Description of an aerodynamic levitation apparatus with applications in Earth sciences

<p>Abstract</p> <p>Background</p> <p>In aerodynamic levitation, solids and liquids are floated in a vertical gas stream. In combination with CO₂-laser heating, containerless melting at high temperature of oxides and silicates is possible. We apply aerodynamic levitation to bulk rocks in preparation for microchemical analyses, and for evaporation and reduction experiments.</p> <p>Results</p> <p>Liquid silicate droplets (~2 mm) were maintained stable in levitation using a nozzle with a 0.8 mm bore and an opening angle of 60°. The gas flow was ~250 ml min^-1. Rock powders were melted and homogenized for microchemcial analyses. Laser melting produced chemically homogeneous glass spheres. Only highly (e.g. H₂O) and moderately volatile components (Na, K) were partially lost. The composition of evaporated materials was determined by directly combining levitation and inductively coupled plasma mass spectrometry. It is shown that the evaporated material is composed of Na > K >> Si. Levitation of metal oxide-rich material in a mixture of H₂and Ar resulted in the exsolution of liquid metal.</p> <p>Conclusions</p> <p>Levitation melting is a rapid technique or for the preparation of bulk rock powders for major, minor and trace element analysis. With exception of moderately volatile elements Na and K, bulk rock analyses can be performed with an uncertainty of ± 5% relative. The technique has great potential for the quantitative determination of evaporated materials from silicate melts. Reduction of oxides to metal is a means for the extraction and analysis of siderophile elements from silicates and can be used to better understand the origin of chondritic metal.</p

Differential Interactions of Sex Pheromone and Plant Odour in the Olfactory Pathway of a Male Moth

Most animals rely on olfaction to find sexual partners, food or a habitat. The olfactory system faces the challenge of extracting meaningful information from a noisy odorous environment. In most moth species, males respond to sex pheromone emitted by females in an environment with abundant plant volatiles. Plant odours could either facilitate the localization of females (females calling on host plants), mask the female pheromone or they could be neutral without any effect on the pheromone. Here we studied how mixtures of a behaviourally-attractive floral odour, heptanal, and the sex pheromone are encoded at different levels of the olfactory pathway in males of the noctuid moth Agrotis ipsilon. In addition, we asked how interactions between the two odorants change as a function of the males' mating status. We investigated mixture detection in both the pheromone-specific and in the general odorant pathway. We used a) recordings from individual sensilla to study responses of olfactory receptor neurons, b) in vivo calcium imaging with a bath-applied dye to characterize the global input response in the primary olfactory centre, the antennal lobe and c) intracellular recordings of antennal lobe output neurons, projection neurons, in virgin and newly-mated males. Our results show that heptanal reduces pheromone sensitivity at the peripheral and central olfactory level independently of the mating status. Contrarily, heptanal-responding olfactory receptor neurons are not influenced by pheromone in a mixture, although some post-mating modulation occurs at the input of the sexually isomorphic ordinary glomeruli, where general odours are processed within the antennal lobe. The results are discussed in the context of mate localization

Can galactography-guided stereotactic, 11-gauge, vacuum-assisted breast biopsy of intraductal lesions serve as an alternative to surgical biopsy?

The purpose of this study was to determine the value of galactography-guided, stereotactic, vacuum-assisted breast biopsy (VABB) for the assessment of intraductal breast lesions and its potential as a therapeutic tool that could eliminate the need for surgical excision. Eighteen patients (median age 64 years, range 37-80) with nipple discharge and galactography-verified intraductal lesions underwent galactography-guided, stereotactic, 11-gauge VABB followed by surgery. Histopathology findings from VABB and subsequent surgery were compared. Underestimation and false-negative rates were assessed. After VABB, histopathology revealed invasive ductal carcinoma (IDC) in three (17%), ductal carcinoma in situ (DCIS) in six (33%), high-risk lesions in six (33%) and benign lesions in three (17%) cases. After surgical biopsy, histopathology confirmed the previously established diagnosis in 11 lesions (61%). The underestimation rate for high-risk lesions and DCIS was 50% (6/12). The false-negative rate was 7% (1/14). Histopathology examination after surgery showed that not a single lesion had been completely removed at VABB. Galactography-guided VABB is a feasible diagnostic tool. However, its value as a therapeutic procedure is limited because of the high number of underestimated and missed lesions and because of the histopathological detection of lesions' remnants in every case. Surgical excision should be the therapeutic gold standard in cases of pathological nipple discharge and galactography abnormalities

