T_c magnetic-superconductor systems, R_1.4Ce_0.6RuSr₂Cu₂O_10-δ (R=Eu and Gd), which are magnetically ordered at T_N≪T_c. The third is a granular normal-superconductor system, where the superconducting phase is YNi₂B₂C. In this paper we focus on the tunneling measurements, which exhibit large spatial variations of the local electronic properties for all three materials. Albeit, these local measurements also reveal pronounced differences between the third and the first two systems, which will be discussed in view of their macroscopic properties.     

Synthesis and characterization of broad-band polarization-mode dispersion equalizers

A synthesis algorithm for the design of a finite impulse response polarization-mode dispersion (PMD) equalizer is described and used for characterization of the filter. Defined in terms of the residual maximum differential group delay, the performance of the equalizer is characterized as a function of the equalizer order and period. The synthesis algorithm uses spectral factorization to analytically find estimated equalizer control variables. The control variables are then used as initial guess for an optimization procedure that minimize the maximum differential group delay in the frequency range of interest.     

3-D curve matching using splines

A machine vision algorithm to find the longest common subcurve of two 3-D curves is presented. The curves are represented by splines fitted through sequences of sample points extracted from dense range data. The approximated 3-D curves are transformed into 1-D numerical strings of rotation and translation invariant shape signatures, based on a multiresolution representation of the curvature and torsion values of the space curves. The shape signature strings are matched using an efficient hashing technique that finds longest matching substrings. The results of the string matching stage are later verified by a robust, least-squares, 3-D curve matching technique, which also recovers the Euclidean transformation between the curves being matched. This algorithm is of average complexity O(n) where n is the number of the sample points on the two curves. The algorithm has applications in assembly and object recognition tasks. Results of assembly experiments are included.     

Improved blood glucose control for critically ill subjects

For patients in intensive care units (ICUs), control of blood glucose level is an important factor in reducing serious complications and mortality. Standard protocols for glucose control in ICUs have been based on infrequent glucose measurements, look-up tables to determine the appropriate insulin infusion rates, and bedside administration of the insulin infusion by ICU staff. In this paper a new automatic control strategy is proposed based on frequent glucose measurements and a self-tuning control technique. During a short initial time period when manual glucose control is performed using a standard protocol, a simple dynamic model of the glucose-insulin system is identified in real time using recursive least squares. Then an adaptive PID controller is tuned, based on the model parameters, and the controller is turned on. A simulation study based on detailed physiological models of the glucose-insulin dynamics demonstrates that the proposed control strategy performs better than standard protocols for insulin infusion.     

Integrating and customizing heterogeneous e-commerce applications

A broad spectrum of electronic commerce applications is currently available on the Web, providing services in almost any area one can think of. As the number and variety of such applications grow, more business opportunities emerge for providing new services based on the integration and customization of existing applications. (Web shopping malls and support for comparative shopping are just a couple of examples.) Unfortunately, the diversity of applications in each specific domain and the disparity of interfaces, application flows, actor roles in the business transaction, and data formats, renders the integration and manipulation of applications a rather difficult task. In this paper we present the Application Manifold system, aimed at simplifying the intricate task of integration and customization of e-commerce applications. The scope of the work in this paper is limited to web-enabled e-commerce applications. We do not support the integration/customization of proprietary/legacy applications. The wrapping of such applications as web services is complementary to our work. Based on the emerging Web data standard, XML, and application modeling standard, UML, the system offers a novel declarative specification language for describing the integration/customization task, supporting a modular approach where new applications can be added and integrated at will with minimal effort. Then, acting as an application generator, the system generates a full integrated/customized e-commerce application, with the declarativity of the specification allowing for the optimization and verification of the generated application. The integration here deals with the full profile of the given e-commerce applications: the various services offered by the applications, the activities and roles of the different actors participating in the application (e.g., customers, vendors), the application flow, as well as with the data involved in the process. This is in contrast to previous works on Web data integration that focused primarily on querying the data available in the applications, mostly ignoring the additional aspects mentioned above. Received: 30 October 2000 / Accepted 14 March 2001 Published online: 2 August 2001     

