T. Córdova-fraga - Academia.edu (original) (raw)

Papers by T. Córdova-fraga

Physical Review Materials

Strain engineering is a powerful mean for tuning the various functionalities of ABO3 perovskite o... more Strain engineering is a powerful mean for tuning the various functionalities of ABO3 perovskite oxide thin films. Rare-earth orthoferrite RFeO3 materials such as NdFeO3 (NFO) are of prime interest because of their intriguing magnetic properties as well as their technological potential applications especially as thin films. Here, using a large set of complementary and advanced techniques, we show that NFO epitaxial thin films, successfully grown by pulsed laser deposition on (001)-SrTiO3, show a strong magnetic anisotropy below a critical thickness tc of ~54 nm, associated to the occurrence of structural modifications related to symmetry and domain pattern changes. By varying the tensile misfit strain through the decrease of film thickness below tc, the amplitudes of in-and out-of-plane magnetization can be continuously tuned while their ratio keeps constant. Furthermore, different low temperature magnetic behaviours are evidenced for strained and relaxed films suggesting that the strain-induced structural state impacts the magnetic phase stability.

AIP Conference Proceedings, 2004

The human stomach is a J shaped hollowed organ that undergoes a variable luminal volume without s... more The human stomach is a J shaped hollowed organ that undergoes a variable luminal volume without significant pressure changes. This organ has two valves: the cardiac localized in the upper part, and the pillory on the lower part of the organ respectively. The main functions of these valves are to storage, carry, triturate and empty the lumen content. However, their

Advances in Bioscience and Biotechnology, 2014

Sound transmission has been used for diagnosis of hip dysplasia in newborns and infants with tunn... more Sound transmission has been used for diagnosis of hip dysplasia in newborns and infants with tunning fork and sthetoscope. The study aims to identify the validity of a device based on sound transmission. Male and female newborns from Celaya, Gto, ranging from 4 to 28-day-old were selected for the study. The sound transmission device was used both, in bilateral assessment (compared sound transmission) and on each hip separately (sound transmission with extension/flexion). In the first application if the sound is lower by a digit, there is a hip unhealthy. In the second application if the sound is increased by a digit, there is also an alteration of the hip. A hip ultrasound was applied using the Graf technique as a gold standard. Sensitivity, specificity and predictive values were calculated to identify validity. The intra-observer and inter-observer Kappa Test was applied to identify reliability. The hips of 103 newborns were assessed, obtaining a sensitivity of 60.9%, and a specificity of 92%; it should be a positive predictive value of 51.9% and a negative predictive value of 95% for the compared sound transmission test. In the sound transmission test with extension/flexion, the values were 82.6%, 96.2%, 73.1% and 97.8% for sensitivity, specificity, positive predictive value and negative predictive value, respectively. The result of the intra-observer kappa was 0.80 and the inter-observer was 0.70 for the compared sound transmission. The intra-observer Kappa was 0.88 and the inter-observer was 0.78 for the compared sound transmission test with extension/flexion. The device for sound transmission is valid and reliable for the diagnosis of dysplastic development hip disease in newborns. N. Padilla-Raygoza et al.

International Congress Series, 2007

An alternative to assess arterial pulse wave (APW) is proposed. The blood pressure changes measur... more An alternative to assess arterial pulse wave (APW) is proposed. The blood pressure changes measurement at the jugular anatomical region, using a differential magnetic gradiometer was performed through sensing the slight mechanical pulsations of the skin without applied manual pressure. A well defined waveform, resembling general features of the electrocardiogram QRS complex, is obtained. The potential application of a non-expensive clinical monitoring of the APW measured at the jugular region and at other point of interest could be the precise pulse time differences to performed arterial pulse wave velocity (APWV) measurements.

Bioinspiration & Biomimetics, 2013

Ager C: see Filipiak W 027107 Ager C: see Filipiak W 036008 Amann A: see Filipiak W 027107 Amann ... more Ager C: see Filipiak W 027107 Ager C: see Filipiak W 036008 Amann A: see Filipiak W 027107 Amann A: see Filipiak W 036008 Amann A: see Fuchs D 027101 Amann A: see King J 016005 Amor-Carro O: see Nunez-Naveira L 046003 Aoyama I, Yaegaki K, Calenic B, Ii H, Ishkitiev N and Imai T: The role of p53 in an apoptotic process caused by an oral malodorous compound in periodontal tissues: a review 017104 Aoyama I: see Ishkitiev N 017103 Apfel CC: see Hornuss C 046004

AIP Conference Proceedings, 2008

Esophagus transit time measurement is a common clinical practical. Biomagnetic techniques and mod... more Esophagus transit time measurement is a common clinical practical. Biomagnetic techniques and modern instrumentation can perform non invasive and functional assessments of the gastrointestinal tract. This study presents the evaluation of the esophagus transit time and propulsion velocity of a magnetic marker from the mouth to stomach using water vs. a swallow easy substance recently patented. A group of ten

