Space time block code classification for MIMO signals exploiting cyclostationarity

Blind and noncooperative identification of the transmission parameters of unknown communication signals has been employed both in military and civilian applications. Multiple-Input-Multiple-Output (MIMO) transmission systems emerging in the last decade pose new challenges to the signal identification systems, one of which is the identification of the Space-Time Block Code (STBC) used in the transmission. In this work, we present a novel STBC classification algorithm that exploits the joint wide sense cyclostationary characteristics of the coded transmit signals as discriminating features. Compared to existing algorithms, the proposed method can discriminate between a large number of different STBCs

Neuro-protective effects of Crocin on brain and cerebellum tissues in diabetic rats

Background: Increase in free oxygen radicals and the disruption of defense system make the neurons and astrocytes more sensitive against oxidative damage.Materials and Methods: Rats were divided into three groups containing 10, rats in each group namely: control (C) group, Diabetes Mellitus (DM) group, and Diabetes Mellitus + crocin (DM+crocin) group. Tissue samples were processed by routine histological and biochemical procedures. The sections were stained with Hematoxylen-eosin. Malondialdehyde (MDA), glutathione (GSH), blood glucose, HbA1c levels and xanthine oxidase (XO) activities were assayed.Results: The histological appearence of the cerebrum and cerebellum were normal in the control group. DM group showed some histopathological changes including congestion, perivascular and perineuronal edema in cerebrum. In DM + crocin group, histopathological changes in cerebrum and cerebellum markedly reduced. MDA level and XO activities increased significantly in DM group (P<0.01), but decreased significantly in DM + crocin group when compared to DM group (P<0.01). Blood glucose concentrations increased significantly (p<0.01) in DM group), but decreased significantly in DM + crocin group when compared with DM group (p<0.05). Blood HbA1c levels were normal in control group. But there were significant differences between control and DM groups (p<0.01). On the other hand, blood HbA1c levels decreased in DM+crocin group when compared with the DM group, but it was not statistically significant (p > 0.05).Conclusion: Due to the fact that crocin has an antioxidant and anti-hyperglycemic effects, it can protect the brain and cerebellum tissue  against the complications of oxidative stress.Key words: Diabetes mellitus, oxidative stress, crocin, brain, cerebellum

Effects of the acute exposure to the electromagnetic field of mobile phones on human auditory brainstem responses

The purpose of this study was to evaluate the short-term effects of the electromagnetic fields (EMF) of mobile phones on human auditory brainstem responses. This prospective study of healthy adults evaluated the influence of EMF. Eighteen healthy adult volunteers participated in this study. Mobile telephones emitting signals in the region of 900MHz and with the highest SAR value of 0.82W/kg were positioned in direct contact to the right ear, which was exposed to the phone signal for 15min before and after ABR testing with click stimuli of 60 and 80dB nHL intensities. The latencies of the waves and interwave latencies were measured on screen by an experienced audiologist. The differences of the mean latencies of waves I, III and IV were not significant in initial and post-exposure ABR measurements at both 60 and 80dB nHL stimulus levels ( P >0.05). Similarly, differences of the mean interwave intervals I-III, I-V and III-V remained insignificant at the initial and postexposure ABR measurements at stimulus levels of both 60 and 80dB nHL ( P >0.05). Acute exposure to the EMF of mobile phones does not cause perturbations in ABR latencies. However, these negative results should not encourage excessive mobile communication, because minor biological and neurophysiological influences may not be detectable by the current technolog

Comments on Sweeny and Gliozzi dynamics for simulations of Potts models in the Fortuin-Kasteleyn representation

We compare the correlation times of the Sweeny and Gliozzi dynamics for two-dimensional Ising and three-state Potts models, and the three-dimensional Ising model for the simulations in the percolation prepresentation. The results are also compared with Swendsen-Wang and Wolff cluster dynamics. It is found that Sweeny and Gliozzi dynamics have essentially the same dynamical critical behavior. Contrary to Gliozzi's claim (cond-mat/0201285), the Gliozzi dynamics has critical slowing down comparable to that of other cluster methods. For the two-dimensional Ising model, both Sweeny and Gliozzi dynamics give good fits to logarithmic size dependences; for two-dimensional three-state Potts model, their dynamical critical exponent z is 0.49(1); the three-dimensional Ising model has z = 0.37(2).Comment: RevTeX, 4 pages, 5 figure

Magnetic and electrical properties of NdNiSn

Magnetization and resistivity measurements have been carried out on the equiatomic ternary compound NdNiSn in the temperature range 2–200 K. The compound crystallizes in the orthorhombic CeNiSn-type structure with space group Pna21. Magnetic susceptibility shows a distinct feature at TN=3 K (Néel temperature), typical of a phase transition from an antiferromagnetic to paramagnetic state. In the paramagnetic regime, the magnetic susceptibility obeys Curie–Weiss behavior yielding an effective magnetic moment μeff=3.32μB at lower temperatures, and 3.88 μB at higher temperatures. The reduction in the magnetic moment at lower temperatures is attributed to a crystalline electric field (CEF) effect, while the slight excess of magnetic moment at high temperatures compared to that of the free Nd3+ ion (3.62 μB) indicates that only a very small magnetic moment, at most 0.3 μB, is induced at the Ni sites. The electrical resistivity exhibits metallic behavior and no anomaly is observed at the respective Néel temperature. Analysis of the resistivity data in terms of crystalline electric fields including s–d electron scattering reveals that the ground magnetic state for the Nd3+ ions is a doublet of J=±5/2 states, with a first exited doublet of J=±7/2 states having an energy splitting of 56 K, with the next exited multiplet 139 K above the ground levels. These results are in fairly good agreement with those reported in the literature based on magnetic susceptibility and heat capacity measurements

Effect of exchange bias on the electrical resistivity of Pd doped NiMn thin films: Two-Channel Kondo system

Electrical resistivity measurements have been carried out for both flash-evaporated reentrant spin glasses (RSGs) (Ni76−xPdx)Mn24 and Ni74.5Mn23.5Pd2, as well as Ni75Mn23Pd2, a pure SG. These measurements were carried out at temperatures down to 4K. We observed a very deep resistivity minimum at about 75K for Ni74Mn24Pd2. It was found previously [Öner et al., J. Appl. Phys.89, 7044 (2001)] that this sample shows the largest coercivity and exchange unidirectional anisotropy among these films. In addition, magnetization measurements show that this takes place just on the border of the RSG such that it could be handled as a superparamagnetic sample. Previously it was assumed that the exchange bias created in the sample between the domains plays the dominant role in the resistivity minimum. On the other hand, in order to account for the temperature dependence of the resistivity below the minimum we have analyzed these data using the Kondo, two-channel Kondo, weak localization, and Cochrane models for structural disorder based on the Anderson mechanism. We have deduced that the two-channel Kondomodel gives the best agreement with the data; a logarithmic temperature dependence Δρ(T)=βlog10(T∕TK), was observed at the temperatures below Tf accompanied by a resistivity behavior Δρ(T)=ρ0m(0)(1−αT1∕2), at lower temperatures. All parameters deduced from the fitting correlate consistently with the strength of the exchange anisotropy and coercivity in the RSG films, and thus provide a separate measure of the presence of antiferromagnetically coupled domains in these materials