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Formation of new aerosol particles by nucleation and growth is a significant source of aerosols in the atmosphere. New particle formation events usually take place during daytime, but in some locations they have been observed also at night. In the present study we have combined chamber experiments, quantum chemical calculations and aerosol dynamics models to study nocturnal new particle formation. All our approaches demonstrate, in a consistent manner, that the oxidation products of monoterpenes play an important role in nocturnal nucleation events. By varying the conditions in our chamber experiments, we were able to reproduce the very different types of nocturnal events observed earlier in the atmosphere. The exact strength, duration and shape of the events appears to be sensitive to the type and concentration of reacting monoterpenes, as well as the extent to which the monoterpenes are exposed to ozone and potentially other atmospheric oxidants.

The influence of biogenic particle formation on climate is a well recognised phenomenon. To understand the mechanisms underlying the biogenic particle formation, determining the chemical composition of the new particles and therefore the species that drive the particle production is of utmost importance. Due to the very small amount of mass involved, indirect approaches are frequently used to infer the composition. We present here the results of such an indirect approach by simultaneously measuring volatile and hygroscopic properties of newly formed particles in a forest environment. It is shown that the particles are composed of both sulphates and organics, with the amount of sulphate component strongly depending on the available gas-phase sulphuric acid, and the organic components having the same volatility and hygroscopicity as photo-oxidation products of a monoterpene such as α-pinene. Our findings agree with a two-step process through nucleation and cluster formation followed by simultaneous growth by condensation of sulphates and organics that take the particles to climatically relevant sizes.

The world's forests produce atmospheric aerosol by emitting volatile organic compounds (VOC) which, after being oxidized in the atmosphere, readily condense on the omnipresent nanometer-sized nuclei and grow them to climatically relevant sizes. The cooling effect of aerosols is the greatest uncertainty in current climate models and estimates of radiative forcing. Therefore, identifying the environmental factors influencing the biogenic formation of aerosols is crucial. In this paper, we connected biogenic aerosol formation events observed in a Eucalypt forest in South-East Australia during July 2005–December 2006 to air mass history using 96-h back trajectories. Formation of new particles was most frequent in the dry westerly and south-westerly air masses. According to NDVI (Normalized Difference Vegetation Index) measurements, photosynthesis was not significantly higher in this direction compared to the north-east direction. It is unlikely, therefore, that differences in photosynthesis-derived organic precursor emissions would have been significant enough to lead to the clear difference in NPF frequency between these two directions. Instead, the high evaporation rates above the Pacific Ocean resulted in humid winds from the north-east that effectively suppressed new-particle formation in the forest hundreds of kilometers inland. No other factor varied as significantly in tune with new-particle formation as humidity and we concluded that, in addition to local meteorological factors in the forest, the magnitude of evaporation from oceans hundreds of kilometers upwind can effectively suppress or enhance new-particle formation. Our findings indicate that, unlike warm waters, the cold polar oceans provide excellent clean and dry background air that enhances aerosol formation above near-coastal forests in Fennoscandia and South-East Australia.

A month-long intensive measurement campaign was conducted in March/April 2007 at Agnes Water, a remote coastal site just south of the Great Barrier Reef on the east coast of Australia. Particle and ion size distributions were continuously measured during the campaign. Coastal nucleation events were observed in clean, marine air masses coming from the south-east on 65% of the days. The events usually began at ~10:00 local time and lasted for 1–4 h. They were characterised by the appearance of a nucleation mode with a peak diameter of ~10 nm. The freshly nucleated particles grew within 1–4 h up to sizes of 20–50 nm. The events occurred when solar intensity was high (~1000 W m−2) and RH was low (~60%). Interestingly, the events were not related to tide height. The volatile and hygroscopic properties of freshly nucleated particles (17–22.5 nm), simultaneously measured with a volatility-hygroscopicity-tandem differential mobility analyser (VH-TDMA), were used to infer chemical composition. The majority of the volume of these particles was attributed to internally mixed sulphate and organic components. After ruling out coagulation as a source of significant particle growth, we conclude that the condensation of sulphate and/or organic vapours was most likely responsible for driving particle growth at sizes greater than 10 nm during the nucleation events. Although there was a possibility that the precursor vapours responsible for particle formation and growth had continental sources, on the balance of available data we would suggest that the precursors were most likely of marine/coastal origin. Furthermore, a unique and particularly strong nucleation event was observed during northerly wind. The event began early one morning (08:00) and lasted almost the entire day resulting in the production of a large number of ~80 nm particles (average modal concentration during the event was 3200 cm−3). The Great Barrier Reef was the most likely source of precursor vapours responsible for this event.

