Quantization of the scalar field in a static quantum metric

We investigate the Hamiltonian formulation of quantum scalar fields in a static quantum metric. We derive a functional integral formula for the propagator. We show that the quantum metric substantially changes the behaviour of the scalar propagator and the effective Yukawa potential.Comment: Latex, 12 page

Universal regular short distance behavior from an interaction with a scale invariant gravity

We assume that the fourdimensional quantum gravity is scale invariant at short distances. We show through a simple scaling argument that correlation functions of quantum fields interacting with gravity have a universal (more regular) short distance behavior.Comment: LaTeX, 4 page

Controlling periodic long-range signalling to drive a morphogenetic transition

Cells use signal relay to transmit information across tissue scales. However, the production of information carried by signal relay remains poorly characterised. To determine how the coding features of signal relay are generated, we used the classic system for long-range signalling: the periodic cAMP waves that drive Dictyostelium collective migration. Combining imaging and optogenetic perturbation of cell signalling states, we find that migration is triggered by an increase in wave frequency generated at the signalling centre. Wave frequency is regulated by cAMP wave circulation, which organises the long-range signal. To determine the mechanisms modulating wave circulation, we combined mathematical modelling, the general theory of excitable media and mechanical perturbations to test competing models. Models in which cell density and spatial patterning modulate the wave frequency cannot explain the temporal evolution of signalling waves. Instead, our evidence leads to a model where wave circulation increases the ability for cells to relay the signal, causing further increase in the circulation rate. This positive feedback between cell state and signalling pattern regulates the long-range signal coding that drives morphogenesis

Solutions of the Einstein-Dirac and Seiberg-Witten Monopole Equations

We present unique solutions of the Seiberg-Witten Monopole Equations in which the U(1) curvature is covariantly constant, the monopole Weyl spinor consists of a single constant component, and the 4-manifold is a product of two Riemann surfaces of genuses p_1 and p_2. There are p_1 -1 magnetic vortices on one surface and p_2 - 1 electric ones on the other, with p_1 + p_2 \geq 2 p_1 = p_2= 1 being excluded). When p_1 = p_2, the electromagnetic fields are self-dual and one also has a solution of the coupled euclidean Einstein-Maxwell-Dirac equations, with the monopole condensate serving as cosmological constant. The metric is decomposable and the electromagnetic fields are covariantly constant as in the Bertotti-Robinson solution. The Einstein metric can also be derived from a K\"{a}hler potential satisfying the Monge-Amp\`{e}re equations.Comment: 22 pages. Rep. no: FGI-99-

Influences on Youth Sexual Behaviour in Central Java: Implication of Sexual and Reproductive Health Policy and Services

Indonesian youth nowadays have been experiencing an increasing vulnerability to various kind of healthhazards specially related to reproductive and sexual health, including the growing threat of HIV/AIDS. This paperreports on findings from a study undertaken during the year 2003-2004 among urban youth in Central Java. The studyseeks to identify factors influencing youth sexual behavior and their need for services, in order to derive practical policyfor enhancing youth sexual and reproductive health services. The study involved a total of 2000 samples derived from ayouth population, aged 18-24 years old. A group of 1000 samples was randomly selected from a working youthpopulation through factory employers, whereas the other 1000 samples were from middle class youth among universitystudents. Social learning theory was applied as a base of the conceptual framework of the study with quantitativesurveys and qualitative methods The findings showed that the overall pattern of sexual and reproductive youth healthrisk were relatively low in comparison to that in many other countries, which was partly related to distinctive andpositive characteristics of the culture of the community in Central Java. The findings also showed that self efficacy wasthe strongest influencing factor on youth sexual behavior. Future policies and program development should be addressedto the ways in maintaining young peoples positive norms and values in line with the existing culture and religion byenhancing their self efficacy through school-based sexual and reproductive health education and services. Advocacyshould also be used continuously to address environmental constraints that impede the adoption of healthy reproductivehealth behavior

Determinants of Youth Sexual Behaviour and Its Implications to Reproductive and Sexual Health Policies and Services in Central Java

