How Beliefs About HIV Status affect Risky Behaviors: Evidence From Malawi, Second Version

This paper examines how beliefs about own HIV status affect sexual behavior. Risky behavior is measured as the propensity to engage in extramarital affairs or not use condoms. The empirical analysis is based on 2004 and 2006 data from the Malawi Diffusion and Ideational Change Project. Controlling for endogeneity between beliefs and risk-taking, we find that downward revisions in the belief of being HIV positive lead to a lower propensity to engage in extramarital affairs but have no effect on condom use. We show that the estimates provide a lower bound when there is measurement error in reported extra-marital affairs.Beliefs,AIDS,Malawi

How Beliefs about HIV Status Affect Risky Behaviors: Evidence from Malawi, Second Version

This paper examines whether and to what extent changes in beliefs about own HIV status induce changes in risky sexual behavior using data from married males living in three regions of Malawi. Risky behavior is measured as the propensity to engage in extramarital affairs. The empirical analysis is based on panel surveys for years 2006 and 2008 from the Malawi Diffusion and Ideational Change Project (MDICP), which contain detailed information on beliefs about HIV status and on sexual behaviors. Many individuals change their beliefs over time, because of opportunities to get tested for HIV and informational campaigns. We estimate the effect of belief revisions on the propensity to engage in extra-marital affairs using a panel data estimator developed by Arellano and Carrasco (2003), which accommodates unobserved heterogeneity as well as belief endogeneity arising from the dependence of current beliefs on lagged behaviors. We find that downward revisions in the belief of being HIV positive lead to an increased propensity to engage in extra-marital affairs and upward revisions to a decreased propensity. The estimates are shown to be robust to underreporting of affairs. Using our estimates and a standard epidemeological model of disease transmission, we find that increasing the responsiveness of beliefs to test results would reduce the HIV transmission rate as infected individuals reduce sexual behavior and decrease the likelihood that uninfected persons have contact with an HIV-positive person.AIDS, Malawi, Beliefs

How Beliefs about HIV Status Affect Risky Behaviors: Evidence from Malawi, Fifth Version

This paper examines how beliefs about own HIV status affect decisions to engage in risky sexual behavior using data on married males living in Malawi. Risky behavior is measured as the propensity to engage in extramarital affairs. The empirical analysis is based on panel surveys for years 2006 and 2008 from the Malawi Diffusion and Ideational Change Project (MDICP). Beliefs vary significantly over time in the data, in part because of HIV testing and informational campaigns. We estimate the effect of beliefs about own HIV status on risky behavior using a panel data estimator developed by Arellano and Carrasco (2003), which accommodates unobserved heterogeneity as well as belief endogeneity arising from the dependence of current beliefs on lagged behaviors. We find that beliefs are an important determinant of risky behavior, with downward revisions in the belief of being HIV positive increasing risky behavior and upward revisions decreasing it. We modify Arellano and Carrasco’s (2003) estimator to allow for underreporting of affairs and find the estimates to be relatively robust to underreporting. Using our estimates and a prototypical epidemiological model of disease transmission, we show that making individuals better informed about their HIV status, either by increasing the credibility of test results and/or increasing access to testing, would on net reduce the HIV transmission rate.Beliefs, Malawi, HIV

How Beliefs about HIV Status Affect Risky Behaviors: Evidence from Malawi, Sixth Version

This paper examines how beliefs about own HIV status affect decisions to engage in risky sexual behavior (as measured by extramarital affairs) and analyzes the potential for interventions that influence beliefs, such as HIV testing and informational campaigns, to reduce transmission rates. The empirical analysis is based on a panel survey of married males for years 2006 and 2008 from the Malawi Diffusion and Ideational Change Project (MDICP). In the data, beliefs about HIV status vary significantly geographically and over time, in part because of newly available testing opportunities and because of cultural differences. We estimate the effect of beliefs on risky behavior using Arellano and Carrasco’s (2003) semiparametric panel data estimator, which accommodates unobserved heterogeneity and belief endogeneity. Results show that changes in the belief of being HIV positive induce changes in risky behavior. Downward revisions in beliefs increase risky behavior and upward revisions decrease it. We modify Arellano and Carrasco’s (2003) estimator to allow for underreporting of extramarital affairs and find the estimates to be robust. Using the estimates and a prototypical epidemiological model of disease transmission, we show that better informing people about their HIV status on net reduces the population HIV transmission rate.Malawi,HIV,beliefs

