Washington Meets Wall Street: A Closer Examination of the Presidential Cycle Puzzle

This paper tests the policitcal dimensions of the presidential cycle effect in U.S. financial markets. The presidential cycle effect states that average stock market returns are significantly higher in the last two years compared to the first two years of a presidential term. We confirm the robust existence of this cycle in U.S. stock markets as well as bond markets. As most rational theories to explain the cycle were falsified by earlier empirical work, this paper sets out to test the presidential cycle election (PCE) theory as an alternative explanation. The PCE theory states that incumbent parties and presidents have an incentive to manipulate the economy (via budget expansions, taxes, etc.) to remain in power. We formulate seven different propositions relating to fiscal, monetary, tax, and political implications of PCE theory. We find no statistically significant evidence confirming the PCE theory as a plausible explanation for the presidential cycle effect. The existence of the presidential cycle effect in U.S. financial markets thus remains a puzzle that cannot be easily explained by politicians mis-using their economic influence to remain in power

Irrigant flow in the root canal during ultrasonic activation:A numerical fluid-structure interaction model and its validation

Aim: The aim of the study was (a) to develop a three-dimensional numerical model combining the oscillation of a tapered ultrasonic file and the induced irrigant flow along with their two-way interaction in the confinement of a root canal. (b) To validate this model through comparison with experiments and theoretical (analytical) solutions of the flow. Methodology: Two partial numerical models, one for the oscillation of the ultrasonic file and another one for the irrigant flow inside the root canal around the file, were created and coupled in order to take into account the two-way coupled fluid–structure interaction. Simulations were carried out for ultrasonic K-files and for smooth wires driven at four different amplitudes in air or inside an irrigant-filled straight root canal. The oscillation pattern of the K-files was determined experimentally by Scanning Laser Vibrometry, and the flow pattern inside an artificial root canal was analysed using high-speed imaging together with Particle Image Velocimetry. Analytical solutions were obtained from an earlier study. Numerical, experimental and analytical results were compared to assess the validity of the model. Results: The comparison of the oscillation amplitude and node location of the ultrasonic files and of the irrigant flow field showed a close agreement between the simulations, experiments and theoretical solutions. Conclusions: The model is able to predict reliably the file oscillation and irrigant flow inside root canals during ultrasonic activation under similar conditions

Washington meets Wall Street: a closer examination of the presidential cycle puzzle

We show that average excess returns during the last two years of the presidential cycle are significantly higher than during the first two years: 9.8 percent over the period 1948 – 2008. This pattern in returns cannot be explained by business-cycle variables capturing time-varying risk premia, differences in risk levels, or by consumer and investor sentiment. In this paper, we formally test the presidential election cycle (PEC) hypothesis as the alternative explanation found in the literature for explaining the presidential cycle anomaly. PEC states that incumbent parties and presidents have an incentive to manipulate the economy (via budget expansions and taxes) to remain in power. We formulate eight empirically testable propositions relating to the fiscal, monetary, tax, unexpected inflation and political implications of the PEC hypothesis. We do not find statistically significant evidence confirming the PEC hypothesis as a plausible explanation for the presidential cycle effect. The existence of the presidential cycle effect in U.S. financial markets thus remains a puzzle that cannot be easily explained by politicians employing their economic influence to remain in power. JEL Classification: E32; G14; P16 Keywords: Political Economy, Market Efficiency, Anomalies, Calendar Effect

Prescription of the first prosthesis and later use in children with congenital unilateral upper limb deficiency: A systematic review

Background: The prosthetic rejection rates in children with an upper limb transversal reduction deficiency are considerable. It is unclear whether the timing of the first prescription of the prosthesis contributes to the rejection rates. Objective: To reveal whether scientific evidence is available in literature to confirm the hypothesis that the first prosthesis of children with an upper limb deficiency should be prescribed before two years of age. We expect lower rejection rates and better functional outcomes in children fitted at young age. Methods: A computerized search was performed in several databases (Medline, Embase, Cinahl, Amed, Psycinfo, PiCarta and the Cochrane database). A combination of the following keywords and their synonyms was used: "prostheses, upper limb, upper extremity, arm and congenital''. Furthermore, references of conference reports, references of most relevant studies, citations of most relevant studies and related articles were checked for relevancy. Results: The search yielded 285 publications, of which four studies met the selection criteria. The methodological quality of the studies was low. All studies showed a trend of lower rejection rates in children who were provided with their first prosthesis at less than two years of age. The pooled odds ratio of two studies showed a higher rejection rate in children who were fitted over two years of age ( pooled OR 3.6, 95% CI 1.6-8.0). No scientific evidence was found concerning the relation between the age at which a prosthesis was prescribed for the first time and functional outcomes. Conclusion: In literature only little evidence was found for a relationship between the fitting of a first prosthesis in children with a congenital upper limb deficiency and rejection rates or functional outcomes. As such, clinical practice of the introduction of a prosthesis is guided by clinical experience rather than by evidence-based medicine

The response of dual-species bacterial biofilm to 2% and 5% NaOCl mixed with etidronic acid:A laboratory real-time evaluation using optical coherence tomography

