Seasonal Responses of Phyloplankton Productivity to Water-Quality Variations in a Coastal Karst Ecosystem of the Yucatan Peninsula

Dzilam Lagoon (DL) is a shallow, semienclosed, coastal ecosystem located on the north coast of the Yucatan Peninsula. With 9.4 km3 surface area, this system is influenced by groundwater (GD) supply and inorganic nutrients drained from the nearby mangrove. DL is highly preserved and provides a unique site to address the seasonal responses of phytoplankton production to environmental variability in a karstic and pristine scenario. Twelve monthly sampling trips were undertaken during Sep. 1998–Aug. 1999 to record in situ physicochemical parameters and collect water for inorganic nutrients, chlorophyll a (Chl a), and phytoplankton production at seven stations plus one GD. Highest Chl a concentrations were determined at the innermost points of the lagoon, whereas primary production peaked at brackish zones. The average net primary production in DL (80 g C m-3 yr-1) is lower than that reported for other coastal lagoons of the Yucatan Peninsula. Differences in the physical setting and disturbance extent between DL and those ecosystems are discussed as the context underlying their distinct production levels

Complicaciones en las fracturas supracondíleas de húmero en la infancia.

La fracturas supracondíleas de húmero tienen gran incidencia en la infancia, y además pueden presentar una gran cantidad de complicaciones previas y posteriores al tratamiento. Se realiza una revisión de las complicaciones más frecuentes en las fracturas supracondíleas de húmero en los niños.Supracondylar fractures of the humerus present high incidence in children, moreover, a high per - centage of complications may be present, both previously as posteriorly to treatment. A review of the most com - mon complications in supracondylar humerus fractures in children is performed

Revisión y actualización del tratamiento de las fracturas supracondíleas de húmero en la infancia

La fractura supracondílea de húmero en la infancia es una patología con gran incidencia en los niños. Su tratamiento está rodeado de muchos puntos controvertidos. Se realiza una revisión histórica del tratamiento de esta patología y una actualización de las nuevas técnicas que han surgido a lo largo de los años.Supracondylar fracture of the humerus in childhood presents high incidence in children. The treat - ment of this fracture is surrounded by many controversial points. A historical review of the treatment of this injury and an update about emerging techniques during last years were done

1-methylcyclopropeneand storage temperature effect in postharvest of mandarin (Citrus reticulata L.) var. Arrayana

