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736 result(s) for "scan time"
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Sociodemographic and spatiotemporal profiles of hepatitis-A in the state of Pará, Brazil, based on reported notified cases
Hepatitis-A virus is a worldwide healthcare problem, mainly affecting countries with poor sanitary and socioeconomic conditions. This communication evaluates the spatiotemporal variability of the disease’s socioepidemiological profile in one of the endemic Brazilian regions (Pará State) prior to (2008-2013) and after (2014-2017) the launch of the national public vaccination programme. Hepatitis-A epidemiological reports concerning Pará State - Brazil - were used for this study including municipalitylevel data of the disease’s reported positive notification cases (PNCs). The analyses involved socioepidemiological profiling and space-time scan statistics. A total of 5500 PNCs were reported in the study period. On average, PNCs decreased over time throughout the state, with strongest drops after 2015. The PNCs were specific for gender, race/ethnic origin and age group. The predominant gender and race/ethnic groups was male and brown, respectively. While children were the most susceptible age group prior to 2015, there was a shift towards older ages (young and adults) in later years. Those found to be the most affected by the disease, as shown by space-time scan statistics, were people in densely populated municipalities with unsatisfactory sanitary conditions and also less well covered by the public vaccination programme. Despite drops in the number of hepatitis-A PNCs, thanks to the national vaccination programme, the disease still persists in Pará State and elsewhere in Brazil. The present study reinforces the need of continuous prevention and control strategies for effective control and erradication of hepatitis-A.
Technical note: Partitioning of gated single photon emission computed tomography raw data for protocols optimization
Purpose Methodologies for optimization of SPECT image acquisition can be challenging due to imaging throughput, physiological bias, and patient comfort constraints. We evaluated a vendor‐independent method for simulating lower count image acquisitions. Methods We developed an algorithm that recombines the ECG‐gated raw data into reduced counting acquisitions. We then tested the algorithm to simulate reduction of counting statistics from phantom SPECT image acquisition, which was synchronized with an ECG simulator. The datasets were reconstructed with a resolution recovery algorithm and the summed stress score (SSS) was assessed by three readers (two experts and one automatic). Results The algorithm generated varying counting levels, simulating multiple examinations at the same time. The error between the expected and the simulated countings ranged from approximately 5% to 10% for the ungated simulations and 0% for the gated simulations. Conclusions The vendor‐independent algorithm successfully generated lower counting statistics datasets from single‐gated SPECT raw data. This method can be readily implemented for optimal SPECT research aiming to lower the injected activity and/ or to shorten the acquisition time.
Spatio-temporal patterns of dengue in Malaysia: combining address and sub-district level
Spatio-temporal patterns of dengue risk in Malaysia were studied both at the address and the sub-district level in the province of Selangor and the Federal Territory of Kuala Lumpur. We geocoded laboratory-confirmed dengue cases from the years 2008 to 2010 at the address level and further aggregated the cases in proportion to the population at risk at the sub-district level. Kulldorff's spatial scan statistic was applied for the investigation that identified changing spatial patterns of dengue cases at both levels. At the address level, spatio-temporal clusters of dengue cases were concentrated at the central and south-eastern part of the study area in the early part of the years studied. Analyses at the sub-district level revealed a consistent spatial clustering of a high number of cases proportional to the population at risk. Linking both levels assisted in the identification of differences and confirmed the presence of areas at high risk for dengue infection. Our results suggest that the observed dengue cases had both a spatial and a temporal epidemiological component, which needs to be acknowledged and addressed to develop efficient control measures, including spatially explicit vector control. Our findings highlight the importance of detailed geographical analysis of disease cases in heterogeneous environments with a focus on clustered populations at different spatial and temporal scales. We conclude that bringing together information on the spatio-temporal distribution of dengue cases with a deeper insight of linkages between dengue risk, climate factors and land use constitutes an important step towards the development of an effective risk management strategy.
Optimisation of the I–V measurement scan time through dynamic modelling of solar cells
High-performance solar cells and photovoltaic modules exhibit high internal capacitance, limiting the speed of their transient responses including the current–voltage characteristics scans. This study proffers a model-based method to obtain optimal scan time during the current–voltage performance characterisation of a solar cell or module while preserving a pre-set accuracy. Static model parameters are extracted from the quasi-static current–voltage characteristic, whereas the capacitive character, modelled by two bias voltage dependent capacitances, is determined from the open-circuit voltage decay measurement. The obtained model is used to calculate the optimal current–voltage curve scan time. Efficacy of the proposed method is demonstrated through test results obtained on three wafer-based solar cells. I–V curve errors determined by the proposed method at different scan times are in good agreement with the measurements. Results show that in order to achieve < 0.5% error in curve fitting, determined scan times of tested crystalline silicon solar cells lie within the range of 3.6–45 ms for constant angle step semiconductor curve tracer. Use of a capacitive-based curve tracer, however, requires approximately twice that time to retain a comparable error.
