Body Area Networks: A Survey

Advances in wireless communication technologies, such as wearable and implantable biosensors, along with recent developments in the embedded computing area are enabling the design, development, and implementation of body area networks. This class of networks is paving the way for the deployment of innovative healthcare monitoring applications. In the past few years, much of the research in the area of body area networks has focused on issues related to wireless sensor designs, sensor miniaturization, low-power sensor circuitry, signal processing, and communications protocols. In this paper, we present an overview of body area networks, and a discussion of BAN communications types and their related issues. We provide a detailed investigation of sensor devices, physical layer, data link layer, and radio technology aspects of BAN research. We also present a taxonomy of BAN projects that have been introduced/proposed to date. Finally, we highlight some of the design challenges and open issues that still need to be addressed to make BANs truly ubiquitous for a wide range of applications.     

Stochastic event capturing with a single mobile robot in rectangular perimeters

In this paper, we are interested in a single robot detecting intrusions across a rectangular perimeter. We build a stochastic model to analyze the detection quality achieved by a single robot moving along the rectangular perimeter, based on the velocity and the mobility pattern. We define the following intrusion event mode: intrusions occur at a random point along the rectangular perimeter, and stay at that point for a random length of time. In our model, a robot is set to periodically move along a certain route at a variable speed. We derive the general expression for intrusion loss probability. Under the reasonable assumption that, once an intrusion takes place at a random point in the rectangular perimeter, it stays there for a random length of time, which follows an exponential distribution, we then derive the solution to the above problem.     

Psuedosymmetry and pseudomerodry or nonmerohedral twinning for the known structure of diaquabis(quinolin‐8‐olato‐κ2N,O)zinc(II)

The structure of the title centrosymmetric compound, [Zn(C₉H₆NO)₂(H₂O)₂], has already been solved three times [Merritt, Cady & Mundy (1954). Acta Cryst. 7 , 473–476; Palenik (1964). Acta Cryst. 17 , 696–700; Chen, Zhang, Shi, Huang, Liang & Zhou (2003). Acta Cryst. E 59 , m814–m815]. The authors of the two most recent papers state that they attained lower R1 values than that obtained in the 1954 paper, but they do not mention that Merritt et al. had derived the structural model from a twinned crystal. Also, from a structural point of view, there are strong indications that the most recent report is in fact the isostructural Cu^II complex already reported by Okabe & Saishu [Acta Cryst. (2001), E 57 , m251–m252] and not the Zn^II complex. The structure of the title compound is reported here based on data obtained from a twinned crystal.     

Probing the Mechanism of Allylic Substitution of Morita–Baylis–Hillman Acetates (MBHAs) by using the Silyl Phosphonite Paradigm: Scope and Applications of a Versatile Transformation

A P?C bond‐forming reaction between silyl phosphonites and Morita–Baylis–Hillman acetates (MBHAs) is explored as a general alternative towards medicinally relevant β‐carboxyphosphinic structural motifs. Conversion rates of diversely substituted MBHAs to phosphinic acids 9 or 14 that were recorded by using ³¹P NMR spectroscopy revealed unexpected reactivity differences between ester and nitrile derivatives. These kinetic profiles and DFT calculations support a mechanistic scenario in which observed differences can be explained from the “lateness” of transition states. In addition, we provide experimental evidence suggesting that enolates due to initial P‐Michael addition are not formed. Based on the proposed mechanistic scenario in conjunction with DFT calculations, an interpretation of the E/Z stereoselectivity differences between ester and nitriles is proposed. Synthetic opportunities stemming from this transformation are presented, which deal with the preparation of several synthetically capricious phosphinic building blocks, whose access through the classical P‐Michael synthetic route is not straightforward.     

Noise Temperature Increase Effect on Total Outage Analysis of an Interfered Satellite Link

The ever increasing demand for bandwidth and multimedia services has led to the employment of Ka and V band in modern satellite communication networks. In these frequency bands, rain attenuation is the most dominant fading mechanism deteriorating the performance of the Earth-space links. Moreover, interference due to propagation phenomena increases the outage time of the satellite links and should be taken into account for the reliable design of a satellite communication network. In this paper, a physical propagation model for the prediction of carrier-to-noise plus interference ratio statistics of a broadband satellite link incorporating the receiver noise temperature increase due to rain, is presented The obtained numerical results highlight the significance of the latter effect and investigate the impact of various operational, geometrical and climatic parameters in the total outage analysis. Some simple mathematical formulas for the prediction of the carrier-to-noise plus interference ratio, based on the above theoretical results, are also presented.     

Convergence of relaxation schemes to the equations of elastodynamics

We study the effect of approximation matrices to semi-discrete relaxation schemes for the equations of one-dimensional elastodynamics. We consider a semi-discrete relaxation scheme and establish convergence using the theory of compensated compactness. Then we study the convergence of an associated relaxation-diffusion system, inspired by the scheme. Numerical comparisons of fully-discrete schemes are carried out.

     

Experimental synchronization of chaos in diode lasers with polarization-rotated feedback and injection

We demonstrate experimental chaos synchronization between two chaotic semiconductor lasers subjected to polarization-rotated optical feedback and unidirectional injection. This system allows high-quality synchronization to be obtained between dissimilar lasers in a wide range of chaotic operating regimes. Another feature of this system is its operation at high characteristic frequencies, taking advantage of all-optical implementation. Time series and RF spectra showing synchronization are confirmed by high correlation coefficients in excess of 0.85.     

A versatile annulation protocol toward novel constrained phosphinic peptidomimetics

The development of a novel 3-center 2-component annulation reaction between alpha,omega-carbamoylaldehydes and suitably monoalkylated phosphinic acids is reported. Depending on the starting alpha,omega-carbamoylaldehyde, diverse phosphinic scaffolds varying in the size of their rigidity element, the nature and stereochemistry of substituents, and the participation of heteroatoms in the azacyclic ring system can be obtained in one synthetic step and in high yield. In addition, this methodology allows the synthesis of Fmoc-protected constrained aminophosphinic acids that can be easily converted to suitable pseudodipeptide building blocks compatible with the requirements of peptide synthesis on the solid phase. Finally, the careful choice of both substituents and protecting groups can provide functionally diverse, orthogonally protected constrained scaffolds for extended derivatization of the target phosphinic peptidomimetic structures.