Developing agricultural education in the Republic of Croatia using UK examples

Based on comparisons with the UK and a survey of University level Croatian agricultural students, a model was developed to explore the influence of various factors on successful completion of courses. From a knowledge of significant factors, tutors could predict the probability that new students would be successful and so guide them accordingly. In Croatia, where oral examination methods predominate, many students avoid taking these examinations for several months. It is suggested that three key elements for improving the quality of agricultural studies in Croatia are (i) improving the confidence of the students in conjunction with (ii) a more rigorous, compulsory examination procedure and (iii) a supportive tutorial system.

Cellulose microfibril angle in the cell wall of wood fibres

The term microfibril angle (MFA) in wood science refers to the angle between the direction of the helical windings of cellulose microfibrils in the secondary cell wall of fibres and tracheids and the long axis of cell. Technologically, it is usually applied to the orientation of cellulose microfibrils in the S2 layer that makes up the greatest proportion of the wall thickness, since it is this which most affects the physical properties of wood. This review describes the organisation of the cellulose component of the secondary wall of fibres and tracheids and the various methods that have been used for the measurement of MFA. It considers the variation of MFA within the tree and the biological reason for the large differences found between juvenile (or core) wood and mature (or outer) wood. The ability of the tree to vary MFA in response to environmental stress, particularly in reaction wood, is also described. Differences in MFA have a profound effect on the properties of wood, in particular its stiffness. The large MFA in juvenile wood confers low stiffness and gives the sapling the flexibility it needs to survive high winds without breaking. It also means, however, that timber containing a high proportion of juvenile wood is unsuitable for use as high-grade structural timber. This fact has taken on increasing importance in view of the trend in forestry towards short rotation cropping of fast grown species. These trees at harvest may contain 50% or more of timber with low stiffness and therefore, low economic value. Although they are presently grown mainly for pulp, pressure for increased timber production means that ways will be sought to improve the quality of their timber by reducing juvenile wood MFA. The mechanism by which the orientation of microfibril deposition is controlled is still a matter of debate. However, the application of molecular techniques is likely to enable modification of this process. The extent to which these techniques should be used to improve timber quality by reducing MFA in juvenile wood is, however, uncertain, since care must be taken to avoid compromising the safety of the tree.

Reversible phase variation in the phnE gene, which is required for phosphonate metabolism in Escherichia coli K-12

It is known that Escherichia coli K-12 is cryptic (Phn(-)) for utilization of methyl phosphonate (MePn) and that Phn(+) variants can be selected for growth on MePn as the sole P source. Variants arise from deletion via a possible slip strand mechanism of one of three direct 8-bp repeat sequences in phnE, which restores function to a component of a putative ABC type transporter. Here we show that Phn(+) variants are present at the surprisingly high frequency of >10(-2) in K-12 strains. Amplified-fragment length polymorphism analysis was used to monitor instability in phnE in various strains growing under different conditions. This revealed that, once selection for growth on MePn is removed, Phn(+) revertants reappear and accumulate at high levels through reinsertion of the 8-bp repeat element sequence. It appears that, in K-12, phnE contains a high-frequency reversible gene switch, producing phase variation which either allows ("on" form) or blocks ("off" form) MePn utilization. The switch can also block usage of other metabolizable alkyl phosphonates, including the naturally occurring 2-aminoethylphosphonate. All K-12 strains, obtained from collections, appear in the "off" form even when bearing mutations in mutS, mutD, or dnaQ which are known to enhance slip strand events between repetitive sequences. The ability to inactivate the phnE gene appears to be unique to K-12 strains since the B strain is naturally Phn(+) and lacks the inactivating 8-bp insertion in phnE, as do important pathogenic strains for which genome sequences are known and also strains isolated recently from environmental sources.

Role of Nrf2 in the regulation of CD36 and stress protein expression in murine macrophages - Activation by oxidatively modified LDL and 4-hydroxynonenal

CD36 is an important scavenger receptor mediating uptake of oxidized low- density lipoproteins ( oxLDLs) and plays a key role in foam cell formation and the pathogenesis of atherosclerosis. We report the first evidence that the transcription factor Nrf2 is expressed in vascular smooth muscle cells, and demonstrate that oxLDLs cause nuclear accumulation of Nrf2 in murine macrophages, resulting in the activation of genes encoding CD36 and the stress proteins A170, heme oxygenase- 1 ( HO- 1), and peroxiredoxin I ( Prx I). 4- Hydroxy- 2- nonenal ( HNE), derived from lipid peroxidation, was one of the most effective activators of Nrf2. Using Nrf2- deficient macrophages, we established that Nrf2 partially regulates CD36 expression in response to oxLDLs, HNE, or the electrophilic agent diethylmaleate. In murine aortic smooth muscle cells, expressing negligible levels of CD36, both moderately and highly oxidized LDL caused only limited Nrf2 translocation and negligible increases in A170, HO- 1, and Prx I expression. However, treatment of smooth muscle cells with HNE significantly enhanced nuclear accumulation of Nrf2 and increased A170, HO- 1, and Prx I protein levels. Because PPAR-gamma can be activated by oxLDLs and controls expression of CD36 in macrophages, our results implicate Nrf2 as a second important transcription factor involved in the induction of the scavenger receptor CD36 and antioxidant stress genes in atherosclerosis.

