Thermally Driven Out-of-Equilibrium Two-Impurity Kondo System

Sierra, Miguel A.,Ló,pez, Rosa,Lim, Jong Soo American Physical Society 2018 Physical review letters Vol.121 No.9

Improving 3D Imagery with Variable Convergence and Focus Accommodation for the Remote Assessment of Fruit Quality

Rafael Sierra,Fumitaka Uchio,Nobukazu Iguchi,Hirokazu Taki 제어로봇시스템학회 2006 제어로봇시스템학회 국제학술대회 논문집 Vol.2006 No.10

Review: Gravitational Vortex Turbines as a Renewable Energy

Jorge Sierra,Alejandro Ruiz,Angie Guevara,Alejandro Posada 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.4

As result of the negative environmental impact of large hydroelectric dams and conventional diesel power plants, new renewable energy sources should be studied. Gravitational Vortex Turbines (GVTs) can provide clean energy to off-grid areas, known as Non-Interconnected Zones in Colombia, by inducing a water vortex in a turbine-generator set. The implementation of these turbines in the world has expanded due to demographic growth in remote areas, and new studies have enhanced their efficiency. However, there is not enough literature about the estimation of the incidence of their geometric and operating parameters on their performance. This paper presents a global overview of GVTs through a literature review that explores their operation as well as numerical, experimental, and analytical studies that have been conducted to improve their efficiency.

Tissue-Material Integration and Biostimulation Study of Collagen Acellular Matrices

Quintero Sierra Lindsey Alejandra,Busato Alice,Zingaretti Nicola,Conti Anita,Biswas Reetuparna,Governa Maurizio,Vigato Enrico,Parodi Pier Camillo,Bernardi Paolo,Sbarbati Andrea,Conti Giamaica 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.3

BACKGROUND: Breast reconstruction after mastectomy using silicone implants is a surgical procedure that occasionally leads to capsular contracture formation. This phenomenon constitutes an important and persistent cause of morbidity, and no successful therapies are available to date. Recently, the use of acellular membranes as a protective material for silicone prostheses has been gaining attention due to their ability to prevent this adverse outcome. For this reason, the evaluation of the tissue-material integration and the induced biostimulation by acellular membranes results crucial. Evaluation of in vivo tissue integration and biostimulation induced by three different natural acellular collagen membranes. METHODS: Scanning electron microscopy was performed to analyse the membrane porosity and cells-biomaterial interaction in vitro, both in dry and wet conditions. Adipose-derived stem cells were cultured in the presence of membranes, and the colonisation capacity and differentiation potential of cells were assessed. In vivo tests and ex vivo analyses have been performed to evaluate dermal integration, absorption degree and biostimulation induced by the evaluated membrane. RESULTS: Analysis performed in vitro on the three different acellular dermal matrices evidenced that porosity and the morphological structure of membranes influence the liquid swelling ratio, affecting the cell mobility and the colonisation capacity. Moreover, the evaluated membranes influenced in different manner the adipose derived stem cells differentiation and their survival. In vivo investigation indicated that the absorption degree and the fluid accumulation surrounding the implant were membrane-dependent. Finally, ex vivo analysis confirmed the membrane-dependent behavior revealing different degree of tissue integration and biostimulation, such as adipogenic stimulation. CONCLUSION: The physico-chemical characteristics of the membranes play a key role in the biostimulation of the cellular environment inducing the development of well-organized adipose tissue.

Ocular Dipping in Creutzfeldt-Jakob Disease

Fernando Sierra-Hidalgo,Sara Llamas,Juan Francisco Gonzalo,Carmen Sánchez Sánchez 대한신경과학회 2014 Journal of Clinical Neurology Vol.10 No.2

Background Ocular dipping (OD), or inverse ocular bobbing, consists of slow, spontaneousdownward eye movements with rapid return to the primary position. It has been mainly reported following hypoxic-ischemic encephalopathy, but has also been described in association withother types of diffuse or multifocal encephalopathies and structural brainstem damage. Case Report We report the case of a previously asymptomatic 66-year-old woman who presented with confusion, recent memory disturbances, and abnormal involuntary movements, followed by a coma. Abnormal spontaneous vertical eye movements consistent with OD developed from the fourth day after admission, and the patient died 20 days later. The pathologicalexamination of the brain confirmed the diagnosis of Creutzfeldt-Jakob disease. Conclusions The precise location of damage causing OD is unknown. In contrast to ocularbobbing, OD has no localizing value itself, but structural brainstem damage is likely when itappears combined with other spontaneous vertical eye movements.

