43 research outputs found
Casimir force in brane worlds: coinciding results from Green's and Zeta function approaches
Casimir force encodes the structure of the field modes as vacuum fluctuations
and so it is sensitive to the extra dimensions of brane worlds. Now, in flat
spacetimes of arbitrary dimension the two standard approaches to the Casimir
force, Green's function and zeta function, yield the same result, but for brane
world models this was only assumed. In this work we show both approaches yield
the same Casimir force in the case of Universal Extra Dimensions and
Randall-Sundrum scenarios with one and two branes added by p compact
dimensions. Essentially, the details of the mode eigenfunctions that enter the
Casimir force in the Green's function approach get removed due to their
orthogonality relations with a measure involving the right hyper-volume of the
plates and this leaves just the contribution coming from the Zeta function
approach. The present analysis corrects previous results showing a difference
between the two approaches for the single brane Randall-Sundrum; this was due
to an erroneous hyper-volume of the plates introduced by the authors when using
the Green's function. For all the models we discuss here, the resulting Casimir
force can be neatly expressed in terms of two four dimensional Casimir force
contributions: one for the massless mode and the other for a tower of massive
modes associated with the extra dimensions.Comment: 30 pages, title, abstract and discussion have change
Anti-tumoural activity of the G-quadruplex ligand pyridostatin against BRCA1/2-deficient tumours
BRCA2; DNA damage responses; PyridostatinBRCA2; Respostes al dany de l'ADN; PiridostatinaBRCA2; Respuestas al daño del ADN; PiridotatinaThe cells with compromised BRCA1 or BRCA2 (BRCA1/2) function accumulate stalled replication forks, which leads to replication-associated DNA damage and genomic instability, a signature of BRCA1/2-mutated tumours. Targeted therapies against BRCA1/2-mutated tumours exploit this vulnerability by introducing additional DNA lesions. Because homologous recombination (HR) repair is abrogated in the absence of BRCA1 or BRCA2, these lesions are specifically lethal to tumour cells, but not to the healthy tissue. Ligands that bind and stabilise G-quadruplexes (G4s) have recently emerged as a class of compounds that selectively eliminate the cells and tumours lacking BRCA1 or BRCA2. Pyridostatin is a small molecule that binds G4s and is specifically toxic to BRCA1/2-deficient cells in vitro. However, its in vivo potential has not yet been evaluated. Here, we demonstrate that pyridostatin exhibits a high specific activity against BRCA1/2-deficient tumours, including patient-derived xenograft tumours that have acquired PARP inhibitor (PARPi) resistance. Mechanistically, we demonstrate that pyridostatin disrupts replication leading to DNA double-stranded breaks (DSBs) that can be repaired in the absence of BRCA1/2 by canonical non-homologous end joining (C-NHEJ). Consistent with this, chemical inhibitors of DNA-PKcs, a core component of C-NHEJ kinase activity, act synergistically with pyridostatin in eliminating BRCA1/2-deficient cells and tumours. Furthermore, we demonstrate that pyridostatin triggers cGAS/STING-dependent innate immune responses when BRCA1 or BRCA2 is abrogated. Paclitaxel, a drug routinely used in cancer chemotherapy, potentiates the in vivo toxicity of pyridostatin. Overall, our results demonstrate that pyridostatin is a compound suitable for further therapeutic development, alone or in combination with paclitaxel and DNA-PKcs inhibitors, for the benefit of cancer patients carrying BRCA1/2 mutations.Research in A.B. laboratory is supported by grants of Italian Association for Cancer Research (AIRC # 21579), Ministry of Health (CO 2019-12369662) and from IRCCS-Regina Elena Cancer Institute. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 722729 (F.J.G.). Research in M.T. laboratory is supported by Cancer Research UK (DRCPGM\100001), Medical Research Council and University of Oxford. A.R. received support from the UK Medical Research Council grant MC_PC_12006. V.S. received support from Instituto de Salud Carlos III (CPII19/00033, PI17/01080), GHD pink and the FERO Foundation
Advanced Exergy Analysis of an Integrated SOFC-Adsorption Refrigeration Power System
