bluuebunny/crossref_metadata_2025 huggingface dataset:
Anomalous enrichment of O17 and C13 in photodissociation products of CO2: Possible role of nuclear spin
Authors: Mahata Sasadhar , Bhattacharya S. K.
Published: June 2009

Oxygen and carbon isotope fractionation associated with products (CO and O2) of gas phase photodissociation of CO2 have been studied using photons from Hg lamp (184.9 nm) and Kr lamp (123.6 and 116.5 nm). In dissociation by Hg lamp photons both CO and O2 are enriched in O17 by about 81‰ compared to the estimate based on a kinetic model. Additionally, CO is enriched in C13 by about 37‰ relative to the model composition. In contrast, in dissociation by higher energy Kr lamp photons no such anomaly was found in O2. The observed isotopic enrichments in case of Hg lamp dissociation are proposed to be due to a hyperfine interaction between nuclear spin and electron spins or orbital motion causing enhanced dissociation of isotopologues of CO2 containing O17 and C13. The O17 enrichment is higher than that of C13 by a factor of 2.2±0.2 which can be explained by the known magnetic moment ratio of O17 and C13 due to differing nuclear spins and g-factors. These results have potential implications in studies of the planetary atmospheres.
Dynamic optically induced planar terahertz quasioptics
Authors: Cooke D. G. , Jepsen P. Uhd
Published: June 2009

Optical control of the propagation direction of a terahertz pulse inside an optically transparent parallel plate waveguide is demonstrated by patterned charge carrier photoexcitation of a silicon slab embedded within the waveguide. It is shown experimentally and through finite element simulations that photoexcitations with sufficient conductivity can induce a partial reflection, capable of steering the pulse inside the two-dimensional waveguide. A beamsplitter is demonstrated as proof of principle and is used to delay the arrival of the reflected terahertz pulse at the detector by several picoseconds by moving the excitation in the plane.
Modeling the coalescence of sessile droplets
Authors: Sellier M. , Trelluyer E.
Published: June 2009

This paper proposes a simple scenario to describe the coalescence of sessile droplets. This scenario predicts a power-law growth of the bridge between the droplets. The exponent of this power law depends on the driving mechanism for the spreading of each droplet. To validate this simple idea, the coalescence is simulated numerically and a basic experiment is performed. The fluid dynamics problem is formulated in the lubrication approximation framework and the governing equations are solved in the commercial finite element software COMSOL. Although a direct comparison of the numerical results with experiment is difficult because of the sensitivity of the coalescence to the initial and operating conditions, the key features of the event are qualitatively captured by the simulation and the characteristic time scale of the dynamics recovered. The experiment consists of inducing coalescence by pumping a droplet through a substrate which grows and ultimately coalesces with another droplet resting on the substrate. The coalescence was recorded using high-speed imaging and also confirmed the power-law growth of the neck.
Direct correlation function of the square-well fluid with attractive well width up to two particle diameters
Authors: Hlushak S. , Trokhymchuk A. , Sokołowski S.
Published: June 2009

Analytical expression for direct correlation function of the square-well fluid with an attractive well width up to two particle diameters (2<λ≤3) is reported. This result is obtained within the first-order mean-spherical approximation (FMSA) and represents the nontrivial extension of the recent study due to Tang [J. Chem. Phys. 127, 164504 (2007)], where the width of square-well attraction was limited by one particle diameter (1<λ≤2). Prediction of the FMSA theory is validated by direct comparison against Monte Carlo simulation data. Additionally, an impact of the increase in the range of attraction on the parameters of the critical point of the square-well fluid is discussed using the compressibility route to thermodynamics.
Multiple coherent states for first-principles semiclassical initial value representation molecular dynamics
Authors: Ceotto Michele , Atahan Sule , Tantardini Gian Franco , Aspuru-Guzik Alán
Published: June 2009

A multiple coherent states implementation of the semiclassical approximation is introduced and employed to obtain the power spectra with a few classical trajectories. The method is integrated with the time-averaging semiclassical initial value representation to successfully reproduce anharmonicity and Fermi resonance splittings at a level of accuracy comparable to semiclassical simulations of thousands of trajectories. The method is tested on two different model systems with analytical potentials and implemented in conjunction with the first-principles molecular dynamics scheme to obtain the power spectrum for the carbon dioxide molecule.
Mean energy of some interacting bosonic systems derived by virtue of the generalized Hellmann–Feynman theorem
Authors: Fan Hong-yi , Xu Xue-xiang
Published: June 2009

By virtue of the generalized Hellmann–Feynman theorem [H. Y. Fan and B. Z. Chen, Phys. Lett. A 203, 95 (1995)], we derive the mean energy of some interacting bosonic systems for some Hamiltonian models without proceeding with diagonalizing the Hamiltonians. Our work extends the field of applications of the Hellmann–Feynman theorem and may enrich the theory of quantum statistics.
Increasing diffraction efficiency by heating phase gratings formed by femtosecond laser irradiation in poly(methyl methacrylate)
Authors: Hirono Satoshi , Kasuya Makoto , Matsuda Katsumi , Ozeki Yasuyuki , Itoh Kazuyoshi , Mochizuki Hiroyuki , Watanabe Wataru
Published: June 2009

