Duplication of the Hoxd11 gene causes alterations in the axial and appendicular skeleton of the mouse.

Journal ArticleThe Hox genes encode a group of transcription factors essential for proper development of the mouse. Targeted mutation of the Hoxd11 gene causes reduced male fertility, vertebral transformation, carpal bone fusions, and reductions in digit length. A duplication of the Hoxd11 gene was created with the expectation that the consequences of restricted overexpression in the appropriate cells would provide further insight into the function of the Hoxd11 gene product. Genetic assays demonstrated that two tandem copies of Hoxd11 were functionally indistinguishable from the normal two copies of the gene on separate chromosomes with respect to formation of the axial and appendicular skeleton. Extra copies of Hoxd11 caused an increase in the lengths of some bones of the forelimb autopod and a decrease in the number of lumbar vertebrae. Further, analysis of the Hoxd11 duplication demonstrated that the Hoxd11 protein can perform some functions supplied by its paralogue Hoxa11. For example, the defects in forelimb bones are corrected when extra copies of Hoxd11 are present in the Hoxa11 homozygous mutant background. Thus, it appears that Hoxd11 can quantitatively compensate for the absence of Hoxa11 protein, and therefore Hoxa11 and Hoxd11 are functionally equivalent in the zeugopod. However, extra copies of Hoxd11 did not improve male or female fertility in Hoxa11 mutants. Interestingly, the insertion of an additional Hoxd11 locus into the HoxD complex does not appear to affect the expression patterns of the neighboring Hoxd10, -d12, or -d13 genes

Effects on Calculated Half-Widths and Shifts from the Line Coupling for Asymmetric-Top Molecules

The refinement of the Robert-Bonamy formalism by considering the line coupling for linear molecules developed in our previous studies [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013); 140, 104304 (2014)] have been extended to asymmetric-top molecules. For H2O immersed in N2 bath, the line coupling selection rules applicable for the pure rotational band to determine whether two specified lines are coupled or not are established. Meanwhile, because the coupling strengths are determined by relative importance of off-diagonal matrix elements versus diagonal elements of the operator -iS1 -S2, quantitative tools are developed with which one is able to remove weakly coupled lines from consideration. By applying these tools, we have found that within reasonable tolerances, most of the H2O lines in the pure rotational band are not coupled. This reflects the fact that differences of energy levels of the H2O states are pretty large. But, there are several dozen strongly coupled lines and they can be categorized into different groups such that the line couplings occur only within the same groups. In practice, to identify those strongly coupled lines and to confine them into sub-linespaces are crucial steps in considering the line coupling. We have calculated half-widths and shifts for some groups, including the line coupling. Based on these calculations, one can conclude that for most of the H2O lines, it is unnecessary to consider the line coupling. However, for several dozens of lines, effects on the calculated half-widths from the line coupling are small, but remain noticeable and reductions of calculated half-widths due to including the line coupling could reach to 5%. Meanwhile, effects on the calculated shifts are very significant and variations of calculated shifts could be as large as 25%

Two dimensional symmetric correlation functions of the Ŝ operator and two dimensional Fourier transforms: Considering the line coupling for P and R lines of linear molecules

The refinement of the Robert-Bonamy (RB) formalism by considering the line coupling for isotropic Raman Q lines of linear molecules developed in our previous study [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)] has been extended to infrared P and R lines. In these calculations, the main task is to derive diagonal and off-diagonal matrix elements of the Liouville operator iS1 − S2 introduced in the formalism. When one considers the line coupling for isotropic Raman Q lines where their initial and final rotational quantum numbers are identical, the derivations of off-diagonal elements do not require extra correlation functions of the Ŝ operator and their Fourier transforms except for those used in deriving diagonal elements. In contrast, the derivations for infrared P and R lines become more difficult because they require a lot of new correlation functions and their Fourier transforms. By introducing two dimensional correlation functions labeled by two tensor ranks and making variable changes to become even functions, the derivations only require the latters’ two dimensional Fourier transforms evaluated at two modulation frequencies characterizing the averaged energy gap and the frequency detuning between the two coupled transitions. With the coordinate representation, it is easy to accurately derive these two dimensional correlation functions. Meanwhile, by using the sampling theory one is able to effectively evaluate their two dimensional Fourier transforms. Thus, the obstacles in considering the line coupling for P and R lines have been overcome. Numerical calculations have been carried out for the half-widths of both the isotropic Raman Q lines and the infrared P and R lines of C₂H₂ broadened by N₂. In comparison with values derived from the RB formalism, new calculated values are significantly reduced and become closer to measurements

