2,071 research outputs found
AN EMPIRICAL EXAMINATION OF THE DETERMINANTS OF ELECTRONIC COMMUNICATIONS TECHNOLOGY USE AND ITS IMPACT ON SUPERVISORSUBORDINATE INTERACTIONS
Continued advancement in computer and telecommunications technology provide new options for organizational restructuring and process redesign. A common area of activity is the use of a combination of computer and telecommunicalion technology to operate and effectively support remote work sites. This paper provides preliminary findings regarding the factors determining the use of electronic communications technology and the impact of its use on supervisor-subordinate communications where the supervisor is located a[ the core organization and the subordinate is located at a remote site. The sample consists of eighty-five subordinates and fifty-seven supervisors based on 360 questionnaires from three major public accounting firms. Results indicate that accessibility to the technology, a critical mass of communication partners, the social symbolism of the technology, and the organization of work are Ihe most important factors associated with communication media use. Electronic mail is highly dependent on network externalities and some of the more popular technologies such as voice mail and facsimile machines were used with equivalent frequency in core and remote localions. As predicted, supervisor-subordinate interactions were affected by the supervisor-subordinate relationship and the organization of work. 25
Synthetic metabolons for metabolic engineering.
Journal ArticleResearch Support, Non-U.S. Gov'tReviewThis is a pre-copyedited, author-produced PDF of an article accepted for publication in Journal of Experimental Botany following peer review. The definitive publisher-authenticated version J. Exp. Bot. (2014) 65 (8) pp. 1947-1954 is available online at: http://jxb.oxfordjournals.org/content/65/8/1947It has been proposed that enzymes can associate into complexes (metabolons) that increase the efficiency of metabolic pathways by channelling substrates between enzymes. Metabolons may increase flux by increasing the local concentration of intermediates, decreasing the concentration of enzymes needed to maintain a given flux, directing the products of a pathway to a specific subcellular location or minimizing the escape of reactive intermediates. Metabolons can be formed by relatively loose non-covalent protein-protein interaction, anchorage to membranes, and (in bacteria) by encapsulation of enzymes in protein-coated microcompartments. Evidence that non-coated metabolons are effective at channelling substrates is scarce and difficult to obtain. In plants there is strong evidence that small proportions of glycolytic enzymes are associated with the outside of mitochondria and are effective in substrate channelling. More recently, synthetic metabolons, in which enzymes are scaffolded to synthetic proteins or nucleic acids, have been expressed in microorganisms and these provide evidence that scaffolded enzymes are more effective than free enzymes for metabolic engineering. This provides experimental evidence that metabolons may have a general advantage and opens the way to improving the outcome of metabolic engineering in plants by including synthetic metabolons in the toolbox
Principal variable selection to explain grain yield variation in winter wheat from features extracted from UAV imagery
Background: Automated phenotyping technologies are continually advancing the breeding process. However, collecting various secondary traits throughout the growing season and processing massive amounts of data still take great efforts and time. Selecting a minimum number of secondary traits that have the maximum predictive power has the potential to reduce phenotyping efforts. The objective of this study was to select principal features extracted from UAV imagery and critical growth stages that contributed the most in explaining winter wheat grain yield. Five dates of multispectral images and seven dates of RGB images were collected by a UAV system during the spring growing season in 2018. Two classes of features (variables), totaling to 172 variables, were extracted for each plot from the vegetation index and plant height maps, including pixel statistics and dynamic growth rates. A parametric algorithm, LASSO regression (the least angle and shrinkage selection operator), and a non-parametric algorithm, random forest, were applied for variable selection. The regression coefficients estimated by LASSO and the permutation importance scores provided by random forest were used to determine the ten most important variables influencing grain yield from each algorithm.
Results: Both selection algorithms assigned the highest importance score to the variables related with plant height around the grain filling stage. Some vegetation indices related variables were also selected by the algorithms mainly at earlier to mid growth stages and during the senescence. Compared with the yield prediction using all 172 variables derived from measured phenotypes, using the selected variables performed comparable or even better. We also noticed that the prediction accuracy on the adapted NE lines (r = 0.58–0.81) was higher than the other lines (r = 0.21–0.59) included in this study with different genetic backgrounds.