Biogenic aerosol formation is likely to contribute significantly to the global aerosol load. In recent years, new-particle formation has been observed in various ecosystems around the world but hardly any measurements have taken place in the terrestrial Southern Hemisphere. Here, we report the first results of atmospheric ion and charged particle concentrations as well as of new-particle formation in a Eucalypt forest in Tumbarumba, South-East Australia, from July 2005 to October 2006. The measurements were carried out with an Air Ion Spectrometer (AIS) with a size range from 0.34 to 40 nm. The Eucalypt forest was a very strong source of new aerosol particles. Daytime aerosol formation took place on 52% of days with acceptable data, which is 2–3 times as often as in the Nordic boreal zone. Average growth rates for negative/positive 1.5–3 nm particles during these formation events were 2.89/2.68 nmh−1, respectively; for 3-7 nm particles 4.26/4.03, and for 7–20 nm particles 8.90/7.58 nmh−1, respectively. The growth rates for large ions were highest when the air was coming from the native forest which suggests that the Eucalypts were a strong source of condensable vapours. Average concentrations of cluster ions (0.34–1.8 nm) were 2400/1700 cm−3 for negative/positive ions, very high compared to most other measurements around the world. One reason behind these high concentrations could be the strong radon efflux from the soils around the Tumbarumba field site. Furthermore, comparison between night-time and daytime concentrations supported the view that cluster ions are produced close to the surface within the boundary layer also at night but that large ions are mostly produced in daytime. Finally, a previously unreported phenomenon, nocturnal aerosol formation, appeared in 32% of the analysed nights but was clustered almost entirely within six months from summer to autumn in 2006. From January to May, nocturnal formation was 2.5 times as frequent as daytime formation. Therefore, it appears that in summer and autumn, nocturnal production was the major mechanism for aerosol formation in Tumbarumba.

This paper addresses the potential role of surface wetness in ozone deposition to plant foliage. We studied Scots pine foliage in field conditions at the SMEARII field measurement station in Finland. We used a combination of data from flux measurement at the shoot (enclosure) and canopy scale (eddy covariance), information from foliage surface wetness sensors, and a broad array of ancillary measurements such as radiation, precipitation, temperature, and relative humidity. Environmental conditions were defined as moist during rain or high relative humidity and during the subsequent twelve hours from such events, circumstances that were frequent at this boreal site. From the measured fluxes we estimated the ozone conductance using it as the expression of the strength of ozone removal surface sink or total deposition. Further, we estimated the stomatal contribution and the remaining deposition was interpreted and analysed as the non-stomatal sink. The combined time series of measurements showed that both shoot and canopy-scale ozone total deposition were enhanced when moist conditions occurred. On average, the estimated stomatal deposition accounted for half of the measured removal at the shoot scale and one third at the canopy scale. However, during dry conditions the estimated stomatal uptake predicted the behaviour of the measured deposition, but during moist conditions there was disagreement. The estimated non-stomatal sink was analysed against several environmental factors and the clearest connection was found with ambient relative humidity. The relationship disappeared under 70% relative humidity, a threshold that coincides with the value at which surface moisture gathers at the foliage surface according to the leaf surface wetness measurements. This suggests the non-stomatal ozone sink on the foliage to be modulated by the surface films. We attempted to extract such potential modulation with the estimated film formation via the theoretical expression of adsorption. Whereas this procedure could predict the behaviour of the non-stomatal sink, it implied a chemical sink that was not accountable as simple ozone decomposition. We discuss the existence of other mechanisms whose relevance in the removal of ozone needs to be clarified, in particular: a significant nocturnal stomatal aperture neglected in the estimations, and a potentially large chemical sink offered by reactive biogenic organic volatile compounds.

