Torsion loads on a ski-touring boot sole during uphill climbing and downhill skiing

Introduction: Ski-touring is a well settled winter activity in mountain regions. Differently to alpine skiing, the high ground is reached by climbing the mountain using sealskins under the skis and special boots and bindings. This difference introduces higher concerns on the weight of the equipment rather than other skiing disciplines. Nevertheless, to allow a safe and enjoyable skiing the structural properties of the boot must be guaranteed. Past studies aimed to determine loads and stiffness of alpine and cross-country skiboots using in field or laboratory approaches [1,2,3]. The present study aims to provide an estimation of the torsion loads acting on the ski-touring boot sole during walking and skiing phases. Such measure is helpful towards the design of more performant ski-touring boots. Methods: A ski-touring boot (left side, size: 26.5 MP) was prepared with strain gauge bridges and calibrated using a servohydraulic machine (Fig 1a). First, the outer rubber sole was cut to reach the plastics of the boot shell. Then, two full Wheatstone bridge were placed on the sole in middle length of the boot to measure torsion and flexion loads. To calibrate the boot sole close to in-field testing conditions, a silicone dummy foot was fitted inside the boot. Then, the skiboot was mounted on ski-touring bindings surrogates attached to a servohydraulic torsion machine. The torsion channel was calibrated by applying a quasi-static ramp between -5/+5°, reading the applied torque and bridge output synchronously to obtain the bridge sensitivity. The in-field test took place in Val di Zoldo (BL, Italy), outside temperature was 10 °C, on a slope covered by spring snow. The instrumented boot was connected to a SoMat eDAQ lite data acquisition system (HBM) powered with a 12 V battery, instrumentation was fitted in a small backpack (total weight: 3 kg). Data were acquired at a 500 Hz sampling rate. Tests were performed by an amateur skier (height: 175 cm, weight: 70 kg, age: 25 yr) who climbed and skied an off-piste route graded BS in Blachère scale. The participant performed a 400 m gain uphill climbing which was divided into straight climb, and left/right side traverses. During the descent the participant was asked to perform narrow and wide slaloms at its own typical speed. Overall length of the test was 45 minutes. Peak and valleys of data were computed and averaged for each phase to obtain the range of the load. The mean of the signal during each phase was also computed. Internal rotating torques applied to the boot front are positive. Results and discussion: Calibration trials gave a bridge sensitivity of -12.59 Nm/(mV/V) with an applied torque ranging from -50 to +50 Nm. In field test data (Fig 1b, Table 1) evidenced highest torque ranges during skiing phase; torque mean values showed opposite sign in the two sides of uphill climbing. In both phases the range was well below the torque reached during the calibration trials. This suggests that ski-touring boot torsion loads should be based on maximal values collected during skiing trials. The analysis and implementation of further measurement channels such as the sole flexion and the ski/walk links will be performed to improve the understanding of climbing and skiing loads. More tests are being conducted to account for subject variability and snow/terrain conditions. 1. Petrone N., Marcolin G., Centofante E., Atzori B. (2010), Analysis of the structural behavior of an innovative reinforced ski boot. Procedia Engineering. 2. 2599-2604. 10.1016/j.proeng.2010.04.038. 2. Petrone N., Marcolin G., Panizzolo F., (2013), The effect of boot stiffness on field and laboratory flexural behavior of alpine ski boots. Sports Engineering. 16. 10.1007/s12283-013-0133-z. 3. Hladnik J. Resman F. Jerman B. (2012), Torsion stiffness of a racing cross-country ski boot. Proceedings of the Institution of Mechanical Engineers Part P Journal of Sports Engineering and Technology

The octahedral sheet of metamorphic 2M1-phengites: A combined EMPA and AXANES study

