828 research outputs found
Radioactive method enables determination of surface areas rapidly and accurately
Radioactive krypton adsorption technique is used to determine the surface area of more than one sample of material simultaneously
Recommended from our members
On the interpretation of gravity variations in the presence of active hydrothermal systems: Insights from the Nisyros Caldera, Greece
We report on short-term (over tens of minutes) residual gravity changes recorded at the restless Nisyros caldera in Greece via a series of discrete measurements at benchmarks within or in proximity to a hydrothermal area located along the caldera floor. The obtained time series reveal sinusoidal gravity variations with amplitudes of up to 25 μGal and wavelengths of 40–50 min. Degassing of a magmatic source coupling into (shallow) hydrothermal systems including the ascent of steam pockets and transient pressure variations during steam/liquid interface propagation appear to be the most likely causative process for the observed short-term variations. We assess standard protocols of microgravity surveys for hazard assessment in volcanic areas in the light of these findings and propose additional techniques, such as continuous gravimetry, for the discrimination of hydrothermal signals from deeper-seated, i.e. magmatic, signals during gravity monitoring of restless volcanoes hosting active hydrothermal systems
The Hector Mine, California, Earthquake of 16 October 1999: Introduction to the Special Issue
The Hector Mine, California, earthquake (M_w 7.1) struck the Mojave Desert at 09:46 UTC, 16 October 1999. The earthquake occurred approximately 55 km northwest of the town of Twentynine Palms, California, and about 200 km east-northeast of Los Angeles (Fig. 1). The shock was widely felt throughout southern California, southern Nevada, western Arizona, and northernmost Baja California, Mexico. The Hector Mine earthquake, like the M_w 7.3 Landers earthquake seven years earlier, was associated with fault rupture in the eastern California shear zone (ECSZ) (Fig. 1), which is an approximately 80-km-wide zone of deformation that accommodates about 24% of the relative Pacific–North American plate motion (Sauber et al., 1986, 1994; Dokka and Travis, 1990; Savage et al., 1990, 2001; Gan et al., 2000; Miller et al., 2001). A block diagram highlighting some of the basic aspects of the Hector Mine earthquake is presented in Figure 2. A preliminary summary of the Hector Mine earthquake, its effects, and the response of the geoscience community is presented by Scientists from the U.S. Geological Survey; Southern California Earthquake Center, and California Division of Mines and Geology (USGS, SCEC, and CDMG, 2000)
Population structure and morphology of Canarium (Canarium) incisum and Canarium (Canarium) esculentum (Mollusca: Neostromboidae: Strombidae) from the Philippines with preliminary notes on aperture colouration based on DArTseq data
Canarium (Canarium) incisum and Canarium (Canarium) esculentum are small members of the molluscan Strombidae family. Little is known of their population structure. Therefore, we explored this using samples from a population of each. The first sample from Corong Corong Beach, El Nido, Philippines, consisted of 81 adult C. incisum, of which 33 were female and 48 were male. The second sample from Olango Island, Philippines consisted of 73 adult C. esculentum, of which 40 were female and 33 were male. Bias in sex ratio between species was not significant. However, there was bias in sex ratio within species, where males from both species were smaller in axial length than females. We found no evidence of pseudohermaphroditism. The black colouration of the aperture is a phenotype shared by many stromboidians, and 7.4% of C. incisum population exhibited this trait, while the C. esculentum population contained 50.1% black apertures specimens. Preliminary DArTseq analysis indicates that organisms with the black aperture colouration are nested within the populations. Our study fills a knowledge gap on C. incisum and C. esculentum population structure, and gives greater insights to size dynamics of stromboidian taxa in general
Technologies and Operations for High Voltage Corona Detection with UAVs
Autonomous UAV transmission line inspection served as a reference mission for NASA demonstration of UAV deployment for economic benefit; this paper reports corona sensing advances in development of that reference mission. Unmanned aerial vehicles can serve as a platform for autonomous sensing and location of high voltage coronal discharge. Simple processing of commercial corona camera imagery can automate discharge localization and documentation. Inexpensive ultraviolet point sensors can sense discharge when carried close to the defect with a UAV. Augmented with a parabolic mirror, point sensor range can be increased to a safe inspection standoff distance, at the cost of a narrowed field of view. Results from a test flight of an augmented UV sensor are described. The imaging approach is superior in sensitivity and acquisition time, while the point sensor approach has superior size, weight, cost and durability advantages
The management of menopausal symptoms in women following treatment for cancer at a specialist menopause service.
