428 research outputs found
Simple procedural method for estimating on-site soil erosion
CER76-77DBS-RML-TJW38.Prepared for USDA Forest Service, Rocky Mountain Forest and Range Experiment Station.Includes bibliographical references (pages 37-38).February 1977
Mapping of potential landslide areas in terms of slope stability
CER78-79DBS-RML-TJW19.Contract no. 16-712.O1-CA.Prepared for USDA Forest Service, Rocky Mountain Forest and Range Experiment Station.Includes bibliographical references (pages 57-62).November 1978
Glomus intraradices dominates arbuscular mycorrhizal communities in a heavy textured agricultural soil
Arbuscular mycorrhizal fungal (AMF) spore communities were surveyed in a long-term field fertilization experiment in Switzerland, where different amounts of phosphorus (P) were applied to soil. Plots receiving no P as well as plots systematically fertilized in excess to plant needs for 31 years were used to test the hypothesis that application of P fertilizer changes the composition and diversity of AMF communities. AMF spores were isolated from the field soil, identified, and counted so as to quantify the effect of P fertilization on AMF spore density, composition, and diversity. Trap cultures were established from field soil with four host plants (sunflower, leek, maize, and Crotalaria grahamiana), and the spore communities were then analyzed in substrate samples from the pots. Altogether, nine AMF species were detected in the soil. No evidence has been acquired for effect of P fertilization on spore density, composition, and diversity of AMF in both the field soil and in trap cultures. On the other hand, we observed strong effect of crop plant species on spore densities in the soil, the values being lowest under rapeseed and highest under Phacelia tanacetifolia covercrop. The identity of plant species in trap pots also significantly affected composition and diversity of associated AMF communities, probably due to preferential establishment of symbiosis between certain plant and AMF species. AMF spore communities under mycorrhizal host plants (wheat and Phacelia in the fields and four host plant species in trap pots) were dominated by a single AMF species, Glomus intraradices. This resulted in exceptionally low AMF spore diversity that seems to be linked to high clay content of the soi
Kaehler submanifolds with parallel pluri-mean curvature
We investigate the local geometry of a class of K\"ahler submanifolds which generalize surfaces of constant mean curvature. The role of
the mean curvature vector is played by the -part (i.e. the -components) of the second fundamental form , which we call the
pluri-mean curvature. We show that these K\"ahler submanifolds are
characterized by the existence of an associated family of isometric
submanifolds with rotated second fundamental form. Of particular interest is
the isotropic case where this associated family is trivial. We also investigate
the properties of the corresponding Gauss map which is pluriharmonic.Comment: Plain TeX, 21 page
Night vision and other stories
These stories are mysteries. They deal with the mystery of human existence. High seriousness and slapstick are the paradoxical elements of this existence. The region in which these elements blur marks the sphere of the stories
Dressing preserving the fundamental group
In this note we consider the relationship between the dressing action and the
holonomy representation in the context of constant mean curvature surfaces. We
characterize dressing elements that preserve the topology of a surface and
discuss dressing by simple factors as a means of adding bubbles to a class of
non finite type cylinders.Comment: 36 pages, 1 figur
A detailed study of cholinium chloride and levulinic acid deep eutectic solvent system for CO2 capture via experimental and molecular simulation approaches
Choline chloride + levulinic acid deep eutectic solvent is studied as a suitable material for CO2 capturing
purposes. The most relevant physicochemical properties of this solvent are reported together with the
CO2 solubility as a function of temperature. The corrosivity of this solvent is studied showing better
performance than amine-based solvents. A theoretical study using both density functional theory and
molecular dynamics approaches is carried out to analyze the properties of this fluid from the
nanoscopic viewpoint, and their relationship with the macroscopic behavior of the system and its ability
for CO2 capturing. The behavior of the liquid–gas interface is also studied and its role on the CO2
absorption mechanism is analyzed. The reported combined experimental and theoretical approach leads
to a complete picture of the behavior of this new sorbent with regard to CO2, which together with its
