An experimental investigation of the phenomenon of auditory fatigue

Auditory fatigue is now known as Temporary Threshold Shift (subsequently abbreviated to TTS). It has been defined as the temporary elevation in the absolute threshold of hearing for a given test sound resulting from preceding auditory stimulation by a given stimulus sound (see Hirsh, 1952, page 177). Associated with the phenomenon there are six physical variables which sub-divide themselves into stimulus, test and recovery factors. In IMS study each of the latter factors was systematically Investigated using four groups of six undergraduate subjects. Thresholds were measured using the Bek6sy (1947) technique of threshold measurement. Control experiments were carried out to verify that TTS results from the application of the stimulus tone, to study the mechanisms involved in the Bekesy technique of threshold measurement and the effects of this technique on the measurement of TTS, to investigate any additive effects of TTS and to study the possibility of any measurement errors resulting from the physical test environment. The results of the experiments showed that the stimulus test and recovery factors all produced a consistent duality of results. It was concluded that the unitary definition of TTS is inadequate and that there are two TTS mechanisms. These are referred to as fatigue and temporal stimulation deafness. Fatigue is associated with moderately intense stimulus tones of fairly short duration. It increases linearly with logarithm of the stimulus duration; it is maximal at stimulus frequencies of 1000, 2000 and 3000 cps; it does not vary significantly with stimulus intensities of up to 90 db. but thence increases rapidly to a maximum; it is maximal at a test frequency equal to the stimulus frequency and recovery from it is complete within one minute of the cessation of the stimulus. Temporary stimulation deafness is associated with high intensity stimulus tones of fairly long duration. It increases linearly with the logarithm of the stimulus duration; it is maximal with stimulus frequencies of 4000 to 6000 cps; it increases rapidly as the stimulus intensity is increased; it is maximal at a test frequency an octave above the stimulus frequency and recovery from it takes longer than one minute from the cessation of the stimulus tone. It is hypothesized that fatigue is a neural, possibly bio-chemical, adaptation effect and that temporary stimulation deafness results from structural damage to the organ of Corti. Other work supports this differentiation. The phenomena of fatigue support either a "place" or a "volley" theory of hearing. The phenomena of temporary stimulation deafness are partially explicable in terms of the anatomical characteristics of the ear

Experiments on Chemical Control of Behavior in Brown Tree Snakes

The brown tree snake (Boiga irregularis), accidentally introduced on Guam shortly after World War 11, is the target of extensive efforts aimed at reducing populations and preventing their spread to other Pacific islands. Chemical attractants and repellents have been investigated, and this paper presents an overview of current knowledge. In particular, chemical cues that have strong effects in laboratory tests have had only modest (though significant) effects in field tests on Guam. Reasons for the different outcomes of laboratory and field studies are discussed along with recommendations for the redesign of laboratory experiments

How and when of eyelid reconstruction using autologous transplantation

Reconstructive surgery of the eyelid after tumor excision, trauma or other causes can be challenging, especially due to the complexities of the anatomic structures and to the necessity of both functional and aesthetic successful outcomes. The aim of this minireview was to investigate the use of tissue transplantation in eyelid reconstruction. Surgical procedures are various, based on the use of both flaps, pedicled or free, and grafts, in order to guarantee adequate tissue reconstruction and blood supply, which are necessary for correct healing. Common techniques normally include the use of local tissues, combining non-vascularized grafts with a vascularized flap for the two lamellae repair, to attempt a reconstruction similar to the original anatomy. When defects are too wide, vast, deep, and complex or when no adjacent healthy tissues are available, distant area tissues need to be recruited as free flaps or grafts and paired with mucosal layer reconstruction. With regards to the anterior lamella, full thickness skin grafts are commonly preferred. With regards to the reconstruction of posterior lamella, there are different graft options, which include conjunctival or tarsoconjunctival, mucosal or palatal or cartilaginous grafts usually combined with local flaps. Free flap transplantation, normally reserved for rare select cases, include the use of the radial forearm and anterolateral flaps combined with mucosal grafts, which are surgical options currently reported in the literature

Surface grafting of electrospun fibers using ATRP and RAFT for the control of biointerfacial interactions

BACKGROUND The ability to present signalling molecules within a low fouling 3D environment that mimics the extracellular matrix is an important goal for a range of biomedical applications, both in vitro and in vivo. Cell responses can be triggered by non-specific protein interactions occurring on the surface of a biomaterial, which is an undesirable process when studying specific receptor-ligand interactions. It is therefore useful to present specific ligands of interest to cell surface receptors in a 3D environment that minimizes non-specific interactions with biomolecules, such as proteins. METHOD In this study, surface-initiated atom transfer radical polymerization (SI-ATRP) of poly(ethylene glycol)-based monomers was carried out from the surface of electrospun fibers composed of a styrene/vinylbenzyl chloride copolymer. Surface initiated radical addition-fragmentation chain transfer (SI-RAFT) polymerisation was also carried out to generate bottle brush copolymer coatings consisting of poly(acrylic acid) and poly(acrylamide). These were grown from surface trithiocarbonate groups generated from the chloromethyl styrene moieties existing in the original synthesised polymer. XPS was used to characterise the surface composition of the fibers after grafting and after coupling with fluorine functional XPS labels. RESULTS Bottle brush type coatings were able to be produced by ATRP which consisted of poly(ethylene glycol) methacrylate and a terminal alkyne-functionalised monomer. The ATRP coatings showed reduced non-specific protein adsorption, as a result of effective PEG incorporation and pendant alkynes groups existing as part of the brushes allowed for further conjugation of via azide-alkyne Huisgen 1,3-dipolar cycloaddition. In the case of RAFT, carboxylic acid moieties were effectively coupled to an amine label via amide bond formation. In each case XPS analysis demonstrated that covalent immobilisation had effectively taken place. CONCLUSION Overall, the studies presented an effective platform for the preparation of 3D scaffolds which contain effective conjugation sites for attachment of specific bioactive signals of interest, as well as actively reducing non-specific protein interactions.This research was supported by the Cooperative Research Centre for Polymers (CRCP)