Relaxation Matrix for Symmetric Tops with Inversion Symmetry: Line Coupling and Line Mixing Effects on NH3 Lines in the nu4 Band

Line shape parameters including the half-widths and the off-diagonal elements of the relaxation matrix have been calculated for self-broadened NH3 lines in the perpendicular nu4 band. As in the pure rotational and the parallel nu1 bands, the small inversion splitting in this band causes a complete failure of the isolated line approximation. As a result, one has to use formalisms not relying on this approximation. However, due to differences between parallel and perpendicular bands of NH3, the applicability of the formalism used in our previous studies of the nu1 band and other parallel bands must be carefully verified. We have found that, as long as potential models only contain components with K1 = K2 = 0, whose matrix elements require the selection rule ∆k = 0, the formalism is applicable for the nu4 band with some minor adjustments. Based on both theoretical considerations and results from numerical calculations, the non-diagonality of the relaxation matrices in all the PP, RP, PQ, RQ, PR, and RR branches is discussed. Theoretically calculated self-broadened half-widths are compared with measurements and the values listed in HITRAN 2012. With respect to line coupling effects, we have compared our calculated intra-doublet off-diagonal elements of the relaxation matrix with reliable measurements carried out in the PP branch where the spectral environment is favorable. The agreement is rather good since our results do well reproduce the observed k and j dependences of these elements, thus validating our formalism

Theoretical Studies of Spectroscopic Line Mixing in Remote Sensing Applications

The phenomenon of collisional transfer of intensity due to line mixing has an increasing importance for atmospheric monitoring. From a theoretical point of view, all relevant information about the collisional processes is contained in the relaxation matrix where the diagonal elements give half-widths and shifts, and the off-diagonal elements correspond to line interferences. For simple systems such as those consisting of diatom-atom or diatom-diatom, accurate fully quantum calculations based on interaction potentials are feasible. However, fully quantum calculations become unrealistic for more complex systems. On the other hand, the semi-classical Robert-Bonamy (RB) formalism, which has been widely used to calculate half-widths and shifts for decades, fails in calculating the off-diagonal matrix elements. As a result, in order to simulate atmospheric spectra where the effects from line mixing are important, semi-empirical fitting or scaling laws such as the ECS (Energy-Corrected Sudden) and IOS (Infinite-Order Sudden) models are commonly used. Recently, while scrutinizing the development of the RB formalism, we have found that these authors applied the isolated line approximation in their evaluating matrix elements of the Liouville scattering operator given in exponential form. Since the criterion of this assumption is so stringent, it is not valid for many systems of interest in atmospheric applications. Furthermore, it is this assumption that blocks the possibility to calculate the whole relaxation matrix at all. By eliminating this unjustified application, and accurately evaluating matrix elements of the exponential operators, we have developed a more capable formalism. With this new formalism, we are now able not only to reduce uncertainties for calculated half-widths and shifts, but also to remove a once insurmountable obstacle to calculate the whole relaxation matrix. This implies that we can address the line mixing with the semi-classical theory based on interaction potentials between molecular absorber and molecular perturber. We have applied this formalism to address the line mixing for Raman and infrared spectra of molecules such as N2, C2H2, CO2, NH3, and H2O. By carrying out rigorous calculations, our calculated relaxation matrices are in good agreement with both experimental data and results derived from the ECS model

