Interactions between Type III receptor tyrosine phosphatases and growth factor receptor tyrosine kinases regulate tracheal tube formation in Drosophila

The respiratory (tracheal) system of the Drosophila melanogaster larva is an intricate branched network of air-filled tubes. Its developmental logic is similar in some ways to that of the vertebrate vascular system. We previously described a unique embryonic tracheal tubulogenesis phenotype caused by loss of both of the Type III receptor tyrosine phosphatases (RPTPs), Ptp4E and Ptp10D. In Ptp4E Ptp10D double mutants, the linear tubes in unicellular and terminal tracheal branches are converted into bubble-like cysts that incorporate apical cell surface markers. This tube geometry phenotype is modulated by changes in the activity or expression of the epidermal growth factor receptor (Egfr) tyrosine kinase (TK). Ptp10D physically interacts with Egfr. Here we demonstrate that the Ptp4E Ptp10D phenotype is the consequence of the loss of negative regulation by the RPTPs of three growth factor receptor TKs: Egfr, Breathless and Pvr. Reducing the activity of any of the three kinases by tracheal expression of dominant-negative mutants suppresses cyst formation. By competing dominant-negative and constitutively active kinase mutants against each other, we show that the three RTKs have partially interchangeable activities, so that increasing the activity of one kinase can compensate for the effects of reducing the activity of another. This implies that SH2-domain downstream effectors that are required for the phenotype are likely to be able to interact with phosphotyrosine sites on all three receptor TKs. We also show that the phenotype involves increases in signaling through the MAP kinase and Rho GTPase pathways

The Boltzmann Equation in Classical and Quantum Field Theory

Improving upon the previous treatment by Mueller and Son, we derive the Boltzmann equation that results from a classical scalar field theory. This is obtained by starting from the corresponding quantum field theory and taking the classical limit with particular emphasis on the path integral and perturbation theory. A previously overlooked Van-Vleck determinant is shown to control the tadpole type of self-energy that can still appear in the classical perturbation theory. Further comments on the validity of the approximations and possible applications are also given.Comment: 22 pages, 3 eps figures. Version to appear in Physical Review

The Impact of Relative Cohort Size on U.S. Fertility, 1913-2001

This paper tests for the long-term and short-term relationships between fertility and relative cohort size for the United States using the annual time series data between 1913 and 2001. An error correction model, imbedded with the cointegration theory, is coupled with the general impulse response function. Empirical evidence on relationships is found lending support to the Easterlin hypothesis in that the change in relative cohort size is an important explanatory variable to include in studies of human fertility both in the short run and in the long-run for the United States. In addition, our results support the catching-up hypothesis and that the child tax deduction has been an important policy variable influencing births.catching-up, age structure, relative cohort size, Easterlin hypothesis, child tax deduction

Elliptic and triangular flow in event-by-event (3+1)D viscous hydrodynamics

We present results for the elliptic and triangular flow coefficients in Au+Au collisions at root-s=200 AGeV using event-by-event (3+1)D viscous hydrodynamic simulations. We study the effect of initial state fluctuations and finite viscosities on the flow coefficients v_2 and v_3 as functions of transverse momentum and pseudo-rapidity. Fluctuations are essential to reproduce the measured centrality dependence of elliptic flow. We argue that simultaneous measurements of v_2 and v_3 can determine eta/s more precisely.Comment: 4 pages, 5 figures, version 2 includes resonance decays in the results, references added, minor typos correcte

ASIAN DEMOGRAPHIC TRANSITION: AN INSTRUMENTAL-VARIABLES PANEL APPROACH

We examine patterns in fertility during the demographic transition using a panel data set across 25 Asian countries for 1975-2003. The adult female literacy rate is used as an instrumental variable for the endogenous female labor force participation rate, which has been unsolved in the population literature. The preliminary panel data analysis suggests that relative cohort size is significant in explaining the decline in fertility before controlling for simultaneity bias. This result, however, may be spurious. After considering the instrumental variables estimation in the panel data structure, the age structure variable no longer plays a dominant role in explaining declining fertility rates in many Asian countries. Systematic differences were found between East and South Asia. A policy implication in South Asia is that development may reduce fertility directly through increasing income rather than indirectly through a change in female labor force participation or urbanization. In East Asia, the indirect effects dominate.Fertility, Easterlin hypothesis, Transition Economies, Relative Cohort Size, Age Structure

Fertility in Sub-Saharan African Countries with Consideration to Health and Poverty

Fertility has begun to fall in Sub-Saharan Africa but it remains high on average and particularly for a few countries. This paper examines African fertility using a panel data set of 47 Sub-Saharan countries between 1962 and 2003. Fixed and random country effect estimates are made in models where the explanatory variables are suggested by the theory of the demographic transition as modified by Caldwell. Special attention is paid to the economic status of women, urbanization, the poverty level, and the health of the population including total health expenditures and the prevalence of HIV/AIDS. The results support Caldwell’s hypothesis and are generally supportive of hypothesis that a fertility transition is occurring. HIV/AIDS is found to have a negative impact on fertility.Africa, infant mortality, fertility, poverty, health

Signals of spinodal hadronization: strangeness trapping

If the deconfinement phase transformation of strongly interacting matter is of first-order and the expanding chromodynamic matter created in a high-energy nuclear collision enters the corresponding region of phase coexistence, a spinodal phase separation might occur. The matter would then condense into a number of separate blobs, each having a particular net strangeness that would remain approximately conserved during the further evolution. We investigate the effect that such `strangeness trapping' may have on strangeness-related hadronic observables. The kaon multiplicity fluctuations are significantly enhanced and thus provide a possible tool for probing the nature of the phase transition experimentally.Comment: 15 pages, 11 eps figure