Chaotic image encryption using hopfield and hindmarsh–rose neurons implemented on FPGA

Chaotic systems implemented by artificial neural networks are good candidates for data encryption. In this manner, this paper introduces the cryptographic application of the Hopfield and the Hindmarsh–Rose neurons. The contribution is focused on finding suitable coefficient values of the neurons to generate robust random binary sequences that can be used in image encryption. This task is performed by evaluating the bifurcation diagrams from which one chooses appropriate coefficient values of the mathematical models that produce high positive Lyapunov exponent and Kaplan–Yorke dimension values, which are computed using TISEAN. The randomness of both the Hopfield and the Hindmarsh–Rose neurons is evaluated from chaotic time series data by performing National Institute of Standard and Technology (NIST) tests. The implementation of both neurons is done using field-programmable gate arrays whose architectures are used to develop an encryption system for RGB images. The success of the encryption system is confirmed by performing correlation, histogram, variance, entropy, and Number of Pixel Change Rate (NPCR) tests

A high security double lock and key mechanism in HUH relaxases controls oriT-processing for plasmid conjugation

This is an Open Access article distributed under the terms of the Creative Commons Attribution License.Relaxases act as DNA selection sieves in conjugative plasmid transfer. Most plasmid relaxases belong to the HUH endonuclease family. TrwC, the relaxase of plasmid R388, is the prototype of the HUH relaxase family, which also includes TraI of plasmid F. In this article we demonstrate that TrwC processes its target nic-site by means of a highly secure double lock and key mechanism. It is controlled both by TrwC-DNA intermolecular interactions and by intramolecular DNA interactions between several nic nucleotides. The sequence specificity map of the interaction between TrwC and DNA was determined by systematic mutagenesis using degenerate oligonucleotide libraries. The specificity map reveals the minimal nic sequence requirements for R388-based conjugation. Some nic-site sequence variants were still able to form the U-turn shape at the nic-site necessary for TrwC processing, as observed by X-ray crystallography. Moreover, purified TrwC relaxase effectively cleaved ssDNA as well as dsDNA substrates containing these mutant sequences. Since TrwC is able to catalyze DNA integration in anic-site-containing DNA molecule, characterization of nic-site functionally active sequence variants should improve the search quality of potential target sequences for relaxasemediated integration in any target genome.Spanish Ministry of Science and Innovation [BIO2010-14809 to G.M., BFU2011-26608 to F.C.]; European Union Seventh Framework Programme [612146/FP7-ICT-2013, 282004/FP7-HEALTH.2011.2.3.1-2 to F.C.]. Funding for open access charge: Spanish Ministry of Science and Innovation Grants [BIO2010-14809] and [BFU2011-26608].Peer Reviewe

SPECIFICATION OF A BUSINESS TRAINING MODEL USING THE VIRTUAL CLASSROOM BEFORE COVID-19

Since its inception, the Internet has been a hegemonic factor in academic and professional training, although its use as a tool for information processing has not even been explored. In this sense, the objective of this work was to establish the reliability and validity of an instrument that measured the perception of Internet use. A non-experimental work was carried out with a non-probabilistic selection of 340 students from a public university in central Mexico. The results show a total percentage of variance explained by two perceptual dimensions that allude to the search and selection of information, although the type of design limited the results to the research scenario, suggesting the inclusion of factors related to the beliefs of use of Internet and the provisions as determinants of intentions and the use of digital networks

The diplomacy of water: analysis of case “Río Bravo”

El presente artículo tiene como objetivo describir y comparar, a través de distintos casos, la importancia de la diplomacia del agua en las Relaciones Internacionales. Se analiza la disputa territorial del río Bravo entre México y Estados Unidos a través del Tratado de 1944. Como antecedente, se exponen dos casos de investigación (disputas entre el río Mekong y el Mar de la China Meridional), con el objetivo de sugerir soluciones para futuras problemáticas con base en las investigaciones existentes

Efficacy of melatonin in non-intensive care unit patients with COVID-19 pneumonia and sleep dysregulation

