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While a comprehensive booth audiogram is the gold standard for diagnosis of hearing loss, access to this may not be available in remote and low resource settings. The aims of this study were to validate a tablet-based audiometer in a tertiary medical center in India and explore its capacity in improving access to hearing healthcare. Subjects presenting to Ear–Nose–Throat clinics for conventional booth audiometry testing were recruited for subsequent tablet-based audiometric testing. Testing with the tablet was conducted in a non-sound-treated hospital clinic room. Bilateral air and bone conduction hearing threshold data from 250 through 4000 Hz were validated against conventional booth audiometry. In addition, a small feasibility study was conducted in rural clinics. 70 participants (37 adults and 33 children between the ages 5–18) were assessed. 69% were male, with a mean age of 29.7 years. Sensitivity and specificity for the tablet were 89% (95% CI 80–94%) and 70% (95% CI 56–82%), respectively. While median differences in air conduction thresholds between conventional and tablet audiograms showed statistical significance at 250, 500, and 1000 Hz (p < 0.001), the threshold results of the tablet audiometer were within 5 dB of the conventional audiogram and not clinically significant. Ten patients were successfully screened in rural clinics with tablet audiometry. Tablet portable audiometry is a valid tool for air and bone conduction threshold assessment outside of conventional sound booths. It can accurately identify hearing impairment and offers a screening tool for hearing loss in low resource settings. [ABSTRACT FROM AUTHOR]

This work presents a Generalized Born model for the computation of the electrostatic component of solvation energies which is based on volume integration. An analytic masking function is introduced to remove Coulombic singularities. This approach leads to analytic formulae for the computation of Born radii, which are differentiable to arbitrary order, and computationally straightforward to implement. [ABSTRACT FROM AUTHOR]

The Elekta Synergy is a radiotherapy treatment machine with integrated kilovoltage (kV) X-ray imaging system capable of producing cone beam CT (CBCT) images of the patient in the treatment position. The aim of this study is to assess the additional imaging dose. Cone beam CT dose index (CBDI) is introduced and measured inside standard CTDI phantoms for several sites (head: 100 kV, 38 mAs, lung: 120 kV, 152 mAs and pelvis: 130 kV, 456 mAs). The measured weighted doses were compared with thermoluminescent dosimeter (TLD) measurements at various locations in a Rando phantom and at patients' surfaces. The measured CBDIs in-air at the isocentre were 9.2 mGy 100 mAs(-1), 7.3 mGy 100 mAs(-1) and 5.3 mGy 100 mAs(-1) for 130 kV, 120 kV and 100 kV, respectively. The body phantom weighted CBDI were 5.5 mGy 100 mAs(-1) and 3.8 mGy 100 mAs(-1 )for 130 kV and 120 kV. The head phantom weighted CBDI was 4.3 mGy 100 mAs(-1) for 100 kV. The weighted doses for the Christie Hospital CBCT imaging techniques were 1.6 mGy, 6 mGy and 22 mGy for the head, lung and pelvis. The measured CBDIs were used to estimate the total effective dose for the Synergy system using the ImPACT CT Patient Dosimetry Calculator. Measured CBCT doses using the Christie Hospital protocols are low for head and lung scans whether compared with electronic portal imaging (EPI), commonly used for treatment verification, or single and multiple slice CT. For the pelvis, doses are similar to EPI but higher than CT. Repeated use of CBCT for treatment verification is likely and hence the total patient dose needs to be carefully considered. It is important to consider further development of low dose CBCT techniques to keep additional doses as low as reasonably practicable. [ABSTRACT FROM AUTHOR]

Background: Between 1 and 2 per cent of head and neck squamous cell carcinoma patients will reveal no evidence of a primary malignancy. The management of this group poses many problems, including the morbidity associated with wide field irradiation as well as the difficulty in treatment when a primary does emerge. The aim of this study was to assess the use of fluoro-deoxy-glucose positron emission tomography (FDG-PET) imaging in patients presenting with an unknown head and neck primary and to consider its routine use in such patients.Methods: We enrolled 25 patients into our study over a four year period. They all presented with a histologically proven, metastatic, squamous cell carcinoma of the neck for which no primary could be found despite full clinical, endoscopic and radiological evaluation with computed tomography (CT) and/or magnetic resonance imaging (MRI). Additionally, all the patients underwent imaging using FDG-PET. The images were interpreted by two radiologists experienced in PET imaging.Results: A primary was identified in nine of the 25 patients (42 per cent); however, of these patients, six had false positive results and only three patients were true positives with supportive histology. In the remaining 16 patients, no abnormality was identified on CT, MRI or PET. Of these 16 patients, two eventually displayed a primary carcinoma, the other 14 patients remaining without evidence of any primary.Conclusion: Despite the high number of positive PET scans, the actual true positive rate was 3/9 (33 per cent); conversely, the true negative rate was 14/16 (88 per cent). We conclude from this study that there is a role for FDG-PET in the patient with an unknown head and neck primary, particularly in the context of a negative PET scan. [ABSTRACT FROM AUTHOR]