Accuracy of intraoral scanning in completely and partially edentulous maxillary and mandibular jaws: an in vitro analysis
Objectives New generation intraoral scanners are promoted to be suitable for digital scans of long-span edentulous spaces and completely edentulous arches; however, the evidence is lacking. The current study evaluated the accuracy of intraoral scanning (IOS) in partially and completely edentulous arch models and analyzed the influence of operator experience on accuracy. Materials and methods Four different resin models (completely and partially edentulous maxilla and mandible) were scanned, using a new generation IOS device ( n = 20 each). Ten scans of each model were performed by an IOS-experienced and an inexperienced operator. An industrial high-precision scanner was employed to obtain reference scans. IOS files of each model-operator combination, their respective reference scan files ( n = 10 each; total = 80), as well as the IOS files from each model generated by the same operator, were superimposed ( n = 45; total = 360) to calculate trueness and precision. An ANOVA for mixed models and post hoc t tests for mixed models were used to assess group-wise differences (α = 0.05). Results The median overall trueness and precision were 24.2 μm (IQR 20.7–27.4 μm) and 18.3 μm (IQR 14.4–22.1 μm), respectively. The scans of the inexperienced operator had significantly higher trueness in the edentulous mandibular model ( p = 0.0001) and higher precision in the edentulous maxillary model ( p = 0.0004). Conclusion The accuracy of IOS for partially and completely edentulous arches in in vitro settings was high. Experience with IOS had small influence on the accuracy of the scans. Clinical relevance IOS with the tested new generation intraoral scanner may be suitable for the fabrication of removable dentures regardless of clinician’s experience in IOS.
Species-specific spatiotemporal patterns of leopard, lion and tiger attacks on humans
1. Large carnivores of the genus Panthera can pose serious threats to public safety. Although the annual number of attacks on humans is rare compared to livestock depredation, such incidents undermine popular support for wildlife conservation and require immediate responses to protect human life. 2. We used a space–time scan method to perform a novel spatiotemporal analysis of 908 attacks on humans by lions, leopards, and tigers to estimate the risks of further attacks in the same locales. 3. We found that a substantial proportion of attacks were clustered in time and space, but the dimension of these outbreaks varied between species. Lion outbreaks included more human fatalities, persisted for longer periods of time, and extended over larger areas than tiger or leopard outbreaks. 4. Synthesis and applications. Our analysis reveals the typical spatiotemporal patterns of past lion, leopard, and tiger attacks on humans. In future, this technique could be used by relevant agencies to warn local people of risks from further attacks within a certain time and distance following an initial incident by each species. Furthermore, the approach can help identify areas requiring management interventions to address such threats. anthropogenic landscape, attacks on humans, big cats, human–wildlife conflict, Panthera,space–time scan, spatiotemporal clustering
Fire protection priorities in the oak forests of Iran with an emphasis on vertebrate habitat preservation
This study examines the impact of fire incidents on wildlife and habitats in the western oak forests of Iran (Zagros region). These forests are globally recognized for their exceptional biodiversity but are frequently threatened by wildfires. To achieve this, the study uses the space–time scan statistics permutation (STSSP) model to identify areas with a higher frequency of fires. The study also analyzes the effects of fires on the Zagros forests from 2000 to 2021 using remote-sensing MODIS data. Also, to understand the elements at risk of fire, burned areas were assessed based on the richness of vertebrate species, determined by the distribution of 88 vertebrate species. The results show that the annual fire rate in the Zagros forests is 76.2 (fire occurrences per year), calculated using the Poisson distribution. Findings show the highest fire rates are found in the northwest and a part of the south of the Zagros. The northwest of the Zagros also has the largest number of single fires and clusters, indicating a wide spatial distribution of fire in these regions. On the other side, it was unexpectedly found that these regions have the richest number of species and higher habitat value. The results demonstrate a significant correlation between the value of the habitat and the extent of burned areas (p < 0.05). The study also reveals that the greatest impact of fires is on small vertebrates. The overlap of frequent fire spots with the richest regions of Zagros oak forests in terms of vertebrate diversity emphasizes the need for strategic forest risk reduction planning, especially in these priority zones.
