2,718 research outputs found
Mass spectrometry-directed synthesis of early–late sulfide-bridged heterobimetallic complexes from the metalloligand [Pt₂(PPh₃)₄(μ-S)₂] and oxo compounds of vanadium(V), molybdenum(VI) and uranium(VI)
The metalloligand [Pt₂(PPh₃)₄(μ-S)₂] has been found to react with the transition metal oxo compounds, ammonium metavanadate, sodium molybdate, and the actinide complex uranyl nitrate to give sulfide-bridged heterobimetallic complexes [Pt₂(PPh₃)₄(μ₃-S)₂VO(OMe)₂]⁺, [Pt₂(PPh₃)₄(μ₃-S)₂MoO₂(OMe)]⁺, and [Pt₂(PPh₃)₄(μ₃-S)₂UO₂( ₂-NO₃)₂], respectively. Electrospray mass spectrometry (ESMS) was used to probe the reactivity of [Pt₂(PPh₃)₄(μ-S)₂] and thus identify likely targets for isolation and characterization. ESMS has also been used to investigate fragmentation pathways of the new species. No bimetallic species were detected with hydrated La(NO₃)₃or Th(NO₃)₄, or with the lanthanide shift reagent Eu(fod)₃ (fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate). X-Ray crystal structure determinations have been carried out on [Pt₂(PPh₃)₄(μ₃-S)₂VO(OMe)₂]⁺, 2, (as its hexafluorophosphate salt) and [Pt₂(PPh₃)₄(μ₃-S)₂UO₂( ₂-NO₃)₂], 4. The vanadium atom of 2 has a distorted square pyramidal geometry, while the uranium in 4 has the expected linear dioxo coordination geometry, with two bidentate nitrates and a bidentate {Pt₂S₂} moiety
Cytoadherence and virulence - the case of Plasmodium knowlesi malaria.
BACKGROUND: Cytoadherence of infected red blood cells to brain endothelium is causally implicated in malarial coma, one of the severe manifestations of falciparum malaria. Cytoadherence is mediated by specific binding of variant parasite antigens, expressed on the surface of infected erythrocytes, to endothelial receptors including, ICAM-1, VCAM and CD36. In fatal cases of severe falciparum malaria with coma, blood vessels in the brain are characteristically congested with infected erythrocytes. Brain sections from a fatal case of knowlesi malaria, but without coma, were similarly congested with infected erythrocytes. The objective of this study was to determine the binding phenotype of Plasmodium knowlesi infected human erythrocytes to recombinant human ICAM-1, VCAM and CD36.
METHODS: Five patients with PCR-confirmed P. knowlesi malaria were recruited into the study with consent between April and August 2010. Pre-treatment venous blood was washed and cultured ex vivo to increase the proportion of schizont-infected erythrocytes. Cultured blood was seeded into Petri dishes with triplicate areas coated with ICAM-1, VCAM and CD36. Following incubation at 37°C for one hour the dishes were washed and the number of infected erythrocytes bound/mm2 to PBS control areas and to recombinant human ICAM-1 VCAM and CD36 coated areas were recorded. Each assay was performed in duplicate. Assay performance was monitored with the Plasmodium falciparum clone HB3.
RESULTS: Blood samples were cultured ex vivo for up to 14.5 h (mean 11.3 ± 1.9 h) to increase the relative proportion of mature trophozoite and schizont-infected red blood cells to at least 50% (mean 65.8 ± 17.51%). Three (60%) isolates bound significantly to ICAM-1 and VCAM, one (20%) isolate bound to VCAM and none of the five bound significantly to CD36.
CONCLUSIONS: Plasmodium knowlesi infected erythrocytes from human subjects bind in a specific but variable manner to the inducible endothelial receptors ICAM-1 and VCAM. Binding to the constitutively-expressed endothelial receptor CD36 was not detected. Further work will be required to define the pathological consequences of these interactions
Heritage reporting by the Australian Public sector:possibilities from the concepts of new public governance
Purpose: The purpose of this paper is to contribute to the future development of heritage reporting in Australia. Public sector reporting of heritage has been a long-standing issue, due to shortcomings in (sector-neutral) for-profit-based financial reporting standards. Australia’s sector-neutral approach does not meet public sector users’ information needs. The authors develop a heritage reporting model to balance community and other stakeholders’ interests and address prior critiques. Design/methodology/approach: The paper reviews heritage reporting requirements in Anglo-Western Countries, and analyses commentaries and research publications. It evaluates the existing reporting requirements in the context of new public management (which focusses on information and efficiency) and new public governance (NPG) (focussing on balancing interests and quality). Findings: The paper proposes an NPG-based heritage reporting model which includes indicators of performance on the five UNESCO (1972) dimensions and operational guidelines issued by UNESCO (2015). These are identification, presentation, protection, conservation and transmission. The proposed model is consistent with the notion of US SFFAS 29 (the standard for Federal entities). Not all heritage must be capitalised and hence attachment of monetary value, but detailed disclosures are necessary. Research limitations/implications: The authors expect the proposed heritage reporting model to better serve users of heritage information compared to the present Australian Accounting Standards Board 116: Property, Plant and Equipment. Originality/value: The authors’ proposed model of heritage reporting attempts to answer Carnegie and Wolnizer’s (1995, 1999) six questions, addresses decades of concerns raised in previous literature and provides a new perspective to heritage reporting based on NPG that should better serve users’ needs
Emerging Technologies and Research Challenges for 5G Wireless Networks
As the take-up of Long Term Evolution (LTE)/4G cellular accelerates, there is
increasing interest in technologies that will define the next generation (5G)
telecommunication standard. This paper identifies several emerging technologies
which will change and define the future generations of telecommunication
standards. Some of these technologies are already making their way into
standards such as 3GPP LTE, while others are still in development.