3-D Nanofibrous electrospun multilayered construct is an alternative ECM mimicking scaffold

Extra cellular matrix (ECM) is a natural cell environment, possesses complicated nano- and macro- architecture. Mimicking this three-dimensional (3-D) web is a challenge in the modern tissue engineering. This study examined the application of a novel 3-D construct, produced by multilayered organization of electrospun nanofiber membranes, for human bone marrow-derived mesenchymal stem cells (hMSCs) support. The hMSCs were seeded on an electrospun scaffold composed of poly ε-caproloactone (PCL) and collagen (COL) (1:1), and cultured in a dynamic flow bioreactor prior to in vivo implantation. Cell viability after seeding was analyzed by AlamarBlue™ Assay. At the various stages of experiment, cell morphology was examined by histology, scanning electron microscopy (SEM) and confocal microscopy. Results: A porous 3-D network of randomly oriented nanofibers appeared to support cell attachment in a way similar to traditionally used tissue culture polysterene plate. The following 6 week culture process of the tested construct in the dynamic flow system led to massive cell proliferation with even distribution inside the scaffold. Subcutaneous implantation of the cultured construct into nude mice demonstrated good integration with the surrounding tissues and neovascularization. Conclusion: The combination of electrospinning technology with multilayer technique resulted in the novel 3-D nanofiber multilayered construct, able to contain efficient cell mass necessary for a successful in vivo grafting. The success of this approach with undifferentiated cells implies the possibility of its application as a platform for development of constructs with cells directed into various tissue types.     

Experimental realization of an imaging system with an extended depth of field

We describe the experimental realization of an all-optical imaging system with an extended depth of field (DOF). The core of the system is a phase mask consisting of 16 Fresnel lenses (FLs) that are spatially multiplexed and mutually exclusive. Because each FL, in tandem with the primary lens, is designed to produce a sharp image for a specific object plane location, jointly the FLs achieve a wide DOF. However, the resultant image exhibits reduced resolution. The acquired image, onto which we did not apply any postprocessing, clearly is sharper than that acquired with a clear-aperture imaging system with the same pupil size.     

Control of hypertension in family practice by the doctor-nurse team

In Israel, most hypertensives are treated by the family doctor alone. In 45 family practices, nurses were given a more active part to play in the follow-up of these patients, including measuring weight and blood pressure, giving dietary guidance, checking patient compliance and actively following up drop-outs. After two years' follow-up, of a total of 4,255 patients studied, 82.4 per cent were under control (diastolic blood pressure less than 95 mmHg) compared to 42.1 per cent at the onset of the study. The drop-out rate was 0.65 per cent.     

Dynamic repair priority for a transfer line with a finite buffer

We formulate a continuous-time Markov chain model of a transfer line in which there are two unreliable machines separated by a finite buffer. Due to limited repair resources, simultaneous repairs are not possible in cases where both machines fail, and therefore we develop a repair priority rule that depends on the number of work-pieces present in the buffer. Each machine is characterized by three exponentially distributed random variables: processing time, time to failure, and time to repair. We provide a stochastic model for finding an optimal repair priority rule and an efficient algorithm accompanied by easy-to-use Matlab software. An extensive numerical study is performed to test the sensitivity of the proposed dynamic repair priority rule. While in previous studies repair priority was given to the bottleneck machine, we show that there are situations in which priority should be given to the non-bottleneck machine. Finally, we identify conditions in which adding a second technician is economically advisable.     

Fiber-optic pulsed photothermal radiometry for fast surface-temperature measurements

Temperature measurement based on pulsed photothermal radiometry is described. In this technique a body is irradiated by a laser pulse and its temperature is inferred from the shape of the emitted photothermal-signal curve. A prototypical system based on a pulsed CO(2) laser, an IR detector, and IR-transmitting silver halide optical fibers was constructed and used to evaluate the feasibility of this technique. An important feature of the technique is that changes in sample emissivity or geometric factors do not introduce errors in the temperature determination. Theory, simulation, and experimental results are given and discussed.