Levels and sublevels of composition algebras over \mathfrak{p}-adic function fields

In [7], the level and sublevel of composition algebras are studied, wherein these quantities are determined for those algebras defined over local fields. In this paper, the level and sublevel of composition algebras, of dimension 4 and 8 over rational function fields over local non-dyadic fields, are determined completely in terms of the local ramification data of the algebras. The proofs are based on the “classification” of quadratic forms over such fields, as is given in [8]. The first author gratefully acknowledges financial support provided through the European Community’s Human Potential Programme, under contract HPRN-CT-2002-00287 KTAGS, which made possible an enjoyable stay at Ghent University.     

A sol-gel derived pH-responsive bovine serum albumin molecularly imprinted poly(ionic liquids) on the surface of multiwall carbon nanotubes

A pH-responsive surface molecularly imprinted poly(ionic liquids) (MIPILs) was prepared on the surface of multiwall carbon nanotubes (MWCNTs) by a sol-gel technique. The material was synthesized using a 3-aminopropyl triethoxysilane modified multiwall carbon nanotube (MWCNT-APTES) as the substrate, bovine serum albumin (BSA) as the template molecule, an alkoxy-functionalized IL 1-(3-trimethoxysilyl propyl)-3-methyl imidazolium chloride ([TMSPMIM]Cl) as both the functional monomer and the sol-gel catalyst, and tetraethoxysilane (TEOS) as the crosslinking agent. The molecular interaction between BSA and [TMSPMIM]Cl was quantitatively evaluated by UV–vis spectroscopy prior to polymerization so as to identify an optimal template/monomer ratio and the most suitable pH value for the preparation of the MWCNTs@BSA-MIPILs. This strategy was found to be effective to overcome the problems of trial-and-error protocol in molecular imprinting. The optimum synthesis conditions were as follows: template/monomer ratio 7:20, crosslinking agent content 2.0–2.5 mL, temperature 4 °C and pH 8.9 Tris–HCl buffer. The influence of incubation pH on adsorption was also studied. The result showed that the imprinting effect and selectivity improved significantly with increasing incubation pH from 7.7 to 9.9. This is mainly because the non-specific binding from electrostatic and hydrogen bonding interactions decreased greatly with the increase of pH value, which made the specific binding affinity from shape selectivity strengthened instead. The polymers synthesized under the optimal conditions were then characterized by BET surface area measurement, FTIR, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The adsorption capacity, imprinting effect, selective recognition and reusability were also evaluated. The as-prepared MWCNTs@BSA-MIPILs were also found to have a number of advantages including high surface area (134.2 m² g⁻¹), high adsorption capacity (55.52 mg g⁻¹), excellent imprinting effect (imprinting factor of up to 5.84), strong selectivity (selectivity factor of 2.61 and 5.63 for human serum albumin and bovine hemoglobin, respectively), and good reusability.     

Alternatives for testing total dual integrality

In this paper we provide characterizing properties of totally dual integral (TDI) systems, among others the following: a system of linear inequalities is TDI if and only if its coefficient vectors form a Hilbert basis, and there exists a test-set for the system’s dual integer programs where all test vectors have positive entries equal to 1. Reformulations of this provide relations between computational algebra and integer programming and they contain Applegate, Cook and McCormick’s sufficient condition for the TDI property and Sturmfels’ theorem relating toric initial ideals generated by square-free monomials to unimodular triangulations. We also study the theoretical and practical efficiency and limits of the characterizations of the TDI property presented here. In the particular case of set packing polyhedra our results correspond to endowing the weak perfect graph theorem with an additional, computationally interesting, geometric feature: the normal fan of the stable set polytope of a perfect graph can be refined into a regular triangulation consisting only of unimodular cones.     

Adaptive nonuniform phase-shift-key modulation for multimediatraffic in wireless networks

The characteristics of mobile wireless communication channels fluctuate for many reasons, including movement of the radios, changes in path attenuation, and variations in interference. Several adaptive signaling techniques have been proposed for use in wideband code-division multiple-access (CDMA) systems including adaptive data rates, adaptive spreading code rates, discontinuous transmission, and multicode CDMA. We introduce adaptive signaling techniques that use nonuniform phase-shift-key (PSK) modulation. These techniques have several advantages for use in CDMA communications, and they support multimedia transmission by simultaneously delivering different types of traffic, each with its own required quality of service. The signaling methods that we propose deliver a basic message at a specified error rate and simultaneously deliver an additional message by exploiting any extra capability that is available. We show that by adapting the location of the points in a PSK constellation, the throughput can be maximized for the additional message while maintaining an acceptable error rate for the basic message. Responses to larger changes in channel quality are accomplished by adapting the PSK constellation size, signaling rate, and error-correcting code. Examples of adaptive signaling schemes that employ nonuniform PSK constellations are presented, including an application to a cellular CDMA system     

Concatenated parity and turbo codes

Turbo codes have an error floor that is caused by low-weight error events. Here, it is shown that a concatenated code with a simple rectangular parity-check outer code and a turbo inner code can significantly reduce the error floor. It is also shown that in several situations, the concatenated parity-check and turbo code performs significantly better than a turbo code alone     

On Multiple Points of Meromorphic Functions

Lower bounds are established for the number of zeros of thelogarithmic derivative of a meromorphic function of small growthwith few poles.     

Pilot-Assisted and Blind Joint Data Detection and Channel Estimation in Partial-Time Jamming

We consider a communication scenario in which a message is received in the presence of partial-time Gaussian jamming and additive white Gaussian noise. We consider a quasi-static channel, in which the amplitude and phase are constant over each packet transmission. The receiver does not know the amplitude and phase of the incoming signal, which symbols are jammed, or even the statistics of the jammer, such as the jamming power and jamming probability. In this scenario, the receiver must accurately estimate the parameters of the channel and the jamming to achieve good performance. We apply the expectation-maximization (EM) algorithm to iteratively approximate the maximum-likelihood (ML) estimator for all of the parameters. We find that the overall performance of the EM algorithm is very sensitive to the initial estimates, so we propose a new initial estimator that offers good performance. The EM algorithm approach requires pilot symbols to resolve a phase ambiguity. Thus, we also present a blind estimation algorithm to avoid the reduction in overall code rate from the use of pilot symbols     

Wearable Soft Technologies for Haptic Sensing and Feedback

Virtual reality (VR) and augmented reality (AR) systems have garnered recent widespread attention due to increased accessibility, functionality, and affordability. These systems sense user inputs and typically provide haptic, audio, and visual feedback to blend interactive virtual environments with the real world for an enhanced or simulated reality experience. With applications ranging from immersive entertainment, to teleoperation, to physical therapy, further development of this technology has the potential for impact across multiple disciplines. However, VR/AR devices still face critical challenges that hinder integration into everyday life and additional applications; namely, the rigid and cumbersome form factor of current technology that is incompatible with the dynamic movements and pliable limbs of the human body. Recent advancements in the field of soft materials are uniquely suited to provide solutions to this challenge. Devices fabricated from flexible and elastic bio-compatible materials have significantly greater compatibility with the human body and could lead to a more natural VR/AR experience. This review reports state-of-the-art experimental studies in soft materials for wearable sensing and haptic feedback in VR/AR applications, explores emerging soft technologies for on-body devices, and identifies current challenges and future opportunities toward seamless integration of the virtual and physical world.