Juan Aguirre | Universidad Autonoma de Nayarit -Mexico- (original) (raw)

Papers by Juan Aguirre

Microtremor recordings have become a useful tool for microzonation studies in countries with low ... more Microtremor recordings have become a useful tool for microzonation studies in countries with low to moderate seismicity and also in countries where there are few seismographs or the recurrence time for an earthquake is quite long. Microtremor recordings can be made at almost any time and any place without needing to wait for an earthquake. The measurements can be made

American Journal of Plant Sciences, 2012

This study was designed to examine relationships between climate and vegetation of the Pacific ri... more This study was designed to examine relationships between climate and vegetation of the Pacific rim of North America, from the Mediterranean deserts of California to Alaska's boreal taiga. Relations were inferred from temperature and rainfall data recorded at 457 weather stations and by sampling the vegetation around these stations. Climate data were used to construct climatograms, calculate forty one variables and detect main latitudinal and longitudinal gradients. In order to identify the best functions able to relate our variables, polynomial and non-polynomial regressions were performed. The k-means algorithm was the clustering method used to validate the variables that could best support our bioclimatic classification. The variable that best fitted our classification was finally used to prepare a discriminatory key for bioclimates. Across this extensive area three macrobioclimates were identified, Mediterranean, Temperate and Boreal, within which we were able to distinguish nine bioclimates. Finally, we relate the different types of potential natural vegetation to each of these bioclimates and describe their floristic composition and physiognomy.

Biomedical optics express, 2014

The ex vivo and in vivo imaging, and quantitative characterization of the degradation of surgical... more The ex vivo and in vivo imaging, and quantitative characterization of the degradation of surgical sutures (∼500 μm diameter) up to ∼1cm depth is demonstrated using a custom dark-field photo-acoustic microscope (PAM). A practical algorithm is developed to accurately measure the suture diameter during the degradation process. The results from tissue simulating phantoms and mice are compared to ex vivo measurements with an optical microscope demonstrating that PAM has a great deal of potential to characterize the degradation process of surgical sutures. The implications of this work for industrial applications are discussed.

Peinado Lorca, M., Macías Rodríguez, M.Á., Aguirre Martínez, J.L. & Delgadillo Rodríguez, J. 2009... more Peinado Lorca, M., Macías Rodríguez, M.Á., Aguirre Martínez, J.L. & Delgadillo Rodríguez, J. 2009. Phytogeography of the Pacific Coast of North America. Anales Jard. Bot. Madrid 66(2): 151-194 (in Spanish).

ABSTRACT This work assesses the effect of different settings of the acquisition parameters (distr... more ABSTRACT This work assesses the effect of different settings of the acquisition parameters (distribution of mesh points, density of sources and detectors) of a parallel-plate non-contact fdoT, in order to achieve the best possible imaging performance, ie using the minimum number of singular values of W to maximize the information content in acquired measurements while minimizing the computational cost

La Tomografía Óptica Difusiva por Fluorescencia (FDOT) es una modalidad de tomografía óptica que ... more La Tomografía Óptica Difusiva por Fluorescencia (FDOT) es una modalidad de tomografía óptica que permite obtener, de manera no-invasiva, la distribución espacial 3D de la concentración de sondas moleculares fluorescentes en animales pequeños in-vivo. El problema directo de FDOT puede ser modelado mediante un sistema de ecuaciones, d=Wf, donde W es la matriz de pesos que asocia las medidas (d), a la distribución espacial desconocida de la concentración de fluoróforo (f). Para obtener una buena calidad de imagen, el número de elementos de la matriz de pesos suele ser elevado y el coste computacional de hallar la solución puede ser muy grande. En este trabajo se ha estudiado el efecto de la distribución de puntos de la malla, densidad de fuentes y detectores, a través del espectro de valores singulares de la matriz de pesos, con la finalidad de maximizar la información contenida en los datos adquiridos a la vez que minimizamos el coste computacional.

IEEE Transactions on Medical Imaging, 2015

Raster-scan optoacoustic mesoscopy (RSOM) comes with high potential for in vivo diagnostic imagin... more Raster-scan optoacoustic mesoscopy (RSOM) comes with high potential for in vivo diagnostic imaging in dermatology, since it allows for high resolution imaging of the natural chromophores melanin, and hemoglobin at depths of several millimeters. We have applied ultra-wideband RSOM, in the 10 MHz to 160 MHz frequency band, to image healthy human skin at distinct locations. We analyzed the anatomical information contained at different frequency ranges of the optoacoustic (photoacoustic) signals in relation to resolving features of different skin layers in vivo. We further compared results obtained from glabrous and hairy skin and identify that frequencies above 60 MHz are necessary for revealing the epidermal thickness, a prerequisite for determining the invasion depth of melanoma in future studies. By imaging a benign nevus we show that the applied RSOM system provides strong contrast of melanin-rich structures. We further identify the spectral bands responsible for imaging the fine structures in the stratum corneum, assessing dermal papillae, and resolving microvascular structures in the horizontal plexus.