The possible connections between the carbon balance of ecosystems and aerosol-cloud-climate interactions play a significant role in climate change studies. Carbon dioxide is a greenhouse gas, whereas the net effect of atmospheric aerosols is to cool the climate. Here, we investigated the connection between forest-atmosphere carbon exchange and aerosol dynamics in the continental boundary layer by means of multiannual data sets of particle formation and growth rates, of CO2 fluxes, and of monoterpene concentrations in a Scots pine forest in southern Finland. We suggest a new, interesting link and a potentially important feedback among forest ecosystem functioning, aerosols, and climate: Considering that globally increasing temperatures and CO2 fertilization are likely to lead to increased photosynthesis and forest growth, an increase in forest biomass would increase emissions of non-methane biogenic volatile organic compounds and thereby enhance organic aerosol production. This feedback mechanism couples the climate effect of CO2 with that of aerosols in a novel way.

BackgroundThe Rotation Invariant Vision Transformer (RViT) is a novel deep learning model tailored for brain tumor classification using MRI scans.MethodsRViT incorporates rotated patch embeddings to enhance the accuracy of brain tumor identification.ResultsEvaluation on the Brain Tumor MRI Dataset from Kaggle demonstrates RViT's superior performance with sensitivity (1.0), specificity (0.975), F1-score (0.984), Matthew's Correlation Coefficient (MCC) (0.972), and an overall accuracy of 0.986.ConclusionRViT outperforms the standard Vision Transformer model and several existing techniques, highlighting its efficacy in medical imaging. The study confirms that integrating rotational patch embeddings improves the model's capability to handle diverse orientations, a common challenge in tumor imaging. The specialized architecture and rotational invariance approach of RViT have the potential to enhance current methodologies for brain tumor detection and extend to other complex imaging tasks.

Attention deficit/hyperactivity disorder (ADHD) is a neuropsychological disorder that occurs in children and is characterized by inattention, impulsivity, and hyperactivity. Early and accurate diagnosis of ADHD is very important for effective intervention. The aim of this study is to develop a computer-aided approach to detecting ADHD using electroencephalogram (EEG) signals. Specifically, we explore a Gabor filter-based statistical features approach for the classification of EEG signals into ADHD and healthy control (HC). The EEG signal is processed by a bank of Gabor filters to obtain narrow-band signals. Subsequently, a set of statistical features is extracted. The computed features are then subjected to feature selection. Finally, the obtained feature vector is given to a classifier to detect ADHD and HC. Our approach achieves the highest classification accuracy of 96.4% on a publicly available dataset. Furthermore, our approach demonstrates better classification accuracy than the existing methods.

Polysilicon thick films have been found to be an irreplaceable option in various sensors and other microelectromechanical system (MEMS)-designs. Polysilicon is also a prospective option for replacing single-crystal silicon in customized silicon-on-insulator-substrates. Due to the nature of polysilicon, bonding for MEMS-purposes has so far concentrated on anodic bonding, which has drawbacks for instance in terms of process duration and thermal load. The objective of this work is to develop low-temperature direct bonding for various polysilicon films. Polysilicon films were grown at varying temperatures and pressures with and without boron doping. The films were polished by chemical–mechanical polishing and cleaned. Surface qualities were studied by atomic-force-microscope before bonding. Wafers were then activated with argon plasma and bonded to oxidized silicon, quartz and glass. Bonding quality was evaluated with scanning-acoustic-microscope, the crack-opening-method and HF-etching. Scanning-electron-microscopy was used to investigate film and interface quality. This development has led to a new kind of polishing process, where several microns of polysilicon are removed still leaving surface direct bondable. This is accomplished by a dedicated and effectively planarizing polishing process. Spontaneous bonding took place and good bonding quality was achieved after annealing at 200°C. [ABSTRACT FROM AUTHOR]

