1,438 research outputs found

    Challenges and Benefits of Standardising Early Warning Systems: A Case Study of New Zealand’s Volcanic Alert Level System

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    Volcano early warning systems are used globally to communicate volcano-related information to diverse stakeholders ranging from specific user groups to the general public, or both. Within the framework of a volcano early warning system, Volcano Alert Level (VAL) systems are commonly used as a simple communication tool to inform society about the status of activity at a specific volcano. Establishing a VAL system that is effective for multiple volcanoes can be challenging, given that each volcano has specific behavioural characteristics. New Zealand has a wide range of volcano types and geological settings, including rhyolitic calderas capable of very large eruptions (>500 km3) and frequent unrest episodes, explosive andesitic stratovolcanoes, and effusive basaltic eruptions at both caldera and volcanic field settings. There is also a range in eruption frequency, requiring the VAL system to be used for both frequently active ‘open-vent’ volcanoes, and reawakening ‘closed-vent’ volcanoes. Furthermore, New Zealand’s volcanoes are situated in a variety of risk settings ranging from the Auckland Volcanic Field, which lies beneath a city of 1.4 million people; to Mt. Ruapehu, the location of popular ski fields that are occasionally impacted by ballistics and lahars, and produces tephra that falls in distant cities. These wide-ranging characteristics and their impact on society provide opportunities to learn from New Zealand’s experience with VAL systems, and the adoption of a standardised single VAL system for all of New Zealand’s volcanoes following a review in 2014. This chapter outlines the results of qualitative research conducted in 2010–2014 with key stakeholders and scientists, including from the volcano observatory at GNS Science, to ensure that the resulting standardised VAL system is an effective communication tool. A number of difficulties were faced in revising the VAL system so that it remains effective for all of the volcanic settings that exist in New Zealand. If warning products are standardised too much, end-user decision making and action can be limited when unusual situations occur, e.g., there may be loss of specific relevance in the alert message. Specific decision-making should be based on more specific parameters than the VAL alone, however wider VAL system standardisation can increase credibility, a known requirement for effective warning, by ensuring that warning sources are clear, trusted and widely understood. With a credible source, user groups are less likely to look for alternatives or confirmation, leading to faster action. Here we consider volcanic warnings within the wider concept of end-to-end multi-hazard early warning systems including detection, evaluation, notification, decision-making and action elements (based on Carsell et al. 2004)

    Human RioK3 is a novel component of cytoplasmic pre-40S pre-ribosomal particles

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    Maturation of the 40S ribosomal subunit precursors in mammals mobilizes several non-ribosomal proteins, including the atypical protein kinase RioK2. Here, we have investigated the involvement of another member of the RIO kinase family, RioK3, in human ribosome biogenesis. RioK3 is a cytoplasmic protein that does not seem to shuttle between nucleus and cytoplasm via a Crm1-dependent mechanism as does RioK2 and which sediments with cytoplasmic 40S ribosomal particles in a sucrose gradient. When the small ribosomal subunit biogenesis is impaired by depletion of either rpS15, rpS19 or RioK2, a concomitant decrease in the amount of RioK3 is observed. Surprisingly, we observed a dramatic and specific increase in the levels of RioK3 when the biogenesis of the large ribosomal subunit is impaired. A fraction of RioK3 is associated with the non ribosomal pre-40S particle components hLtv1 and hEnp1 as well as with the 18S-E pre-rRNA indicating that it belongs to a bona fide cytoplasmic pre-40S particle. Finally, RioK3 depletion leads to an increase in the levels of the 21S rRNA precursor in the 18S rRNA production pathway. Altogether, our results strongly suggest that RioK3 is a novel cytoplasmic component of pre-40S pre-ribosomal particle(s) in human cells, required for normal processing of the 21S pre-rRNA

    Wave attenuation at a salt marsh margin: A case study of an exposed coast on the Yangtze estuary

