Rankings and risk-taking in the finance industry

Rankings are a pervasive feature of the finance industry. Although they have no direct monetary consequences, rankings provide utility for intrinsic (positive self-image) and extrinsic (status) reasons. We recruit a unique subject pool of 204 financial professionals and investigate how anonymous rankings influence risk-taking in investment decisions. We find that rankings increase risk-taking because of financial professionals' desire for positive self-image. This particularly applies to underperformers, who take the highest risks. Incentivizing rankings monetarily does not further increase risk-taking. In a comparative study with 432 students we find that student behavior is not driven by rankings

The topology of metabolic isotope labeling networks

<p>Abstract</p> <p>Background</p> <p>Metabolic Flux Analysis (MFA) based on isotope labeling experiments (ILEs) is a widely established tool for determining fluxes in metabolic pathways. Isotope labeling networks (ILNs) contain all essential information required to describe the flow of labeled material in an ILE. Whereas recent experimental progress paves the way for high-throughput MFA, large network investigations and exact statistical methods, these developments are still limited by the poor performance of computational routines used for the evaluation and design of ILEs. In this context, the global analysis of ILN topology turns out to be a clue for realizing large speedup factors in all required computational procedures.</p> <p>Results</p> <p>With a strong focus on the speedup of algorithms the topology of ILNs is investigated using graph theoretic concepts and algorithms. A rigorous determination of all cyclic and isomorphic subnetworks, accompanied by the global analysis of ILN connectivity is performed. Particularly, it is proven that ILNs always brake up into a large number of small strongly connected components (SCCs) and, moreover, there are natural isomorphisms between many of these SCCs. All presented techniques are universal, i.e. they do not require special assumptions on the network structure, bidirectionality of fluxes, measurement configuration, or label input. The general results are exemplified with a practically relevant metabolic network which describes the central metabolism of <it>E. coli </it>comprising 10390 isotopomer pools.</p> <p>Conclusion</p> <p>Exploiting the topological features of ILNs leads to a significant speedup of all universal algorithms for ILE evaluation. It is proven in theory and exemplified with the <it>E. coli </it>example that a speedup factor of about 1000 compared to standard algorithms is achieved. This widely opens the door for new high performance algorithms suitable for high throughput applications and large ILNs. Moreover, for the first time the global topological analysis of ILNs allows to comprehensively describe and understand the general patterns of label flow in complex networks. This is an invaluable tool for the structural design of new experiments and the interpretation of measured data.</p

Variability in Ultrasound Education among Emergency Medicine Residencies

Objective: Education in emergency ultrasound (EUS) has become an essential part of emergency medicine (EM) resident training. In 2009, comprehensive residency training guidelines were published to ensure proficiency in ultrasound education. The American College of Emergency Physicians (ACEP) recommends that 150 ultrasound exams be performed for physician competency. Our goal is to evaluate the current ultrasound practices among EM residency programs and assess the need for further formalization of EUS training.Methods: We generated a survey using an online survey tool and administered via the internet. The survey consisted of 25 questions that included multiple choice and free text answers. These online survey links were sent via email to EM ultrasound directors at all 149 American College of Graduate Medical Education EM residency programs in April 2008. We surveyed programs regarding EUS curriculum and residency proficiency requirements and descriptive statistics were used to report the survey findings.Results: Sixty-five residency programs responded to the survey. The average number of ultrasound exams required by programs for EUS competency was 137 scans. However, the majority of programs 42/65 (64%) require their residents to obtain 150 scans or greater for competency. Fifty-one out of 64 (79%) programs reported having a structured ultrasound curriculum while 14/64 (21%) of programs reported that EUS training is primarily resident self-directed. In terms of faculty credentialing, 29/62 (47%) of residency programs have greater than 50% of faculty credentialed. Forty-four out of 61 (72%) programs make EUS a required rotation. Thirty-four out of 63 (54%) programs felt that they were meeting all their goals for resident EUS education.Conclusion: Currently discrepancies exist between EM residency programs in ultrasound curriculum and perceived needs for achieving proficiency in EUS. Although a majority of residency programs require 150 ultrasound exams or more to achieve resident competency, overall the average number of scans required by all programs is 137 exams. This number is less than that recommended by ACEP for physician competency. These data suggest that guidelines are needed to help standardize ultrasound training for all EM residency programs. [West J Emerg Med 2010; 11(4):314-318.

