Measurement of Antenna Radiation Pattern using Injection Locking Technique

This paper presents practical results using injection locking to synchronize the local oscillator on a wireless device enabling antenna measurements to be made in a modern anechoic chamber, overcoming the need to connect a cable to the device under tes

Benefits of active transmit balanced antenna fed by differential power amplifier

A differential amplifier feeding a balanced antenna is investigated experimentally. This approach would suit modern RFIC design rather than using a 50Ω unbalanced connection. As such the balun or power-combining network is eliminated resulting in a compact RF front-end design with wider bandwidth and lower losses. Experimental result shows that this technique promises higher output power compared to conventional feeding approach while using same RFIC and same power supply

Fast synchrotron X-ray tomographic quantification of dendrite evolution during the solidification of Mg-Sn alloys

The evolution of dendritic microstructures during the solidification of a Mg-15 wt%Sn alloy was investigated in situ via fast synchrotron X-ray microtomography. To enable these in situ observations a novel encapsulation method was developed and integrated into a fast, pink beam, imaging beamline at Diamond Light Source. The dendritic growth was quantified with time using: solid volume fraction, tip velocity, interface specific surface area, and surface curvature. The influence of cooling rate upon these quantities and primary phase nucleation was investigated. The primary dendrites grew with an 18-branch, 6-fold symmetry structure, accompanied by coarsening. The coarsening process was assessed by the specific surface area and was compared with the existing models. These results provide the first quantification of dendritic growth during the solidification of Mg alloys, confirming existing analytic models and providing experimental data to inform and validate more complex numeric models

Double-layer grid filter for control of wireless signal propagation within buildings

A simple Double–Layer Grid plane wave filter structure is proposed that can provide multiple transmission bands for cellular phone frequencies but with a reflection band for WLAN signals. The approach offers ease of construction making it applicable to building applications. A parametric study using simulation supported by simple experimental data investigates the proposed, novel design

Measurement of fracture toughness of hydrided Zircaloy - 4

Zircaloy-4 is a zirconium alloy that will be used for construction of many of the core components in the replacement research reactor at Lucas Heights. The fracture toughness of the alloy and its radiation-induced reduction over the 40 year planned life of the reactor is an important mechanical property for this application. This study aims to simulate the radiation-induced reduction in fracture toughness by hydriding Zircaloy-4. A range of fracture toughnesses is required to calibrate the sub-size Charpy and small punch (SP) surveillance specimens that will be irradiated over the life of the reactor against standard J1C fracture toughness specimens. Pieces of Zircaloy-4 plate were hydrided in a vessel at a temperature of 520°C, at different pressures for either 10 or 22 hours. Final hydrogen concentrations between 25 wt% ppm and 380 wt% ppm hydrogen were obtained under gaseous atmosphere. The fracture toughness of the hydrided Zircaloy-4 was assessed using sub-size 2.5 mm-thick Charpy, three-point bend J1C and SP tests. The results were correlated to determine the relationship between the J-integral fracture toughness, Charpy impact energy and equivalent fracture strain (εqf) from the SP tests. It was found that as hydrogen concentration and hydride formation increased, the fracture toughness of the alloy generally decreased. The results show there to be a useful relationship between fracture toughness and εqf measured for the SP tests. © Institute of Materials Engineering Australasia Ltd - Materials Forum Volume 27 - Published 2004

Advanced high temperature testing of ferritic pressure vessel steel

This work described three test methods employed to assess the condition of components in high temperature power generation plant. These are stress relaxation on miniature samples from service aged material, low cycle fatugue testing by strain control and Young's Modulus determination by an impulse excitation technique. Data are presentated from tests on 2.25Cr-1Mo virgin and service-aged steel and the applciation of data to life assessment procedures us discussed

A questionnaire to identify patellofemoral pain in the community: an exploration of measurement properties

Background Community-based studies of patellofemoral pain (PFP) need a questionnaire tool that discriminates between those with and those without the condition. To overcome these issues, we have designed a self-report questionnaire which aims to identify people with PFP in the community. Methods Study designs: comparative study and cross-sectional study. Study population: comparative study: PFP patients, soft-tissue injury patients and adults without knee problems. Cross-sectional study: adults attending a science festival. Intervention: comparative study participants completed the questionnaire at baseline and two weeks later. Cross-sectional study participants completed the questionnaire once. The optimal scoring system and threshold was explored using receiver operating characteristic curves, test-retest reliability using Cohen’s kappa and measurement error using Bland-Altman plots and standard error of measurement. Known-group validity was explored by comparing PFP prevalence between genders and age groups. Results Eighty-four participants were recruited to the comparative study. The receiver operating characteristic curves suggested limiting the questionnaire to the clinical features and knee pain map sections (AUC 0.97 95 % CI 0.94 to 1.00). This combination had high sensitivity and specificity (over 90 %). Measurement error was less than the mean difference between the groups. Test–retest reliability estimates suggest good agreement (N = 51, k = 0.74, 95 % CI 0.52–0.91). The cross-sectional study (N = 110) showed expected differences between genders and age groups but these were not statistically significant. Conclusion A shortened version of the questionnaire, based on clinical features and a knee pain map, has good measurement properties. Further work is needed to validate the questionnaire in community samples

