Elysia timida (Risso, 1818) three decades of research

Elysia timida (Risso, 1818) three decades of research.— During the last 30 years, studies on Elysia timida (Risso, 1818) have addressed various aspects related to food sources, photosynthetic efficiency of kleptoplasts, population genetics, chemical ecology and reproductive biology, both in the Mediterranean Sea and in the Mar Menor coastal lagoon. E. timida shows a strong specific interaction with Acetabularia acetabulum, retaining functional chloroplasts for at least 45 days and obtaining extra energy in periods when food resources are scarce. It shows control of parapodia, avoiding pigment photodestruction under oversaturated light conditions. The chemical ecological relationships established between E. timida and its potential predator fish, Thalassoma pavo, have also been evaluated, and it has been found that that the extracts of the mollusc contain repellent and unpalatable polypropionate compounds. Population genetics has demonstrated the genetic divergence between populations showing high and significant values of FST and genetic distances, and at least six privative alleles that are not shared with Mediterranean populations have been detected in lagoon populations. This sacoglossan is a poecilogonic species, and its lagoon populations show a greater reproductive output than Mediterranean populations; they produce a greater number of egg masses and embyros per individual, and the capsules have a wider diameter

Granitos postcinemáticos de tendencia alcalina en Ossa Morena: el stock de la Cardenchosa (prov. de Córdoba)

El stock de La Cardenchosa forma part d'un grup de granits post-cinemàtics de tendència alcalina d'edat posttournaisiana i que afloren en la zona d'Ossa Morena. Aquests granits presenten com trets característics l'allargament N-S dels seus afloraments, el seu emplaçament superficial, la presència de fàcies leucocràtiques i l'íntima connexió dels jaciments de fluorita i/o barita. La composició química i menirelògica del stock de La Cardenchosa és comparada amb altres de la mateixa regió

Magnitude of formative flows in stream potholes

Although it is generally recognized that geomorphic work is tied to bedrock channel reshaping, the importance of low vs. high flow stages that cause the most geomorphic impact remains unclear. The objective of the research is to study the concept of “formative flow” in bedrock channels and determine, through morphological studies, if those flows have any impact on sculpted features such as potholes and how this relationship relates to various inputs such as flow stages (magnitude and frequency), shear stress, and sediment size. Here, we studied the distribution of the main pothole typologies and tried to understand why potholes are found along bedrock river channels. Specifically, we examined stream potholes from three locations along the Spanish Central System: Alberche, Tietar, and Manzanares rivers. We conducted the research by taking precise geometric measurements, classifying potholes, analyzing flow magnitude and frequency, and using a two-dimensional (2D) hydrodynamic model to assess key variables in Manzanares river. This research demonstrated that bankfull depths completely cover all pothole typologies in all the analyzed sites but are not sufficient to achieve its formative flow depth (FFD). Using a detailed 2D hydrodynamic model in Manzanares river, we discovered that dimensions of cylindrical potholes are closely related to bankfull discharge and that this depth is connected to FFD. Other potholes, such as erosive-compound and erosive-lateral, are historical remnants, and their shapes are not related to any particular FFD and are likely associated with rare events and catastrophic breaks. A collection of laterals that exhibit FFD near bankfull flows appear to represent a part of the recent evolution of a knickpoint. To summarize, it can be inferred from the findings that the utility of morphological analysis in conjunction with the 2D hydrodynamic model is to examine the fraction of erosional/active features to determine the degree of senescence and/or change in natural conditions in a river reach.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUERegional Government of Madrid (Spain)pu

Estimation of the Efficiency of Hydraulic Pumps

A sustainable design of water supply systems needs to account operational costs. When pumping is required, the energy consumed by the pumps plays a major part in the operational costs, and the efficiency of the pumps can greatly affect the energy expenses. How to properly estimate the value of pump efficiency is hence of great importance. The aim of this study is to study in depth the efficiency of hydraulic pumps, in relation with the other design variables (flow rate, pumping head, power, etc.). For that, 400 hydraulic pumps were analysed. A strong relationship between the flow rate and the pump efficiency was observed. This relationship was interpolated, and three empiric curves were defined (one for the average maximum and minimum expected value of pump efficiency). These curves can be easily used by designers in order to obtain an estimation of the efficiency of the hydraulic pumps

Pegmatitas en materiales metamórficos del norte de la provincia de Córdoba. Mineralogía y posibilidades económicas

[Resumen] En relación con rocas metamórficas de edad Precámbrica y metamorfismo de grado medio-alto se han estudiado más de 60 masas de pegmatitas cuarzo-feldespáticas compuestas por cuarzo, feldespato potásico, albita, moscovita, turma1 ina, granate, biotita, menas metálicas, minerales de uranio y otros. Las masas pegmatíticas son de formas irregulares o 1entejonares subconcordantes con la esquistosidad regional más manifiesta. Sus dimensiones oscilan entre unos decímetros y decenas de metros, y su continuidad lateral su pera en algunos casos los trescientos metros. Considerando sólo las masas de potencia métrica, por sus reservas, cal idad química de sus principales especies minerales, tamaño de grano, texturas, etc. es planteable la obtención industrial de cuarzo, feldespato potásico, feldespato sódico y moscovita[Abstract] More than 60 outcrops of quartz-fe1despatic pagmatites have been studied re1ated with Precambrian metamorphic rocks of medium-high grade. The pagmatites are composed of quartz, potash fe1dspar, a1bite, muscovite, turma1 ine, garnet, biotite, ores, uranium minerals and others. The pegmatite outcrops hare irregular o lenticular forms, subparallell to the main regional schistosity. They vary in size between a few decimeters to some tens of meters, whi1e su lateral continuity exceed in sorne cases 300 meterse By taking into account on1y the outcrop of metric size, their stocks, chemica1 qual ity of the main mineral species, grain size, texture, etc., it can be planned the industrial recovery of quartz, potash feldspar, sodic fe1dspar and muscovit

Materiales silico-carbonosos en el Precámbrico de Sierra Morena

[Resumen] Se aborda, por primera vez, un estudio comparativo de las cuarcitas negras del Precámbrico de Sierra Morena, evidenciando su carácter de rocas sílico-carbonosas, asociadas a sucesiones con importantes aportes volcánicos y producidas por precipitaci6n química-bioquímica de sílice en medios marinos someros y restringidos. Se discute su distribuci6n, valor en la correlación es tratigráfica, evoluci6n textural con el aumento del metamorfismo y la deformación y algunos de los caracteres generales de su quimismo y mineralogíaAbstract] A comparative study of the black quarzites of the Precambrian of Sierra ~orena is atte~pted here for the 'first time, which reveals their character of silicacarbonaceous rocks related to succesion with important volcanic contributions and produced by chemical-biochemical precipitacion of silica in restricted and shallow marine environments. It is discussed their distribution value in .stratigraphical correlation, textural evolution with increasing rnetamorfism ando deformation, and sorne of the general character of its chemistry and mineralog