The diffraction efficiency of phase gratings formed by femtosecond laser irradiation in poly(methyl methacrylate) was increased by more than an order of magnitude by subsequent heating below the glass transition temperature (Tg). The first-order Bragg diffraction efficiency of a 10 μm period grating was 1.9% without heating, whereas it increased to 72% when heated at 70 °C for 500 h. This is because the induced refractive index changes (Δn) were increased by heating. From the Lorentz–Lorenz equation, one of the reasons why Δn increases by heating could be a slight volume contraction in the irradiated area.
Setup for optimized grazing incidence x-ray absorption experiments on thin films on substrates
Authors: Maurizio C. , Rovezzi M. , Bardelli F. , Pais H. G. , D’Acapito F.
Published: June 2009

We present a state-of-the-art experimental apparatus and a proper setup to perform x-ray absorption spectroscopy (XAS) experiments in grazing incidence mode. This geometry is appropriate for doped thin films or interfaces buried at moderate depth in a thick matrix, whenever the scattering and/or fluorescence from the matrix has to be strongly attenuated. Both the calculation and the experimental data demonstrate that the specific setup that consists in a grazing incidence and grazing collection geometry is extremely advantageous. In fact, with respect to the standard geometry used to perform XAS experiments in fluorescence mode, the present setup allows an enhancement in the interesting fluorescence signal from the surface layer without a corresponding increase in the elastic scattering contribution from the matrix. The sample holder especially designed for this kind of experiment can work in vacuum and at low temperature. An easy and quick automatic sample alignment procedure is detailed.
Net motion of an ensemble of many Brownian particles captured with a self-mixing laser
Authors: Otsuka Kenju , Ohtomo Takayuki , Makino Hironori , Sudo Seiichi , Ko Jing-Yuan
Published: June 2009

The overall dynamics of Brownian particles suspended in water were captured with high time resolution by using a self-mixing thin-slice solid-state laser. The net motion of an ensemble of many particles moving in the small imaging field observed at given time intervals was found to be represented by Brownian motions of an effective medium obeying the Ornstein–Uhlenbeck process, whose physical parameters have scaling relations with those of a real turbid medium. An approach toward measuring particle diffusion constants is described.
Surface and interface phonon polaritons of wurtzite GaN thin film grown on 6H-SiC substrate
Authors: Ng S. S. , Yoon T. L. , Hassan Z. , Abu Hassan H.
Published: June 2009

Surface and interface phonon polaritons of wurtzite GaN thin film grown on 6H-SiC substrate are investigated experimentally and theoretically. Two strong absorption peaks that correspond to the surface and interface phonon polaritons are clearly observed at 710 and 916 cm−1, respectively. This observation is in good agreement with the results simulated using an anisotropy model. Finally, the obtained surface phonon polariton (SPP) mode is compared with the reported result. It is revealed that the SPP mode in the wurtzite GaN thin film is shifted toward higher frequency as compared to that in the wurtzite bulk GaN.
Experimental tests of effective mass and atomistic approaches to quantum dot electronic structure: Ordering of electronic states
Authors: Sewall Samuel L. , Cooney Ryan R. , Kambhampati Patanjali
Published: June 2009

The overall symmetry of the envelope functions for the four lowest energy excitonic states in colloidal CdSe quantum dots are assigned using excitonic state-resolved pump/probe spectroscopy. These experiments yield a direct test of the two prevailing approaches to quantum dot electronic structure: the effective mass and the atomistic approaches. The experimental results are in complete agreement with the atomistic approach, whereas the effective mass approach fails to assign the correct electron symmetries for higher excitonic states.
Magnetic domain characterizations of anisotropic-shaped MnAs nanoclusters position-controlled by selective-area metal-organic vapor phase epitaxy
Authors: Ito Shingo , Hara Shinjiroh , Wakatsuki Toshitomo , Fukui Takashi
Published: June 2009

The authors report the buildup fabrication and magnetic domain characterizations of anisotropic-shaped MnAs nanoclusters position-controlled on partially SiO2-masked GaAs (111)B substrates by selective-area metal-organic vapor phase epitaxy. Magnetic force microscopy reveals that both the symmetric- and anisotropic-shaped nanoclusters show spontaneous magnetization at room temperature. Some of the nanoclusters show a single magnetic domain, in which magnetized directions are along one of the a-axes of NiAs-type MnAs, after the external magnetic fields up to 3500 Gauss are applied in-plane. The magnetic domains are well controlled by introducing both magnetocrystalline and shape magnetic anisotropies in the anisotropic-shaped nanoclusters.
The contributions of the acoustic modes and optical modes to the primary pyroelectric coefficient of GaN
Authors: Yan W. S. , Zhang R. , Xie Z. L. , Xiu X. Q. , Zheng Y. D. , Liu Z. G. , Xu S. , He Z. H.
Published: June 2009

