A frequency-selective feedback model of auditory efferent suppression and its implications for the recognition of speech in noise

The potential contribution of the peripheral auditory efferent system to our understanding of speech in a background of competing noise was studied using a computer model of the auditory periphery and assessed using an automatic speech recognition system. A previous study had shown that a fixed efferent attenuation applied to all channels of a multi-channel model could improve the recognition of connected digit triplets in noise [G. J. Brown, R. T. Ferry, and R. Meddis, J. Acoust. Soc. Am. 127, 943?954 (2010)]. In the current study an anatomically justified feedback loop was used to automatically regulate separate attenuation values for each auditory channel. This arrangement resulted in a further enhancement of speech recognition over fixed-attenuation conditions. Comparisons between multi-talker babble and pink noise interference conditions suggest that the benefit originates from the model?s ability to modify the amount of suppression in each channel separately according to the spectral shape of the interfering sounds

A catchment-based study of endocrine disruption in surface waters: multivariate evaluation of the health of a sentinel fish species exposed to sewage treatment works effluent

Summary of the results in the context of EDCAT 5 project aims: 1. By comparing appropriate biomarkers in fish sampled from STW-impacted sites and control sites during the pre-remediation period, to determine whether there was evidence for any effects that might be attributed to the presence of estrogenic (or androgenic, or anti-androgenic/-estrogenic) endocrine disrupting chemicals in the former. This aim was addressed by measuring concentrations of the estrogen-dependent yolk protein precursor vitellogenin, and the androgen-dependent nest glue spiggin in male and female sticklebacks. In addition histological examination of the gonadal structure of fish captured at the impacted and non-impacted sites was employed to seek evidence of overt alterations in reproductive physiology of the fish. For a subset of matched samples from the two rivers, the relative induction of hepatic choriogenin mRNA, a biomarker of estrogen exposure, was measured. Conclusions: Chemistry data provided by EDCAT3&4 showed that estrogenicity of the effluent was low prior to remediation and lower still following installation of the GAC plant. No evidence of overt estrogenic effects was detected in male sticklebacks in the Ray, VTG and ChG levels were similar in males from both rivers. Nor was there any evidence of alterations in spiggin concentrations in the kidneys of males from the Ray compared to the Ock. However, VTG concentrations in female sticklebacks from the Ray were increased following the STW upgrade as were hepatic ChG transcript levels, and kidney spiggin concentrations. No changes in these elements of the reproductive system were observed in females from the Ock across the same time periods. Chemical analysis of the effluent indicated that prior to installation of the GAC plant substantial concentrations of anti-androgenic chemicals were present, together with a wide range of other organics. Concentrations of these were much reduced following the plant upgrade. It is reasonable to suppose that the changes observed in the female reproductive endocrine system following the upgrade were related to the removal of some or all of this complex mixture of chemicals. The absence of effects in males may be related to the balance between exogenous and endogenous signals, or to the specificity of effects exerted by the chemicals present. No intersex fish were detected from either river. A significant bias in favour of females was detected in the stickleback populations in both rivers suggesting a factor associated with life-history of the fish, rather than contaminant burden, was responsible. 2. By comparing appropriate biomarkers in fish sampled from STW-impacted sites and control sites during the pre-remediation period, to determine whether there was evidence for any effects that might be attributed to the presence of “conventionally” toxic chemicals. This was addressed by measurement of the activity of a key Phase I transforming enzyme in the liver of fish, either using direct enzymatic assay (EROD) or by quantifying the levels of expression of the corresponding gene (CYP1A). Conclusions: EROD activity was significantly greater in fish from the Ray than the Ock in two samples collected prior to the installation of the GAC plant (2006, 2007) and this likely reflects the differential contaminant loading in the two rivers. A single sample following the commissioning of the GAC plant (2008) indicated that EROD activity had increased among fish from the Ock while that in fish from the Ray remained unchanged. While a delayed recovery of this biomarker in fish from the Ray may be expected depending on the route of exposure (direct via water or indirect via contaminated food) the reasons for elevated EROD activity in fish from the Ock/Childrey Brook are not immediately evident. Provision of a full data set for Cyp1A expression awaits the repeat of the assay. When this is complete the factors underlying the EROD findings may become clear. 3. To determine whether the adaptive capacity and energetic status of fish varied between the STW-impacted and non-impacted sites. This was addressed by measurement of indicators of stress (whole-body corticosteroid levels), metabolic status (whole-body glucose levels) and anabolic activity (RNA:DNA ratios). Conclusions: The data provide no evidence that the stress response of fish captured in the Ray prior to installation of the GAC plant was modified by exposure to the effluent. However, large variations in whole-body corticosteroid and glucose concentrations in fish from both rivers, with clear trends over time, were closely linked to perturbations in the river flow regime. Whether there was interaction between environmental and chemical factors in determining corticosteroid and glucose status is difficult to discern but it seems likely that variation in these indicators of the stress axis was driven primarily by environmental factors. The RNA:DNA ratios were closely linked with seasonal change in temperature and closely matched observed patterns of weight and length gain in stickleback populations in the two rivers. The longer growth period enjoyed by fish in the Ray was clearly evident. For both rivers, mean anabolic activity was greater during 2008 than 2007 and it seems likely that this is related to adverse effects associated with the periods of extreme flow change observed on both rivers in 2007. 4. To assess whether there were differences in population size and structure between STW-impacted and non-impacted sites. This was addressed by comparison of key somatic measures, in particular frequency distributions for fork length. Conclusions: Because of the extreme patchiness of the distribution of stickleback populations in both rivers accurate abundance estimates were not obtained. However, the catch per unit effort across the life of the project was similar for both rivers. While population size, and age structure (both rivers hosted annual populations), appeared to be similar fish in the Ray were overall larger than those from the Ock, and spawned earlier. The differences in growth and timing of spawning between the rivers were likely to have been associated with the Rodbourne STW effluent. Downstream of the discharge on the Ray water temperatures were consistently 2 – 3oC above those of the Ock. This temperature difference, in combination with the introduction of additional nutrients into the river which is likely to have affected the availaibility of food, probably accounts for the different growth profile among the sticklebacks in the two rivers. However, over and above this difference, there was a significant increase in size of sticklebacks in the Ray between the matched pre- and post-remediation periods in the Ray while no change in size of the fish in the Ock occurred during the same period. Similarly, the RNA:DNA ratio was higher in fish from the Ock during 2007 but greater in fish from the Ray during 2008. Taken together, these observations suggest that there was an improvement in the status of the fish in the Ray following the commissioning of the GAC plant, while the population in the Ock remained relatively stable. It is reasonable to suppose that this may be linked to the reduction of the chemical load entering the Ray at Rodbourne following the installation of the GAC plant. The Ray is “cleaner” now than was the case prior to remediation but remains nutrient rich and several degrees warmer than the Ock, this combination of factors providing fish in the Ray with greater scope for growth relative to populations in the Ock

