Embracing dynamic evolution in distributed systems

Distributed systems aren't only more widespread than they used to be, but they've become more critical than ever, having moved from client-server systems to multitier heterogeneous systems. Many of these applications - such as telephone exchange systems - must be operational 24 hours a day, so shutting them down isn't a viable option for administrators who must make systemwide changes. As a system becomes larger and more complex, the likelihood of defects increases, which means a greater number of required fixes. Studies have found that nearly half the software development effort in complex distributed systems is devoted to maintenance. Furthermore, the industry currently favors iterative and incremental development approaches over the traditional waterfall approach in software engineering to flexibly handle requirements and reduce project risks by deploying smaller changes. These changes are regular and predictable. So, how can we build distributed systems to handle these kinds of changes? The answer, we argue, is dynamic evolution. From a business perspective, dynamic evolution permits frequent upgrades, which reduces the time between releases. Dynamic evolution also enhances flexibility in implementing changes to unforeseen and fluctuating business requirements. Many specialized distributed systems will benefit from factoring dynamic evolution into their designs. We can easily achieve dynamic evolution in a component-based distributed system. The abstraction of components and their connectors facilitates system structures to accommodate changes.     

Dielectrophoretic batch fabrication of bundled carbon nanotube thermal sensors

We present a feasible technology for batch assembly of carbon nanotube (CNT) devices by utilizing ac electrophoretic technique to manipulate multiwalled bundles on an Si/SiO/sub 2/ substrate. Based on this technique, CNTs were successfully and repeatably manipulated between microfabricated electrodes. By using this parallel assembly process, we have investigated the possibility of batch fabricating functional CNT devices when an ac electrical field is applied to an array of microelectrodes that are electrically connected together. Preliminary experimental results showed that over 70% of CNT functional devices can be assembled successfully using our technique, which is considered to be a good yield for nanodevices manufacturing. Besides, the devices were demonstrated to potentially serve as novel thermal sensors with low power consumption (/spl sim/microwatts) with electronic circuit response of approximately 100 kHz in constant current mode operation. In this paper, we will present the fabrication process of this feasible batch manufacturable method for functional CNT-based thermal sensors, which will dramatically reduce production costs and production time of nanosensing devices and potentially enable fully automated assembly of CNT-based devices. Experimental results from the thermal sensors fabricated by this batch process will also be discussed.     

Multicategory Proximal Support Vector Machine Classifiers

Given a dataset, each element of which labeled by one of k labels, we construct by a very fast algorithm, a k-category proximal support vector machine (PSVM) classifier. Proximal support vector machines and related approaches (Fung & Mangasarian, 2001; Suykens & Vandewalle, 1999) can be interpreted as ridge regression applied to classification problems (Evgeniou, Pontil, & Poggio, 2000). Extensive computational results have shown the effectiveness of PSVM for two-class classification problems where the separating plane is constructed in time that can be as little as two orders of magnitude shorter than that of conventional support vector machines. When PSVM is applied to problems with more than two classes, the well known one-from-the-rest approach is a natural choice in order to take advantage of its fast performance. However, there is a drawback associated with this one-from-the-rest approach. The resulting two-class problems are often very unbalanced, leading in some cases to poor performance. We propose balancing the k classes and a novel Newton refinement modification to PSVM in order to deal with this problem. Computational results indicate that these two modifications preserve the speed of PSVM while often leading to significant test set improvement over a plain PSVM one-from-the-rest application. The modified approach is considerably faster than other one-from-the-rest methods that use conventional SVM formulations, while still giving comparable test set correctness.Editor Shai Ben-David     

High copper loading metal organic decomposition paste for printed electronics

A screen-printable metal organic decomposition (MOD) paste with a high copper loading has been developed. Copper precursor (copper hydroxide and copper formate) and copper flasks are used as copper sources in the paste. The copper precursor is reduced to copper nanoparticles during sintering at a temperature of 200 °C for 3 min and forms a conductive film, whereas the copper flakes are added to increase the conductivity of the printed film. The optimal formulation of the screen-printing MOD paste was obtained with a copper hydroxide to formic acid ratio of 0.875 and by adding copper flakes to reach a total copper loading of 30 wt%. The printed film after sintering had a sheet resistance of 39 mΩ/sq and a volume resistivity of 21 μΩ cm.     

A novel multiple layers name disambiguation framework for digital libraries using dynamic clustering

In many types of databases, such as a science bibliography database, the name attribute is the most commonly used identifier to recognize entities. However, names are frequently ambiguous and not always unique, thereby causing problems in various fields. Name disambiguation is a data management task that aims to properly distinguish different entities that share the same name, particularly for large databases such as digital libraries, because the information that can be used to identify author’s name is limited. In digital libraries, the issue of ambiguous author names occurs due to the existence of multiple authors with the same name or different name variations for the same author. Most previous works conducted to solve this issue frequently used hierarchical clustering approaches based on information within citation records, e.g., co-authors and publication titles. In the present study, we propose a multiple layers name disambiguation framework that is not only applicable to digital libraries but can also be easily extended to other applications. Our framework adopts a dynamic clustering mechanism to minimize clustering errors. We evaluated our approach on real world corpora, and favorable experiment results indicated that our proposed framework was feasible.     

