Channel Estimation Method for OFDM in Low SNR Based on Two-dimensional Spreading

In this paper, we present a channel estimation method based on two-dimensional signal spreading applicable to orthogonal frequency multiple access multicarrier systems. Our method exploits a spreading of a transmitted data signal as well as a pilot signal over the assigned frequency range and time period. As a spreading sequence we exploited orthogonal Walsh–Hadamard sequences. When compared with traditional pilot symbol based channel estimation, our method is beneficial in low signal to noise ratio (SNR). For a comparison of our method with state-of-the-art channel estimation method, we utilized an open source LTE downlink simulator developed at TU Vienna. This enables a reproducibility of our results. Considering the LTE system, our method outperforms the traditional approach in typical range of SNR from \(-\) 5 to 10 dB. For a comparison of a throughput performance, a number of channel models has been employed.     

Effect of Different Polymeric Matrices on Some Properties of Plastic Bonded Explosives

Matrices based on polyisobutylene (PIB), polymethyl‐methacrylate (PA), Viton A 200, Dyneon FT 2481 (Fluorel), and polydimethyl‐siloxane binders were studied as desensitizers. A series of plastic explosives (PBXs) were prepared, based on four different nitramines, namely RDX (1,3,5‐trinitro‐1,3,5‐triazinane), β‐HMX (β‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane), BCHMX (cis‐1,3,4,6‐tetranitro‐octahydroimidazo‐[4,5‐d]imidazole) and ε‐HNIW (ε‐2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane, ε‐CL‐20), bonded by the matrices mentioned. For comparison, pentaerythritol tetranitrate and certain commercial explosives based on it, Semtex 1A, Semtex 10 and Sprängdeg m/46, were used. Detonation velocities, sensitivities to impact and friction, and peak temperatures of thermal decomposition by differential thermal analysis technique (DTA) for all the explosives studied were determined. Heat of detonation was calculated by means of a thermodynamic calculation program (EXPLO 5 code). Fluoroelastomers have a neutral to positive effect on the thermal stability of nitramines and they have a significant effect on decreasing the friction sensitivity. However, their anti‐impact efficiency is the lowest in this study although they have a positive effect on performance of the corresponding PBXs. PA and PIB matrices markedly decrease thermal stability of nitramines, the anti‐impact influences of PIB‐binders are better than those of PA‐binders, while PA‐binders have a higher anti‐friction effect and slightly less negative influence on the performance of the PBXs in comparison with PIB mixtures. The polydimethyl‐siloxane matrix has a neutral effect on thermal stability of the nitramines studied, it has an influence on the volume thermochemistry of detonation comparable with that of fluoroelastomers although it does not provide comparable performance, and its corresponding PBXs have optimum sensitivity parameters.     

Aerosol counterflow two-jets unit for continuous measurement of the soluble fraction of atmospheric aerosols

A new type of aerosol collector employing a liquid at laboratory temperature for continuous sampling of atmospheric particles is described. The collector operates on the principle of a Venturi scrubber. Sampled air flows at high linear velocity through two Venturi nozzles "atomizing" the liquid to form two jets of a polydisperse aerosol of fine droplets situated against each other. Counterflow jets of droplets collide, and within this process, the aerosol particles are captured into dispersed liquid. Under optimum conditions (air flow rate of 5 L/min and water flow rate of 2 mL/min), aerosol particles down to 0.3 microm in diameter are quantitatively collected in the collector into deionized water while the collection efficiency of smaller particles decreases. There is very little loss of fine aerosol within the aerosol counterflow two-jets unit (ACTJU). Coupling of the aerosol collector with an annular diffusion denuder located upstream of the collector ensures an artifact-free sampling of atmospheric aerosols. Operation of the ACTJU in combination with on-line detection devices allows in situ automated analysis of water-soluble aerosol species (e.g., NO2-, NO3-)with high time resolution (as high as 1 s). Under the optimum conditions, the limit of detection for particulate nitrite and nitrate is 28 and 77 ng/m(3), respectively. The instrument is sufficiently rugged for its application at routine monitoring of aerosol composition in the real time.     

Sarcosine as a Potential Prostate Cancer Biomarker—A Review

Prostate cancer (CaP) is the most common type of tumour disease in men. Early diagnosis of cancer of the prostate is very important, because the sooner the cancer is detected, the better it is treated. According to that fact, there is great interest in the finding of new markers including amino acids, proteins or nucleic acids. Prostate specific antigen (PSA) is commonly used and is the most important biomarker of CaP. This marker can only be detected in blood and its sensitivity is approximately 80%. Moreover, early stages cannot be diagnosed using this protein. Currently, there does not exist a test for diagnosis of early stages of prostate cancer. This fact motivates us to find markers sensitive to the early stages of CaP, which are easily detected in body fluids including urine. A potential is therefore attributed to the non-protein amino acid sarcosine, which is generated by glycine-N-methyltransferase in its biochemical cycle. In this review, we summarize analytical methods for quantification of sarcosine as a CaP marker. Moreover, pathways of the connection of synthesis of sarcosine and CaP development are discussed.     