Additionally, we will look at some of the research problems that these new
technologies pose.Comment: Accepted for publication in IEEE Wireless Communications April 201
Five Simple and Low Maintenance Investing Strategies: Seeking an Automated Investing System
The purpose of the paper is to examine five different investment strategies which are known to be easily implemented by ordinary investors: (1) S&P 500 strategy, (2) No OTC & No ADR (NoOtcAdr) strategy, (3) Warren Buffett’s stock market indicator-based strategy, (4) Federal Reserve Bank’s monetary policy-based strategy, and (5) Joel Greenblatt’s magic formula strategy. Among a large number of minimal maintenance strategies available, we investigate the efficacy of these five investment strategies because these strategies are extremely simple to implement and require little time commitment for investment research. Once they are set up, they will be maintenance free. Based on our findings and analysis, we propose a pair of options to retail investors, depending on their time commitment and risk tolerance level. Among five investment strategies, investors with high-risk tolerance may find merits in the Fed’s monetary policy-based strategy, whereas investors with low-risk tolerance may find Buffett’s stock market indicator-based strategy attractive. Keywords: Low maintenance investing strategies; Fed funds rate; Greenblatt’s magic formula; Sector rotation, Warren Buffett stock market indicator DOI: 10.7176/RJFA/11-2-01 Publication date: January 31st 202
Pixel-wise classification in graphene-detection with tree-based machine learning algorithms
Mechanical exfoliation of graphene and its identification by optical
inspection is one of the milestones in condensed matter physics that sparked
the field of 2D materials. Finding regions of interest from the entire sample
space and identification of layer number is a routine task potentially amenable
to automatization. We propose supervised pixel-wise classification methods
showing a high performance even with a small number of training image datasets
that require short computational time without GPU. We introduce four different
tree-based machine learning algorithms -- decision tree, random forest, extreme
gradient boost, and light gradient boosting machine. We train them with five
optical microscopy images of graphene, and evaluate their performances with
multiple metrics and indices. We also discuss combinatorial machine learning
models between the three single classifiers and assess their performances in
identification and reliability. The code developed in this paper is open to the
public and will be released at github.com/gjung-group/Graphene_segmentation.Comment: 12 pages, 6 figure
Probing the Spatial Distribution of Extrasolar Planets with Gravitational Microlensing
Under the current microlensing planet search strategy of monitoring events
caused by stellar-mass lenses, only planets located within a narrow region of
separations from central stars can be effectively detected. However, with the
dramatic increase of the monitoring frequency, two additional populations of
free-floating and wide-orbit planets can be detected. In this paper, we
investigate the lensing properties of events caused by wide-orbit planets and
find that the light curves of a significant fraction of these events will
exhibit signatures of central stars, enabling one to distinguish them from
those caused by free-floating planets. Due to the large primary/planet mass
ratio, the effect of the central star endures to considerable separations. We
find that for a Jupiter-mass planet the signatures of the central star can be
detected with fractional deviations of > 5% from the best-fitting single-lens
light curves for > 80% of events caused by bound planets with separations < 10
AU and the probability is still substantial for planets with separations up to
20 AU. Therefore, detecting a large sample of these events will provide useful
information about the distribution of extrasolar planets around their central
stars. Proper estimation of the probability of distinguishing events caused by
wide-orbit planets from those caused by free-floating planets will be important
for the correct determination of the frequency of free-floating planets, whose
microlensing sample will be contaminated by wide-orbits planets.Comment: total 7 pages, including 4 figures, ApJ, submitte
A Search for Hydroxylamine (NH2OH) toward Select Astronomical Sources
Observations of 14 rotational transitions of hydroxylamine (NH2OH) using the
NRAO 12 m Telescope on Kitt Peak are reported towards IRC+10216, Orion KL,
Orion S, Sgr B2(N), Sgr B2(OH), W3IRS5, and W51M. Although recent models
suggest the presence of NH2OH in high abundance, these observations resulted in
non-detection. Upper limits are calculated to be as much as six orders of
magnitude lower than predicted by models. Possible explanations for the lower
than expected abundance are explored.Comment: 18 pages, 3 figures, 3 table
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