The contribution of personal audio system use and commuting by bus on daily noise dose.

BACKGROUND: For many young people, exposure to music from personal audio system use may represent a significant component of daily noise dose. Moreover, there is increasing concern for the hearing of those who listen at high volumes. The purpose of this study was to determine the noise levels experienced on commuter buses, and to investigate how these impact on the volume-setting behavior of young adult personal audio system users. METHODS: A questionnaire was used to probe transport use, personal audio system-listening behaviors and the extent of understanding about noise-induced hearing loss. The influence of bus noise on volume-setting behavior was determined by measuring, in a lab setting, the sound-level preferences of participants when listening to their favorite song, a generic song, or a podcast in the absence and presence of various levels of bus noise, simulated using output-adjusted recordings made of bus noise. Statistical analysis was conducted using analysis of variance. RESULTS: While the bus noise itself was below 85 dB Leq, as the sound level of the buses increased, so did the percentage of commuters who were found to exceed the equivalent of 8 hours of exposure at 85 dB Leq. IMPLICATIONS: Investment in buses with lower noise levels or the use of noise-canceling or noise-occluding headphones would help to reduce the likelihood of noise-induced hearing loss for bus commuters.

Reference Protocol to Assess Analytical Performance of Higher Order Structural Analysis Measurements: Results from an Interlaboratory Comparison.

Measurements of protein higher order structure (HOS) provide important information on stability, potency, efficacy, immunogenicity, and biosimilarity of biopharmaceuticals, with a significant number of techniques and methods available to perform these measurements. The comparison of the analytical performance of HOS methods and the standardization of the results is, however, not a trivial task, due to the lack of reference protocols and reference measurement procedures. Here, we developed a protocol to structurally alter and compare samples of somatropin, a recombinant biotherapeutic, and describe the results obtained by using a number of techniques, methods and in different laboratories. This, with the final aim to provide tools and generate a pool of data to compare and benchmark analytical platforms and define method sensitivity to structural changes. Changes in somatropin HOS, induced by the presence of zinc at increasing concentrations, were observed, both globally and at more localized resolution, across many of the methods utilized in this study and with different sensitivities, suggesting the suitability of the protocol to improve understanding of inter- and cross-platform measurement comparability and assess analytical performance as appropriate.

The role of subchondral bone, and its histomorphology, on the dynamic viscoelasticity of cartilage, bone and osteochondral cores.

OBJECTIVE: Viscoelastic properties of articular cartilage have been characterised at physiological frequencies. However, studies investigating the interaction between cartilage and subchondral bone and the influence of underlying bone histomorphometry on the viscoelasticity of cartilage are lacking. METHOD: Dynamic Mechanical Analysis (DMA) has been used to quantify the dynamic viscoelasticity of bovine tibial plateau osteochondral cores, over a frequency sweep from 1 to 88 Hz. Specimens (approximately aged between 18 and 30 months) were neither osteoarthritic nor otherwise compromised. A maximum nominal stress of 1.7 MPa was induced. Viscoelastic properties of cores have been compared with that of its components (cartilage and bone) in terms of the elastic and viscous components of both structural stiffness and material modulus. Micro-computed tomography scans were used to quantify the histomorphological properties of the subchondral bone. RESULTS: Opposing frequency-dependent loss stiffness, and modulus, trends were witnessed for osteochondral tissues: for cartilage it increased logarithmically (P < 0.05); for bone it decreased logarithmically (P < 0.05). The storage stiffness of osteochondral cores was logarithmically frequency-dependent (P < 0.05), however, the loss stiffness was typically frequency-independent (P > 0.05). A linear relationship between the subchondral bone plate (SBP) thickness and cartilage thickness (P < 0.001) was identified. Cartilage loss modulus was linearly correlated to bone mineral density (BMD) (P < 0.05) and bone volume (P < 0.05). CONCLUSION: The relationship between the subchondral bone histomorphometry and cartilage viscoelasticity (namely loss modulus) and thickness, have implications for the initiation and progression of osteoarthritis (OA) through an altered ability of cartilage to dissipate energy.

Lumbar model generator: a tool for the automated generation of a parametric scalable model of the lumbar spine.

