alejandra hernandez rojas - Academia.edu (original) (raw)

Papers by alejandra hernandez rojas

2022 IEEE International Conference on Image Processing (ICIP)

Seismic acquisition is important in the exploration of the subsurface to find new petroleum field... more Seismic acquisition is important in the exploration of the subsurface to find new petroleum fields, where a regularspaced dense acquisition is critical to obtain high-quality seismic images. However, the acquisition costs and environmental impacts have motivated undersampled acquisition schemes, where several sensing points are removed to decrease the total seismic sources. After the undersampled measurements are acquired, a recovery algorithm reconstructs the missing seismic images (shots). The removed sources are currently selected using random sensing schemes, leading to suboptimal quality in the recovered seismic images. Thus, an optimal design of the removed sources is crucial as it determines the quality of the recovered shots. This work proposes an end-to-end optimization to jointly design undersampled seismic acquisition geometries while preserving the highquality of the reconstructed data. The seismic acquisition geometry is modeled as a deep binary layer to learn the optimal sensing pattern, while a deep neural network is used to recover the underlying removed shots. Extensive simulations were carried out on a realistic-synthetic Foothills model. The results obtained on the reconstructed data validate that the proposed acquisition design outperforms the state-of-the-art random, uniform, and jitter sensing schemes in 4 dB.

Imaging and Applied Optics Congress 2022 (3D, AOA, COSI, ISA, pcAOP)

This paper proposes a probabilistic regularization for joint optimization of optical coding and r... more This paper proposes a probabilistic regularization for joint optimization of optical coding and recovery for compressive imaging. We regularize the probability distribution of the compressive measurement to improve the decoder network performance.

International Journal of Environmental Research and Public Health

The accreditation process of primary healthcare centers in Chile has not had the same progress as... more The accreditation process of primary healthcare centers in Chile has not had the same progress as in hospitals, which show high levels of compliance. The purpose of this research is to characterize the communes that have accredited family healthcare centers (CESFAMs) through socio-economic, municipal management, clinical management, and population variables by performing a principal components analysis (PCA) with biplot analysis and a grouping of communes through a hierarchical analysis. The biplot analysis and hierarchical analysis yielded the formation of three large groups of communes with accredited CESFAMs, characterized mainly by population size, number of people registered in the municipal health system, socioeconomic indicators, and financial management and clinical management variables. It was found that the communes that have accredited CESFAMs are characterized by dissimilar behavior in relation to the variables analyzed. Through the model used, it was possible to establi...

Journal of Ethics in Entrepreneurship and Technology

Purpose The emergence of artificial intelligence (AI) is leading to a job transformation within t... more Purpose The emergence of artificial intelligence (AI) is leading to a job transformation within the service ecosystem in which issues related to AI governance principles may hinder the social sustainability of the sector. The relevance of AI startups in driving innovation has been recognized; thus, this paper aims to investigate whether and how AI startups may influence the sustainable social development (SSD) of the service sector. Design/methodology/approach An empirical study based on 24 in-depth interviews was conducted to qualitatively explore the perceptions of service sector facing AI policymakers, AI consultants and academics (n = 12), as well as AI startups (founders, AI developers; n = 12). An inductive coding approach was used to identify and analyze the data. Findings As part of a complex system, AI startups influence the SSD of the service sector in relation to other stakeholders’ contributions for the ethical deployment of AI. Four key factors influencing AI startups’ ...

International Journal of Environmental Research and Public Health, 2021

The Public Health Service in Chile consists of different levels of complexity and coverage depend... more The Public Health Service in Chile consists of different levels of complexity and coverage depending on the severity and degree of specialization of the pathology to be treated. From primary to tertiary care, tertiary care is highly complex and has low coverage. This work focuses on an analysis of the public health system with emphasis on the healthcare network and tertiary care, whose objectives are designed to respond to the needs of each patient. A review of the literature and a field study of the problem of studying the perception of internal and external users is presented. This study intends to be a contribution in the detection of opportunities for the relevant actors and the processes involved through the performance of Triage. The main causes and limitations of the excessive use of emergency services in Chile are analyzed and concrete proposals are generated aiming to benefit clinical care in emergency services. Finally, improvements related to management are proposed and t...

Engineering Geology, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Boletín de Geología, 2021

Los movimientos en masa son la amenaza natural más frecuente en zonas tropicales y son causantes ... more Los movimientos en masa son la amenaza natural más frecuente en zonas tropicales y son causantes de graves daños en la infraestructura vial, pérdida de vidas humanas y consecuencias económicas. Por lo tanto, una evaluación cuantitativa y confiable de la susceptibilidad por movimientos en masa es esencial para el desarrollo y planeación territorial. En este trabajo se estudia el cálculo de la susceptibilidad con un bajo nivel de incertidumbre a partir de la integración metodológica de Pesos de Evidencia con las Redes Neuronales Artificiales. El primero se usó para extraer los valores de los pesos de las variables y el inventario de movimientos en masa, y el segundo para establecer una relación no lineal entre los factores condicionantes y el inventario puntual de movimientos en masa realizado a partir del estudio geológico y geomorfológico del municipio de Popayán. Esto genera una doble verificación que permite extraer las características de las variables categóricas y continuas para...

