How spiders hunt heavy prey: the tangle web as a pulley and spider's lifting mechanics observed and quantified in the laboratory

The spiders of Theridiidae's family display a peculiar behaviour when they hunt extremely large prey. They lift the quarry, making it unable to escape, by attaching pre-tensioned silk threads to it. In this work, we analysed for the first time in the laboratory the lifting hunting mechanism and, in order to quantify the phenomenon, we applied the lifting mechanics theory. The comparison between the experiments and the theory suggests that, during the process, spiders do not stretch the silk too much by keeping it in the linear elastic regime. We thus report here further evidence for the strong role of silk in spiders' evolution, especially how spiders can stretch and use it as an external tool to overcome their muscles’ limits and capture prey with large mass, e.g. 50 times the spider's mass.

The diverging evolutionary history of opsin genes in Diptera

Opsin receptors mediate the visual process in animals and their evolutionary history can provide precious hints on the ecological factors that underpin their diversification. Here we mined the genomes of more than 60 Dipteran species and reconstructed the evolution of their opsin genes in a phylogenetic framework. Our phylogenies indicate that dipterans possess an ancestral set of five core opsins which have undergone several lineage-specific events including an independent expansion of low wavelength opsins in flies and mosquitoes and numerous family specific duplications and losses. Molecular evolutionary studies indicate that gene turnover rate, overall mutation rate, and site-specific selective pressure are higher in Anopheles than in Drosophila; we found signs of positive selection in both lineages, including events possibly associated with their peculiar behaviour. Our findings indicate an extremely variable pattern of opsin evolution in dipterans, showcasing how two similarly aged radiations - Anopheles and Drosophila - can be characterized by contrasting dynamics in the evolution of this gene family.

Symmetric-in-Plane Compression of Polyamide Pantographic Fabrics—Modelling, Experiments and Numerical Exploration

Symmetric in-plane compression of a pantographic lattice structure is modelled and simulated, and the results are compared to previously available experimental data. Said experimental results had shown a peculiar behaviour: depending on the fiber density, the deformed shape could present either one or two swellings under compression. The present article is a preliminary modelling attempt aiming at capturing that behaviour numerically.

Deriving stellar parameters from GALANTE photometry: bias and precision

ABSTRACT In this paper, we analyse how to extract the physical properties from the GALANTE photometry of a stellar sample. We propose a direct comparison between the observational colours (photometric bands normalized to the 515 nm central wavelength) and the synthetic colours derived from different stellar libraries. We use the reduced χ2 as the figure of merit for selecting the best fitting between both colour sets. The synthetic colours of the Next Generation Spectral Library (NGSL) provide a valuable sample for testing the uncertainty and precision of the stellar parameters derived from observational data. Reddening, as an extrinsic stellar physical parameter becomes a crucial variable for accounting for the errors and bias in the derived estimates: the higher the reddenings, the larger the errors and uncertainties in the derived parameters. NGSL colours also enable us to compare different theoretical stellar libraries for the same set of physical parameters, where we see how different catalogues of models can provide very different solutions in a, sometimes, non-linear way. This peculiar behaviour makes us to be cautious with the derived physical parameters obtained from GALANTE photometry without previous detailed knowledge of the theoretical libraries used to this end. In addition, we carry out the experiment of deriving physical stellar parameters from some theoretical libraries, using some other libraries as observational data. In particular, we use the Kurucz and Coelho libraries, as input observational data, to derive stellar parameters from Coelho + TLUSTY and Kurucz + TLUSTY stellar libraries, respectively, for different photometric errors and colour excesses.

Modeling of the irradiation effect on some physicochemical properties of metoprolol tartrate for safe medical uses

The effect of gamma-irradiation and ionizing radiation (high-energy electrons beam) on the physicochemical properties of metoprolol tartrate at the solid phase and aqueous solution, has been investigated in the present study to model some properties affected by absorbed doses and to reveal some interesting mutual causal correlation. The proposed some interesting models can be adapted to other experimental conditions, and the newly obtained values of the adjustable parameters could be an excellent criterion of the state quality of the metoprolol tartrate or for other additional interpretations. The peculiar behaviour of variation of physicochemical properties against dose leads us to confirm the suggested optimized doses mentioned in previous work, for sterilization and safe medical uses.