La producción de mandarina dentro del grupo de los cítricos tiene un aporte significativo en Colombia. El uso del 1-metilciclopropeno (1-MCP) inhibe la acción del etileno y es una práctica común para prolongar la vida poscosecha de productos perecederos. En frutos cítricos, especialmente en mandarina var. Arrayana, no se tiene caracterizado el efecto del 1-MCP en combinación con temperatura de almacenamiento. Por tanto, es importante establecer el efecto del 1-MCP y de la temperatura de almacenamiento sobre el comportamiento poscosecha del fruto de mandarina (Citrus reticulata L.) var. Arrayana cosechados en madurez comercial. Para este estudio se utilizó un diseño completamente al azar (DCA) con arreglo factorial 3 x 2: con temperaturas de almacenamiento de 6, 12 y 18°C (ambiente) como primer factor y la presencia o ausencia de 1-MCP (0,5 μL L-1 con 2 h de tratamiento) como segundo factor. Se midieron las variables sólidos solubles totales, tasa respiratoria, acidez total titulable, firmeza, clorofila total e índice de color cada 7 días durante 34 días de almacenamiento. A los 22 días de almacenamiento, independientemente de la aplicación de 1-MCP, el tratamiento a 12°C estimula cambios en la coloración de la epidermis, mayor degradación de clorofilas y mayor índice de color. A esta temperatura no se presenta daño por frío y no es importante la aplicación de 1-MCP. No obstante, a temperaturas menores (6°C) la conservación es mayor, el desverdizado es lento y se presenta menor índice de color, lo que conlleva a mayor tiempo de conservación. De acuerdo con los resultados, la temperatura de 12°C es adecuada para el desverdizado de mandarina var. Arrayana hasta los 22 días de almacenamiento, y 6°C es una temperatura alternativa para almacenamientos más prolongados, hasta de 34 días; manejos poscosecha no reportados anteriormente para esta variedad.Mandarin accounts for a significant part of citrus production in Colombia. The use of 1-methylcyclopropene (1-MCP) inhibits the action of ethylene and constitutes a common practice for extending the postharvest life of perishable products. In citrus fruits, especially tangerine var. Arrayana, the effect of 1-MCP in combination with storage temperature has not been characterized. It is therefore important to establish the effect of these two combined factors on the postharvest behavior of mandarin fruits (Citrus reticulata L.) var. Arrayana harvested at commercial maturity. A completely randomized design with a 3 x 2 factorial arrangement was employed for the study: the first factor corresponded to storage temperatures of 6, 12 and 18°C (room temperature), while the second factor was the presence or absence of 1-MCP (0,5 μL L-1 for two hours). The fruits were kept in storage room for a period of 34 days, during which total soluble solids, respiratory rate, total titratable acidity, firmness, total chlorophyll and color index were assessed every 7 days. After 22 days of storage, and regardless of the application of 1-MCP, 12°C treatment stimulate fruit skin discoloration and increased chlorophyll degradation and color index. At this temperature, no frost damage occurred and the application of 1-MCP was not important. However, at temperatures below 6°C, lower degreening and color index values were observed, thus leading to longer shelf life times. According to the results, 12°C is a suitable temperatur for the degreening of tangerine var. Arrayana until 22 days of storage; and 6°C is an alternative temperature for longer storage times, up to 34 days. No postharvest management had been previously reported for this variety.Fil: Gómez, Carlos A.. Universidad Nacional de ColombiaFil: Herrera, Aníbal O.. Universidad Nacional de ColombiaFil: Flórez, Víctor J.. Universidad Nacional de Colombi

Selective focusing of electrons and holes in a graphene-based superconducting lens

We show that a graphene pnp junction with a central superconducting electrode acts as a Veselago lens for incoming electrons by focusing them and their phase-conjugated counterpart (holes) into di erent points of the optical axis. This selective focusing suggested by a simple trajectory analysis is con rmed by fully microscopic calculations. Although the focusing pattern is degraded by deviations from the ideal conditions we show that it remains visible for a wide range of parameters. We discuss how this property can be useful for the detection of entangled electron pairs.This work was supported by COLCIENCIAS, project 110152128235 (S.G. and W.J.H.), and MICINN-Spain via Grant No. FIS2008-04209 and EU project SE2N

Bondian frames to couple matter with radiation

A study is presented for the non linear evolution of a self gravitating distribution of matter coupled to a massless scalar field. The characteristic formulation for numerical relativity is used to follow the evolution by a sequence of light cones open to the future. Bondian frames are used to endow physical meaning to the matter variables and to the massless scalar field. Asymptotic approaches to the origin and to infinity are achieved; at the boundary surface interior and exterior solutions are matched guaranteeing the Darmois--Lichnerowicz conditions. To show how the scheme works some numerical models are discussed. We exemplify evolving scalar waves on the following fixed backgrounds: A) an atmosphere between the boundary surface of an incompressible mixtured fluid and infinity; B) a polytropic distribution matched to a Schwarzschild exterior; C) a Schwarzschild- Schwarzschild spacetime. The conservation of energy, the Newman--Penrose constant preservation and other expected features are observed.Comment: 20 pages, 6 figures; to appear in General Relativity and Gravitatio

Antimicrobial resistance profiles of listeria monocytogenes and listeria innocua isolated from ready-to-eat products of animal origin in Spain

