Engineering camel single-domain antibodies and immobilization chemistry for human prostate-specific antigen sensing

The specificity and affinity characteristics of antibodies make them excellent probes in biosensor applications. Unfortunately, their large size, unstable behavior, and random immobilization properties create numerous problems. The single-domain antigen-binding fragment derived from heavy-chain antibodies of camelids (termed VHH) offers special advantages in terms of size, stability, and ease of generating different antibody constructs. In this study, we show the potential of those VHHs in sensing human prostate-specific antigen (hPSA) by SPR technology. Different VHH constructs were immobilized onto commercial and custom-built sensor surfaces by metal chelation, biotin-streptavidin interaction, or covalent coupling. The detection of subnanogram per milliliter hPSA concentrations could be attained on a covalently coupled three-dimensional dextran surface. Moreover, the ratio of different hPSA isoform concentrations could be assessed via a sandwich assay and resulted in the detection of clinically significant antigen concentrations within 15 min. In addition, for the first time, the intrinsic protein stability is presented as an important probe design factor, since our results reveal that higher intrinsic stability offers higher resistance to harsh regeneration conditions. In conclusion, we present VHHs as a novel class of biosensor probes rivaling conventional antibodies and their derived antibody fragments.     

Multi-VDD Testing for Analog Circuits

We present industrial results of a quiescent current testing technique suitable for RF testing. The operational method consists of ramping the power supply and of observing the corresponding quiescent current signatures. When the power supply is swept, all transistors are forced into various regions of operation. This has as advantage that the detection of faults is done for multiple supply voltages and corresponding quiescent currents, enhancing in this form the detectability of faults. We found that this method of structural testing yields fault coverage results comparable to functional RF tests making it a potential and attractive technique for production wafer testing due to its low cost, low testing times and low frequency requirements.José Pineda de Gyvez received the Ph.D. degree from the Eindhoven University of Technology. He is currently a principal scientist at Philips Research Laboratories, The Netherlands. Dr. Pineda was Associate Editor in IEEE Transactions on Circuits and Systems Part I and also Associate Editor for Technology in IEEE Transactions on Semiconductor Manufacturing. His research interests are in the general areas of design for manufacturability and analog signal processing.Guido Gronthoud received the electrical engineering degree from the Delft University in 1975. From 1976 to 1980 he worked at the Delft University on the design of Microwave systems. From 1980 he works with Philips. He has been working in the fields of circuit simulation and modelling for IC designs, CAD development for PCB design and electronic circuits and systems reliability. Since 1998 he is working on test innovation of digital and mixed-signal circuits. His interests are Defect Oriented Test, fault modeling and Process Related Test. He has authored and co-authored technical papers.     

Soil-catalyzed polymerization of phenolics in polluted waters

Some biotic and abiotic soil components are able to catalyze phenol oxidation, producing water-insoluble polymers. In phenol-polluted water bodies, this phenomenon could be exploited to prevent phenol dispersion. The reaction kinetics of phenol polymerization catalyzed by soil samples drawn from unsaturated and aquifer layers was measured in slurry, aerated batch reactors. Catechol was used as a model phenol. The observed catalytic activity is essentially abiotic and can be attributed to inorganic soil components. The rate of phenol removal is first-order with respect to both catechol and soil concentration. Soil activity towards other phenolic compounds was tested, as well. Diphenols show the highest reactivity. Comparisons were performed with the enzymatic activity of phenol oxidases-containing mushroom tissues whose use has been envisaged in the treatment of phenol-polluted waters. The use of phenol oxidases can complement the intrinsic activity of soil for the removal of recalcitrant phenols.     