Low back pain is a major cause of disability and requires the development of new devices to treat pathologies and improve prognosis following surgery. Understanding the effects of new devices on the biomechanics of the spine is crucial in the development of new effective and functional devices. The aim of this study was to develop a preliminary parametric, scalable and anatomically accurate finite-element model of the lumbar spine allowing for the evaluation of the performance of spinal devices. The principal anatomical surfaces of the lumbar spine were first identified, and then accurately fitted from a previous model supplied by S14 Implants (Bordeaux, France). Finally, the reconstructed model was defined according to 17 parameters which are used to scale the model according to patient dimensions. The developed model, available as a toolbox named the lumbar model generator, enables generating a population of models using subject-specific dimensions obtained from data scans or averaged dimensions evaluated from the correlation analysis. This toolbox allows patient-specific assessment, taking into account individual morphological variation. The models have applications in the design process of new devices, evaluating the biomechanics of the spine and helping clinicians when deciding on treatment strategies.

Maternal engineered nanomaterial inhalation during gestation alters the fetal transcriptome.

BACKGROUND: The integration of engineered nanomaterials (ENM) is well-established and widespread in clinical, commercial, and domestic applications. Cardiovascular dysfunctions have been reported in adult populations after exposure to a variety of ENM. As the diversity of these exposures continues to increase, the fetal ramifications of maternal exposures have yet to be determined. We, and others, have explored the consequences of ENM inhalation during gestation and identified many cardiovascular and metabolic outcomes in the F1 generation. The purpose of these studies was to identify genetic alterations in the F1 generation of Sprague-Dawley rats that result from maternal ENM inhalation during gestation. Pregnant dams were exposed to nano-titanium dioxide (nano-TiO2) aerosols (10 ± 0.5 mg/m3) for 7-8 days (calculated, cumulative lung deposition = 217 ± 1 µg) and on GD (gestational day) 20 fetal hearts were isolated. DNA was extracted and immunoprecipitated with modified chromatin marks histone 3 lysine 4 tri-methylation (H3K4me3) and histone 3 lysine 27 tri-methylation (H3K27me3). Following chromatin immunoprecipitation (ChIP), DNA fragments were sequenced. RNA from fetal hearts was purified and prepared for RNA sequencing and transcriptomic analysis. Ingenuity Pathway Analysis (IPA) was then used to identify pathways most modified by gestational ENM exposure. RESULTS: The results of the sequencing experiments provide initial evidence that significant epigenetic and transcriptomic changes occur in the cardiac tissue of maternal nano-TiO2 exposed progeny. The most notable alterations in major biologic systems included immune adaptation and organismal growth. Changes in normal physiology were linked with other tissues, including liver and kidneys. CONCLUSIONS: These results are the first evidence that maternal ENM inhalation impacts the fetal epigenome.

Effect of frequency on crack growth in articular cartilage.

Cracks can occur in the articular cartilage surface due to the mechanical loading of the synovial joint, trauma or wear and tear. However, the propagation of such cracks under different frequencies of loading is unknown. The objective of this study was to determine the effect of frequency of loading on the growth of a pre-existing crack in cartilage specimens subjected to cyclic tensile strain. A 2.26mm crack was introduced into cartilage specimens and crack growth was achieved by applying a sinusoidally varying tensile strain at frequencies of 1, 10 and 100Hz (i.e. corresponding to normal, above normal and up to rapid heel-strike rise times, respectively). These frequencies were applied with a strain of between 10-20% and the crack length was measured at 0, 20, 50, 100, 500, 1000, 5000 and 10,000 cycles of strain. Crack growth increased with increasing number of cycles. The maximum crack growth was 0.6 ± 0.3 (mean ± standard deviation), 0.8 ± 0.2 and 1.1 ± 0.4mm at frequencies of 1, 10 and 100Hz, respectively following 10,000 cycles. Mean crack growth were 0.3 ± 0.2 and 0.4 ± 0.2 at frequencies of 1 and 10Hz, respectively. However, this value increased up to 0.6 ± 0.4mm at a frequency of 100Hz. This study demonstrates that crack growth was greater at higher frequencies. The findings of this study may have implications in the early onset of osteoarthritis. This is because rapid heel-strike rise times have been implicated in the early onset of osteoarthritis.

Thulium-fiber-laser-pumped, high-peak-power, picosecond, mid-infrared orientation-patterned GaAs optical parametric generator and amplifier.