OBJECTIVE: The aim of this study was to identify prescribing patterns at a specialist menopause service in a central London teaching hospital for women following treatment for a malignancy. STUDY DESIGN: This was a prospective cohort study with data collected over a seven-month period from December 2019 to June 2020. All women reviewed at the specialist menopause services following treatment of a malignancy, BRCA carriers and Lynch syndrome were included in the study, with management options divided into three categories: hormonal, non-hormonal and no treatment. MAIN OUTCOME MEASURES: The primary outcome of this study was to identify prescribing patterns for all women reviewed following a diagnosis of a malignancy, as well as those with genetic mutations necessitating risk-reducing prophylactic bilateral salpingo-oopherectomy (BSO). RESULTS: Altogether 71 women were included in this study, with the majority of women post management of a non-gynaecological malignancy (51/71, 72%), of which breast cancer was the most common (37/71, 52%). While non-hormonal treatment was the most popular among those treated for breast cancer, for all other malignancies, hormonal treatment was more widespread. Fourteen women also had genetic mutations, with all of these women commencing hormonal treatment post risk reducing surgery. CONCLUSION: With the exception of those with a history of hormone-sensitive breast cancer, the use of hormonal treatment for menopausal symptoms remained widespread. While this was a relatively small study, the need for long-term follow-up across specialist menopause services, to assess the risk of recurrence is vital
Autonomous Inspection of Electrical Transmission Structures with Airborne UV Sensors and Automated Air Traffic Management
This report details test and measurement flights to demonstrate autonomous UAV (Unmanned Aerial Vehicle) inspection of high-voltage electrical transmission structures. A UAV built with commercial, off-the-shelf hardware and software, supplemented with custom sensors and logging software, measured ultraviolet (UV) emissions from a test generator placed on a low-altitude substation and a medium-altitude switching tower. Since corona discharge precedes catastrophic electrical faults on high-voltage structures, detection and geolocation of ultraviolet emissions is needed to develop a UAV-based self-diagnosing power grid. Signal readings from an onboard ultraviolet sensor were validated during flight with a commercial corona camera. Geolocation was accomplished with onboard GPS; the UAV position was logged to a local ground station and transmitted in real time to a NASA server for tracking in the national airspace. The method has practicality and relevance but not adequacy; either improved UAV position determination technology or increased sensor range is needed to enable broad deployment of this method
Autonomous Inspection of Electrical Transmission Structures with Airborne UV Sensors - NASA Report on Dominion Virginia Power Flights of November 2016
The report details test and measurement flights to demonstrate autonomous UAV inspection of high voltage electrical transmission structures. A UAV built with commercial, off-the-shelf hardware and software, supplemented with custom sensor logging software, measured ultraviolet emissions from a test generator placed on a low-altitude substation and a medium-altitude switching tower. Since corona discharge precedes catastrophic electrical faults on high-voltage structures, detection and geolocation of ultraviolet emissions is needed to develop a UAV-based self-diagnosing power grid. Signal readings from an onboard ultraviolet sensor were validated during flight with a commercial corona camera. Geolocation was accomplished with onboard GPS; the UAV position was logged to a local ground station and transmitted in real time to a NASA server for tracking in the national airspace
Primary care use of antipsychotic drugs: an audit and intervention study
BACKGROUND: Concerns regarding the use of antipsychotic medication in secondary care suggested an examination of primary care prescribing. AIM: To audit and intervene in the suboptimal prescribing of antipsychotic drugs to primary care patients. DESIGN OF STUDY: Cross-sectional prevalence: subsequent open treatment intervention. SETTING: Seven of the 29 practices in the Eastern Hull Primary Care Trust. METHODS: Criteria for best practice were developed, against which prescribing standards were tested via audit. Patients identified as suboptimally prescribed for were invited to attend an expert review for intervention. RESULTS: 1 in 100 of 53,000 patients was prescribed antipsychotic treatment. Diagnoses indicating this were impossible to ascertain reliably. Half the regimes failed one or more audit criteria, leaving diagnosis aside. Few practices agreed to patients being approached: of 179 invitations sent, only 40 patients attended. Of 32 still taking an antipsychotic drug, 26 required changes. Mean audit criteria failed were 3.4, lack of psychotic disorder diagnosis and problematic side effects being most frequent. Changes were fully implemented in only 16 patients: reasons for complete or partial failure to implement recommendations included the wishes or inaction of patients and professionals, and worsening of symptoms including two cases of antipsychotic withdrawal syndrome. CONCLUSION: Primary care prescribing of antipsychotic drugs is infrequent, but most is unsatisfactory. Intervention is hampered by pluralistic reluctance: even with expert guidance, rationalisation is not without risk. Use of antipsychotic drugs in primary care patients whose diagnosis does not warrant this should be avoided. HOW THIS FITS IN: This study adds to concerns regarding high levels of off-licence use of potentially harmful medication. It adds evidence of major difficulties in rationalizing suboptimal regimes despite expert input. Relevance to the clinician is that it is better to avoid such regimes in the first place especially if there is no clear 'exit strategy': if in doubt, seek a specialist opinion
Recommended from our members
Anticoagulant resistance in Norway rats conferred by VKORC1 mutations in south-east England
Anticoagulant resistance was discovered in Norway rats in the United Kingdom nearly 70 years ago, and since then the number of resistance mutations and resistance foci has increased. In no other country are mutations that are thought to confer serious practical resistance so widespread. Numerous studies have shown multiple resistance genotypes and phenotypes across south-east England. Despite this, the extent of these resistance foci and the resistance factors possessed by these rats are not known. The experiments described herein were designed to reveal the extent and impact of resistance mutations in south-east England. 304 tissue and faecal samples were taken from rats across the study area, in order to identify and delimit foci of VKORC1 resistance conferred by mutations in the VKORC1 gene. The L120Q resistance mutation was found to be prevalent across the study area, with the majority of rats possessing the homozygous form of the mutation, suggesting that for
years, resistance has been selected for through use of ineffective second generation anticoagulant rodenticides (SGARs). Two strains of L120Q-resistant laboratory rats were dosed with SGARs and their prothrombin times (PT) measured, and resistance factors generated by comparison with data from susceptible strains. L120Q in its strongest form was found to confer practical resistance to bromadiolone and difenacoum, but not to resistance
breakers such as brodifacoum. Finally, field trials were carried out in the L120Q resistance focus of central-southern England, which showed conclusively that brodifacoum is efficacious against L120Q-resistant rats in both Berkshire and Hampshire. The UK rodenticide stewardship scheme, proposed by the Campaign for Responsible Rodenticide Use (CRRU) will see “resistance breaking” SGARs available for use against Norway rats only by competent users as of April 2017. Results indicate this development is both timely and necessary for proactive Norway rat control in the UK
- …