Towards a generalized theory of low-frequency sound source localization

Low-frequency sound source localization generates considerable amount of disagreement between audio/acoustics researchers, with some arguing that below a certain frequency humans cannot localize a source with others insisting that in certain cases localization is possible, even down to the lowest audible of frequencies. Nearly all previous work in this area depends on subjective evaluations to formulate theorems for low-frequency localization. This, of course, opens the argument of data reliability, a critical factor that may go some way to explain the reported ambiguities with regard to low-frequency localization. The resulting proposal stipulates that low-frequency source localization is highly dependent on room dimensions, source/listener location and absorptive properties. In some cases, a source can be accurately localized down to the lowest audible of frequencies, while in other situations it cannot. This is relevant as the standard procedure in live sound reinforcement, cinema sound and home-theater surround sound is to have a single mono channel for the low-frequency content, based on the assumption that human’s cannot determine direction in this band. This work takes the first steps towards showing that this may not be a universally valid simplification and that certain sound reproduction systems may actually benefit from directional low-frequency content

Profitability and risk evaluation of novel perennial pasture systems for livestock producers in the high rainfall zone: Context, Approach and Preliminary Results

The decision to invest in pasture improvement raises various questions for the livestock grazier, with the most pertinent being about the potential returns and risks. In the high rainfall zone of south-west Victoria, researchers have trialled novel perennial pasture systems with the aim of substantially increasing on-farm profits whilst simultaneously improving environmental outcomes. Results from the Hamilton EverGraze® proof site have shown potential to greatly improve livestock production. Promotion of the pasture technology is the next step. Key to this process is developing information about profitability and risk regarding the decision to invest in the new pasture. To help meet this need a model of a representative mixed livestock farm system for the region has been developed to generate information about profit, cash wealth and risk to aid extension and help inform decisions. The farm is comprised of a wool and meat producing sheep system and a beef enterprise. Using the model, the performance of two of the novel pasture systems can be evaluated against current practice, and compared to determine which of the two is the most beneficial EverGraze® option for the future. The risk associated with the pasture decision is assessed by considering different price structures and seasonal outcomes, and evaluating these effects on net benefits. Discounted cash flows, net present values and internal rates of return are estimated for the alternative systems, which include the effects of this price and seasonal variability. Preliminary results have been calculated, however further work is needed to confirm these. The method and results of the analysis provide information that is valuable for farm decisions about investing in a new pasture system and provide a basis for future economic analyses at the case study site and elsewhere.Farm Management,

The Effect of Foam Rolling for Three Consecutive Days on Muscular Efficiency and Range of Motion

Background Foam rolling (FR) has been shown to alleviate some symptoms of exercise-induced muscle damage and has been suggested to increase range of motion (ROM) without negatively impacting strength. However, it is unclear what neuromuscular effects, if any, mediate these changes. Methods In a randomized, crossover design, 16 healthy active males completed 2 min of rest or FR of the knee extensors on three consecutive days. Mechanical properties of vastus lateralis (VL) and rectus femoris (RF) were assessed via Tensiomyography. Knee extension maximal voluntary contraction (MVC) and knee flexion ROM were also assessed, and surface electromyography amplitude (RMS) was recorded during a submaximal isometric contraction (50% of MVC). Measures were performed before and after (0, 15, and 30 min) FR or rest. Results MVC was reduced on subsequent days in the rest condition compared to FR (p = 0.002, pη2 = 0.04); ROM was not different across time or condition (p = 0.193, pη2 = 0.01). Stiffness characteristics of the VL were different on the third day of FR (p = 0.002, pη2 = 0.03). RMS was statistically reduced 0, 15, and 30 min after FR compared to rest (p = 0.006, pη2 = 0.03; p = 0.003, pη2 = 0.04; p = 0.002, pη2 = 0.04). Conclusions Following FR, MVC was elevated compared to rest and RMS was transiently reduced during a submaximal task. Excitation efficiency of the involved muscles may have been enhanced by FR, which protected against the decline in MVC which was observed with rest