Crops and cultures in the Pacific: new data and new techniques for the investigation of old questions

Fifty years ago Carl Sauer suggested, controversially and on the basis of theory rather than evidence, that Southeast Asia was the source area for agriculture throughout the Old World, including the Pacific. Since then, the archaeobotanical record (macroscopic and microscopic) from the Pacific islands has increased, leading to suggestions, also still controversial, that Melanesia was a center of origin of agriculture independent of South-east Asia, based on tree fruits and nuts and vegetatively propagated starchy staples. Such crops generally lack morphological markers of domestication, so exploitation, cultivation and domestication cannot easily be distinguished in the archaeological record. Molecular studies involving techniques such as chromosome painting, DNA fingerprinting and DNA sequencing, can potentially complement the archaeological record by suggesting where species which were spread through the Pacific by man originated and by what routes they attained their present distributions. A combination of archaeobotanical and molecular studies should therefore eventually enable the rival claims of Melanesia versus South-east Asia as independent centers of invention of agriculture to be assessed.

Distribution of nutrients in the root zone affects yield, quality and blossom end rot of tomato fruits

Tomato plants (Lycopersicon esculentum Mill. 'DRK') were grown hydroponically in two experiments to determine the effects of nutrient concentration and distribution in the root zone on yield, quality and blossom end rot (BER). The plants were grown in rockwool with their root systems divided into two portions. Each portion was irrigated with nutrient solutions with either the same or different electrical conductivity (EC) in the range 0 to 6 dS m(-1). In both experiments, fruit yields decreased as EC increased from moderate to high when solutions of equal concentration were applied to both portions of the root system. However, higher yields were obtained when a solution with high EC was applied to one portion of the root system and a solution of low EC to the other portion. For example, the fresh weight of mature fruits in the 6/6 treatment was only 20% that of the 3/3 treatment but the 6/0 treatment had a yield that was 40% higher. The reduction in yield in the high EC treatments was due to an increase in the number of fruits with BER and smaller fruit size. BER increased from 12% to 88% of total fruits as EC increased from 6/0 to 6/6 and fruit length decreased from 67 mm to 52 mm. Fruit quality (expressed as titratable acidity and soluble solids) increased as EC increased. In summary, high yields of high quality tomatoes with minimal incidence of BER were obtained when one portion of the root system was supplied with a solution of high EC and the other portion with a solution of moderate or zero EC.

A new motif in the formation of peptide nanotubes: the crystallographic signature

Terminally protected acyclic tripeptides Boc-Tyr(1)-Val(2)-Tyr(3)-OMe 1 and Boc-Tyr(1)-lle(2)-Tyr(3)-OMe 2 self-assemble into nanotubes in crystals through various noncovalent interactions with an average internal diameter of 5 Angstrom (0.5 nm), and the tubular ensemble is developed through the hydrogen-bonded side chains of tyrosine residues. The inside of the hollow nanotubular structures is hydrophilic; however, no solvent molecules have been crystallographically detected.

Sustainable refurbishment: quantifying the impact of façade changes in multi-storey, multi-occupancy buildings

Building refurbishment is key to reducing the carbon footprint and improving comfort in the built environment. However, quantifying the real benefit of a facade change, which can bring advantages to owners (value), occupants (comfort) and the society (sustainability), is not a simple task. At a building physics level, the changes in kWh per m2 of heating / cooling load can be readily quantified. However, there are many subtle layers of operation and mainte-nance below these headline figures which determine how sustainable a building is in reality, such as for example quality of life factors. This paper considers the range of approached taken by a fa/e refurbishment consortium to assess refurbishment solutions for multi-storey, multi-occupancy buildings and how to critically evaluate them. Each of the applued tools spans one or more of the three building parameters of people, product and process. 'De-cision making' analytical network process and parametric building analysis tools are described and their potential impact on the building refurbishment process evaluated.