Fusarium mycotoxins in various barley cultivars and their transfer into malt

BACKGROUND: Fusarium toxins, secondary metabolites of toxinogenic Fusarium species, are found in a range of cereal grains. In this study the occurrence of the most commonest Fusarium toxins, namely nivalenol (NIV), deoxynivalenol (DON), deoxynivalenol‐3‐glucoside, fusarenon‐X, 3‐ and 15‐acetyldeoxynivalenol, HT‐2 and T‐2 toxins and zearalenone, in various barley cultivars harvested in 2005–2008 was monitored. The impact of weather, locality, fungicide treatment and barley cultivar (hulless or covered) on contamination was evaluated. The transfer of these mycotoxins into malt was assessed. RESULTS: The most prevalent toxin was DON, which was found in 83% of samples (maximum level 180 µg kg^?1), while HT‐2 was detected in 62% of samples (maximum level 716 µg kg^?1). Using analysis of covariance, weather was found to be the key factor in all years (P < 0.001). A relationship between cultivar and contamination was confirmed only for HT‐2 (P < 0.001) and T‐2 (P = 0.037), with higher levels of these toxins being observed in hulless cultivars. With the exception of NIV (P = 0.008), no significant relationship was found between fungicide treatment and contamination. No distinct trend regarding DON levels in malt was found, with both decreases and increases occurring. CONCLUSION: The results show an inter‐annual variation in mycotoxin occurrence in barley cultivars as well as differences in contamination of malt produced from fungicide‐treated and untreated barley. Copyright © 2010 Society of Chemical Industry     

Traffic Control in ATM Networks

Editor's Note: Zbynek Bazanowski is a doctoralcandidate specializing in managing high-speed networks.I met him in St. Petersburg where he gave an excellenttalk on managing ATM networks and he has done important work in understanding the dynamicbehavior of ATM networks under load. I worry that thecontrol mechanisms for high-speed networks mustanticipate bottlenecks, and relying on feedback control will lead to servo lags that will make thesenetworks inherently unstable when they regularly exceed40% utilization. This is real and not a theoreticalproblem demonstrated by the September, 1995 INTERNETtraffic jams. Here is Zbynek's prognosis on managingthese high-speed networks.     

Maximizing the Efficiency of Multienzyme Process by Stoichiometry Optimization

Multienzyme processes represent an important area of biocatalysis. Their efficiency can be enhanced by optimization of the stoichiometry of the biocatalysts. Here we present a workflow for maximizing the efficiency of a three‐enzyme system catalyzing a five‐step chemical conversion. Kinetic models of pathways with wild‐type or engineered enzymes were built, and the enzyme stoichiometry of each pathway was optimized. Mathematical modeling and one‐pot multienzyme experiments provided detailed insights into pathway dynamics, enabled the selection of a suitable engineered enzyme, and afforded high efficiency while minimizing biocatalyst loadings. Optimizing the stoichiometry in a pathway with an engineered enzyme reduced the total biocatalyst load by an impressive 56 %. Our new workflow represents a broadly applicable strategy for optimizing multienzyme processes.     

Effects of post-crosslinking of macroreticular styrene-divinylbenzene copolymers on their morphology

We performed a detailed comparison of properties of two different styrenic polymers containing divinylbenzene as the crosslinker before and after the introduction of the additional crosslinks by Friedel-Craft's reaction of the residual double bonds. For the polymer characterization was used a wide selection of methods, including nitrogen adsorption/desorption, inverse steric exclusion chromatography, MAS NMR and AFM. The residual double bonds are quite probably located in the dense cores of the microgel domains where steric hindrances prevented them to react during the polymerization. Reinforcement of the cores of polymer microgel domains by transformation of the residual double bonds into additional crosslinks by the Friedel-Craft's reaction results then in greater stability of the already existing pores rather than in creation of new pores by incomplete collapse of swollen polymer gel.     

Numerical modelling as a tool for optimisation of sub-slab depressurisation systems design

The following paper is focused on possibilities of a numerical modelling of sub-slab depressurisation systems, which belong among the most effective radon protective measures. Three recently developed computer programs are briefly described in the paper—mainly from the point of view of governing equations and basic numerical analysis approach. The paper also presents results of sensitivity tests for these numerical models. In addition, a comparison of numerical simulation results with measured data is included as well.