Rossby waves and α\alpha-effect

Rossby waves drifting in the azimuthal direction are a common feature at the onset of thermal convective instability in a rapidly rotating spherical shell. They can also result from the destabilization of a Stewartson shear layer produced by differential rotation as expected in the liquid sodium experiment (DTS) working in Grenoble, France. A usual way to explain why Rossby waves can participate to the dynamo process goes back to Busse (1975). In his picture, the flow geometry is a cylindrical array of parallel rolls aligned with the rotation axis. The axial flow component (the component parallel to the rotation axis) is (i) maximum in the middle of each roll and changes its sign from one roll to the next. It is produced by the Ekman pumping at the fluid containing shell boundary. The corresponding dynamo mechanism can be explained in terms of an $\alpha$-tensor with non-zero coefficients on the diagonal. In rapidly rotating objects like the Earth's core (or in a fast rotating experiment), Rossby waves occur in the limit of small Ekman number ($\approx 10^{-15}$). In that case, the main source of the axial flow component is not the Ekman pumping but rather the ``geometrical slope effect'' due to the spherical shape of the fluid containing shell. This implies that the axial flow component is (ii) maximum at the borders of the rolls and not at the centers. If assumed to be stationary, such rolls would lead to zero coefficients on the diagonal of the $\alpha$-tensor, making the dynamo probably less efficient if possible at all. Actually, the rolls are drifting as a wave, and we show that this drift implies non--zero coefficients on the diagonal of the $\alpha$-tensor. These new coefficients are in essence very different from the ones obtained in case (i) and cannot be interpreted in terms of the heuristic picture of Busse (1975)

My COVID-19 Experience

Student generated description: “Artwork of a Makeup Palette I designed based on COVID-19 and my experience

Enhancing academic achievement and satisfaction by flipping the teacher preparation classroom

This study compared flipped classrooms versus online courses to study the effects of the two instructional methodologies on student achievement and satisfaction in an undergraduate Introduction to Education, EDUC 1301, course. Students self-matriculated in either traditional EDUC 1301 courses which were flipped or in EDUC 1301 online courses. Students\u27 final grades were used to assess student achievement in both teaching methodologies. An end-of-course student evaluation of instructor performance was used to assess students\u27 satisfaction in the courses. A casual comparative research design was used to examine the effectiveness of both teaching methodologies. There was no differences between the two instructional methodologies in student satisfaction. Students were equally satisfied in both teaching methodologies. Statistical significant differences were found, however, in the students\u27 achievement level. The percent of students in the flipped classroom who passed the courses was 92% compared with 75% achievement level in the students who passed the online courses. The number of students who passed the EDUC 1301 flipped classroom courses as presented in Table 1, page 44, and Figure 1, page 44, was 83 out of 90, resulting in an achievement level of 92%. On the contrary, 118 out of 157 students passed the EDUC 1301 online courses, as shown in Table 1, page 44, and Figure 1, page 44, representing an achievement level of 75%. The Pearson chi-square test of association yielded a chi2 of 10.99, a df = 1, and a p value of 0.0001 which was statistically significant at the 95% confidence level (p \u3c .05), Table 3, page 45. Students who self-enrolled in the flipped classrooms did statistically significantly better than those students who self-enrolled in the online courses. Instructional methodology, however, was an insignificant predictor of student satisfaction between the students in the flipped classrooms and the online courses. (PsycInfo Database Record (c) 2022 APA, all rights reserved

MECHANISTIC STUDY OF A RUTHENIUM HYDRIDE COMPLEX OF TYPE [RuH(CO)(N-N)(PR3)2]+ AS CATALYST PRECURSOR FOR THE HYDROFORMYLATION REACTION OF 1-HEXENE

Indexación: Web of Science; Scopus; Scielo.The catalytic activity of systems of type [RuH(CO)(N-N)(PR3)(2)](+) was evaluated in the hydroformylation reaction of 1-hexene. The observed activity is explained through a reaction mechanism on the basis of the quantum theory. The mechanism included total energy calculations for each of the intermediaries of the elemental steps considered in the catalytic cycle. The deactivation of the catalyst precursors takes place via dissociation of the polypyridine ligand and the subsequent formation of thermodynamically stable species, such as RuH(CO)(3)(PPh3)(2) and RuH3(CO)(PPh3)(2), which interrupt the catalytic cycle. In addition, the theoretical study allows to explain the observed regioselectivity which is defined in two steps: (a) the hydride migration reaction with an anti-Markovnikov orientation to produce the alkyl-linear-complex (3.1a), which is more stable by 19.4 kJ/mol than the Markovnikov orientation (alkyl-branched-complex) (3.1b); (b) the carbon monoxide insertion step generates the carbonyl alkyl-linear specie (4.1a) which is more stable by 9.5 kJ/mol than the alternative species (4.1b), determining the preferred formation of heptanal in the hydroformylation of 1-hexene. Palabras clavehttp://ref.scielo.org/db4yc

Nevirapine- and efavirenz-associated hepatotoxicity under programmatic conditions in Kenya and Mozambique.