Magnetization steps in Zn_(1-x)Mn_xO: Four largest exchange constants and single-ion anisotropy

Magnetization steps (MST's) from Mn pairs in several single crystals of Zn_(1-x)Mn_xO (0.0056<=x<=0.030, and in one powder (x=0.029), were observed. The largest two exchange constants, J1/kB=-18.2+/-0.5K and J1'/kB=-24.3+/-0.6K, were obtained from large peaks in the differential susceptibility, dM/dH, measured in pulsed magnetic fields, H, up to 500 kOe. These two largest J's are associated with the two inequivalent classes of nearest neighbors (NN's) in the wurtzite structure. The 29% difference between J1 and J1' is substantially larger than 13% in CdS:Mn, and 15% in CdSe:Mn. The pulsed-field data also indicate that, despite the direct contact between the samples and a superfluid-helium bath, substantial departures from thermal equilibrium occurred during the 7.4 ms pulse. The third- and fourth-largest J's were determined from the magnetization M at 20 mK, measured in dc magnetic fields H up to 90 kOe. Both field orientations H||c and H||[10-10] were studied. (The [10-10] direction is perpendicular to the c-axis, [0001].) By definition, neighbors which are not NN's are distant neighbors (DN's). The largest DN exchange constant (third-largest overall), has the value J/kB=-0.543+/-0.005K, and is associated with the DN at r=c. Because this is not the closest DN, this result implies that the J's do not decrease monotonically with the distance r. The second-largest DN exchange constant (fourth-largest overall), has the value J/kB=-0.080 K. It is associated with one of the two classes of neighbors that have a coordination number z=12, but the evidence is insufficient for a definite unique choice. The dependence of M on the direction of H gives D/kB=-0.039+/-0.008K, in fair agreement with -0.031 K from earlier EPR work.Comment: 12 pages, 10 figures. Submitted to PR

A Minimum-Labeling Approach for Reconstructing Protein Networks across Multiple Conditions

The sheer amounts of biological data that are generated in recent years have driven the development of network analysis tools to facilitate the interpretation and representation of these data. A fundamental challenge in this domain is the reconstruction of a protein-protein subnetwork that underlies a process of interest from a genome-wide screen of associated genes. Despite intense work in this area, current algorithmic approaches are largely limited to analyzing a single screen and are, thus, unable to account for information on condition-specific genes, or reveal the dynamics (over time or condition) of the process in question. Here we propose a novel formulation for network reconstruction from multiple-condition data and devise an efficient integer program solution for it. We apply our algorithm to analyze the response to influenza infection in humans over time as well as to analyze a pair of ER export related screens in humans. By comparing to an extant, single-condition tool we demonstrate the power of our new approach in integrating data from multiple conditions in a compact and coherent manner, capturing the dynamics of the underlying processes.Comment: Peer-reviewed and presented as part of the 13th Workshop on Algorithms in Bioinformatics (WABI2013

Algebraic analysis of quantum search with pure and mixed states

An algebraic analysis of Grover's quantum search algorithm is presented for the case in which the initial state is an arbitrary pure quantum state of n qubits. This approach reveals the geometrical structure of the quantum search process, which turns out to be confined to a four-dimensional subspace of the Hilbert space. This work unifies and generalizes earlier results on the time evolution of the amplitudes during the quantum search, the optimal number of iterations and the success probability. Furthermore, it enables a direct generalization to the case in which the initial state is a mixed state, providing an exact formula for the success probability.Comment: 13 page

Susceptibility Amplitude Ratios Near a Lifshitz Point

The susceptibility amplitude ratio in the neighborhood of a uniaxial Lifshitz point is calculated at one-loop level using field-theoretic and $\epsilon_{L}$-expansion methods. We use the Schwinger parametrization of the propagator in order to split the quadratic and quartic part of the momenta, as well as a new special symmetry point suitable for renormalization purposes. For a cubic lattice (d = 3), we find the result $\frac{C_{+}}{C_{-}} = 3.85$.Comment: 7 pages, late