The link between regularity and strong-pi-regularity

It is shown that if all powers of a ring element $a$ are regular, then $a$ will be strongly-pi-regular exactly when a suitable word in the powers of $a$ and their inner inverses is a unit.Research with financial support provided by the Research Centre of Mathematics of the University of Minho (CMAT) through the FCT Pluriannual Funding Program

Testing strong line metallicity diagnostics at z~2

High-z galaxy gas-phase metallicities are usually determined through observations of strong optical emission lines with calibrations tied to the local universe. Recent debate has questioned if these calibrations are valid in the high-z universe. We investigate this by analysing a sample of 16 galaxies at z~2 available in the literature, and for which the metallicity can be robustly determined using oxygen auroral lines. The sample spans a redshift range of 1.4 < z < 3.6, has metallicities of 7.4-8.4 in 12+log(O/H) and stellar masses 10^7.5-10^11 Msun. We test commonly used strong line diagnostics (R23, O3, O2, O32, N2, O3N2 and Ne3O2 ) as prescribed by four different sets of empirical calibrations, as well as one fully theoretical calibration. We find that none of the strong line diagnostics (or calibration set) tested perform consistently better than the others. Amongst the line ratios tested, R23 and O3 deliver the best results, with accuracies as good as 0.01-0.04 dex and dispersions of ~0.2 dex in two of the calibrations tested. Generally, line ratios involving nitrogen predict higher values of metallicity, while results with O32 and Ne3O2 show large dispersions. The theoretical calibration yields an accuracy of 0.06 dex, comparable to the best strong line methods. We conclude that, within the metallicity range tested in this work, the locally calibrated diagnostics can still be reliably applied at z~2.Comment: 12 pages, 8 Figures, accepted for publication in MNRA

Diagonalizing triangular matrices via orthogonal Pierce decompositions

A class of sufficient conditions is given to ensure that the sum a+b in a ring R, is equivalent to a sum x + y, which is an orthogonal Pierce decomposition. This is then used to show that a lower triangular matrix, with a regular diagonal is equivalent to its diagonal iff the matrix admits a lower triangular von Neumann inverse.Fundação para a Ciência e a Tecnologia (FCT) – Programa Operacional “Ciência, Tecnologia, Inovação” (POCTI)

Control of Ralstonia solanacearum in tomato potting medium by the use of a solar collector.

A solar collector was used to disinfest potting medium inoculated with Ralstonia solanacearum. Tomato plantlets grown in the potting medium treated in the solar collector for one full day had no symptoms of bacterial wilt

Repeated assessment and practice effects of the written symbol digit modalities test using a short inter-test interval

The Symbol Digit Modalities Test (SDMT) is a widely used instrument to assess information processing speed, attention, visual scanning, and tracking. Considering that repeated evaluations are a common need in neuropsychological assessment routines, we explored test–retest reliability and practice effects of two alternate SDMT forms with a short inter-assessment interval. A total of 123 university students completed the written SDMT version in two different time points separated by a 150-min interval. Half of the participants accomplished the same form in both occasions, while the other half filled different forms. Overall, reasonable test–retest reliabilities were found (r = .70), and the subjects that completed the same form revealed significant practice effects (p < .001, dz = 1.61), which were almost non-existent in those filling different forms. These forms were found to be moderately reliable and to elicit a similar performance across participants, suggesting their utility in repeated cognitive assessments when brief inter-assessment intervals are required.This work was supported by European Union FEDER funds through Programa Operacional Factores de Competitividade (COMPETE) for ADI Project "DoIT-Desenvolvimento e Operacionalizacao da Investigacao de Translacao" ("MyHealth-PPS4"; project no 13853)

Scaling of the elastic contribution to the surface free energy of a nematic on a sawtoothed substrate

We characterize the elastic contribution to the surface free energy of a nematic in presence of a sawtooth substrate. Our findings are based on numerical minimization of the Landau-de Gennes model and analytical calculations on the Frank-Oseen theory. The nucleation of disclination lines (characterized by non-half-integer winding numbers) in the wedges and apexes of the substrate induces a leading order proportional to qlnq to the elastic contribution to the surface free energy density, q being the wavenumber associated with the substrate periodicity.Comment: 7 pages, 6 figures, accepted for publication in Physical Review

Not All Pseudoaneurysms Are Femoral. A Transcaval Transcatheter Aortic Valve Replacement Rare Complication

