Are estuaries traps for anthropogenic nutrients? Evidence from estuarine mesocosms

A series of estuarine mesocosms is described, where nutrient budgets were used to determine rates of nitrogen and phosphorus trapping and export as a function of nutrient input level, season, and presence or absence of sediments. Regardless of treatment or season these experimental systems exported most of the N and P that they received. Control systems with sediments retained none of the inflowing N and P during summer, and 5 % of N and 25 % of P inputs during winter. Eutrophied systems with sediments initially retained 30 % of added N and P due to increases in water column and sediment nutrient standing stocks in response to daily inorganic nutrient additions; however, after 6 mo of daily nutrient loading, these treatments retained only 5 to 15 % of nutrients added. Results of this study suggest that well-mixed estuarine systems may export to offshore waters most of the nitrogen and phosphorus that they receive. For the small percentage of nutrients that were retained, there was more storage during winter than summer, more storage in treatments without sediments, and more retention of P than N. Nitrogen losses through sediment denitrification accounted for 10 to 20 % of the N input to controls, and less than 10% of the N input to eutrophied treatments. The addition of nutrients to the eutrophied treatments resulted in increases in the N and P content of surface sediments, and the rapid deposition of an N and P-rich detrital layer on the bottom of the treatments without sediments

Benthic community metabolism in a coastal lagoon ecosystem

Measurements of benthic oxygen production and consumption at 3 stations over an annual cycle in a shallow (mean depth = 0.7 m) coastal lagoon on the Rhode Island (USA) coast provide evidence that shallow benthic communities may consume more organic matter than can be provided by impressive rates of in situ epifloral production. While sandy sediment areas in Potter Pond lagoon showed a net daytime production of about 140 g C m-2 yr-l, the more extensive areas of fine-grained sediment did not show any significant amount of net benthic daytime production annually. Moreover when nighttime respiratory costs were included, the lagoon benthos as a whole showed a net organic consumption of 30 g C m-2 yr-l in spite of a net annual daytime production rate of 50 g C m-2 yr-l. Rates of in situ oxygen uptake by fine-grained lagoon sediments in the dark were not separable from those of similar sediments in much deeper (mean = 8.6 m) Narragansett Bay. For the lagoon as a whole, the benthos consumed about 40 to 50% of the combined primary production by phytoplankton, macrophytes and benthic epiflora. This partitioning is similar to that found in deeper, plankton-based systems with completely heterotrophic bottom communities

Dynamical ultrafast all-optical switching of planar GaAs/AlAs photonic microcavities

The authors study the ultrafast switching-on and -off of planar GaAs/AlAs microcavities. Up to 0.8% refractive index changes are achieved by optically exciting free carriers at 1720 nm and a pulse energy of 1.8 micro Joules. The cavity resonance is dynamically tracked by measuring reflectivity versus time delay with tunable laser pulses, and is found to shift by as much as 3.3 linewidths within a few picoseconds. The switching-off occurs with a decay time of around 50 ps. The authors derive the dynamic behavior of the carrier density and of the complex refractive index. They propose that the inferred 10 GHz switching rate may be tenfold improved by optimized sample growth.Comment: 1.) Replaced figure 1 (linear reflectivity) with a more recent and improved measurement 2.) Included a Figure of Merit for switching and compared to other recent contributions 3.) Explained more precisely the effect of embedded Quantum Dots (namely no effect on measurement) 4.) Changed wording in a few place

A Case Report of Candida albicans Costochondritis after a Complicated Esophagectomy

This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially.We present an unusual case of Candida albicans costochondritis after a complicated Ivor Lewis esophagectomy. This case exhibits that pain, erythema, and swelling over the costal cartilages should alert the possibility of infective costochondritis, especially in a postoperative patient. If a fungal agent is identified, aggressive surgical debridement and early commencement of antifungal therapy are likely determinants for a satisfactory outcome