In this chapter, an exergy analysis applied to a solid oxide fuel cell (SOFC)/vapor adsorption refrigeration (VAR) system is presented. The influences of four significant parameters (current density, inlet fuel temperature, fuel utilization and steam-to-carbon ratio) on the exergy efficiency of both the SOFC stack and the SOFC-VAR system are investigated. In order to do so, a mathematical model is constructed in Engineering Equation Solver (EES) software to generate the simulations. The analysis shows that the calculated exergy efficiency is around 8% lower than the energy efficiency for both cases. Moreover, it is found that most of the causes of irreversibilities in the system are due to electronic and ionic conduction in the components. It is also shown that the exergy efficiency is substantially sensitive to fuel inlet temperature, which is evidenced by a bending-over behavior. Finally, in accordance with the calculated efficiency defects, the main exergy destructions are present in the heat exchangers, the SOFC, the afterburner and the generator
Casimir effect in a six-dimensional vortex scenario
Recently Randjbar-Daemi and Shaposhnikov put forward a 4-dimensional
effective QED coming from a Nielsen-Olesen vortex solution of the abelian Higgs
model with fermions coupled to gravity in D=6. However, exploring possible
physical consequences of such an effective QED was left open. In this letter we
study the corresponding effective Casimir effect. We find that the extra
dimensions yield fifth and third inverse powers in the separation between
plates for the modified Casimir force which are in conflict with known
experiments, thus reducing the phenomenological viability of the model.Comment: 12 pages, references added, comparison with experimental data
clarified. v4 published versio
Cyber ​​Crimes in Chile, Mexico and Colombia. A Comparative Law Study
Chile, MĂ©xico y Colombia han hecho grandes esfuerzos para tipificar las conductas relacionadas con los delitos cibernĂ©ticos, pero, aquĂ surge una cuestiĂłn, quĂ© tanto han avanzado en las reformas constitucionales y legales sobre dicha materia. Para ello, necesitamos un referente, por lo que, consideramos que pudiera servirnos de parámetro el Convenio creado por el Consejo de Europa sobre Ciberdelincuencia celebrado en Budapest en el año de 2001; pues se trata de un acuerdo internacional para combatir el crimen organizado transnacional, especĂficamente por lo que se refiere a los delitos informáticos; su principal objetivo es crear una legislaciĂłn penal sustantiva y adjetiva aplicable en todos los Estados Partes.El objetivo de este artĂculo fue investigar y analizar los delitos cibernĂ©ticos vigentes en Chile, MĂ©xico y Colombia, con el fin, primero, de estudiar sus ordenamientos jurĂdicos tendientes a regular estas nuevas formas delictivas; segundo, conocer cuáles son las semejanzas y diferencias que guardan los delitos cibernĂ©ticos en los tres paĂses; por Ăşltimo, determinar si en los inicios de la tercera dĂ©cada del siglo XXI, los tres paĂses han adecuado su marco constitucional y legal a los tĂ©rminos establecidos en el Convenio sobre la Ciberdelincuencia 2001, celebrado en Budapest
Quantitative HBsAg an unreliable marker for diagnosis and disease progression in genotype F chronic HBeAg-negative infections
Quantitative hepatitis B surface antigen (qHBsAg) has been proposed as a biomarker to distinguish HBeAg-negative chronic infections (ENI) from HBeAg-negative chronic hepatitis (ENH), identify patients prone to achieving sustained HBsAg loss, and predict the risk of liver disease progression. There is evidence that qHBsAg varies among genotypes, however there is a paucity of data on genotype F. The aim of this study was to investigate the performance of qHBsAg in the diagnosis and evolution of genotype F chronic HBeAg-negative infections. HBV-DNA and HBsAg levels from 153 patients with ENI were correlated with the genotype. Liver disease progression was assessed by abdominal ultrasound and a transient elastography. The qHBsAg levels were significantly different among genotypes (p 3.0 log10 IU/ml, no cases of advanced liver disease were observed at the end of follow-up. This study provides new insights into the impact of HBV genotypes, in particular GTF, on serum HBsAg levels, emphasizing the need to implement a genotype-specific cut-off to achieve diagnostic certainty in the identification of ENI and the risk of liver disease progression. Regardless of HBV genotype, qHBsAg has been shown to be a powerful and reliable biomarker for predicting HBsAg loss.Fil: Fainboim, Hugo. Gobierno de la Ciudad de Buenos Aires. Hospital de Infecciosas "Dr. Francisco Javier Muñiz"; ArgentinaFil: Di Benedetto, Nicolas. Hospital Arrecifes; ArgentinaFil: Paz, Silvia. Gobierno de la Ciudad de Buenos Aires. Hospital de Infecciosas "Dr. Francisco Javier Muñiz"; ArgentinaFil: Mendizabal, Manuel. Universidad Austral; ArgentinaFil: Campuzano, Soledad. Gobierno de la Ciudad de Buenos Aires. Hospital de Infecciosas "Dr. Francisco Javier Muñiz"; ArgentinaFil: Elizalde, Maria Mercedes. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de Investigaciones BiomĂ©dicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones BiomĂ©dicas en Retrovirus y Sida; ArgentinaFil: Tadey, Luciana. Gobierno de la Ciudad de Buenos Aires. Hospital de Infecciosas "Dr. Francisco Javier Muñiz"; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Deluchi, Gabriel. Gobierno de la Ciudad de Buenos Aires. Hospital de Infecciosas "Dr. Francisco Javier Muñiz"; ArgentinaFil: Bouzas, MarĂa BelĂ©n. Gobierno de la Ciudad de Buenos Aires. Hospital de Infecciosas "Dr. Francisco Javier Muñiz"; ArgentinaFil: Mammana, Lilia. Gobierno de la Ciudad de Buenos Aires. Hospital de Infecciosas "Dr. Francisco Javier Muñiz"; ArgentinaFil: Flichman, Diego Martin. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de Investigaciones BiomĂ©dicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones BiomĂ©dicas en Retrovirus y Sida; Argentin
Estado del conocimiento del estudio sobre mezclas asfálticas modificadas en Colombia
En el mundo, la tecnologĂa de los asfaltos modificados ha sido una tĂ©cnica ampliamente utilizada para mejorar las caracterĂsticas que presentan las mezclas asfálticas convencionales cuando son sometidas a niveles elevados de tránsito y de gradientes de temperatura. En Colombia, los desarrollos investigativos en el área de los asfaltos y las mezclas asfálticas modificadas son extensos en comparaciĂłn con la cantidad de estructuras de pavimentos flexibles construidas con esta tecnologĂa. El artĂculo presenta el estado del conocimiento de los estudios que han desarrollado diversos grupos e instituciones de investigaciĂłn en el área de los asfaltos y las mezclas asfálticas modificadas en Colombia
Impact of chronic stress protocols in learning and memory in rodents: systematic review and meta-analysis
The idea that maladaptive stress impairs cognitive function has been a cornerstone of decades in basic and clinical research. However, disparate findings have reinforced the need to aggregate results from multiple sources in order to confirm the validity of such statement. In this work, a systematic review and meta-analyses were performed to aggregate results from rodent studies investigating the impact of chronic stress on learning and memory. Results obtained from the included studies revealed a significant effect of stress on global cognitive performance. In addition, stressed rodents presented worse consolidation of learned memories, although no significantly differences between groups at the acquisition phase were found. Despite the methodological heterogeneity across studies, these effects were independent of the type of stress, animals' strains or age. However, our findings suggest that stress yields a more detrimental effect on spatial navigation tests' performance. Surprisingly, the vast majority of the selected studies in this field did not report appropriate statistics and were excluded from the quantitative analysis. We have therefore purposed a set of guidelines termed PROBE (Preferred Reporting Orientations for Behavioral Experiments) to promote an adequate reporting of behavioral experiments.This work was funded by the European Commission (FP7) "SwitchBox" (Contract HEALTH-F2-2010-259772) project and co-financed by the Portuguese North Regional Operational Program (ON.2 - O Novo Norte) under the National Strategic Reference Framework (QREN), through the European Regional Development Fund (FEDER), and by Fundacao Calouste Gulbenkian (Portugal) (Contract grant number: P-139977; project "Better mental health during ageing based on temporal prediction of individual brain ageing trajectories (TEMPO)"). PSM is supported by an FCT fellowship grant, from the PhD-iHES program, with the reference PDE/BDE/113601/2015.info:eu-repo/semantics/publishedVersio
Non-linear modal analysis methods for engineering structures
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