Reduced Radial Displacement of the Gastrocnemius Medialis Muscle After Electrically Elicited Fatigue

Context: Assessments of skeletal muscle functional capacity often necessitate maximal contractile effort, which exacerbates muscle fatigue or injury. Tensiomyography (TMG) has been investigated as a means to assess muscle contractile function following fatigue; however observations have not been contextualised by concurrent physiological measures. Objective: The aim of the present investigation was to measure peripheral fatigue-induced alterations in mechanical and contractile properties of the plantar flexor muscles through non-invasive TMG concurrently with maximal voluntary contraction (MVC) and passive muscle tension (PMT) in order to validate TMG as a gauge of peripheral fatigue. Design: Pre- and post-test intervention with control. Setting: University laboratory. Participants: Twenty-one healthy male volunteers. Interventions: Subjects plantar flexors were tested for TMG parameters, along with MVC and PMT, before and after either a 5 minute rest period (control) or a 5 minute electrical stimulation intervention (fatigue). Main Outcome Measures: Temporal (contraction velocity) and spatial (radial displacement) contractile parameters of the Gastrocnemius Medialis were recorded through TMG. MVC was measured as an indicator of muscle fatigue and PMT was measured to assess muscle stiffness. Results: Radial displacement demonstrated a fatigue-associated reduction (3.3 ± 1.2 vs. 4.0 ± 1.4 mm vs, p=0.031), while contraction velocity remained unaltered. Additionally, MVC significantly declined by 122.6 ± 104 N (p<0.001) following stimulation (fatigue). PMT was significantly increased following fatigue (139.8 ± 54.3 vs. 111.3 ± 44.6 N, p=0.007).  Conclusion: TMG successfully detected fatigue, evident from reduced MVC, by displaying impaired muscle displacement, accompanied by elevated PMT. TMG could be useful in establishing fatigue status of skeletal muscle without exacerbating the functional decrement of the muscle

Scenario Analysis: Risk and Return of Aluminium Tolerant Lucerne

Lucerne (Medicago sativa) yield is limited by aluminium stress associated with acid soils (Campbell et al. 1988; Scott et al. 2008). With the aid of transgenic technologies, the development of aluminium tolerant (Al Tol) lucerne is proposed. Modelled scenario analysis was conducted to explore the potential net benefits of Al Tol lucerne as part of a grazing system for a sheep production system in the high rainfall zone of south west Victoria

Electrical stimulation of renal nerves for modulating urine glucose excretion in rats

Abstract Background The role of the kidney in glucose homeostasis has gained global interest. Kidneys are innervated by renal nerves, and renal denervation animal models have shown improved glucose regulation. We hypothesized that stimulation of renal nerves at kilohertz frequencies, which can block propagation of action potentials, would increase urine glucose excretion. Conversely, we hypothesized that low frequency stimulation, which has been shown to increase renal nerve activity, would decrease urine glucose excretion. Methods We performed non-survival experiments on male rats under thiobutabarbital anesthesia. A cuff electrode was placed around the left renal artery, encircling the renal nerves. Ureters were cannulated bilaterally to obtain urine samples from each kidney independently for comparison. Renal nerves were stimulated at kilohertz frequencies (1–50 kHz) or low frequencies (2–5 Hz), with intravenous administration of a glucose bolus shortly into the 25–40-min stimulation period. Urine samples were collected at 5–10-min intervals, and colorimetric assays were used to quantify glucose excretion and concentration between stimulated and non-stimulated kidneys. A Kruskal-Wallis test was performed across all stimulation frequencies (α = 0.05), followed by a post-hoc Wilcoxon rank sum test with Bonferroni correction (α = 0.005). Results For kilohertz frequency trials, the stimulated kidney yielded a higher average total urine glucose excretion at 33 kHz (+ 24.5%; n = 9) than 1 kHz (− 5.9%; n = 6) and 50 kHz (+ 2.3%; n = 14). In low frequency stimulation trials, 5 Hz stimulation led to a lower average total urine glucose excretion (− 40.4%; n = 6) than 2 Hz (− 27.2%; n = 5). The average total urine glucose excretion between 33 kHz and 5 Hz was statistically significant (p < 0.005). Similar outcomes were observed for urine flow rate, which may suggest an associated response. No trends or statistical significance were observed for urine glucose concentrations. Conclusion To our knowledge, this is the first study to investigate electrical stimulation of renal nerves to modulate urine glucose excretion. Our experimental results show that stimulation of renal nerves may modulate urine glucose excretion, however, this response may be associated with urine flow rate. Future work is needed to examine the underlying mechanisms and identify approaches for enhancing regulation of glucose excretion.https://deepblue.lib.umich.edu/bitstream/2027.42/143868/1/42234_2018_Article_8.pd

