Evaluación biomédica de implantes dentales sometidos a cargas oblicuas: combinación de varias características geométricas

Objective: an efficient and simple methodology, based on virtual simulation and computer modelling, for the assessment and evaluation of dental implants design is proposed in this work. Materials and methods: the finite element method, a very common tool in engineering applications, is used for the evaluation the biomechanical performance of the biomedical devices. Von Mises stress is used as the main parameter to assess the suitability of the implant, when it is subjected to functional and biological loading. Also, this work reports the effects on the implant caused by geometrical variations such as length, diameter, thread, cortical bone thickness and abutment inclination. The useful-life of the implant was estimated by performing, in a virtual way, the fatigue tests required by the ISO:14801 standard. Results: for all the analyzed cases, maximum stress was obtained at the connecting screw under oblique loading. The estimated useful-life of the implant was around 5.000.000 cycles, which satisfies both ISO standard and functional requirements. Also, maximum stress was found in the compact-bone tissue surrounding the implant, which is in very good agreement with previous reports. Conclusion: a dental implant with optimal characteristics is proposed and validated using the discussed methodology.Peer ReviewedPostprint (published version

Optimal estimation of high-dimensional unitary transformations

We propose an estimation procedure for $d$-dimensional unitary transformations. For $d>2$, the unitary transformations close to the identity are estimated saturating the quantum Cram\'er-Rao bound. For $d=2$, the estimation of all unitary transformations is also optimal with some prior information. We show through numerical simulations that, even in the absence of prior information, two-dimensional unitary transformations can be estimated with greater precision than by means of standard quantum process tomography.Comment: 8+14 pages, 6 figure

PGF2α (250 mcg d-cloprostenol) Effectiveness of two Schemes for Estrus Induction in Brahman Bovine Females with Lasting Anestrus.

The reproductive behavior of Brahman breeding cows subject to estrus induction was assessed, at the “Rancho Bonito Farm”, Gamelotal area, Lara State, Venezuela. The experiment lasted 90 days, and was based on two estrus induction schemes (Progesterone + Estradiol Benzoate and Progesterone + PMSG). Following 72 h of treatment, 62.5 % of the  cows that received  P4  + PMSG  were fertilized; whereas the P4  + BE treatment induced fertilization of 25 % (P < 0.05). During the 90 days,  93.7 % of the cows that received P4  + PMSG, and 75 %  under  the P4  + BE treatment, were fertilized, which demonstrated the effectiveness of the schemes

Capítulo 2 - El neoinstitucionalismo sociológico como referente para los estudios organizacionales

Desde la década de los setenta del siglo pasado se viene construyendo una nueva propuesta teórica para el abordaje de los fenómenos sociales denominada “neoinstitucionalismo” o “nuevo institucionalismo”. Esta agrupa al reciente conjunto de reflexiones que se interesan por determinar el rol que tienen las instituciones en la vida social. Es notorio entonces que en las distintas áreas del saber social se ha renovado el interés por las instituciones y, en consecuencia, se identifican distintos enfoques del neoinstitucionalismo, tales como el económico, el histórico, el jurídico o normativo, el politológico y el sociológico

Capítulo 4 - Los enfoques de investigación en los estudios organizacionales

Abordar procesos de investigación, desde el campo de los estudios organizacionales, representa un reto para quienes incursionan en esta área, donde resulta indispensable adentrarse en el estudio de los postulados teóricos que subyacen a las teorías administrativas y las teorías organizacionales que dan paso a su inicio, desde una perspectiva multidisciplinaria que intenta comprender los fenómenos, las realidades sociales locales, de una forma mucho más integral

110 Years of Avipoxvirus in the Galapagos Islands

The role of disease in regulating populations is controversial, partly owing to the absence of good disease records in historic wildlife populations. We examined birds collected in the Galapagos Islands between 1891 and 1906 that are currently held at the California Academy of Sciences and the Zoologisches Staatssammlung Muenchen, including 3973 specimens representing species from two well-studied families of endemic passerine birds: finches and mockingbirds. Beginning with samples collected in 1899, we observed cutaneous lesions consistent with Avipoxvirus on 226 (6.3%) specimens. Histopathology and viral genotyping of 59 candidate tissue samples from six islands showed that 21 (35.6%) were positive for Avipoxvirus, while alternative diagnoses for some of those testing negative by both methods were feather follicle cysts, non-specific dermatitis, or post mortem fungal colonization. Positive specimens were significantly nonrandomly distributed among islands both for mockingbirds (San Cristobal vs. Espanola, Santa Fe and Santa Cruz) and for finches (San Cristobal and Isabela vs. Santa Cruz and Floreana), and overall highly significantly distributed toward islands that were inhabited by humans (San Cristobal, Isabela, Floreana) vs. uninhabited at the time of collection (Santa Cruz, Santa Fe, Espanola), with only one positive individual on an uninhabited island. Eleven of the positive specimens sequenced successfully were identical at four diagnostic sites to the two canarypox variants previously described in contemporary Galapagos passerines. We conclude that this virus was introduced late in 1890′s and was dispersed among islands by a variety of mechanisms, including regular human movements among colonized islands. At present, this disease represents an ongoing threat to the birds on the Galapagos Islands

Pentamidine Is Not a Permeant but a Nanomolar Inhibitor of the Trypanosoma brucei Aquaglyceroporin-2

The chemotherapeutic arsenal against human African trypanosomiasis, sleeping sickness, is limited and can cause severe, often fatal, side effects. One of the classic and most widely used drugs is pentamidine, an aromatic diamidine compound introduced in the 1940s. Recently, a genome-wide loss-of-function screen and a subsequently generated trypanosome knockout strain revealed a specific aquaglyceroporin, TbAQP2, to be required for high-affinity uptake of pentamidine. Yet, the underlying mechanism remained unclear. Here, we show that TbAQP2 is not a direct transporter for the di-basic, positively charged pentamidine. Even though one of the two common cation filters of aquaglyceroporins, i.e. the aromatic/arginine selectivity filter, is unconventional in TbAQP2, positively charged compounds are still excluded from passing the channel. We found, instead, that the unique selectivity filter layout renders pentamidine a nanomolar inhibitor of TbAQP2 glycerol permeability. Full, non-covalent inhibition of an aqua(glycero)porin in the nanomolar range has not been achieved before. The remarkable affinity derives from an electrostatic interaction with Asp265 and shielding from water as shown by structure-function evaluation and point mutation of Asp265. Exchange of the preceding Leu264 to arginine abolished pentamidine-binding and parasites expressing this mutant were pentamidine-resistant. Our results indicate that TbAQP2 is a high-affinity receptor for pentamidine. Taken together with localization of TbAQP2 in the flagellar pocket of bloodstream trypanosomes, we propose that pentamidine uptake is by endocytosis