Conclusions: With the ultra-high resolution plot imagery obtained by the UAS-based phenotyping we are now able to derive more features, such as the variation of plant height or vegetation indices within a plot other than just an averaged number, that are potentially very useful for the breeding purpose. However, too many features or variables can be derived in this way. The promising results from this study suggests that the selected set from those variables can have comparable prediction accuracies on the grain yield prediction than the full set of them but possibly resulting in a better allocation of efforts and resources on phenotypic data collection and processing
Antisense Suppression of the Small Chloroplast Protein CP12 in Tobacco Alters Carbon Partitioning and Severely Restricts Growth
Abstract
The thioredoxin-regulated chloroplast protein CP12 forms a multienzyme complex with the Calvin-Benson cycle enzymes phosphoribulokinase (PRK) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). PRK and GAPDH are inactivated when present in this complex, a process shown in vitro to be dependent upon oxidized CP12. The importance of CP12 in vivo in higher plants, however, has not been investigated. Here, antisense suppression of CP12 in tobacco (Nicotiana tabacum) was observed to impact on NAD-induced PRK and GAPDH complex formation but had little effect on enzyme activity. Additionally, only minor changes in photosynthetic carbon fixation were observed. Despite this, antisense plants displayed changes in growth rates and morphology, including dwarfism and reduced apical dominance. The hypothesis that CP12 is essential to separate oxidative pentose phosphate pathway activity from Calvin-Benson cycle activity, as proposed in cyanobacteria, was tested. No evidence was found to support this role in tobacco. Evidence was seen, however, for a restriction to malate valve capacity, with decreases in NADP-malate dehydrogenase activity (but not protein levels) and pyridine nucleotide content. Antisense repression of CP12 also led to significant changes in carbon partitioning, with increased carbon allocation to the cell wall and the organic acids malate and fumarate and decreased allocation to starch and soluble carbohydrates. Severe decreases were also seen in 2-oxoglutarate content, a key indicator of cellular carbon sufficiency. The data presented here indicate that in tobacco, CP12 has a role in redox-mediated regulation of carbon partitioning from the chloroplast and provides strong in vivo evidence that CP12 is required for normal growth and development in plants.</jats:p
Patient-centred approaches to providing care at HIV diagnosis: perspectives from healthcare and peer-support workers
Background. Early uptake of HIV treatment among those newly diagnosed with HIV can improve
individual health and prevent onward transmission. Patient-centred care is considered an important
aspect in health care, the management of HIV, and can improve uptake of and adherence to HIV
treatments. Methods. Semi-structured interviews were conducted with sexual health clinicians
(n, 10) and HIV support workers (n, 4) to understand how they approached HIV diagnosis
delivery and care immediately thereafter. Results. Our thematic analysis identified three
themes: (1) centring patient needs at diagnosis; (2) assessing patients’ readiness to begin
treatment; and (3) referrals to psychosocial support services. Our findings highlight centring
patients was an important aspect of how participants delivered HIV diagnoses. By taking this
approach, clinicians were best able to consider patient readiness to initiate treatment and
referrals to social support services. Conclusions. Given HIV diagnoses are increasingly
occurring in generalist health services, our findings offer an important opportunity to learn from
the experiences of specialist sexual health clinicians and HIV support workers
Identification of Differentially Expressed Proteins in Murine Embryonic and Postnatal Cortical Neural Progenitors
BACKGROUND: The central nervous system (CNS) develops from a heterogeneous pool of neural stem and progenitor cells (NSPC), the underlying differences among which are poorly understood. The study of NSPC would be greatly facilitated by the identification of additional proteins that mediate their function and that would distinguish amongst different progenitor populations. METHODOLOGY/PRINCIPAL FINDINGS: To identify membrane and membrane-associated proteins expressed by NSPC, we used a proteomics approach to profile NSPC cultured as neurospheres (NS) isolated from the murine cortex during a period of neurogenesis (embryonic day 11.5, E11.5), as compared to NSPC isolated at a peak of gliogenesis (postnatal day 1, P0) and to differentiated E11.5 NS. 54 proteins were identified with high expression in E11.5 NS, including the TrkC receptor, several heterotrimeric G proteins, and the Neogenin receptor. 24 proteins were identified with similar expression in E11.5 and P0 NS over differentiated E11.5 NS, and 13 proteins were identified with high expression specifically in P0 NS compared to E11.5 NS. To illustrate the potential relevance of these identified proteins to neural stem cell biology, the function of Neogenin was further studied. Using Fluorescence Activated Cell Sorting (FACS) analysis, expression of Neogenin was associated with a self-renewing population present in both E11.5 and adult subventricular zone (SVZ) NS but not in P0 NS. E11.5 NS expressed a putative Neogenin ligand, RGMa, and underwent apoptosis when exposed to a ligand-blocking antibody. CONCLUSIONS/SIGNIFICANCE: There are fundamental differences between the continuously self-renewing and more limited progenitors of the developing cortex. We identified a subset of differentially expressed proteins that serve not only as a set of functionally important proteins, but as a useful set of markers for the subsequent analysis of NSPC. Neogenin is associated with the continuously self-renewing and neurogenic cells present in E11.5 cortical and adult SVZ NS, and the Neogenin/RGMa receptor/ligand pair may regulate cell survival during development
Functional reconstruction of a eukaryotic-like E1/E2/(RING) E3 ubiquitylation cascade from an uncultured archaeon.