The complexity and difficulty of diagnosing lung cancer: findings from a national primary-care study in Wales

Aim This paper aims to provide a detailed analysis of the diagnostic process of lung cancer from a primary-care perspective. Background Diagnosing lung cancer at a stage where curative treatment is possible remains a challenge. Beginning to understand the complexity and difficulty in the diagnostic journey should enable the development of interventions in order to facilitate timelier diagnosis. Methods A national study of significant events was conducted whereby general practitioners (GPs) in Wales were asked to report data relating to the diagnostic process of recent lung cancer diagnoses using a standard template. Both qualitative and quantitative data were analysed. Findings Case reports were received from 96 general practices on 118 patients. A total of 96 patients (81.4%) presented with respiratory symptoms. A total of 79 patients (66.9%) had a GP-initiated X-ray before diagnosis. A total of 23 patients (19.5%) had a chest X-ray that did not initially show suspicion of lung cancer. A total of 25 patients (21.2%) were diagnosed after a GP-initiated acute admission. Analysis of free-text qualitative data showed that, for many patients, their GP behaved in an exemplary manner. However, for some patients, the GP could have made more of the opportunities presented for timelier diagnosis. There were a number of atypical and complex presentations, where the opportunities for more timely diagnosis were more limited. A variety of causes of diagnostic delays in secondary care were reported. These findings will inform health policy, and will inform the design of interventions to try to facilitate more timely diagnosis for symptomatic patients. We encourage greater compliance with diagnostic guidelines and greater vigilance for patients presenting with atypical symptoms, as well as for patients whose initial chest X-rays are normal

704-4 EDRF-mediated Increases in Conduit Artery Distensibility are Impaired in Chronic Heart Failure

Chronic heart failure (CHF) is associated with reduced EDRF activity in resistance arteries. A similar effect in conduit arteries would reduce their distensibility and increase the load on the compromised heart. We measured pulse wave velocity (PWV), inversely related to distensibility, in the right common iliac artery (RCIA) during acetylcholine (ACh, endothelium-dependent dilator) and adenosine (Ado, endothelium-independent dilator) infusion in 6 patients with CHF (NYHA grades 2–3, EF &lt; 40%, age 50 ± 16 [SD] years, 4 men) and 9 normal subjects (N) (age 49 ± 6 years, 4 men). CHF was due to dilated cardiomyopathy (with normal blood pressure, cholesterol, glucose, and coronary angiograms). PWV, measured from the pressure pulse delay between 2 transducers 5 cm apart, was measured during infusions proximal (P) and distal (D)to the RCIA segment studied. We corrected for BP and other downstream effects by subtracting D from P effects. At baseline, PWV was similar in the two groups (CHF 8.7 ± 1.1; N 9.1 ± 1.5 ms-1). ACh (10-7, 10-6, 10-5mol/L) induced dose-dependent reductions in PWV (-5, -15, -25%) in normals but no change (+ 2, +2, -3%) in CHF (p = 0.0013). Ado (2 × 10-7, 2 × 10-6,2 × 10-5mol/L) induced similar dose-related reductions in PWV in N (-5, -12, -24%) and in CHF (-1, -12, -14%, NS). These data indicate that conduit artery distensibility is increased by ACh-stimulated EDRF activity in normal subjects but not in patients with CHF. This suggests that physiological EDRF-mediated increases in distensibility, as occur during exercise, may be impaired in CHF despite normal resting distensibility