We report a high-peak-power, picosecond, mid-infrared optical parametric generator (OPG) and optical parametric amplifier (OPA) based on orientation-patterned gallium arsenide pumped by a thulium:fiber master-oscillator-power-amplifier employing direct diode-seeded amplification. An OPG tuning range of 2550-2940 nm (signal) and 5800-8300 nm (idler) is demonstrated with peak powers as high as 3 (signal) and 2 kW (idler), and with pulse energies of 0.26 and 0.16 µJ, respectively. When seeded with a 0.6 cm-1 linewidth tunable Cr:ZnSe laser, the OPA idler linewidth is narrowed to 1.4 cm-1 and a small-signal parametric gain of 60 dB is achieved. A maximum peak power of 13.3 (signal) and 3.2 kW (idler) is obtained at an overall conversion efficiency of 36%. The corresponding maximum pulse energies for the signal and idler are 1.07 and 0.26 µJ, respectively.

Cognitive decision strategies adopted by consumers in reminder difference tests: Influence of the authenticity test.

Discrimination tests are used in food companies to quantify small differences between products. Within the diversity of methods available, some are quicker to conduct, whereas others are more sensitive or statistically powerful. One class of methods includes the reminder tasks in which the reference product is given before tasting the actual test stimuli. During the task, such a 'reminder' can be compared directly to each test stimulus, or alternatively, only serve to prime the memory of the judge without being taken into account in decision-making. Previous research with trained judges provided evidence for the latter process while research with untrained consumers has provided some evidence for the former process. Two studies were conducted with untrained consumers using the A Not-AR and 2-AFCR reminder tasks. Objectives were to determine the decision strategies used in, and the relative sensitivity of the tasks. In addition, the use of an "authenticity test" was explored to see if this has a positive effect on test performance. In the first study, mayonnaise and ice tea with small stimulus differences (d'<1) were used in A Not-AR and 2-AFCR. Results were compared to those from A Not-A and 2-AFC tasks, with and without an authenticity test. It was difficult to draw clear conclusions on the decision strategy used, though the use of an authenticity test increased the sensitivity for these small differences, as it improved the performance of 6 out of 8 tests. In the second study, ice teas with larger stimulus differences (at two levels) were tested using the A Not-AR and 2-AFCR tasks, in comparison to the same-different task. The results showed that consumers use the less optimal strategies and that the authenticity test decreases performance, which is contradictory to the results of the first study. It seems that for very small stimulus differences the authenticity test can improve performance, but with larger differences the authenticity test decreases performance; it seems to confuse the judges.

Fatigue strength of bovine articular cartilage-on-bone under three-point bending: the effect of loading frequency.

BACKGROUND: The objective of this study was to determine the influence of loading frequency on the failure of articular cartilage-on-bone specimens under three-point bending. METHODS: In this study, cyclic three-point bending was used to introduce failure into cartilage-on-bone specimens at varying loading frequencies. Sinusiodally varying maximum compressive loads in the range 40-130 N were applied to beam-shaped cartilage-on-bone specimens at frequencies of 1, 10, 50 and 100 Hz. RESULTS: The number of cycles to failure decreased when loading frequency increased from normal and above gait (1 and 10 Hz) to impulsive loading frequencies (50 and 100 Hz). It was found that 67 and 27% of the specimens reached run-out at loading of 10,000 cycles at frequencies of 1 and 10 Hz, respectively. However, 0% of the specimens reached run-out at loading frequencies of 50 and 100 Hz. CONCLUSION: The results indicate that increasing the loading frequency reduces the ability of specimens to resist fracture during bending. The findings underline the importance of the loading frequency concerning the failure of articular cartilage-on-bone and it may have implications in the early onset of osteoarthritis.

Raman-shifted wavelength-selectable pulsed fiber laser with high repetition rate and high pulse energy in the visible.

A high-pulse-energy, diffraction-limited, wavelength-selectable, visible source, based on Raman frequency shifting of a frequency-doubled Yb-doped fiber laser, has been studied. The relative length-scaling laws of Raman gain and self-phase modulation push the design towards short fiber lengths with large core size. It is experimentally demonstrated that the Raman clean-up effect in a graded-index multi-mode fiber is not sufficient to obtain diffraction-limited beam quality in the short fiber length. Thus, a large-core photonic crystal fiber is used to maintain diffraction-limited performance and output pulse energies of ~1 µJ, at a 1-MHz repetition rate and 1.3-ns pulse-width are successfully achieved. This step-tunable visible source should find applications in photoacoustic microscopy.

