bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unification of reaction pathway and kinetic scheme for N
2
reduction catalyzed by nitrogenase
Authors: Lukoyanov Dmitriy , Yang Zhi-Yong , Barney Brett M. , Dean Dennis R. , Seefeldt Lance C. , Hoffman Brian M. 
Published: March 2012

Nitrogenase catalyzes the reduction of N
2
and protons to yield two NH
3
and one H
2
. Substrate binding occurs at a complex organo-metallocluster called FeMo-cofactor (FeMo-co). Each catalytic cycle involves the sequential delivery of eight electrons/protons to this cluster, and this process has been framed within a kinetic scheme developed by Lowe and Thorneley. Rapid freezing of a modified nitrogenase under turnover conditions using diazene, methyldiazene (HN = N-CH
3
), or hydrazine as substrate recently was shown to trap a common

intermediate, designated

I

. It was further concluded that the two N-atoms of N
2
are hydrogenated alternately (“Alternating” (

A

) pathway). In the present work, Q-band CW EPR and
95
Mo ESEEM spectroscopy reveal such samples also contain a common intermediate with FeMo-co in an integer-spin state having a ground-state “non-Kramers” doublet. This species, designated

H

, has been characterized by ESEEM spectroscopy using a combination of
14,15
N isotopologs plus
1,2
H isotopologs of methyldiazene. It is concluded that:

H

has NH
2
bound to FeMo-co and corresponds to the penultimate intermediate of N
2
hydrogenation, the state formed after the accumulation of seven electrons/protons and the release of the first NH
3
;

I

corresponds to the final intermediate in N
2
reduction, the state formed after accumulation of eight electrons/protons, with NH
3
still bound to FeMo-co prior to release and regeneration of resting-state FeMo-co. A proposed unification of the Lowe-Thorneley kinetic model with the “prompt” alternating reaction pathway represents a draft mechanism for N
2
reduction by nitrogenase.
Managing invasive species in heterogeneous ecosystems.
Authors: Brown J. R. , Bestelmeyer B. T. 
Published: March 2012

Abstract

In this chapter, we first discuss the challenge of managing invasive species in complex landscapes. In particular, how managing invasive species in wildland environments differs from more intensively managed systems, such as croplands, where the spatiotemporal relationships are much more clearly defined. Then we present and demonstrate the use of ecological sites (soil-based landscape subunits) and state-and-transition models (graphic and text descriptions of soil: vegetation dynamics) as a means of organizing and synthesizing information about plant community and landscape susceptibility to invasion. Managing invasive plants in complex landscapes, ecological sites and state and transition models, and applying ecological site information to invasive species management are also discussed.
Resource pool dynamics: conditions that regulate species interactions and dominance.
Authors: Leffler A. J. , Ryel R. J. 
Published: March 2012

Abstract

In this chapter we detail resource pools as a common currency for species interactions and demonstrate that under standing how plants modify resource availability for other species can lead to an improved framework for making decisions to manage invasive species. The resource pools and fluxes, plant modification of resource pools, modification of a resource pool by one species, species in a community that do not rely on identical resource pools, interactions among species mediated by resource pools, resource pool dynamics and invasive species, managing resource pools to influence invasive plant abundance, and management scenarios are discussed.
The effects of plant-soil feedbacks on invasive plants: mechanisms and potential management options.
Authors: Eviner V. T. , Hawkes C. V. 
Published: March 2012

Abstract

In this chapter, we explore the mechanisms driving plant-soil feedbacks in invaded systems, and potential management tools to alter these feedbacks to be more beneficial to natives over invasive species. The role of plant-soil feedbacks in shaping plant communities and plant invasions, invader plant-soil feedbacks enhance resilience of invaded state, mechanisms of feedbacks, and potential management tools (litter, allelochemicals, soil microbial community, nitrogen, and soil salinity), disturbance as an important feedback pathway, and the challenges in understanding and managing feedbacks are discussed.
Revegetation: using current technologies and ecological knowledge to manage site availability, species availability, and species performance.
Authors: Mangold J. M. 
Published: March 2012

