Low-level Interference Research Articles

Interference from long-tailed finches constrains reproduction in the endangered Gouldian finch

1. Interspecific interference competition for nest-sites among cavity-nesting birds can have important effects on reproductive fitness and the distribution of competing species. 2. We observed interference at nest-sites in free-living populations of the endangered Gouldian finch (Erythrura gouldiae) and sympatric long-tailed finch (Poephila acuticauda), and also experimentally tested the relative strength and effect of interference at nest-sites in captive populations. 3. Levels of competitive interference at nest-sites in the wild were high for Gouldian, but not long-tailed finches, and interference frequency was inversely related to Gouldian finch reproductive success. High levels of interference conferred reduced fledging success but did not affect offspring condition. 4. Captive experiments corroborated the field data, also demonstrating fitness costs of interspecific competition, and that long-tailed finches dominated resources under standardized conditions. 5. Such asymmetrical competition dynamics are likely to constrain reproduction in Gouldian finch populations, potentially affecting recruitment and hindering the recovery of remaining populations of this endangered species.

Theta Oscillations Reflect the Dynamics of Interference in Episodic Memory Retrieval

Selectively retrieving episodic information from a cue often induces interference from related episodes. To promote successful retrieval of the target episode, such interference is resolved by inhibition, causing retrieval-induced forgetting of the related but irrelevant information. Passively studying the episodic information again (reexposure) does not show this effect. This study examined the hypothesis that brain oscillations in the theta band (5-9 Hz) reflect the dynamics of interference in selective memory retrieval, analyzing EEG data from 24 healthy human subjects (21 women, 3 men). High versus low levels of interference were investigated by comparing the effects of selective retrieval with the effects of reexposure of material, with the former, but not the latter, inducing interference. Moreover, we analyzed repeated cycles of selective retrieval and reexposure, assuming that interference is reduced by inhibition across retrieval cycles, but not across reexposure cycles. We found greater theta band activity in selective retrieval than in reexposure, and a reduction in theta amplitude from the first to the second cycle of retrieval predicting the amount of retrieval-induced forgetting; the sources of theta amplitude reduction across retrieval cycles were located in the anterior cingulate cortex. No difference in theta activity was found across repeated cycles of reexposure. The results suggest that higher levels of interference in episodic memory are indexed by more theta band activity, and that successful interference resolution via inhibition causes a reduction in theta amplitude. Thus, theta band activity can serve as a neural marker of the dynamics of interference in selective episodic retrieval.

A highly sensitive and selective dimethyl ether sensor based on cataluminescence

A sensor for detecting dimethyl ether was designed based on the cataluminescence phenomenon when dimethyl ether vapors were passing through the surface of the ceramic heater. The proposed sensor showed high sensitivity and selectivity to dimethyl ether at an optimal temperature of 279 °C. Quantitative analysis were performed at a wavelength of 425 nm, the flow rate of carrier air is around 300 mL/min. The linear range of the cataluminescence intensity versus concentration of dimethyl ether is 100–6.0 × 10 3 ppm with a detection limit of 80 ppm. The sensor response time is 2.5 s. Under the optimized conditions, none or only very low levels of interference were observed while the foreign substances such as benzene, formaldehyde, ammonia, methanol, ethanol, acetaldehyde, acetic acid, acrolein, isopropyl ether, ethyl acetate, glycol ether and 2-methoxyethanol were passing through the sensor. Since the sensor does not need to prepare and fix up the granular catalyst, the simple technology reduces cost, improves stability and extends life span. The method can be applied to facilitate detection of dimethyl ether in the air. The possible mechanism of cataluminescence from the oxidation of dimethyl ether on the surface of ceramic heater was discussed based on the reaction products.

Q-Bursts: Natural ELF Radio Transients

We overview resonance spectra and present analytical expressions for the waveforms of natural extremely low frequency transient events (Q-bursts). It is shown that model and observed waveforms are similar when a wideband receiver is used at a place with low level of industrial interference. We also describe how to detect a natural ELF transient signal embedded in the man-made noise by using the singular spectral analysis.

