First record of the sound produced by the oldest Upper Paleolithic seashell horn

Anthropologists and ethnomusicologists assert that there is no society without song, and more specifically, there is no ritual or celebration without accompanying sound. The production of sounds in social contexts is very ancient. Here, we report on the study of a seashell from the decorated cave of Marsoulas and demonstrate that the Magdalenian occupants of this site transformed this shell into a wind instrument. It is one of the very rare examples, if not the only one for the Paleolithic period, of a musical instrument fashioned from a large shell, and the first conch shell of this use thus far discovered. We already know that prehistoric people transformed many shells into portable ornaments and that they thus attributed substantial corporal symbolism to them. This seashell horn, with its unique sonority, both deep and strong with an enduring reverberation, sheds light on a musical dimension until now unknown in the context of Upper Paleolithic societies.

Structural Modelling, Construction and Test of The First 3D-printed Gridshell in Ice Composite

In the past, record breaking large shell structures with ice composites were successfully realized by spraying cellulose-water mixture on an inflatable mould. This paper presents the application of a new, production technique for ice composites by extrusion instead of spraying. With this additive manufacturing technique, the world's first gridshell in fibre-reinforced ice was designed, constructed, and tested. To increase the stiffness of the gridshell the floorplan of the inflatable mould was designed with an anti-clastic curvature at the supports of the structure. Concerning the pattern of the grid different options were developed and compared and verified in ABAQUS®. The size of the struts were determined by an iterative process. The gridshell was realized in a cold environment by printing multiple layers of cellulose-water mixture on the inflatable mould using piping bags. After the substance has been extruded, the mixture froze at temperatures of minus eight degrees Celsius or lower. The realized structure was tested on-site with a dead load to prove its strength.

Type synthesis of 90°/180° dual-function upenders for large shell units of nuclear reactor

In this paper, unit vectors collinear with the axes of large shell units of nuclear reactors were used to represent the poses of the workpieces. Based on the motion operator interpretation of the rotation matrix, 60 kinds of rotation matrix permutations with 90° turns as the step length to achieve 180° flipping of the workpiece were obtained. After eliminating invalid permutations and merging homogenous permutations, class I, II, and III flipping motion models were obtained. By calculating the Lie algebra of each step of rigid body motion in the flipping motion model, the twist and the motion pair property for each step were obtained. By means of the permutation and combination theory, the sequence of the motion pairs for different configurations was determined, and the rules between sequential transformations and axis changes of the motion pairs under the initial configuration were stipulated. Three classes of 19 initial configurations of 90°/180° dual-function upenders were constructed. For three of them, taking into account the characteristics of the axial dimension variation of workpieces, prismatic pairs were added along the workpiece’s axis (vector), and 15 overall configurations of 90°/180° dual-function upenders were synthesized. This provides the basic theoretical support for the innovative design of upenders with independent intellectual property rights.

Runaways and shells around the CMa OB1 association

Context. The origin of the arc-shaped Sh 2-296 nebula is still unclear. Mainly due to its morphology, the nebula has been suggested to be a 0.5 Myr old supernova remnant (SNR) that could be inducing star formation in the CMa OB1 association. This means that the region might be an excellent laboratory for investigating the influence of massive stars on their surroundings. Aims. We aim to show for the first time that the nebula is part of a large shell-like structure, which we have designated the “CMa shell”, enclosing a bubble created by successive supernova (SN) explosions. We identify three runaway stars, associated with bow-shock structures, in the direction of the CMa shell, and we investigate the possibility that they have originated in the center of the shell. Methods. By analyzing images of the CMa OB1 association at several wavelengths, we clearly saw that the Sh 2-296 nebula is in fact part of a large structure that can be approximated by a large elliptical shell (with a diameter of ~60 pc). Using the recent Gaia DR2 astrometric data, we traced back the path of the three runaway stars, in order to determine their original position in the past, with relation to the CMa shell. We also revised the heating and ionization of the Sh 2-296 nebula by comparing the photon budget provided by the O stars in the region with results from radio observations. Results. We find that the runaway stars have likely been ejected from a Trapezium-like progenitor cluster on three successive SN explosions that occurred ~6, ~2 and ~1 Myr ago. We also show that the few late-type O stars in the region cannot explain the ionization of the Sh 2-296 nebula, and that other mechanisms need to be at work. Conclusions. We argue that although we now have evidence for several SNe events in the CMa OB1 association, the SNe probably played a minor role in triggering star formation in these clouds. In contrast, the CMa OB1 association as it is now likely testifies to the last stages of a star-forming region.

Evolution of thin shells in D-dimensional general relativity

In this paper, we consider singular timelike spherical hypersurfaces embedded in a [Formula: see text]-dimensional spherically symmetric bulk spacetime which is an electrovacuum solution of Einstein equations with cosmological constant. We analyze the different possibilities regarding the orientation of the gradient of the standard [Formula: see text] coordinate in relation to the shell. Then we study the dynamics according to Einstein equations for arbitrary matter satisfying the dominant energy condition. In particular, we thoroughly analyze the asymptotic dynamics for both the small and large-shell-radius limits. We also study the main qualitative aspects of the dynamics of shells made of linear barotropic fluids that satisfy the dominant energy condition. Finally, we prove weak cosmic censorship for this class of solutions.

A morphological gap for Iberian Zospeum filled: Zospeum percostulatum sp. n. (Gastropoda, Eupulmonata, Carychiidae) a new species from Asturias (Spain)

Zospeumpercostulatumsp. n. from Cueva de La Herrería (Llanes, Asturias) is described. It is characterized by a relatively large shell (1.4–1.8 mm height), conical, with ovate aperture, continuous peristome and thickened parietal callus; shell costulate except two first whorls; without any sort of inner formations. It is the first clearly costulate Iberian species, filling a morphological gap in the Iberian clade, and the largest species from the Cantabrian region, being the first species described from Asturias.