The association of sleep disruption with a higher vulnerability to COVID-19 infection is asubject of major clinical importance. In patients with pneumonia associated with COVID-19admitted to non-intensive care unit (NICU) several factors, like the disrupting influence ofrespiratory distress, medication, greater stress due to social isolation, and lack of appropriateexposure to environmental light can be instrumental to disrupt sleep / wake cycle. Thetherapeutic potential of melatonin to counteract the consequences of COVID-19 infection hasbeen advocated. Because of its wide-ranging effects as an antioxidant, anti-inflammatory, andimmunomodulatory compound, melatonin could be unique in impairing the consequences ofSARS-CoV-2 infection. Melatonin is also an effective chronobiotic agent to reverse the circadiandisruption of social isolation and to control delirium in severely affected patients. Properlyadministered, melatonin may restore the optimal circadian pattern of the sleep-wake cycle andimprove clinical condition in pneumonia associated with COVID-19 patients. The present reviewarticle discusses the importance of maintaining normal sleep and circadian rhythmicity in NICUpatients and provides preliminary data suggesting the efficacy of melatonin (9 mg/day) to reducelength of stay of pneumonia patients associated with COVID-19 in NICU.Fil: Brusco, Luis Ignacio. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cruz, Pablo. No especifíca;Fil: Cangas, Alicia. No especifíca;Fil: González Rojas, Carmen. No especifíca;Fil: Vigo, Daniel Eduardo. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Cardinali, Daniel Pedro. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentin

Voxel model in BNCT treatment planning: Performance analysis and improvements

In recent years, many efforts have been made to study the performance of treatment planning systems in deriving an accurate dosimetry of the complex radiation fields involved in boron neutron capture therapy (BNCT). The computational model of the patient's anatomy is one of the main factors involved in this subject. This work presents a detailed analysis of the performance of the 1 cm based voxel reconstruction approach. First, a new and improved material assignment algorithm implemented in NCTPlan treatment planning system for BNCT is described. Based on previous works, the performances of the 1 cm based voxel methods used in the MacNCTPlan and NCTPlan treatment planning systems are compared by standard simulation tests. In addition, the NCTPlan voxel model is benchmarked against in-phantom physical dosimetry of the RA-6 reactor of Argentina. This investigation shows the 1 cm resolution to be accurate enough for all reported tests, even in the extreme cases such as a parallelepiped phantom irradiated through one of its sharp edges. This accuracy can be degraded at very shallow depths in which, to improve the estimates, the anatomy images need to be positioned in a suitable way. Rules for this positioning are presented. The skin is considered one of the organs at risk in all BNCT treatments and, in the particular case of cutaneous melanoma of extremities, limits the delivered dose to the patient. Therefore, the performance of the voxel technique is deeply analysed in these shallow regions. A theoretical analysis is carried out to assess the distortion caused by homogenization and material percentage rounding processes. Then, a new strategy for the treatment of surface voxels is proposed and tested using two different irradiation problems. For a parallelepiped phantom perpendicularly irradiated with a 5 keV neutron source, the large thermal neutron fluence deviation present at shallow depths (from 54% at 0 mm depth to 5% at 4 mm depth) is reduced to 2% on average. Reassigning fluence values in the case of this phantom in angular position produced the maximum deviation in the thermal fluence to decrease from 140% to 23% at the surface of the phantom. Thus, even for the largest deviations, obtained by intentionally placing the phantom in the most disadvantageous position with respect to the voxel grid, the reassignment shows very good performance. Since these results substantially improve the performance of the 1 cm based voxel model in surface boundary regions, the proposed strategy will be implemented in future versions of the NCTPlan code.Fil: González, Sara Josefina. Comisión Nacional de Energía Atómica; Argentina. United Automobile Insurance Company; ArgentinaFil: Carando, Daniel Germán. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigaciones Matemáticas "Luis A. Santaló". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Matemáticas "Luis A. Santaló"; Argentina. Universidad de San Andrés; ArgentinaFil: Santa Cruz, Gustavo Alberto. Comisión Nacional de Energía Atómica; Argentina. United Automobile Insurance Company; ArgentinaFil: Zamenhof, Robert G.. Tufts-New England Medical Center; Estados Unido

