The Virgin HIV Puzzle: Can Misreporting Account for the High Proportion of HIV Cases in Self-Reported Virgins?

It is widely believed that HIV is predominantly sexually transmitted in Sub Saharan Africa. This claim which is inconsistent with national representative data from Lesotho, Zimbabwe, and Swaziland, which reveals that a significant proportion of HIV infections occurred in adolescents who claim to be virgins. Two explanations for this observation have been proposed: adolescents misreport sexual status or non-sexual risks are more prevalent than previously asserted. This paper empirically uncovers the implicit assumptions underlying this discussion, by estimating the proportion of sexually transmitted HIV infections assuming that misreporting is irrelevant, and the proportion of misreporting necessary to conclude that HIV is predominantly sexually transmitted. It shows that under the no-misreporting assumption, 70% of HIV cases in the respective sample of unmarried adolescent women is not due to sexual transmission. The assumption that HIV is predominantly sexually transmitted is only valid, if more than 55% of unmarried adolescent women who are sexually active have misreported sexual activity status. This research is designed to gain better understanding on the importance of different transmission modes. This is important to design combination prevention to achieve maximum impact on HIV prevention.Population attributable fraction; non-classical measurement error; HIV transmission mode

The Virgin HIV Puzzle: Can misreporting account for the high proportion of HIV cases in self-reported virgins?

The Demographic and Health Surveys from Lesotho, Zimbabwe, and Malawi reveal that a significant proportion of HIV infections in adolescent women occurred in women who claim to be virgin. Two possible conclusions arise from this observation: adolescent women misreport sexual status or non-sexual risk is more relevant than previously asserted. This paper uses a nonparametric model to estimate the proportion of HIV infections associated with sexual activity under different assumptions on data accuracy. It shows that there is an inverse relation between data accuracy and importance of sexual HIV transmission. If all adolescent women in the considered sub-sample correctly report sexual activity, 70% of HIV infections cannot be attributed to sexual HIV transmission. The model predicts that more than 95% of HIV infections are due to sexual HIV infections, if a substantial proportion of self-reported virgins (between 40 and 90%) misreport sexual status. --adolescent,HIV,misreporting,nonparametric modelling,sexual transmission

Evaluating Nationwide Health Interventions When Standard Before-After Doesn't Work: Malawi's ITN Distribution Program

Nationwide health interventions are difficult to evaluate as contemporaneous control groups do not exist and before-after approaches are usually infeasible. We propose an alternative semi-parametric estimator that is based on the assumption that the intervention has no direct effect on the health outcome but influences the outcome only through its effect on individual behavior. We show that in this case the evaluation problem can be divided into two parts: (i) the effect of the intervention on behavior, for which a conditional before-after assumption is more plausible; and (ii) the effect of the behavior on the health outcome, where we exploit that a contemporaneous control groups exists for behavior. The proposed estimator is used to evaluate one of Malawi's main malaria prevention campaigns, a nationwide insecticide-treated-net (ITN) distribution scheme, in terms of its effect on infant mortality. We exploit that the program affects child mortality only via bed net usage. We find that Malawi's ITN distribution campaign reduced child mortality by 1 percentage point, which corresponds to about 30% of the total reduction in infant mortality over the study period.health intervention, semi-parametric estimation, treatment effect

Gross-Pitaevskii Limit of a Homogeneous Bose Gas at Positive Temperature

We consider a dilute, homogeneous Bose gas at positive temperature. The system is investigated in the Gross-Pitaevskii (GP) limit, where the scattering length $a$ is so small that the interaction energy is of the same order of magnitude as the spectral gap of the Laplacian, and for temperatures that are comparable to the critical temperature of the ideal gas. We show that the difference between the specific free energy of the interacting system and the one of the ideal gas is to leading order given by $4 \pi a \left( 2 \varrho^2 - \varrho_0^2 \right)$. Here $\varrho$ denotes the density of the system and $\varrho_0$ is the expected condensate density of the ideal gas. Additionally, we show that the one-particle density matrix of any approximate minimizer of the Gibbs free energy functional is to leading order given by the one of the ideal gas. This in particular proves Bose-Einstein condensation with critical temperature given by the one of the ideal gas to leading order. One key ingredient of our proof is a novel use of the Gibbs variational principle that goes hand in hand with the c-number substitution

Evaluating Nationwide Health Interventions When Standard Before-After Doesn't Work: Malawi's ITN Distribution Program

Nationwide health interventions are difficult to evaluate as contemporaneous control groups do not exist and before-after approaches are usually infeasible. We propose an alternative semi-parametric estimator that is based on the assumption that the intervention has no direct effect on the health outcome but influences the outcome only through its effect on individual behavior. We show that in this case the evaluation problem can be divided into two parts: (i) the effect of the intervention on behavior, for which a conditional before-after assumption is more plausible; and (ii) the effect of the behavior on the health outcome, where we exploit that a contemporaneous control groups exists for behavior. The proposed estimator is used to evaluate one of Malawi's main malaria prevention campaigns, a nationwide insecticide-treated-net (ITN) distribution scheme, in terms of its effect on infant mortality. We exploit that the program affects child mortality only via bed net usage. We find that Malawi's ITN distribution campaign reduced child mortality by 1 percentage point, which corresponds to about 30% of the total reduction in infant mortality over the study period.Treatment effect; semi-parametric estimation; health intervention