As competitive next generation pyroelectric sensors, the pyroelectricity of GaN has been investigated. The specific heat of the wurtzite GaN is calculated from the Raman-scattering data. The contributions of the acoustic modes and optical modes to the primary pyroelectric coefficient of GaN are calculated from 0 to 600 K. An explicit expression of the primary pyroelectric coefficient as a function of temperature is derived. It is found that the primary pyroelectric coefficient of GaN can be expressed as the sum of the Debye function and Einstein function. It is substantially different from that of conventional ferroelectrics-based pyroelectric devices which can be described only by the Einstein function.
Conformal array design with transformation electromagnetics
Authors: Popa Bogdan-Ioan , Allen Jeffery , Cummer Steven A.
Published: June 2009

We apply the theory of transformation electromagnetics to source arrays and show that a complex conformal antenna array can be made to behave like a geometrically different array when surrounded with a properly designed transformation electromagnetics medium. Numerical simulations are presented to show how a nonuniform circular array can be made to radiate and receive as a uniformly spaced linear array. In this way, transformation electromagnetics provides a method by which all of the advantages of simple arrays in array processing, such as beamforming, can be retained in an array whose elements are constrained to a complex geometry.
Genetic structure and phylogeography of freshwater shrimps (Macrobrachium australiense and Macrobrachium tolmerum): the role of contemporary and historical events
Authors: Sharma Suman , Hughes Jane M.
Published: June 2009

Freshwater species are expected to show higher levels of genetic structuring than those inhabiting estuarine or marine environments because it is difficult for freshwater species to move between river systems. Previous genetic studies of freshwater species from coastal streams in south-east Queensland had proposed that several of these streams had a common confluence relatively recently, when sea levels were lower ~10 000 years bp. The present study was undertaken to test this idea using two freshwater shrimp species, Macrobrachium australiense and Macrobrachium tolmerum. In M. australiense, there was a major phylogeographical break in the middle of the Sunshine Coast region that was expected to be homogeneous because these creeks may have had a shared confluence before entering the sea, possibly because of extremely limited dispersal abilities compounded over many generations. In M. tolmerum, there was evidence of a recent population expansion and also some evidence of limited gene flow between sites. This is explained by recent colonisation of the area and limited gene flow between river systems, despite the ability of this species to survive in brackish water conditions. The present study shows that even species that are taxonomically very close and that co-occur in the same habitats can have vastly different population structures.
Trophic links and riverine effects on food webs of pelagic fish of the north-western Black Sea
Authors: Bănaru Daniela , Harmelin-Vivien Mireille
Published: June 2009

Improving the knowledge of trophodynamics in coastal marine ecosystems is important for fisheries management. The present study was designed to assess the influence of Danube River inputs on Romanian coastal marine food webs of the European sprat (Sprattus sprattus), the European anchovy (Engraulis encrasicholus) and the horse mackerel (Trachurus mediterraneus). Gut content analyses coupled with carbon and nitrogen stable isotope analyses described food web variations with fish size, season and distance from the Danube delta. Sprats fed on zooplankton, horse mackerel fed on polychaetes and small fish, and anchovies had an intermediate diet. The δ13C and δ15N ratios and mean trophic levels increased from sprats to anchovies and then to horse mackerel. Season strongly influenced the δ15N values of the three fishes, with lower values in spring than in autumn linked to higher Danube inputs into coastal waters in spring during the flooding period. Fish condition was related to diet and environmental factors, with higher conditions recorded in the north area in autumn and in the south area in spring. Danube River inputs influenced the diet, stable isotope ratios and condition of the main commercial pelagic migratory fishes of the north-western Black Sea.
Contribution of organic matter sources to cyprinid fishes in the Chany Lake - Kargat River estuary, western Siberia
Authors: Kanaya Gen , Yadrenkina Elena N. , Zuykova Elena I. , Kikuchi Eisuke , Doi Hideyuki , Shikano Shuichi , Mizota Chitoshi , Yurlova Natalia I.
Published: June 2009

Although omnivorous cyprinid fish often dominate fish communities in shallow eutrophic lakes, their role in the food web is poorly known. In the present study, carbon sources of six cyprinid species were examined in a littoral freshwater habitat in a saline lake complex (Lake Chany, western Siberia, Russia) using stable isotope analyses (SIA). In this habitat, microalgae (phytoplankton and epiphytes), macrophytes and riparian vegetation comprised the major producer groups with distinctive δ13C values. Zooplankton and most benthic invertebrates functioned primarily as microalgae-based consumers, whereas the amphipod Gammarus lacustris depended largely on macrophytes or macrophyte-derived detritus. Cyprinids, Carassius carassius L., Car. auratus gibelio Bloch. and Abramis brama L., mainly utilised microalgae-derived carbon (δ13C-based isotope mixing model: 66–97%) via zooplanktonic trophic mediations. In contrast, Cyprinus carpio L., Leuciscus idus L. and Rutilus rutilus L. depended more on macrophytic and/or riparian production (52–80%) than on microalgal production. Observations and SIA of foregut contents indicated highly opportunistic feeding habits of R. rutilus and L. idus and preference for macrophytes. These results suggested that cyprinid fishes link pelagic, benthic and riparian food webs in this shallow, eutrophic lake ecosystem.
Longitudinal effects of a water supply reservoir (Tallowa Dam) on downstream water quality, substrate and riffle macroinvertebrate assemblages in the Shoalhaven River, Australia
Authors: Growns Ivor , Reinfelds Ivars , Williams Simon , Coade Geoff
Published: June 2009