Background : Indonesian young people have been facing significant challenges to their health and well-being. This situation has causing an increased vulnerability to health hazards of various kinds, specially related to reproductive and sexual health, including the growing threat of HIV/AIDS. These adolescent health issues, most of which are preventable, can lead to significant morbidity and mortality.Method : This paper reports on findings from a recent study, which seeks to identify predictor factors of youth sexual behaviour and their need for services, in order to derive practical policy for enhancing youth sexual and reproductive health services. Involving a total 2000 sample derived from youth population aged 18-24 years old. 1000 samples were each randomly selected from factory employers and university students.Result : The findings show that the overall pattern of sexual and reproductive youth health risk is relatively low in comparison to that in many other countries, this is partly related to distinctive and positive characteristics of the culture of Central Java. The findings also showthat Self-efficacy is the strongest predictor of youth sexual behaviour.This study recommends that future policy and program should address how to protect oneself if engaging in sex, rather than only focusing on how to abstain from sex. Such policies and program development should be addressed to the ways to maintaining young people's positivenorms and values in line with existing culture and religion by enhancing their self efficacy and life-skill through school-based sexual and reproductive health education and services.Keywords : Health services, reproductive and sexual health, sexual behaviour, javaneseyouth

Does backreaction enforce the averaged null energy condition in semiclassical gravity?

The expected stress-energy tensor of quantum fields generically violates the local positive energy conditions of general relativity. However, may satisfy some nonlocal conditions such as the averaged null energy condition (ANEC), which would rule out traversable wormholes. Although ANEC holds in Minkowski spacetime, it can be violated in curved spacetimes if one is allowed to choose the spacetime and quantum state arbitrarily, without imposition of the semiclassical Einstein equation G_{ab} = 8 \pi . In this paper we investigate whether ANEC holds for solutions to this equation, by studying a free, massless scalar field with arbitrary curvature coupling in perturbation theory to second order about the flat spacetime/vacuum solution. We "reduce the order" of the perturbation equations to eliminate spurious solutions, and consider the limit in which the lengthscales determined by the incoming state are much larger than the Planck length. We also need to assume that incoming classical gravitational radiation does not dominate the first order metric perturbation. We find that although the ANEC integral can be negative, if we average the ANEC integral transverse to the geodesic with a suitable Planck scale smearing function, then a strictly positive result is obtained in all cases except for the flat spacetime/vacuum solution. This result suggests --- in agreement with conclusions drawn by Ford and Roman from entirely independent arguments --- that if traversable wormholes do exist as solutions to the semiclassical equations, they cannot be macroscopic but must be ``Planck scale''. A large portion of our paper is devoted to the analysis of general issues concerning the nature of the semiclassical Einstein equation and of prescriptions for extracting physically relevant solutions.Comment: 54 pages, 3 figures, uses revtex macros and epsf.tex, to appear in Phys Rev D. A new appendix has been added showing consistency of our results with recent results of Visser [gr-qc/9604008]. Some corrections were made to Appendix A, and several other minor changes to the body of the paper also were mad

Social Learning Theory in Youth Sexual Behaviour Study in Central Java

Background: Many public health researchers in Indonesia have advocated a greater role for the use of theory in strengthening the practice of research. However, public health researches and sexual & reproductive health researches in Indonesia have continued to focus primarilyon evaluating outcomes with less attention to the mechanisms by which these outcomes are produced. In this situation they argue that research is reduced to a set of predetermined steps that are mechanically applied to various interventions without concern for the theoretical implications of intervention content, setting, participants or implementing organizations. Such simple evaluations may provide a gross assessment of whether or not an intervention works under one set of conditions but fail to identify the reasons why (Brazil K., Ozer E., et all, 2005). As such, the conclusions are often less than satisfying to consumers of research resultsand not easily transferable to different settings.Method: The study applied a cross-sectional design, involving a total 2000 sample derived from youth population aged 18-24 years old, 1000 samples were each randomly selected from factory employers and university students in urban Central Java. The study employed quan-titative (survey) method using structured questionnaire as instrument and qualitative method (in-depth interviews and FGDs).Result : Although the findings of this cross-sectional study do not demonstrate that change in those factors/variables will reduce risk sexual behavior, they do suggest that future development and evaluation of sexual and reproductive health programs in youth population shouldtest the feasibility and the effect of changing those personal/cognitive and environment factors. Demonstrating causality would have required the experimental manipulation of self efficacy beliefs and a test of their effects on sexual behavior in a prospective rather than cross-sectional design. It is important to provide an open environment and counseling re-sources to the youth population in Central Java for strengthening youth self-efficacy which will increasing youth's ability to avoid and/or reduce risky sexual behaviour. There is clearly a need for the reviewing of various laws, regulations, and policies at the central and regional level in order to develop more conducive environment for improving knowledge, attitude and practice of adolescent's sexual lifestyl