Financial, vocational, and interpersonal impact of living liver donation

The ability to inform prospective donors of the psychosocial risks of living liver donation is currently limited by the scant empirical literature. The present study was designed to examine donor perceptions of the impact of donation on financial, vocational, and interpersonal life domains and identify demographic and clinical factors related to longer recovery times and greater life interference. A total of 143 donors completed a retrospective questionnaire that included a standardized measure of life interference [Illness Intrusiveness Rating Scale (IIRS)] and additional questions regarding the perceived impact of donation. Donor IIRS scores suggested that donors experience a relatively low level of life interference due to donation [1.60 +/- 0.72, with a possible range of 1 ("not very much" interference) to 7 ("very much" interference)]. However, approximately 1 in 5 donors reported that donating was a significant financial burden. Logistic regression analysis revealed that donors with a psychiatric diagnosis at or prior to donation took longer to return to their self-reported predonation level of functioning (odds ratio = 3.78, P = 0.016). Medical complications were unrelated to self-reported recovery time. Multiple regression analysis revealed 4 independent predictors of greater life interference: less time since donation (b = 0.11, P < 0.001), income lower than CAD$100,000 (b = 0.28, P = 0.038), predonation concerns about the donation process (b = 0.24, P = 0.008), and the perception that the recipient is not caring for the new liver (b = 0.12, P = 0.031). In conclusion, life interference due to living liver donation appears to be relatively low. Donors should be made aware of risk factors for greater life disruptions post-surgery and of the potential financial burden of donation.

A novel gaseous dimethylamine sensor utilizing cataluminescence on zirconia nanoparticles

A novel cataluminescence (CTL) sensor using ZrO2 nanoparticles as the sensing material was developed for the determination of trace dimethylamine in air samples based on the catalytic chemiluminescence (CL) of dimethylamine on the surface of ZrO2 nanoparticles. The CTL characteristics and the different factors on the signal intensity for the sensor, including nanomaterials, working temperature, wavelength and airflow rate, were investigated in detail. The CL intensity on ZrO2 nanoparticles was the strongest among the seven examined catalysts. This novel CL sensor showed high sensitivity and selectivity to gaseous dimethylamine at optimal temperature of 330 degrees C. Quantitative analysis was performed at a wavelength of 620 nm. The linear range of CTL intensity vs concentration of gaseous dimethylamine was 4.71 x 10(-3) to 7.07 x 10(-2 )mg L(-1) (r = 0.9928) with a detection limit (3sigma) of 6.47 x 10(-4) mg L(-1). No or only very low levels of interference were observed while the foreign substances such as benzene, hydrochloric acid, methylbenzene, chloroform, n-hexane and water vapor were passing through the sensor. The response time of the sensor was less than 50 s, and the sensor had a long lifetime of more than 60 h. The sensor was successfully applied to the determination of dimethylamine in artificial air samples, and could potentially be applied to analysis of nerve agents such as Tabun (GA).

Relational support from friends and wives' family relationships: The role of husbands' interference

Informed by Marks's three corners model, this study explored the moderating role of husbands' relational interference in the link between relational support from close friends and wives' marital and family relationship quality. Using data from 52 wives rearing school-aged children, results from a hierarchical regression analysis suggested that husbands' interference moderates the association between support from close friends and both wives' marital satisfaction and mother—child relationship quality. At low levels of interference from husbands, support from close friends is positively associated with wives' reports of marital satisfaction, and at high levels of spousal interference, support from close friends is positively associated with mother—child relationship quality. Theoretical implications for studying these processes as they co-occur across multiple close relationships are discussed.

Capacity Optimization for Local and Cooperative Spectrum Sensing in Cognitive Radio Networks

The dynamic spectrum allocation solutions such as cognitive radio networks have been proposed as a key technology to exploit the frequency segments that are spectrally underutilized. Cognitive radio users work as secondary users who need to constantly and rapidly sense the presence of primary users or licensees to utilize their frequency bands if they are inactive. Short sensing cycles should be run by the secondary users to achieve higher throughput rates as well as to provide low level of interference to the primary users by immediately vacating their channels once they have been detected. In this paper, the throughput-sensing time relationship in local and cooperative spectrum sensing has been investigated under two distinct scenarios, namely, constant primary user protection (CPUP) and constant secondary user spectrum usability (CSUSU) scenarios. The simulation results show that the design of sensing slot duration is very critical and depends on the number of cooperating users under CPUP scenario whereas under CSUSU, cooperating more users has no effect if the sensing time used exceeds 5% of the total frame duration.