Optics Letters, 2014

We have imaged for the first time to our knowledge human skin in vivo with a raster-scan optoacou... more We have imaged for the first time to our knowledge human skin in vivo with a raster-scan optoacoustic mesoscopy system based on a spherically focused transducer with a central frequency of 102.8 MHz and large bandwidth (relative bandwidth 105%). Using tissue phantoms we have studied the ability of the system to image vessels of sizes within the anatomically significant range from the key anatomical vasculature sites. The reconstructed images from experiments in vivo show several structures from the capillary loops at the dermal papillae, the horizontal plexus, and the difference between the dermis and the epidermis layers.

Astrophysics and Space Science Proceedings, 2010

We present our activities of popularization of Astronomy at Rey Juan Carlos University in Madrid,... more We present our activities of popularization of Astronomy at Rey Juan Carlos University in Madrid, especially our 30-hour workshop for people older than 55 (University for the Elderly) held since the academic year 2002/2003. Our course aims to introduce the basic topics on Astronomy to a group of motivated students who, in most cases, were not able to complete their education in their youth due to the historical environment of Spain in the middle of the 20th century.

Plant Ecology, 1997

This phytosociological study, carried out according to the Braun-Blanquet method and supported by... more This phytosociological study, carried out according to the Braun-Blanquet method and supported by cluster analysis, describes Walter's zonobiomes along the North American Pacific coast between the California-Oregon state border and Alaska (USA), including some interior zones of British Columbia and the Yukon Territory (Canada). Twenty two floristic associations are identified and each is characterized by a unique floristic combination, a distinctive geographical range and particular bioclimatic or edaphic conditions.

2009 Ieee Nuclear Science Symposium Conference Record, Vols 1-5, 2009

Monte Carlo methods provide a flexible and rigorous solution to the problem of light transport in... more Monte Carlo methods provide a flexible and rigorous solution to the problem of light transport in turbid media, which enable approaching complex geometries for a closed analytical solution is not feasible. The simulator implements local rules of propagation in the form of probability density functions that depend on the local optical properties of the tissue.

Biomedical Optics Express, 2011

Fluorescence diffuse optical tomography (fDOT) is an imaging modality that provides images of the... more Fluorescence diffuse optical tomography (fDOT) is an imaging modality that provides images of the fluorochrome distribution within the object of study. The image reconstruction problem is ill-posed and highly underdetermined and, therefore, regularisation techniques need to be used. In this paper we use a nonlinear anisotropic diffusion regularisation term that incorporates anatomical prior information. We introduce a split operator method that reduces the nonlinear inverse problem to two simpler problems, allowing fast and efficient solution of the fDOT problem. We tested our method using simulated, phantom and ex-vivo mouse data, and found that it provides reconstructions with better spatial localisation and size of fluorochrome inclusions than using the standard Tikhonov penalty term.

International journal of food microbiology, Jan 27, 2015

Quantitative microbial risk assessment requires the knowledge of the effect of food preservation ... more Quantitative microbial risk assessment requires the knowledge of the effect of food preservation technologies on the growth parameters of the survivors of the treatment. This is of special interest in the case of the new non-thermal technologies that are being investigated for minimal processing of foods. This is a study on the effect of pulsed light technology (PL) on the lag phase of Bacillus cereus spores surviving the treatment and the maximum growth rate (μmax) of the survivors after germination. The D value was estimated as 0.35J/cm(2) and our findings showed that PL affected the kinetic parameters of the microorganism. A log linear relationship was observed between the lag phase and the intensity of the treatment. Increasing the lethality lengthened the mean lag phase and proportionally increased its variability. A polynomial regression was fitted between the μmax of the survivors and the inactivation achieved. The μmax decreased as intensity increased. From these data, and t...

International journal of food microbiology, Jan 3, 2013

Listeria innocua micropopulation lag phase and its variability have been modeled as a function of... more Listeria innocua micropopulation lag phase and its variability have been modeled as a function of growth temperature, intensity of heat stress, and the number of surviving cells initiating growth. Micropopulation lag phases were found to correlate negatively with inoculum size and growth temperature and positively with heat shock intensity. Validation of the models using experimental milk samples indicated that the average lag phase duration predicted is shorter and more variable than the observed, meaning that they should be considered safe for risk assessment. Our results suggest that the effect of inoculum size on the population lag phase has both stochastic and physiological components.

International journal of food microbiology, Jan 3, 2011

The effect of electron beam irradiation on microbial inactivation and duration of lag time of ind... more The effect of electron beam irradiation on microbial inactivation and duration of lag time of individual surviving cells of Listeria innocua, Enterococcus faecalis, Pseudomonas fluorescens and Salmonella Enteritidis has been studied. In addition, the data on variability in microbial inactivation and duration of lag phase for surviving microbes have been fitted by normal and gamma distributions, respectively. The standard deviations of survivor number and lag phase duration of individual cells were higher in irradiated batches than in non-irradiated ones. Furthermore, the more intense the irradiation treatment was, the higher the variability in both survivor number and duration of lag phase of survivors. These findings should be considered in predictive models of microbial inactivation, in risk assessment, and in adjusting preserving and/or storage conditions in the food industry.