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Impact of lime, nitrogen and plant species on bacterial community structure in grassland microcosms
Get PDFA microcosm-based approach was used to study
impacts of plant and chemical factors on the bacterial
community structure of an upland acidic grassland
soil. Seven perennial plant species typical of both
natural, unimproved (
Nardus stricta
,
Agrostis capillaris
,
Festuca ovina
and
F. rubra
) and fertilized,
improved (
Holcus lanatus, Lolium perenne
and
Trifolium
repens
) grasslands were either left unamended
or treated with lime, nitrogen, or lime plus nitrogen in
a 75-day glasshouse experiment. Lime and nitrogen
amendment were shown to have a greater effect on
microbial activity, biomass and bacterial ribotype
number than plant species. Liming increased soil pH,
microbial activity and biomass, while decreasing
ribotype number. Nitrogen addition decreased soil
pH, microbial activity and ribotype number. Addition
of lime plus nitrogen had intermediate effects, which
appeared to be driven more by lime than nitrogen.
Terminal restriction fragment length polymorphism
(TRFLP) analysis revealed that lime and nitrogen
addition altered soil bacterial community structure,
while plant species had little effect. These results
were further confirmed by multivariate redundancy
analysis, and suggest that soil lime and nitrogen status
are more important controllers of bacterial community
structure than plant rhizosphere effects
Effect of fibre length and chemical modifications on the tensile properties of intimately mixed short sisal/glass hybrid fibre reinforced low density polyethylene composites
Get PDFAbstract: Hybrid composites prepared by the incorporation of two or more different types of fibres into a single polymer matrix deserve much attention. This method of hybridisation of composites offers a profitable procedure for the fabrication of products while the resulting materials are noted for their high specific strength, modulus and thermal stability. The influence of the relative composition of short sisal/glass fibres, their length and distribution on the tensile properties of short sisal/glass intimatelymixed polyethylene composites (SGRP) was examined. Different compositions of sisal and glass such as 70/30, 50/50 and 30/70 have been prepared with varying fibre lengths in the range of 1–10mm. Emphasis has also been given to the variation of fibre–matrix adhesion with several fibre chemical modifications. Chemical surface modifications such as alkali, acetic anhydride, stearic acid, permanganate, maleic anhydride, silane and peroxides given to the fibres and matrix were found to be successful in improving the interfacial adhesion and compatibility between the fibre and matrix. The nature and extent of chemicalmodifications were analysed by infrared spectroscopy while improvement in fibre–matrix adhesion was checked by studying the fractography of composite samples using a scanning electron microscope. Assessment of water retention values has been found to be a successful tool to characterize the surface of the stearic acid modified fibres. It was found that the extent of improvement in tensile properties of SGRP varied with respect to the nature of chemical modifications between fibre and matrix. Improved mechanical anchoring and physical and chemical bonding between fibre and polyethylene matrix are supposed to be the reasons for superior tensile strength and Young’s modulus in treated composites. Several secondary reasons such as high degree of fibre dispersion and reduced hydrophilicity in chemically modified fibres also are believed to play a role. Among the various chemical modifications, the best tensile strength and modulus was exhibited by the SGRP with benzoyl peroxide treated fibres. This is attributed to the peroxide-initiated grafting of polyethylene on to the fibres. 2004 Society of Chemical Industr
Overhead Issues for Local Access Points in IPSec enabled VPNs
Get PDFVirtual Private Networks (VPNs) use the Internet or other network service as a backbone to provide a secure connection across a potentially hostile WAN. Such security guarantees provide the motivation for VPN deployment. This security does, however, come at a performance cost brought about by the increased processing overhead. This paper presents an investigation into these overheads. In particular, this investigation will consider the server side overhead for VPN deployments and seek to establish a relationship between this overhead and the number of clients being serviced
'TEAMWORK': A COMBINED METHODOLOGICAL AND TECHNOLOGICAL SOLUTION FOR E-WORKING ENVIRONMENTS
Get PDFThe word 'virtual' describes work that spans one or more discontinuities. The term has been applied to work where people are in discontinuous physical work locations, where work is done in discontinuous time frames, where people have discontinuous organizational affiliations (Watson-Manheim, Crowston & Chudoba (2002)).
Community is an important aspect of life for most people. Cooley (1983) states that all normal humans have a natural affinity for community. He suggests that the primary factor inhibiting the formation of communities, no matter what their scale, is that they are difficult to organise. Extending the moral ideas inherent in nearly all individuals to the notion of community requires a system or institutional framework. The development and maintenance of such institutions sap the energy of the members of the would-be community and confuse the moral ideals inherent in the notion of community with the project of the institution itself (Fernback & Thompson (1995)). Given the development of new communications technologies we need to continuously examine the new relations and their potential for new or renewed relationships that arise in this context. Alongside these developments researchers have been advocating the need for a fundamental revision of software technology support in organisations for some time (Wood & Wood-Harper (1993)). However, few have proposed a basis upon which this progress can be made. This paper argues that new technological forms must recognise that organisational members act in fluid ways and, that organisations are moving towards flexible forms in virtual space. It thus attempts to address this gap in the academic literature, as well as in common practice. The paradigm proposed here is based upon a model of IT, which views organisations in terms of roles operating in particular settings or 'scenarios'. The remainder of this paper briefly reviews a new solution based upon this role-scenario paradigm. ..