Approximately 15% of the world’s total run-off is presently retained by more than 45 000 large dams. However, the extent of the downstream ecological impacts of those dams is rarely assessed. The longitudinal effects of a large reservoir on the substrate, water quality and riffle macroinvertebrate communities were examined between 0.5 and 18.3 km downstream of Tallowa Dam. The number of taxa and the Australian River Assessment Scheme observed v. expected score generally increased with increasing distance from the dam, average clast size decreased with increasing distance and water quality showed distinct longitudinal patterns. Classification of the macroinvertebrate assemblages identified two groups, one from riffles ~4 km downstream of the dam and one further downstream, suggesting the main impact occurs close to the dam. The difference between the two groups of riffles resulted mainly from the following macroinvertebrates, Edmundsiops (Baetidae), Hemigomphus (Gomphidae), Illiesoperla (Gripopterygidae), Physa (Physidae), Nannoplebia (Libellulidae) and Austrolimnius larvae (Elmidae), occurring less frequently in the near-dam riffles. Water quality was probably the main cause of the altered macroinvertebrate assemblage structure, not altered hydrology, a result attributable to the small operational capacity of Tallowa Dam relative to the annual inflow volumes.
Biogenic habitat on artificial structures: consequences for an intertidal predator
Authors: Jackson A. C.
Published: June 2009

With urbanisation, there is an increasing trend for artificial structures, such as seawalls, to replace natural habitats. The predatory mulberry whelk, Morula marginalba Blainville, is seldom observed on seawalls in Sydney Harbour, yet it is abundant on the rocky shores of south-eastern Australia. The Sydney rock oyster, Saccostrea glomerata Gould, is common on seawalls in Sydney Harbour, forming two types of crust, providing ‘elaborate’ or ‘simple’ habitats that differ in structure. Whelks were numerous on some seawalls with elaborate oyster crusts, but were sparse on walls with simple crusts. Thus, different types of crust, with different structure, may explain the differences in the numbers of whelks among seawalls. These different crusts may cause differences in dispersal and/or mortality. The structure of the habitat created by the oysters was manipulated on seawalls and the responses of M. marginalba were observed. Whelks emigrated more rapidly from simple than from elaborate crusts and more individuals moved into elaborate than into simple crusts. Decreases in the numbers of M. marginalba at larger scales, via mortality or emigration, did not differ between the crust types. The range of habitats that can be used by M. marginalba is extended because it can exploit the biogenic structure provided by oysters on artificial urban structures, which otherwise form unsuitable habitat.
A new conceptual model for the warm-water breakdown of the coral - algae endosymbiosis
Authors: Wooldridge Scott A.
Published: June 2009

The symbiosis between reef-building corals and their algae endosymbionts is sensitive to temperature stress, which makes coral reefs vulnerable to climate change. However, a precise understanding of the capacity for the symbiosis to adapt to climate change is currently restricted by the lack of coherent explanation for the set of cellular events leading to its warm-water breakdown (= coral bleaching). Here, a new coral bleaching model is proposed in which the triggering event is a disruption to the ‘dark’ photosynthetic reactions of the algae endosymbionts, primarily due to a limited availability of CO2 substrate around the Rubisco enzyme (ribulose-1,5-bisphosphate carboxylase). Paradoxically, this CO2-limiting condition may be enhanced by the modern increase in atmospheric CO2 partial pressure (pCO2). Importantly, the model delivers a new standpoint from which to explain: (i) upper thermal bleaching thresholds; and (ii) the mechanism underpinning endosymbiont shuffling. Overall, the model leaves little doubt as to the diminished stability and functioning (i.e. resilience) of the coral–algae endosymbiosis due to the rising pCO2 and warming trend in the upper ocean surface layer. It is concluded that whole-colony bleaching is the destructive endpoint to a suite of cellular processes that operate near continuously in modern symbiotic corals.
DNA evidence of whale sharks (Rhincodon typus) feeding on red crab (Gecarcoidea natalis) larvae at Christmas Island, Australia
Authors: Meekan M. G. , Jarman S. N. , McLean C. , Schultz M. B.
Published: June 2009

Whale sharks (Rhincodon typus) are thought to aggregate in nearshore waters around Christmas Island (105°37′E, 10o29′S) to consume the marine larvae of the endemic red land crab (Gecarcoidea natalis). However, there have been no direct observations of sharks feeding on crab larvae. Whale shark faeces were analysed using genetic testing to confirm the presence of crab larvae in their diet. Primers were designed for amplifying two Gecarcoidea natalis mitochondrial small-subunit (mtSSU) rDNA regions. Gel electrophoresis of polymerase chain reaction (PCR) products amplified from whale shark faecal DNA produced bands of the expected size for G. natalis templates. Specificity of both primer sets for G. natalis mtSSU rDNA was expected to be high from comparisons with mtSSU rDNA regions from closely related crabs and we confirmed their specificity empirically. The amplification of fragments from faecal DNA of the same size as those produced from G. natalis DNA indicates that the whale shark had been feeding on G. natalis and that enough of the crab DNA survived digestion to be detected by these PCRs. Our study provides further evidence that aggregations of whale sharks in coastal waters occur in response to ephemeral but predictable increases in planktonic prey.
Livestock and water: understanding the context based on the 'Comprehensive Assessment of Water Management in Agriculture'
Authors: Bossio Deborah
Published: June 2009