Water Science and Technology, 2004

Computer modelling has been used in the last 15 years as a powerful tool for understanding the be... more Computer modelling has been used in the last 15 years as a powerful tool for understanding the behaviour of activated sludge wastewater treatment systems. However, computer models are mainly applied for domestic wastewater treatment plants (WWTPs). Application of these types of models to industrial wastewater treatment plants requires a different model structure and an accurate estimation of the kinetics and stoichiometry of the model parameters, which may be different from the ones used for domestic wastewater. Most of these parameters are strongly dependent on the wastewater composition. In this study a modified version of the activated sludge model No. 1 (ASM 1) was used to describe a tannery WWTP. Several biological tests and complementary physical-chemical analyses were performed to characterise the wastewater and sludge composition in the context of activated sludge modelling. The proposed model was calibrated under steady-state conditions and validated under dynamic flow cond...

Journal of clinical microbiology, Jan 18, 2018

Yellow fever (YF) is the prototypical hemorrhagic fever and results from infection with Yellow Fe... more Yellow fever (YF) is the prototypical hemorrhagic fever and results from infection with Yellow Fever Virus (YFV), which is endemic to regions of Africa and South America. Despite the availability of an effective vaccine, YFV continues to cause disease throughout endemic regions, including intermittent large outbreaks among under-vaccinated populations. A number of diagnostic methods and assays have been described for the detection of YFV infection, including viral culture, molecular testing, serology, and antigen detection. Commercial diagnostics are not widely available, and testing is generally performed at a small number of reference laboratories. The goal of this article, therefore, is to review available clinical diagnostics for YFV, which may not be familiar to many practitioners outside of endemic areas. Additionally, we identify gaps in our current knowledge about YF that pertain to diagnosis and describe interventions that may improve YFV detection.

The American journal of tropical medicine and hygiene, Jan 2, 2018

The differential diagnosis of dengue virus (DENV) and yellow fever virus (YFV) infections in ende... more The differential diagnosis of dengue virus (DENV) and yellow fever virus (YFV) infections in endemic areas is complicated by nonspecific early clinical manifestations. In this study, we describe an internally controlled, multiplex real-time reverse transcription PCR (rRT-PCR) for the detection of DENV and YFV. The DENV-YFV assay demonstrated specific detection and had a dynamic range of 2.0-8.0 log copies/μL of eluate for each DENV serotype and YFV. Clinical performance was similar to a published pan-DENV assay: 48/48 acute-phase samples from dengue cases were detected in both assays. For YFV detection, mock samples were prepared with nine geographically diverse YFV isolates over a range of concentrations. The DENV-YFV assay detected 62/65 replicates, whereas 54/65 were detected using a reference YFV rRT-PCR. Given the reemergence of DENV and YFV in areas around the world, the DENV-YFV assay should be a useful tool to narrow the differential diagnosis and provide early case detection.

Vector borne and zoonotic diseases (Larchmont, N.Y.), May 13, 2018

Alphaviruses can produce febrile illness and encephalitis in dead-end hosts such as horses and hu... more Alphaviruses can produce febrile illness and encephalitis in dead-end hosts such as horses and humans. Within this genus, the Venezuelan Equine Encephalitis virus (VEEV) complex includes pathogenic epizootic subtypes and enzootic subtypes that are not pathogenic in horses (except subtype IE, Mexican strains), although they can cause febrile symptoms in humans. The Rio Negro virus (RNV-VEEV subtype VI) circulates in Argentina, where it was associated with undifferentiated febrile illness. Mayaro (MAYV) and Una (UNAV) viruses belong to a different group, the Semliki Forest virus complex, with confirmed circulation. The present study aimed to determine RNV, MAYV, and UNAV seroprevalences by plaque reduction neutralization test in 652 samples of Paraguayan individuals mainly from the Central Department, between years 2012 and 2013. Samples with antibodies titer >1:20 against RNV were also tested for Mosso das Pedras-subtype IF, subtype IAB, and Pixuna (PIXV)-subtype IV viruses that b...

Journal of clinical virology : the official publication of the Pan American Society for Clinical Virology, Jan 21, 2017

Mayaro virus (MAYV) causes an acute febrile illness which can be difficult to differentiate from ... more Mayaro virus (MAYV) causes an acute febrile illness which can be difficult to differentiate from dengue or chikungunya. MAYV RNA can be detected in plasma during the first 3-5days of illness, but only a single rRT-PCR has been fully evaluated in the literature. To develop an rRT-PCR for MAYV and evaluate assay performance using human plasma and urine samples spiked with different MAYV strains. A MAYV rRT-PCR targeting a region of the 5'UTR and nsp1 gene was designed from the alignment of all complete-genome MAYV sequences to be compatible with existing laboratory protocols. The assay was evaluated using human samples spiked with six MAYV strains, including strains from each of the three genotypes. The linear range of the MAYV rRT-PCR extended from 1.0 to 8.0 log10copies/μL, and the lower limit of 95% detection was 8.2copies/μL. No detection was observed when the MAYV rRT-PCR was tested with genomic RNA from related arboviruses. The assay demonstrated linear amplification of all ...

