1,722,091 research outputs found
Three-dimensional model and characterization of the iron stress-induced CP43'-photosystem I supercomplex isolated from the cyanobacterium Synechocystis PCC 6803.
No full textThe cyanobacterium Synechocystis PCC 6803 has been subjected to growth under iron-deficient conditions. As a consequence, the isiA gene is expressed, and its product, the chlorophyll a-binding protein CP43', accumulates in the cell. Recently, we have shown for the first time that 18 copies of this photosystem II (PSII)-like chlorophyll a-binding protein forms a ring around the trimeric photosystem I (PSI) reaction center (Bibby, T. S., Nield, J., and Barber, J. (2001) Nature, 412, 743-745). Here we further characterize the biochemical and structural properties of this novel CP43'-PSI supercomplex confirming that it is a functional unit of approximately 1900 kDa where the antenna size of PSI is increased by 70% or more. Using electron microscopy and single particle analysis, we have constructed a preliminary three-dimensional model of the CP43'-PSI supercomplex and used it as a framework to incorporate higher resolution structures of PSI and CP43 recently derived from x-ray crystallography. Not only does this work emphasize the flexibility of cyanobacterial light-harvesting systems in response to the lowering of phycobilisome and PSI levels under iron-deficient conditions, but it also has implications for understanding the organization of the related chlorophyll a/b-binding Pcb proteins of oxychlorobacteria, formerly known as prochlorophytes
Barber, J R, 310358
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/370051Surname: BARBER
Given Name(s) or Initials: J R
Military Service Number or Last Known Location: 310358
Missing, Wounded and Prisoner of War Enquiry Card Index Number: SEA-3624180311
Item: [2016.0049.02378] "Barber, J R, 310358
Barber, J A, VX41564
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/370077Surname: BARBER
Given Name(s) or Initials: J A
Military Service Number or Last Known Location: VX41564
Missing, Wounded and Prisoner of War Enquiry Card Index Number: 45336180337
Item: [2016.0049.02404] "Barber, J A, VX41564
Barber, J E, VX2146
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/370075Surname: BARBER
Given Name(s) or Initials: J E
Military Service Number or Last Known Location: VX2146
Missing, Wounded and Prisoner of War Enquiry Card Index Number: 1149180335
Item: [2016.0049.02402] "Barber, J E, VX2146
Dr. Vickers sending a message using the communications apparatus in an aeroplane of the Flying Doctor Service, ca. 1932 [transparency] /
No full textTitle devised by cataloguer based on accompanying documentation.; Part of the Australian Inland Mission collection.; Condition: Scrached.; Attribution uncertain.; Also available in an electronic version via the Internet at: http://nla.gov.au/nla.pic-an24669476
Influence of longitudinal creepage and wheel inertia on short-pitch corrugation: a resonance-free mechanism to explain the roaring rail phenomenon
No full textShort-pitch corrugation (30-80 mm in wavelength) in railways, despite being well known since the early days of the railways because of its criticality in producing damage, 'roaring rail' or 'howling wheel' noise, and indirectly rolling contact fatigue, is considered an enigmatic phenomenon. In fact, most available data seem to show a non-linearly increasing wavelength with speed, and an almost fixed wavelength, while most models based on system resonances predict a fixed frequency. More enigmatic still, many data points fall in a range of frequencies where there is no evident resonance in the wheel-railtrack system (the large gap between the low frequencies resonances from 50 to 300 Hz and the very high pinned-pinned mode resonant frequencies which correspond generally to 850-1100 Hz in railways. Yet the most common classifications of corrugation continue to associate corrugation to frequency-fixing mechanisms. Johnson's early studies on the Hertz normal spring resonance suggest that plasticity-based repeats impact mechanism, or differential wear mechanism both seemed to be not appropriate to explain short-pitch corrugation. In particular, longitudinal creepage (obviously associated with braking or acceleration very common on uphill grades, near stations, but also in curves where profiles provide insufficient steering capability) seemed to act to suppress corrugation, rather than promoting it, as suggested in the model of Grassie and Johnson. Only a few, very comprehensive models that include all the relevant receptances consider the effect of wheel inertia: indeed, these models indicate many possible corrugation regimes and, in particular, point at lateral creepage mechanisms at the pinned-pinned resonant frequency as giving much larger growth than longitudinal creepage, so the possibility of a corrugation regime independent of wheelset or railtrack resonances has largely remained hidden, despite it being present in some results. In this paper, a simple model that returns to a pure longitudinal creepage mechanism is suggested, showing that it is essential to include the rotational dynamics of the wheel in the system, similar to Grassie and Johnson's model. In particular, a simple full-stick Winkler-contact mechanics model can estimate the effect of transient contact mechanics. For typical inertias, the conditions are closer to the constant tangential load (which is the correct limit at zero speed anyway) and seem to explain the basic features of wear-induced instability in the existing experimental data. For larger inertias, which may also be possible for heavy wheelsets, the model predicts results closer to Grassie and Johnson's assumption of constant creepage, i.e. only a limited range of possible short-pitch corrugation. The model also suggests that although the growth of corrugation depends strongly on the amplification of the normal load, the wavelength of this mode of corrugation depends very little on the vertical resonances of the systems, so that it would persist even in a model with no resonance altogether. It is possible that the exact frequency of this regime depends on the details of the contact geometry, here simplified using the Winkler model. Finally, a reason why this mechanism of longitudinal creepage corrugation, despite perhaps giving 10-20 times apparently lower growth than lateral creepage, may indeed be the correct mechanism to interpret the classical data, is that longitudinal creepage can be 10 times higher than lateral (5 per cent instead of 0.5 per cent), and as corrugation growth is proportional to square of creepage, there is a factor 100 that largely compensates for this. There is still some progress to be made to obtain a reliable model to compare the various regimes, but clearly this regime should be considered when devising remedies to corrugation
Two unidentified nursing sisters standing on the verandah of the Port Hedland hospital with a dog in the foreground [picture] : taken on a survey trip undertaken in 1927 by Rev. J.A. Barber and Dr. George Simpson for the Flying Doctor Scheme, Western Australia, 1927 ./
No full textTitle devised by cataloguer based on accompanying documentation.; Part of the Australian Inland Mission collection.; Attribution is uncertain.; Condition: Good.; Also available in an electronic version via the Internet at: http://nla.gov.au/nla.pic-an24696998
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