Emergence of non-abelian magnetic monopoles in a quantum impurity problem

Recently it was shown that molecules rotating in superfluid helium can be described in terms of the angulon quasiparticles (Phys. Rev. Lett. 118, 095301 (2017)). Here we demonstrate that in the experimentally realized regime the angulon can be seen as a point charge on a 2-sphere interacting with a gauge field of a non-abelian magnetic monopole. Unlike in several other settings, the gauge fields of the angulon problem emerge in the real coordinate space, as opposed to the momentum space or some effective parameter space. Furthermore, we find a topological transition associated with making the monopole abelian, which takes place in the vicinity of the previously reported angulon instabilities. These results pave the way for studying topological phenomena in experiments on molecules trapped in superfluid helium nanodroplets, as well as on other realizations of orbital impurity problems.Comment: 6 pages, 2 figure

Note on a Family of Monotone Quantum Relative Entropies

Given a convex function $\varphi$ and two hermitian matrices $A$ and $B$, Lewin and Sabin study in [M. Lewin, J. Sabin, {\it A Family of Monotone Quantum Relative Entropies}, Lett. Math. Phys. \textbf{104} (2014), 691-705.] the relative entropy defined by $\mathcal{H}(A,B)=\text{Tr} [ \varphi(A) - \varphi(B) - \varphi'(B)(A-B) ]$. Amongst other things, they prove that the so-defined quantity is monotone if and only if $\varphi'$ is operator monotone. The monotonicity is then used to properly define $\mathcal{H}(A,B)$ for self-adjoint bounded operators acting on an infinite-dimensional Hilbert space by a limiting procedure. More precisely, for an increasing sequence of finite-dimensional projections $\lbrace P_n \rbrace_{n=1}^{\infty}$ with $P_n \to 1$ strongly, the limit $\lim_{n \to \infty} \mathcal{H}(P_n A P_n, P_n B P_n)$ is shown to exist and to be independent of the sequence of projections $\lbrace P_n \rbrace_{n=1}^{\infty}$. The question whether this sequence converges to its "obvious" limit, namely $\text{Tr} [ \varphi(A)- \varphi(B) - \varphi'(B)(A-B) ]$, has been left open. We answer this question in principle affirmatively and show that $\lim_{n \to \infty} \mathcal{H}(P_n A P_n, P_n B P_n) = \text{Tr}[ \varphi(A) - \varphi(B) - \frac{\text{d}}{\text{d} \alpha} \varphi( \alpha A + (1-\alpha)B )|_{\alpha = 0} ]$. If the operators $A$ and $B$ are regular enough, that is $(A-B)$, $\varphi(A)-\varphi(B)$ and $\varphi'(B)(A-B)$ are trace-class, the identity $\text{Tr}[ \varphi(A) - \varphi(B) - \frac{\text{d}}{\text{d} \alpha} \varphi( \alpha A + (1-\alpha)B )|_{\alpha = 0} ] = \text{Tr} [ \varphi(A)- \varphi(B) - \varphi'(B)(A-B) ]$ holds.Comment: 21 page

Evaluating Nationwide Health Interventions when Standard Before-After Doesn't Work: Malawi's ITN Distribution Program

Nationwide health interventions are difficult to evaluate as contemporaneous control groups do not exist and before-after approaches are usually infeasible. We propose an alternative semi-parametric estimator that is based on the assumption that the intervention has no direct effect on the health outcome but influences the outcome only through its effect on individual behavior. We show that in this case the evaluation problem can be divided into two parts: (i) the effect of the intervention on behavior, for which a conditional before-after assumption is more plausible; and (ii) the effect of the behaviour on the health outcome, where we exploit that a contemporaneous control groups exists for behavior. The proposed estimator is used to evaluate one of Malawi’s main malaria prevention campaigns, a nationwide insecticide-treated-net (ITN) distribution scheme, in terms of its effect on infant mortality. We exploit that the program affects child mortality only via bed net usage. We find that Malawi’s ITN distribution campaign reduced child mortality by 1 percentage point, which corresponds to about 30% of the total reduction in infant mortality over the study period.treatment effect, semi-parametric estimation, health intervention

The tempest: Using a natural disaster to evaluate the link between wealth and child development

How does family wealth affect children's development in the short- and long-run? We address this question by exploiting a shock occurred to family’s real estate, i.e. housing damages caused by a super typhoon. Our identification strategy is based on a comparison of children, who all lived in the same local area and thus were confronted with the same macro-economic shock, but only some experienced housing damages. We present evidence in favor of housing damages being essentially a severe wealth shock, with no effects on other observable channels which might directly harm children’s development. The shock results in a decline of educa-tional investments, but not of health-related investments. We observe a deterioration of chil-dren’s educational achievements in the short-run and even more pronounced in the long-run. Our findings are mainly driven by children whose families are at the bottom of the wealth distribution or lack the support of a strong family network.Child development, wealth effects, natural disaster

Persistence of translational symmetry in the BCS model with radial pair interaction

We consider the two-dimensional BCS functional with a radial pair interaction. We show that the translational symmetry is not broken in a certain temperature interval below the critical temperature. In the case of vanishing angular momentum our results carry over to the three-dimensional case.Comment: 17 pages, 1 figur