82 research outputs found
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Booms and busts in commodity markets: bubbles or fundamentals?
This paper considers whether there were periodically collapsing rational speculative bubbles in commodity prices over a 40-year period from the late 1960s. We apply a switching regression approach to a broad range of commodities using two different measures of fundamental values—estimated from convenience yields and from a set of macroeconomic factors believed to affect commodity demand. We find reliable evidence for bubbles only among crude oil and feeder cattle, showing the popular belief that the extreme price movements observed in commodity markets were caused by pure speculation to be unsustainabl
DIGE Proteome Analysis Reveals Suitability of Ischemic Cardiac In Vitro Model for Studying Cellular Response to Acute Ischemia and Regeneration
Proteomic analysis of myocardial tissue from patient population is suited to yield insights into cellular and molecular mechanisms taking place in cardiovascular diseases. However, it has been limited by small sized biopsies and complicated by high variances between patients. Therefore, there is a high demand for suitable model systems with the capability to simulate ischemic and cardiotoxic effects in vitro, under defined conditions. In this context, we established an in vitro ischemia/reperfusion cardiac disease model based on the contractile HL-1 cell line. To identify pathways involved in the cellular alterations induced by ischemia and thereby defining disease-specific biomarkers and potential target structures for new drug candidates we used fluorescence 2D-difference gel electrophoresis. By comparing spot density changes in ischemic and reperfusion samples we detected several protein spots that were differentially abundant. Using MALDI-TOF/TOF-MS and ESI-MS the proteins were identified and subsequently grouped by functionality. Most prominent were changes in apoptosis signalling, cell structure and energy-metabolism. Alterations were confirmed by analysis of human biopsies from patients with ischemic cardiomyopathy
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The dynamics of commodity return comovements
We compare factor models with respect to their ability to explain commodity futures return comovements. A simple one-factor model based on the first principal component extracted from a panel of commodity returns outperforms a macroeconomic model, and explains most of the realized comovements. We find that intersectoral correlations display more time variations than intrasectoral correlations. Dissecting the evidence further, we find that comovements are driven by the variation of the factor as opposed to exposure to it. Our results cast doubt on the persistence of the effects of financialization and emphasize the importance of the dynamics of the factor variance
The Na+/H+ Exchanger Controls Deoxycholic Acid-Induced Apoptosis by a H+-Activated, Na+-Dependent Ionic Shift in Esophageal Cells
Apoptosis resistance is a hallmark of cancer cells. Typically, bile acids induce apoptosis. However during gastrointestinal (GI) tumorigenesis the cancer cells develop resistance to bile acid-induced cell death. To understand how bile acids induce apoptosis resistance we first need to identify the molecular pathways that initiate apoptosis in response to bile acid exposure. In this study we examined the mechanism of deoxycholic acid (DCA)-induced apoptosis, specifically the role of Na+/H+ exchanger (NHE) and Na+ influx in esophageal cells. In vitro studies revealed that the exposure of esophageal cells (JH-EsoAd1, CP-A) to DCA (0.2 mM -0.5 mM) caused lysosomal membrane perturbation and transient cytoplasmic acidification. Fluorescence microscopy in conjunction with atomic absorption spectrophotometry demonstrated that this effect on lysosomes correlated with influx of Na+, subsequent loss of intracellular K+, an increase of Ca2+ and apoptosis. However, ethylisopropyl-amiloride (EIPA), a selective inhibitor of NHE, prevented Na+, K+ and Ca2+ changes and caspase 3/7 activation induced by DCA. Ouabain and amphotericin B, two drugs that increase intracellular Na+ levels, induced similar changes as DCA (ion imbalance, caspase3/7 activation). On the contrary, DCA-induced cell death was inhibited by medium with low a Na+ concentrations. In the same experiments, we exposed rat ileum ex-vivo to DCA with or without EIPA. Severe tissue damage and caspase-3 activation was observed after DCA treatment, but EIPA almost fully prevented this response. In summary, NHE-mediated Na+ influx is a critical step leading to DCA-induced apoptosis. Cells tolerate acidification but evade DCA-induced apoptosis if NHE is inhibited. Our data suggests that suppression of NHE by endogenous or exogenous inhibitors may lead to apoptosis resistance during GI tumorigenesis
Rationale and design of a prospective substudy of clinical endpoint adjudication processes within an investigator-reported randomised controlled trial in patients with coronary artery disease: the GLOBAL LEADERS Adjudication Sub-StudY (GLASSY)
pragmatic and superiority randomised controlled trial
designed to challenge the current treatment paradigm of dual
antiplatelet therapy (DAPT) for 12 months followed by aspirin
monotherapy among patients undergoing percutaneous
coronary intervention. By design, all study endpoints are
investigator reported (IR) and not subject to formal adjudication
by an independent Clinical Event Committee (CEC), which may
introduce detection, reporting or ascertainment bias.
Methods and analysis We designed the GLOBAL LEADERS
Adjudication Sub-StudY (GLASSY) to prospectively implement,
in a large sample of patients enrolled within the GLOBAL
LEADERS trial (7585 of 15 991, 47.5%), an independent
adjudication process of reported and unreported potential
endpoints, using standardised CEC procedures, in order
to assess whether 23-month ticagrelor monotherapy
(90mg twice daily) after 1-month DAPT is non-inferior to a
standard regimen of DAPT for 12 months followed by aspirin
monotherapy for the primary efficacy endpoint of death, nonfatal myocardial infarction, non-fatal stroke or urgent target
vessel revascularisation and superior for the primary safety
endpoint of type 3 or 5 bleeding according to the Bleeding
Academic Research Consortium criteria. This study will
comprehensively assess the comparative safety and efficacy
of the two tested antithrombotic strategies on CEC-adjudicated
ischaemic and bleeding endpoints and will provide insights
into the role of a standardised CEC adjudication process on
the interpretation of study findings by quantifying the level
of concordance between IR-reported and CEC-adjudicated
events.
Ethics and dissemination GLASSY has been approved
by local ethics committee of all study sites and/or by the
central ethics committee for the country depending on
country-specific regulations. In all cases, they deemed that
it was not neces
Non-Standard Errors
In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence-generating process (EGP). We claim that EGP variation across researchers adds uncertainty: Non-standard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for better reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants
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Non-standard errors
In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence generating process (EGP). We claim that EGP variation across researchers adds uncertainty: Non-standard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for better reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants
Extrinsic Optical Fiber Sensor for Medical Audiometric Applications
The paper presents optical fiber sensor designed for medical audiometric measurements. Currently, highly precise audiometric examinations require attachment of reflective element inside the ear. We propose alternative contactless optical and non-invasive method for audiometric applications. Presented sensor utilizes extrinsic intensity modulation combined with interferometric method to measure low amplitude vibrations with flat frequency response curve and no resonance effects. Experiment was performed with tympanic membrane model stimulated by external loudspeaker. Experimental results show usage possibility of presented sensor for laryngological and audiometric tests of ear membrane response, which is important for both diagnosis and implants sensitivity fitting for people with hearing deficits
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