XTH acts at the microfibril-matrix interface during cell elongation

Sulphorhodamine-labelled oligosaccharides of xyloglucan are incorporated into the cell wall of Arabidopsis and tobacco roots, and of cultured Nicotiana tabacum cells by the transglucosylase (XET) action of XTHs. In the cell wall of diffusely growing cells, the subcellular pattern of XET action revealed a 'fibrillar' pattern, different from the xyloglucan localization. The fibrillar fluorescence pattern had no net orientation in spherical cultured cells. It changed to transverse to the long axis when the cells started to elongate, a feature mirroring the rearrangements of cortical microtubules and the accompanying cellulose deposition. Interference with the polymerization of microtubules and with cellulose deposition inhibited this strong and 'fibrillar'-organized XET-action, whereas interference with actin-polymerization only decreased the intensity of enzyme action. Epidermal cells of a mutant with reduced cellulose synthesis also had low XET action. Root hairs (tip-growing cells) exhibited high XET-action over all their length, but lacked the specific parallel pattern. In both diffuse- and tip-growing cell types extraction of the incorporated fluorescent xyloglucans by a xyloglucan-specific endoglucanase reduced the fluorescence, but the 'fibrillar' appearance in diffuse growing cells was not eliminated. These results show that XTHs act on the xyloglucans attached to cellulose microfibrils. After incorporation of the fluorescent oligosaccharides, the xyloglucans decorate the cellulose microfibrils and become inaccessible to hydrolytic enzymes

Role of OH-stretch/torsion coupling and quantum yield effects in the first OH overtone spectrum of cis-cis HOONO

A joint theoretical and experimental investigation is undertaken to study the effects of OH-stretch/HOON torsion coupling and of quantum yield on the previously reported first overtone action spectrum of cis-cis HOONO (peroxynitrous acid). The minimum energy path along the HOON dihedral angle is computed at the coupled cluster singles and doubles with perturbative triples level with correlation consistent polarized quadruple zeta basis set, at the structure optimized using the triple zeta basis set (CCSD(T)/cc-pVQZ//CCSD(T)/cc-pVTZ). The two-dimensional ab initio potential energy and dipole moment surfaces for cis-cis HOONO are calculated as functions of the HOON torsion and OH bond length about the minimum energy path at the CCSD(T)/cc-pVTZ and QCISD/AUG-cc-pVTZ (QCISD—quadratic configuration interaction with single and double excitation and AUG-augmented with diffuse functions) level of theory/basis, respectively. The OH-stretch vibration depends strongly on the torsional angle, and the torsional potential possesses a broad shelf at ~90°, the cis-perp conformation. The calculated electronic energies and dipoles are fit to simple functional forms and absorption spectra in the region of the OH fundamental and first overtone are calculated from these surfaces. While the experimental and calculated spectra of the OH fundamental band are in good agreement, significant differences in the intensity patterns are observed between the calculated absorption spectrum and the measured action spectrum in the 2nuOH region. These differences are attributed to the fact that several of the experimentally accessible states do not have sufficient energy to dissociate to OH+NO2 and therefore are not detectable in an action spectrum. Scaling of the intensities of transitions to these states, assuming D0=82.0 kJ/mol, is shown to produce a spectrum that is in good agreement with the measured action spectrum. Based on this agreement, we assign two of the features in the spectrum to Delta n=0 transitions (where n is the HOON torsion quantum number) that are blue shifted relative to the origin band, while the large peak near 7000 cm^–1 is assigned to a series of Delta n=+1 transitions, with predominant contributions from torsionally excited states with substantial cis-perp character. The direct absorption spectrum of cis-cis HOONO (6300–6850 cm^–1) is recorded by cavity ringdown spectroscopy in a discharge flow cell. A single band of HOONO is observed at 6370 cm^–1 and is assigned as the origin of the first OH overtone of cis-cis HOONO. These results imply that the origin band is suppressed by over an order of magnitude in the action spectrum, due to a reduced quantum yield. The striking differences between absorption and action spectra are correctly predicted by the calculations

Large-scale structure and the redshift-distance relation

In efforts to demonstrate the linear Hubble law v = Hr from galaxy observations, the underlying simplicity is often obscured by complexities arising from magnitude-limited data. In this paper we point out a simple but previously unremarked fact: that the shapes and orientations of structures in redshift space contain in themselves independent information about the cosmological redshift-distance relation. The orientations of voids in the CfA slice support the Hubble law, giving a redshift-distance power index p = 0.83 +/- 0.36 (void data from Slezak, de Lapparent, & Bijoui 1993) or p = 0.99 +/- 0.38 (void data from Malik & Subramanian 1997).Comment: 11 pages (AASTeX), 4 figures, to appear in the Astrophysical Journal Letter

A Review of Propulsion Industrial Base Studies and an Introduction to the National Institute of Rocket Propulsion Systems

