OALib Journal期刊

ISSN: 2333-9721




2018 ( 12 )

2017 ( 8 )

2016 ( 7 )

2015 ( 138 )


匹配条件: “Santiago;” ,找到相关结果约4663条。
Modeling Agricultural Change through Logistic Regression and Cellular Automata: A Case Study on Shifting Cultivation  [PDF]
Santiago Lopez
Journal of Geographic Information System (JGIS) , 2014, DOI: 10.4236/jgis.2014.63021

Agricultural expansion is one of the prime driving forces of global land cover change. Despite the increasing attention to the factors that cause it, the patterns and processes associated with indigenous cultivation systems are not well understood. This study analyzes agricultural change associated with subsistence-based indigenous production systems in the lower Pastaza River Basin in the Ecuadorian Amazon through a spatially explicit dynamic model. The model integrates multiple logistic regression and cellular automata to simulate agricultural expansion at a resolution consistent with small scale agriculture and deal with inherently spatial processes. Data on land use and cultivation practices were collected through remote sensing and field visits, and processed within a geographic information system framework. Results show that the probability of an area of becoming agriculture increases with population pressure, in the vicinity of existing cultivation plots, and proximity to the center of human settlements. The positive association between proximity to cultivation areas and the probability of the presence of agriculture clearly shows the spillover effect and spatial inertia carried by shifting cultivation practices. The model depicts an ideal shifting cultivation system, with a complete cropping-fallow-cropping cycle that shows how agricultural areas expand and contract across space and over time. The model produced relatively accurate spatial outputs, as shown by the results of a spatial comparison between the simulated landscapes and the actual one. The study helped understand local landscape dynamics associated with shifting cultivation systems and their implications for land management.

Is the Space-Time a Superconductor?  [PDF]
Wenceslao Santiago-Germán
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.410174

At the fundamental level, the 4-dimensional space-time of our direct experience might not be a continuum and discrete quantum entities might “collectively” rule its dynamics. Henceforth, it seems natural to think that in the “low-energy” regime some of its distinctive quantum attributes could, in principle, manifest themselves even at macroscopically large scales. Indeed, when confronted with Nature, classical gravitational dynamics of spinning astrophysical bodies is known to lead to paradoxes: to untangle them, dark matter or modifications to the classical law of gravity are openly considered. In this article, the hypothesis of a fluctuating space-time acquiring “at large distances” the properties of a Bose-Einstein condensate is pushed forward: firstly, it is shown that a natural outcome of this picture is the production of monopoles, dyons, and vortex lines of “quantized” gravitomagnetic—or gyrogravitational—flux along the transition phase; the minimal supported “charge” (and multiples of it) being directly linked with a nonzero (minimal) vacuum energy. Thus, a world of vibrating, spinning, interacting strings whose only elements in their construction are our topological concepts of space and time is envisioned, and they are proposed as tracers of the superfluid features of the space-time: the archetypal embodiment of these physical processes being set by the “gravitational roton”, an analogue of Landau’s classic higher-energy excitation used to explain the superfluid properties of helium II. The far and the near field asymptotics of string line solutions are presented and used to deduce their pair-interaction energy. Remarkably, it is found that two stationary, axis-aligned, quantum space-time vortices with the same sense of spin not only exhibit zones of repulsion but also of attraction, depending on their relative geodetic distance.

Enzyme Kinetic Equations of Irreversible and Reversible Reactions in Metabolism  [PDF]
Santiago Imperial, Josep J. Centelles
Journal of Biosciences and Medicines (JBM) , 2014, DOI: 10.4236/jbm.2014.24005

This paper compares the irreversible and reversible rate equations from several uni-uni kinetic mechanisms (Michaelis-Menten, Hill and Adair equations) and bi-bi mechanisms (single- and double- displacement equations). In reversible reactions, Haldane relationship is considered to be identical for all mechanisms considered and reversible equations can be also obtained from this rela- tionship. Some reversible reactions of the metabolism are also presented, with their equilibrium constant.