Fingerprinting the fungal community
Get PDFFungi can be found in almost any environment, and play important roles in ecosystem processes such as nutrient
cycling and degradation. Despite their importance, the vast majority of fungi have not yet been isolated and identified.
Due to the difficulties inherent in culture-based methods, fungal ecologists have turned to community fingerprinting
techniques, which utilise signal molecules to profile the fungal members of an environmental sample
without culturing. Commonly used signal molecules include chitin, ergosterol, membrane lipids, and nucleic acids.
Several DNA-based fingerprinting methods have been successfully applied to fungal communities, including
D/TGGE (denaturing/temperature gradient gel electrophoresis), SSCP (single-stranded conformational polymorphism),
RISA (ribosomal intergenic spacer analysis), and T-RFLP (terminal restriction length fragment polymorphism).
These techniques allow the fungal ecologist to rapidly profile fungal populations in an ecosystem, without
the need for laborious culturing or cloning
A Reflection of the Development, Activities and Deliverables of the Construction IT Alliance (CITA) In Ireland
Get PDFThis paper reflects on the development, activities and deliverables of the Construction IT Alliance in the Republic of Ireland. This alliance was formed in 2001 with the vision of harnessing the potential of information and communication technologies in the Irish construction sector. CITA is a prime example of academia-industry-government collaboration in Ireland. A key driver in the development of CITA is the need to increase the extent of IT knowledge within the Irish construction sector. Membership of CITA includes leading architectural, engineering, surveying, management, construction, supplier, IT and academic organisations.
The leading academic institutions in CITA are the Dublin Institute of Technology (DIT) and the Waterford Institute of Technology (WIT). CITA has also received the backing of the Department of the Environment and Local Government (DoE&LG) and the influential Forum for the Construction Industry (FCI).
The structure and work of other similar bodies, particularly Construct IT in the UK, were taken into account in the development of CITA. CITA activities include the development and maintenance of a website; the hosting of bi-annual members meetings with expert guest speakers; and the formation and encouragement of Special Interest Groups (SIGs) to address particular issues
Adaptive Measurement-based QoS Management in DiffServ Networks for Variable Bit Rate Applications
No full textIn per-flow based resource reservation techniques, bandwidth allocation for Variable Bit Rate (VBR) applications through real time flow measurements is limited. This limitation is due mainly to scalability problems. In aggregated traffic flow networks such as Differentiated Services (DiffServ), measurement-based bandwidth allocation leads to optimisation of network resources as it links resource allocation to actual usage. With Constant Bit Rate (CBR) applications, simple summation of pre-specified bandwidths is a sufficient solution for resource optimisation in DiffServ networks. However, the pre-specified bandwidth technique is an inefficient approach to DiffServ bandwidth allocation for VBR applications. These applications are generally unaware in advance of their specific bandwidth requirements. This paper describes an adaptive Quality of Service (QoS) management technique that provides an efficient resource allocation scheme for VBR applications in aggregate traffic flows. This method is, in effect, a measurement-based and linearly predicted bandwidth allocation scheme
Fingerprinting the fungal community
No full textFungi can be found in almost any environment, and play important roles in ecosystem processes such as nutrient cycling and degradation. Despite their importance, the vast majority of fungi have not yet been isolated and identified. Due to the difficulties inherent in culture-based methods, fungal ecologists have turned to community fingerprinting techniques, which utilise signal molecules to profile the fungal members of an environmental sample without culturing. Commonly used signal molecules include chitin, ergosterol, membrane lipids, and nucleic acids. Several DNA-based fingerprinting methods have been successfully applied to fungal communities, including D/TGGE (denaturing/temperature gradient gel electrophoresis), SSCP (single-stranded conformational polymorphism), RISA (ribosomal intergenic spacer analysis), and T-RFLP (terminal restriction length fragment polymorphism). These techniques allow the fungal ecologist to rapidly profile fungal populations in an ecosystem, without the need for laborious culturing or cloning
Promoting eWork in Remote Regions: Lessons from FlexWork
No full textThe FlexWork project provided a set of knowledge objects (handbook, templates, cases, decision support tools) to business advisors in ten European regions and assisted them in learning about flexible working. These advisors were also provided with standardised presentation materials and supported in deploying knowledge about flexible working to their constituencies of SME clients at regional level (multiplier). The demand for knowledge about flexible working among business advisors and their clients was seen to be significant, and uptake was supported by evidence of usage of online materials. The experience supported refinement of the package of materials, and provided several lessons of benefit to future initiatives supporting regional information society uptake. http://www.flexwork.eu.co