1,811 research outputs found
Affiliated mutual funds and analyst optimism
No full textPrior studies have shown that investment banking affiliations place pressure on analysts to produce optimistic recommendations on the investment bank’s stock-clients. Our analysis of a large sample of recommendations issued from 1995 through 2003 indicates that a mutual fund affiliation also affects analysts’ research. That is, analysts are likely to look favorably at stocks held by the affiliated mutual funds. Controlling for a variety of factors including the investment banking affiliation, we find that the greater the portfolio weight of a stock for the affiliated mutual funds, the more optimistic the analyst rating becomes when compared to the consensus. Reputation partly restrains the optimism of analyst recommendations. In fact, the presence of other institutional investors as shareholders of the recommended stocks curbs analyst optimism. Nevertheless, from 1999 through 2001, star analysts report the most optimism when they recommend stocks in the portfolios of affiliated mutual funds.Mutual funds ; Investment banking
When are Analyst Recommendation Changes Influential?
No full textNot all stock recommendation changes are equal. In a sample constructed to minimize the impact of confounding news, relatively few analyst recommendation changes are influential in the sense that they impact investors' beliefs about a firm in a way that could be noticed in that firm's stock returns. More than one-third of the stock-price reactions to analyst recommendation changes have the wrong sign and only approximately 10% have significant stock-price reactions at the 5% level using an extended market model. We find that the probability of an influential recommendation is higher for leader analysts, star analysts, away-from-consensus revisions, revisions issued contemporaneously with earnings forecasts, analysts with greater relative experience, and those with more accurate earnings estimates. Growth firms, small firms, high institutional ownership firms, and high prior turnover firms are also more likely to have influential stock recommendations. Strikingly, analyst recommendations are more likely to be influential after Reg FD and the settlement. Finally, influential recommendations are associated with increases in stock volatility and large absolute changes in consensus earnings forecasts.
When the payment mode affects the quality of advices. Financial analysts, fund managers, and brokerage commissions
No full text"Sell-side"analysts advise fund managers with recommendations to buy or sell a stock. But being compensated with commissions proportional to the amount traded can drive the analyst to bias his advice. In a two-agent model, it is notably shown that the probability of a biased equilibrium to occur increases with commission rate, but decreases with the weight of analyst rating. Moreover, the fund manager can cross-check the recommendation with his own signal–this may represent access to an in-house"buy-side analyst". The fund manager does not necessarily follow the sell-side analyst if its own signal is precise enough . The model hence provides a theoretical rationale for recent empirical results about the independance of sell-side analysts.Financial Analysts, Brokerage, Stock Recommendations.
Rapid screening for synthetic antidiabetic drug adulteration in herbal dietary supplements using direct analysis in real time mass spectrometry
No full textAdulteration of herbal supplements with synthetic drugs is illegal. A rapid and reliable method which utilizes direct analysis in real time mass spectrometry (DART-MS) was developed for the identification of seven synthetic antidiabetic drugs used as adulterants in herbal dietary supplements. The supplement sample was simply extracted with methanol/water by manually shaking several times and directly analyzed using DART-MS. The presence of synthetic drug adulterants was confirmed through the accurate m/z values and MS/MS data obtained via quadruple time of flight mass spectrometry (QTOF MS). Parameters for the DART source were systematically optimized, and the limits of detection (LODs) in herbal supplement matrices were measured. This method was successfully applied to examine five commercial herbal dietary supplements, and two of them proved to be adulterated with metformin without labeling
Analytical methods based on the light-scattering of plasmonic nanoparticles at the single particle level with dark-field microscopy imaging
No full textThis minireview summarizes analytical methods based on the light-scattering of plasmonic nanoparticles, primarily gold nanoparticles (AuNPs), at the single particle level from recent year publications. Examples are presented to illustrate simple and highly sensitive approaches based on AuNP localized surface plasmon resonance light-scattering with the dark-field microscopy imaging technology.National Natural Science Foundation of China [21475004, 21275011, 21535006]SCI(E)REVIEW2248-25614
Oligonucleotide-functionalized gold nanoparticles-enhanced QCM-D sensor for mercury(II) ions with high sensitivity and tunable dynamic range
No full textA quartz crystal microbalance with dissipation monitoring (QCM-D) sensor was developed for highly sensitive and specific detection of mercury(II) ions (Hg2+) with a tunable dynamic range, using oligonucleotide-functionalized gold nanoparticles (GNPs) for both frequency and dissipation amplification. The fabrication of the sensor employed a 'sandwich-type' strategy, and formation of T-Hg2+-T structures in linker DNA reduced the hybridization of the GNPs-tagged DNA on the gold electrode, which could be used as the molecular switch for Hg2+ sensing. This QCM-D mercury sensor showed a linear response of 10-200 nM, with detection limits of 4 nM and 7 nM for frequency and dissipation measurements, respectively. Moreover, the dynamic range of the sensor could be tuned by simply altering the concentration of linker DNA without designing new sensors in the cases where detection of Hg2+ at different levels is required. This sensor afforded excellent selectivity toward Hg2+ compared with other potential coexisting metal ions. The feasibility of the sensor was demonstrated by analyzing Hg2+-spiked tap- and lake-water samples with satisfactory recoveries. The proposed approach extended the application of the QCM-D system in metal ions sensing, and could be adopted for the detection of other analytes when complemented with the use of functional DNA structures
