Editorial

In the past years, digital signal processing (DSP) algorithms and architectures for baseband communication systems have fuelled the delivery of applications such as 3G mobile communications and wireless LAN to mass markets. This was made possible by a tremendous growth in the performance of computational devices such as digital signal processors and FPGAs, as well as an increase in sampling rates of conversion devices to potentially several 100 MHz. While the development of both computational devices and ADCs/DACs continues, thus permitting DSP to be applied at IF sampling rates and possibly beyond, the opportunities for further enhancing radio devices by DSP algorithms and architectures arise. Against this background of development, an IEE/EURASIP conference on “DSP-Enabled Radio” was held at the Institute for System Level Integration (ISLI) in Livingston, Scotland, in September 2003. This very lively one-and-ahalf- day event brought together 120 researchers from both industry and academia with a strong international participation. It was the spirit of this DSP-Enabled Radio conference and the contributions therein that brought to life the idea to this special issue. This issue contains both contributions from the event and responses to an open call for papers

Combining Localization Cues and Source Model Constraints for Binaural Source Separation

We describe a system for separating multiple sources from a two-channel recording based on interaural cues and prior knowledge of the statistics of the underlying source signals. The proposed algorithm effectively combines information derived from low level perceptual cues, similar to those used by the human auditory system, with higher level information related to speaker identity. We combine a probabilistic model of the observed interaural level and phase differences with a prior model of the source statistics and derive an EM algorithm for finding the maximum likelihood parameters of the joint model. The system is able to separate more sound sources than there are observed channels in the presence of reverberation. In simulated mixtures of speech from two and three speakers the proposed algorithm gives a signal-to-noise ratio improvement of 1.7 dB over a baseline algorithm which uses only interaural cues. Further improvement is obtained by incorporating eigenvoice speaker adaptation to enable the source model to better match the sources present in the signal. This improves performance over the baseline by 2.7 dB when the speakers used for training and testing are matched. However, the improvement is minimal when the test data is very different from that used in training

The interferon-induced exonuclease ISG20 exerts antiviral activity through upregulation of type I interferon response proteins

The host immune responses to infection lead to the production of type I interferon (IFN), and the upregulation of interferon-stimulated genes (ISGs) reduces virus replication and virus dissemination within a host. Ectopic expression of the interferon-induced 20-kDa exonuclease ISG20 suppressed replication of chikungunya virus and Venezuelan equine encephalitis virus, two mosquito-vectored RNA alphaviruses. Since the replication of alphavirus genomes occurs exclusively in the cytoplasm, the mechanism of nucleus-localized ISG20 inhibition of replication is unclear. In this study, we determined that ISG20 acts as a master regulator of over 100 genes, many of which are ISGs. Specifically, ISG20 upregulated IFIT1 genes and inhibited translation of the alphavirus genome. Furthermore, IFIT1-sensitive alphavirus replication was increased in Isg20−/− mice compared to the replication of wild-type viruses but not in cells ectopically expressing ISG20. We propose that ISG20 acts as an indirect regulator of RNA virus replication in the cytoplasm through the upregulation of many other ISGs.Type I interferon (IFN)-stimulated genes (ISGs) have critical roles in inhibiting virus replication and dissemination. Despite advances in understanding the molecular basis of ISG restriction, the antiviral mechanisms of many remain unclear. The 20-kDa ISG ISG20 is a nuclear 3′–5′ exonuclease with preference for single-stranded RNA (ssRNA) and has been implicated in the IFN-mediated restriction of several RNA viruses. Although the exonuclease activity of ISG20 has been shown to degrade viral RNA in vitro, evidence has yet to be presented that virus inhibition in cells requires this activity. Here, we utilized a combination of an inducible, ectopic expression system and newly generated Isg20−/− mice to investigate mechanisms and consequences of ISG20-mediated restriction. Ectopically expressed ISG20 localized primarily to Cajal bodies in the nucleus and restricted replication of chikungunya and Venezuelan equine encephalitis viruses. Although restriction by ISG20 was associated with inhibition of translation of infecting genomic RNA, degradation of viral RNAs was not observed. Instead, translation inhibition of viral RNA was associated with ISG20-induced upregulation of over 100 other genes, many of which encode known antiviral effectors. ISG20 modulated the production of IFIT1, an ISG that suppresses translation of alphavirus RNAs. Consistent with this observation, the pathogenicity of IFIT1-sensitive alphaviruses was increased in Isg20−/− mice compared to that of wild-type viruses but not in cells ectopically expressing ISG20. Our findings establish an indirect role for ISG20 in the early restriction of RNA virus replication by regulating expression of other ISGs that inhibit translation and possibly other activities in the replication cycle

