Lepton masses and mixing without Yukawa hierarchies

We investigate the neutrino masses and mixing patten in a version of the $SU(3)_c\otimes SU(3)_L\otimes U(1)_X$ model with one extra exotic charged lepton per family as introduced by Ozer. It is shown that an extended scalar sector, together with a discrete $Z_2$ symmetry, is able to reproduce a consistent lepton mass spectrum without a hierarchy in the Yukawa coupling constants, the former as a carefull balance between one universal see-saw and two radiative mechanisms.Comment: 7 pages, 2 figures, accepted for publication in Phys. Rev. D

A methodology for the generation and non-destructive characterisation of transverse fractures in long bones

Long bone fractures are common and although treatments are highly effective in most cases, it is challenging to achieve successful repair for groups such as open and periprosthetic fractures. Previous biomechanical studies of fracture repair, including computer and experimental models, have simplified the fracture with a flat geometry or a gap, and there is a need for a more accurate fracture representation to mimic the situation in-vivo. The aims of this study were to develop a methodology for generating repeatable transverse fractures in long bones in-vitro and to characterise the fracture surface using non-invasive computer tomography (CT) methods. Ten porcine femora were fractured in a custom-built rig under high-rate loading conditions to generate consistent transverse fractures (angle to femoral axis < 30 degrees). The bones were imaged using high resolution peripheral quantitative CT (HR-pQCT). A method was developed to extract the roughness and form profiles of the fracture surface from the image data using custom code and Guassian filters. The method was tested and validated using artificially generated waveforms. The results revealed that the smoothing algorithm used in the script was robust but the optimum kernel size has to be considered

Directed current due to broken time-space symmetry

We consider the classical dynamics of a particle in a one-dimensional space-periodic potential U(X) = U(X+2\pi) under the influence of a time-periodic space-homogeneous external field E(t)=E(t+T). If E(t) is neither symmetric function of t nor antisymmetric under time shifts $E(t \pm T/2) \neq -E(t)$, an ensemble of trajectories with zero current at t=0 yields a nonzero finite current as $t\to \infty$. We explain this effect using symmetry considerations and perturbation theory. Finally we add dissipation (friction) and demonstrate that the resulting set of attractors keeps the broken symmetry property in the basins of attraction and leads to directed currents as well.Comment: 2 figure

Functional traits driving species role in the structure of terrestrial vertebrate scavenger networks

Species assemblages often have a non-random nested organization, which in vertebrate scavenger (carrion-consuming) assemblages is thought to be driven by facilitation in competitive environments. However, not all scavenger species play the same role in maintaining assemblage structure, as some species are obligate scavengers (i.e., vultures) and others are facultative, scavenging opportunistically. We used a database with 177 vertebrate scavenger species from 53 assemblages in 22 countries across five continents to identify which functional traits of scavenger species are key to maintaining the scavenging network structure. We used network analyses to relate ten traits hypothesized to affect assemblage structure with the “role” of each species in the scavenging assemblage in which it appeared. We characterized the role of a species in terms of both the proportion of monitored carcasses on which that species scavenged, or scavenging breadth (i.e., the species “normalized degree”), and the role of that species in the nested structure of the assemblage (i.e., the species “paired nested degree”), therefore identifying possible facilitative interactions among species. We found that species with high olfactory acuity, social foragers, and obligate scavengers had the widest scavenging breadth. We also found that social foragers had a large paired nested degree in scavenger assemblages, probably because their presence is easier to detect by other species to signal carcass occurrence. Our study highlights differences in the functional roles of scavenger species and can be used to identify key species for targeted conservation to maintain the ecological function of scavenger assemblages.Generalitat Valenciana SEJI/2018/024, APOSTD/2019/016, CIDEGENT/ 2020/030, ACIF/2019/056Ministerio de Educación y Cultura CI-2017-32149, FJCI-2015-25632, IJC2018-036642-I, YC-2019-027216-I, RYC-2015-19231, RYC-2017-2273, GL2012-40013-C02-01/02, CGL2015- 66966-C2-1-R, CGL2015-66966-C2-1-R2, CGL2017-89905-R, RTI2018-099609-B-C21, RTI2018-099609-B-C22Govern de les Illes Balears PD/039/201National Science Centre in Poland 2013/08/M/ NZ9/00469, 2016/22/Z/NZ8/00Slovenian Research Agency P4-0059US Department of Energy DE- EM000439USA National Science Foundation #1255913California Department of Fish & Wildlife P0880013Junta de Andalucía RNM-192

Reabsorción radicular asociada a movimientos ortodóncicos: una revisión de literatura