The environmental scanning electron microscope (ESEM) allows the sample to be imaged under a low pressure atmosphere. The ability to micromanipulate with precision within heated power systems in an ESEM will enable a greater understanding of the behaviour of materials at high temperature. Heating stages for ESEMs are commercially available but none include micromanipulation systems. Creating such a system is fraught with design problems. This is because the piezoelectric transducers, required to generate the precise range of movement within the heated environment, are unable to operate at temperatures exceeding about 90 °C and require thermal protection. Here, we have used a one-dimensional probe as a model of a three-dimensional manipulator. We have introduced a thermal break and a thermally insulating extension arm to protect the piezoelectric from heat. We have applied finite element analysis to test the design concepts before practical implementation. This ensures that the piezoelectric transducers in the costly practical devices are not placed at risk. The predictions have been validated with subsequent experimental work although there are some discrepancies to resolve. Examples of the movement of aluminium alloy grains and copper powder particles using the one-dimensional manipulator are given. [ABSTRACT FROM AUTHOR]

Verification of target organ position is essential for the accurate delivery of conformal radiotherapy. Megavoltage electronic portal imaging with flat panel amorphous silicon detectors delivers high quality images that can be used for verification of bony landmark position. Gold markers implanted into the target organ can be visualized and used as a surrogate of actual organ position. On-line compensation for marker displacement, by adjusting patient position, can reduce geometric errors associated with radiation delivery. This study assesses the optimal marker length and diameter to be used with an amorphous silicon (a-Si) flat panel detector and electronic portal images (EPIs), prior to implementation of a clinical programme of gold marker insertion in prostate cancer patients. Seven marker sizes varying from 3 mm to 8 mm in length and 0.8 mm to 1.1 mm in diameter were investigated in a group of patients undergoing pelvic radiotherapy using an 8 MV Elekta SL20 linear accelerator. Markers were placed on the skin entry and exit sites of the treatment beam and EPIs in both lateral and anterior pelvic views were acquired. Three observers independently assessed visibility success and failure using a subjective scoring system. Markers less than 5 mm in length or 0.9 mm in diameter were poorly visualized (<70% visualization success in lateral EPIs). The marker measuring 0.9 mm x 5 mm appears to be clinically optimal in pelvic radiotherapy patients (80% visualization success in lateral EPIs) and will be used for actual organ implantation. [ABSTRACT FROM AUTHOR]

: Background and Aims Although the causes and consequences of seedling herbivory for plant community composition are well understood, the mechanisms by which herbivores influence plant species recruitment to the established phase remain less clear. The aim was to examine how variation in the intensity of seedling herbivory interacts with growth-defence trade-offs and herbivore feeding preferences to affect plant community development. : Methods Using 14-d-old seedlings of Trifolium pratense and T. repens, relative growth and susceptibility to herbivory by the snail Helix aspersa was quantified to elucidate putative growth-defence trade-offs for these species. Then mixed assemblages of 14-d-old Trifolium seedlings were exposed to herbivory by zero, two, five or ten snails and determined how variation in the intensity of herbivory affected competitive interactions into the mature phase (as measured by total plant biomass at 120 d old). : Key Results In the absence of herbivory, communities were dominated by T. pratense; a result expected on the basis that it yielded larger and presumably more competitive seedlings. However, when seedlings were exposed to herbivory, the balance of competition shifted. At low levels of herbivory (two snails), both Trifolium species contributed equally to total plant biomass. More intense herbivory (five snails) resulted in almost total mortality of T. pratense and dominance of the mature community by T. repens. The most intense herbivory (ten snails) effectively removed all seedlings from the experimental community. : Conclusions The study illustrates a mechanism whereby spatio-temporal fluctuations in seedling herbivory, when coupled with species-specific variation in competitive ability and sensitivity to herbivore attack, can differentially influence plant recruitment into the mature phase. This mechanism may be a key element in our attempts to understand plant species coexistence, since fluctuations in plant recruitment are fundamental to the many theories that view coexistence as a consequence of a spatio-temporal lottery for dominance over regeneration micro-sites. [ABSTRACT FROM AUTHOR]