Journal of medicinal food, Jan 27, 2017

Alfalfa (Medicago sativa) has been extensively used as animal feed, due to its fiber, protein, mi... more Alfalfa (Medicago sativa) has been extensively used as animal feed, due to its fiber, protein, minerals, and vitamins, being also a useful source of phenolic compounds with potential therapeutic benefits. Nevertheless, its potential use as human ingredient is scarce. The aim of this work was to assess the nutritional composition, amino acid profile, and antioxidant capacity (AOC) of freeze-dried juice (FDJ) and fibrous residual material (RM), two new alfalfa-derived products (Adps) recently launched as ingredients for beverage preparations. Results demonstrated a high content of proteins (23-30 g/100 g FDJ and 13-17 g/100 g RM), crude fiber (29 g/100 g RM), and minerals (such as sodium, calcium, iron, and zinc). No significant difference was found in caloric content (4 kcal/g). Essential and nonessential amino acids were quantified in both Adps being leucine and lysine the most abundant. Total phenolic and total flavonoid contents (TPC and TFC, respectively) and their changes along ...

Experimental parasitology, Jan 24, 2017

Schistosomiasis is a chronic parasitic disease caused by trematodes of the genus Schistosoma, end... more Schistosomiasis is a chronic parasitic disease caused by trematodes of the genus Schistosoma, endemic in tropical and subtropical regions. The hepatic pathology of this parasitic disease could develop complications, such as fibrosis and cirrhosis, which can be fatal. The Venezuelan endemic area is considered as one of low transmission, which complicates the detection of infected individuals and signals the importance of improving the sensitivity of immunodiagnostic methods. Using ELISA, an evaluation was conducted of IgM and IgG responses to soluble antigens of eggs and female worms (SEA and SFWA) and excretion-secretion products of eggs and female worms (ESPE and ESPAW) in infected Balb/c mice with different parasitic burden and infection times. A high positivity rate by IgM detection was observed for all antigen preparations in 7-week infections (100% by SEA, SFWA, ESPE, and ESPWA in high parasitic burden) as well as a reduction of this immunoglobulin in chronic infection. Positiv...

Revista Med, Jun 1, 2009

O carcinoma de preliminar intrabony escamocelular a mandibular esta, no acordo com a classificaca... more O carcinoma de preliminar intrabony escamocelular a mandibular esta, no acordo com a classificacao da organizacao World-wide da saude, dentro dos carcinomas dos odontogenicos. Neoplasia e um pouco comum, com um homem da relacao: mulher de 3,5:1 e uma frequencia mais grande da apresentacao entre a quinta e sexta decada da vida. Sua posicao mais comum esta na regiao do posteroinferior a mandibular, sendo localmente aggressive, com o metastasis ao ganglia lymphatic regional. Porque seu comportamento e intrabony e aquele nao se apresentar/exposicao os ferimentos iniciais intraoral, seu diagnostico clinico e periodos longos dificeis, durando sem sua presenca e suspeitado. Confirmar seu diagnostico requer de um estudo do anatomopatologico que detecte a presenca de pilhas epithelial dos carcinomatosas intrabony. Imagenologicamente e demonstrado como um ferimento atypical do quistica, bad definido em a maioria dos casos, radiolucida e com o osteolisis no formulario do L. O tratamento da eleicao, com alvos dos curativos, e a realizacao de um exeresis com margens de seguranca amplas do oncologica e uma cirurgia mais atrasada do reconstructiva. O exemplo de um paciente de 31 anos de idade com um carcinoma aparece neste artigo de preliminar intrabony escamocelular do tipo continuo da maxila, a que um reseccion lhe foi feito a direita mandibular no bloco, seguido de cirurgias dos reconstructivas ate obter um resultado funcional e aesthetic apropriado. Palavras-chave: tumor odontogenico mandibular, carcinoma intra-osseio primario, PIOC, mandibula

PALAIOS, 2014

ABSTRACT Drillholes represent direct evidence of ecological interactions in the fossil record. Mo... more ABSTRACT Drillholes represent direct evidence of ecological interactions in the fossil record. Most of them have been interpreted as predatory in origin and enable the analysis of behavioral information of both predator and prey. Drillholes have been found in a variety of fossil organisms, but this is the first report of a bored fossil chiton plate. It was found in the La Coronilla deposit, a Late Pleistocene invertebrate assemblage from southeastern Uruguay. The drillhole belongs to the ichnospecies Oichnus simplex and is attributed to a muricid gastropod, which could likely have been the ocenebrinid Urosalpinx haneti, recorded in the fossil assemblage. The drillhole features all traits for a predatory origin. However, the rareness of this particular interaction between chitons and gastropods in the fossil record and in the recent, could signify an event of arbitrary drilling. The reported occurrence here raises the question as to whether this behavior represents an understudied ecological interaction between polyplacophorans and gastropods.