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    To quantify wave attenuation by (introduced) Spartina alterniflora vegetation at an exposed macrotidal coast in the Yangtze Estuary, China, wave parameters and water depth were measured during 13 consecutive tides at nine locations ranging from 10 m seaward to 50 m landward of the low marsh edge. During this period, the incident wave height ranged from <0.1 to 1.5 m, the maximum of which is much higher than observed in other marsh areas around the world. Our measurements and calculations showed that the wave attenuation rate per unit distance was 1 to 2 magnitudes higher over the marsh than over an adjacent mudflat. Although the elevation gradient of the marsh margin was significantly higher than that of the adjacent mudflat, more than 80% of wave attenuation was ascribed to the presence of vegetation, suggesting that shoaling effects were of minor importance. On average, waves reaching the marsh were eliminated over a distance of similar to 80 m, although a marsh distance of >= 100 m was needed before the maximum height waves were fully attenuated during high tides. These attenuation distances were longer than those previously found in American salt marshes, mainly due to the macrotidal and exposed conditions at the present site. The ratio of water depth to plant height showed an inverse correlation with wave attenuation rate, indicating that plant height is a crucial factor determining the efficiency of wave attenuation. Consequently, the tall shoots of the introduced S. alterniflora makes this species much more efficient at attenuating waves than the shorter, native pioneer species in the Yangtze Estuary, and should therefore be considered as a factor in coastal management during the present era of sea-level rise and global change. We also found that wave attenuation across the salt marsh can be predicted using published models when a suitable coefficient is incorporated to account for drag, which varies in place and time due to differences in plant characteristics and abiotic conditions (i.e., bed gradient, initial water depth, and wave action).

    Creation of a multiple-use recombinant inbred line population for the development of molecular markers in soft white winter wheat

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    Tese de doutoramento em Física (Pré-Bolonha), especialidade de Física Experimental, apresentada à Faculdade de Ciências e Tecnologia da Universidade de CoimbraPositron emission tomography based on resistive plate chambers (RPC-PET) has been proposed for both preclinical and clinical applications. We firstly present imaging results of needle-like and planar 22Na sources obtained with a prototype of a high-acceptance small-animal RPC-PET. The two detector modules utilized in this experiment had an effective front face of 6.4 x 6.4 cm^2 and consisted of 5 gas gaps and 6 glass electrodes with a total thickness of 5 mm. The data included lines of response (LORs) inclined up to 58º, and the depth of interaction (DOI) was accurately measured, demonstrating the parallax-free property inherent to RPC-PET. The maximum likelihood expectation-maximization (MLEM) reconstruction of the acquired data yielded an excellent and stable resolution of 0.4 mm full width at half maximum (FWHM). Concurrently, we pursued studies of a suggested whole-body single-bed RPC-PET. It has been shown by simulation that RPC-PET with an axial field-of-view (AFOV) of 2.4 m is feasible and yields an absolute sensitivity at least one order of magnitude superior to that of typical crystal-based PET scanners. In addition, RPC-PET offers an important time-of-flight (TOF) advantage and provides a potentially very-high spatial resolution at the detector level. In the second part of this work, a fully three-dimensional reconstruction algorithm capable of processing the very inclined LORs from large AFOV systems such as RPC-PET is demonstrated. It relies on the application of a TOF-based-kernel into the MLEM algorithm. With the 300 ps FWHM time resolution, already experimentally demonstrated, a rejection of 63% of the body-scattered events is obtained. We present reconstructed results from blind simulations corresponding to the anthropomorphic phantom, NCAT, with oncological lesions introduced into different locations within the human body. A comparison between 300 and 600 ps FWHM TOF reconstructed images is performed, with an increasing detectability being observed for a better TOF resolution. We finally compare issues related to image convergence speed. An alternative new approach, which consists in dividing the full-body data into nine different image regions that are reconstructed independently with graphical processing unit (GPU) assistance, provides a six times faster reconstruction compared with a GPU-based whole-body reconstruction. For a 300 ps FWHM RPC-PET scanner, this allows reaching a reconstructed image, that results from 1.6 x 10^10 annihilations within 7 minutes and upon injection of 2 mCi, just 4 minutes after the end of data acquisition. We conclude that RPC-PET is well oriented to compete with other commercial PET scanners in the global market.A tomografia por emissão de positrões baseada em detectores do tipo câmaras de placas resistivas (RPC-PET) foi proposta para aplicação em ensaios com pequenos animais e na prática clínica. Neste trabalho, apresentamos primeiramente resultados experimentais obtidos a partir de um protótipo RPC-PET de alta aceitação para pequenos animais. Foram obtidas imagens de fontes do radioisótopo 22Na, uma quase pontual e outra planar. Usámos dois módulos de detectores RPC com uma área activa de 6.4 x 6.4 cm^2 e uma espessura de 5 mm, constituída por 6 vidros empilhados e 5 espaços gasosos definidos entre eles. Os dados adquiridos incluíram linhas de coincidência (LORs) inclinadas até um ângulo de 58º, tornando essencial a medida precisa da profundidade de interacção. A identificação dos espaços gasosos onde ocorreram as avalanches permitiu demonstrar a ausência de erro de paralaxe nas medidas realizadas com o RPC-PET para pequenos animais. A partir da reconstrução dos dados processados com o algoritmo maximum likelihood expectation-maximization (MLEM), obtivemos uma resolução espacial com largura a meia altura (FWHM) de 0.4 mm, excelente e estável. Em paralelo, continuámos a estudar as potencialidades de um protótipo RPC-PET de corpo inteiro e cama única, orientado para pessoas. Já foi anteriormente demonstrado por simulação que um scanner RPC-PET com 2.4 m de campo de visão axial (AFOV) é viável e permitirá o aumento de sensibilidade de pelo menos uma ordem de grandeza em relação aos scanners PET com cristais. Duas outras virtudes do RPC-PET são a sua capacidade de medição do tempo de voo (TOF) dos fotões e a elevada resolução espacial ao nível do detector. Na segunda parte deste trabalho apresentamos um algoritmo de reconstrução, totalmente tridimensional, capaz de processar LORs muito inclinadas em sistemas com um AFOV longo, como é o caso do RPC-PET. Este algoritmo acrescenta um kernel ao algoritmo MLEM, baseado na informação de TOF. Com uma resolução temporal de 300 ps FWHM, já experimentalmente comprovada, é possível rejeitar 63% dos eventos dispersados no corpo humano. Exibimos imagens reconstruídas obtidas a partir de simulações do fantoma antropomórfico, NCAT, com lesões oncológicas situadas em diferentes locais do corpo humano. A comparação entre imagens conseguidas com resoluções temporais de 300 ps e 600 ps FWHM, permite observar uma detectabilidade acrescida associada à melhor resolução de TOF. Por último, são estudados os tempos de convergência da reconstrução. Um método inovador e alternativo, que consiste na divisão dos dados do corpo humano em nove regiões e na reconstrução independente desses dados com recurso a unidades de processamento gráfico (GPUs), permite uma reconstrução seis vezes mais rápida do que a reconstrução de corpo inteiro também com o auxílio de GPUs. A partir de dados de 1.6 x 10^10 aniquilações ocorridas durante uma aquisição de 7 minutos e para uma actividade injectada de 2 mCi, um scanner RPC-PET com uma resolução temporal de 300 ps FWHM permitirá obter uma imagem reconstruída apenas 4 minutos após o fim da aquisição. Podemos assim concluir que o RPC-PET está bem colocado para competir no mercado dos scanners PET comerciais