The recently completed ‘Comprehensive Assessment of Water Management in Agriculture’ (CA) assessed the benefits, costs and impacts of the past 50 years of water development. It highlighted important trends that frame the challenges in water resources management of today and into the future, and critically evaluated solutions that people have developed to cope with these challenges. Important past trends include increases in food production that have outpaced population growth, much of this due to a doubling of the global irrigated area between 1961 and 2003, and accompanying declines in the health of aquatic ecosystems resulting from demands for, and impacts of, water use in agriculture. The future will bring new pressures on water resources and ecosystems as demands from sectors other than agriculture increase (including water for biofuel production), populations rise and become more wealthy, which leads to demand for foods that are more water intensive to produce, and climate change increases uncertainty and risk in our agricultural systems. Modelling predictions and analysis of scenarios show that water demand may rise from between only 20 up to 90% over the next 50 years, depending on how we choose to manage water in agricultural systems in the future. Owing to the importance of meat in changing diets and the role of livestock in managing land degradation, livestock is central to many of the issues that will determine whether or not optimistic scenarios (minimised increased demand for agricultural water in the future) can be achieved. This paper briefly summarises the insights and results of the CA, and highlights the areas where livestock management is most closely related to major water challenges and global recommendations of the CA. The purpose of this introductory paper is to set the context within which the importance of enhancing livestock water productivity in mixed farming systems can be appreciated.
Livestock water productivity: implications for sub-Saharan Africa
Authors: Peden D. , Taddesse G. , Haileslassie A.
Published: June 2009

Water is essential for agriculture including livestock. Given increasing global concern that access to agricultural water will constrain food production and that livestock production uses and degrades too much water, there is compelling need for better understanding of the nature of livestock–water interactions. Inappropriate animal management along with poor cropping practices often contributes to widespread and severe depletion, degradation and contamination of water. In developed countries, diverse environmental organisations increasingly voice concerns that animal production is a major cause of land and water degradation. Thus, they call for reduced animal production. Such views generally fail to consider their context, applicability and implications for developing countries.
Two global research programs, the CGIAR ‘Comprehensive Assessment of Water Management and Agriculture’ and ‘Challenge Program on Water and Food’ have undertaken studies of the development, management and conservation of agricultural water in developing countries. Drawing on these programs, this paper describes a framework to systematically identify key livestock–water interactions and suggests strategies for improving livestock and water management especially in the mixed crop–livestock production systems of sub-Saharan Africa. In contrast to developed country experience, this research suggests that currently livestock water productivity compares favourably with crop water productivity in Africa. Yet, great opportunities remain to further reduce domestic animals’ use of water in the continent. Integrating livestock and water planning, development and management has the potential to help reduce poverty, increase food production and reduce pressure on the environment including scarce water resources. Four strategies involving technology, policy and institutional interventions can help achieve this. They are choosing feeds that require relatively little water, conserving water resources through better animal and land management, applying well known tools from the animal sciences to increase animal production, and strategic temporal and spatial provisioning of drinking water. Achieving integrated livestock–water development will require new ways of thinking about, and managing, water by water- and animal-science professionals.
Opportunities and limitations of food - feed crops for livestock feeding and implications for livestock - water productivity
Authors: Blümmel M. , Samad M. , Singh O. P. , Amede T.
Published: June 2009

The paper discusses the contribution of crop residues (CR) to feed resources in the context of the water productivity of CR in livestock feeding, using India as an example. It is argued that crop residues are already the single most important feed resource in many livestock production systems in developing countries and that increasing their contribution to livestock feeding needs to be linked to improving their fodder quality. Using examples from multi-dimensional crop improvement, it is shown that CR fodder quality of key crops such as sorghum, rice and groundnut can be improved by genetic enhancement without detriment to grain and pod yields. Improving crop residue quality through genetic enhancement, agronomic and management interventions and strategic supplementation could improve water productivity of farms and systems considerably. The draw-backs of CR based feeding regimes are also pointed out, namely that they result in only moderate levels of livestock productivity and produce higher greenhouse gas emissions than are observed under feeding regimes that are based on high quality forages and concentrates. It is argued that feed metabolisable energy (ME) content should be used as an important determinant of livestock productivity; water requirement for feed and fodder production should be related to a unit of feed ME rather than feed bulk. The paper also revisits data from the International Water Management Institute (IWMI) work on livestock–water productivity in the Indian state of Gujarat, showing that water input per unit ME can vary several-fold in the same feed depending on where the feed is produced. Thus, the production of one mega joule of ME from alfalfa required 12.9 L of irrigation-derived water in south Gujarat but 50.7 L of irrigation-derived water in north Gujarat. Wheat straw in south Gujarat required 20.9 L of irrigation-derived water for 1 MJ ME and was in this instance less water use efficient than alfalfa. We conclude that water use efficiency across feed and fodder classes (for example crop residue v. planted forages) and within a feed is highly variable. Feeding recommendations should be made according to specific water use requirement per unit ME in a defined production system.
Impacts of micro-basin water harvesting structures in improving vegetative cover in degraded hillslope areas of north-east Ethiopia
Authors: Derib Sisay Demeku , Assefa Tewodros , Berhanu Belete , Zeleke Gete
Published: June 2009

