Phytoplankton composition derived from CHEMTAX along 10°E during POLARSTERN cruise ANT-XXVIII/3, Jan-March 2012

Phytoplankton community structure and their physiological response in the vicinity of the Antarctic Polar Front (APF; 44°S to 53°S, centred at 10°E) were investigated as part of the ANT-XXVIII/3 Eddy-Pump cruise conducted in austral summer 2012. Our results show that under iron-limited (< 0.3 µmol/m**3) conditions, high total chlorophyll-a (TChl-a) concentrations (> 0.6 mg/m**3) can be observed at stations with deep mixed layer (> 60 m) across the APF. In contrast, light was excessive at stations with shallower mixed layer and phytoplankton were producing higher amounts of photoprotective pigments, diadinoxanthin (DD) and diatoxanthin (DT), at the expense of TChl-a, resulting in higher ratios of (DD+DT)/ TChl-a. North of the APF, significantly lower silicic acid (Si(OH)4) concentrations (< 2 mmol/m**3) lead to the domination of nanophytoplankton consisting mostly of haptophytes, which produced higher ratios of (DD+DT)/TChl-a under relatively low irradiance conditions. The Si(OH)4 replete (> 5 mmol/m**3) region south of the APF, on the contrary, was dominated by microphytoplankton (diatoms and dinoflagellates) with lower ratios of (DD+DT)/TChl-a, despite having been exposed to higher levels of irradiance. The significant correlation between nanophytoplankton and (DD+DT)/TChl-a indicates that differences in taxon-specific response to light are also influencing TChl-a concentration in the APF during summer. Our results reveal that provided mixing is deep and Si(OH)4 is replete, TChl-a concentrations higher than 0.6 mg/m**3 are achievable in the iron-limited APF waters during summer.

Sin nombre: drama en 3 actos y en verso

105 p.

Compendio de telecomunicaciones 3. Conceptos básicos de ingeniería de Radiopropagación

Este libro, desarrolla de manera directa y sencilla el fenómeno de la propagación de las señales electromagnéticas en las bandas de frecuencia de microondas. Aborda la teoría y criterios técnicos y prácticos concernientes al diseño de los radioenlaces puntos a punto (P-P), tanto análogos como digitales. Se incluyen anexos técnicos donde los estudiantes dispondrán de información especializada generada por los fabricantes internacionales de sistemas de Radio y Mux, así como los accesorios de protección y estructuras metálicos propias de estos sistemas (torres para antenas, sistemas de tierra, pararrayos, luces de obstrucción, etc.). Se confía que este libro sea de gran utilidad en la formación de los estudiantes de esta ingeniería.

A new low temperature synthesis route of fraipontite (Zn,Al)3(Si,Al)2O5(OH)4

A low temperature synthesis method based on the decomposition of urea at 90°C in water has been developed to synthesise fraipontite. This material is characterised by a basal reflection 001 at 7.44 Å. The trioctahedral nature of the fraipontite is shown by the presence of a 06l band around 1.54 Å, while a minor band around 1.51 Å indicates some cation ordering between Zn and Al resulting in Al-rich areas with a more dioctahedral nature. TEM and IR indicate that no separate kaolinite phase is present. An increase in the Al content however, did result in the formation of some SiO2 in the form of quartz. Minor impurities of carbonate salts were observed during the synthesis caused by to the formation of CO32- during the decomposition of urea.