Source Separation Based on Binaural Cues and Source Model Constraints

We describe a system for separating multiple sources from a two-channel recording based on interaural cues and known characteristics of the source signals. We combine a probabilistic model of the observed interaural level and phase differences with a prior model of the source statistics and derive an EM algorithm for finding the maximum likelihood parameters of the joint model. The system is able to separate more sound sources than there are observed channels. In simulated reverberant mixtures of three speakers the proposed algorithm gives a signal-to-noise ratio improvement of 2.1 dB over a baseline algorithm using only interaural cues

Rigorous Born Approximation and beyond for the Spin-Boson Model

Within the lowest-order Born approximation, we present an exact calculation of the time dynamics of the spin-boson model in the ohmic regime. We observe non-Markovian effects at zero temperature that scale with the system-bath coupling strength and cause qualitative changes in the evolution of coherence at intermediate times of order of the oscillation period. These changes could significantly affect the performance of these systems as qubits. In the biased case, we find a prompt loss of coherence at these intermediate times, whose decay rate is set by $\sqrt{\alpha}$, where $\alpha$ is the coupling strength to the environment. We also explore the calculation of the next order Born approximation: we show that, at the expense of very large computational complexity, interesting physical quantities can be rigorously computed at fourth order using computer algebra, presented completely in an accompanying Mathematica file. We compute the $O(\alpha)$ corrections to the long time behavior of the system density matrix; the result is identical to the reduced density matrix of the equilibrium state to the same order in $\alpha$. All these calculations indicate precision experimental tests that could confirm or refute the validity of the spin-boson model in a variety of systems.Comment: Greatly extended version of short paper cond-mat/0304118. Accompanying Mathematica notebook fop5.nb, available in Source, is an essential part of this work; it gives full details of the fourth-order Born calculation summarized in the text. fop5.nb is prepared in arXiv style (available from Wolfram Research

Physical characteristics and non-keplerian orbital motion of "propeller" moons embedded in Saturn's rings

We report the discovery of several large "propeller" moons in the outer part of Saturn's A ring, objects large enough to be followed over the 5-year duration of the Cassini mission. These are the first objects ever discovered that can be tracked as individual moons, but do not orbit in empty space. We infer sizes up to 1--2 km for the unseen moonlets at the center of the propeller-shaped structures, though many structural and photometric properties of propeller structures remain unclear. Finally, we demonstrate that some propellers undergo sustained non-keplerian orbit motion. (Note: This arXiv version of the paper contains supplementary tables that were left out of the ApJL version due to lack of space).Comment: 9 pages, 4 figures; Published in ApJ