The covalent modification of protein substrates by ubiquitin regulates a diverse range of critical biological functions. Although it has been established that ubiquitin-like modifiers evolved from prokaryotic sulphur transfer proteins it is less clear how complex eukaryotic ubiquitylation system arose and diversified from these prokaryotic antecedents. The discovery of ubiquitin, E1-like, E2-like and small-RING finger (srfp) protein components in the Aigarchaeota and the Asgard archaea superphyla has provided a substantive step toward addressing this evolutionary question. Encoded in operons, these components are likely representative of the progenitor apparatus that founded the modern eukaryotic ubiquitin modification systems. Here we report that these proteins from the archaeon Candidatus 'Caldiarchaeum subterraneum' operate together as a bona fide ubiquitin modification system, mediating a sequential ubiquitylation cascade reminiscent of the eukaryotic process. Our observations support the hypothesis that complex eukaryotic ubiquitylation signalling pathways have developed from compact systems originally inherited from an archaeal ancestor
3.6 and 4.5 m Phase Curves of the Highly-Irradiated Hot Jupiters WASP-19b and HAT-P-7b
We analyze full-orbit phase curve observations of the transiting hot Jupiters
WASP-19b and HAT-P-7b at 3.6 and 4.5 m obtained using the Spitzer Space
Telescope. For WASP-19b, we measure secondary eclipse depths of and at 3.6 and 4.5 m, which are consistent
with a single blackbody with effective temperature K. The
measured 3.6 and 4.5 m secondary eclipse depths for HAT-P-7b are
and , which are well-described by a
single blackbody with effective temperature K. Comparing the phase
curves to the predictions of one-dimensional and three-dimensional atmospheric
models, we find that WASP-19b's dayside emission is consistent with a model
atmosphere with no dayside thermal inversion and moderately efficient day-night
circulation. We also detect an eastward-shifted hotspot, suggesting the
presence of a superrotating equatorial jet. In contrast, HAT-P-7b's dayside
emission suggests a dayside thermal inversion and relatively inefficient
day-night circulation; no hotspot shift is detected. For both planets, these
same models do not agree with the measured nightside emission. The
discrepancies in the model-data comparisons for WASP-19b might be explained by
high-altitude silicate clouds on the nightside and/or high atmospheric
metallicity, while the very low 3.6 m nightside planetary brightness for
HAT-P-7b may be indicative of an enhanced global C/O ratio. We compute Bond
albedos of 0 ( at ) and for WASP-19b and
HAT-P-7b, respectively. In the context of other planets with thermal phase
curve measurements, we show that WASP-19b and HAT-P-7b fit the general trend of
decreasing day-night heat recirculation with increasing irradiation.Comment: 22 pages, 29 figures, accepted by Ap
Observational consequences of fine structure line optical depths on infrared spectral diagnostics
It has long been known that infrared fine structure lines of abundant ions,
like the [O III] 88 micron line, can become optically thick in H II regions
under certain high luminosity conditions. This could mitigate their potential
as diagnostic tools, especially if the source is too dusty for optical
spectroscopy to otherwise determine the system's parameters. We examined a
series of photoionization calculations which were designed to push the nebulae
into the limit where many IR lines should be quite optically thick. We find
that radiative transfer effects do not significantly change the observed
emission line spectrum. This is due to a combination of grain absorption of the
hydrogen ionizing continuum and the fact that the correction for stimulated
emission in these lines is large. Given these results, and the likelihood that
real objects have non-thermal line broadening, it seems unlikely that line
optical depth presents a problem in using these lines as diagnostics of the
physical conditions or chemical composition.Comment: 16 pages, 4 figures, to be published in the February 2003 issue of
the PAS
Cultivar fingerprinting and SNP-based pedigree reconstruction in Danish heritage apple cultivars utilizing genotypic data from multiple germplasm collections in the world
Heirloom Danish apple cultivars are historically and pomologically important, part of the cultural heritage, and have valuable adaptation to regional climate conditions. However, lack of information about their genetic identity and pedigree relatedness with other cultivars hampers proper cultivar identification, germplasm curation, genebank management, and future regional breeding efforts. Many Danish apple cultivars are maintained in the national collection “The Pometum”, maintaining around 850 apple accessions. Additional material is maintained in public or private Danish collections. However, no information exists regarding genotypic duplicates between these collections and germplasm collections in other countries, pedigree inferences across collections, and genotypically unique accessions at the genebank level. To provide such information, 976 accessions from Denmark were genotyped with simple sequence repeat (SSR) markers and the Illumina Infinium 20K single nucleotide polymorphism (SNP) array. The resulting genotypic data were compared to large databases of genotypic data from germplasm collections in multiple countries to identify genotypic duplicates and conduct pedigree reconstruction. The germplasm maintains 305 unique genotypic profiles which were not found in other germplasm collections. The study exposed previously unknown synonyms, accessions not true-to-type, and novel pedigree relationships involving accessions from multiple collection sites. The most frequent parents of Danish germplasm were ‘Hvid Vinter Pigeon’ and ‘Cox’s Orange Pippin’ whereas ‘Reinette Franche’ was the most common grandparent. The accession-level information will benefit germplasm curation, cultivar identification, genebank management, and future breeding efforts, and shed new light on cultivar history and origi
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