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Search Results: 1 - 10 of 77691 matches for " Juan Carlos Herguera "
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Subsidence of the Laguna Salada Basin, northeastern Baja California, Mexico, inferred from Milankovitch climatic changes
Juan Contreras,Arturo Martín-Barajas,Juan Carlos Herguera
Geofísica internacional , 2005,
Abstract: Laguna Salada in northern Baja California, Mexico, is an active half-graben product of the trans-tensional tectonics of the Gulf of California. It is sensitive to changes in sediment supply from the Colorado River basin. We present a time series analysis of the upper 980 m of a gamma-ray log from a borehole drilled near the Laguna Salada fault. The power spectrum of the gamma-ray log resembles the spectrum of δ18O Pleistocene isotopic variations from ice cores and from the deep ocean, known to be strongly controlled by Milankovitch cycles. We correlate δ18O stages with silty and sandy intervals in the log. Downcore ages for the last 780 ky are constrained within ~10 kyr. We derive a simple time vs. depth calibration relation for the basin over this time interval. Estimated sedimentation rates at the drill site appear to be constant with a value of ~1.6 mm/yr. We propose that this subsidence rate is produced by the Laguna Salada fault.
Decadal surface ocean variability in the lower Gulf of California: Records for the past 300 years
Juan Carlos Herguera,Gladys Bernal Franco,Adolfo Molina-Cruz
Geofísica internacional , 2003,
Abstract: Recent observational and theoretical studies of the Gulf of California have produced some new ideas and models about its circulation patterns and the controls on interannual to decadal timescales, that call on the importance of the tropical and equatorial Pacific as the main region of forcing. The available instrumental record for this region is of short duration, reaching back only into the early 1980s, which coupled with the poor resolution for previous years limits the validation of these models on longer timescales. To overcome the shortness of this record we resort to a reconstruction of SST variability for the last two centuries with the aid of the oxygen stable isotopic composition of calcitic shells preserved in the high-resolution laminated sediments that accumulate on the sea-floor of the La Paz basin, off the Baja California Peninsula eastern margin. From the analysis of the instrumental record we found that winter sea surface temperatures (SSTs) show greater variability from year to year than summer SSTs. Longer records further show a change in cold season temperatures with a trend towards warmer values at the turn of the last century, while the warm season SSTs show no corresponding trend, which underlines the sensitivity of cooler months to interannual SST variability in this region. We further present an extended SST record for the past three centuries based on a reconstruction from the stable oxygen isotopic composition of the planktic foraminifer Globigerina bulloides (d’Orbigny), shown to have its maximum production in the lower Gulf of California during the winter-spring season. This paleothermometer shows mean winter SSTs similar to the instrumentally recorded ones for the last 170 years while for the period between 1700 to 1830 shows cooler winters alternating with relatively warmer ones. The variability in winter SSTs on interannual to decadal timescales seem to be modulated by low-frequency ENSO variability, possibly through higher frequency and intensity of El Ni o/La Ni a events that temporarily lock surface ocean temperatures into warm/cold decadal periods, thus tracking tropical oceanographic variability on decadal timescales for the past two centuries through ocean driven feedbacks.
An Approach to the Understanding of Pictorial Space: A Methodological Proposal Based on Three Case Studies  [PDF]
Juan Carlos Meana
Creative Education (CE) , 2016, DOI: 10.4236/ce.2016.714191
Abstract: Space and time coordinates are two key parameters in our construction as cultural and social beings. They provide us with reference points in the creation of artistic images with full symbolic significance. With the aim of reflecting on pictorial space, an exercise was designed for second year undergraduate students at the Faculty of Fine Arts in the University of Vigo (Spain). This exercise, conducted under the subject Space-Time Processes, consisted in the student’s election of a single pictorial artwork from the history of art in order to subsequently carry out a pictorial intervention involving a dialogue with the space portrayed in the original artwork. From a qualitative methodological approach, an analysis of three cases was undertaken. This proposal promotes a type of active learning that lets the students take centre stage on the teaching-learning process, where they confront image comprehension as a group of visual and constructive codes loaded with meaning.
A Wave Function for the Spin of the Early Universe Derived from the Wheeler-DeWitt Equation  [PDF]
Juan Carlos Echaurren
International Journal of Astronomy and Astrophysics (IJAA) , 2017, DOI: 10.4236/ijaa.2017.72006
Abstract: The wave function for the spin the early universe is obtained through the adaption of the quantum formalism to one solution of the Wheeler-DeWitt’s equation [1], associated with the wave function of the universe. In addition, some observations performed by Stephen Hawking in relation to the vorticity of the universe [2] are used. This wave function for the spin could be used for indirectly to demonstrate the presence of dark matter in the universe.
