Charge density study with the Maximum Entropy Method on model data of silicon. A search for non-nuclear attractors

1990 Sakata and Sato applied the maximum entropy method (MEM) to a set of structure factors measured earlier by Saka and Kato with the Pendellösung method. They found the presence of non-nuclear attractors, i.e., maxima in the density between two bonded atoms. We applied the MEM to a limited set of Fourier data calculated from a known electron density distribution (EDD) of silicon. The EDD of silicon was calculated with the program ADF-BAND. This program performs electronic structure calculations, including periodicity, based on the density functional theory of Hohenberg and Kohn. No non-nuclear attractor between two bonded silicon atoms was observed in this density. Structure factors were calculated from this density and the same set of structure factors that was measured by Saka and Kato was used in the MEM analysis. The EDD obtained with the MEM shows the same non-nuclear attractors that were later obtained by Sakata and Sato. This means that the non-nuclear attractors in silicon are really an artefact of the MEM

Lack of evidence for western flower thrips biotypes base don intra and inter-strain variation in gut bacteria

Western flower thrips is a polyphagous insect, which during the last 30 years has become a world wide pest. It was found earlier that these thrips are associated with a type of Erwinia species gut bacteria. In this study we examine the variation of bacteria within and between thrips individuals and try to find evidence for biotypes in western flower thrips regarding the type of gut bacteria. The existence of biotypes in this thrips species has been suggested by different authors. For example, thrips populations have been found that differ in resistance against pesticides and in their ability to transmit plant viruses. With biotypes we mean groups of individuals (strains, populations, lines) of a species which differ in one or more traits with other groups of that species. The gut bacteria of thrips are acquired by young thrips larvae via the host plant and have a beneficial effect on thrips development and oviposition. We studied thrips strains from different countries and host plants, and the isofemale lines that were created from them, on bean plant leaves. All thrips lines that we studied contained Erwinia species gut bacteria. Morphological and biochemical characteristics of gut bacteria from the thrips isofemale lines were similar to the Erwinia type strain from the reference, a thrips strain cultured on chrysanthemum in Amsterdam (TAC 93.XII.8). Per isofemale line we studied five thrips individuals and per thrips we studied four bacterial colonies, with RAPD markers. The genetic variation between bacteria isolated from thrips was as large among isofemale lines as within isofemale lines. No evidence for thrips biotypes was found. Bacteria within one thrips individual show a stronger degree of similarity than bacteria from different thrips individuals within a single rearing. This is probably due to a bottleneck caused by the limited number of successful infections of bacteria into the gut of the thrip

Reported adverse drug reactions during the use of inhaled steroids in children with asthma in the Netherlands

Objective: Inhaled corticosteroids (ICS) are widely used in the treatment of asthma. We studied the suspected adverse drug reactions (sADRs) reported during the use of ICS in the Netherlands. Methods: In the Netherlands, health professionals and patients can report suspected ADRs to the Pharmacovigilance Centre Lareb. All reported sADRs on ICS were categorised and assessed as to whether these were likely to be associated with use of the steroid. Age and gender adjusted Reported Odds Ratios (RORs) and Naranjo Scores (NS) were computed for sADRs reported more than 3 times. Results: Since 1984, sADRs of ICS were reported in 89 children (mean age 6 years), 48 (54%) were boys. Suspected drugs were fluticasone in 46 children (52%), budesonide in 21 (24%), and beclomethasone in 22 cases (24%). Psychiatric symptoms were reported in 19 children (21%; ROR 3.8, NS 3.6), growth retardation in 6 children (7%; ROR 47.8, NS 3.0) and rashes in 6 cases (7%; ROR 0.7, NS 2.4). There were 7 reports (8%; ROR 2.1, NS 3.4) concerning abnormalities of the teeth, 4 reports of alopecia (4%; ROR 3.3, NS 3.5), and 3 reports of hirsutism and hypertrichosis (NS 4.0). Non-fatal adrenal insufficiency was reported once. Conclusion: Alteration of behaviour was the most frequently reported sADR. There are more indications that alterations of behaviour could be a real sADR of ICS. Non-fatal adrenal insufficiency was the only reported possible life threatening sADR. The association of hypertrichosis and teeth abnormalities after ICS in children has not been reported in the literature before

Oscillatory Mechanisms of Preparing for Visual Distraction

Evidence shows that observers preactivate a target representation in preparation of a visual selection task. In this study, we addressed the question if and how preparing to ignore an anticipated distractor differs from preparing for an anticipated target. We measured EEG while participants memorized a laterally presented color, which was cued to be either a target or a distractor in two subsequent visual search tasks. Decoding the location of items in the search display from EOG channels revealed that, initially, the anticipated distractor attracted attention and could only be ignored later during the trial. This suggests that distractors could not be suppressed in advance but were represented in an active, attention-guiding format. Consistent with this, lateralized posterior alpha power did not dissociate between target and distractor templates during the delay periods, suggesting similar encoding and maintenance. However, distractor preparation did lead to relatively enhanced nonlateralized posterior alpha power, which appeared to gate sensory processing at search display onset to prevent attentional capture in general. Finally, anticipating distractors also led to enhanced midfrontal theta power during the delay period, a signal that was predictive of how strongly both target and distractor were represented in the search display. Together, our results speak against a distractor-specific advance inhibitory template, thus contrary to the preactivation of specific target templates. Rather, we demonstrate a general selection suppression mechanism, which serves to prevent initial involuntary capture by anticipated distracting input

The performance of organic electronic ratchets

Organic electronic ratchets rectify time-correlated external driving forces, giving output powers that can drive electronic circuitry. In this work their performance characteristics are investigated using numerical modeling and measurements. It is shown how the characteristic parameters of the time–varying asymmetric potential like length scales and amplitude, as well as the density and mobility of the charge carriers in the device influence the performance characteristics. Various ratchet efficiencies and their relations are discussed. With all settings close to optimum, a ratchet with charge displacement and power efficiencies close to 50% and 7% respectively is obtained