How a sticky fluid facilitates prey retention in a carnivorous pitcher plant (Nepenthes rafflesiana)

Nepenthes pitcher plants live in nutrient-poor soils and produce large pitfall traps to obtain additional nutrients from animal prey. Previous research has shown that the digestive secretion in N. rafflesiana is a sticky viscoelastic fluid that retains insects much more effectively than water, even after significant dilution. Although the retention of prey is known to depend on the fluid's physical properties, the details of how the fluid interacts with insect cuticle and how its sticky nature affects struggling insects are unclear. In this study, we investigated the mechanisms behind the efficient prey retention in N. rafflesiana pitcher fluid. By measuring the attractive forces on insect body parts moved in and out of test fluids, we show that it costs insects more energy to free themselves from pitcher fluid than from water. Moreover, both the maximum force and the energy required for retraction increased after the first contact with the pitcher fluid. We found that insects sink more easily into pitcher fluid than water and, accordingly, the surface tension of N. rafflesiana pitcher fluid was lower than that of water (60.2 vs. 72.3 mN/m). By analysing the pitcher fluid’s wetting behaviour, we demonstrate that it strongly resists dewetting from all surfaces tested, leaving behind residual films and filaments that can facilitate re-wetting. This inhibition of dewetting may be a further consequence of the fluid's viscoelastic nature and likely represents a key mechanism underlying prey retention in Nepenthes pitcher plants.V.K. and W.F. were funded by the EU Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 642861. S.S. was funded by the Cambridge India Ramanujan Scholarship

Elevated fasting insulin predicts the future incidence of metabolic syndrome: a 5-year follow-up study

<p>Abstract</p> <p>Background</p> <p>There is controversy about the specific pathophysiology of metabolic syndrome (MS) but several authors have argued that hyperinsulinemia is a key feature of the cluster. We aimed to assess whether the baseline insulin levels could predict the development of MS in a well characterised cohort of otherwise healthy adults who were followed over a five year period.</p> <p>Methods</p> <p>We identified 2, 350 Koreans subjects who did not have MS in 2003 and who were followed up in 2008. The subjects were divided into 4 groups according to the baseline quartiles of fasting insulin, and the predictors of the incidence of MS were analyzed using multivariate regression analysis.</p> <p>Results</p> <p>Over the follow up period, 8.5% of the cohort developed MS. However, 16.4% of the subjects in the highest quartile of the insulin levels developed MS. In a model that included gender, age, the smoking status, the exercise level, alcohol consumption and the systolic blood pressure, the subjects in the highest quartile of the insulin levels had more than a 5 times greater risk of developing MS compared that of the subjects in the lowest quartile. This predictive importance remained significant even after correcting for all the individual features of MS.</p> <p>Conclusions</p> <p>These data suggest that high baseline fasting insulin levels are independent determinants for the future development of MS.</p

Surface mass balance contributions to acceleration of Antarctic ice mass loss during 2003-2013

Recent observations from satellite gravimetry (the Gravity Recovery and Climate Experiment (GRACE) mission) suggest an acceleration of ice mass loss from the Antarctic Ice Sheet (AIS). The contribution of surface mass balance changes (due to variable precipitation) is compared with GRACE-derived mass loss acceleration by assessing the estimated contribution of snow mass from meteorological reanalysis data. We find that over much of the continent, the acceleration can be explained by precipitation anomalies. However, on the Antarctic Peninsula and other parts of West Antarctica, mass changes are not explained by precipitation and are likely associated with ice discharge rate increases. The total apparent GRACE acceleration over all of the AIS between 2003 and 2013 is −13.6 ± 7.2 Gt/yr^2. Of this total, we find that the surface mass balance component is −8.2 ± 2.0 Gt/yr^2. However, the GRACE estimate appears to contain errors arising from the atmospheric pressure fields used to remove air mass effects. The estimated acceleration error from this effect is about 9.8 ± 5.8 Gt/yr^2. Correcting for this yields an ice discharge acceleration of −15.1 ± 6.5 Gt/yr^2

Effect of inorganic-to-organic mass ratio on the heterogeneous OH reaction rates of erythritol: Implications for atmospheric chemical stability of 2-methyltetrols

The 2-methyltetrols have been widely chosen as chemical tracers for isoprene-derived secondary organic aerosols. While they are often assumed to be relatively unreactive, a laboratory study reported that pure erythritol particles (an analog of 2-methyltetrols) can be heterogeneously oxidized by gas-phase OH radicals at a significant rate. This might question the efficacy of these compounds as tracers in aerosol source-apportionment studies. Additional uncertainty could arise as organic compounds and inorganic salts often coexist in atmospheric particles. To gain more insights into the chemical stability of 2-methyltetrols in atmospheric particles, this study investigates the heterogeneous OH oxidation of pure erythritol particles and particles containing erythritol and ammonium sulfate (AS) at different dry inorganic-to-organic mass ratios (IOR) in an aerosol flow tube reactor at a high relative humidity of 85 %. The same reaction products are formed upon heterogenous OH oxidation of erythritol and erythritol-AS particles, suggesting that the reaction pathways are not strongly affected by the presence and amount of AS. On the other hand, the effective OH uptake coefficient, eff, is found to decrease by about a factor of 20 from 0:450:025 to 0:020:001 when the relative abundance of AS increases and the IOR increases from 0.0 to 5.0. One likely explanation is the presence of dissolved ions slows down the reaction rates by decreasing the surface concentration of erythritol and reducing the frequency of collision between erythritol and gas-phase OH radicals at the particle surface. Hence, the heterogeneous OH reactivity of erythritol and likely 2-methyltetrols in atmospheric particles would be slower than previously thought when the salts are present. Given 2-methyltetrols often coexist with a significant amount of AS in many environments, where ambient IOR can vary from 1:89 to 250, our kinetic data would suggest that 2-methyltetrols in atmospheric particles are likely chemically stable against heterogeneous OH oxidation under humid conditions