Two types of metamorphic phengites are known: one is linked to high pressure and is 3T; the other is 2M{sub 1}, and its composition is linked to rock-compositional constraints. This work investigates the octahedral sheet crystal-chemical differences between the two phengite types. Seven dioctahedral micas were studied: (1) one 3T phengite from an ultrahigh-pressure metagranitoid in the Dora Maira massif, Italy (P {approx} 4.3 GPa, T {approx} 730 C); (2) five 2M{sub 1} phengites from medium-P orthogneisses in the Eastern Alps metamorphic basement, Italy (P {le} 0.7 GPa, T {approx} 500-600 C); and (3) one 2M{sub 1} ferroan muscovite from pegmatite in Antarctica (P {le} 0.2 GPa, T {approx}500 C). All micas display significant extents of celadonite substitution. In particular, the 2M{sub 1}-phengite formulae (calculated on the basis of 11 O) have 0.68 < {sup IV}Al < 0.82 atoms per formula unit (apfu); octahedral atoms are dominated by Al (1.6-1.8 apfu), with minor and variable Fe (0.20-0.35 apfu) and Mg (0.05-0.17 apfu), and very minor Ti, Mn, and Cr. Total octahedral occupancies are slightly above 2.00 apfu, i.e., there seems to be partial occupancy of the third M site. For all micas, we recorded XAFS spectra on mosaics of carefullymore » separated flakes oriented flat on a plastic support that could be rotated so as to account for the polarization of the synchrotron radiation beam, and we processed them on the basis of the AXANES theory. Spectra show angle-dependent absorption variations for Al and Fe, which can be deconvoluted and fitted by dichroic effects. Pre-edges consistently show most Fe to be Fe{sup 3+} and little angle-dependent intensity variations. The 2M{sub 1}-ferroan muscovite from Antarctica displays the same AXANES behavior as 2M{sub 1}-phengites. By contrast, the ultrahigh-pressure 3T-phengite from Dora Maira (having {sup IV}Al = 0.42 apfu, and Al and Mg as the dominant octahedral constituents) has XAFS spectra that differ significantly. Not only is the {sup IV}Al feature strongly reduced, in agreement with the increased Si content, but also Fe XAFS spectra show one broad feature only, indicating that all Fe is Fe{sup 2+} in a fully disordered distribution with no angle-dependent variations. We conclude that this 3T-phengite is actually contaminated by exsolved Fe-bearing pyrope platelets, which cannot be resolved under SEM examination; by contrast, the 2M{sub 1}-phengites, unrelated to high-pressure, suggest Al/Fe{sup 3+} order over the M1 and (M2, M3) sites, as also does the 2M{sub 1} pegmatitic muscovite.« les

Participatory Design and Critical Media Studies:A Convivial Conversation

Nell'era della società delle piattaforme, i Critical Media Studies si trovano di fronte alla sfida di sviluppare non solo proposte teoriche in grado di affrontare criticamente il potere esercitato sulla società dalle piattaforme digitali di proprietà della GAFAM, ma anche di immaginare una prassi capace di cambiare l'economia politica di questo ecosistema mediatico digitale guidato dalle aziende. Per fare questo, crediamo che il Participatory Design e i Critical Media Studies debbano dialogare quando si tratta di quadri teorici e pratiche di intervento. In questo articolo proponiamo di iniziare questo dialogo partendo dal lavoro di Ivan Illich, in particolare dal suo libro Tools for Conviviality. Riteniamo che per immaginare un possibile processo di progettazione dei media digitali in grado di evitare la creazione di monopoli radicali, sia necessario adottare un approccio di Convivial Participatory Design in cui le questioni relative alla scala, ai bisogni delle persone e alle disuguaglianze di potere siano considerate dai designer in collaborazione con gli utenti.In the age of platform society, Critical Media Studies are faced with the challenge of developing not only theoretical proposals capable of critically addressing the power exerted on society by GAFAM-owned digital platforms, but also of envisioning a praxis capable of changing the political economy of this corporate-driven digital media ecosystem. To do this, we believe that Participatory Design and Critical Media Studies should dialogue when it comes to theoretical frameworks and intervention practices. In this paper we propose to start this dialogue building upon the work of Ivan Illich, especially his book Tools for Conviviality. We find that in order to imagine a possible digital media design process able to avoid the creation of radical monopolies, it is necessary to adopt a Convivial Participatory Design approach where issues related to scale, people needs and power inequalities are considered by designers in collaboration with the users