Abstract

This chapter briefly discusses the ecological theory for revegetation. Then, current revegetation strategies, limitations of those strategies, and new approaches for revegetation will be described in the context of site availability, species availability, and species performance. The ecological theory behind the necessity for revegetation, current strategies for revegetating invasive-plant dominated plant communities, limitations of current strategies and application of ecological understanding, new approaches for revegetation that integrate our best understanding of ecological processes are also discussed.
The effects of alternative systems on disease and health of poultry.
Authors: Lister S. , Nijhuis B. van 
Published: March 2012

Abstract

Poultry health management is a pivotal component of successful poultry production. Disease and its effects on poultry health can damage productive performance and have an adverse effect on bird welfare and food safety. A whole host of factors can affect disease incidence and its impact on poultry health. These include the prevalence and interaction of many pathogens, availability and use of vaccines and medicines, standards of husbandry and management and levels of stockmanship. One area with potential to have the most dramatic influence is the birds' environment and how the birds respond to it. This impact has been well known throughout the development of the global poultry industry as it adapted to varying climates and market requirements. This involved considerable advances in technology and husbandry techniques. The first major changes tended to intensify poultry production. As such systems became the norm, they have often been described as 'conventional'. Key drivers in poultry production have changed in recent years including a re-evaluation of the welfare impact of such production systems for both egg laying and meat birds. Part of this has been some move away from conventional systems and a re-introduction of more traditional systems or the development of novel alternative systems. The list of diseases that can affect poultry is the same regardless of the system of production. However, the clinical effects of those disease challenges and impacts on health, performance and welfare can be specific to a particular system. In order to ensure health and welfare is maintained, the interaction of the bird with the environment and the effect this can have on poultry health and the bird's response to disease challenges must be understood.
Production systems for laying hens and broilers and risk of human pathogens.
Authors: Hoorebeke S. van , Dewulf J. , Immerseel F. van , Jorgensen F. 
Published: March 2012

Abstract

There is evidence that the type of production systems used for laying hens and broilers can affect the likelihood of the chickens being colonized by human pathogens. The most significant public health risk associated with layers is transmission of Salmonella to humans via eggs. Based on experimental and epidemiological data, however, it seems unlikely that the move from conventional cages to enriched cages and non-cage systems will result in an increase in the prevalence and/or shedding of Salmonella in laying hen flocks. Studies on broiler chickens suggest that free range and organic flocks are significantly more likely to be positive for Campylobacter at slaughter in comparison with first depopulated batches of conventionally reared broilers. Data in relation to broiler rearing system and the likelihood of birds being infected by other pathogens including Salmonella are scarce but there is no significant evidence to suggest that organic and free range broilers are more likely to be infected with Salmonella than are conventionally reared ones. There is some evidence for a higher level of antibiotic-resistant Campylobacter strains in conventional broilers compared with those found in organic ones and other antibiotic-resistant human pathogens are also more commonly isolated from conventionally reared broilers.
Technology and programmes for sustainable improvement of village poultry production.
Authors: Besbes B. , Thieme O. , Rota A. , Guèye E. F. , Alders R. G. 
Published: March 2012

Abstract

Although the commercial poultry sub-sector has reached a dominating position globally during the last three decades, village poultry production is still very important in most developing countries. Village poultry makes up more than 80% of the poultry stocks in many of the countries of Africa, Asia Pacific and Latin America. The village poultry sub-sector contributes significantly to food self-sufficiency, poverty alleviation and gender empowerment. It is a noticeable source of employment and well-being, especially for disadvantaged groups and in less-favoured areas. Despite many constraints, including high mortality from diseases and poor nutrition, significant improvements can be achieved through well-designed development programmes that endow the different actors dealing with village poultry with the necessary knowledge, skills and resources. Beyond this need for substantial improvement in human and institutional capacity building, planners and policy makers should be sensitized to recognize the significance and potentials of village poultry production. This chapter highlights the importance of village poultry production as a tool for poverty reduction, food security and gender empowerment in developing countries. It identifies the development objectives for such production systems and their contributions to meeting the Millennium Development Goals. It reviews the options, strategies and technologies that have been used to achieve these objectives and draws a few lessons.
Production systems for waterfowl.
Authors: Guémené D. , Shi Z. D. , Guy G. 
Published: March 2012

