Towards European automatic bioaerosol monitoring: Comparison of 9 automatic pollen observational instruments with classic Hirst-type traps.

To benefit allergy patients and the medical practitioners, pollen information should be available in both a reliable and timely manner; the latter is only recently possible due to automatic monitoring. To evaluate the performance of all currently available automatic instruments, an international intercomparison campaign was jointly organised by the EUMETNET AutoPollen Programme and the ADOPT COST Action in Munich, Germany (March-July 2021). The automatic systems (hardware plus identification algorithms) were compared with manual Hirst-type traps. Measurements were aggregated into 3-hourly or daily values to allow comparison across all devices. We report results for total pollen as well as for Betula, Fraxinus, Poaceae, and Quercus, for all instruments that provided these data. The results for daily averages compared better with Hirst observations than the 3-hourly values. For total pollen, there was a considerable spread among systems, with some reaching R2 > 0.6 (3 h) and R2 > 0.75 (daily) compared with Hirst-type traps, whilst other systems were not suitable to sample total pollen efficiently (R2 < 0.3). For individual pollen types, results similar to the Hirst were frequently shown by a small group of systems. For Betula, almost all systems performed well (R2 > 0.75 for 9 systems for 3-hourly data). Results for Fraxinus and Quercus were not as good for most systems, while for Poaceae (with some exceptions), the performance was weakest. For all pollen types and for most measurement systems, false positive classifications were observed outside of the main pollen season. Different algorithms applied to the same device also showed different results, highlighting the importance of this aspect of the measurement system. Overall, given the 30 % error on daily concentrations that is currently accepted for Hirst-type traps, several automatic systems are currently capable of being used operationally to provide real-time observations at high temporal resolutions. They provide distinct advantages compared to the manual Hirst-type measurements.

Forecasting the seasonal pollen index by using a hidden Markov model combining meteorological and biological factors.

The seasonal pollen index (SPI) is a continuing concern within the fields of aerobiology, ecology, botany, and epidemiology. The SPI of anemophilous trees, which varies substantially from year to year, reflects the flowering intensity. This intensity is regulated by two factors: weather conditions during flower formation and the inner resource for assimilation. A deterministic approach has to date been employed for predicting SPI, in which the forecast is made entirely by parameters. However, given the complexity of the masting mechanism (which has intrinsic stochastic properties), few attempts have been made to apply a stochastic model that considers the inter-annual SPI variation as a stochastic process. We propose a hidden Markov model that can integrate the stochastic process of mast flowering and the meteorological conditions influencing flower formation to predict the annual birch pollen concentration. In experiments conducted, the model was trained and validated by using data in Hokkaido, Japan covering 22 years. In the model, the hidden Markov sequence was assigned to represent the recurrence of mast years via a transition matrix, and the observation sequences were designated as meteorological conditions in the previous summer, which are governed by hidden states with emission distribution. The proposed model achieved accuracies of 83.3% in the training period and 75.0% in the test period. Thus, the proposed model can provide an alternative perspective toward the SPI forecast and probabilistic information of pollen levels as a useful reference for allergy stakeholders.

Relationship between growth of facial morphology and chronologic age in preschool children with obstructive sleep apnea.

BACKGROUND: The purpose of this study was to evaluate the relationship between facial morphology using cephalometry and chronologic age in preschool children with obstructive sleep apnea (OSA). MATERIALS AND METHODS: From a group of lateral cephalometric radiographs taken of 35 children with OSA for diagnostic purposes, 15 were selected for the present investigation based on head position. The subjects consisted of preschool children with both OSA and primary dentition, all of them with a lowest documented SpO(2) <90% and a lowest 0

Three-dimensional prediction of maize pollen dispersal and cross-pollination, and the effects of windbreaks.

With the extensive adoption of transgenic crops, an understanding of transgene flow is essential to manage gene flow to non-GM crops. Thus, a flexible and accurate numerical model is required to assess gene flow through pollen dispersal. A three-dimensional atmospheric model combined with a diffusion transport model would be a useful tool for predicting pollen dispersal since it would be flexible enough to incorporate the effects of factors such as the spatial arrangement of crop combinations, land use, topography, windbreaks, and buildings. We applied such a model to field measurements of gene flow between two adjacent maize (Zea mays) cultivars, with suppression effects due to windbreaks, in an experimental cornfield in Japan. This combined model reproduced the measured cross-pollination distribution quite well in the case of maize plots with plant windbreaks slightly taller than the maize and without windbreaks, but the model underestimated the effect of a 6-m-tall windbreak net beyond 25 m from the donor pollen source on cross-pollination. The underestimation was most probably due to the problem of assimilated wind data. The model showed that the 6-m-tall windbreak and the plant wind break suppressed average cross-pollination rate by about 60% and 30%, respectively. Half-tall and coarser mesh windbreak net suppressed cross-pollination rates by 40% by reducing the swirl of donor pollen by reduced wind speed.