A videofluoroscopic comparison of straw and cup drinking: the potential influence on dental erosion

Tracheostoma valves are often required in the rehabilitation process of speech after total laryngectomy. Patients are thus able to speak without using their hands to close the tracheostoma. The improved Groningen tracheostoma valve consists of a "cough" valve with an integrated ("speech") valve, which closes for phonation. The cough valve opens as the result of pressure produced by the lungs during a cough. The speech valve closes by the airflow produced by the lungs, thus directing air from the lungs into the esophagus at a deliberately chosen moment. An experimental setup with a computer-based acquisition program was developed to measure the pressure at which the cough valve opened and the flow at which the speech valve closed. In addition, the airflow resistance coefficient of the tracheostoma valve was defined and measured with an open speech valve. Both dry air from a cylinder and humid expired air were used. Results showed a pressure range of 1-7 kPa to open the cough valve and a flow range of 1.2-2.7 l/s to close the speech valve. These values were readily attained during speech, while the flow range occurred above values reached in quiet breathing. The device appeared to function well in physiological ranges and was optimally adjustable to an individual setting. No significant differences were measured between air from a cylinder and humid expired air. Findings showed that methods used to obtain results could be employed as a reference method for comparing aerodynamic characteristics of tracheostoma valves.     

Direct analysis of single rat peritoneal mast cells with laser vaporization/ionization mass spectrometry

A linear time-of-flight mass spectrometer was used as a detector for flow cytometry. These two techniques were coupled by a laser vaporization/ionization interface. The estimated mass detection limit of the combined system was 20 amol of serotonin standard with one laser pulse. An aqueous buffer at physiological pH was used to ensure compatibility with cells. Rat peritoneal mast cells (RPMCs) were dispensed into the mass spectrometer in a single file confined within a 20-micron-i.d. capillary. By using the mass spectrometer as a detector, no precolumn staining or derivatization is required. Determination of serotonin and histamine in individual cells was demonstrated. With this method, hundreds of cells can be analyzed within a few minutes. The average amounts of histamine and serotonin per RPMC were found to be 0.75 +/- 0.33 and 0.11 +/- 0.06 fmol, respectively. No correlation was found between the amounts of the two amines in each cell.     

3D Printing of Arbitrary Perovskite Nanowire Heterostructures

Deterministic integration of arbitrary semiconductor heterostructures opens a new class of modern electronics and optoelectronics. However, the realization of such heterostructures continues to suffer from impracticality, requiring energy- and labor-intensive, time-consuming fabrication processes. Here a 3D printing approach to fabricate freestanding metal halide perovskite nanowire heterostructures with a high degree of control over shape and composition is demonstrated. These features arise from freeform guiding of evaporation-driven perovskite crystallization by a femtoliter precursor meniscus formed on a printing nozzle. By using a double-barreled nanopipette as a printing nozzle, “all-at-once” heterostructure fabrication is achieved within seconds. The 3D-printed perovskite nanowire heterojunctions with multiple emission colors provide exciting optical functionalities such as programmable color mixing and encryption at the single nanopixel level. This “lithography-free” additive approach opens up the possibility to freely design and realize heterostructure-based devices without the constraints of traditional manufacturing processes.     

Performance of unequalized frequency-hopped TDMA with convolutional coding on dispersive fading channels

Increasing demand for wireless personal communications has stimulated research on new digital radio technologies that are optimized for various service applications and environments. This paper discusses the performance of a slow-frequency-hopped time-division multiple-access (SFH-TDMA) technique, which has been proposed as a high-tier extension of a low-complexity TDMA architecture optimized for low-power pedestrian applications. The SFH-TDMA technique considered uses QPSK modulation and rate-1/2 convolutional coding. Numerical results for a wide range of fading rates are obtained through analytical calculation of the effective signal-to-noise ratio combined with a simulation approach which incorporates measured multipath channels and actual frequency correlation among contiguous hopping channels. The results indicate that the SFH-TDMA technique can tolerate root-mean-square (rms) delay spread up to several bit periods without a need for adaptive equalization, but also point to the need for fast power control when the fading is slow and the rms delay spread is much smaller than the bit period. This work is targeted toward understanding the implications to local exchange networks of wireless technology alternatives that could provide access to those networks.     

Atomic‐Level Passivation of Individual Upconversion Nanocrystal for Single Particle Microscopic Imaging

Lanthanide‐doped upconversion nanoparticles (UCNPs) have significant applications for single‐molecule probes and high‐resolution display. However, one of their major hurdles is the weak luminescence, and this remains a grand challenge to achieve at the single‐particle level. Here, 484‐fold luminescence enhancement in LuF₃:Yb³⁺, Er³⁺ rhombic flake UCNPs is achieved, thanks to the Yb³⁺‐mediated local photothermal effect, and their original morphology, size, and good dispersibility are well preserved. These data show that the surface atomic structure of UCNPs as well as transfer from amorphous to ordered crystal structure is modulated by making use of the local photothermal conversion that is generated by the directional absorption of 980 nm light by Yb³⁺ ions. The confocal luminescence images obtained by super‐resolution stimulated emission depletion also show the great enhancement of individual LuF₃:Yb³⁺, Er³⁺ nanoparticles; the high signal‐to‐noise ratio images indicate that the laser treatment technology opens the door for single particle imaging and practical application.