903 research outputs found
Regionalism in rural settlement in the Pennines of north-west Yorkshire
In the Pennines of North-West Yorkshire the mainphysical divisions include the major valleys of Wensleydale, Swaledale, Nidderdale, Wharfedale and Ribblesdale, with the Vale of York to the east and the Graven Lowland to the south. Ever since Anglo-Saxon times these regions have been much more intensively farmed and have always supported denser populations and bigger villages. Most outstanding in these respects, apart from the lowlands bordering the Pennines, have always been the wider valleys of Wensleydale (below Hawes), Lower Nidderdale (below Pateley Bridge), Middle Wharfedale (around Grassington) and Lower Wharfedale (below Bolton Abbey).This regionalism in relation to the physical aspects is. seen also in settlement morphology and the extent to which dwellings are nucleated or dispersed. Street villages and those with the square plan are today limited to the lowlands and Major: Valleys, as also are village greens. The Graven Lowland, a great trans-Pennine route, is distinguished by a linear pattern of population distribution and village growth. The Pennine border on the east, where there are few major relief contrasts, is best taken as the edge of the humraocky drift which characterises the Vale of York. This boundary, which to some extent affects soils, finds its reflection very broadly in farming and settlement. The land to the east, often with bigger villages, has more arable cultivation and has had ever since Domesday Survey times. There are further differences here, as in architecture and building materials. The geological or lithological divisions of the Pennines (Craven Highlands, Yoredales Pennines, Millstone Grit Dipslope) are most clearly reflected in settlement in the Prehistoric Period when there was a tendency for the Graven Highlands, with well-drained limestone tracts and open grasslands, to attract the peoples and cultures
The Human Behind the Data: Reflections from an Ongoing Co-Design and Deployment of a Data-Navigation Interface for Front-Line Emergency Housing Shelter Staff
On any night in Canada, at least 35,000 individuals experience homelessness.
These individuals use emergency shelters to transition out of homelessness and
into permanent housing. We designed and deployed a technology to support
front-line staff at the largest emergency housing shelter in Calgary, Canada.
Over a period of five months in 2022, we worked closely with front-line staff
to co-design an interface for supporting a holistic understanding of client
context and facilitating decision-making. The tool is currently in-use and our
collaboration is ongoing. In this paper, we reflect on preliminary findings
regarding the second iteration of the tool. We find that supporting shelter
staff in understanding the human behind the data was a critical component of
design. This work contributes to literature on how data tools may be integrated
into homeless shelters in a way that aligns with shelters' values.Comment: 7 page
PHYCOBILISOMES AND ISOLATED PHYCOBILIPROTEINS. EFFECT OF GLUTARDIALDEHYDE AND BENZOQUINONE ON FLUORESCENCE
The fluorescence of the biliproteins C-phycocyanin from Spirulina platensis, B-phycoerythrin
from Porphyridium cruentum and of isolated whole P. cruentum phycobilisomes is quenched in the
presence of glutardialdehyde (GA) or benzoquinone (BQ). The kinetics of fluorescence decrease thus
induced is biphasic. If GA is used as a quencher, the fluorescence can be recovered at 77 K. Contrary to
the GA-effect, only a minor recovery takes place with BQ at 77K, thus demonstrating a different
mechanism of action of GA and BQ on biliprotein
Electron localisation function in current-density-functional theory
We present a generalisation of the electron localisation function (ELF) to current-density-functional theory as a descriptor for the properties of molecules in the presence of magnetic fields. The resulting current ELF (cELF) is examined for a range of small molecular systems in field strengths up to B0 = 235 kT (one atomic unit). The cELF clearly depicts the compression of the molecular electronic structure in the directions perpendicular to the applied field and exhibits a structure similar to that of the physical current densities. A topological analysis is performed to examine the changes in chemical bonding upon application of a magnetic field
Modulation of type IV collagenase and plasminogen activator in a hamster fibrosarcoma by basement membrane components and lung fibroblasts.