Viscoelastic properties of human bladder tumours.

The urinary bladder is an organ which facilitates the storage and release of urine. The bladder can develop tumours and bladder cancer is a common malignancy throughout the world. There is a consensus that there are differences in the mechanical properties of normal and malignant tissues. However, the viscoelastic properties of human bladder tumours at the macro-scale have not been previously studied. This study investigated the viscoelastic properties of ten bladder tumours, which were tested using dynamic mechanical analysis at frequencies up to 30Hz. The storage modulus ranged between 0.052MPa and 0.085MPa while the loss modulus ranged between 0.019MPa and 0.043MPa. Both storage and loss moduli showed frequency dependent behaviour and the storage modulus was higher than the loss modulus for every frequency tested. Viscoelastic properties may be useful for the development of surgical trainers, surgical devices, computational models and diagnostic equipment.

Fiber-laser-pumped, high-energy, mid-IR, picosecond optical parametric oscillator with a high-harmonic cavity.

We demonstrate the generation of high-energy, mid-IR, picosecond pulses in a high-harmonic-cavity optical parametric oscillator (OPO) that has a relatively compact cavity with a length that is a small fraction of that required to match the pump repetition rate. The OPO, based on an MgO-doped periodically poled LiNbO3 crystal, is pumped by a fiber master-oscillator-power-amplifier system employing direct amplification and delivering 11-µJ, 150-ps pulses at 1035 nm. For a 1.554-m-long OPO cavity, resonating near-infrared signal pulses with a repetition rate that is the 193rd harmonic of the 1-MHz pump are demonstrated. The mid-infrared idler output pulses, tunable from 2300 nm to 3500 nm, are generated at a 1-MHz repetition rate and have energies as high as 1.5 µJ.

Effect of the variation of loading frequency on surface failure of bovine articular cartilage.

BACKGROUND: Mechanical loading of synovial joints can damage the articular cartilage surface and may lead to osteoarthritis. It is unknown if, independent of load, frequency alone can cause failure in cartilage. This study investigated the variation of articular cartilage surface damage under frequencies associated with normal, above normal and traumatic loading frequencies. METHOD: Cartilage on bone, obtained from bovine shoulder joints, was tested. Damage was created on the cartilage surface through an indenter being sinusoidally loaded against it at loading frequencies of 1, 10 and 100 Hz (i.e., relevant to normal, above normal and up to rapid heel-strike rise times, respectively). The frequencies were applied with a maximum load in the range 60-160 N. Surface cracks were marked with India ink, photographed and their length measured using image analysis software. RESULTS: Surface damage increased significantly (P < 0.0001) with frequency throughout all load ranges investigated. The dependence of crack length, c, on frequency, f, could be represented by, c=A(log10(f))2+B(log10(f))+Dc=A(log10(f))2+B(log10(f))+D where A = 0.006 ± 0.23, B = 0.62 ± 0.23 and D = 0.38 ± 0.51 mm (mean ± standard deviation). CONCLUSION: The increase in crack length with loading frequency indicated that, increased loading frequency can result in cartilage becoming damaged. The results of this study have implications in the early stages of osteoarthritis.

Responsible corporate change: detecting and managing employee stress.

BACKGROUND: All 120 health and safety inspectors employed by the New Zealand regulatory agency had their jobs disestablished during a restructuring process and were required to undergo an assessment process with tight time frames. AIMS: To report on psychological morbidity during the transition to change. METHODS: The Hospital Anxiety and Depression Scale (HADS) questionnaire was emailed to all 120 current inspectors to measure levels of anxiety (HAD-A) and depression (HAD-D). A score of <7 is in the normal range, scores of between 8 and 10 are suggestive of an anxiety (HADS-A) or mood (HADS-D) disorder and a score of >11 is indicative of a clinical disorder. RESULTS: Replies were received from 36% (43) of the inspectors. Of the 40 usable responses, 47% (19) and 55% (22), respectively, had HAD-A and HAD-D scores greater than the case cut-off. Only 28% (11) and 15% (6), respectively, had scores that would be considered normal. CONCLUSIONS: The high scores evident in this sample are comparable to those found in patients with serious psychopathology. Change managers should recognize that the onus for primary prevention lies with the organization, in this case designing an assessment process that takes place over a reasonable time frame. They should also realize the requirement for the active monitoring of stress.