DNA barcode data accurately assign higher spider taxa

The use of unique DNA sequences as a method for taxonomic identification is no longer fundamentally controversial, even though debate continues on the best markers, methods, and technology to use. Although both existing databanks such as GenBank and BOLD, as well as reference taxonomies, are imperfect, in best case scenarios “barcodes” (whether single or multiple, organelle or nuclear, loci) clearly are an increasingly fast and inexpensive method of identification, especially as compared to manual identification of unknowns by increasingly rare expert taxonomists. Because most species on Earth are undescribed, a complete reference database at the species level is impractical in the near term. The question therefore arises whether unidentified species can, using DNA barcodes, be accurately assigned to more inclusive groups such as genera and families—taxonomic ranks of putatively monophyletic groups for which the global inventory is more complete and stable. We used a carefully chosen test library of CO1 sequences from 49 families, 313 genera, and 816 species of spiders to assess the accuracy of genus and family-level assignment. We used BLAST queries of each sequence against the entire library and got the top ten hits. The percent sequence identity was reported from these hits (PIdent, range 75–100%). Accurate assignment of higher taxa (PIdent above which errors totaled less than 5%) occurred for genera at PIdent values >95 and families at PIdent values ≥ 91, suggesting these as heuristic thresholds for accurate generic and familial identifications in spiders. Accuracy of identification increases with numbers of species/genus and genera/family in the library; above five genera per family and fifteen species per genus all higher taxon assignments were correct. We propose that using percent sequence identity between conventional barcode sequences may be a feasible and reasonably accurate method to identify animals to family/genus. However, the quality of the underlying database impacts accuracy of results; many outliers in our dataset could be attributed to taxonomic and/or sequencing errors in BOLD and GenBank. It seems that an accurate and complete reference library of families and genera of life could provide accurate higher level taxonomic identifications cheaply and accessibly, within years rather than decades

Sex pheromone-plant odour interactions in the olfactory pathway of virgin and mated <i>A. ipsilon</i> males.

<p>Whereas pheromone sensitivity decreases drastically in AL output neurons after mating, heptanal sensitivity seems to increase already at the AL input level. Synergistic behavioural responses to odour mixtures in virgin males are correlated with enhanced antennal lobe responses. Likewise inhibitory behavioural responses to mixtures of pheromone and plant odour in mated males match inhibitory interactions within ordinary glomeruli of the antennal lobe. Pheromone reception and antennal lobe processing, on the other hand are inhibited by heptanal, independently of mating state. This might serve to improve temporal resolution of discontinuous stimuli, which are common in a natural environment. AL: antennal lobe; hep: heptanal; MGC: macroglomerular complex; mix: heptanal/pheromone mixture; OG: ordinary glomeruli; ORN: olfactory receptor neuron; phe: pheromone. Size of disks indicates response strength. Dash means no response. Numbers refer to previously published data: (1) Barrozo et al., 2011 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0033159#pone.0033159-Barrozo2" target="_blank">[26]</a> (2) This paper. (3) Gadenne et al., 2001 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0033159#pone.0033159-Gadenne1" target="_blank">[25]</a>. (4) Barrozo et al., 2010 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0033159#pone.0033159-Barrozo1" target="_blank">[21]</a>.</p

Heptanal-sensitive ORNs and OG calcium-evoked responses in virgin and mated males.

<p><b>A</b>) Typical recording showing an excitatory response to heptanal (100 µg), no response to the pheromone (10 ng) and the solvent (mineral oil), and excitation to the pheromone/heptanal mixture in a virgin male. The grey bar indicates the duration of the stimulus (0.5 s). <b>B</b>) Mean spike frequency of Hep-ORNs to pheromone (10 ng), heptanal at different doses, and their mixture in virgin (n = 13) and mated (n = 13) males. Hep-ORNs show dose-dependent response to heptanal, but no response to the pheromone and solvent. The addition of pheromone in the mixture does not modify the response of Hep-ORNs to heptanal at any dose tested. No differences were detected between virgin and mated males. <b>C</b>) Time course of odour-evoked calcium activity in the OG. The grey bar indicates the duration of the stimulus (1 s). <b>D</b>) Mean calcium responses in the OG to pheromone (10 ng), heptanal at different doses, and their mixture in virgin (n = 9) and mated (n = 8) males. Stimulation with pheromone induced no response. Heptanal-induced responses increased with the dose and were significantly higher in mated than in virgin males, although it was not different from mixture responses. Hep: heptanal; mix: pheromone/heptanal mixture; phe: pheromone; sol: solvent.</p

Behavioural responses of virgin <i>A. ipsilon</i> males to heptanal.

<p>The proportion of males showing an oriented flight towards the stimulus source was highest at a dose of 100 µg heptanal. Numbers in brackets represent the numbers of tested males. Bars with same letters are not statistically different (chi-square-test, p<0.05).</p

Odour-evoked calcium signals in the antennal lobe.

<p><b>A</b>) Example of an anatomical staining of a right antennal lobe (AL) with the outline of the entire AL and MGC. Two activity maps obtained in response to heptanal (10 µg) (hep10) and to the pheromone blend (10 ng) (phe10) are shown with the outline of the AL. Numbers next to dots indicate the position of the nine analysed ordinary glomeruli (1–9), as well as three analysed locations within the MGC, for which activity was pooled. <b>B</b>) Activity signals obtained in a mated male stimulated with four doses of heptanal (hep) (1–1000 µg), four presentations of pheromone (phe) at 10 ng, and the respective pheromone/heptanal mixtures (mix). All maps are scaled to the same minimum/maximum.</p