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Shape and deformation of the Pampean flat slab in Argentina
(2025-10-16) Linkimer Abarca, Lepolt; Warren, Linda M.; Chang, Ying; Anderson, Megan L.; Beck, Susan L.; Olsen, Kira G.
The dominant forces shaping the unique geometries of flat slabs are still not fully understood. Knowing how the stress field changes with respect to the shape of the slab allows inferences of the dominant forces acting on the slab. In this study we calculated new models of the slab geometry and the intraslab stress field in the Pampean flat slab region of the Chile-Argentina Subduction Zone (latitude ∼25◦36◦S) where the Nazca Plate subducts together with the aseismic Juan Fernandez Ridge. To build the models, we used a catalogue of 1 059 well-located slab earthquakes recorded by the SIEMBRA and ESP temporary seismic arrays and calculated 411 new focal mechanisms that were analysed together with 407 focal mechanisms from other catalogues. Our results confirmed slab seismicity features such as a reverse dip (i.e. opposite to the subduction direction) of the seismicity band within the flat slab, two bands of descending seismicity and two regions with an absence of earthquakes. These seismicity patterns express the shape of the slab and its hydration state, with more localized slab dehydration along the inland path of the Juan Fernandez Ridge relative to the surroundings. In one of the regions without earthquakes, the slab is most likely continuous and dry, while in the other one the slab is missing, in agreement with previous works that proposed a hole in the slab visible with other methods. A comparison between the stress field and the local slab dip from both our new model and a previous one (Slab2) indicates that the dominant forces acting on the flat slab are the slab pull and the ridge buoyancy. Finally, the shape of the flat slab is controlled by the geologic migration of the Juan Fernandez Ridge, making the flat slab four times wider than the ridge offshore, and by the competing forces of the slab pull and the ridge buoyancy that creates a notable flexure (bulge) resembling the geometry of the outer rise near the trench.
Huygens and π
(2025-11) Villarino, Mark Bertram; Várilly Boyle, Joseph C.
The Dutch scientist Christiaan Huygens refined Archimedes' celebrated geometrical computation of π to its highest point. Yet the rich content of his beautiful treatise "De circuli magnitudine inventa" (1654) has apparently never been presented in modern form. Here we offer a detailed and contemporary development of several of his most striking results. We also make a historical conjecture concerning Archimedes' trisection figure.
The full electroweak interaction: An autonomous account
(2025-02-18) Gracia Bondía, José Mariano; Rehren, Karl Henning; Várilly Boyle, Joseph C.
The precise renormalizable interactions in the bosonic sector of electroweak theory are intrinsically determined in the autonomous approach to perturbation theory. This proceeds directly on the Hilbert-Fock space built on the Wigner unirreps of the physical particles, with their given masses: those of three massive vector bosons, a photon, and a massive scalar (the "higgs"). Neither "gauge choices" nor an unobservable "mechanism of spontaneous symmetry breaking" is invoked. Instead, to proceed on Hilbert space requires using string-localized fields to describe the vector bosons. In such a framework, the condition of string independence of the S-matrix yields consistency constraints on the coupling coefficients, the essentially unique outcome being the experimentally known one. The analysis can be largely carried out for other configurations of massive and massless vector bosons, paving the way towards consideration of consistent mass patterns beyond those of the electroweak theory.
Genetic transformation of orchids
(2025-11-04) Viswanath, Kasi K.; Huang, Jian-Zhi; Bolaños Villegas, Pablo; Chen, Fure-Chyi
Orchids are prized for their beautiful flowers, but traditional breeding takes time and may not quickly produce new varieties. Genetic transformation can help, though different genera react differently to methods like biobalistics and transfection by Agrobacterium tumefaciens. This review examines the pros and cons of these techniques and necessary adjustments, such as adding acetosyringone, chemicals to induce sensitivity to A. tumefaciens, selecting vectors, and choosing appropriate explant tissue for transformation. We hope thus to aid research teams across the world in creating innovative traits to meet market demand.
Design, development and preclinical assessment of MENAVip-ICP, a new snake antivenom with potential coverage of species in the Middle East and North Africa regions
(2024-12) Segura Ruiz, Álvaro; Moscoso Suárez, Edwin; Umaña Blanco, Deibid; Vargas Arroyo, Mariángela; Sánchez Brenes, Andrés; Hernández Bolaños, Andrés; Durán Blanco, Gina; Villalta Arrieta, Mauren; Gómez Arguello, Aarón; Herrera Vega, María; Arguedas Gómez, Mauricio; Gutiérrez, José María; León Montero, Guillermo
Snakebite in the Middle East and North Africa (MENA) is a public health problem whose magnitude is not fully known. Several antivenoms are available in these regions, but these formulations are designed for restricted geographical settings. Many countries do not have local production of antivenoms and must access products whose clinical performance has not been demonstrated. We hypothesize that it is possible to unify the treatment for viperid snakebites of MENA in a single antivenom formulation. Hereby we describe the design, development and preclinical evaluation of an antivenom of broad geographical coverage for this region (MENAVip-ICP). We produced this antivenom from the plasma of horses immunized with eight medically important venoms of viperid snake species from MENA. For this, we used a strategy based on two stages: first, immunization of horses with North African (NA) venoms, followed by a second immunization stage, on the same horses, with MENA venoms. We purified antivenoms from both stages: the Anti-NA and the final product Anti-MENA (MENAVip-ICP). Anti-NA was considered as intermediate formulation and was purified with the intention to study the progression of the immunoglobulin immune response of the horses. Antivenoms from both stages neutralized lethal, hemorrhagic, and procoagulant activities of homologous venoms. Compared to Anti-NA, MENAVip-ICP improved the neutralization profile of intravenous lethality and in vitro procoagulant activities of venoms. A notable finding was the difference in the neutralization of lethality when MENAVip-ICP was assessed intraperitoneally versus intravenously in the murine model. Intraperitoneally, MENAVip-ICP appears more effective in neutralizing the lethality of all venoms. Furthermore, MENAVip-ICP neutralized the lethal activity of venoms of species from other regions of MENA, Central/East Asia, and Sub-Saharan Africa that were not included in the immunization protocol. Our results showed that MENAVip-ICP neutralizes the main toxic activities induced by viperid MENA venoms at the preclinical level. Consequently, it is a promising product that could be clinically assessed for the treatment of snakebite envenomings in this region.