Aim: The addition of etidronic acid (HEDP) to sodium hypochlorite (NaOCl) could increase the antibiofilm potency of the irrigant, whilst maintaining the benefits of continuous chelation. Studies conducted so far have shown that mixing HEDP with NaOCl solutions of relatively low concentration does not compromise the antibiofilm efficacy of the irrigant. However, the working lifespan of NaOCl may decrease resulting in a reduction of its antibiofilm efficacy over time (efficiency). In this regard, continuous irrigant replenishment needs to be examined. This study investigated the response of a dual-species biofilm when challenged with 2% and 5% NaOCl mixed with HEDP for a prolonged timespan and under steady laminar flow. Methodology: Dual-species biofilms comprised of Streptococcus oralis J22 and Actinomyces naeslundii T14V-J1 were grown on human dentine discs in a constant depth film fermenter (CDFF) for 96 h. Biofilms were treated with 2% and 5% NaOCl, alone or mixed with HEDP. Irrigants were applied under steady laminar flow for 8 min. Biofilm response was evaluated by means of optical coherence tomography (OCT). Biofilm removal, biofilm disruption, rate of biofilm loss and disruption as well as bubble formation were assessed. One-way anova, Wilcoxon's signed-rank test and Kruskal–Wallis H test were performed for statistical analysis of the data. The level of significance was set at a ≤.05. Results: Increasing NaOCl concentration resulted in increased biofilm removal and disruption, higher rate of biofilm loss and disruption and increased bubble formation. Mixing HEDP with NaOCl caused a delay in the antibiofilm action of the latter, without compromising its antibiofilm efficacy. Conclusions: NaOCl concentration dictates the biofilm response irrespective of the presence of HEDP. The addition of HEDP resulted in a delay in the antibiofilm action of NaOCl. This delay affects the efficiency, but not the efficacy of the irrigant over time

Cost analysis of robot-assisted versus open transthoracic esophagectomy for resectable esophageal cancer. Results of the ROBOT randomized clinical trial

Background: The previously published ROBOT trial demonstrated that robot assisted minimally invasive esophagectomy (RAMIE) is associated with a lower percentage of postoperative complications compared to open esophagectomy (OTE) for patients with esophageal cancer. The implications of these results on healthcare costs are important given the increased attention for cost-reduction in healthcare. Therefore the aim of this study was to report the hospital costs of RAMIE compared to OTE as treatment for esophageal cancer. Methods: The ROBOT trial randomized 112 patients with esophageal cancer between RAMIE and OTE through January 2012 and August 2016 in a single tertiary care academic centre in the Netherlands. The primary outcome of the current study was hospital costs from the day of esophagectomy until 90 days after discharge based on Time-Driven Activity-Based Costing methodology. Secondary outcomes included the incremental cost-effectiveness ratio per complication prevented and risk factors for increased hospital costs. Results: Of the 112 included patients, 109 patients underwent an esophagectomy, of whom 54 RAMIE and 55 OTE. The mean total hospital costs were comparable between RAMIE €40211 and OTE €39495 (mean difference €-715; bias-corrected and accelerated confidence interval € −14831 to 14783, p = 0.932). At a willingness-to-pay threshold of €20.000 to €25.000 (i.e. estimated additional costs to the hospital to treat patients with a complication) RAMIE had a probability 62%–70% of being cost effective to prevent postoperative complications. In multivariable regression analysis, major postoperative complications were the main driver of hospital costs after esophagectomy (€31839, p = 0.009). Conclusion: In this randomized trial RAMIE resulted in fewer postoperative complications compared to OTE without increasing total hospital costs

Effect of fixed orthodontic appliances on salivary microbial parameters at 6 months:a controlled observational study

Objective: The aim of this study was to assess the microbial changes in children with fixed orthodontic appliances compared with a control group of children without orthodontic treatment. Material and Methods: Ninety-five children, aged between 12 and 16 years, participated in this study. Forty-eight subjects were fitted with fixed orthodontic appliances and forty-seven were free of any such appliances. The follow-up was 6 months for all children. The association between orthodontic appliances and high levels of Streptococcus mutans and Lactobacillus spp was assessed with logistic regression models, taking age, sex, pH and buffer capacity into account. Results: Differences at baseline between the two groups were not statistically significant. We found that wearing a fixed orthodontic appliance was associated with high levels of Streptococcus mutans and Lactobacillus spp (adjusted OR: 6.65, 95% CI [1.98-22.37]; 9.49, 95% CI [2.57-35.07], respectively), independently of other variables. Conclusion: The originality of the present epidemiological study was to evaluate the evolution of salivary microbial parameters in a population of children with fixed orthodontic appliances. Our results show an increase of Streptococcus mutans and Lactobacillus spp values during the follow-up. The whole dental workforce should be aware that preventive measures are of paramount importance during orthodontic treatment

Bis-picolinamide Ruthenium(III) Dihalide Complexes: Dichloride-to-Diiodide Exchange Generates Single trans Isomers with High Potency and Cancer Cell Selectivity

A library of new bis-picolinamide ruthenium(III) dihalide complexes of the type [RuX2L2] (X=Cl or I, L=picolinamide) have been synthesised and characterised. The complexes exhibit different picolinamide ligand binding modes, whereby one ligand is bound (N,N) and the other bound (N,O). Structural studies revealed a mixture of cis and trans isomers for the [RuCl2L2] complexes but upon a halide exchange reaction to yield [RuI2L2], only single trans isomers were detected. High cytotoxic activity against human cancer cell lines was observed, with the potencies of some complexes similar to or better than cisplatin. The conversion to [RuI2L2] substantially increased the activity towards cancer cell lines by more than twelvefold. The [RuI2L2] complexes displayed potent activity against the A2780cis (cisplatin-resistant human ovarian cancer) cell line, with a more than fourfold higher potency than cisplatin. Equitoxic activity was observed against normoxic and hypoxic cancer cells, which indicates the potential to eradicate both the hypoxic and aerobic fractions of solid tumours with similar efficiency. The activity of selected complexes against non-cancer ARPE-19 cells was also tested. The [RuI2L2] complexes were found to be more potent than the [RuCl2L2] analogues and also more selective towards cancer cells with a selectivity factor in excess of sevenfold