Tapering practices of New Zealand's elite raw powerlifters

Pritchard, HJ, Tod, DA, Barnes, MJ, Keogh, JW, and McGuigan, MR. Tapering practices of New Zealand's elite raw powerlifters. J Strength Cond Res 30(7): 1796-1804, 2016-The major aim of this study was to determine tapering strategies of elite powerlifters. Eleven New Zealand powerlifters (28.4 ± 7.0 years, best Wilks score of 431.9 ± 43.9 points) classified as elite were interviewed, using semistructured interviews, about their tapering strategies. Interviews were transcribed verbatim and content analyzed. Total training volume peaked 5.2 ± 1.7 weeks from competition while average training intensity (of 1 repetition maximum) peaked 1.9 ± 0.8 weeks from competition. During tapering, volume was reduced by 58.9 ± 8.4% while intensity was maintained (or slightly reduced) and the final weight training session was performed 3.7 ± 1.6 days out from competition. Participants generally stated that tapering was performed to achieve full recovery; that accessory work was removed around 2 weeks out from competition; and deadlifting takes longer to recover from than other lifts. Typically participants stated that trial and error, and changes based on "feel" were the sources of tapering strategies; equipment used and movements performed during tapering are the same as in competition; nutrition was manipulated during the taper (for weight cutting or performance aims); and poor tapering occurred when too long (1 week or more) was taken off training. These results suggest that athletes may benefit from continuing to strength train before important events with reduced volume and maintained intensity. Only exercises that directly assist sports performance should remain in the strength program during tapering, to assist with reductions in fatigue while maintaining/improving strength expression and performance

Nocturia as an Unrecognized Symptom of Uncontrolled Hypertension in Black Men Aged 35 to 49 Years.

Background Hypertension is assumed to be asymptomatic. Yet, clinically significant nocturia (≥2 nightly voids) constitutes a putative symptom of uncontrolled hypertension. Black men with hypertension may be prone to nocturia because of blunted nocturnal blood pressure ( BP ) dipping, diuretic drug use for hypertension, and comorbidity that predisposes to nocturia. Here, we test the hypothesis that nocturia is a common and potentially reversible symptom of uncontrolled hypertension in black men. Methods and Results We determined the strength of association between nocturia (≥2 nightly voids) and high BP (≥135/85 mm Hg) by conducting in-person health interviews and measuring BP with an automated monitor in a large community-based sample of black men in their barbershops. Because nocturia is prevalent and steeply age-dependent after age 50 years, we studied men aged 35 to 49 years. Among 1673 black men (mean age, 43±4 years [ SD ]), those with hypertension were 56% more likely than men with normotension to have nocturia after adjustment for diabetes mellitus and sleep apnea (adjusted odds ratio, 1.56; 95% CI , 1.25-1.94 [ P<0.0001]). Nocturia prevalence varied by hypertension status, ranging from 24% in men with normotension to 49% in men whose hypertension was medically treated but uncontrolled. Men with untreated hypertension were 39% more likely than men with normotension to report nocturia ( P=0.02), whereas men whose hypertension was treated and controlled were no more likely than men with normotension to report nocturia ( P=0.69). Conclusions Uncontrolled hypertension was an independent determinant of clinically important nocturia in a large cross-sectional community-based study of non-Hispanic black men aged 35 to 49 years. Clinical Trial Registration URL : http://www.clinicaltrials.gov . Unqiue identifier: NCT 02321618

MOST photometry of the RRd Lyrae variable AQ Leo: Two radial modes, 32 combination frequencies, and beyond

Highly precise and nearly uninterrupted optical photometry of the RR Lyrae star AQ Leo was obtained with the MOST (Microvariability & Oscillations of STars) satellite over 34.4 days in February-March 2005. AQ Leo was the first known double-mode RR Lyrae pulsator (RRd star). Three decades after its discovery, MOST observations have revealed that AQ Leo oscillates with at least 42 frequencies, of which 32 are linear combinations (up to the sixth order) of the radial fundamental mode and its first overtone. Evidence for period changes of these modes is found in the data. The other intrinsic frequencies may represent an additional nonradial pulsation mode and its harmonics (plus linear combinations) which warrant theoretical modeling. The unprecedented number of frequencies detected with amplitudes down to millimag precision also presents an opportunity to test nonlinear theories of mode growth and saturation in RR Lyrae pulsators.Comment: accepted for publication in MNRAS; revision v2 : broken references have been fixe