To describe the frequency, risk factors, and clinical signs and symptoms associated with hepatotoxicity (HT) in patients on nevirapine- or efavirenz-based antiretroviral therapy (ART), we conducted a retrospective cohort analysis of patients attending the ART clinic in Kibera, Kenya, from April 2003 to December 2006 and in Mavalane, Mozambique, from December 2002 to March 2007. Data were collected on 5832 HIV-positive individuals who had initiated nevirapine- or efavirenz-based ART. Median baseline CD4+ count was 125 cells/μL (interquartile range [IQR] 55-196). Over a median follow-up time of 426 (IQR 147-693) days, 124 (2.4%) patients developed HT. Forty-one (54.7%) of 75 patients with grade 3 HT compared with 21 (80.8%) of 26 with grade 4 had associated clinical signs or symptoms (P = 0.018). Four (5.7%) of 124 patients with HT died in the first six months compared with 271 (5.3%) of 5159 patients who did not develop HT (P = 0.315). The proportion of patients developing HT was low and HT was not associated with increased mortality. Clinical signs and symptoms identified 50% of grade 3 HT and most cases of grade 4 HT. This suggests that in settings where alanine aminotransferase measurement is not feasible, nevirapine- and efavirenz-based ART may be given safely without laboratory monitoring

Inferior alveolar and lingual nerve injuries: An overview of diagnosis and management

Oral and maxillofacial surgery operations are susceptible to cause injury to terminal branches of the trigeminal nerve. The mandibular division is more prone to injury than ophthalmic and maxillary nerves. Inferior alveolar branch of the trigeminal nerve is the most commonly injured branch, followed by the lingual nerve. These nerves may be subjected to neurosensorial disturbance during third molar surgery, followed by sagittal split ramus osteotomy, endodontic therapy and dental implant placement. Local anesthetic injections, pre-prosthetic surgery, various other types of orthognathic surgery, ablative tumor surgery involving mandibular resections, osteoradionecrosis, osteomyelitis or maxillofacial trauma are among other potential etiologic factors. If an inferior alveolar or lingual nerve injury occurs, a timely diagnosis and a proper management are key factors to avoid further or permanent damage. A wide range of therapeutic modalities are available in managing nerve injuries, ranging from simple observation to complex grafting, depending on various factors. Data regarding nerve injuries may not always be reliable since most are based upon personal experience and in a retrospective nature. It is also challenging to draw proper conclusions from studies on nerve injuries due to the differences in outcome criteria and assessment methods. Still, an accurate knowledge of anatomy should be combined with both clinical and radiological data to avoid any nerve-related complications. Thus, this article will present a narrative review of the current literature on the inferior alveolar and lingual nerve injuries, focusing on the functional assessment methods, factors influencing recovery, the contemporary management protocols as well as future trends in nerve repairs

Pylephlebitis: An Uncommon Complication of Intra-Abdominal Infection

<p>We herein present a case of pylephlebitis, which is an infective suppurative thrombosis of the portal vein. Pylephlebitis is an uncommon complication of intra-abdominal infections and carries with it significant morbidity and mortality. [West J Emerg Med. 2011;12(4):575–576.]</p

Healthcare satisfaction in lung cancer survivors: A cross-sectional secondary data analytic study

Introduction: Lung cancer is commonly associated with high levels of psychosocial distress and symptom burden. Healthcare professionals endeavor to meet complex needs, yet current research is sparse and presents an inconsistent picture of predictors of healthcare satisfaction in lung cancer. We examined psychosocial, physical functioning, demographic, and supportive care factors as predictors of healthcare satisfaction in a sample of lung cancer survivors. Method: We conducted a cross-sectional secondary data analysis to examine psychosocial functioning, physical functioning, supportive care needs, healthcare satisfaction, and demographic and medical characteristics in lung cancer survivors sampled from two southern California hospitals (N = 187). Mean difference tests and Pearson correlations were utilized prior to entering significant predictors into a hierarchical regression model predicting healthcare satisfaction. Results: A hierarchical regression model indicated that greater information needs (beta = -.43, p \u3c .001), greater psychological needs (beta = -.18, p \u3c .04), and more time since diagnosis of lung cancer (beta = -.13, p \u3c .05) independently predicted a lower levels of healthcare satisfaction. Conclusions: Clinicians working with lung cancer survivors are encouraged to assess for unmet supportive care needs at regular intervals. It is unclear whether demographic characteristics that were predictive of healthcare satisfaction in other studies (e.g., ethnic background) were not found in our study due to characteristics of the healthcare settings for our sample or possibly the cross-sectional nature of our study. Future research may expand on our findings by examining predictors of healthcare satisfaction in longitudinal studies

A photogrammetric solution to a particular problem

A closed-form mathematical solution to the classical photogrammetric problem is presented. Although quite general, the solution is more applicable to problems in which the image-space conjugates are very difficult to match but one of the elements of the pair is not. Additionally, observations are made that should make the solution to the general problem of automatic matching less computationally intensive. This approach was used to analyze flow visualization data for the F-18 High Alpha Research Vehicle. The conditions for this analysis were less than ideal for image-to-object-space transformation