Water is one of the most important entry points to improve rural livelihoods in drought affected areas of the north-eastern Amhara region in Ethiopia. Various attempts have been made to overcome this problem by making use of different water harvesting structures. However, the choice of structures has been difficult because of a lack of empirical evidence on the relative effectiveness of the different structures.
An experiment was conducted from 2002 to 2004 to compare and evaluate three different water harvesting structures (eye-brow basin, half-moon and trench) against the normal seedling plantation practice by farmers (normal pit) as a control. Data on root collar diameter (RCD), diameter at breast height (DBH), height and survival rate of Acacia saligna tree seedlings was collected at 3-month intervals after planting and annual grass biomass production was also measured. Trench and eye-brow basin structures produced 68, 95, 52 and 44% increases in RCD, DBH, height and survival rate, respectively, 15 months after planting compared with the normal pit. Trench structures increased grass biomass by 41.1% compared with normal pits.
Eye-brow basins are recommended on hillsides where stone is available while trenchs could be used where stone is scarce. The results indicated that well designed water harvesting micro-basin structures can mitigate the effect of dry spell shocks on tree seedling performance and land cover rehabilitation. They were also very effective in increasing grass biomass production indicating the potential for improving livestock feed on the available barren hillsides.
Harnessing benefits from improved livestock water productivity in crop–livestock systems of sub-Saharan Africa: synthesis
Authors: Amede Tilahun , Descheemaeker Katrien , Peden Don , van Rooyen Andre
Published: June 2009

The threat of water scarcity in sub-Saharan Africa is real, due to the expanding agricultural needs, climate variability and inappropriate land use. Livestock keeping is the fastest growing agricultural sector, partly because of increasing and changing demands for adequate, quality and diverse food for people, driven by growing incomes and demographic transitions. Besides the economic benefits, rising livestock production could also deplete water and aggravate water scarcity at local and global scales. The insufficient understanding of livestock–water interactions also led to low livestock productivity, impeded sound decision on resources management and undermined achieving positive returns on investments in agricultural water across sub-Saharan Africa. Innovative and integrated measures are required to improve water productivity and reverse the growing trends of water scarcity. Livestock water productivity (LWP), which is defined as the ratio of livestock outputs to the amount of water depleted, could be improved through: (i) raising the efficiency of the water inputs by integrating livestock with crop, water and landscape management policies and practices. Improving feed water productivity by maximising transpiration and minimising evaporation and other losses is critical; (ii) increasing livestock outputs through improved feed management, veterinary services and introducing system-compatible breeds; and (iii) because livestock innovation is a social process, it is not possible to gain LWP improvements unless close attention is paid to policies, institutions and their associated processes. Policies targeting infrastructure development would help livestock keepers secure access to markets, veterinary services and knowledge. This paper extracts highlights from various papers presented in the special issue of The Rangeland Journal on technologies and practices that would enable improving water productivity at various scales and the premises required to reverse the negative trends of water depletion and land degradation.
The current refugial rainforests of Sundaland are unrepresentative of their biogeographic past and highly vulnerable to disturbance
Authors: Cannon Charles H. , Morley Robert J. , Bush Andrew B. G.
Published: June 2009

Understanding the historical dynamics of forest communities is a critical element for accurate prediction of their response to future change. Here, we examine evergreen rainforest distribution in the Sunda Shelf region at the last glacial maximum (LGM), using a spatially explicit model incorporating geographic, paleoclimatic, and geologic evidence. Results indicate that at the LGM, Sundaland rainforests covered a substantially larger area than currently present. Extrapolation of the model over the past million years demonstrates that the current “island archipelago” setting in Sundaland is extremely unusual given the majority of its history and the dramatic biogeographic transitions caused by global deglaciation were rapid and brief. Compared with dominant glacial conditions, lowland forests were probably reduced from approximately 1.3 to 0.8 × 10
6
km
2
while upland forests were probably reduced by half, from approximately 2.0 to 1.0 × 10
5
km
2
. Coastal mangrove and swamp forests experienced the most dramatic change during deglaciations, going through a complete and major biogeographic relocation. The Sundaland forest dynamics of fragmentation and contraction and subsequent expansion, driven by glacial cycles, occur in the opposite phase as those in the northern hemisphere and equatorial Africa, indicating that Sundaland evergreen rainforest communities are currently in a refugial stage. Widespread human-mediated reduction and conversion of these forests in their refugial stage, when most species are passing through significant population bottlenecks, strongly emphasizes the urgency of conservation and management efforts. Further research into the natural process of fragmentation and contraction during deglaciation is necessary to understand the long-term effect of human activity on forest species.
Enhanced humoral immune responses against T-independent antigens in Fcα/μR-deficient mice
Authors: Honda Shin-ichiro , Kurita Naoki , Miyamoto Akitomo , Cho Yukiko , Usui Kenta , Takeshita Kie , Takahashi Satoru , Yasui Teruhito , Kikutani Hitoshi , Kinoshita Taroh , Fujita Teizo , Tahara-Hanaoka Satoko , Shibuya Kazuko , Shibuya Akira
Published: June 2009

