720 research outputs found
Development and application of operational techniques for the inventory and monitoring of resources and uses for the Texas coastal zone
The author has identified the following significant results. Four LANDSAT scenes were analyzed for the Harbor Island area test sites to produce land cover and land use maps using both image interpretation and computer-assisted techniques. When evaluated against aerial photography, the mean accuracy for three scenes was 84% for the image interpretation product and 62% for the computer-assisted classification maps. Analysis of the fourth scene was not completed using the image interpretation technique, because of poor quality, false color composite, but was available from the computer technique. Preliminary results indicate that these LANDSAT products can be applied to a variety of planning and management activities in the Texas coastal zone
Cognitive Differences Between Congenitally and Adventitiously Blind Individuals.
It is apparent from the historical perspective regarding the theories of cognitive development and the cognitive functioning of individuals with visual impairments, that sight plays a major role in the development of certain cognitive processes. However, the affects of visual impairment on cognitive development remain to be at issue. Since sight seems to be highly integral in cognitive development beginning in the early stages of physical development, about the sixth month of life, and then begins to diminish in importance as verbal communication develops around eighteen months, then it should stand to reason that significant visual impairment or blindness occurring prior to this time would adversely impact an individual's cognitive development. Conversely, the occurrence of visual impairment or blindness after this critical period of development would have less of an impact. Cognitive theorists have proposed that visually impaired or blind persons may have developed different cognitive pathways to acquire, process, and accommodate sensory information. As a result, visually impaired or blind (VI/B) persons may "think differently" than sighted individuals. The present study was designed to address these issues as they relate to cognitive and neuropsychological development at various stages of growth and to examine possible differences in neuropsychological functioning dependent on the level of visual functioning a person retains; e.g. both the issues of age at onset and degree of impairment. It was also designed to study the possible interaction effects of degree of impairment with the age of onset. Findings indicated that the only differences in cognitive functioning appear to be related to age of onset and not the level of visual impairment. The findings further suggested that congenitally blind individuals have indeed developed alternate methods of cognitively processing nonverbal, abstract, or complex information, especially information involving a high degree of spatial orientation. Implications of this study may influence the educational methods used to teach congenitally blind individuals in order to reinforce these alternate pathways and facilitate more effective means of negotiating in a sighted environment
NADPH as a potential intrinsic probe for tumour margin estimation
The fluorescent properties of the reduced coenzyme NADH and its phosphorylated derivative (NADPH) have been explored in order to assess their potential as an intrinsic probe for cancer surgery. NADPH production is increased in cancer cells to quench reactive oxygen species and meet higher demands for biosynthesis, and has attractive fluorescent properties such as emission towards the visible part of the spectrum and a relatively long fluorescence lifetime upon binding to enzymes (~ 1 ā 6.5 ns) that helps discriminate against other endogenous species. Different environmental effects on NAD(P)H fluorescence are reported here, including an increase in lifetime upon oxygen removal, an ability to retain its fluorescent properties in a complex medium (a silica phantom) and its fluorescence lifetime also being distinguishable in a cell environment. In addition, the development of a miniaturized liquid light guide filter-based timecorrelated single photon counting fluorescence lifetime system is reported as a step towards time-resolved visual imaging in cancer surgery. This system has been demonstrated as being capable of accurately measuring NAD(P)H fluorescence lifetimes in both simple solvent and cellular environments
On the relativistic Lattice Boltzmann method for quark-gluon plasma simulations
In this paper, we investigate the recently developed lattice Boltzmann model
for relativistic hydrodynamics. To this purpose, we perform simulations of
shock waves in quark-gluon plasma in the low and high viscosities regime, using
three different computational models, the relativistic lattice Boltzmann (RLB),
the Boltzmann Approach Multi-Parton Scattering (BAMPS), and the viscous sharp
and smooth transport algorithm (vSHASTA). From the results, we conclude that
the RLB model departs from BAMPS in the case of high speeds and high
temperature(viscosities), the departure being due to the fact that the RLB is
based on a quadratic approximation of the Maxwell-J\"uttner distribution, which
is only valid for sufficiently low temperature and velocity. Furthermore, we
have investigated the influence of the lattice speed on the results, and shown
that inclusion of quadratic terms in the equilibrium distribution improves the
stability of the method within its domain of applicability. Finally, we assess
the viability of the RLB model in the various parameter regimes relevant to
ultra-relativistic fluid dynamics.Comment: 10 pages, 16 Figure
Topographic, Hydraulic, and Vegetative Controls on Bar and Island Development in Mixed BedrockāAlluvial, Multichanneled, Dryland Rivers
