Formation of NH4[Hg-3(NH)(2)](NO3)(3) and transformation to [Hg2N](NO3)

NH4[Hg-3(NH)(2)](NO3)(3) (1) and [Hg2N](NO3) (2) are obtained from cone. aqueous ammonia solutions of Hg(NO3)(2) at ambient temperature and under hydrothermal conditions at 180 degreesC, respectively, as colourless and dark yellow to light brown single crystals. The crystal structures {NH4[Hg-3(NH)(2)](NO3)(3): cubic, P4(I)32, a = 1030.4(2) pm, Z = 4, R-all = 0.028; [Hg2N](NO3): tetragonal, P4(3)2(1)2, a = 1540.4(1), c = 909.8(1) pm, Z = 4, R-all = 0.054} have been determined from single crystal data. Both exhibit network type structures in which [HNHg3] and [NHg4] tetrahedra of the partial structures of 1 and 2 are connected via three and four vertices, respectively. 1 transforms at about 270 degreesC in a straightforward reaction to 2 whereby the decomposition products of NH4NO3 are set free. 2 decomposes at about 380 degreesC forming yellow HgO. Most certainly, I is identical with a mineral previously analyzed as

Direct and indirect effects of species displacements; an invading freshwater amphipod can disrupt leaf litter processing and shredder efficiency

Invasive species may threaten the fundamental role played by native macroinvertebrate shredders in determining energy flow and the trophic dynamics of freshwater ecosystems. Functionally, amphipods have long been regarded as mainly shredders, but they are increasingly recognized as major predators of other macroinvertebrate taxa. Furthermore, intraguild predation (IGP) between native and invasive amphipods underlies many species displacements. We used laboratory mesocosms to investigate what might happen to shredders and leaf-litter processing in water bodies invaded by the highly predatory Ponto-Caspian amphipod Dikerogammarus villosus, which is spreading rapidly throughout Europe and may soon invade the North American Great Lakes. The leaf-shredding efficiency of D. villosus was significantly lower than that of 3 Gammarus species (2 native and 1 invasive) that D. villosus has either already displaced or may be currently displacing in The Netherlands. In addition, D. villosus was a major predator of all of these native and invasive amphipod shredders and of a common isopod shredder Asellus aquaticus. Leaf processing in Gammarus and Asellus mesocosms declined rapidly in the presence of D. villosus and ceased altogether within 4 d because by then, all potential shredders had been killed and consumed. Furthermore, the shredding efficiency of surviving amphipods and isopods declined significantly within 2 d of the release of D. villosus, a result indicating that predator-avoidance behavior may override leaf processing. We discuss the implications of these direct and indirect effects of D. villosus invasions and species displacements on community structure and litter processing in aquatic ecosystems. © 2011 The North American Benthological Society.


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Resting energy expenditure in non-ventilated, non-sedated patients recovering from serious traumatic brain injury: Comparison of prediction equations with indirect calorimetry values

Background & aims: Little is known about energy requirements in brain injured (TBI) patients, despite evidence suggesting adequate nutritional support can improve clinical outcomes. The study aim was to compare predicted energy requirements with measured resting energy expenditure (REE) values, in patients recovering from TBI.

Methods: Indirect calorimetry (IC) was used to measure REE in 45 patients with TBI. Predicted energy requirements were determined using FAO/WHO/UNU and Harris–Benedict (HB) equations. Bland– Altman and regression analysis were used for analysis.

Results: One-hundred and sixty-seven successful measurements were recorded in patients with TBI. At an individual level, both equations predicted REE poorly. The mean of the differences of standardised areas of measured REE and FAO/WHO/UNU was near zero (9 kcal) but the variation in both directions was substantial (range 591 to þ573 kcal). Similarly, the differences of areas of measured REE and HB demonstrated a mean of 1.9 kcal and range 568 to þ571 kcal. Glasgow coma score, patient status, weight and body temperature were signi?cant predictors of measured REE (p < 0.001; R²⁼ 0.47).

Conclusions: Clinical equations are poor predictors of measured REE in patients with TBI. The variability in REE is substantial. Clinicians should be aware of the limitations of prediction equations when estimating energy requirements in TBI patients.