Altering Presenilin Gene Activity in Zebrafish Embryos Causes Changes in Expression of Genes with Potential Involvement in Alzheimer's Disease Pathogenesis

Aberrant splicing and point mutations in the human presenilin genes, PSEN1 and PSEN2, have been linked to familial forms of Alzheimer's disease. We have previously described that low-level aberrant splicing of exon 8 in zebrafish psen1 transcripts in zebrafish embryos produces potent dominant negative effects that increase psen1 transcription, cause a dramatic hydrocephalus phenotype, decreased pigmentation and other developmental defects. Similar effects are also observed after low-level interference with splicing of exon 8 of psen2. To determine the molecular etiology of these effects, we performed microarray analyses of global gene expression changes. Of the 100 genes that showed greatest dysregulation after either psen1 or psen2 manipulation, 12 genes were common to both treatments. Five of these have known function and showed increased expression: cyclin G1 (ccng1), prosaposin (psap), cathepsin Lb (ctslb), heat shock protein 70kDa (hsp70) and hatching enzyme 1 (he1). We used phylogenetic and conserved synteny analysis to confirm the orthology of zebrafish ccng1 with human CCNG1. We analyzed the expression of zebrafish ccng1 in developing embryos to 24 hours post fertilization (hpf). Decreased ccng1 expression does not rescue the hydrocephalus or pigmentation phenotypes of embryos with aberrant splicing of psen1 exon 8.

Sorting of fine powder by gravitational classification chambers

Gravitational classification chambers (GCCs) were generally never used to classify fine powder because of its poor accuracy. However, in this study, a high quality closed-loop wind tunnel was designed and manufactured to improve this GCC drawback. A high quality closed-loop wind tunnel was designed to provide a low wall interference and low turbulence level in the test section. A wide-span feeder fed the powder smoothly as a curtain with a uniform aerodynamic interaction by the cross wind. The classification performance of GCCs has therefore been improved, and it could now classify lead–tin (Pb–Sn) powder with particle sizes smaller than 200 μm by controlling feeding rate and cross flow speed. Our experimental results show that GCCs have good classification performance from the view of the index of classification size ratio (CSR) by controlling cross flow speed and feeding rate. For GCCs the best sharpness index is about 0.4, the CSR is 1.09, and the cut size is 15.8 μm. The results demonstrate that GCCs had a fine powder classification capability and its cut-point was accurate enough for use in a classification operation. Furthermore, GCCs could be used to reduce ultra fine powder from raw powder. The volume percentage under 10 μm of raw material decreased from 7.61% to 0.64% through three repeatable classifications. This function could be considered as a good pre-process for specific classifiers (sieves or centrifugal classifiers). The product efficiency of this specific classifier could be increased by coupling it with GCCs.

Does Selection against Transcriptional Interference Shape Retroelement-Free Regions in Mammalian Genomes?

BackgroundEukaryotic genomes are scattered with retroelements that proliferate through retrotransposition. Although retroelements make up around 40 percent of the human genome, large regions are found to be completely devoid of retroelements. This has been hypothesised to be a result of genomic regions being intolerant to insertions of retroelements. The inadvertent transcriptional activity of retroelements may affect neighbouring genes, which in turn could be detrimental to an organism. We speculate that such retroelement transcription, or transcriptional interference, is a contributing factor in generating and maintaining retroelement-free regions in the human genome.Methodology/Principal FindingsBased on the known transcriptional properties of retroelements, we expect long interspersed elements (LINEs) to be able to display a high degree of transcriptional interference. In contrast, we expect short interspersed elements (SINEs) to display very low levels of transcriptional interference. We find that genomic regions devoid of long interspersed elements (LINEs) are enriched for protein-coding genes, but that this is not the case for regions devoid of short interspersed elements (SINEs). This is expected if genes are subject to selection against transcriptional interference. We do not find microRNAs to be associated with genomic regions devoid of either SINEs or LINEs. We further observe an increased relative activity of genes overlapping LINE-free regions during early embryogenesis, where activity of LINEs has been identified previously.Conclusions/SignificanceOur observations are consistent with the notion that selection against transcriptional interference has contributed to the maintenance and/or generation of retroelement-free regions in the human genome.

Evaluating the differential roles of the dorsal dentate gyrus, dorsal CA3, and dorsal CA1 during a temporal ordering for spatial locations task

It has been demonstrated that the dorsal CA1 subregion of the hippocampus mediates temporal processing of information, that dorsal CA3 participates in the spatiotemporal processing of memory, and the dorsal dentate gyrus (DG) mediates spatial pattern separation. A temporal ordering of spatial locations task was developed to test the role of the dorsal DG, CA3, and CA1 for the temporal processing of spatial information with either high or low levels of spatial interference. The results indicate that animals with DG lesions showed difficulty performing the task at high levels of spatial interference, but were able to perform the task well when there was low spatial interference. Animals with lesions to CA3 did not show a preference for either spatial location presented during the study phase during the preference test, suggesting impaired spatiotemporal processing. Animals with lesions to CA1 showed a preference for a later presented spatial location over the earlier, the opposite preference to that shown by control animals.