Abstract

Ducks and geese, which represent up to 7% of world poultry production, are raised for meat production, eggs, foie gras, down and feathers. Asia represents more than 80% of total waterfowl production, with China being the most important, and Europe accounting for around 13%. Traditional rearing conditions differ widely across the world, due to various species and breeds, environmental, cultural backgrounds and production conditions and objectives. Nevertheless, due to growing involvement of Western duck breeding companies, the demand for good production performances and high economic returns, more uniformity has been observed in recent years. However, demands for alternative rearing systems are emerging although, depending upon the country, the significance of alternative systems differs. Indeed, while this trend is exemplified by the ban of some cage systems and the development of free range systems in Europe, it is illustrated by the recent placement of duck layers for table eggs in conventional cages and the placement of an increasing number of geese in lightproof barns under a control photoperiod to get out-of-season production in China. These few examples illustrate the different uses and meanings of the term 'alternative system' in Eastern and Western countries.
Furnished cages for laying hens.
Authors: Elson H. A. , Tauson R. 
Published: March 2012

Abstract

Furnished cages (FCs) were conceived over 30 years ago when the welfare deficiencies of barren conventional ones were realized. Their use was intended to enhance hens' behavioural repertoire and welfare without the disadvantages of non-cage and extensive housing. Since then their design has been refined and improved, resulting in much improved performance and hen welfare. Group size has been an important consideration, especially in relation to variation in damaging pecking in differing genotypes with or without beak treatment. Regulations on the latter vary from country to country and have affected design, group size and management. The trend has been to move from furnished cages for small groups of hens (FCSs), used mainly in Scandinavia, to furnished cages for medium/large groups (FCMs/FCLs) subsequently developed in other countries. The three group sizes have generally performed well under good management. Interventions such as beak trimming and controlled light intensity are most often applied in FCLs and to brown genotypes. Large-scale studies, in which performance and welfare have been compared across all currently available systems, show that they are at least as good in FCs as in any other system, and probably superior. Council Directive 1999/74/EC, which required the demise of all conventional cages in the European Union by 2012, has accelerated the move into FCs and it seems likely that the majority of laying hens in Europe will be housed in them for the foreseeable future, with the aim of enhancing laying hen welfare. However, FCs have potential for further improvement; this chapter suggests some possible developments.
Is there a future for alternative production systems?
Authors: Sandilands V. , Hocking P. M. 
Published: March 2012

Abstract

The trend towards alternative systems of production for poultry meat and eggs in the developed economies is paralleled by moves to increase intensification in the developing world. Alongside these changes is the clearly identified imperative to feed an increasingly large and affluent human population in a sustainable manner. Pressure to intensify from the economics of production continue to favour intensive systems but legislation to ban the most intensive systems of production for animal welfare concerns will have a major effect on the way poultry are kept. The least intensive of alternative systems may be associated with greater behavioural freedom for the animals, but can have a significantly greater environmental impact than intensive systems, higher mortality and possibly reduced product quality. In general there is a need for more evidence on all of the inputs and outputs from different systems and economic conditions. Such analyses will allow policy makers to identify areas that need to be changed or modified by appropriate action and by suitably targeted research.
Antioxidant properties
in vitro
and
in vivo
: realistic assessments of efficacy of plant extracts.
Authors: Tsao Rong Tsao Rong , Li HongYan Li HongYan 
Published: March 2012