Over the past decade there have been over 40 studies that have examined the state of the industrial base and infrastructure that supports propulsion systems development in the United States. This paper offers a comprehensive, systematic review of these studies and develops conclusions and recommendations in the areas of budget, policy, sustainment, infrastructure, workforce retention and development and mission/vision and policy. The National Institute for Rocket Propulsion System (NIRPS) is a coordinated, national organization that is responding to the key issues highlighted in these studies. The paper outlines the case for NIRPS and the specific actions that the Institute is taking to address these issues

QED in strong, finite-flux magnetic fields

Lower bounds are placed on the fermionic determinants of Euclidean quantum electrodynamics in two and four dimensions in the presence of a smooth, finite-flux, static, unidirectional magnetic field $B(r) =(0,0,B(r))$, where $B(r) \geq 0$ or $B(r) \leq 0$, and $r$ is a point in the xy-plane.Comment: 10 pages, postscript (in uuencoded compressed tar file

Researching telecare: the importance of context

Purpose The purpose of this paper is to present a research method which offers insights into the factors which affect the optimal use and implementation of telecare, or which may lead to its rejection by older people with support needs – factors pertinent to those involved in the design and delivery of both telecare research studies and of services. Design/methodology/approach The methodology outlined, influenced by Chicago School and Science and Technology Studies, emphasises the importance of context when examining social phenomena, such as the use of technology. The multi-method approach identified key patterns which provide insights into how telecare was used by a sample of older adults, including information on its suboptimal use and rejection. Findings The study of telecare use in real-life situations – and the investigation of other complex social interventions – requires an approach which fully considers the importance of context in explaining social phenomena. The main value of the method and findings lies in the insights offered to designers of larger studies which seek to generalise results, including telecare randomised control trials, as well as for those involved in the delivery of telecare services to achieve optimal adoption and use. Originality/value The study methods described combined ethnographic, longitudinal and qualitative methodologies and creative research tools in an innovative way to allow exploration of how context affects the uptake and use of telecare

Communication Networks and the adoption of three farn practices

The report commences with a discussion of the diffusion and adoption model, and illustrates some of the research observations and practical outcomes that have emerged in recent years, An overview of social network research is presented as a means of understanding communication exchanges and providing data relevant to the diffusion debate. The communication and adoption studies are then reported in three separate sections in the order they were conducted. (A map of the location of the survey areas is shown in Figure I ) . The objectives, survey method, results and a summary are presented for each study. A background to the dairy herd recording scheme is followed by an outline of the dairy industry itself. Two regions selected for the survey are discussed and compared. The soil conservation study commences with an overview of soil degradation problems, government involvement and policy, and technical solutions to these problems. Consideration is also given to the importance of the human element in soil conservation policy and extension. The Central Wheatbelt (pattern of settlement, landscape, soils, vegetation, climate and land use) is described as a region. Many soil conservation problems exist here that can be generalized to other regions. The minimum tillage enquiry first introduces the concept and technique of minimum tillage, its advantages and disadvantages. A history of the Jerramungup district, as well as details on physical aspects of the area and land use problems gives the setting of the study. Jerramungup (and the south coast region generally) is particularly prone to wind erosion and hence is valid area in which to study the diffusion of minimum tillage a technique which lessens wind erosion problems. A final discussion compares conclusions of each study. in each are are dealt with. the three adoption situations by examining the The extension situation and communication factors Conclusions and recommendations are provided

Farmers\u27 use of agricultural information 1983

The Western Australian Department of Agriculture produces information for farmers which is disseminated through various mass media, The Australian Broadcasting Commission and commercial media outlets provide further agricultural information, In 1983 a telephone survey of cereal-sheep farmers was undertaken to determine what information sources were used by farmers, and how farmers used that information. A number of information processing factors were taken from communication research literature, These were accessibility and availability; surveillance and exposure; selection; storage and retrieval. From within this theoretical framework, information sources such as farming magazines, radio and television programmes were examined. Special attention was given to evaluating the performance of the following Department of Agriculture media: Farmnotes, Bulletins, Journal of Agriculture, Direct Mail Service, Agricultural Memos, Farming Today and radio broadcasts. There was considerable activity by farmers in surveillance, selection, storing and retrieving of information. It was found that the availability and exposure of Departmental media to farmers was high, except for the Journal of Agriculture, It is recommended that the form and content of the Journal be reviewed, and the circulation of this and other information sources be further increased. Revision of the little used Agdex filing system is also necessary. Other recommendations include: greater recognition of the role of the farm family in information processing, the provision of \u27entertaining\u27 agricultural television programmes for rural communities, and the need for farmer awareness of information storage and retrieval systems. Because the functions of the Direct Mail Service and Agricultural Memos were found to overlap, it is suggested that the use of these information sources could be studied further to test for redundancies in Departmental effort. It is also proposed that the Department should not commit itself to disseminating technical information through audio and video-tapes unless the effectiveness of these media can be demonstrated