Women’s cancers in China: a spatio-temporal epidemiology analysis
Background Women's cancers, represented by breast and gynecologic cancers, are emerging as a significant threat to women's health, while previous studies paid little attention to the spatial distribution of women's cancers. This study aims to conduct a spatio-temporal epidemiology analysis on breast, cervical and ovarian cancers in China, thus visualizing and comparing their epidemiologic trends and spatio-temporal changing patterns. Methods Data on the incidence and mortality of women’s cancers between January 2010 and December 2015 were obtained from the National Cancer Registry Annual Report. Linear tests and bar charts were used to visualize and compare the epidemiologic trends. Two complementary spatial statistics (Moran’s I statistics and Kulldorff’s space–time scan statistics) were adopted to identify the spatial–temporal clusters. Results The results showed that the incidence and mortality of breast cancer displayed slow upward trends, while that of cervical cancer increase dramatically, and the mortality of ovarian cancer also showed a fast increasing trend. Significant differences were detected in incidence and mortality of breast, cervical and ovarian cancer across east, central and west China. The average incidence of breast cancer displayed a high-high cluster feature in part of north and east China, and the opposite traits occurred in southwest China. In the meantime, the average incidence and mortality of cervical cancer in central China revealed a high-high cluster feature, and that of ovarian cancer in northern China displayed a high-high cluster feature. Besides, the anomalous clusters were also detected based on the space–time scan statistics. Conclusion Regional differences were detected in the distribution of women’s cancers in China. An effective response requires a package of coordinated actions that vary across localities regarding the spatio-temporal epidemics and local conditions.
Assessment of the Effect of Soil Sample Preparation, Water Content and Excitation Time on Proximal X-ray Fluorescence Sensing
X-ray fluorescence (XRF) spectroscopy offers a fast and efficient method for analysing soil elemental composition, both in the laboratory and the field. However, the technique is sensitive to spectral interference as well as physical and chemical matrix effects, which can reduce the precision of the measurements. We systematically assessed the XRF technique under different sample preparations, water contents, and excitation times. Four different soil samples were used as blocks in a three-way factorial experiment, with three sample preparations (natural aggregates, ground to ≤2 mm and ≤1 mm), three gravimetric water contents (air-dry, 10% and 20%), and three excitation times (15, 30 and 60 s). The XRF spectra were recorded and gave 540 spectra in all. Elemental peaks for Si, K, Ca, Ti, Fe and Cu were identified for analysis. We used analysis of variance (anova) with post hoc tests to identify significant differences between our factors and used the intensity and area of the elemental peaks as the response. Our results indicate that all of these factors significantly affect the XRF spectrum, but longer excitation times appear to be more defined. In most cases, no significant difference was found between air-dry and 10% water content. Moisture has no apparent effect on coarse samples unless ground to 1 mm. We suggested that the XRF measurements that take 60 s from dry samples or only slightly moist ones might be an optimum option under field conditions.
Modeling mumps incidence in China: spatiotemporal clusters and evolving risk factors (2005–2020)
Background Mumps remains a major public health challenge in China, exhibiting distinct seasonal peaks in spring and notable spatial heterogeneity in incidence patterns. These spatiotemporal characteristics necessitate advanced analytical methods to identify driving factors and inform targeted intervention strategies. Methods We integrated space-time scanning statistics and geographically and temporally weighted regression (GTWR) to analyze mumps incidence across China (2005–2020). This approach overcomes the limitations of traditional methods by simultaneously assessing economic development, education level, population structure, and healthcare resources factors. Results National incidence exhibited a fluctuating decline from 27.60 (2005) to 10.09 per 100,000 (2020), peaking in 2012 (38.49 per 100,000). Space-time scanning identified persistent high-risk clusters in western China and transient clusters in northeastern regions. GTWR modeling revealed significant spatiotemporal variations in risk factors: illiteracy rate and population density showed transitioning impacts reflecting improved health education, while household size effects strengthened, emphasizing close-contact transmission. Healthcare resources exhibited opposing effects, being protective in eastern regions but risk-enhancing in western areas. GDP per capita demonstrated protective effects in western and southeastern China but was associated with elevated risk elsewhere. Conclusions The findings underscore the need for regionally tailored prevention strategies and precision interventions accounting for local socioeconomic contexts. This study provides a methodological framework for spatiotemporal disease surveillance and evidence-based policy-making to reduce mumps transmission in China.