Letter. On the activation of [CrCl3{R-SN(H)S-R}] catalysts for selective trimerization of ethene: a freeze-quench Cr K-edge XAFS study

Homogeneous chromium catalysts for the selective conversion of ethene to hex-1-ene are formed from Cr(III) reagents, amino-thioether ligands of the type HN(CH2CH2SR)2, and aluminum reagents. In this study the early activation steps are investigated by EPR, UV-visible and Cr K-edge XAFS spectroscopy; rapid stopped-flow mixing and a freeze-quench allows good quality EXAFS analysis of a species formed in ~ 1 second of reaction. This is shown to involve reduction to Cr(II) and deprotonation of a NH group of the auxiliary ligand. This 4-coordinate metal-center may act as precursor for the coordination of ethene and subsequent selective oligomerization

Interlayer potassium and its neighboring atoms in micas : Crystal-chemical modeling and XANES spectroscopy

A detailed description of the interlayer site in trioctahedral true micas is presented based on a statistical appraisal of crystal-chemical, structural, and spectroscopic data determined on two sets of trioctahedral micas extensively studied by both X-ray diffraction refinement on single crystals (SC-XRD) and X-ray absorption fine spectroscopy (XAFS) at the potassium K -edge. Spectroscopy was carried out on both random powders and oriented cleavage flakes, the latter setting taking advantage of the polarized character of synchrotron radiation. Such an approach (AXANES) is shown to be complementary to crystal-chemical investigation based on SC-XRD refinement. However, the results are not definitive as they focus on few samples having extreme features only (e.g., end-members, unusual compositions, and samples with extreme and well-identified substitution mechanisms). The experimental absorption K -edge (XANES) for potassium was decomposed by calculation and extrapolated into a full in-plane absorption component (σ||) and a full out-of-plane absorption component (σ⊥). These two patterns reflect different structural features: σ|| represents the arrangement of the atoms located in the mica interlayer space and facing tetrahedral sheets; σ⊥ is associated with multiple-scattering interactions entering deep into the mica structure, thus also reflecting interactions with the heavy atoms (essentially Fe) located in the octahedral sheet. The out-of-plane patterns also provide insights into the electronic properties of the octahedral cations, such as their oxidation states (e.g., Fe2+ and Fe3+) and their ordering (e.g., trans - vs. cis -setting). It is also possible to distinguish between F- and OH-rich micas due to peculiar absorption features originating from the F vs. OH occupancy of the O4 octahedral site. Thus, combining crystal-chemical, structural, and spectroscopic information is shown to be a practical method that allows, on one hand, assignment of the observed spectroscopic features to precise structural pathways followed by the photoelectron within the mica structure and, on the other hand, clarification of the amount of electronic interactions and forces acting onto the individual atoms at the various structural sites

Quantitative risk assessment of human salmonellosis from the consumption of typical pork products in the Veneto region of Italy

ARSIS is a pilot scheme commissioned by the Veneto Region aimed at evaluating the risk of salmonellosis for Veneto region mhabitants due to the consumption of \u27insaccati\u27, typical pork sausages. The quantitative nsk assessment (QRA) approach was used to assess the risk of human salmonellosis and to est1mate the number of cases in a year among Veneto inhabitants, divided into sex and age classes