We report a case of a 73-year-old male with multiple comorbidities, including postpoliomyelitis severe scoliosis, referred to our tertiary center due to a severe symptomatic aortic stenosis, considered high risk for surgical aortic valve replacement (AVR). Due to unsuitable femoral and subclavian accesses, the patient underwent a transcaval transcatheter AVR (TAVR) procedure, complicated by the development of an iatrogenic infrarenal aortic pseudoaneurysm with aortocaval fistula. Scoliosis can cause varying anatomic relationships between retroperitoneal vessels and intervertebral disk spaces, which increase the difficulty of the procedure and consequently lead to this vascular complication. Although most aortocaval fistulas close spontaneously after 1 year, the risk of pseudoaneurysm rupture in this critical area was crucial in the decision of a new successful percutaneous aortic stent intervention.info:eu-repo/semantics/publishedVersio

Project management in the development of dynamic capabilities for an open innovation era

The aim of the research is to explain how Project Management (PM) ensures the accumulation, integration, utilization, and reconfiguration of the capabilities and knowledge acquired in projects in order to build dynamic capabilities (DCs). This study also gives insight into how PM can develop DCs through the identification and implementation of project management opportunities. The result of 22 semi-structured interviews with 22 participants from 9 companies of different industries are detailed and framed within theoretical dimensions of DCs: knowledge accumulation, integration, utilization, reconfiguration, sensing, and seizing. As a result, we present the best practices, techniques, and PM tools that allow leveraging DCs in organizations. This qualitative study contributes to a theoretical and empirical discussion about how PM transforms knowledge acquired in projects into routines and learning practices that allow organizations to develop or reshape capabilities.info:eu-repo/semantics/publishedVersio

The multi-compartment si(Rd) model with regime switching: An application to covid-19 pandemic

Grant No. 19-01-00451 UID/MAT/00297/2020We study—with existence and unicity results—a variant of the SIR model for an infectious disease incorporating both the possibility of a death outcome—in a short period of time—and a regime switch that can account for the mitigation measures used to control the spreading of the infections, such as a total lockdown. This model is parametrised by three parameters: the basic reproduction number, the mortality rate of the infected, and the duration of the disease. We discuss a particular example of application to Portuguese COVID-19 data in two short periods just after the start of the epidemic in 4 March 2020, with the first two cases dated that day. We propose a simple and effective method for the estimation of the main parameters of the disease, namely, the basic reproduction number and the mortality rate of the infected. We correct these estimated values to take into account the asymptomatic non-diagnosed members of the population. We compare the outcome of the model in the cases of the existence, or not, of a regime switch, and under three different scenarios, with a remarkable agreement between model and data deaths in the case of our basis scenario. In a final short remark, we deal with the existence of symmetries for the proposed model.publishersversionpublishe

Impact of Obesity on Results after Primary Angioplasty in Patients with ST Segment Elevation Acute Myocardial Infarction

INTRODUCTION: Obesity is an important risk factor for the development of diabetes, hypertension, coronary disease, left ventricular dysfunction, stroke and cardiac arrhythmias. Paradoxically, previous studies in patients undergoing elective coronary angioplasty showed a reduction in hospital and long-term mortality in obese patients. The relation with body mass index (BMI) has been less studied in the context of primary angioplasty. OBJECTIVES: To evaluate the impact of obesity on the results of ST-segment elevation acute myocardial infarction treated by primary angioplasty. METHODS: This was a study of 464 consecutive patients with ST-segment elevation acute myocardial infarction undergoing primary angioplasty, 78% male, mean age 61 +/- 13 years. We assessed in-hospital, 30-day and one-year mortality according to BMI. Patients were divided into three groups according to BMI: normal--18-24.9 kg/m2 (n = 171); overweight--25-29.9 kg/m2 (n = 204); and obese-- > 30 kg/m2 (n = 89). RESULTS: Obese patients were younger (ANOVA, p < 0.001) and more frequently male (p = 0.014), with more hypertension (p = 0.001) and dyslipidemia (p = 0.006). There were no differences in the prevalence of diabetes, previous cardiac history, heart failure on admission, anterior location, multivessel disease, peak total CK or medication prescribed, except that obese patients received more beta-blockers (p = 0.049). In-hospital mortality was 9.9% for patients with normal BMI, 3.4% for overweight patients and 6.7% for obese patients (p = 0.038). Mortality at 30 days was 11 4.4% and 7.8% (p = 0.032) and at one year 12.9%, 4.9% and 9% (p = 0.023), respectively. On univariate analysis, overweight was the only BMI category with a protective effect; however, after multivariate logistic regression analysis, adjusted for confounding variables, none of the BMI categories could independently predict outcome. CONCLUSIONS: Overweight patients had a better prognosis after primary angioplasty for ST-segment elevation acute myocardial infarction compared with other BMI categories, but this was dependent on other potentially confounding variables