This literature review about external root resorption linked to orthodontic movements was carried out in 2010 at Universidad Cooperativa de Colombia, Envigado. External root resorption is common as a dental response to an orthodontic treatment. The objective of this paper is to examine the available information through a literature review, regarding this topic in order to have an approach to its development and related factors. A quantitative analysis of external root resorption by traditional radiologic and histological analyses have proven to be inaccurate, hardly to reproduce and technically sensitive. Results of this work suggest different, even contradictory finding with a multifactorial nature for external root resorption, maybe to a fewer number of researches with statistical significance in biochemical field and a growing number of clinical assumptions driven by a post-treatment observation. The application of diverse forces during an orthodontic treatment generates a bone turnover and a root remodeling, even during relapse. Therefore, the orthodontist must understand this process, since it is a common, yet unpredictable complication during treatment. It is required to gather a number of multidisciplinary efforts to approach this topic using systematic analysis and put forward more reliable theories. This will give the orthodontist a greater knowledge to prevent complications and reduce incidence of negative results in dental movement.&nbsp;La presente revisión de literatura acerca de reabsorción radicular externa asociada a movimientos ortodóncicos fue realizada en la Universidad Cooperativa de Colombia, sede Envigado durante el 2010. La reabsorción radicular externa [rre] es una manifestación común de la respuesta dental al tratamiento ortodóncico. El propósito de esta revisión de literatura consiste en abordar la información científica disponible para tener un conocimiento del desarrollo de este proceso y de los factores relacionados con éste. El análisis cuantitativo de la reabsorción radicular externa mediante el uso tradicional de radiografías y análisis histológicos ha demostrado ser impreciso, difícil de reproducir y técnicamente sensible. Los resultados de esta consulta sugieren hallazgos diversos, incluso contradictorios, con un carácter multifactorial para la reabsorción radicular externa, debido posiblemente a un número reducido de investigaciones de significancia estadística en el campo de la investigación bioquímica y a una mayor asociación con creencias de tipo clínico generadas casi todas desde la observación postratamiento. La aplicación de fuerzas variadas durante el tratamiento ortodóncico produce remodelación ósea y conjuntamente remodelado radicular, incluso durante el periodo posortodóncico (recidiva); por ello el ortodoncista debe comprender este proceso ya que es una complicación frecuente pero impredecible dentro del tratamiento. Es necesario un conjunto de esfuerzos multidisciplinarios que aborden el tema con estudios sistemáticos y proporcionen postulados más confiables; esto brindará al ortodoncista un mayor conocimiento del tema, y así podrá evitar las complicaciones y disminuir la incidencia de resultados negativos durante el movimiento dental.&nbsp

Cambio climático en DAPA

Presentación del dr. Andrew Jarvis, director de Decision and Policy Analysis del CIAT, durante la primera Casa Abierta de 2013, dirigida a decanos y docentes

Broken symmetries and directed collective energy transport

We study the appearance of directed energy current in homogeneous spatially extended systems coupled to a heat bath in the presence of an external ac field E(t). The systems are described by nonlinear field equations. By making use of a symmetry analysis we predict the right choice of E(t) and obtain directed energy transport for systems with a nonzero topological charge Q. We demonstrate that the symmetry properties of motion of topological solitons (kinks and antikinks) are equivalent to the ones for the energy current. Numerical simulations confirm the predictions of the symmetry analysis and, moreover, show that the directed energy current drastically increases as the dissipation parameter $\alpha$ reduces. Our results generalize recent rigorous theories of currents generated by broken time-space symmetries to the case of interacting many-particle systems.Comment: 4 pages, 2 figure

The effects of thymoquinone on pancreatic cancer: Evidence from preclinical studies

Thymoquinone (TQ) is a secondary metabolite found in abundance in very few plant species including Nigella sativa L., Monarda fistulosa L., Thymus vulgaris L. and Satureja montana L. Preclinical pharmacological studies have shown that TQ has many biological activities, such as anti-inflammatory, antioxidant and anticancer. Both in vivo and in vitro experiments have shown that TQ acts as an antitumor agent by altering cell cycle progression, inhibiting cell proliferation, stimulating apoptosis, inhibiting angiogenesis, reducing metastasis and affecting autophagy. In this comprehensive study, the evidence on the pharmacological potential of TQ on pancreatic cancer is reviewed. The positive results of preclinical studies support the view that TQ can be considered as an additional therapeutic agent against pancreatic cancer. The possibilities of success for this compound in human medicine should be further explored through clinical trials. © 2022 The Author