Detecting metaphor – what case forms may reveal about a conceptualization

The figurativeness of language expressions is not always obvious. While in rhetoric such unobtrusiveness may be a welcome quality, in linguistic studies, which have proved the important epistemological function of metaphor, it is vital that a reliable method for detecting metaphoricity in language be developed. The MIP proposed by the Pragglejaz group of researchers into metaphor, whose main concern is determining whether the sense represented by a given unit in a specific context contrasts or not with its basic, primary, typically “physical” meaning, does not seem to be always reliable since the contrast between a current and a basic meaning is not always evident and may be disputable in the case of words whose meaning is co-determined by context, as, e.g., the sense of the noun collectors in the phrase collectors of stories referring to the Grimm brothers. This method is also likely allow for the so-called grammatical metaphors, identified by Panther and Thornburg (2009) going unnoticed, since in their case the words involved represent their basic, physical senses. An example of the latter is the peculiar inflection of brand names marked for the masculine gender in Polish. Specifically, this is the issue of obligatory applying the declensional pattern characteristic of masculine animate nouns to masculine brand names referring to commercial products, such as cars, watches, computers, etc. The point is that the accusative case form of such words functioning as objects of verbs like buy, see, have is equal to the genitive, as is normal of animate nouns, rather than to the nominative, which is typical of animate ones – a group, to which brand names, after all, belong. This peculiar behaviour of a specific category of nouns may be interpreted as a symptom of construing their referents in a way in terms of living creatures, which seems to be confirmed by the fact that many owners develop emotional attitudes to objects of personal use. It is the metaphorical construal that seems to determine the grammatical form of certain nouns referring to them.

X-ray and optical monitoring of the December 2017 outburst of the Be/X-ray binary AXJ0049.4–7323

AXJ0049.4–7323 (SXP 756) is a Be/X-ray binary that shows an unusual and poorly understood optical variability that consists of periodic and bright optical outbursts, simultaneous with X-ray outbursts, characterised by a highly asymmetric profile. The periodicity of the outbursts is thought to correspond to the orbital period of the neutron star. To understand the peculiar behaviour shown by this source, we performed the first multi-wavelength monitoring campaign during the periastron passage of December 2017. The monitoring lasted for about 37 days and consisted of X-ray, near-ultraviolet, and optical data from the Neil Gehrels Swift Observatory, the optical I band from the OGLE survey, and spectroscopic observations of the Hα line performed with the 3.9 m Anglo-Australian Telescope. These observations revealed AXJ0049.4–7323 during an anomalous outburst having remarkably different properties compared to the previous ones. In the I band, it showed a longer rise timescale (∼60 days instead of 1–5 days) and a longer decay timescale. At the peak of the outburst, it showed a sudden increase in luminosity in the I band, corresponding to the onset of the X-ray outburst. The monitoring of the Hα emission line showed a fast and highly variable profile composed of three peaks with variable reciprocal brightness. To our knowledge, this is the second observation of a variable three-peak Hα profile of a Be/X-ray binary, after A0535+26. We interpreted these results as a circumstellar disc warped by tidal interactions with the neutron star in a high eccentricity orbit during its periastron passage. The fast jump in optical luminosity at the peak of the outburst and the previous asymmetric outbursts might be caused by the reprocessing of the X-ray photons in the circumstellar disc or the tidal displacement of a large amount of material from the circumstellar disc or the outer layers of the donor star during the periastron passage of the neutron star, which led to an increase in size of the region emitting in the I band. Further multi-wavelength observations are necessary to discriminate among the different scenarios proposed to explain the puzzling optical and X-ray properties of AXJ0049.4–7323.

A peculiar behaviour of liquid jet impact

Coalescent masses of fluid, formed upon liquid jet impact, should exhibit either dripping or jetting regardless of the distance between the nozzles. The study reveals that above a certain flow rate, by increasing this distance, the coalescent mass enters a dripping state, when only a jetting regime is previously present. This is followed again by a jetting regime before breakup which occurs at a critical distance. The upper limit of this dripping state is achieved when Bond number is equal to unity, this result being valid below a certain critical Reynolds number.