3,250 research outputs found

    Knowledge discovery from mining the association between H5N1 outbreaks and environmental factors

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    The global spread of highly pathogenic avian influenza H5N1 in poultry, wild birds and humans, poses a significant panzootic threat and a serious public health risk. An efficient surveillance and disease control system requires a deep understanding of their spread mechanisms, including environmental factors responsible for the outbreak of the disease. Previous studies suggested that H5N1 viruses occurred under specific environmental circumstances in Asia and Africa. These studies were mainly derived from poultry outbreaks. In Europe, a large number of wild bird outbreaks were reported in west Europe with few or no poultry infections nearby. This distinct outbreak pattern in relation to environmental characteristics, however, has not yet been explored. This research demonstrated the use of logistic regression analyses to examine quantitative associations between anthropogenic and physical environmental factors, and the wild bird H5N1outbreaks in Europe. A geographic information system is used to visualize and analyze the data. Our results indicate that the H5N1 outbreaks occur in wild birds in Europe under predictable environmental conditions, which are highly correlated with increased NDVI in December, decreased aspect and slope, increased minimum temperature in October and decreased precipitation in January. It suggests that H5N1 outbreaks in wild birds are strongly influenced by food resource availability and facilitated by the increased temperature and the decreased precipitation. We therefore deduce that the H5N1 outbreaks in wild birds in Europe may be mainly caused by contact with wild birds. These findings are of great importance for global surveillance of H5N1 outbreaks in wild birds

    A normalized difference vegetation index (NDVI) time-series of idle agriculture lands: A preliminary study

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    In this paper, the NDVI time-series collected from the study area between year 2003 and 2005 of all land cover types are plotted and compared. The study area is the agricultural zones in Banphai District, Khonkean, Thailand. The LANDSAT satellite images of different dates were first transformed into a time series of Normalized Difference Vegetation Index (NDVI) images before the investigation. It can be visually observed that the NDVI time series of the Idle Agriculture Land (IAL) has the NDVI values closed to zero. In other words, the trend of the NDVI values remains, approximately, unchanged about the zero level for the whole period of the study time. In contrast, the non-idle areas hold a higher level of the NDVI variation. The NDVI values above 0.5 can be found in these non-idle areas during the growing seasons. Thus, it can be hypothesized that the NDVI time-series of the different land cover types can be used for IAL classification. This outcome is a prerequisite to the follow-up study of the NDVI pattern classification that will be done in the near future

    Environmental factors influencing the spread of the highly pathogenic avian influenza H5N1 virus in wild birds in Europe

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    A large number of occurrences of the highly pathogenic avian influenza (HPAI) H5N1 virus in wild birds were reported in Europe. The relationship between the occurrence pattern and environmental factors has, however, not yet been explored. This research uses logistic regression to quantify the relationships between anthropogenic or physical environmental factors and HPAI H5N1 occurrences. Our results indicate that HPAI H5N1 occurrences are highly correlated with the following: the increased normalized difference vegetation index (NDVI) in December; intermediate NDVI in March; lower elevations; increased minimum temperatures in January; and reduced precipitation in January. A predictive risk map of HPAI H5N1 occurrences in wild birds in Europe was generated on the basis of five key environmental factors. Independent validation of the risk map showed the predictive model to be of high accuracy (79%). The analysis suggests that HPAI H5N1 occurrences in wild birds are strongly influenced by the availability of food resources and are facilitated by increased temperatures and reduced precipitation. We therefore deduced that HPAI H5N1 occurrences in wild birds in Europe are probably caused by contact with other wild birds and not by contact with domestic poultry. These findings are important considerations for the global surveillance of HPAI H5N1 occurrences in wild birds

    Seizure outcome after switching antiepileptic drugs: A matched, prospective study.

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    OBJECTIVE: Outcomes after changing antiepileptic drugs (AEDs) have largely been studied in single cohort series. We recently reported the first study to examine this question in a controlled manner. Here we expand on these results by using a matched, prospective methodology applied to both uncontrolled and well-controlled patients taking any AED. METHODS: We reviewed all outpatient notes over a 9-month period and identified patients with focal epilepsy who were on monotherapy. We classified those who switched AEDs as case patients, with those remaining on the same drug serving as controls. We matched cases with controls for seizure status (seizure-free in the preceding 6 months or not), current AED, and number of failed AEDs. We subsequently assessed outcome 6 months later. RESULTS: Seizure-free patients who switched drug (n = 12) had a 16.7% rate of seizure recurrence at 6 months, compared to 2.8% among controls remaining on the same drug (n = 36, p = 0.11). There was a 37% remission rate among uncontrolled patients who switched drug compared to 55.6% among controls (n = 27 per group, p = 0.18). Uncontrolled patients who had previously tried more than one AED were somewhat less likely to enter remission (p = 0.057). Neither AED mechanism of action nor change in dosage impacted outcome. SIGNIFICANCE: Herein we provide further estimation of the modest risk (~14%) associated with switching AEDs in patients in remission compared to being maintained on the same regimen. Uncontrolled patients were no more likely to enter remission after a drug switch than they were after remaining on the same drug, suggesting that spontaneous changes in disease state, and not drug response, underlie remission in this population

    Turbulence and wind speed profiles for simulating the TMT AO performances

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    The site testing campaign of the Thirty Meter Telescope gathered an extensive amount of turbulence profiles. This data is modeled to describe the statistical characteristics of each site and act as "standard atmospheres" for use in AO simulations

    Long-term effect of antiepileptic drug switch on serum lipids and C-reactive protein.