Proximity, Polarization, and Local Labor Market Performances

Recently, a new methodological approach to empirics of economic dynamics based on nonparametric analysis has been proposed. The approach contemplates the presence of mechanisms of polarization and spatial linkage affecting the spatial characteristics of growth that are ruled out by the basic neoclassical approach while being the starting point of core-periphery models. A nonparametric investigation on the geographical distribution of local labor markets performances in Italy is presented, summarized by the employment rate. The analysis provides empirical support to the prediction that the behavior of the entire cross-section distribution of Italian employment rate can be mainly explained by proximity, and therefore by spatial spillover. The analysis is carried out on a very disaggregated territorial level: the area units considered are the 784 Local Labour Systems (LLSs), defined as travel-to-works areas by the National Statistical Institute (Istat). The basic idea is that distribution dynamics changes whenever conditioned with respect to spatial closeness of LLSs. I investigated the distribution dynamics of employment rate in LLSs over the 1971 to 1996 period by using transition matrices and the stochastic kernel approach. The results show that the employment rate distribution across LLSs has a strong polarization, but it vanishes if it is conditioned to the closer neighbors' employment rate. The analysis suggests that the local labor market performances inside Italy do not present strong territorial discontinuities. This is related to the geographical position of the country with respect to the relevant markets, and it is consistent with the predictions of the core-periphery model.     

A versatile microwave plethysmograph for the monitoring of physiological parameters

A simple microwave technique for in vivo monitoring of human pulmonary and cardiac activity is here presented. The technique is based on detecting the changes in the modulation envelope of amplitude modulated waves passing through the human body. A simplified human chest model was developed, proving an unambiguous correlation between heart blood filling and microwave transmission through the chest. A prototype system for transmittance measurement was realized at the 868.5-MHz operating frequency, demonstrating the feasibility of a small, lowcost microwave plethysmograph. In vivo measurements showed a good agreement with numerical simulations.     

Complexity Reduction of Iterative Receivers Using Low-Rank Equalization

This paper covers the consideration of an iterative or turbo receiver where the nonlinear trellis-based detection of the interleaved and coded data bits is replaced by linear detection using the Wiener filter (WF), i.e., the optimal linear filter based on the mean-square error (MSE) criterion. The equalization of channels with multiple antennas at the receiver as well as frequency-selective transfer functions requires high-dimensional observation vectors which involve computationally intense detectors. We extend an optimal but computationally efficient algorithm, originally derived for single receive antenna systems, to single-input multiple-output (SIMO) channels. To further reduce computational complexity, we apply the suboptimal low-rank multistage WF (MSWF), i.e., the WF approximation in the low-dimensional Krylov subspace, and replace additionally second-order statistics of nonstationary random processes by their time-invariant averages. Complexity investigations reveal the enormous capability of the proposed algorithms to decrease computational effort. Moreover, the analysis based on extrinsic information transfer (EXIT) charts as well as Monte Carlo simulations show that compared with reduced-rank detection methods based on eigensubspaces, the reduced-rank MSWF behaves near optimum although the rank is drastically reduced to two or even one     

Improving routing performance in wireless ad hoc networks using cross-layer interactions

This article presents a combined layer two and three control loop, which allows prediction of link breakage in wireless ad hoc networks. The method monitors the physical layer transmission mode on layer two and exploits the gained knowledge at layer three. The mechanism bases on link adaptation, which is used in IEEE 802.11a WLAN to select the transmission mode according to the link quality. The process of link adaptation contains information that is useful to predict link stability and link lifetime. After introducing the IEEE 802.11a Medium Access Control (MAC) and PHY layer, we present insight to the IEEE 802.11a link adaptation behaviour in multi-hop ad hoc networks. The link adaptation algorithm presented here is derived from Auto Rate Fallback (ARF) algorithm. We survey the performance gain of two newly developed route adaptation approaches exploding the prediction results. One approach is Early Route ReArrangement (ERRA) that starts a route reconstruction procedure before link breakage. Hence, an alternative route is available before connectivity is lost. Early Route Update (ERU) is a complementing approach that enhances this process, by communications among routing nodes surrounding the breaking link. The delay caused by route reconstruction can be significantly reduced if prediction and either of our new route discovery processes is used.