Tourism Development and Sustainability in the community of Caibarién, Cuba

El presente artículo surge de la necesidad de desvelar la influencia del desarrollo turístico en las dimensiones del desarrollo sostenible de la comunidad de Caibarién (Cuba). La información se obtuvo mediante revisión documental y entrevistas semi estructuradas. Los fundamentos teóricos y metodológicos que soportan el tratamiento de este trabajo se estructuran a partir de la producción científica relativa a los temas del desarrollo turístico y el turismo sostenible. Los principales resultados mostraron que la estrategia de desarrollo de Gaviota S.A en los Cayos de Villa Clara, influye indirectamente en la sostenibilidad de la comunidad de Caibarién, lo cual coincide con lo que plantea la literatura académica y presenta su pertinencia también para el caso de Cuba, cuya organización socioeconómica y política se distancia del paradigma neoliberal global. Si bien existen algunas pautas que muestran una tendencia hacia el desarrollo sostenible, aún se identifican aspectos negativos en el modelo de desarrollo turístico que habrán de ser considerados tanto en futuras investigaciones como en sus implicaciones prácticas en la industria turística de Cuba y de otras latitudes.This article arises from the need to reveal the influence of tourism development on the dimensions of sustainable development in the community of Caibarién, Cuba. The information was obtained through documentary review and semi-structured interviews. The theoretical and methodological foundations that support the treatment of the subject are structured from the scientific production related to the topics of tourism development and sustainable tourism. The main results showed that the development strategy of Gaviota SA in the Villa Clara Keys, indirectly influences the sustainability of the Caibarién community, which coincides with what is stated in the academic literature and is also relevant for the case of Cuba, whose socio-economic and political organization distances itself from the global neoliberal paradigm. Although there are elements that show a trend towards sustainable development, negative aspects were still identified as a consequence of the presence of tourism development that will have to be considered both in future research and in its practical implications in the tourism industry of the Island and of other latitudes

A high security double lock and key mechanism in HUH relaxases controls oriT-processing for plasmid conjugation

Relaxases act as DNA selection sieves in conjugative plasmid transfer. Most plasmid relaxases belong to the HUH endonuclease family. TrwC, the relaxase of plasmid R388, is the prototype of the HUH relaxase family, which also includes TraI of plasmid F. In this article we demonstrate that TrwC processes its target nic-site by means of a highly secure double lock and key mechanism. It is controlled both by TrwC-DNA intermolecular interactions and by intramolecular DNA interactions between several nic nucleotides. The sequence specificity map of the interaction between TrwC and DNA was determined by systematic mutagenesis using degenerate oligonucleotide libraries. The specificity map reveals the minimal nic sequence requirements for R388-based conjugation. Some nic-site sequence variants were still able to form the U-turn shape at the nic-site necessary for TrwC processing, as observed by X-ray crystallography. Moreover, purified TrwC relaxase effectively cleaved ssDNA as well as dsDNA substrates containing these mutant sequences. Since TrwC is able to catalyze DNA integration in a nic-site-containing DNA molecule, characterization of nic-site functionally active sequence variants should improve the search quality of potential target sequences for relaxase-mediated integration in any target genome

A hybrid algorithm combining path scanning and biased random sampling for the Arc Routing Problem

The Arc Routing Problem is a kind of NP-hard routing problems where the demand is located in some of the arcs connecting nodes and should be completely served fulfilling certain constraints. This paper presents a hybrid algorithm which combines a classical heuristic with biased random sampling, to solve the Capacitated Arc Routing Problem (CARP). This new algorithm is compared with the classical Path scanning heuristic, reaching results which outperform it. As discussed in the paper, the methodology presented is flexible, can be easily parallelised and it does not require any complex fine-tuning process. Some preliminary tests show the potential of the proposed approach as well as its limitationsPostprint (published version