A Proposal for Building the Knowledge Base of Onomasiological Dictionaries

( Gerardo Sierra ),( Laura Hernandez ) 서울대학교 인지과학연구소 2011 Journal of Cognitive Science Vol.12 No.3

In this paper we present a methodology for creating and populating a lexical knowledge base (LKB) to be used in an onomasiological dictionary. The purpose of this methodology is to automatize the creation of specialized onomasiological dictionaries, which help to solve the "tip of the tongue" problem and assist authors in the active linguistic state (encoding). This article includes information about the main architecture of the LKB as well as our proposed dictionary. The methodology presented in this article allows the LKB to be populated with a wide variety of definitions from both colloquial and normative sources in such a way that by employing this LKB these specialized onomasiological dictionaries are able to handle users` queries in natural languages.

A review of formic acid decomposition routes on transition metals for its potential use as a liquid H2 carrier

Schlussel Sierra,Kwon Stephanie 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.11

Formic acid (HCOOH) has emerged as a promising H2 energy carrier due to its reasonable gravimetric and volumetric H2 densities, low toxicity, low flammability, and ease of handling. Its possible productions from biogenic feedstocks also make it an attractive source to produce H2 on demand. The utilization of HCOOH as a liquid H2 carrier requires catalytic systems to selectively dehydrogenate HCOOH at low temperatures without forming CO products that can act as a poison in fuel cell applications. In this review, we summarize the recent progress in understanding HCOOH decomposition via dehydrogenation (to CO2/H2) and dehydration (to CO/H2O) pathways on transition metals, including Cu, Pt, Pd, and Au. The focus is on discussing the surface chemistry of HCOOH reactions on transition metals, including the types of bound intermediates and the identity and kinetic relevance of elementary steps. In doing so, we review current catalyst design strategies for HCOOH dehydrogenation to facilitate the future development of catalytic processes for H2 storage/utilization.

Genetic algorithm with a Bayesian approach for multiple change-point detection in time series of counting exceedances for specific thresholds

Suárez-Sierra Biviana Marcela,Coen Arrigo,Taimal Carlos Alberto 한국통계학회 2023 Journal of the Korean Statistical Society Vol.52 No.4

Although the applications of Non-Homogeneous Poisson Processes (NHPP) to model and study the threshold overshoots of interest in different time series of measurements have proven to provide good results, they needed to be complemented with an efficient and automatic diagnostic technique to establish the location of the change-points, which, when taken into account, make the estimated model fit poorly in regards of the information contained in the real one. Because of this, a new method is proposed to solve the segmentation uncertainty of the time series of measurements, where the generating distribution of exceedances of a specific threshold is the focus of investigation. One of the great contributions of the present algorithm is that all the days that trespassed are candidates to be a change-point, so all the possible configurations of overflow days under the heuristics of a genetic algorithm are the possible chromosomes, which will unite to produce new solutions. Also, such methods will be guarantee to non-local and the best possible one solution, reducing wasted machine time evaluating the least likely chromosomes to be a feasible solution. The analytical evaluation technique will be by means of the Minimum Description Length (MDL) as the objective function, which is the joint posterior distribution function of the parameters of the NHPP of each regime and the change-points that determines them and which account as well for the influence of the presence of said times. Thus, one of the practical implications of the present work comes in terms of overcoming the need of modeling the time series of measurements, where the distributions of exceedances of certain thresholds, or where the counting of certain events involving abrupt changes, is the main focus with applications in phenomena such as climate change, information security and epidemiology, to name a few.

Crack self-healing technology based on bacteria

M.G. Sierra Beltran 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.S1

Concrete cracks due to several reasons and through the cracks oxygen, water, chlorides and other aggressive agents can penetrate, decreasing the concrete durability, performance and life span. Even though concrete has autogenic capacity to heal the cracks, the size of the cracks that can undergo autogenous healing depends on the exposure conditions and remains below 0.6 mm. In order to improve this healing capacity Microbial Induced Precipitation (MIP) has been investigated. This method, which involves the precipitation of calcium carbonate (CaCO3) induced by bacteria, was implemented at Delft University of Technology for the development of self-healing concrete for new structures as well as for mortar and liquid-based systems for repair of existing concrete structures. This paper presents an overview of the materials, their properties and the successful applications in the Netherlands and overseas.

Regional Equilibrium and Migration Patterns in the Americas 1960-2005

Hernan Enriquez Sierra,Jacobo Campo Robledo 한국라틴아메리카학회 2013 라틴아메리카연구 Vol.26 No.4

This paper analyzes the migration dynamics in the Americas from 1960 to 2005 using an equilibrium approach. The migration flow is evaluated using spatial econometrics techniques and controlling for the labor mobility effect and regional wages. Additionally, the estimated model looks for variations in migration by taking into account the distinctive population features in each country, namely the working age population, unemployment rate and relative wages. The estimated model shows that the spatial equilibrium related to net migration is negatively affected by wages and positively influenced by labor supply in the region.