Blind Sequential Monte Carlo Joint Tracking of Channel State and Frequency Offset in OFDM Systems

Orthogonal frequency division multiplexing (OFDM) is a multi-carrier modulation scheme, which has been adopted for several wireless standards. In order to fully exploit the benefits of an OFDM system, estimation of the channel state information must be performed. Moreover a well-known problem of OFDM is its sensitivity to frequency offset between the transmitted and received carrier frequencies. This frequency offset introduces inter-carrier interference in the OFDM signal. In this paper we address the problem of jointly tracking the channel and frequency offset based on a Sequential Monte Carlo filtering approach. The proposed algorithm works in a decision-directed way, thus does not require the use of pilot symbols, providing a worth-mentioned increase in the useful data rate. Through simulations we demonstrate the efficiency of this approach against a similar approach where the Extended Kalman Filter is used. Moreover our method is compared with two recently proposed pilot-based methods.     

Structural Properties of Macrodontain I,a Cysteine Protease from <Emphasis Type="Italic">Pseudananas macrodontes</Emphasis> (Morr.) Harms (Bromeliaceae)

The primary structure of macrodontain I, a peptidase from Pseudananas macrodontes fruits, was determined using Edman’s degradation. The enzyme is a non-glycosylated peptidase composed by 213 amino acids with a calculated molecular weight of 23,486.18 Da, pI value 6.99, and a molar extinction coefficient at 280 nm of 61,685 M^?1 cm^?1. The alignment of the sequence of macrodontain I with those cysteine peptidases from species belonging to the family Bromeliaceae showed the highest identity degree (87.74%) against fruit bromelain. A remarkable fact is that all these peptidase sequences show two Met contiguous residues (Met121 and 122) and the nonapeptide VPQSIDWRD located in the mature N-terminal region. Residues Cys26 and His159, which constitute the catalytic dyad in all cysteine peptidases, as well as active site residues Gln20 and Asn176, characteristic of Clan C1A, are conserved in macrodontain I. The 3-D model suggests that the enzyme belongs to the α?+?β class of proteins, with two disulfide bridges (Cys23-Cys63 and Cys57-Cys96) in the α domain, while the β domain is stabilized by another disulfide bridge (Cys153-Cys201). Further, we were able to establish that the cysteine peptidases from P. macrodontes are involved in the anti-inflammatory activity.     

FIB, TEM and LA-ICPMS investigations on melt inclusions in Martian meteorites-Analytical capabilities and geochemical insights

In order to obtain full information coverage on melt inclusions in Martian meteorites (subgroup nakhlites) complementary micro-analytical techniques were used, i.e. focused ion beam, transmission electron microscopy and laser ablation. Using focused ion beam several lamellae for transmission electron microscopy were prepared and secondary electron images of cross-sections could be acquired. Laser ablation–inductively coupled plasma mass spectrometry analyses were performed on selected inclusions to obtain mass-oriented bulk composition of inclusions at depth. The differences in composition between melt inclusions in olivine and augite crystals would suggest a xenocrystic origin for olivine. Furthermore, electron diffraction patterns clearly indicated that the SiO₂-rich phase in inclusions from augite in meteorites from Northwest Africa site is re-crystallized, whereas it is still vitreous in the inclusions from Nakhla sampling site. Therefore, different post-entrapment evolutions were active for the two nakhlite meteorite sets, the Nakhla and the NWA817 set. Melt inclusions in Nakhla olivine presented alteration veins, which were presumably produced before their landing on Earth. If this is the case, this would indicate a alteration stage already on Mars with all the consequence in terms of climate history. Melt inclusions in Nakhla augite resulted unaffected by any alteration or modification following the entrapment, and therefore represent the best candidate to indicate the pristine magma composition.     