A Systematic Computational Study on Flavonoids
Santiago Aparicio
International Journal of Molecular Sciences , 2010, DOI: 10.3390/ijms11052017
Abstract: 17 selected flavones derivatives, flavonoids, were analyzed through a systematic B3LYP∕6-311++G** computational study with the aim of understanding the molecular factors that determine their structural and energetic properties in gas phase. Flavonoids were selected in a systematic way to infer the effect of the number and relative positions of hydroxyl groups on molecular properties. Different conformers for each flavonoid were analyzed and the strength and topology of the intramolecular hydrogen bonds studied through the computation of the corresponding torsional profiles. Atoms in a Molecule, and Natural Bond Orbital methodology was applied to the analysis of charge distribution along the studied molecules, and the intramolecular hydrogen bonds. Molecular shapes were studied through full geometry optimization, and the position of the catechol ring analyzed through dihedral scans.
Advances in hormone replacement therapy: making the menopause manageable
Santiago Palacios
BMC Women's Health , 2008, DOI: 10.1186/1472-6874-8-22
Abstract: The differences in age at initiation and the duration of HRT are key points. HRT appears to decrease coronary disease in younger women, near menopause; yet, in older women, HRT increases risk of a coronary event. Although HRT is a recognized method in the prevention and treatment of osteoporosis, it is not licensed for the prevention of osteoporosis as a first-line treatment. The effectiveness of low and ultra-low estrogen doses has been demonstrated for the treatment of vasomotor symptoms, genital atrophy and the prevention of bone loss, with fewer side-effects than the standard dose therapy. Further research, however, is needed to determine the effect both on fractures, as well as on cardiovascular and breast diseases. Newer progestins show effects that are remarkably different from those of other assays. The effectiveness of testosterone at improving both sexual desire and response in surgically and naturally postmenopausal women is shown by the testosterone patch.The intention, dose and regimen of HRT need to be individualized, based on the principle of choosing the lowest appropriate dose in relation to the severity of symptoms and the time and menopause age.By 2030, an estimated 47 million women will be undergoing menopause each year [1]. The loss of circulating estrogens that occurs during the menopausal transition manifests itself through a variety of symptoms (hot flushes, night sweats and vaginal atrophy). Approximately 75–80% of women experience menopausal symptoms, almost half of whom find the symptoms distressing, while 20–30% have severe symptoms [2,3].For decades, estrogen, either alone or in combination with progestins, has been the therapy of choice for the relief of menopausal symptoms, as well as for the longer-term prevention of postmenopausal osteoporosis [3]. The results of two large studies on HRT (The Heart and Estrogen/progestin Replacement (HERS) Study and the Women's Health Initiative (WHI) Study), [4,5] [table 1], however, have modified t
Díkaion Revista de Fundamentación Jurídica , 2010,
Abstract: the article contends that argentina's regulation of the elements of legal validity of an administrative act can be philosophically justified as a specification of the elements of aquinas' concept of "law". the article expounds the definition and elements of validity required by argentina's constitutional and administrative law. then, it analyzes each one of those elements from the standpoint of each of the philosophical elements of aquinas' concept of "law". the article concludes that each one of the administrative act's elements of validity finds an explanation in one or several of the elements of the philosophical concept of "law", demonstrating that this reasoning is an adequate way to explain those legal regulations.
Ideas y Valores , 2011,
Abstract: some scholars have pointed out the phenomenological character of the theory of natural selection, in the sense that it does not propose new theoretical terms. since others have held that one of the characteristics of explanatory theories is that they conceptually enrich their field of application, it could be said that the theory in question is lacking with respect to its explanatory capacity. the article addresses this issue by proposing an informal reconstruction of the darwinian theory of natural selection using structuralist meta-theoretical tools. the objective is to show that the theory suggests at least one explanatory concept, which could be called "aptitude", although all of its concepts are non-theoretical in the structuralist sense.
La magia en la saga de Hrólfr Kraki
Temas medievales , 2008,
Abstract: the article analyses magical elements present in the saga of king hrolfr kraki, a medieval icelandic saga classified within the group of the oldest sagas. attention is devoted to the words used in the different sections of the saga in calling the practitioners of magic and their techniques. on ground of this some elements of a possible social use of this vocabulary referring to magic in medieval iceland is sketched.
Os excessos da identidade: Bento XVI e a quest?o da tolerancia
Santiago, Homero;
Lua Nova: Revista de Cultura e Política , 2008, DOI: 10.1590/S0102-64452008000200008
Abstract: this article tries to comprehend the doctrinal base of some polemical assessments of benedict xvi; discussing its effects on the issue of religious tolerance. after presenting what is understood to mean tolerance, it proposes a way through the encyclical letter deus caritas est; in this letter, the new papal doctrine is founded on a particular interpretation of the notion of "god's love". lastly, it intends to show how this "love", by an exaggerated emphasis on the idea of identity, becomes an instrument of fight against every difference, spoiling the possibility of a pacific relationship among the religions and, consequently, sowing the seeds of fundamentalism.
Las pruebas rápidas en la promoción, prevención y diagnóstico de la sífilis
Infectio , 2008,
Abstract: a short review about the potential impact of rapid tests in the diagnosis, promotion and prevention of syphilis is presented. some clinical and laboratory aspects of postnatal and congenital syphilis are mentioned as well.

Copyright © 2008-2017 Open Access Library. All rights reserved.