A novel gaseous pinacolyl alcohol sensor utilizing cataluminescence on alumina nanowires prepared by supercritical fluid drying

A cataluminescence (CTL) sensor using Al 2O 3 nanowires as the sensing material was developed for the determination of trace pinacolyl alcohol in air samples based on the catalytic chemiluminescence (CL) of pinacolyl alcohol on Al 2O 3 nanowires. Eight catalysts were examined and the CL intensity on Al 2O 3 nanowires prepared by supercritical fluid drying was the strongest. This novel CL sensor showed high sensitivity and selectivity to gaseous pinacolyl alcohol at optimal temperature of 340 °C. Quantitative analysis was performed at a wavelength of 460 nm. The linear range of CTL intensity versus concentration of gaseous pinacolyl alcohol was 0.09 × 10 −6 to 2.56 × 10 −6 g mL −1 ( r = 0.9983, n = 6) with a detection limit (3 σ) of 0.0053 × 10 −6 g mL −1. None or only very low levels of interference were observed while the foreign substances such as water vapor, ethanol, ammonia, chloroform, benzene, nitrogen dioxide, methylbenzene, hydrochloric acid, methanol and butanol were passing through the sensor. The response time of the sensor is less than 100 s, and the sensor had a long lifetime more than 60 h. The sensor would be potentially applied to analysis of the nerve agents such as Soman.

Cluster analysis and lower urinary tract symptoms in men: findings from the Boston Area Community Health Survey

To classify lower urinary tract symptoms (LUTS) in a large, representative sample of men in the USA by means of cluster analysis and to investigate risk factors and comorbidities associated with the resulting cluster patterns. A combination of hierarchical and non-hierarchical cluster methods was used to assign men with LUTS in the Boston Area Community Health (BACH) study to symptom-based categories or clusters. Of the 2301 men in the BACH study, those reporting one or more of 14 common LUTS (1592 men) were included in the analysis. The prevalence and frequency of symptoms in each cluster was assessed, in addition to the demographic, lifestyle risk factors, comorbidities, quality of life, and interference with activities of daily living associated with each cluster. We used anova methods for assessing cluster effects on continuous variables, and cross-classification and chi-square tests for categorical measures. Internal validity of the cluster solution was tested by means of a split-half replication, and external validity by comparison with previously published data. Five clusters were identified among symptomatic men. About half of the symptomatic men were assigned to Cluster 1, which included individuals with a low prevalence and frequency of urological symptoms and a correspondingly low level of interference with activities of daily living. There were intermediate levels of symptom frequency and prevalence in Clusters 2-4, which were characterized by mixed patterns of voiding, storage and postvoiding symptoms. Cluster 5 consisted of predominantly older men (mean age 58.9 years), with a high prevalence and frequency of urological symptoms with a mean (SD) number of symptoms of 9.9 (2.1), and with elevated levels of comorbid cardiovascular disease (P < 0.001). These men also had higher rates of kidney and bladder infections and previous urological surgery. Men with increased waist circumference and more sedentary lifestyles were over-represented in the more symptomatic clusters. Cluster analysis provides an empirically based method for categorizing men with LUTS. These findings provide a new framework for examining aetiological pathways and mechanisms, the potential impact of and consequences for comorbid conditions, and for assessing prognosis and outcomes associated with common urological disorders.

Test Method for Measuring Bit Error Rate of Pulsed Transceivers in Presence of Narrowband Interferers

The popularity of pulse-based transceivers can be attributed to the high information rates that can be achieved in such systems compared to traditional narrowband systems. However, such systems are usually low-power and transmission efficiency is severely affected by the interference signals from other moderate to high-power narrowband transmitters. Hence, during manufacturing, pulse-based systems must be characterized and tested for bit error rate (BER) performance in the presence of narrowband interferers. Usually, at large interference levels, the BER is moderate (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> ) to high (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ). However, at low interference levels when very few bits are in error, the BER is low (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> - 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-10</sup> ) and testing for the BER becomes time consuming. We propose a new measurement technique employing sinusoidal pulses such that the BER value obtained is significantly large (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> - 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> ) even at low interference levels. BER values obtained using sinusoidal pulses are highly correlated to the actual BER values. Hence, the actual BER can be accurately estimated in a much smaller time without actually performing the standard test. This method was implemented in hardware using an Altera field-programmable gate-array development board. From the measurements, BER estimation error was less than 3%. In addition, significant reduction (up to 100 x) in test time was obtained using the proposed method.