Synthesis of Novel Bromophenol with Diaryl Methanes—Determination of Their Inhibition Effects on Carbonic Anhydrase and Acetylcholinesterase

In this work, nine new bromophenol derivatives were designed and synthesized. The alkylation reactions of (2-bromo-4,5-dimethoxyphenyl)methanol (7) with substituted benzenes 8–12 produced new diaryl methanes 13–17. Targeted bromophenol derivatives 18–21 were synthesized via the O-Me demethylation of diaryl methanes with BBr3. Moreover, the synthesized bromophenol compounds were tested with some metabolic enzymes such as acetylcholinesterase (AChE), carbonic anhydrase I (CA I), and II (CA II) isoenzymes. The novel synthesized bromophenol compounds showed Ki values that ranged from 2.53 ± 0.25 to 25.67 ± 4.58 nM against hCA I, from 1.63 ± 0.11 to 15.05 ± 1.07 nM against hCA II, and from 6.54 ± 1.03 to 24.86 ± 5.30 nM against AChE. The studied compounds in this work exhibited effective hCA isoenzyme and AChE enzyme inhibition effects. The results show that they can be used for the treatment of glaucoma, epilepsy, Parkinson’s as well as Alzheimer’s disease (AD) after some imperative pharmacological studies that would reveal their drug potential.     

Threshold parameter estimation in nonadditive non-Gaussian noise

Threshold or weak-signal locally optimum Bayes estimators (LOBEs) of signal parameters, where the observations are an arbitrary mixture of signal and noise, the latter being independent, are first derived for “simple” as well as quadratic cost functions under the assumption that the signal is present a priori. It is shown that the desired LOBEs are either a linear (simple cost function) or a nonlinear (quadratic cost function) functional of an associated locally optimum and asymptotically optimum Bayes detector. Second, explicit classes of (threshold) optimum estimators are obtained for both cost functions in the coherent as well as in the incoherent reception modes. Third, the general results are applied to amplitude estimation, where two examples are considered: (1) coherent amplitude estimation in multiplicative noise with simple cost function (SCF) and (2) incoherent amplitude estimation with quadratic cost function (QFC) of a narrowband signal arbitrarily mixed with noise. Moreover, explicit estimator structures are given together with desired properties (i.e. efficiency of the unconditional maximum likelihood (ML) estimator) and Bayes' risks. These properties are obtained by employing contiguity-a powerful concept in modern statistics-implied by the locally asymptotically normal character of the detection algorithms     

Alternative,High‐Yield Synthesis of (E)‐4‐Oxonon‐2‐enoic Acid from 2‐Methoxyfuran

Alkylation of 2‐methoxyfuran, followed by in situ TPP‐sensitized photooxygenation of 2‐methoxy‐5‐pentylfuran in the presence of Me₂S, gave methyl (Z)‐4‐oxonon‐2‐enoate. Hydrolysis of methyl (Z)‐4‐oxonon‐2‐enoate afforded (E)‐4‐oxonon‐2‐enoic acid in three steps and in 79% overall yield.     

Adaptive nonparametric locally optimum Bayes detection in additive non-Gaussian noise

A nonparametric generalization of the locally optimum Bayes (LOB) parametric theory of signal detection in additive non-Gaussian noise with independent sampling is presented. From a locally asymptotically normal (LAN) expansion of the log-likelihood ratio the nonparametric detector structure, in both coherent and incoherent modes, is determined. Moreover, its statistics under both hypotheses are obtained. The nonparametric LAN log-likelihood ratio is then reduced to a least informative (i.e., having minimum variance under the hypothesis, H/sub 0/) local parametric submodel, which is referred to as adaptive. In the adaptive submodel, certain nonlinearities are replaced by their efficient estimates. This is accomplished such that no information is lost when the noise first-order density is no longer parametrically defined. Adaptive nonparametric LOB detectors are thus shown to be asymptotically optimum (AO), canonical in signal waveform, distribution free in noise statistics, and identical in form (in the symmetric cases) to their parametric counterparts. A numerical example is provided when the underlying density is Middleton's (see ibid., vol.45, p.1129-49, May 1999)Class-A noise, which demonstrates that even with a relatively small sample size (O(10/sup 2/)) adaptive LOB nonparametric detectors perform nearly as well as the classical LOB detectors.