Nitrogen uptake and internal recycling in Zostera marina exposed to oyster farming: eelgrass potential as a natural biofilter

Oyster farming in estuaries and coastal lagoons frequently overlaps with the distribution of seagrass meadows, yet there are few studies on how this aquaculture practice affects seagrass physiology. We compared in situ nitrogen uptake and the productivity of Zostera marina shoots growing near off-bottom longlines and at a site not affected by oyster farming in San Quintin Bay, a coastal lagoon in Baja California, Mexico. We used benthic chambers to measure leaf NH4 (+) uptake capacities by pulse labeling with (NH4)-N-15 (+) and plant photosynthesis and respiration. The internal N-15 resorption/recycling was measured in shoots 2 weeks after incubations. The natural isotopic composition of eelgrass tissues and vegetative descriptors were also examined. Plants growing at the oyster farming site showed a higher leaf NH4 (+) uptake rate (33.1 mmol NH4 (+) m(-2) day(-1)) relative to those not exposed to oyster cultures (25.6 mmol NH4 (+) m(-2) day(-1)). We calculated that an eelgrass meadow of 15-16 ha (which represents only about 3-4 % of the subtidal eelgrass meadow cover in the western arm of the lagoon) can potentially incorporate the total amount of NH4 (+) excreted by oysters (similar to 5.2 x 10(6) mmol NH4 (+) day(-1)). This highlights the potential of eelgrass to act as a natural biofilter for the NH4 (+) produced by oyster farming. Shoots exposed to oysters were more efficient in re-utilizing the internal N-15 into the growth of new leaf tissues or to translocate it to belowground tissues. Photosynthetic rates were greater in shoots exposed to oysters, which is consistent with higher NH4 (+) uptake and less negative delta C-13 values. Vegetative production (shoot size, leaf growth) was also higher in these shoots. Aboveground/belowground biomass ratio was lower in eelgrass beds not directly influenced by oyster farms, likely related to the higher investment in belowground biomass to incorporate sedimentary nutrients

Transitional Justice: Key Concepts, Processes and Challenges

This briefing paper focuses on transitional justice as one of the key steps in peacebuilding that needs to be taken to secure a stable democratic future. It provides key stakeholders with an overview of transitional justice and its different components, while examining key challenges faced by those working in this area. The paper focuses on key concepts of transitional justice before addressing its traditional components: justice, reparation, truth and institutional reform. The paper concludes with some remarks that challenge the traditional concept of transitional justice and its processes in order to initiate important debate on where future work in this field is needed

Spectral gaps of simplicial complexes without large missing faces

Let $X$ be a simplicial complex on $n$ vertices without missing faces of dimension larger than $d$. Let $L_{j}$ denote the $j$-Laplacian acting on real $j$-cochains of $X$ and let $\mu_{j}(X)$ denote its minimal eigenvalue. We study the connection between the spectral gaps $\mu_{k}(X)$ for $k\geq d$ and $\mu_{d-1}(X)$. In particular, we establish the following vanishing result: If $\mu_{d-1}(X)>(1-\binom{k+1}{d}^{-1})n$, then $\tilde{H}^{j}(X;\mathbb{R})=0$ for all $d-1\leq j \leq k$. As an application we prove a fractional extension of a Hall-type theorem of Holmsen, Mart\'inez-Sandoval and Montejano for general position sets in matroids

Comment on the Article “Relativistic Non-Equilibrium Thermodynamics Revisited”

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.There are two problematic items in García-Colín and Sandoval-Villalbazo's approach to “relativistic non-equilibrium thermodynamics” (L.S. García- Colín and A. Sandoval-Villalbazo, J. Non-Equilib. Thermodyn. 31, 2006, pp. 11–22). The paper does not follow the fundamentals of relativity theory; according to them, the energy-momentum tensor (EMT) has to include all energies of the considered system. Secondly, strange thermodynamic consequences result by using the presuppositions made by the authors. The paper is critically discussed and some shortcomings are elucidated

Live-in domestic workers : overworked, underpaid and overlooked

Live-in domestics are the housekeepers, nannies and home health care workers that live with the families they work for five to seven nights a week. Like other domestics, the live-in domestics interviewed for this report suffered restriction of movement, isolation, inadequate nutrition, physical violence, wage theft and excessive overtime, all in Texas. Moreover, live-ins are more reluctant than other domestics to exercise their rights because they may automatically find themselves homeless. Nobody knows exactly how many live-in domestic workers are in the U.S. because of the secluded nature of their work, but experts and advocates agree that many live-in domestic workers are victims of human trafficking. There are more than 300,000 victims of human trafficking in Texas, nearly 234,000 of those were adult victims of labor trafficking, according to reports. The same reports found that traffickers exploit approximately $600 million per year from victims of labor trafficking in Texas only. Since 2012, domestic work has represented the largest sector of all labor trafficking cases reported to the National Human Trafficking Hotline. Texas is the second state with the most cases of human trafficking reported to the Hotline, second only to California. Like other states, these reported cases are growing every year. Reports also show that 85 percent of domestic worker trafficking survivors said having pay withheld or being paid well below minimum wage; 81 percent have lived in abusive living conditions; and 80 percent have been tricked with false or otherwise deceptive contracts. Through the lives of four present and former live-in domestic workers, these numbers come to life and live-in domestic workers stay in the shadows no more.Journalis

Estereotipos de género en universitarios españoles sobre el riesgo psicosocial en la infancia

Recent studies have shown that gender stereotypes are not sensitive to social changes. There is a gap in how gender is treated in college. This study is part of an innovation project to improve teaching quality in university. We aim to analyze the presence of gender stereotypes related to at-risk childhood in a sample of 113 university students. Most students considered that some circumstances, like substance consumption, are more likely in boys. On the contrary, they think that looking after siblings or anxiety are more common in girls. Results show the need to incorporate the gender perspective into universities. The special needs of the at-risk girls require further research and specialized training.Estudios recientes han mostrado que los estereotipos de género no son sensibles a los cambios sociales. Hay un vacío sobre cómo el género es tratado en la educación universitaria. Este estudio se enmarca en un proyecto de innovación para la mejora de la calidad docente en la universidad. Pretendemos analizar la presencia de estereotipos de género relacionados con menores en riesgo en una muestra de 113 universitarios. La mayoría de los estudiantes considera que algunas circunstancias, como el uso de sustancias, son más probables en chicos. Por el contrario, piensan que el tener que cuidar de los hermanos o la ansiedad son más comunes en chicas. Los resultados muestran la necesidad de incorporar la perspectiva de género en las universidades. Las necesidades de las chicas en riesgo requieren más investigación y formación especializada