Force-Induced Structural Changes in Spider Silk Fibers Introduced by ATR-FTIR Spectroscopy

Silk fibers have unique mechanical properties, and many studies of silk aim at understanding how these properties are related to secondary structure content, which often is determined by infrared spectroscopy. We report significant method-induced irreversible structural changes to both natural and synthetic spider silk fibers, derived from the widely used attenuated total reflection Fourier-transform infrared (ATR-FTIR) technique. By varying the force used to bring fibers into contact with the internal reflection elements of ATR-FTIR accessories, we observed correlated and largely irreversible changes in the secondary structure, with shape relaxation under pressure occurring within minutes. Fitting of spectral components shows that these changes agree with transformations from the alpha-helix to the beta-sheet secondary structure with possible contributions from other secondary structure elements. We further confirm the findings with IR microspectroscopy, where similar differences were seen between the pressed and unaffected regions of spider silk fibers. Our findings show that ATR-FTIR spectroscopy requires care in its use and in the interpretation of the results

First records of Anagraphis ochracea (Araneae: Gnaphosidae) for continental Italy and Sicily with new observations on its myrmecophilous lifestyle

In the present study we describe and discuss for the first time the peculiar myrmecophilous habits of Anagraphis ochracea (L. Koch, 1867) and its strong association with the ant species Messor ibericus Santschi, 1931. The study is based on behavioural observations carried out both in the field and in captivity, and sheds light on the lifestyle of this poorly studied and rarely observed species. We also recorded the presence of A. ochracea on continental Italy and Sicily for the first time; provide a brief overview of its taxonomical history and present photographs of adult and juvenile specimens, the egg sac and the copulatory organs of both sexes. Finally, we provide a DNA-barcode (COI) for A. ochracea, which is the first for the genus Anagraphis as well

ISR corrections to associated HZHZ production at future Higgs factories

We evaluate the QED corrections due to initial state radiation (ISR) to associated Higgs boson production in electron-positron ($e^+ e^-$) annihilation at typical energies of interest for the measurement of the Higgs properties at future $e^+ e^-$ colliders, such as CEPC and FCC-ee. We apply the QED Structure Function approach to the four-fermion production process $e^+ e^- \to \mu^+ \mu^- b \bar b$, including both signal and background contributions. We emphasize the relevance of the ISR corrections particularly near threshold and show that finite third order collinear contributions are mandatory to meet the expected experimental accuracy. We analyze in turn the r\^ole played by a full four-fermion calculation and beam energy spread in precision calculations for Higgs physics at future $e^+ e^-$ colliders.Comment: 11 pages, 3 figure

Charmed Hadrons from Coalescence plus Fragmentation in relativistic nucleus-nucleus collisions at RHIC and LHC

In a coalescence plus fragmentation approach we calculate the heavy baryon/meson ratio and the $p_T$ spectra of charmed hadrons $D^{0}$, $D_{s}$ and $\Lambda_{c}^{+}$ in a wide range of transverse momentum from low $p_T$ up to about 10 GeV and discuss their ratios from RHIC to LHC energies without any change of the coalescence parameters. We have included the contribution from decays of heavy hadron resonances and also the one due to fragmentation of heavy quarks which do not undergo the coalescence process. The coalescence process is tuned to have all charm quarks hadronizing in the $p_T\rightarrow 0$ limit and at finite $p_T$ charm quarks not undergoing coalescence are hadronized by independent fragmentation. The $p_T$ dependence of the baryon/meson ratios are found to be sensitive to the masses of coalescing quarks, in particular the $\Lambda_{c}/D^{0}$ can reach values of about $\rm 1\div 1.5$ at $p_T \approx \, 3$ \mbox{GeV}, or larger, similarly to the light baryon/meson ratio like $p/\pi$ and $\Lambda/K$, however a marked difference is a quite weak $p_T$ dependence with respect to the light case, such that a larger value at intermediate $p_T$ implies a relatively large value also for the integrated yields. A comparison with other coalescence model and with the prediction of thermal model is discussed.Comment: 13 pages, 9 figures. Fig. 5 updated and some minor changes in the tex

On the measurability of a numerical function with respect to a family of sets

The following document is a translation (from French to English) of: Gabriele H. Greco, Sur la mesurabilit\'e d'une fonction num\'erique par rapport \`a une famille d'ensembles, Rendiconti del Seminario Matematico della Universit\`a di Padova}, tome 65 (1981), pp. 163--176. Translated by: Jonathan M. Keith, School of Mathematics, Monash University, [email protected]. With thanks to: Prof. Andrea D'Agnolo, Editor-in-Chief of the above journal, for permission to publish this translation