International Medical Graduates in the Pediatric Workforce in the United States

Through the analysis of health workforce databases, in this study, we summarize the supply, distribution and characteristics of international medical graduates in the US pediatric workforce. BACKGROUND AND OBJECTIVES: To describe the supply, distribution, and characteristics of international medical graduates (IMGs) in pediatrics who provide patient care in the United States. METHODS: Cross-sectional study, combining data from the 2019 Physician Masterfile of the American Medical Association and the Educational Commission for Foreign Medical Graduates database. RESULTS: In total, 92 806 pediatric physicians were identified, comprising 9.4% of the entire US physician workforce. Over half are general pediatricians. IMGs account for 23.2% of all general pediatricians and pediatric subspecialists. Of all IMGs in pediatrics, 22.1% or 4775 are US citizens who obtained their medical degree outside the United States or Canada, and 15.4% (3246) attended medical school in the Caribbean. Fifteen non-US medical schools account for 29.9% of IMGs currently in active practice in pediatrics in the United States. IMGs are less likely to work in group practice or hospital-based practice and are more likely to be employed in solo practice (compared with US medical school graduates). CONCLUSIONS: With this study, we provide an overview of the pediatric workforce, quantifying the contribution of IMGs. Many IMGs are US citizens who attend medical school abroad and return to the United States for postgraduate training. Several factors, including the number of residency training positions, could affect future numbers of IMGs entering the United States. Longitudinal studies are needed to better understand the implications that workforce composition and distribution may have for the care of pediatric patients

A comparison of physician emigration from Africa to the United States of America between 2005 and 2015

BACKGROUND: Migration of health professionals has been a cause for global concern, in particular migration from African countries with a high disease burden and already fragile health systems. An estimated one fifth of African-born physicians are working in high-income countries. Lack of good data makes it difficult to determine what constitutes "African" physicians, as most studies do not distinguish between their country of citizenship and country of training. Thus, the real extent of migration from African countries to the United States (US) remains unclear. This paper quantifies where African migrant physicians come from, where they were educated, and how these trends have changed over time. METHODS: We combined data from the Educational Commission for Foreign Medical Graduates with the 2005 and 2015 American Medical Association Physician Masterfiles. Using a repeated cross-sectional study design, we reviewed the available data, including medical school attended, country of medical school, and citizenship when entering medical school. RESULTS: The outflow of African-educated physicians to the US has increased over the past 10 years, from 10 684 in 2005 to 13 584 in 2015 (27.1% increase). This represents 5.9% of all international medical graduates in the US workforce in 2015. The number of African-educated physicians who graduated from medical schools in sub-Saharan countries was 2014 in 2005 and 8150 in 2015 (304.6% increase). We found four distinct categorizations of African-trained physicians migrating to the US: (1) citizens from an African country who attended medical school in their own country (86.2%, n = 11,697); (2) citizens from an African country who attended medical school in another African country (2.3%, n = 317); (3) US citizens who attended medical school in an African country (4.0%, n = 537); (4) citizens from a country outside Africa, and other than the United States, who attended medical school in an African country (7.5%, n = 1013). Overall, six schools in Africa provided half of all African-educated physicians. CONCLUSIONS: The number of African-educated physicians in the US has increased over the past 10 years. We have distinguished four migration patterns, based on citizenship and country of medical school. The majority of African graduates come to the US from relatively few countries, and from a limited number of medical schools. A proportion are not citizens of the country where they attended medical school, highlighting the internationalization of medical education

Genesis and evolution of voçorocas on Botucatu formation rocks (Uper Araguaia river, Goiás and Mato Grosso states, Brazil).

Editors: Francisco Gutiérrez, Mateo Gutiérrez, Gloria Desir, Jesús Guerrero, Pedro Lucha, Cinta Marín, José María García-Ruiz