Cellulose microfibril angle in the cell wall of wood fibres

The term microfibril angle (MFA) in wood science refers to the angle between the direction of the helical windings of cellulose microfibrils in the secondary cell wall of fibres and tracheids and the long axis of cell. Technologically, it is usually applied to the orientation of cellulose microfibrils in the S2 layer that makes up the greatest proportion of the wall thickness, since it is this which most affects the physical properties of wood. This review describes the organisation of the cellulose component of the secondary wall of fibres and tracheids and the various methods that have been used for the measurement of MFA. It considers the variation of MFA within the tree and the biological reason for the large differences found between juvenile (or core) wood and mature (or outer) wood. The ability of the tree to vary MFA in response to environmental stress, particularly in reaction wood, is also described. Differences in MFA have a profound effect on the properties of wood, in particular its stiffness. The large MFA in juvenile wood confers low stiffness and gives the sapling the flexibility it needs to survive high winds without breaking. It also means, however, that timber containing a high proportion of juvenile wood is unsuitable for use as high-grade structural timber. This fact has taken on increasing importance in view of the trend in forestry towards short rotation cropping of fast grown species. These trees at harvest may contain 50% or more of timber with low stiffness and therefore, low economic value. Although they are presently grown mainly for pulp, pressure for increased timber production means that ways will be sought to improve the quality of their timber by reducing juvenile wood MFA. The mechanism by which the orientation of microfibril deposition is controlled is still a matter of debate. However, the application of molecular techniques is likely to enable modification of this process. The extent to which these techniques should be used to improve timber quality by reducing MFA in juvenile wood is, however, uncertain, since care must be taken to avoid compromising the safety of the tree.

Innovation care pathways and the healthcare built environment: An explanatory framework and research agenda

The built environment in which health and social care is delivered can have an impact on the efficiency and outcomes of care processes. The health-care estate is large and growing and is expensive to build, adapt and maintain. The design of these buildings is a complex, difficult and political process. Better use of care pathways as an input to the design and use of the built environment has the potential to deliver significant benefits. A number of variations on the idea of care pathways are already used in designing health-care buildings but this is under-researched. This paper provides a framework for thinking about care pathways and the health-care built environment. The framework distinguishes between five different pathway ‘types’ defined for the purpose of understanding the relationship between pathways and infrastructure. The five types are: ‘care pathways’, ‘integrated care pathways’, ‘patient pathways’, ‘patient journeys’ and ‘patient flows’. The built environment implications of each type are discussed and recommendations made for those involved in either building development or care pathway projects.

Forum theorizing in the context of professional practice: The case for middle-range theories

This commentary seeks to complement the contribution of the Building Research & Information special issue on 'Developing Theories for the Built Environment' (2008) by highlighting the important role of middle-range theories within the context of professional practice. Middle-range theories provide a form of theorizing that lies between abstract grand theorizing and atheoretical local descriptions. They are also characterized by the way in which they directly engage with the concerns of practitioners. In the context of professional practice, any commitment to theorizing should habitually be combined with an equivalent commitment to empirical research; rarely is it appropriate to neglect one in favour of the other. Any understanding of the role that theory plays in professional practice must further be informed by Schon's seminal ideas on reflective practice. Practitioners are seen to utilize theories as inputs to a process of continuous reflection, thereby guarding against complacency and routinization. The authors would challenge any assumption that academics alone are responsible for generating theories, thereby limiting the role of practitioners to their application. Such a dichotomized view is contrary to established ideas on Mode 2 knowledge production and current trends towards co-production research in the context of the built environment.

Risk under performance-based contracting in the UK construction sector

As a method of procuring the services of the built environment, performance-based contracting (PBC) seeks to link the building supplier to longer term commitments than has traditionally been the case in the construction sector. By rewarding the building producer according to the way that building or structure delivers the users' requirements, rather than according to a list of assembled parts, a number of additional risks are taken by contractors, including fitness for purpose, costs and briefing. The extent to which contractors recognize these risks and their methods of dealing with them vary considerably and are influenced by their attitudes towards risk. As the risks associated with PBC are seen as large, uninsurable, and vulnerable to changing client requirements, the majority of respondents would reject the use of PBC as a method of contracting. Nevertheless, PBC may be used under particular conditions, where rewards are deemed sufficient to compensate for the additional risk to the contractor of undertaking work on the basis of a stream of payments paid over the life of a structure depending on the satisfactory performance of the building or as part of a private finance initiative.

The symbiotic roles of empirical experimentation and thought experimentation in the learning of physics

This study was an attempt to identify the epistemological roots of knowledge when students carry out hands-on experiments in physics. We found that, within the context of designing a solution to a stated problem, subjects constructed and ran thought experiments intertwined within the processes of conducting physical experiments. We show that the process of alternating between these two modes- empirically experimenting and experimenting in thought- leads towards a convergence on scientifically acceptable concepts. We call this process mutual projection. In the process of mutual projection, external representations were generated. Objects in the physical environment were represented in an imaginary world and these representations were associated with processes in the physical world. It is through this coupling that constituents of both the imaginary world and the physical world gain meaning. We further show that the external representations are rooted in sensory interaction and constitute a semi-symbolic pictorial communication system, a sort of primitive 'language', which is developed as the practical work continues. The constituents of this pictorial communication system are used in the thought experiments taking place in association with the empirical experimentation. The results of this study provide a model of physics learning during hands-on experimentation.