254 research outputs found
Above- and belowground herbivory jointly impact defense and seed dispersal traits in Taraxacum officinale
Plants are able to cope with herbivores by inducing defensive traits or growth responses that allow them to reduce or avoid the impact of herbivores. Since above- and belowground herbivores differ substantially in life-history traits, for example feeding types, and their spatial distribution, it is likely that they induce different responses in plants. Moreover, strong interactive effects on defense and plant growth are expected when above- and belowground herbivores are jointly present. The strengths and directions of these responses have been scarcely addressed in the literature. Using Taraxacum officinale, the root-feeding nematode Meloidogyne hapla and the locust Schistocerca gregaria as a model species, we examined to what degree above- and belowground herbivory affect (1) plant growth responses, (2) the induction of plant defensive traits, that is, leaf trichomes, and (3) changes in dispersal-related seed traits and seed germination. We compared the performance of plants originating from different populations to address whether plant responses are conserved across putative different genotypes. Overall, aboveground herbivory resulted in increased plant biomass. Root herbivory had no effect on plant growth. Plants exposed to the two herbivores showed fewer leaf trichomes than plants challenged only by one herbivore and consequently experienced greater aboveground herbivory. In addition, herbivory had effects that reached beyond the individual plant by modifying seed morphology, producing seeds with longer pappus, and germination success
Essais de régénération artificielle par semis de la subéraie de Numidie orientale.
La régénération naturelle du chêne-liège par semis, se heurte à de nombreux problèmes aussi bien biotiques qu'abiotiques. Des essais de semis «in situ» ont été effectués pour tester l'efficacité de certaines techniques, s'inspirant de travaux sur le changement de la morphologie du système racinaire de certaines essences forestières à enracinement pivotant. Les résultats obtenus sont concluants, à savoir : le crochetage du sol est primordial pour la réussite du semis direct de chêne-liège et qu'en son absence, la pré-germination des glands et, à un moindre titre, la décapitation du pivot, avant la mise en terre, peuvent s'avérer assez bénéfiques
Effect of vessel wettability on the foamability of "ideal" surfactants and "real-world" beer heads
The ability to tailor the foaming properties of a solution by controlling its chemical composition is highly desirable and has been the subject of extensive research driven by a range of applications. However, the control of foams by varying the wettability of the foaming vessel has been less widely reported. This work investigates the effect of the wettability of the side walls of vessels used for the in situ generation of foam by shaking aqueous solutions of three different types of model surfactant systems (non-ionic, anionic and cationic surfactants) along with four different beers (Guinness Original, Banks’s Bitter, Bass No 1 and Harvest Pale). We found that hydrophilic vials increased the foamability only for the three model systems but increased foam stability for all foams except the model cationic system. We then compared stability of beer foams produced by shaking and pouring and demonstrated weak qualitative agreement between both foam methods. We also showed how wettability of the glass controls bubble nucleation for beers and champagne and used this effect to control exactly where bubbles form using simple wettability patterns
Human Vascular Tissue Models Formed from Human Induced Pluripotent Stem Cell Derived Endothelial Cells
Here we describe a strategy to model blood vessel development using a well-defined induced pluripotent stem cell-derived endothelial cell type (iPSC-EC) cultured within engineered platforms that mimic the 3D microenvironment. The iPSC-ECs used here were first characterized by expression of endothelial markers and functional properties that included VEGF responsiveness, TNF-α-induced upregulation of cell adhesion molecules (MCAM/CD146; ICAM1/CD54), thrombin-dependent barrier function, shear stress-induced alignment, and 2D and 3D capillary-like network formation in Matrigel. The iPSC-ECs also formed 3D vascular networks in a variety of engineering contexts, yielded perfusable, interconnected lumen when co-cultured with primary human fibroblasts, and aligned with flow in microfluidics devices. iPSC-EC function during tubule network formation, barrier formation, and sprouting was consistent with that of primary ECs, and the results suggest a VEGF-independent mechanism for sprouting, which is relevant to therapeutic anti-angiogenesis strategies. Our combined results demonstrate the feasibility of using a well-defined, stable source of iPSC-ECs to model blood vessel formation within a variety of contexts using standard in vitro formats.National Institutes of Health (U.S.) (NIH 1UH2 TR000506-01)National Institutes of Health (U.S.) (3UH2 TR000506-02S1)National Institutes of Health (U.S.) (T32 HL007936-12)National Institutes of Health (U.S.) (RO1 HL093282)National Institutes of Health (U.S.) (R21 EB016381-01