A Natural Application for High Temperature Superconductors: a Bearing for the Azimuth Mount of a Lunar Telescope

A bearing for telescope mounts on the moon has to function in a cold dusty vacuum environment that impairs the operation of almost all traditional bearings, but it is a natural environment for bearings constructed out of magnets and high temperature superconductors. The challenge lies not so much in the weight of the telescope that has to be supported, but in the smoothness of forces required for precision positioning control over a long stretch of time without human intervention. In this paper, we present a design of hybrid superconductor magnet bearings intended for use on the azimuth mount of an altitude-azimuth telescope mount system. In addition to the general features of hybrid super conducting magnet bearings, we will address particular issues connected with the application of these bearings on a telescope mount

θ\theta Effects in Chern-Simons QED2+1{\rm QED}_{2+1} with a Four-Fermi Interaction

We investigate the effects of the Chern-Simons coupling on the high energy behavior in the $(2+1)$-dimensional Chern-Simons QED with a four-Fermi interaction. Using the $1/N$ expansion we discuss the Chern-Simons effects on the critical four-Fermi coupling at $O(1/N)$ and the $\beta$ function around it. High-energy behavior of Green's functions is also discussed. By explicit calculation, we find that the radiative correction to the Chern-Simons coupling vanishes at $O(1/N)$ in the broken phase of the dynamical parity symmetry. We argue that no radiative corrections to the Chern-Simons term arise at higher orders in the $1/N$ expansion.Comment: 13 pages, 6 figures not included, LaTeX, SNUTP 92-9

Characterisation of chemical composition and structural features of novel antimicrobial nanoparticles

© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This is an open access article distributed under the Creative Commons Attribution License (CC BY 4.0) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Three antimicrobial nanoparticle types (AMNP0, AMNP1 and AMNP2) produced using the TesimaTM thermal plasma technology were investigated and their compositions determined using a combination of analytical methods. Scanning electron micrograph provided the morphology of these particles with observed sizes ranging from 10 – 50 nm. Whilst FTIR spectra confirmed the absence of polar bonds and organic impurities, strong Raman active vibrational bands at ca. 1604 and 1311 cm-1 ascribed to C-C vibrational motions were observed. Carbon signals resonated at δC126 ppm in solid state NMR spectra confirmed sp2 hybridised carbons were present in high concentration in two of the nanoparticle types (AMNP1 and AMNP2). X-ray powder diffraction suggested AMNP0 contains single phase WC in a high state of purity and multiple phases of WC/WC1-x were identified in both AMNP1 and AMNP2. Finally, XPS surface analyses revealed and quantified the elemental ratios in these composite formulations.Peer reviewe

Substituted N-(Biphenyl-4′-yl)methyl (R)-2-Acetamido-3-methoxypropionamides: Potent Anticonvulsants That Affect Frequency (Use) Dependence and Slow Inactivation of Sodium Channels

, We prepared 13 derivatives of N-(biphenyl-4′-yl)methyl (R)-2-acetamido-3-methoxypropionamide that differed in type and placement of a R-substituent in the terminal aryl unit. We demonstrated that the R-substituent impacted the compound’s whole animal and cellular pharmacological activities. In rodents, select compounds exhibited excellent anticonvulsant activities and protective indices (PI = TD50/ED50) that compared favorably with clinical antiseizure drugs. Compounds with a polar, aprotic R-substituent potently promoted Na+ channel slow inactivation and displayed frequency (use) inhibition of Na+ currents at low micromolar concentrations. The possible advantage of affecting these two pathways to decrease neurological hyperexcitability is discussed

Prion Protein Polymorphisms Affect Chronic Wasting Disease Progression

Analysis of the PRNP gene in cervids naturally infected with chronic wasting disease (CWD) suggested that PRNP polymorphisms affect the susceptibility of deer to infection. To test this effect, we orally inoculated 12 white-tailed deer with CWD agent. Three different PRNP alleles, wild-type (wt; glutamine at amino acid 95 and glycine at 96), Q95H (glutamine to histidine at amino acid position 95) and G96S (glycine to serine at position 96) were represented in the study cohort with 5 wt/wt, 3 wt/G96S, and 1 each wt/Q95H and Q95H/G96S. Two animals were lost to follow-up due to intercurrent disease. The inoculum was prepared from Wisconsin hunter-harvested homozygous wt/wt animals. All infected deer presented with clinical signs of CWD; the orally infected wt/wt had an average survival period of 693 days post inoculation (dpi) and G96S/wt deer had an average survival period of 956 dpi. The Q95H/wt and Q95H/G96S deer succumbed to CWD at 1,508 and 1,596 dpi respectively. These data show that polymorphisms in the PRNP gene affect CWD incubation period. Deer heterozygous for the PRNP alleles had extended incubation periods with the Q95H allele having the greatest effect