The representation of speech in a nonlinear auditory model: time-domain analysis of simulated auditory-nerve firing patterns

A nonlinear auditory model is appraised in terms of its ability to encode speech formant frequencies in the fine time structure of its output. It is demonstrated that groups of model auditory nerve (AN) fibres with similar interpeak intervals accurately encode the resonances of synthetic three-formant syllables, in close agreement with physiological data. Acoustic features are derived from the interpeak intervals and used as the input to a hidden Markov model-based automatic speech recognition system. In a digits-in-noise recognition task, interval-based features gave a better performance than features based on AN firing rate at every signal-to-noise ratio tested

Exploration of Cardiology Patient Hospital Presentations, Health Care Utilisation and Cardiovascular Risk Factors During the COVID-19 Pandemic

Objectives: COVID-19 and the lockdowns have affected health care provision internationally, including medical procedures and methods of consultation. We aimed to assess the impact of COVID-19 at two Australian hospitals, focussing on cardiovascular hospital admissions, the use of community resources and cardiovascular risk factor control through a mixed methods approach. Methods: Admissions data from the quaternary referral hospital were analysed, and 299 patients were interviewed from July 2020 to December 2021. With the admissions data, the number, complexity and mortality of cardiology hospital admissions, prior to the first COVID-19 lockdown (T0=February 2018–July 2019) were compared to after the introduction of COVID-19 lockdowns (T1=February 2020–July 2021). During interviews, we asked patients about hospital and community health resource use, and their control of cardiovascular risk factors from the first lockdown. Results: Admission data showed a reduction in hospital presentations (T0=138,099 vs T1=128,030) and cardiology admissions after the lockdown period began (T0=4,951 vs T1=4,390). After the COVID-19-related lockdowns began, there was an increased complexity of cardiology admissions (T0=18.7%, 95% CI 17.7%–19.9% vs T1=20.3%, 95% CI 19.1%–21.5%, chi-square test: 4,158.658, p<0.001) and in-hospital mortality (T0=2.3% of total cardiology admissions 95% CI 1.9%–2.8% vs T1=2.8%, 95% CI 2.3%–3.3%, chi-square test: 4,060.217, p<0.001). In addition, 27% of patients delayed presentation due to fears of COVID-19 while several patients reported reducing their general practitioner or pathology/imaging appointments (27% and 11% respectively). Overall, 19% reported more difficulty accessing medical care during the lockdown periods. Patients described changes in their cardiovascular risk factors, including 25% reporting reductions in physical activity. Conclusion: We found a decrease in hospital presentations but with increased complexity after the introduction of COVID-19 lockdowns. Patients reported being fearful about presenting to hospital and experiencing difficulty in accessing community health services

