604 research outputs found

    Helping Babies Survive Training Programs: Evaluating a Teaching Cascade in Ethiopia

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    Background: 2.6 million neonates die annually; the vast majority of deaths occur in low- and middle-income countries (LMICs). The Helping Babies Survive (HBS) programs are commonly used in LMICs to reduce neonatal mortality through education. They are typically disseminated using a train-the-trainer cascade. However, there is little published literature on the extent and cost of dissemination. In 2015, the Ethiopian Ministry of Health and partner organizations implemented a countrywide HBS training cascade for midwives in 169 hospitals.Methods: We quantified the extent of HBS dissemination, and characterized barriers that impeded successful hospital-based training by surveying a representative from each of the 169 participant hospitals. This occurred from September 2017 to April 2018. We also assessed the cost of the training cascade. To assess acquisition of knowledge and skill in the training cascade, multiple-choice question examinations (MCQE) and objective structured clinical evaluations (OSCE) were conducted.Results: Hospital-based training occurred in 132 participant hospitals (78%). 1,146 midwives, 69% of those employed by participant hospitals, received hospital-based training. Barriers included lack of preparation of hospital-based educators and limited logistical support. The cascade cost an average of 2,105 USD per facility or 197 USD per trainee. Knowledge improved and skills were adequate for regional workshop attendees based on MCQE and OSCE performance.Conclusion: The train-the-trainer strategy is an effective and affordable strategy for widespread dissemination of the HBS programs in LMICs. Future studies should assess knowledge and skill acquisition following the variety of pragmatic training approaches that may be employed at the facility-level

    Measurement of interfacial tension of immiscible liquid pairs in microgravity

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    A discussion is given of a containerless microgravity experiment aimed at measuring the interfacial tension of immiscible liquid pairs using a compound drop rotation method. The reasons for the failure to execute such experiments in microgravity are described. Also, the results of post-flight analyses used to confirm our arguments are presented

    Spin Path Integrals and Generations

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    The spin of a free electron is stable but its position is not. Recent quantum information research by G. Svetlichny, J. Tolar, and G. Chadzitaskos have shown that the Feynman \emph{position} path integral can be mathematically defined as a product of incompatible states; that is, as a product of mutually unbiased bases (MUBs). Since the more common use of MUBs is in finite dimensional Hilbert spaces, this raises the question "what happens when \emph{spin} path integrals are computed over products of MUBs?" Such an assumption makes spin no longer stable. We show that the usual spin-1/2 is obtained in the long-time limit in three orthogonal solutions that we associate with the three elementary particle generations. We give applications to the masses of the elementary leptons.Comment: 20 pages, 2 figures, accepted at Foundations of Physic

    Electromagnetic Corrections to Pi Pi Scattering: Some Lessons for the Implementation of Meson Exchange Models

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    The leading non-Coulombic electromagnetic contributions to pi pi s-wave scattering lengths are computed in Chiral Perturbation Theory. It is shown that these corrections are zeroth order in the chiral expansion and associated with electromagnetic contact terms in the effective Lagrangian, i.e. that they do not involve explicit photon fields in the low-energy effective theory. It is pointed out that, if one followed the standard meson-exchange-model ansatz for removing electromagnetic effects, i.e. of subtracting contributions associated with explicit photon exchange and radiative corrections, as determined by the photon coupling vertices of the effective hadronic theory, one would completely miss these contributions and arrive at the erroneous conclusion that the strong interactions exhibited very large isospin breaking in pi pi scattering. Implications for electromagnetic "subtraction" procedures in other hadronic systems and the utility of the effective Lagrangian method for avoiding such errors are obvious.Comment: 16 pages, REVTE

    PT-Symmetric Quantum Electrodynamics

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    The Hamiltonian for quantum electrodynamics becomes non-Hermitian if the unrenormalized electric charge ee is taken to be imaginary. However, if one also specifies that the potential AμA^\mu in such a theory transforms as a pseudovector rather than a vector, then the Hamiltonian becomes PT symmetric. The resulting non-Hermitian theory of electrodynamics is the analog of a spinless quantum field theory in which a pseudoscalar field ϕ\phi has a cubic self-interaction of the form iϕ3i\phi^3. The Hamiltonian for this cubic scalar field theory has a positive spectrum, and it has recently been demonstrated that the time evolution of this theory is unitary. The proof of unitarity requires the construction of a new operator called C, which is then used to define an inner product with respect to which the Hamiltonian is self-adjoint. In this paper the corresponding C operator for non-Hermitian quantum electrodynamics is constructed perturbatively. This construction demonstrates the unitarity of the theory. Non-Hermitian quantum electrodynamics is a particularly interesting quantum field theory model because it is asymptotically free.Comment: 9 pages, no figures, revtex