Abstract

Diets or plant extracts (food supplements) rich in phytochemical antioxidants are able to reduce the incidence of non-communicable diseases such as cardiovascular diseases, diabetes, stroke and different types of cancer. Antioxidant properties are key criteria for the evaluation of the health-beneficial potential of a food, as a consequence, accurately assessing the antioxidant properties becomes critical. The various
in vitro
assay methods are important tools available for evaluating the antioxidant potential of foods. They are simple and can provide highly reproducible results for comparison of the different foods. A brief summary of the
in vitro
assay methods and
in vivo
commonly agreed key biomarkers and evidences is presented in this review. However, high antioxidant properties
in vitro
does not always lead to increased antioxidant values
ex vivo
or
in vivo
. Many factors can affect this, among them stability to stand the physicochemical and enzymatic degradation in the gastrointestinal tract, and bioavailability to the various tissues or organs of these phytochemicals are perhaps most important.
Effects of Media Ingredient Substitution and Comparison of Growth of Flavobacterium psychrophilum among Four Media
Authors: Oplinger Randall W. , Wagner Eric J. 
Published: March 2012

Abstract
The etiological agent of bacterial cold-water disease, Flavobacterium psychrophilum, can cause significant losses of salmonid fishes in aquaculture facilities. Few studies describing the value of media components on the growth of F. psychrophilum are available in the literature. We therefore conducted a study that began with the standard enriched Anacker-Ordal broth (EAO) and over the course of multiple iterations evaluated the effects of various media supplements by adding or subtracting them from the base EAO medium. Different media formulations were made, and samples were removed from each broth formulation every 24 h for 72 h. From those samples we determined bacterial density by measuring absorbance values with a spectrophotometer. The medium with the highest absorbance value from one iteration was used as the base medium in the next iteration. Using this iterative approach, we determined that sodium acetate, calcium chloride, and magnesium sulfate inhibit growth and that maltose has no effect on the proliferation of the bacterium. The addition of skimmed milk (0.2%) and horse serum (1%) appears to provide a slight improvement in bacterial proliferation. Variations in agar concentration had no effect on the growth of the bacterium. Even though the addition and removal of some ingredients increased the mean absorbance values, the benefit of these substitutions was not significant. Even so, we found that the growth of F. psychrophilum in EAO was better than that in two other widely used media: tryptone-yeast extract salts and maltose infused tryptone-yeast extract salts.
Received August 1, 2011; accepted December 6, 2011
Resonant x-ray diffraction: multipole interpretation
Authors: Matteo Sergio Di 
Published: March 2012

Abstract
The aim of this work is to provide a critical review of the multipole interpretation of resonant x-ray diffraction. After a brief historical introduction, we focus on the general formalism of electromagnetic multipole expansion in condensed matter. We then introduce the anomalous scattering amplitude from perturbation theory in the low-energy limit of the Dirac Hamiltonian. Finally, we merge the two previous sections by showing how the anomalous scattering amplitude can be interpreted in terms of electric and magnetic multipoles.
Some examples are then discussed, concerning the electric quadrupole in manganites, ‘exotic’ polar and axial toroidal multipoles in transition-metal oxides and polarization analysis allowing the disentanglement of nearby-lying multipoles in the energy spectrum.
Photoluminescence quantum efficiency and energy transfer of ErRE silicate (RE = Y, Yb) thin films
Authors: Wang B , Wang X J , Dood M J A de , Guo R M , Wang L , Vanhoutte M , Michel J , Kimerling L C , Zhou Z 
Published: March 2012

Abstract
Photoluminescence quantum efficiency and energy transfer were studied in ErRE (RE = Y, Yb) silicate thin films. For the first time, we experimentally determined the radiative/non-radiative decay rates of ErYb and ErY silicates and obtained photoluminescence quantum efficiencies of 0.28 ± 0.08 and 0.39 ± 0.13, respectively. Energy transfer between Yb and Er in ErYb silicate was investigated by comparing the effective excitation cross sections of ErYb and ErY silicate. At different pumping wavelengths, forward and backward energy transfer caused by the presence of Yb was experimentally demonstrated.
Thermodynamic and transport properties of two-temperature lithium plasmas
Authors: Wang Hai-Xing , Chen Shi-Qiang , Chen Xi 
Published: March 2012