We investigate processes of bedrockācore bar and island development in a bedrockāinfluenced anastomosed reach of the Sabie River, Kruger National Park (KNP), eastern South Africa. For sites subject to alluvial stripping during an extreme flood event (~4470ā5630 m3 sā1) in 2012, preā and postāflood aerial photographs and LiDAR data, 2D morphodynamic simulations, and field observations reveal that the thickest surviving alluvial deposits tend to be located over bedrock topographic lows. At a simulated peak discharge (~4500 m3 sā1), most sediment (sand, fine gravel) is mobile but localized deposition on bedrock topographic highs is possible. At lower simulated discharges (<1000 m3 sā1), topographic highs are not submerged, and deposition occurs in lower elevation areas, particularly in areas disconnected from the main channels during falling stage. Field observations suggest that in addition to discharge, rainwash between floods may redistribute sediments from bedrock topographic highs to lower elevation areas, and also highlight the critical role of vegetation colonization in bar stability, and in trapping of additional sediment and organics. These findings challenge the assumptions of preferential deposition on topographic highs that underpin previous analyses of KNP river dynamics, and are synthesized in a new conceptual model that demonstrates how initial bedrock topographic lows become topographic highs (bedrock coreābars and islands) in the latter stages of sediment accumulation. The model provides particular insight into the development of mixed bedrockāalluvial anastomosing along the KNP rivers, but similar processes of bar/island development likely occur along numerous other bedrockāinfluenced rivers across dryland southern Africa and farther afield
C-terminal diversity within the p53 family accounts for differences in DNA binding and transcriptional activity
The p53 family is known as a family of transcription factors with functions in tumor suppression and development. Whereas the central DNA-binding domain is highly conserved among the three family members p53, p63 and p73, the C-terminal domains (CTDs) are diverse and subject to alternative splicing and post-translational modification. Here we demonstrate that the CTDs strongly influence DNA binding and transcriptional activity: while p53 and the p73 isoform p73Ī³ have basic CTDs and form weak sequence-specific proteināDNA complexes, the major p73 isoforms have neutral CTDs and bind DNA strongly. A basic CTD has been previously shown to enable sliding along the DNA backbone and to facilitate the search for binding sites in the complex genome. Our experiments, however, reveal that a basic CTD also reduces proteināDNA complex stability, intranuclear mobility, promoter occupancy in vivo, target gene activation and induction of cell cycle arrest or apoptosis. A basic CTD therefore provides both positive and negative regulatory functions presumably to enable rapid switching of protein activity in response to stress. The different DNA-binding characteristics of the p53 family members could therefore reflect their predominant role in the cellular stress response (p53) or developmental processes (p73)
An inter-subunit protein-peptide interface that stabilizes the specific activity and oligomerization of the AAA+ chaperone Reptin
The work was supported by: the Czech Science Foundation 16-20860S (PM, LH) and 16-07321S (BV, TH), the project MEYS ā NPS I ā LO1413, and MH CZ - DRO (MMCI, 00209805); the BBSRC RASOR consortium (BB/C511599/1; United Kingdom); Cancer Research UK (C21383/A6950); The International Centre for Cancer Vaccine Science project carried out within the International Research Agendas programme of the Foundation for Polish Science co-financed by the European Union under the European Regional Development Fund; A*STAR, Singapore and NSCC, Singapore.Reptin is a member of the AAA+ superfamily whose members can exist in equilibrium between monomeric apo forms and ligand bound hexamers. Inter-subunit protein-protein interfaces that stabilize Reptin in its oligomeric state are not well-defined. A self-peptide binding assay identified a protein-peptide interface mapping to an inter-subunit ārimā of the hexamer bridged by Tyrosine-340. A Y340A mutation reduced ADP-dependent oligomer formation using a gel filtration assay, suggesting that Y340 forms a dominant oligomer stabilizing side chain. The monomeric ReptinY340A mutant protein exhibited increased activity to its partner protein AGR2 in an ELISA assay, further suggesting that hexamer formation can preclude certain protein interactions. Hydrogen-deuterium exchange mass spectrometry (HDX-MS) demonstrated that the Y340A mutation attenuated deuterium suppression of Reptin in this motif in the presence of ligand. By contrast, the tyrosine motif of Reptin interacts with a shallower pocket in the hetero-oligomeric structure containing Pontin and HDX-MS revealed no obvious role of the Y340 side chain in stabilizing the Reptin-Pontin oligomer. Molecular dynamic simulations (MDS) rationalized how the Y340A mutation impacts upon a normally stabilizing inter-subunit amino acid contact. MDS also revealed how the D299N mutation can, by contrast, remove oligomer de-stabilizing contacts. These data suggest that the Reptin interactome can be regulated by a ligand dependent equilibrium between monomeric and hexameric forms through a hydrophobic inter-subunit protein-protein interaction motif bridged by Tyrosine-340. Significance Discovering dynamic protein-protein interactions is a fundamental aim of research in the life sciences. An emerging view of protein-protein interactions in higher eukaryotes is that they are driven by small linear polypeptide sequences; the linear motif. We report on the use of linear-peptide motif screens to discover a relatively high affinity peptide-protein interaction for the AAA+ and pro-oncogenic protein Reptin. This peptide interaction site was shown to form a āhot-spotā protein-protein interaction site, and validated to be important for ligand-induced oligomerization of the Reptin protein. These biochemical data provide a foundation to understand how single point mutations in Reptin can impact on its oligomerization and protein-protein interaction landscape.PostprintPeer reviewe
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