Impact of COVID-19 pandemic on ophthalmic presentations to an Australian outer metropolitan and rural emergency department: a retrospective comparative study.

BACKGROUND: To analyse ophthalmic presentations to an outer metropolitan and a rural emergency department (ED) during the first wave of the COVID-19 pandemic in New South Wales (NSW), Australia. METHODS: A retrospective comparative study of ophthalmic emergency presentations to Campbelltown Hospital (fifth busiest NSW metropolitan ED; population 310,000) and Bowral and District Hospital (rural ED; population 48,000) before and during COVID-19 was conducted. Patient demographics, triage category, referral source, diagnosis, length of stay, departure status, and follow-up location were assessed from coding data between March 1st to May 31st in 2019 and 2020, corresponding to the peak case numbers and restrictions during the first wave of the COVID-19 pandemic in NSW. Differences before and during COVID-19 were analysed using chi-squared tests or independent sample t-tests. RESULTS: There was no change in ophthalmic presentations at Campbelltown (n = 228 in 2019 vs. n = 232 in 2020; + 1.75%, p = 0.12) and an increase at Bowral (n = 100 in 2019 vs. n = 111 in 2020; + 11%, p < 0.01) during COVID-19. Urgent ophthalmic presentations (Triage Category 3) decreased at Bowral (p = 0.0075), while non-urgent ophthalmic presentations (Triage Category 5) increased at both hospitals (Campbelltown p < 0.05, Bowral p < 0.01). CONCLUSIONS: There was no change in the total number of ophthalmic presentations to an outer metropolitan and an increase to a rural ED during the first wave of the COVID-19 pandemic in New South Wales, Australia. A change in the type of ophthalmic presentations at these peripheral EDs suggest that a high demand for ophthalmic services remained despite the pandemic and its associated gathering and movement restrictions. A flexible healthcare delivery strategy, such as tele-ophthalmology, may optimise patient care during and after COVID-19

Jet stream variability in a polar warming scenario – a laboratory perspective

We report on a set of laboratory experiments to investigate the effect of polar warming on the mid-latitude jet stream. Our results show that a progressive decrease in the meridional temperature difference slows down the eastward propagation of the jet stream and complexifies its structure. Temperature variability decreases in relation to the laboratory “Arctic warming” only at locations representing the Earth's polar and mid-latitudes, which are influenced by the jet stream, whilst such a trend is reversed in the subtropical region south of the simulated jet. The reduced variability results in narrower temperature distributions and hence milder extreme events. However, our experiments also show that the frequency of such events increases at polar and mid-latitudes with decreased meridional temperature difference, whilst it decreases towards the subtropics. Despite missing land–sea contrast in the laboratory model, we find qualitatively similar trends of temperature variability and extreme events in the experimental data and the National Centers for Environmental Prediction (NCEP) reanalysis data

Water security in South Africa: perceptions on public expectations and municipal obligations, governance and water re-use

South Africa is a water-scarce country with increasing pressure on its water resources. Urgent interventions are needed to protect water security within this rapidly developing country. This paper reports on an interdisciplinary Water Security Colloquium, convened by the South African Young Academy of Science in 2014. A selected group of water professionals from academia, civil society and local government was brought together to discuss water security under three focus themes: ‘public expectations and municipal obligations’, ‘water security and governance: challenges and advances’, and ‘water re-use: health and infrastructural considerations’. Participant perceptions were generated using a focus group methodology, combined with participatory data collection methods. Under each theme, inputs were categorised as ‘challenges’, ‘gaps in knowledge’, and ‘solutions/recommendations’ and these inputs were thereafter ranked in order of importance via a ‘voting’ process. Major challenges perceived included a lack of both skills and political will in government, a need to restore citizen trust in government intention and capability to deliver water-related services, and a failure to up-scale existing water re-use technology. Participants identified understanding of the process and implications of the Green and Blue Drop Programmes, knowledge transfer to the public, and the role of educators as major knowledge gaps. The top suggestions proposed included creating public awareness around and buy-in to initiatives to improve water security, accessible and user-friendly conversion of research results to implementation, and ensuring an active role for educators in creating awareness around water security. In view of the concerns identified, participants suggested as potential solutions: improving government and public understanding around water issues, incentivising water re-use and conservation, introducing rising block tariffs and improving human capacity development in the water sector. Developing the ecological infrastructure that protects both quantity and quality of water and building strong partnerships among all stakeholders were also recognised as key.Keywords: capacity development, education, governance, water security, water re-use, water conservation, local governmen

GAMBLINGLESS: FOR LIFE study protocol: a pragmatic randomised trial of an online cognitive–behavioural programme for disordered gambling

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0