What drives risk perception? A global survey with financial professionals and laypeople

Contains fulltext : 209823.pdf (preprint version ) (Open Access)01 juli 202026 p

Kinetoplastid RNA editing involves a 3′ nucleotidyl phosphatase activity

Mitochondrial pre-messenger RNAs (pre-mRNAs) in African trypanosomes require RNA editing in order to mature into functional transcripts. The process involves the addition and/or removal of U nucleotides and is mediated by a high-molecular-mass complex, the editosome. Editosomes catalyze the reaction through an enzyme-driven pathway that includes endo/exoribonuclease, terminal uridylate transferase and RNA ligase activities. Here we show that editing involves an additional reaction step, a 3′ nucleotidyl phosphatase activity. The activity is associated with the editing complex and we demonstrate that the editosomal proteins TbMP99 and TbMP100 contribute to the activity. Both polypeptides contain endo-exonuclease-phosphatase domains and we show that gene ablation of either one of the two polypeptides is compensated by the other protein. However, simultaneous knockdown of both genes results in trypanosome cells with reduced 3′ nucleotidyl phosphatase and reduced editing activity. The data provide a rationale for the exoUase activity of the editosomal protein TbMP42, which generates nonligatable 3′ phosphate termini. Opposing phosphates at the two pre-mRNA cleavage fragments likely function as a roadblock to prevent premature ligation

EARL compliance measurements on the biograph vision Quadra PET/CT system with a long axial field of view.

BACKGROUND Our aim was to determine sets of reconstruction parameters for the Biograph Vision Quadra (Siemens Healthineers) PET/CT system that result in quantitative images compliant with the European Association of Nuclear Medicine Research Ltd. (EARL) criteria. Using the Biograph Vision 600 (Siemens Healthineers) PET/CT technology but extending the axial field of view to 106 cm, gives the Vision Quadra currently an around fivefold higher sensitivity over the Vision 600 with otherwise comparable spatial resolution. Therefore, we also investigated how the number of incident positron decays-i.e., exposure-affects EARL compliance. This will allow estimating a minimal acquisition time or a minimal applied dose in clinical scans while retaining data comparability. METHODS We measured activity recovery curves on a NEMA IEC body phantom filled with an aqueous 18F solution and a sphere to background ratio of 10-1 according to the latest EARL guidelines. Reconstructing 3570 image sets with varying OSEM PSF iterations, post-reconstruction Gaussian filter full width at half maximum (FWHM), and varying exposure from 59 kDecays/ml (= 3 s frame duration) to 59.2 MDecays/ml (= 1 h), allowed us to determine sets of parameters to achieve compliance with the current EARL 1 and EARL 2 standards. Recovery coefficients (RCs) were calculated for the metrics RCmax, RCmean, and RCpeak, and the respective recovery curves were analyzed for monotonicity. The background's coefficient of variation (COV) was also calculated. RESULTS Using 6 iterations, 5 subsets and 7.8 mm Gauss filtering resulted in optimal EARL1 compliance and recovery curve monotonicity in all analyzed frames, except in the 3 s frames. Most robust EARL2 compliance and monotonicity were achieved with 2 iterations, 5 subsets, and 3.6 mm Gauss FWHM in frames with durations between 30 s and 10 min. RCpeak only impeded EARL2 compliance in the 10 s and 3 s frames. CONCLUSIONS While EARL1 compliance was robust over most exposure ranges, EARL2 compliance required exposures between 1.2 MDecays/ml to 11.5 MDecays/ml. The Biograph Vision Quadra's high sensitivity makes frames as short as 10 s feasible for comparable quantitative images. Lowering EARL2 RCmax limits closer to unity would possibly even permit shorter frames

Non-Standard Errors

In statistics, samples are drawn from a population in a data generating process (DGP). Standard errors measure the uncertainty in sample 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. To study them, we let 164 teams test six hypotheses on the same sample. We find that non-standard errors are sizeable, on par with standard errors. Their size (i) co-varies only weakly with team merits, reproducibility, or peer rating, (ii) declines significantly after peer-feedback, and (iii) is underestimated by participants.Online appendix available at https://bit.ly/3DIQKrB.Please note a full list of authors is available in the working paper

Metabolic pathway and distribution of superparamagnetic iron oxide nanoparticles: in vivo study

Experimental tissue fusion benefits from the selective heating of superparamagnetic iron oxide nanoparticles (SPIONs) under high frequency irradiation. However, the metabolic pathways of SPIONs for tissue fusion remain unknown. Hence, the goal of this in vivo study was to analyze the distribution of SPIONs in different organs by means of magnetic resonance imaging (MRI) and histological analysis after a SPION-containing patch implantation