The objective of this work was to investigate the antimicrobial resistance in Listeria spp. isolated from food of animal origin. A total of 50 Listeria strains isolated from meat and dairy products, consisting of 7 Listeria monocytogenes and 43 Listeria innocua strains, were characterized for antimicrobial susceptibility against nine antimicrobials. The strains were screened by real-time PCR for the presence of antimicrobial resistance genes: Tet M, tet L, mef A, msr A, erm A, erm B, lnu A, and lnu B. Multidrug resistance was identified in 27 Listeria strains, 4 belonging to L. monocytogenes. Resistance to clindamycin was the most common resistance phenotype and was identified in 45 Listeria strains; the mechanisms of resistance are still unknown. A medium prevalence of resistance to tetracycline (15 and 9 resistant and intermediate strains) and ciprofloxacin (13 resistant strains) was also found. Tet M was detected in Listeria strains with reduced susceptibility to tetracycline, providing evidence that both L. innocua and L. monocytogenes displayed acquired resistance. The presence of antimicrobial resistance genes in L. innocua and L. monocytogenes indicates that these genes may be transferred to commensal and pathogenic bacteria via the food chain; besides this, antibiotic resistance in L. monocytogenes could compromise the effective treatment of listeriosis in humans

Topografía de la densidad mineral osea: Método de estudio "in vivo" de la cabeza femoral humana mediante TAC

Presentamos un método, no descrito anteriormente, que permite obtener un mapa muy preciso de la distribución topográfica de la densidad mineral ósea relativa de cualquier parte del esqueleto, en el sujeto vivo, a partir de una imagen TAC convencional. El método se basa en la medición directa de los niveles de gris de la imagen TAC, los cuales guardan una relación de linealidad con las Unidades Honsfield, de manera que la densidad óptica de un punto concreto se correlaciona con la densidad ósea del mismo. En nuestro estudio lo hemos aplicado a la cabeza femoral humana, obteniendo la imagen topográfica tridimensional de sus densidades óseas.We describe a new method to obtain an accurate mapping of the bone mineral density which can be applied to any area of the human skeleton in a live subject using conventional CT scan imaging. The method involves direct measurement of grey colour intensity from the CT image. The colour intensity maintains a direct relationship with the Honsfield Units, therefore the optic density of a given area is related to the bone density. In our study this method has been applied to the human femoral head to obtain a three-dimensional topography of the bone density

"Innovatio educativa tertio millennio": 12 years evoluting from learning from learning to teaching in courses on educational innovation and collaboration with the UNESCO chair of mining and industrial heritage

Twelve years ago a group of teachers began to work in educational innovation. In 2002 we received an award for educational innovation, undergoing several stages. Recently, we have decided to focus on being teachers of educational innovation. We create a web scheduled in Joomla offering various services, among which we emphasize teaching courses of educational innovation. The “Instituto de Ciencias de la Educacion” in “Universidad Politécnica de Madrid” has recently incorporated two of these courses, which has been highly praised. These courses will be reissued in new calls, and we are going to offer them to more Universities. We are in contact with several institutions, radio programs, the UNESCO Chair of Mining and Industrial Heritage, and we are working with them in the creation of heritage courses using methods that we have developed

Pulse quality analysis on soliton pulse compression and soliton self-frequency shift in a hollow-core photonic bandgap fiber

A numerical investigation of low-order soliton evolution in a proposed seven-cell hollow-core photonic bandgap fiber is reported. In the numerical simulation, we analyze the pulse quality evolution in soliton pulse compression and soliton self-frequency shift in three fiber structures with different cross-section sizes. In the simulation, we consider unchirped soliton pulses (of 400 fs) at the wavelength of 1060 nm. Our numerical results show that the seven-cell hollow-core photonic crystal fiber, with a cross-section size reduction of 2%, promotes the pulse quality on the soliton pulse compression and soliton self-frequency shift. For an input soliton pulse of order 3 (which corresponds to an energy of 1.69 μJ), the pulse gets compressed with a factor of up to 5.5 and a quality factor of 0.73, in a distance of 12 cm. It also experiences a soliton-self frequency shift of up to 28 nm, in a propagation length of 6 m, with a pulse shape quality of ≈ 0.80