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    BACKGROUND: Prior studies have shown that switching patients from inducing antiepileptic drugs (AEDs) to lamotrigine, levetiracetam, or topiramate reduces serum lipids and C-reactive protein (CRP). These studies were all of short duration, and some drugs, such as zonisamide, have not been investigated. METHODS: We recruited 41 patients taking phenytoin or carbamazepine who were being switched to zonisamide, lamotrigine, or levetiracetam. We measured serum lipids and CRP before the switch, \u3e6weeks after, and \u3e6months after. An untreated control group (n=14) underwent similar measurement. We combined these data with those of our previous investigation (n=34 patients and 16 controls) of a very similar design. RESULTS: There were no differences in outcome measures between the two inducing AEDs nor among the three noninducing AEDs. Total cholesterol (TC), atherogenic lipids, and CRP were higher under inducer treatment than in controls. All measures were elevated under inducer treatment relative to noninducer treatment, including TC (24mg/dL higher, 95% CI: 17.5-29.9, p CONCLUSIONS: We demonstrate that switching from inducing to noninducing AEDs produces an enduring reduction in serum lipids and CRP. These results provide further evidence that inducing AEDs may be associated with elevated vascular disease risk. These are the first vascular risk marker data in patients taking zonisamide, which shows a profile similar to that of other noninducing AEDs

    Discovery of 15-second oscillations in Hubble Space Telescope observations of WZ Sagittae following the 2001 outburst

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    We report the discovery of 15-s oscillations in ultraviolet observations of WZ Sge obtained with the Hubble Space Telescope approximately one month after the peak of the 2001 outburst. This is the earliest detection of oscillations in WZ Sge following an outburst and the first time that a signal near 15 s has been seen to be dominant. The oscillations are quite strong (amplitude about 5%), but not particularly coherent. In one instance, the oscillation period changed by 0.7 s between successive observations separated by less than 1 hour. We have also found evidence for weaker signals with periods near 6.5 s in some of our data. We discuss the implications of our results for the models that have been proposed to account for the 28-s oscillations seen in quiescence. If the periods of the 15-s oscillations can be identified with the periods of revolution of material rotating about the white dwarf, the mass of the white dwarf must satisfy M_WD > 0.71 M_sun. The corresponding limit for the 6.5-s signals is M_WD > 1.03 M_sun.Comment: accepted for publication in ApJ Letters; 13 pages, 4 postscript figures; new version corrects a few typos and matches version that will appear in ApJ

    Satellite-based modelling of potential tsetse (Glossina pallidipes) breeding and foraging sites using teneral and non-teneral fly occurrence data

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    BACKGROUND: African trypanosomiasis, which is mainly transmitted by tsetse flies (Glossina spp.), is a threat to public health and a significant hindrance to animal production. Tools that can reduce tsetse densities and interrupt disease transmission exist, but their large-scale deployment is limited by high implementation costs. This is in part limited by the absence of knowledge of breeding sites and dispersal data, and tools that can predict these in the absence of ground-truthing. METHODS: In Kenya, tsetse collections were carried out in 261 randomized points within Shimba Hills National Reserve (SHNR) and villages up to 5 km from the reserve boundary between 2017 and 2019. Considering their limited dispersal rate, we used in situ observations of newly emerged flies that had not had a blood meal (teneral) as a proxy for active breeding locations. We fitted commonly used species distribution models linking teneral and non-teneral tsetse presence with satellite-derived vegetation cover type fractions, greenness, temperature, and soil texture and moisture indices separately for the wet and dry season. Model performance was assessed with area under curve (AUC) statistics, while the maximum sum of sensitivity and specificity was used to classify suitable breeding or foraging sites. RESULTS: Glossina pallidipes flies were caught in 47% of the 261 traps, with teneral flies accounting for 37% of these traps. Fitted models were more accurate for the teneral flies (AUC = 0.83) as compared to the non-teneral (AUC = 0.73). The probability of teneral fly occurrence increased with woodland fractions but decreased with cropland fractions. During the wet season, the likelihood of teneral flies occurring decreased as silt content increased. Adult tsetse flies were less likely to be trapped in areas with average land surface temperatures below 24 °C. The models predicted that 63% of the potential tsetse breeding area was within the SHNR, but also indicated potential breeding pockets outside the reserve. CONCLUSION: Modelling tsetse occurrence data disaggregated by life stages with time series of satellite-derived variables enabled the spatial characterization of potential breeding and foraging sites for G. pallidipes. Our models provide insight into tsetse bionomics and aid in characterising tsetse infestations and thus prioritizing control areas. GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13071-021-05017-5
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