Abstract
Thermodynamic and transport properties of two-temperature lithium plasmas are calculated for the pressure range from 0.0001 to 1 atm, electron temperatures from 1000 to 40 000 K and the electron/heavy particle ratio from 1 to 5. The calculated results are presented concerning the variation with the electron temperature of the plasma composition, specific enthalpy, specific heat, viscosity, electrical conductivity, thermal conductivity and diffusion coefficient with the gas pressure and electron/heavy-particle temperature ratio as the parameters. The effects of gas pressure and electron/heavy-particle temperature ratio on lithium plasma properties are discussed in terms of the variation of gas ionization degree with gas pressure and temperature. For the special case with gas temperature below 10 000 K and without accounting for gas ionization, the present calculated results about lithium viscosity and thermal conductivity at atmospheric pressure are consistent with those reported in the literature.
The novel virulence‐related gene nlxA in the lipopolysaccharide cluster of Xanthomonas citri ssp. citri is involved in the production of lipopolysaccharide and extracellular polysaccharide, motility, biofilm formation and stress resistance
Authors: YAN QING , HU XIUFANG , WANG NIAN 
Published: March 2012

SUMMARYLipopolysaccharide (LPS) is an important virulence factor of Xanthomonas citri ssp. citri, the causative agent of citrus canker disease. In this research, a novel gene, designated as nlxA (novel LPS cluster gene of X. citri ssp. citri), in the LPS cluster of X. citri ssp. citri 306, was characterized. Our results indicate that nlxA is required for O‐polysaccharide biosynthesis by encoding a putative rhamnosyltransferase. This is supported by several lines of evidence: (i) NlxA shares 40.14% identity with WsaF, which acts as a rhamnosyltransferase; (ii) sodium dodecylsulphate‐polyacrylamide gel electrophoresis analysis showed that four bands of the O‐antigen part of LPS were missing in the LPS production of the nlxA mutant; this is also consistent with a previous report that the O‐antigen moiety of LPS of X. citri ssp. citri is composed of a rhamnose homo‐oligosaccharide; (iii) mutation of nlxA resulted in a significant reduction in the resistance of X. citri ssp. citri to different stresses, including sodium dodecylsulphate, polymyxin B, H2O2, phenol, CuSO4 and ZnSO4. In addition, our results indicate that nlxA plays an important role in extracellular polysaccharide production, biofilm formation, stress resistance, motility on semi‐solid plates, virulence and in planta growth in the host plant grapefruit.
A before and after study assessing the impact of a new model for recognizing and responding to early signs of deterioration in an acute hospital
Authors: McDonnell Ann , Tod Angela , Bray Kate , Bainbridge Derek , Adsetts Dawn , Walters Stephen 
Published: March 2012

AbstractAim.  To evaluate the impact of a new model for the detection and management of deteriorating patients on knowledge and confidence of nursing staff in an acute hospital.Background.  International evidence shows that clinical deterioration is not always recognized or acted on by nurses. The use of physiological track and trigger scoring systems accompanied by a graded response strategy has been recommended to monitor all adult patients in acute UK hospitals. However, little is known about the impact of these new systems in practice.Design.  A single centre, mixed methods before‐and‐after study.Methods.  A mixed methods before‐and‐after study, set in a district general hospital in England, in 2009, including a survey (n = 213) and qualitative interviews (n = 15) with nursing staff. The questionnaire examined knowledge and confidence in recognition and management of deteriorating patients 6 weeks before and after an intervention which included training, new observation charts and a new track and trigger system. Interviews further explored participants’ perspectives. Comparisons were made between registered and unregistered nurses.Results.  Following the intervention, knowledge, and confidence to recognize and manage deteriorating patients increased; the number of concerns were reduced. Scores were higher for registered than unregistered nurses before and after the intervention. Interviews confirmed these findings and provided detail on how nurses felt the new system had improved practice.Conclusion.  The new model had a positive impact on the self‐assessed knowledge and confidence of registered and unregistered nurses. Similar initiatives should take into account the clinical context and tailor training packages accordingly.