An algorithm for estimating potential deposition of corn pollen for environmental assessment.

The safety and impact on the environment of transgenic crops are important issues, and studies have shown that pollen from transgenic Bt (Bacillus thuringiensis) corn (Zea mays L.) may kill nontarget insects. To develop an algorithm for assessing the environmental effect of transgenic crops, we arranged a field experiment in Tsukuba, Japan. Pollen dispersal and deposition were measured inside and outside a cornfield throughout the flowering period. Weather conditions such as wind speed and direction were measured at the same time. Pollen dispersal peaked 1 week after the start of flowering and continued for 12 days thereafter. The variation in daily pollen dispersal was similar at all observation points. Both pollen dispersal and deposition decreased exponentially with distance from the cornfield on all days. We estimated potential pollen deposition with a quasi-mechanistic model that incorporates the effects of wind direction, wind speed, and flowering intensity. The daily potential deposition was summed over the flowering period, and then the relationship between distance from the cornfield and the integrated potential deposition was estimated. It was possible to show the effective area of the environmental risk zone posed by genetically modified pollen by combining the distance/deposition relationship with the dose/response relationship derived from a laboratory assay. The algorithm described here can be applied to various wind-pollinated plants to estimate both potential and integrated pollen deposition.

Absence of facial type differences among preschool children with sleep-related breathing disorder.

The aim of this study was to find out whether there are specific facial types and a specific hyoid bone position in preschool children with sleep-related breathing disorder (SBD). A total of 69 children were divided into 4 groups based on the mandibular line/Frankfurt horizontal angle and apnea index. There were 19 children with hyperdivergent facial type and SBD and 19 children with neutral facial type and SBD, all of them with documented 0 < AI < 5. Ten children had hyperdivergent facial type and non-SBD, and 21 children neutral facial type and non-SBD. The present findings show that SBD may be associated with both hyperdivergent and neutral facial type. Furthermore, we could not find any specific hyoid bone position related to SBD, non-SBD, or to facial type. In conclusion, it is important to note that while evaluation based on facial type (mandibular shape or position) does not necessarily distinguish between children with SBD and children without SBD (non-SBD), important differences are found in the pharynx. Short nasal floor length, long soft palate, and particularly short upper pharyngeal width can be considered indicators of SBD.

Sex-dependent differences in the craniofacial morphology of children with a sleep-related breathing disorder.

OBJECTIVE: The purpose of this article was to compare the craniofacial morphology and hyoid bone position of preschool girls and boys with sleep-related breathing disorder (SBD). STUDY DESIGN: The control groups consisted of girls and boys without ear, nose, and throat disorders. After lateral cephalometric radiographs were taken, the children were selected on the basis of the head position in relation to the true horizontal. Thirty-eight cephalometric variables were determined. RESULTS The findings indicate that boys with SBD had a larger anterior lower facial height and a more anterior hyoid bone position than girls with SBD. However, the distance between the third cervical vertebra and the hyoid bone was a constant value among girls and boys with SBD. Girls with SBD had a sagittally narrower pharyngeal airway space than boys with SBD. CONCLUSION: These findings suggest that boys with SBD have a skeletal risk factor, whereas girls with SBD have an airway risk factor. In conclusion, the difference in risk factors may have some bearing on the greater incidence of SBD in both boys and men.

Cephalometric evaluation of facial types in preschool children without sleep-related breathing disorder.

OBJECTIVE: this study was aimed at characterizing the craniofacial structures, i.e. the facial skeleton, cranial base, dentition, pharyngeal airway space, and the hyoid bone position, in healthy preschool children without sleep-related breathing disorder. MATERIALS AND METHODS: from lateral cephalometric radiographs taken of 92 children for diagnostic purposes, 45 were selected for the present investigation on the basis of head position, and divided according to the classification of Siriwat and Jarabak (Angle Orthod. 55 (1985) 127) into groups representing counter-clockwise (CC), straight downward (SD), and clockwise (C) facial types. RESULTS: the findings showed that, in comparison with the other groups, CC is associated with larger facial taper and posterior facial height, smaller mandibular line angle, ramus position, lower facial height and cranial base angle. By a similar comparison, C is associated with larger mandibular line, gonial angles and convexity, and with a smaller L-1 to mandibular line angle. There were no significant differences in hyoid bone position among the three groups. However, the distance of the lower pharynx was smaller in CC than in C, while the tongue base of CC was noted to be in a posterior position. CONCLUSIONS: thus, the results indicate that there are significant differences in the madibular position and form among the present three groups of children. It is proposed that the objective of vertical facial control ought to be included in the treatment of preschool children with malocclusion and respiratory disorder.