Analysing Economic and Financial Power of Different Countries at the End of the Twentieth Century  [PDF]
Juan Carlos Molero, Francesc Pujol
Modern Economy (ME) , 2012, DOI: 10.4236/me.2012.32028
Abstract: This paper offers further evidence to “The Economist” index of economic power developed by Pujol (2002, 2003, and 2009). The original index is composite by construction and it gives information about year 2000, comparing the results with year 1990. Testing the robustness of the ranking of selected countries obtained by Pujol’s index; this paper applies the same methodology to two specific years: 1995 and 2001. The research tries to ascertain if the evolution of the rank- ing of countries among years 1990 and 2000 is not merely a chance. The number of times each country appears in tables and graphs of the different “The Economist” issues for year 1995 confirms the evolution of the index between 1990 and 2000. Data for year 2001 gives continuity and support to the ranking developed in year 2000. The data analyzed from this magazine make sense, because at the end it gives the same information that the one obtained from other more tradi- tional and sophisticated ways. Empirical results tend to confirm that unconventional composite index can produce relevant data sets for scientists and practitioners.
Hipoecogenic Nodule. Ultrasonographic findings of best positive prediction in the diagnosis of prostate carcinoma
Juan Carlos Mantilla Suarez,Juan Carlos Moncada
MedUNAB , 1999,
Hipotiroidismo neonatal: fisiopatogenia, aspectos moleculares, metabólicos y clínicos
Solis, Juan Carlos;Valverde, Carlos;
Revista de investigación clínica , 2006,
Abstract: this review provides an updated summary on both the clinical and diagnostic aspects of neonatal hypothyroidism (neh); as well as on the molecular and pathophysiologic processes known to be involved in the installment of this important hormonal deficiency. current information regarding its etiology and pathogenesis has allowed classigying neh in three major groups: endemic, transient, and sporadic hypothyroidism. the later corresponds to congenital hypothyroidism and encompasses a broad spectrum of hereditary disorders causing hypothyroidism in newborns and young children. these congenital disorders include hypothalamic-pituitary or thyroid dysgenesis and/or dyshormonogenesis, as well as hyporesponsiveness or resistance to either trh, tsh or to thyroid hormones. the introduction of national screening programs for neh have overcome the difficulties in the early diagnosis thus helping to prevent its serious and irreversible consequences on intellectual and physical development. concomitantly, an increase in the need for complementary etiologic and molecular diagnosis has risen. the current capability to perform a fine and precise diagnose is crucial both for treatment of the affected infant and for genetic counseling of the family. although incomplete, available epidemiological information in mexico indicates that neh prevalence can be as high as twice that in other developed world countries. on these bases, national public health policies and epidemiological surveyance must be strengthen not only to identify, diagnose and timely treat, but to prevent and eradicate endemic neh.
Proyecto de incubadora para prematuros de muy bajo peso de nacimiento
Juan Carlos Buscaglia,Carlos Carduzo
Revista del Hospital Materno Infantil Ramón Sardá , 2000,
Reforma del sistema de seguridad social y adquisición de formación
Juan Carlos Conesa,Carlos Garriga
Investigaciones Económicas , 2000,
Development of Bioartificial Myocardium Using Stem Cells and Nanobiotechnology Templates
Juan Carlos Chachques
Cardiology Research and Practice , 2011, DOI: 10.4061/2011/806795
Abstract: Cell-based regenerative therapy is undergoing experimental and clinical trials in cardiology, in order to limit the consequences of decreased contractile function and compliance of damaged ventricles following myocardial infarction. Over 1000 patients have been treated worldwide with cell-based procedures for myocardial regeneration. Cellular cardiomyoplasty seems to reduce the size and fibrosis of infarct scars, limit adverse postischemic remodelling, and improve diastolic function. The development of a bioartificial myocardium is a new challenge; in this approach, tissue-engineered procedures are associated with cell therapy. Organ decellularization for bioscaffolds fabrication is a new investigated concept. Nanomaterials are emerging as the main candidates to ensure the achievement of a proper instructive cellular niche with good drug release/administration properties. Investigating the electrophysiological properties of bioartificial myocardium is the challenging objective of future research, associating a multielectrode network to provide electrical stimulation could improve the coupling of grafted cells and scaffolds with host cardiomyocytes. In summary, until now stem cell transplantation has not achieved clear hemodynamic benefits for myocardial diseases. Supported by relevant scientific background, the development of myocardial tissue engineering may constitute a new avenue and hope for the treatment of myocardial diseases.
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