Amplitude and Phase Controlled Reflectarray Element Based on an Impedance Transformation Unit

An architecture to simultaneously affect both amplitude and phase control from a reflectarray element using an impedance transformation unit is demonstrated. It is shown that a wide range of control is possible from a single element, removing the conventional necessity for variable sized elements across an array in order to form a desired reflectarray far-field pattern. Parallel plate waveguide measurements for a 2.2 GHz prototype element validate the phase and amplitude variation available from the element. It is demonstrated that there is sufficient control of the element's reflection response to allow Dolph-Tschebyscheff weighting coefficients for major-lobe to side-lobe ratios of up to 36 dB to be implemented.

Culture and the Irish Border:Spaces for Conflict Transformation

The Irish border has been described as a ‘natural’ cultural divide between the island's two dominant indigenous ethno-national communities. However, an examination of key resources of ethno-national group culture - religion, sport and language - provides evidence to challenge this representation. Moreover, in the post-1994 period of conflict transformation, evidence is also presented to support the proposition that the Irish border region has developed into a cultural space in which Irish nationalist and Ulster unionist ethno-national communities can explore cultural differences and commonalities through cross-border, cross-community contact and communication in small group encounters. This space underpins the reconfiguration of the border from barrier to political bridge between North and South. European Union (EU) Peace programmes for Ireland, beginning in 1995, provided the support for a cross-border approach to escaping the cage of ethno-national conflict in Northern Ireland. However, post-2004 EU enlargement signalled the beginning of the end for EU Peace funding and severe economic recession has undermined the expectation of British-Irish intergovernmental intervention to support cross-border partnerships and their work. Therefore, the outlook for the sustainability of this cross-border cultural space is gloomy with potentially deleterious consequences for the continued reconfiguration of the border from barrier to bridge.

Confronting the Settler Legacy: Indigenisation and Transformation in South Africa and Zimbabwe

This article examines attempts to negotiate a perceived residual dominance of settler populations in South Africa and Zimbabwe by means of developmental and cultural policies deemed necessary to restore sovereignty to Africans. Indigenisation has become a preferred strategy for reconstructing post-colonial states in Africa: indigenisation of the economy as part of a Third Chimurenga in Zimbabwe and Black Economic Empowerment in the socio-cultural context of Ubuntu in South Africa. These are issues arising from the regional legacy of contested and uneven transitions to majority rule. Identifying how governments frame the ‘settler problem’, and politicise space in doing so, is crucial for understanding post-colonial politics. Indigenisation in Zimbabwe allows the government to maintain a network of patronage and official rhetoric is highly divisive and exclusivist although couched in terms of reclaiming African values and sovereignty. Revival of Ubuntu as a cultural value system in South Africa facilitates a more positive approach to indigenisation, although Black Economic Empowerment displays elitist tendencies and cultural transformation remains controversial and elusive. The perceived need to anchor policy in socially acceptable (i.e., ostensibly indigenous/traditional) contexts has become a prominent feature of post-colonial politics and is indicative of an indigenous turn in Southern African politics.

Stranding events provide indirect insights into the seasonality and persistence of jellyfish medusae (Cnidaria : Scyphozoa)

It is becoming increasingly evident that jellyfish (Cnidaria: Scyphozoa) play an important role within marine ecosystems, yet our knowledge of their seasonality and reproductive strategies is far from complete. Here, we explore a number of life history hypotheses for three common, yet poorly understood scyphozoan jellyfish (Rhizostoma octopus; Chrysaora hysoscella; Cyanea capillata) found throughout the Irish and Celtic Seas. Specifically, we tested whether (1) the bell diameter/wet weight of stranded medusae increased over time in a manner that suggested a single synchronised reproductive cohort; or (2) whether the range of sizes/weights remained broad throughout the stranding period suggesting the protracted release of ephyrae over many months. Stranding data were collected at five sites between 2003 and 2006 (n = 431 surveys; n = 2401 jellyfish). The relationship between bell diameter and wet weight was determined for each species (using fresh specimens collected at sea) so that estimates of wet weight could also be made for stranded individuals. For each species, the broad size and weight ranges of stranded jellyfish implied that the release of ephyrae may be protracted (albeit to different extents) in each species, with individuals of all sizes present in the water column during the summer months. For R. octopus, there was a general increase in both mean bell diameter and wet weight from January through to June which was driven by an increase in the variance and overall range of both variables during the summer. Lastly, we provide further evidence that rhizostome jellyfish may over-wintering as pelagic medusa which we hypothesise may enable them to capitalise on prey available earlier in the year.