Development of male contraceptive vaccine--a perspective

Anti-disialoganglioside (GD2) monoclonal antibodies (MAbs) have been used in vivo for immunolocalization and in phase I and II trials to target disseminated neuroblastoma, the most common extracranial solid tumor in children. However, the efficacy of these first-generation MAbs is likely to be improved by using engineered anti-GD2 antibodies. The generation of single-chain antibody fragments (scFv) could be very helpful as these molecules can be further modified to produce recombinant molecules with pre-defined properties such as immunotoxins, chimeric, or bispecific antibodies. Thus, a scFv directed against GD2 (scFv 7A4) was cloned, sequenced, and expressed. Its binding properties were characterized and compared to that of the parental MAb 7A4. Nucleotide sequence analysis of the scFv 7A4 indicated that its VH region belongs to the V region IIID subgroup and the V kappa to the V region II subgroup. The scFv 7A4 bound to GD2+ neuroblastoma cell lines but not to GD2- cell lines or to GD2- cells isolated from peripheral blood. ELISA and thin-layer chromatography (TLC) indicated that it retained the anti-GD2 specificity, and exhibited a slight cross-reaction with GD3 as the parental MAb. This scFv makes it possible to develop new useful reagents through genetic engineering for adjuvant tumor therapy.     

An improvement to the interacting multiple model (IMM) algorithm

Computing the optimal conditional mean state estimate for a jump Markov linear system requires exponential complexity, and hence, practical filtering algorithms are necessarily suboptimal. In the target tracking literature, suboptimal multiple-model filtering algorithms, such as the interacting multiple model (IMM) method and generalized pseudo-Bayesian (GPB) schemes, are widely used for state estimation of such systems. We derive a reweighted interacting multiple model algorithm. Although the IMM algorithm is an approximation of the conditional mean state estimator, our algorithm is a recursive implementation of a maximum a posteriori (MAP) state sequence estimator. This MAP estimator is an instance of a previous version of the EM algorithm known as the alternating expectation conditional maximization (AECM) algorithm. Computer simulations indicate that the proposed reweighted IMM algorithm is a competitive alternative to the popular IMM algorithm and GPB methods     

Friction stir channeling: Characterization of the channels

Commercially available compact heat exchangers are currently fabricated in several steps by joining multiple tubes, or by independently fabricating and joining fluid channels. Friction stir channeling (FSC) is a simple and innovative technique of manufacturing heat exchangers in a single step by creating continuous, integral channels in a monolithic plate in a single pass. FSC relies on the frictional heat generated between the tool material and the metal workpiece to soften and deform the material to facilitate the creation of a continuous channel. The channel shape, size, and integrity depend on the processing parameters and the tool design. In this paper the structural characteristics and the relationship between the channel features and the processing parameters are discussed. FSC is being developed as a technique for manufacturing heat exchangers. The channel is characterized by roughness features on the inside, which can be analyzed using optical microscopy techniques.     

Free vibration studies on typical large flexible spacecraft appendages under vacuum conditions

This paper deals with theoretical and experimental investigations on the free vibration characteristics of representative large flexible solar array appendages used in spacecrafts under vacuum environmental conditions prevailing in space. Eight different configurations of solar panels with varied flexibility and surface area have been studied. The theoretical results, namely the modal parameters, have been correlated with results from experiments. These are performed on solar arrays of different configurations under varied parameters of panel flexibility, vacuum and amplitudes of vibration.     

Development of Joints Between Two Parallel SS-Laminated BSCCO/Ag HTS Tapes

Stainless-steel (SS)-laminated high-strength high-temperature superconductor (HTS) BSCCO tapes are now commercially available for different practical applications. These SS-laminated HTS tapes are tolerant to smaller winding diameters, and the pancake winding becomes much easier due to higher tensile strength. However, the joining of two parallel SS-laminated HTS tapes is more complicated because of their limitation in maximum temperature exposure. The joining between the pancakes however becomes resistive due to the SS-laminated layer. We have experimentally studied the performance of the bridge joint between two parallel SS-laminated BSCCO tapes with different numbers of cross bridges of two different types of BSCCO tape. The splices of both SS-laminated BSCCO tape and silver (Ag)-sheathed BSCCO tape have been used as cross bridges at the joint. The current–voltage $I$–$V$ characteristic curves of the joints were investigated at 77 K, which is liquid nitrogen temperature. Joint resistance has been estimated from the $I$– $V$ characteristic curve. The lowest joint resistance achieved at 77 K at self-field, with six bridges made of SS-laminated HTS tape, is 0.78 $mu Omega$, and the lowest joint resistance of six Ag-sheathed HTS bridges is 0.54 $muOmega$. The corresponding contact resistances are 0.402 and 0.27 $muOmegacdothbox{cm}^{2}$ for both types of joints.      

Systematic design of wideband ΔΣ modulators for WiFi/WiMAX receivers

Modern multi-standard receivers in deep-submicron technologies pose significant design challenges on the analog baseband. Moving this analog filtering to the digital domain simplifies the design, yielding a process-scalable implementation. However, analog-to-digital converter (ADC) specifications now become more stringent and must be obtained by comprehending the standard and the system. Assuming a receiver NF of 5.96 dB and SNR degradation of 0.36 dB by the ADC, the proposed dual-mode WiFi/WiMAX receiver attains an input sensitivity of −74 dBm (20 MHz channel bandwidth). To accommodate the high dynamic range and the anti-alias rejection needed for the system, a Delta-Sigma (ΔΣ) ADC is proposed. Single-loop and Multi-Stage Noise-Shaping (MASH) architectures that achieve a SNR of 69 dB at a low oversampling ratio (OSR) of 8 for a conversion bandwidth of 40 MHz (108 Mbps, OFDM) are investigated at system level. Based on thermal noise, harmonic distortion, and power tradeoffs, a ΔΣ ADC design that meets the design specifications is presented.     

Hybrid inversion of elastic moduli of composite plates from ultrasonic transmission spectra using PVDF plane wave sensor

Determination of the elastic moduli of polymer matrix based structural composite materials is necessary to characterize their strength after fabrication and while in service. This paper reports a modification to goniometry based ultrasonic through transmission data collection by using wide aperture low cost polyvinylidene fluoride (PVDF) based receiver. The use of PVDF based receiver more than satisfies the plane-wave conditions required from measurement. The use of a hybrid inversion technique which combines genetic algorithm based evolutionary approach, critical angle information and the use of stiffness invariants is implemented for determination of stiffness values from experimental transmission spectra measurements. Results for unidirectional and a multi-layered composite laminate are presented.