Surgery for the correction of hallux valgus: minimum five-year results with a validated patient-reported outcome tool and regression analysis.

This study sought to determine the medium-term patient-reported and radiographic outcomes in patients undergoing surgery for hallux valgus. A total of 118 patients (162 feet) underwent surgery for hallux valgus between January 2008 and June 2009. The Manchester-Oxford Foot Questionnaire (MOXFQ), a validated tool for the assessment of outcome after surgery for hallux valgus, was used and patient satisfaction was sought. The medical records and radiographs were reviewed retrospectively. At a mean of 5.2 years (4.7 to 6.0) post-operatively, the median combined MOXFQ score was 7.8 (IQR:0 to 32.8). The median domain scores for pain, walking/standing, and social interaction were 10 (IQR: 0 to 45), 0 (IQR: 0 to 32.1) and 6.3 (IQR: 0 to 25) respectively. A total of 119 procedures (73.9%, in 90 patients) were reported as satisfactory but only 53 feet (32.7%, in 43 patients) were completely asymptomatic. The mean (SD) correction of hallux valgus, intermetatarsal, and distal metatarsal articular angles was 18.5° (8.8°), 5.7° (3.3°), and 16.6° (8.8°), respectively. Multivariable regression analysis identified that an American Association of Anesthesiologists grade of >1 (Incident Rate Ratio (IRR) = 1.67, p-value = 0.011) and recurrent deformity (IRR = 1.77, p-value = 0.003) were associated with significantly worse MOXFQ scores. No correlation was found between the severity of deformity, the type, or degree of surgical correction and the outcome. When using a validated outcome score for the assessment of outcome after surgery for hallux valgus, the long-term results are worse than expected when compared with the short- and mid-term outcomes, with 25.9% of patients dissatisfied at a mean follow-up of 5.2 years.

The process of EDC-NHS Cross-linking of reconstituted collagen fibres increases collagen fibrillar order and alignment.

We describe the production of collagen fibre bundles through a multi-strand, semi-continuous extrusion process. Cross-linking using an EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide), NHS (N-hydroxysuccinimide) combination was considered. Atomic Force Microscopy (AFM) and Raman spectroscopy focused on how cross-linking affected the collagen fibrillar structure. In the cross-linked fibres, a clear fibrillar structure comparable to native collagen was observed which was not observed in the non-cross-linked fibre. The amide III doublet in the Raman spectra provided additional evidence of alignment in the cross-linked fibres. Raman spectroscopy also indicated no residual polyethylene glycol (from the fibre forming buffer) or water in any of the fibres.

Frequency dependent viscoelastic properties of porcine bladder.

The aim of this study was to measure the viscoelastic properties of bladder tissue. Porcine bladders were dissected into rectangular strips and loops. Dynamic Mechanical Analysis was used to measure the viscoelastic properties of the bladder tissue (storage and loss stiffness) tested in a frequency range of up to 10 Hz. Storage stiffness was found to be consistently higher than loss stiffness. Average storage stiffness was found to be 1.89 N/mm and 0.74 N/mm for looped and rectangular samples, respectively. Average loss stiffness was found to be 0.24 N/mm and 0.11 N/mm for looped and rectangular samples, respectively. The results of this study are important for computational modelling of the bladder and for ensuring that engineered bladder tissues have physiological viscoelastic properties.

Chewing, rumen pool characteristics, and lactation performance of dairy cows fed 2 concentrations of a corn wet-milling coproduct with different forage sources.