Hybridization chain reaction-based fluorescence immunoassay using DNA intercalating dye for signal readout
No full textA novel format of fluorescence immunosorbent assay based on the hybridization chain reaction (HCR) using a DNA intercalating dye for signal readout was constructed for the sensitive detection of targets, both in competitive and sandwich modes. In this platform, the capture and recognition processes are based on immunoreactions and the signal amplification depends on the enzyme-free, isothermal HCR-induced labelling event. After a competitive or a sandwich immunoreaction, a biotinylated capture DNA was bound to a biotinylated signal antibody through avidin, and triggered the HCR by two specific hairpins into a nicked double helix. Gene Finder (GF), a fluorescent probe for double-strand DNA, was intercalated in situ into the amplified chain to produce the fluorescence signal. The limit of detection (LOD) for rabbit IgG in competitive mode by HCR/GF immunoassay was improved at least 100-fold compared with the traditional fluorescence immunoassay using the fluorescein isothiocyanate-labelledstreptavidin or fluorescein isothiocyanate-labelled second antibody as the signal readout. The proposed fluorescence immunoassay was also demonstrated by using alpha-fetoprotein as the model target in sandwich mode, and showed a wide linear range from 28 ng mL(-1) to 20 mu g mL(-1) with a LOD of 6.0 ng mL(-1). This method also showed satisfactory analysis in spiked human serum, which suggested that it might have great potential for versatile applications in life science and point-of-care diagnostics.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000337125600025&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Chemistry, AnalyticalSCI(E)[email protected]; [email protected]
Monolith dip-it: a bifunctional device for improving the sensitivity of direct analysis in real time mass spectrometry
No full textA bifunctional monolith dip-it was fabricated and applied for improving the sensitivity of direct analysis in real time mass spectrometry (DART-MS). This monolith dip-it device was prepared by in situ polymerization of poly(BMA-EDMA-MAA) monolith in the glass capillary of dip-it. As a solid-phase microextraction (SPME) device, it showed strong affinity to four Sudan dyes through hydrophilic interaction and hydrogen bond interaction. As a sample loading device, it could be directly analyzed by DART-MS without organic solvent elution or laser desorption. As a result, this device is environmentally friendly, and used for fast analysis. Under optimized conditions, the limits of detection for four analytes were 5-10 ng mL(-1) and the linear ranges covered more than two orders of magnitude. Finally, the developed method has been applied for the analysis of chili powder and the recoveries for spiked analytes were in the range of 83.2% to 115.1% demonstrating that this device is an efficient sampler for DART-MS analysis and the proposed method could find more applications in different areas like food analysis.National Natural Science Foundation of China [21175008, 21275012]; Ministry of Science and Technology of China [2013YQ510391, 2012YQ090194-9]SCI(E)[email protected]; [email protected]
A dielectric barrier discharge ionization based interface for online coupling surface plasmon resonance with mass spectrometry
No full textThe online combination of surface plasmon resonance (SPR) with mass spectrometry (MS) could be beneficial for accurately acquiring molecular interaction data simultaneously with their structural information at high throughputs. In this work, a novel SPR-MS interface was developed using a dielectric barrier discharge ionization (DBDI) source. The DBDI source was placed in front of the MS inlet, generating an ionization plasma jet. A spray tip was set between the DBDI source outlet and the MS inlet, nebulizing the SPR sample solution. Using this interface, samples could first be studied by SPR, then sprayed and ionized, finally analyzed by MS. By analyzing model samples containing small-molecule drugs dissolved in salt containing solutions, the practicability of this SPR-DBDI-MS interface was proved, observing the consistent change of SPR and MS signals. Compared with our previously developed direct analysis in real time (DART) based SPR-MS interface, this new interface exhibited a higher and better tolerance to non-volatile salts, and different ionization capabilities for various samples. These results indicated that the interface could find further utilization in SPR-MS studies especially when physiological conditions were needed.National Instrumentation Program of China from the Chinese Ministry of Science and Technology [2012YQ090194-9]; National Natural Science Foundation of China [21275012]SCI(E)[email protected]; [email protected]
Analysis of endogenous nucleotides by single cell capillary electrophoresis-mass spectrometry
No full textAnalytical technologies that enable investigations at the single cell level facilitate a range of studies; here a lab-fabricated capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) platform was used to analyze anionic metabolites from individual Aplysia califomica neurons. The system employs a customized coaxial sheath-flow nanospray interface connected to a separation capillary, with the sheath liquid and separation buffer optimized to ensure a stable spray. The method provided good repeatability of separation and reliable detection sensitivity for 16 mono:, di- and triphosphate nucleosides. For a range of anionic analytes, including cyclic adenosine monophosphate (cAMP), adenosine diphosphate (ADP) and adenosine triphosphate (ATP), the detection limits were in the low nanomolar range (<22 nM). A large Aplysia R2 neuron was used to demonstrate the ability of CE-ESI-MS to quantitatively characterize anionic metabolites within individual cells, with 15 nucleotides and derivatives detected. Following the method validation process, we probed smaller, 60 gm diameter Aplysia sensory neurons where sample stacking was used as a simple on-line analyte preconcentration approach. The calculated energy balance ([ATP] + 0.5 x [ADP1)/(EAMP] + [ADP] + [ATP]) of these cells was comparable with the value obtained from bulk samples.Chemistry, AnalyticalSCI(E)[email protected]; [email protected]
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