An enhanced biosensor for glutamate based on self-assembled carbon nanotubes and dendrimer-encapsulated platinum nanobiocomposites-doped polypyrrole film

An enhanced amperometric biosensor based on incorporating one kind of unique nanobiocomposite as dopant within an electropolymerized polypyrrole film has been investigated. The nanobiocomposite was synthesized by self-assembling glutamate dehydrogenase (GLDH) and poly(amidoamine) dendrimer-encapsulated platinum nanoparticles (Pt-DENs) onto multiwall carbon nanotubes (CNTs). ζ-Potentials and high-resolution transmission electron microscopy (HRTEM) confirmed the uniform growth of the layer-by-layer nanostructures onto the carboxyl-functionalized CNTs. The size of Pt nanoparticles is approximately 3 nm. The (GLDH/Pt-DENs) n /CNTs/Ppy hybrid film was obtained by electropolymerization of pyrrole onto glassy carbon electrodes and characterized with scanning electron microscopy (SEM), cyclic voltammetry (CV) and other electrochemical measurements. All methods indicated that the (GLDH/Pt-DENs) n /CNTs nanobiocomposites were entrapped within the porous polypyrrole film and resulted in a hybrid film that showed a high electrocatalytic ability toward the oxidation of glutamate at a potential 0.2 V versus Ag/AgCl. The biosensor shows performance characteristics with high sensitivity (51.48 μA mM −1), rapid response (within 3 s), low detection limit (about 10 nM), low level of interference and excellent reproducibility and stability.

High resolution channel sounder with narrowband low interference characteristics

Channel impulse response (CIR) measurements typically require the transmission of high power wideband probing signals to characterise channels. These signals are potentially harmful to users of the spectrum under assessment This paper presents a method of high resolution channel sounding causing only low levels of wideband interference and details a measurement system developed to characterise the band currently used for global navigation satellite systems (GNSS), where high levels of probing signal would have safety of life implications.

RFI detection and mitigation for microwave radiometry with an agile digital detector

A new type of microwave radiometer detector has been developed that is capable of identifying high and low levels of radio-frequency interference (RFI) and of reducing or eliminating its effect on the measured brightness temperatures. High-level, localized RFI can be easily identified by its unnatural appearance in brightness temperature imagery. Low-level or persistent RFI can be much more difficult to identify and filter out. The agile digital detector (ADD) can discriminate between RFI and natural thermal emission signals by directly measuring higher order moments of the signal than the variance that is traditionally measured. After detection, the ADD then uses spectral filtering methods to selectively remove the RFI. ADD performance is experimentally verified in controlled laboratory tests and in the field near a commercial air traffic control radar. High-level RFI is easily identified and removed. Very low level RFI contamination, with power levels as low as the radiometric measurement uncertainty of the radiometer, is also shown to be reliably detected and removed.

Production test technique for measuring BER of ultra-wideband (UWB) devices

Ultra-wideband is an emerging standard for short-range high data-rate wireless communication. In a production test environment, ultra-wideband devices are tested for bit error rate (BER) in the presence of an external interferer. As the target BER values are small at low interference levels, it requires a long test sequence for measuring BER, incurring a long test time. This paper describes a novel production test technique for BER testing of orthogonal frequency-division multiplexing transceivers. By adjusting the phase values of the baseband signal, the proposed manufacturing test methodology reduces the overall test time considerably (up to 20/spl times/), while keeping the error vector magnitude and peak-to-average ratio of the transmitted signal unchanged. This method can be extended to any phase modulation scheme to reduce the test time for BER.

Cortical Bone Viscoelasticity and Fixation Strength of Press-Fit Femoral Stems: An In-Vitro Model

Cementless total hip femoral components rely on press-fit for initial stability and bone healing and remodeling for secondary fixation. However, the determinants of satisfactory press-fit are not well understood. In previous studies, human cortical bone loaded circumferentially to simulate press-fit exhibited viscoelastic, or time dependent, behavior. The effect of bone viscoelastic behavior on the initial stability of press-fit stems is not known. Therefore, in the current study, push-out loads of cylindrical stems press-fit into reamed cadaver diaphyseal femoral specimens were measured immediately after assembly and 24 h with stem-bone diametral interference and stem surface treatment as independent variables. It was hypothesized that stem-bone interference would result in a viscoelastic response of bone that would decrease push-out load thereby impairing initial press-fit stability. Results showed that push-out load significantly decreased over a 24 h period due to bone viscoelasticity. It was also found that high and low push-out loads occurred at relatively small amounts of stem-bone interference, but a relationship between stem-bone interference and push-out load could not be determined due to variability among specimens. On the basis of this model, it was concluded that press-fit fixation can occur at relatively low levels of diametral interference and that stem-bone interference elicits viscoelastic response that reduces stem stability over time. From a clinical perspective, these results suggest that there could be large variations in initial press-fit fixation among patients.