Diminished temperature and vegetation seasonality over northern high latitudes

Global temperature is increasing, especially over northern lands (>50° N), owing to positive feedbacks1. As this increase is most pronounced in winter, temperature seasonality (ST)—conventionally defined as the difference between summer and winter temperatures—is diminishing over time2, a phenomenon that is analogous to its equatorward decline at an annual scale. The initiation, termination and performance of vegetation photosynthetic activity are tied to threshold temperatures3. Trends in the timing of these thresholds and cumulative temperatures above them may alter vegetation productivity, or modify vegetation seasonality (SV), over time. The relationship between ST and SV is critically examined here with newly improved ground and satellite data sets. The observed diminishment of ST and SV is equivalent to 4° and 7° (5° and 6°) latitudinal shift equatorward during the past 30 years in the Arctic (boreal) region. Analysis of simulations from 17 state-of-the-art climate models4 indicates an additional STdiminishment equivalent to a 20° equatorward shift could occur this century. How SV will change in response to such large projected ST declines and the impact this will have on ecosystem services5 are not well understood. Hence the need for continued monitoring6 of northern lands as their seasonal temperature profiles evolve to resemble thosefurther south.Lopullinen vertaisarvioitu käsikirjoitu

Mephedrone in adolescent rats: residual memory impairment and acute but not lasting 5-HT depletion

Mephedrone (4-methylmethcathinone, MMC) is a popular recreational drug, yet its potential harms are yet to be fully established. The current study examined the impact of single or repeated MMC exposure on various neurochemical and behavioral measures in rats. In Experiment 1 male adolescent Wistar rats received single or repeated (once a day for 10 days) injections of MMC (30 mg/kg) or the comparator drug methamphetamine (METH, 2.5 mg/kg). Both MMC and METH caused robust hyperactivity in the 1 h following injection although this effect did not tend to sensitize with repeated treatment. Striatal dopamine (DA) levels were increased 1 h following either METH or MMC while striatal and hippocampal serotonin (5-HT) levels were decreased 1 h following MMC but not METH. MMC caused greater increases in 5-HT metabolism and greater reductions in DA metabolism in rats that had been previously exposed to MMC. Autoradiographic analysis showed no signs of neuroinflammation ([125I]CLINDE ligand used as a marker for translocator protein (TSPO) expression) with repeated exposure to either MMC or METH. In Experiment 2, rats received repeated MMC (7.5, 15 or 30 mg/kg once a day for 10 days) and were examined for residual behavioral effects following treatment. Repeated high (30 mg/kg) dose MMC produced impaired novel object recognition 5 weeks after drug treatment. However, no residual changes in 5-HT or DA tissue levels were observed at 7 weeks post-treatment. Overall these results show that MMC causes acute but not lasting changes in DA and 5-HT tissue concentrations. MMC can also cause long-term memory impairment. Future studies of cognitive function in MMC users are clearly warranted. © 2012 PLoS On

The long-term fate of the hip arthrodesis: does it remain a valid procedure for selected cases in the 21st century?

Even in current orthopaedic practice, some cases are still not suitable candidates for hip replacement and hip fusion remains the only option in these highly selected patients. In this retrospective study we describe the long-term clinical outcome, quality of life and radiological evaluation of all adjacent joints in a cohort of 47 hip fusions. The main objective of our study was to show the long-term effects of a fusion. Thirty patients were analysed after an average of 18.2 years (range 6.2–30.5 years) with a mean SMFA of 31.2 (range 9–70). The VAS for pain for the fused hip was an average 1.9 (range 0–8), for the contralateral hip 2.0 (0–8), for the ipsilateral knee 2.0 (0–8), for the contralateral knee 1.8 (0–8) and for the lower back 3.6 (0–8). Average walking distance was 115 minutes (range 10–unlimited). Although the hip arthrodesis has lost popularity, it still is an option for the young patient with severe hip disorders, while leaving the possibility to perform a THA at a later stage. If the arthrodesis is performed with an optimal alignment of the leg, complaints from the adjacent joints are minimal, even in the long-term, and an acceptable quality of life can be obtained. We believe that in highly selected cases a hip fusion, even in current practice, is still a valid option