low cost, and the suitable environmental and toxicological properties of this solvent, lead to a promising
candidate for CO2 capturing technological applicationsMinisterio de Economı´a y Competitividad (Spain, project
CTQ2013-40476-R) and Junta de Castilla y Leo´n (Spain, project
BU324U1
MacDowell-Mansouri gravity and Cartan geometry
The geometric content of the MacDowell-Mansouri formulation of general
relativity is best understood in terms of Cartan geometry. In particular,
Cartan geometry gives clear geometric meaning to the MacDowell-Mansouri trick
of combining the Levi-Civita connection and coframe field, or soldering form,
into a single physical field. The Cartan perspective allows us to view physical
spacetime as tangentially approximated by an arbitrary homogeneous "model
spacetime", including not only the flat Minkowski model, as is implicitly used
in standard general relativity, but also de Sitter, anti de Sitter, or other
models. A "Cartan connection" gives a prescription for parallel transport from
one "tangent model spacetime" to another, along any path, giving a natural
interpretation of the MacDowell-Mansouri connection as "rolling" the model
spacetime along physical spacetime. I explain Cartan geometry, and "Cartan
gauge theory", in which the gauge field is replaced by a Cartan connection. In
particular, I discuss MacDowell-Mansouri gravity, as well as its more recent
reformulation in terms of BF theory, in the context of Cartan geometry.Comment: 34 pages, 5 figures. v2: many clarifications, typos correcte
La acetabuloplastia de Staheli en el tratamiento de la enfermedad de Legg-Calvé-Perthes en mayores de 6 años. Estudio preliminar
Objetivo: Valorar los resultados funcionales y radiográficos de la acetabuloplastia de Staheli como
alternativa terapéutica en el tratamiento quirúrgico de la enfermedad de Legg-Calvé-Perthes de debut tardÃo.Material
y método: Estudio retrospectivo de 7 pacientes con enfermedad de Legg-Calvé-Perthes tratados mediante
acetabuloplastia de Staheli con un tiempo de seguimiento medio de tres años y tres meses. Se analizan parámetros
clÃnicos (movilidad prequirúrgica y al final del seguimiento) asà como parámetros radiográficos (clasificación
de Herring, Ãndice acetábulo-cabeza de Heyman-Herndon y el ángulo centro-borde de Wiberg) previos al tratamiento
quirúrgico, tras el tratamiento quirúrgico y al final del seguimiento. Resultados: Tras el análisis estadÃstico
de los Ãndices radiográficos (Ãndice acetábulo-cabeza de Heyman-Herndon asà como ángulo de Wiberg) se
objetivaron diferencias estadÃsticamente significativas entre la radiografÃa prequirúrgica y postquirúrgica, pero
no se objetivaron diferencias estadÃsticamente significativas entre la postquirúrgica y la realizada al final del
seguimiento. Por lo tanto, los Ãndices radiográficos mostraron una mejora en sus parámetros que además se mantuvo
estable en el tiempo. Ningún paciente presentó complicaciones debidas a la cirugÃa. La exploración fÃsica
mostró una mejorÃa media de 10º en la rotación interna de la cadera. Conclusiones: La técnica de acetabuloplastia
según Staheli es una opción quirúrgica que conduce a la mejora de los resultados radiográficos y funcionales con
pocas complicaciones debidas al procedimiento.Objective: To evaluate the functional and radiographic results of Staheli's acetabuloplasty as therapeutic
option in the surgical treatment of Legg-Calvé-Perthes's disease of late debut. Material and method:
we did a retrospective study of seven patients with Legg-Calvé-Perthes's disease treated by means of Staheli's
acetabuloplasty with an average follow-up of three years and three months. We analyzed clinical parameters
(preoperative and "end of the follow-up" mobility) as well as radiographic parameters (Herring's classification,
Heyman-Herndon's index and Wiberg's center-edge angle) before the surgical treatment, after the surgical treatment
and at the end of the follow-up. Results: Any patients presented complications due to the surgery. The physical
exploration showed an average improvement of 10º in the internal rotation of the hip. After the statistical
analysis of the radiographic indexes (Heyman-Herndon's index as well as Wiberg's angle), there were statistically
significant differences between the preoperative X-ray and the postoperative one, but there were no statistically
significant differences between the postoperative one and the X-ray done at the end of the follow-up. Therefore,
the radiographic indexes showed an improvement in these parameters that in addition kept stable in time. Conclusions:
The technic of acetabuloplasty according to Staheli is a surgical option that leads to a good radiographic
and functional result with few complications due to the procedure
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