    Routine serum biomarkers, but not dual-energy X-ray absorptiometry, correlate with cortical bone mineral density in children and young adults with chronic kidney disease

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    BACKGROUND: Biomarkers and dual-energy X-ray absorptiometry (DXA) are thought to be poor predictors of bone mineral density (BMD). The Kidney Disease: Improving Global Outcomes guidelines suggest using DXA if the results will affect patient management, but this has not been studied in children or young adults in whom bone mineral accretion continues to 30 years of age. We studied the clinical utility of DXA and serum biomarkers against tibial cortical BMD (CortBMD) measured by peripheral quantitative computed tomography, expressed as Z-score CortBMD, which predicts fracture risk. METHODS: This was a cross-sectional multicentre study in 26 patients with CKD4 and 5 and 77 on dialysis. RESULTS: Significant bone pain that hindered activities of daily living was present in 58%, and 10% had at least one low-trauma fracture. CortBMD and cortical mineral content Z-scores were lower in dialysis compared with CKD patients (P = 0.004 and P = 0.02). DXA BMD hip and lumbar spine Z-scores did not correlate with CortBMD or biomarkers. CortBMD was negatively associated with parathyroid hormone (PTH; r = -0.44, P < 0.0001) and alkaline phosphatase (ALP; r = -0.22, P = 0.03) and positively with calcium (Ca; r = 0.33, P = 0.001). At PTH <3 times upper limit of normal, none of the patients had a CortBMD below -2 SD (odds ratio 95% confidence interval 7.331 to infinity). On multivariable linear regression PTH (β = -0.43 , P < 0.0001), ALP (β = -0.36, P < 0.0001) and Ca (β = 0.21, P = 0.005) together predicted 57% of variability in CortBMD. DXA measures did not improve this model. CONCLUSIONS: Taken together, routinely used biomarkers, PTH, ALP and Ca, but not DXA, are moderate predictors of cortical BMD. DXA is not clinically useful and should not be routinely performed in children and young adults with CKD 4-5D