We have used the crack-opening method to study the mechanical exfoliation behavior in hydrogen-implanted and bonded Cz Si. We found that the crystal orientation and boron doping influence the temperature required for mechanical layer transfer. Boron implantation at doses >1013 cm-2 reduces the annealing temperature needed for mechanical exfoliation. The boron-doped epilayers followed similar exfoliation behavior as the boron-implanted samples. No lowering of the exfoliation temperature was observed for compensated and arsenic-doped Si layers. The hydrogen implantation converted the silicon wafer surface from p-type to n-type. The as-transferred Si layer was also found to be n-type after annealing at 200–450 °C. The p-type conductivity was restored upon annealing at around 600 °C. We believe that this conductivity conversion is due to the combined effect of ion-enhanced thermal donors and the presence of H-related shallow donors in the implanted layer. The p-type conductivity is restored at higher temperatures following the dissociation of the thermal donors and the out-diffusion of hydrogen. We also report that a good-quality silicon on glass layer can be obtained by the bonding and ion-cutting processes. [ABSTRACT FROM AUTHOR]

Salt stress is a major problem in most of the rice growing areas in the world. A major QTL Saltol associated with salt tolerance at the seedling stage has been mapped on chromosome 1 in rice. This study aimed to characterize the haplotype diversity at Saltol and additional QTLs associated with salt tolerance. Salt tolerance at the seedling stage was assessed in 54 rice genotypes in the scale of 1 to 9 score at EC = 10 dSm-1 under controlled environmental conditions. Seven new breeding lines including three KMR3/O. rufipogon introgression lines showed similar salt tolerant ability as FL478 and can be good sources of new genes/alleles for salt tolerance. Simple sequence repeat (SSR) marker RM289 showed only two alleles and RM8094 showed seven alleles. Polymorphic information content value varied from 0.55 for RM289 to 0.99 for RM8094 and RM493. Based on 14 SSR markers, the 54 lines were clearly separated into two major clusters. Fourteen haplotypes were identified based on Saltol linked markers with FL478 as the reference. Alleles of RM8094 and RM3412 can discriminate between the salt tolerant and susceptible genotypes clearly and hence can be useful in marker-assisted selection at the seedling stage. Other markers RM10720 on chromosome 1 and RM149 and RM264 on chromosome 8 can also distinguish tolerant and susceptible lines but with lesser stringency.

The school funding controversy revisitedSince the mid 1970s, there has been an ongoing debate in the Netherlands about Islam’s place in society. When following this debate, one might easily get the impression that we are dealing with a completely new and unprecedented phenomenon. A more thorough analysis, however, shows that this is only partly the case. When we put the debate about Islam into a historical perspective, focussing on the relationship between state and religion, the way in which Dutch society has dealt with issues of religious diversity, and how religious newcomers have been treated in the past, we are able to see that there are remarkable parallels with previous cases of religious emancipation and integration. In this article, the current debate about education and Islamic schools will be compared with aspects of the so-called school funding controversy that took place around the beginning of the 20th century. This article is part of the special issue 'Godsdienst in Nederland'.

Warm air in combination with frozen soil is a major cause of wintertime drought damage in evergreen plants in subalpine and boreal environments. We analyzed diurnal tree stem diameter variation (SDV), which reflects soil water uptake, canopy-level water vapor flux (Fw), stand photosynthesis (Ps), photosynthetically active radiation (PAR), soil and air temperatures (Ts and T air, respectively) and soil liquid water content (theta) to determine under what conditions photosynthesis is possible in wintertime and how crucial water uptake from soil is for photosynthesis. Measurements were made under field conditions in a Scots pine forest in southern Finland during winter 2002-2003. We found four wintertime periods when there was measurable Ps and SDV, the latter always starting 2-7 days after photosynthesis and both usually ending on the same day. Stand photosynthesis began when T air reached 3-4 degrees C and ended when T air dropped below -7 degrees C. The trees appeared to rely on stored stem water first and started taking up water from the soil a few days later, when the transpirational demand became strong enough. The more difficult it was to access soil water because of low Ts or low theta, the longer the trees used water stored in their stems. Even partial stem freezing did not prevent photosynthesis or soil water uptake.