The influence of exposure and physiology on microplastic ingestion by the freshwater fish Rutilus rutilus (roach) in the River Thames, UK

Microplastics are widespread throughout aquatic environments. However, there is currently insufficient understanding of the factors influencing ingestion of microplastics by organisms, especially higher predators such as fish. In this study we link ingestion of microplastics by the roach Rutilus rutilus, within the non-tidal part of the River Thames, to exposure and physiological factors. Microplastics were found within the gut contents of roach from six out of seven sampling sites. Of sampled fish, 33% contained at least one microplastic particle. The majority of particles were fibres (75%), with fragments and films also seen (22.7% and 2.3% respectively). Polymers identified were polyethylene, polypropylene and polyester, in addition to a synthetic dye. The maximum number of ingested microplastic particles for individual fish was strongly correlated to exposure (based on distance from the source of the river). Additionally, at a given exposure, the size of fish correlated with the actual quantity of microplastics in the gut. Larger (mainly female) fish were more likely to ingest the maximum possible number of particles than smaller (mainly male) fish. This study is the first to show microplastic ingestion within freshwater fish in the UK and provides valuable new evidence of the factors influencing ingestion that can be used to inform future studies on exposure and hazard of microplastics to fish

Incidence and predictors of left ventricular thrombus formation following acute ST-segment elevation myocardial infarction: A serial cardiac MRI study

Aims: Left ventricular (LV) thrombus is a complication of acute ST-segment elevation myocardial infarction (STEMI). We determined the incidence and predictors of LV thrombus formation using serial cardiac magnetic resonance (CMR) and two-dimensional echocardiography studies. Methods and results: Two hundred and ten patients underwent CMR (median 4 days [IQR 3-7]) and transthoracic echocardiography (median 4 days [IQR 3-7]) early after STEMI presentation with serial follow-up CMR (median 55 days [IQR 46-64]) and echocardiography studies (median 54 days [IQR 45-64]) performed subsequently. The incidence of LV thrombus was 12.3% (26/210) by CMR and 6.2% (13/210) by two-dimensional echocardiography. Echocardiography had 50% sensitivity and 100% specificity for LV thrombus detection compared to CMR. LV thrombus was found in 23.6% of patients with anterior STEMI (22/93). Ischaemic stroke occurred in 1.4% of patients (3/210). Patients with LV thrombus had lower baseline LV ejection fraction (LVEF) (34.9% vs 47.4%, p < 0.001). Microvascular obstruction was more common in patients with LV thrombus (77% vs 39%, p < 0.001). Patients with LV thrombus had increased LV dimensions with larger LV end-diastolic (19 ml [IQR 9-44] vs 6 ml [IQR -4-18], p < 0.001) and end-systolic volumes (10 ml [IQR 0–22] vs -4 ml [IQR -12-4], p < 0.001). Conclusion: CMR increases the detection of LV thrombi which standard echocardiography may underestimate. Serial studies post-STEMI may improve detection of LV thrombus, which is more prevalent in patients with anterior infarction, moderate LV dysfunction and adverse LV remodelling. This subgroup of patients may represent a high-risk group for targeted serial screening with CMR

Fate and transport of polychlorinated biphenyls (PCBs) in the River Thames catchment – insights from a coupled multimedia fate and hydrobiogeochemical transport model

The fate of persistent organic pollutants (POPs) in riverine environments is strongly influenced by hydrology (including flooding) and fluxes of sediments and organic carbon. Coupling multimedia fate models (MMFMs) and hydrobiogeochemical transport models offers unique opportunities for understanding the environmental behaviour of POPs. While MMFMs are widely used for simulating the fate and transport of legacy and emerging pollutants, they use greatly simplified representations of climate, hydrology and biogeochemical processes. Using additional information about weather, river flows and water chemistry in hydrobiogeochemical transport models can lead to new insights about POP behaviour in rivers. As most riverine POPs are associated with suspended sediments (SS) or dissolved organic carbon (DOC), coupled models simulating SS and DOC can provide additional insights about POPs behaviour. Coupled simulations of river flow, DOC, SS and POP dynamics offer the possibility of improved predictions of contaminant fate and fluxes by leveraging the additional information in routine water quality time series. Here, we present an application of a daily time step dynamic coupled multimedia fate and hydrobiogeochemical transport model (The Integrated Catchment (INCA) Contaminants model) to simulate the behaviour of selected PCB congeners in the River Thames (UK). This is a follow-up to an earlier study where a Level III fugacity model was used to simulate PCB behaviour in the Thames. While coupled models are more complex to apply, we show that they can lead to much better representation of POPs dynamics. The present study shows the importance of accurate sediment and organic carbon simulations to successfully predict riverine PCB transport. Furthermore, it demonstrates the important impact of short-term weather variation on PCB movement through the environment. Specifically, it shows the consequences of the severe flooding, which occurred in early 2014 on sediment PCB concentrations in the River Thames