    Bone Mineral Density and Vascular Calcification in Children and Young Adults With CKD 4 to 5 or on Dialysis

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    Introduction: Older adults with chronic kidney disease (CKD) can have low bone mineral density (BMD) with concurrent vascular calcification. Mineral accrual by the growing skeleton may protect young people with CKD from extraosseous calcification. Our hypothesis was that children and young adults with increasing BMD do not develop vascular calcification. Methods: This was a multicenter longitudinal study in children and young people (5–30 years) with CKD stages 4 to 5 or on dialysis. BMD was assessed by tibial peripheral quantitative computed tomography (pQCT) and lumbar spine dual-energy X-ray absorptiometry (DXA). The following cardiovascular imaging tests were undertaken: cardiac computed tomography for coronary artery calcification (CAC), ultrasound for carotid intima media thickness z-score (cIMTz), pulse wave velocity z-score (PWVz), and carotid distensibility for arterial stiffness. All measures are presented as age-adjusted and sex-adjusted z-scores. Results: One hundred participants (median age 13.82 years) were assessed at baseline and 57 followed up after a median of 1.45 years. Trabecular BMD z-score (TrabBMDz) decreased (P = 0.01), and there was a nonsignificant decrease in cortical BMD z-score (CortBMDz) (P = 0.09). Median cIMTz and PWVz showed nonsignificant increase (P = 0.23 and P = 0.19, respectively). The annualized increase in TrabBMDz (ΔTrabBMDz) was an independent predictor of cIMTz increase (R2 = 0.48, β = 0.40, P = 0.03). Young people who demonstrated statural growth (n = 33) had lower ΔTrabBMDz and also attenuated vascular changes compared with those with static growth (n = 24). Conclusion: This hypothesis-generating study suggests that children and young adults with CKD or on dialysis may develop vascular calcification even as their BMD increases. A presumed buffering capacity of the growing skeleton may offer some protection against extraosseous calcification

    The association between histamine 2 receptor antagonist use and Clostridium difficile infection: a systematic review and meta-analysis.

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    Background Clostridium difficile infection (CDI) is a major health problem. Epidemiological evidence suggests that there is an association between acid suppression therapy and development of CDI. Purpose We sought to systematically review the literature that examined the association between histamine 2 receptor antagonists (H2RAs) and CDI. Data source We searched Medline, Current Contents, Embase, ISI Web of Science and Elsevier Scopus from 1990 to 2012 for all analytical studies that examined the association between H2RAs and CDI. Study selection Two authors independently reviewed the studies for eligibility. Data extraction Data about studies characteristics, adjusted effect estimates and quality were extracted. Data synthesis Thirty-five observations from 33 eligible studies that included 201834 participants were analyzed. Studies were performed in 6 countries and nine of them were multicenter. Most studies did not specify the type or duration of H2RAs therapy. The pooled effect estimate was 1.44, 95% CI (1.22–1.7), I2 = 70.5%. This association was consistent across different subgroups (by study design and country) and there was no evidence of publication bias. The pooled effect estimate for high quality studies was 1.39 (1.15–1.68), I2 = 72.3%. Meta-regression analysis of 10 study-level variables did not identify sources of heterogeneity. In a speculative analysis, the number needed to harm (NNH) with H2RAs at 14 days after hospital admission in patients receiving antibiotics or not was 58, 95% CI (37, 115) and 425, 95% CI (267, 848), respectively. For the general population, the NNH at 1 year was 4549, 95% CI (2860, 9097). Conclusion In this rigorous systematic review and meta-analysis, we observed an association between H2RAs and CDI. The absolute risk of CDI associated with H2RAs is highest in hospitalized patients receiving antibiotics
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