The interlayer structure of trioctahedral lithian micas: An AXANES spectroscopy study at the potassium K-edge

abstra C t We recorded angle-dependent XANES (AXANES) spectra at the potassium K-edge for three compositionally intermediate polylithionite-siderophyllite trioctahedral 1 M-micas using polarized synchrotron radiation. We evaluated the experimental spectra for both their in-plane and out-of-plane component fractions of the electric dipole contribution using the analytical formulae of Brouder (1990), referring to theory to extract the origin of their multiple-scattering pathways of Natoli et al. (2003). This analysis was extended to a fourth lithian mica studied previously and allowed characterization of the local environment and ordering around the potassium atoms in the interlayer of the entire set of micas. The AXANES in-plane components are notably similar to the XANES spectra recorded on randomly oriented powders, provided these are oriented at the "magic angle" (Pettifer et al. 1992). Most observed contributions arise from multiple-scattering interactions of the photoelectron ejected from the potassium absorber colliding with atoms located in the interlayer itself. Note that this includes not only interactions with other coplanar potassium and/or alkali atoms distributed along the interlayer plane, but also with their near- and next-nearest neighboring oxygen atoms which lie on the basal planes of the tetrahedral sheets facing the interlayer. By contrast, the AXANES out-of-plane component suggests that several multiple-scattering pathways cross the energetic and structural barrier represented by the tetrahedral sheets. They reach not only the X anions that are located on the upper level of the octahedral sheets, at the center of the open cavity in the tetrahedral sheet, but also the metal cations centering the octahedral sheet itself. Therefore, the out-of-plane components provide indirect information on the number of independent octahedral sites, the cation oxidation state, and the trans- vs. cis-orientation of the anionic sites

I futuristi alle Esposizioni Biennali Internazionali d'Arte di Venezia (1926-1942)

This research explores the history of the Futurist Group (led by Filippo Tommaso Marinetti) and its involvement in the International Biennale Art Exhibition of Venice between 1926 and 1942. The Futurists involvement during this period was continuous and exhibitors always formed a collective, at times with over thirty artists. The exhibitions in Venice during the 30s took on a major role in the reform of contemporary art events in line with the Fascist regime. This new process aimed, through subsequent selection processes, to open doors at a local level, then on to Rome’s National Quadrennial Exhibition and finally onto the international stage of the Biennale Art Exhibition of Venice where they should have represented the best of Italian art, to be viewed by and compared with foreign nations. The Venetian exhibitions give a privileged viewpoint of not only the various phases of Futurist art and its relationship with art critics of the time, but also the often conflicting and complex relationships between Marinetti’s followers and heads of the Biennale under the forced harmony of the Fascist regime

Fe K-edge X-ray Absorption Spectroscopy of corrosion phases of archaeological iron: results, limitations, and the need for complementary techniques

Data analysis methods for iron X-ray Absorption Spectroscopy (XAS) can provide extensive information about the oxidation state and co-ordination of an Fe-species. However, the extent to which techniques developed using a single-phase iron sample may be applied to complex, mixed-phase samples formed under real-world conditions is not clear. This work uses a combination of pre-edge fitting and linear combination analysis (LCA) to characterise the near edge region of the X-ray absorption spectrum (XANES) for a set of archaeological iron corrosion samples from a collection of cast iron cannon shot excavated from the Mary Rose shipwreck and compares the data with phase compositions determined by Synchrotron X-ray Powder Diffraction (SXPD). Archaeological powder and cross-section samples were compared to a library of iron standards and diffraction data. The XANES are consistent with previous observations that generation of the chlorinated phase akaganeite, β-FeO(OH,Cl), occurs in those samples which have been removed form passive storage and subjected to active conservation. However, the results show that if any metallic species is present in the sample, the contribution from Fe(0) to the spectral region containing a pre-edge for oxidised iron - Fe(II) and Fe(III) - causes the analysis to be less effective and the conclusions unreliable. Consequently, while the pre-edge fitting methodology may be applied to a mixture of iron oxides or oxyhydroxides, the procedure is inappropriate for a mixed metal-oxide sample without the application of a complimentary technique, such as SXPD