    New Approach to Quantum Field Theory for Arbitrary Observers in Electromagnetic Backgrounds

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    A reformulation of fermionic QFT in electromagnetic backgrounds is presented which uses methods analogous to those of conventional multiparticle quantum mechanics. Emphasis is placed on the (Schr\"odinger picture) states of the system, described in terms of Slater determinants of Dirac states, and not on the field operator ψ^(x)\hat{\psi}(x) (which is superfluous in this approach). The vacuum state `at time τ\tau' is defined as the Slater determinant of a basis for the span of the negative spectrum of the `first quantized' Hamiltonian H^(τ)\hat{H}(\tau), thus providing a concrete realisation of the Dirac Sea. The general S-matrix element of the theory is derived in terms of time-dependent Bogoliubov coefficients, demonstrating that the S-matrix follows directly from the definition of inner product between Slater determinants. The process of `Hermitian extension', inherited directly from conventional multiparticle quantum mechanics, allows second quantized operators to be defined without appealing to a complete set of orthonormal modes, and provides an extremely straightforward derivation of the general expectation value of the theory. The concept of `radar time', advocated by Bondi in his work on k-calculus, is used to generalise the particle interpretation to an arbitrarily moving observer. A definition of particle results, which depends {\it only} on the observer's motion and the background present, not on any choice of coordinates or gauge, or of the particle detector. We relate this approach to conventional methods by comparing and contrasting various derivations. Our particle definition can be viewed as a generalisation to arbitrary observers of Gibbons' approach.Comment: 36 pages, 3 figure

    Angular Conditions,Relations between Breit and Light-Front Frames, and Subleading Power Corrections

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    We analyze the current matrix elements in the general collinear (Breit) frames and find the relation between the ordinary (or canonical) helicity amplitudes and the light-front helicity amplitudes. Using the conservation of angular momentum, we derive a general angular condition which should be satisfied by the light-front helicity amplitudes for any spin system. In addition, we obtain the light-front parity and time-reversal relations for the light-front helicity amplitudes. Applying these relations to the spin-1 form factor analysis, we note that the general angular condition relating the five helicity amplitudes is reduced to the usual angular condition relating the four helicity amplitudes due to the light-front time-reversal condition. We make some comments on the consequences of the angular condition for the analysis of the high-Q2Q^2 deuteron electromagnetic form factors, and we further apply the general angular condition to the electromagnetic transition between spin-1/2 and spin-3/2 systems and find a relation useful for the analysis of the N-Δ\Delta transition form factors. We also discuss the scaling law and the subleading power corrections in the Breit and light-front frames.Comment: 24 pages,2 figure

    Genetic Determinants of Facial Clefting: Analysis of 357 Candidate Genes Using Two National Cleft Studies from Scandinavia

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    Facial clefts are common birth defects with a strong genetic component. To identify fetal genetic risk factors for clefting, 1536 SNPs in 357 candidate genes were genotyped in two population-based samples from Scandinavia (Norway: 562 case-parent and 592 control-parent triads; Denmark: 235 case-parent triads).We used two complementary statistical methods, TRIMM and HAPLIN, to look for associations across these two national samples. TRIMM tests for association in each gene by using multi-SNP genotypes from case-parent triads directly without the need to infer haplotypes. HAPLIN on the other hand estimates the full haplotype distribution over a set of SNPs and estimates relative risks associated with each haplotype. For isolated cleft lip with or without cleft palate (I-CL/P), TRIMM and HAPLIN both identified significant associations with IRF6 and ADH1C in both populations, but only HAPLIN found an association with FGF12. For isolated cleft palate (I-CP), TRIMM found associations with ALX3, MKX, and PDGFC in both populations, but only the association with PDGFC was identified by HAPLIN. In addition, HAPLIN identified an association with ETV5 that was not detected by TRIMM.Strong associations with seven genes were replicated in the Scandinavian samples and our approach effectively replicated the strongest previously known association in clefting--with IRF6. Based on two national cleft cohorts of similar ancestry, two robust statistical methods and a large panel of SNPs in the most promising cleft candidate genes to date, this study identified a previously unknown association with clefting for ADH1C and provides additional candidates and analytic approaches to advance the field
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