IgM is an antibody class common to all vertebrates that plays a primary role in host defenses against infection. Binding of IgM with an antigen initiates the complement cascade, accelerating cellular and humoral immune responses. However, the functional role of the Fc receptor for IgM in such immune responses remains obscure. Here we show that mice deficient in Fcα/μR, an Fc receptor for IgM expressed on B cells and follicular dendritic cells (FDCs), have enhanced germinal center formation and affinity maturation and memory induction of IgG3+B cells after immunization with T-independent (TI) antigens. Moreover, Fcα/μR-deficient mice show prolonged antigen retention by marginal zone B (MZB) cells and FDCs. In vitro studies demonstrate that interaction of the IgM immune complex with Fcα/μR partly suppress TI antigen retention by MZB cells. We further show that downregulation of complement receptor (CR)1 and CR2 or complement deprivation by in vivo injection with anti-CR1/2 antibody or cobra venom factor attenuates antigen retention by MZB cells and germinal center formation after immunization with TI antigens inFcα/μR−/−mice. Taken together, these results suggest that Fcα/μR negatively regulates TI antigen retention by MZB cells and FDCs, leading to suppression of humoral immune responses against T-independent antigens.
Secretion of amyloidogenic gelsolin progressively compromises protein homeostasis leading to the intracellular aggregation of proteins
Authors: Page Lesley J. , Suk Ji Young , Bazhenova Lyudmila , Fleming Sheila M. , Wood Malcolm , Jiang Yun , Guo Ling T. , Mizisin Andrew P. , Kisilevsky Robert , Shelton G. Diane , Balch William E. , Kelly Jeffery W.
Published: June 2009

Familial amyloidosis of Finnish type (FAF) is a systemic amyloid disease associated with the deposition of proteolytic fragments of mutant (D187N/Y) plasma gelsolin. We report a mouse model of FAF featuring a muscle-specific promoter to drive D187N gelsolin synthesis. This model recapitulates the aberrant endoproteolytic cascade and the aging-associated extracellular amyloid deposition of FAF. Amyloidogenesis is observed only in tissues synthesizing human D187N gelsolin, despite the presence of full-length D187N gelsolin and its 68-kDa cleavage product in blood—demonstrating the importance of local synthesis in FAF. Loss of muscle strength was progressive in homozygous D187N gelsolin mice. The presence of misfolding-prone D187N gelsolin appears to exacerbate the age-associated decline in cellular protein homeostasis (proteostasis), reflected by the intracellular deposition of numerous proteins, a characteristic of the most common degenerative muscle disease of aging humans, sporadic inclusion body myositis.
Biodesign of a renal-protective peptide based on alternative splicing of B-type natriuretic peptide
Authors: Pan Shuchong , Chen Horng H. , Dickey Deborah M. , Boerrigter Guido , Lee Candace , Kleppe Laurel S. , Hall Jennifer L. , Lerman Amir , Redfield Margaret M. , Potter Lincoln R. , Burnett John C. , Simari Robert D.
Published: June 2009

Alternative RNA splicing may provide unique opportunities to identify drug targets and therapeutics. We identified an alternative spliced transcript for B-type natriuretic peptide (BNP) resulting from intronic retention. This transcript is present in failing human hearts and is reduced following mechanical unloading. The intron-retained transcript would generate a unique 34 amino acid (aa) carboxyl terminus while maintaining the remaining structure of native BNP. We generated antisera to this carboxyl terminus and identified immunoreactivity in failing human heart tissue. The alternatively spliced peptide (ASBNP) was synthesized and unlike BNP, failed to stimulate cGMP in vascular cells or vasorelax preconstricted arterial rings. This suggests that ASBNP may lack the dose-limiting effects of recombinant BNP. Given structural considerations, a carboxyl-terminal truncated form of ASBNP was generated (ASBNP.1) and was determined to retain the ability of BNP to stimulate cGMP in canine glomerular isolates and cultured human mesangial cells but lacked similar effects in vascular cells. In a canine-pacing model of heart failure, systemic infusion of ASBNP.1 did not alter mean arterial pressure but increased the glomerular filtration rate (GFR), suppressed plasma renin and angiotensin, while inducing natriuresis and diuresis. Consistent with its distinct in vivo effects, the activity of ASBNP.1 may not be explained through binding and activation of NPR-A or NPR-B. Thus, the biodesigner peptide ASBNP.1 enhances GFR associated with heart failure while lacking the vasoactive properties of BNP. These findings demonstrate that peptides with unique properties may be designed based on products of alternatively splicing.
Assembly and organization processes in DNA-directed colloidal crystallization
Authors: Macfarlane Robert J. , Lee Byeongdu , Hill Haley D. , Senesi Andrew J. , Seifert Soenke , Mirkin Chad A.
Published: June 2009