Journal of Electronic Materials

Journal of Intelligent & Fuzzy Systems, 2019

It is increasingly common for internet users to have access to blogs and social networks, and com... more It is increasingly common for internet users to have access to blogs and social networks, and common for them to express opinions on such sites. This research work is framed within the scope of opinion mining. Opinions allow us to measure people's perception of a specific topic or product. Knowing the opinion that a person has towards a product or service is of great help for decision making, since it allows, between other things, that potential consumers to verify the quality of the product or service before using it. This research work is framed within the scope of opinion mining. When the number of opinions is very large the analysis gets more complicated and generally resort to tools that allow this task to be performed automatically are sought out. The present work performs an automatic categorization of textual opinions corresponding to four products: books, DVDs, kitchens, and electronics. Both negative and positive opinions are considered for the experiment. Further categorization experiments are performed using different domains of learning. The basic idea is to investigate if we can undertake classification of opinions, positive and negative, of any given domain using instances of training from a different domain. Results obtained from different methods of learning are presented. The results obtained allow us to examine the feasibility of the proposed methodology.

AIP Conference Proceedings, 2000

In this work we propose for the particular problem of penetration of substance into skin, a setup... more In this work we propose for the particular problem of penetration of substance into skin, a setup which is based on the conventional photoacoustic cell. In order to avoid some problems, intrinsic to the material under study and the sensibility of the technique, we use the thermal effusivity of the skin-substance system to monitor this phenomenon, in vivo and in situ. We measure the changes of thermal effusivity due to the absorption of some topical medicaments. These values are compared with those from an adjacent sample of clean skin (without medicament, natural fats or transpiration). This experiment was performed on a volunteer in different parts of the human skin. We use stainless steel (250 mm thickness) as the thermally thin light absorbance surface. The values for this parameter are in agreement with some reported in the literature. Besides the measurements described above. .

International Journal of Computer and Electrical Engineering, 2016

The physical parameter for the so-called Biologically Active Points most documented in the litera... more The physical parameter for the so-called Biologically Active Points most documented in the literature is the electrical impedance. These points seem to have higher electrical conductance than their surrounding points. The stimulation of these points is made not only mechanically and electrically but also optically (laser acupuncture) and thermically (moxibustion). We evaluated by optoacoustic technique and by photothermal radiometry, some skin points along the PC acupuncture meridian in the forearm region. We found a slight relative increment in absorption in some regions around the meridian region but without a definite association with an acupoint. Moreover, the same case can be applied to a non-meridian line. In radiometric signals we did not find differences with respect to control points in a two layer model. Based in these results we can not conclude that such points are optically or thermally special.

Clinical EEG and Neuroscience, 2013

AIP Conference Proceedings, 2011

A magnetic system has been built in order to study electrical activity of human stomach. This set... more A magnetic system has been built in order to study electrical activity of human stomach. This setup is based in the Helmholtz coils configuration, which generates magnetic fields of order of mT. This field will be used to stimulated magnetic tracer enclosed into the stomach, where it adds a remnant magnetic field of nT.

Physiological Measurement, 2004

A magnetic pulse generator has been set up in order to study gastric activity. Two coils 1.05 m i... more A magnetic pulse generator has been set up in order to study gastric activity. Two coils 1.05 m in diameter, arranged in a Helmholtz configuration, were used. The system generated magnetic field pulses higher than 15 mT, of duration 17.3 ± 1.2 ms. Measurements were performed in 11 male volunteers, with average age 29.3 ± 6.4 years and body mass index 26.0 ± 4.8 kg m −2. Magnetite (Fe 3 O 4) particles with diameters from 75 to 125 µm were used as magnetic tracers, which were mixed in 250 ml of yogurt in concentrations from 2 to 5 g. Signals were registered by using a high speed 3 axis fluxgate digital magnetometer and processed to determine the relaxation of the magnetic tracers by fitting a first-order exponential function to the data, a mean relaxation constant κ = 116 ± 40 s −1 was obtained. Also, an average gastric peristaltic frequency was measured; a value of 3.2 ± 0.3 cpm was determined.

E. Hernandez Torres, A. L. MacKay, E. MacMillan, T. Cordova Fraga, A. Ramirez Manzanares, A. Curt... more E. Hernandez Torres, A. L. MacKay, E. MacMillan, T. Cordova Fraga, A. Ramirez Manzanares, A. Curt, D. Li, B. Mädler, and M. Dvorak Division de Ciencias e Ingenierias, Universidad de Guanajuato, Leon, Guanajuato, Mexico, Radiology, University of British Columbia, Canada, Vancouver, Brithish Columbia, Canada, Physics & Astronomy, University of British Columbia, Canada, Vancouver, Brithish Columbia, Canada, Clinical Research, University of Bern, Facultad de Matematicas, Universidad de Guanajuato, Guanajuato, Guanajuato, Mexico, Spinal Cord Injury Center, University of Zurich, Philips Healthcare, Vancouver, Brithish Columbia, International Collaboration on Repair Discoveries