We used a novel corn wet-milling coproduct [CMP; approximately 70% dry matter, 28% crude protein, 36% neutral detergent fiber (NDF), and 18% nonstructural carbohydrates] in diets formulated to contain 18.4% forage NDF, 17.4% crude protein, 20.2% starch, and 3.7% sugar. Six primiparous, rumen-cannulated Jersey cows were assigned to a 6 × 6 Latin square design with a 2 × 3 factorial arrangement of treatments. Diets were formulated to contain 20 and 30% CMP with 3 forage sources [corn silage (CS) and 40.5% NDF, CS replaced with 10% alfalfa hay (AH) and 45.0% NDF, or CS replaced with 7% grass hay (GH) and 67.4% NDF], with each providing 18.4% forage NDF in the diet. Total-tract digestibilities of NDF, N, and organic matter were not affected by treatment. Similarly, no treatment effects were detected for kinetics of NDF disappearance in situ from CMP or respective forage source or for N disappearance in situ from CMP. Grass hay increased total and liquid pool size of rumen contents compared with AH (by 3.2 and 3.0kg, respectively). Total time spent chewing increased in cows fed GH by over 35min compared with those fed AH, partially due to a trend for increased minutes spent ruminating. Mean particle size of rumen contents also tended to be higher in the GH (0.55mm) than AH (0.69mm) diets. No effects on production of milk or milk components were detected, but dry matter intake (DMI) tended to decrease when CMP increased from 20 to 30%. Gross feed efficiency (fat-corrected milk/DMI) tended to be greater when cows were fed AH and GH compared with CS and was greater for AH than GH diets. In diets containing low starch, increasing CMP from 20 to 30% potentially maintained similar fat-corrected milk production with lower DMI. However, more consideration also should be given to interactions among forages with respect to fill, digestion, and passage of fiber with increased inclusion rates of CMP.

Rigid intramedullary nail fixation of femoral fractures in adolescents: what evidence is available?

BACKGROUND: Femoral fracture in adolescents is a significant injury. It is generally agreed that operative fixation is the treatment of choice, and rigid intramedullary nail fixation is a treatment option. However, numerous types of rigid nails to fix adolescent femoral fractures have been described. Hence, the aim of this paper was to collate and evaluate the available evidence for managing diaphyseal femoral fractures in adolescents using rigid intramedullary nails. MATERIALS AND METHODS: A literature search was undertaken using the healthcare database website ( http://www.library.nhs.uk/hdas ). Medline, CINAHL, Embase, and the Cochrane Library databases were searched to identify prospective and retrospective studies of rigid intramedullary nail fixation in the adolescent population. RESULTS: The literature search returned 1,849 articles, among which 51 relevant articles were identified. Of these 51 articles, 23 duplicates were excluded, so a total of 28 articles were reviewed. First-generation nails had a high incidence of limb length discrepancy (Küntscher 5.8 %, Grosse-Kempf 9 %), whilst second-generation nails had a lower incidence (Russell-Taylor 1.7 %, AO 2.6 %). Avascular necrosis was noted with solid Ti nails (2.6 %), AO femoral nails (1.3 %) and Russell-Taylor nails (0.85 %). These complications have not been reported with the current generation of nails. CONCLUSIONS: Rigid intramedullary nail fixation of femoral fractures in adolescents is a useful procedure with good clinical results. A multiplanar design and lateral trochanteric entry are key to a successful outcome of titanium alloy nail fixation.

Mechanical testing of lid speculae and relationship to postoperative ptosis.

AIMS: Postoperative lid malpositions are known complications of routine intraocular surgery and were previously attributed to the use of a bridle suture or the myotoxic effect of retrobulbar or peribulbar anaesthetics. However, lid malpositions are still seen under topical anaesthesia. Recent studies have implicated the lid speculum as a factor. Patients with narrower vertical palpebral apertures have been shown to develop postoperative ptosis more frequently, but the reason is unknown. This is the first study to determine the forces exerted by lid speculae over a range of palpebral apertures. METHODS: Mechanical testing was undertaken using a Bose 3200 materials testing machine. Tests were undertaken on four disposable and four reusable speculae. The force used to compress each speculum was compared over a range of displacements. A two-sample t-test was used to compare the stiffness of the two types of speculum. RESULTS: The stiffness of the reusable speculum was significantly greater than the disposable speculum (P=0.002). The stiffness of each speculum was greatest at the range of displacement corresponding to the narrower palpebral apertures. CONCLUSIONS: Different speculae exert significantly different forces on patients' eyelids during surgery. The patients who experience the greatest compression from the speculae are those with the smallest palpebral apertures. This may explain why these patients are more likely to develop postoperative lid malpositions.