We present an analysis of the key steps involved in the DNA-directed assembly of nanoparticles into crystallites and polycrystalline aggregates. Additionally, the rate of crystal growth as a function of increased DNA linker length, solution temperature, and self-complementary versus non-self-complementary DNA linker strands (1- versus 2-component systems) has been studied. The data show that the crystals grow via a 3-step process: an initial “random binding” phase resulting in disordered DNA-AuNP aggregates, followed by localized reorganization and subsequent growth of crystalline domain size, where the resulting crystals are well-ordered at all subsequent stages of growth.
A Bayesian model predicts the response of axons to molecular gradients
Authors: Mortimer Duncan , Feldner Julia , Vaughan Timothy , Vetter Irina , Pujic Zac , Rosoff William J. , Burrage Kevin , Dayan Peter , Richards Linda J. , Goodhill Geoffrey J.
Published: June 2009

Axon guidance by molecular gradients plays a crucial role in wiring up the nervous system. However, the mechanisms axons use to detect gradients are largely unknown. We first develop a Bayesian “ideal observer” analysis of gradient detection by axons, based on the hypothesis that a principal constraint on gradient detection is intrinsic receptor binding noise. Second, from this model, we derive an equation predicting how the degree of response of an axon to a gradient should vary with gradient steepness and absolute concentration. Third, we confirm this prediction quantitatively by performing the first systematic experimental analysis of how axonal response varies with both these quantities. These experiments demonstrate a degree of sensitivity much higher than previously reported for any chemotacting system. Together, these results reveal both the quantitative constraints that must be satisfied for effective axonal guidance and the computational principles that may be used by the underlying signal transduction pathways, and allow predictions for the degree of response of axons to gradients in a wide variety of in vivo and in vitro settings.
A unique virus release mechanism in the Archaea
Authors: Bize Ariane , Karlsson Erik A. , Ekefjärd Karin , Quax Tessa E. F. , Pina Mery , Prevost Marie-Christine , Forterre Patrick , Tenaillon Olivier , Bernander Rolf , Prangishvili David
Published: June 2009

Little is known about the infection cycles of viruses infecting cells from Archaea, the third domain of life. Here, we demonstrate that the virions of the archaeal
Sulfolobus islandicus
rod-shaped virus 2 (SIRV2) are released from the host cell through a mechanism, involving the formation of specific cellular structures. Large pyramidal virus-induced protrusions transect the cell envelope at several positions, rupturing the S-layer; they eventually open out, thus creating large apertures through which virions escape the cell. We also demonstrate that massive degradation of the host chromosomes occurs because of virus infection, and that virion assembly occurs in the cytoplasm. Furthermore, intracellular viral DNA is visualized by flow cytometry. The results show that SIRV2 is a lytic virus, and that the host cell dies as a consequence of elaborated mechanisms orchestrated by the virus. The generation of specific cellular structures for a distinct step of virus life cycle is known in eukaryal virus-host systems but is unprecedented in cells from other domains.
Decoupling of the brain's default mode network during deep sleep
Authors: Horovitz Silvina G. , Braun Allen R. , Carr Walter S. , Picchioni Dante , Balkin Thomas J. , Fukunaga Masaki , Duyn Jeff H.
Published: June 2009

The recent discovery of a circuit of brain regions that is highly active in the absence of overt behavior has led to a quest for revealing the possible function of this so-called
default-mode network
(DMN). A very recent study, finding similarities in awake humans and anesthetized primates, has suggested that DMN activity might not simply reflect ongoing conscious mentation but rather a more general form of network dynamics typical of complex systems. Here, by performing functional MRI in humans, it is shown that a natural, sleep-induced reduction of consciousness is reflected in altered correlation between DMN network components, most notably a reduced involvement of frontal cortex. This suggests that DMN may play an important role in the sustenance of conscious awareness.
Transcription coactivator SAYP combines chromatin remodeler Brahma and transcription initiation factor TFIID into a single supercomplex
Authors: Vorobyeva Nadezhda E. , Soshnikova Nataliya V. , Nikolenko Julia V. , Kuzmina Julia L. , Nabirochkina Elena N. , Georgieva Sofia G. , Shidlovskii Yulii V.
Published: June 2009

Transcription activation by RNA polymerase II is a complicated process driven by combined, precisely coordinated action of a wide array of coactivator complexes, which carry out chromatin-directed activities and nucleate the assembly of the preinitiation complex on the promoter. Using various techniques, we have shown the existence of a stable coactivator supercomplex consisting of the chromatin-remodeling factor Brahma (SWI/SNF) and the transcription initiation factor TFIID, named BTFly (Brahma and TFIID in one assembly). The coupling of Brahma and TFIID is mediated by the SAYP factor, whose evolutionarily conserved activation domain SAY can directly bind to both BAP170 subunit of Brahma and TAF5 subunit of TFIID. The integrity of BTFly is crucial for its ability to activate transcription. BTFly is distributed genome-wide and appears to be a means of effective transcription activation.