The effect of basement membrane components (laminin, fibronectin and type IV collagen) and lung fibroblasts on type IV collagenase and plasminogen activator activity was investigated in a primary HSV-2-induced hamster fibrosarcoma, and its in vivo derived sublines and in vitro derived clones of varying metastatic potential. Fibronectin and type IV collagen were ineffective at influencing the expression of either type IV collagenase or plasminogen activator activity. Laminin, however, at concentrations of 1-10 micrograms ml-1 added to the serum-free culture supernatants, increased the release of type IV collagenase by up to 100% for the parental cell line. Three highly metastatic sublines (two from in vivo origin and one from in vitro cloning) showed increases of up to 300%. Non-metastatic sublines (two from in vivo origin and one from in vitro cloning), however, showed no increase in type IV collagenase activity. Plasminogen activator release from either the parental line cell or its metastatic sublines and clones, was unaffected by the addition of laminin. Addition of tumour cells to lung fibroblast monolayers resulted in an increased expression of PA activity in the supernatant, whilst type IV collagenase activity was reduced
Non-perturbative calculation of molecular magnetic properties within current-density functional theory
We present a novel implementation of Kohn-Sham density-functional theory utilizing London atomic orbitals as basis functions. External magnetic elds are treated non-perturbatively, which enables the study of both magnetic response properties and the effects of strong fields, using either standard density functionals or current-density functionals - the implementation is the first fully self-consistent implementation of the latter for molecules. Pilot applications are presented for the finite-field calculation of molecular magnetizabilities, hypermagnetizabilities and nuclear magnetic resonance shielding constants, focusing on the impact of current-density functionals on the accuracy of the results. Existing current-density functionals based on the gauge-invariant vorticity are tested and found to be sensitive to numerical details of their implementation. Furthermore, when appropriately regularized, the resulting magnetic properties show no improvement over standard density-functional results. An advantage of the present implementation is the ability to apply density-functional theory to molecules in very strong magnetic fields, where the perturbative approach breaks down. Comparison with high accuracy full-conguration-interaction results shows that the inadequacies of current-density approximations are exacerbated with increasing magnetic field strength. Standard density-functionals remain well behaved but fail to deliver high accuracy. The need for improved current-dependent density-functionals, and how they may be tested using the presented implementation, is discussed in light of our findings
Site-selective spectroscopy and level ordering in C-phycocyanin
We present a combined fluorescence and hole-burning study of the biliprotein C-phycocyanin. Sharp zero-phonon holes compare with a broad structureless fluorescence. This finding is rationalized in terms of the special level structure in this pigment, the fast energy-transfer processes and a lack of correlation of the energies of the emissive states
Current density functional theory using meta-generalized gradient exchange-correlation functionals
We present the self-consistent implementation of current-dependent (hybrid)
meta generalized gradient approximation (mGGA) density functionals using London
atomic orbitals. A previously proposed generalized kinetic energy density is
utilized to implement mGGAs in the framework of Kohn--Sham current
density-functional theory (KS-CDFT). A unique feature of the non-perturbative
implementation of these functionals is the ability to seamlessly explore a wide
range of magnetic fields up to 1 a.u. (T) in strength. CDFT
functionals based on the TPSS and B98 forms are investigated and their
performance is assessed by comparison with accurate CCSD(T) data. In the weak
field regime magnetic properties such as magnetizabilities and NMR shielding
constants show modest but systematic improvements over GGA functionals.
However, in strong field regime the mGGA based forms lead to a significantly
improved description of the recently proposed perpendicular paramagnetic
bonding mechanism, comparing well with CCSD(T) data. In contrast to functionals
based on the vorticity these forms are found to be numerically stable and their
accuracy at high field suggests the extension of mGGAs to CDFT via the
generalized kinetic energy density should provide a useful starting point for
further development of CDFT approximations
FÖRSTER TRANSFER CALCULATIONS BASED ON CRYSTAL STRUCTURE DATA FROM Agmenellum quadruplicatum C-PHYCOCYANIN
Excitation energy transfer in C-phycocyanin is modeled using the Forster inductive resonance mechanism. Detailed calculations are carried out using coordinates and orientations of the chromophores derived from X-ray crystallographic studies of C-phycocyanin from two different species (Schirmer et al, J. Mol. Biol. 184, 257–277 (1985) and ibid., 188, 651-677 (1986)). Spectral overlap integrals are estimated from absorption and fluorescence spectra of C-phycocyanin of Mastigocladus laminosus and its separated subunits. Calculations are carried out for the β-subunit, αβ-monomer, (αβ)3-trimer and (αβ)0-hexamer species with the following chromophore assignments: β155 = 's’(sensitizer), β84 =‘f (fluorescer) and α84 =‘m’(intermediate):]:. The calculations show that excitation transfer relaxation occurs to 3=98% within 200 ps in nearly every case; however, the rates increase as much as 10-fold for the higher aggregates. Comparison with experimental data on fluorescence decay and depolarization kinetics from the literature shows qualitative agreement with these calculations. We conclude that Forster transfer is sufficient to account for all of the observed fluorescence properties of C-phycocyanin in aggregation states up to the hexamer and in the absence of linker polypeptides
THERMAL DENATURATION OF MONOMERIC AND TRIMERIC PHYCOCYANINS STUDIED BY STATIC AND SPECTROSCOPY POLARIZED TIME-RESOLVED FLUORESCENCE
C-Phycocyanin (PC) and allophycocyanin (APC). as well as the a-subunit of PC. have been
isolated from the blue-green alga (cyanobacterium). Spirulina platensis. The effects of partial thermal
denaturation of PC and of its state of aggregation have been studied by ps time-resolved, polarized
fluorescence spectroscopy. All measurements have been performed under low photon fluxes (< 10’ ’
photonsipulse x cm’) to minimize singlet-singlet annihilation processes. A complex decay is obtained
under most conditions, which can be fitted satisfactorily with a bi-exponential (7’ = 70400 ps. T? =
1000-3000 ps) for both the isotropic and the polarized part, but with different intensities and time
constants for the two decay curves. The data are interpreted in the frameworkof the model first developed
by Teak and Dale (Biochern. J. 116, 161 (1970)], which divides the spectroscopically different
chromophores in (predominantly) sensitizing (s) and fluorescing U, ones. If one assumes temperature
dependent losses in the energy transfer from the s to the f and between f chromophores. both the
biexponential nature of the isotropic fluorescence decay and the polarization data can be rationalized. In
the isotropic emission (corresponding to the population of excited states) the short lifetime is related to the
s-,f transfer. the longer one to the “free“ decay of the final acceptor(s) (= f). The polarized part is
dominated by an extremely short decay time. which is related to s+f transfer, as well as to resonance
transfer between the f-chromophores
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