Size limits the formation of liquid jets during bubble bursting
A bubble reaching an air–liquid interface usually bursts and forms a liquid jet. Jetting is relevant to climate and health as it is a source of aerosol droplets from breaking waves. Jetting has been observed for large bubbles with radii of R≫100 μm. However, few studies have been devoted to small bubbles (R<100 μm) despite the entrainment of a large number of such bubbles in sea water. Here we show that jet formation is inhibited by bubble size; a jet is not formed during bursting for bubbles smaller than a critical size. Using ultrafast X-ray and optical imaging methods, we build a phase diagram for jetting and the absence of jetting. Our results demonstrate that jetting in bubble bursting is analogous to pinching-off in liquid coalescence. The coalescence mechanism for bubble bursting may be useful in preventing jet formation in industry and improving climate models concerning aerosol production
Slow and fast diffusion in a lead sulphate gravity separation process
A model for the growth of lead sulphate particles in a gravity separation system
from the crystal glassware industry is presented. The lead sulphate particles are an undesirable
byproduct, and thus the model is used to ascertain the optimal system temperature configuration
such that particle extraction is maximised. The model describes the evolution of a single,
spherical particle due to the mass flux of lead particles from a surrounding acid solution. We
divide the concentration field into two separate regions. Specifically, a relatively small boundary
layer region around the particle is characterised by fast diffusion, and is thus considered quasistatic.
In contrast, diffusion in the far-field is slower, and hence assumed to be time-dependent.
The final system consisting of two nonlinear, coupled ordinary differential equations for the
particle radius and lead concentration, is integrated numerically
Euro plus Med-Checklist Notulae, 11
This is the eleventh of a series of miscellaneous contributions, by various authors, where hitherto unpublished data relevant to both the Med-Checklist and the Euro+Med (or Sisyphus) projects are presented. This instalment deals with the families Anacardiaceae, Asparagaceae (incl. Hyacinthaceae), Bignoniaceae, Cactaceae, Compositae, Cruciferae, Cyperaceae, Ericaceae, Gramineae, Labiatae, Leguminosae, Orobanchaceae, Polygonaceae, Rosaceae, Solanaceae and Staphyleaceae. It includes new country and area records and taxonomic and distributional considerations for taxa in Bidens, Campsis, Centaurea, Cyperus, Drymocallis, Engem, Hoffmannseggia, Hypopitys, Lavandula, Lithraea, Melilotus, Nicotiana, Olimarabidopsis, Opuntia, Orobanche, Phelipanche, Phragmites, Rumex, Salvia, Schinus, Staphylea, and a new combination in Drimia.Peer reviewe
Treatment outcomes of fixed-dose combination versus separate tablet regimens in pulmonary tuberculosis patients with or without diabetes in Qatar
Background: Tuberculosis is considered the second most common cause of death due to infectious agent. The
currently preferred regimen for treatment of pulmonary tuberculosis (PTB) is isoniazid, rifampin, pyrazinamide, and
ethambutol, which has been used either as separate tablets (ST) or as fixed-dose combination (FDC). To date, no
studies have compared both regimens in Qatar. We aim to evaluate the safety and effectiveness of FDC and ST
regimen for treating PTB, in addition to comparing safety and efficacy of FDC and ST regimens in patients with
diabetes treated for TB.
Methods: A retrospective observational study was conducted in two general hospitals in Qatar. Patients diagnosed
with PTB received anti-tuberculosis medications (either as FDC or ST) administered by the nurse. Sputum smears
were tested weekly. We assessed the time to negative sputum smear and incidence of adverse events among FDC
and ST groups.
Results: The study included 148 patients. FDC was used in 90 patients (61%). Effectiveness was not different
between FDC and ST regimens as shown by mean time to sputum conversion (29.9 ± 18.3 vs. 35.6 ± 23 days, p = 0.12).
Similarly, there was no difference in the incidence of adverse events, except for visual one that was higher in ST group.
Among the 33 diabetic patients, 19 received the FDC and had faster sputum conversion compared to those who
received ST (31 ± 12 vs. 49.4 ± 30.9 days, p = 0.05). Overall, diabetic patients needed longer time for sputum conversion
and had more hepatotoxic and gastric adverse events compared to non-diabetics.
Conclusion: ST group had higher visual side effects compared to FDC. FDC may be more effective in diabetic patients;
however, further studies are required to confirm such finding.PublishedN/
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