Fertility and Social Security

The data show that an increase in government provided old-age pensions is strongly correlated with a reduction in fertility. What type of model is consistent with this finding? We explore this question using two models of fertility: one by Barro and Becker (1989), and one inspired by Caldwell (1978, 1982) and developed by Boldrin and Jones (2002). In Barro and Becker's model parents have children because they perceive their children's lives as a continuation of their own. In Boldrin and Jones' framework parents procreate because children care about their parents' utility, and thus provide them with old-age transfers. The effect of increases in government provided pensions on fertility in the Barro and Becker model is very small, whereas the effect on fertility in the Boldrin and Jones model is sizeable and accounts for between 55 and 65% of the observed Europe-U.S. fertility differences both across countries and across time.Social security ; Financial markets

On fast CP violating interactions in leptogenesis

We show that when the relevant CP violating interactions in leptogenesis are fast, the different matter density asymmetries are determined at each instant by a balance condition between the amount of asymmetry being created and destroyed. This fact allows to understand in a simple way many features of leptogenesis in the strong washout regime. In particular, we find some non-trivial effects of flavour changing interactions that conserve lepton number, which are specially relevant in models for leptogenesis that rely heavily on flavour effects.Comment: V2: To match published version in JCAP. Minor changes, including one figure, with respect to V1. 17 pages, 4 figure

Medicaid insurance in old age

The old age provisions of the Medicaid program were designed to insure retirees against medical expenses. We estimate a structural model of savings and medical spending and use it to compute the distribution of lifetime Medicaid transfers and Medicaid valuations across currently single retirees. Compensating variation calculations indicate that current retirees value Medicaid insurance at more than its actuarial cost, but that most would value an expansion of the current Medicaid program at less than its cost. These findings suggest that for current single retirees, the Medicaid program may be of the approximately right size

Savings After Retirement: A Survey

The saving patterns of retired U.S. households pose a challenge to the basic life-cycle model of saving. The observed patterns of out-of-pocket medical expenses, which rise quickly with age and income during retirement, and heterogeneous lifespan risk, can explain a significant portion U.S. savings during retirement. However, more work is needed to disentangle these precautionary saving motives from other motives, such as the desire to leave bequests. An important complementary question is why households do not buy more insurance against these risks. Going beyond total savings and looking at its components, including housing, and looking at other portfolio choices can help shed light on these questions

CP violation in scatterings, three body processes and the Boltzmann equations for leptogenesis

We obtain the Boltzmann equations for leptogenesis including decay and scattering processes with two and three body initial or final states. We present an explicit computation of the CP violating scattering asymmetries. We analyze their possible impact in leptogenesis, and we discuss the validity of their approximate expressions in terms of the decay asymmetry. In scenarios in which the initial heavy neutrino density vanishes, the inclusion of CP asymmetries in scatterings can enforce a cancellation between the lepton asymmetry generated at early times and the asymmetry produced at later times. We argue that a sizeable amount of washout is crucial for spoiling this cancellation, and we show that in the regimes in which the washouts are particularly weak, the inclusion of CP violation in scatterings yields a reduction in the final value of the lepton asymmetry. In the strong washout regimes the inclusion of CP violation in scatterings still leads to a significant enhancement of the lepton asymmetry at high temperatures; however, due to the independence from the early conditions that is characteristic of these regimes, the final value of the lepton asymmetry remains approximately unchanged.Comment: 24 pages, 6 figures. One appendix added. Some numerical results and corresponding figures (mainly fig. 3) corrected. Final version to be published in JHE

On the full Boltzmann equations for Leptogenesis

We consider the full Boltzmann equations for standard and soft leptogenesis, instead of the usual integrated Boltzmann equations which assume kinetic equilibrium for all species. Decays and inverse decays may be inefficient for thermalising the heavy-(s)neutrino distribution function, leading to significant deviations from kinetic equilibrium. We analyse the impact of using the full kinetic equations in the case of a previously generated lepton asymmetry, and find that the washout of this initial asymmetry due to the interactions of the right-handed neutrino is larger than when calculated via the integrated equations. We also solve the full Boltzmann equations for soft leptogenesis, where the lepton asymmetry induced by the soft SUSY-breaking terms in sneutrino decays is a purely thermal effect, since at T=0 the asymmetry in leptons cancels the one in sleptons. In this case, we obtain that in the weak washout regime (K ~< 1) the final lepton asymmetry can change up to a factor four with respect to previous estimates.Comment: 34 pages, 6 figures, to be published in JCA

Factors affecting the vaccination choices of pregnant women for their children. A systematic review of the literature

In recent years, an increase in vaccine hesitancy has led to a decrease in vaccination coverage in several countries. We conducted a systematic review of studies that assessed knowledge of and attitudes toward pediatric vaccinations, and the vaccination choices and their determinants among pregnant women. A total of 6,277 records were retrieved, and 16 full texts were included in the narrative synthesis. The published literature on the topic shows that, overall, pregnant women believe that vaccines are important for the protection of their children and the community, but various concerns and misunderstandings persist around vaccine safety and efficacy, which reduce the trust of expectant mothers in immunization. Nevertheless, such attitudes and choices vary depending on the vaccine being considered and the corresponding determinants should therefore be studied in the context of each specific vaccination. Further research on this topic is needed, particularly in non-western countries

Study of flavour dependencies in leptogenesis

We study the impact of flavours on the efficiency factors and give analytical and numerical results of the baryon asymmetry taking into account the different charged lepton Yukawa contributions and the complete (diagonal and off-diagonal) $L$ to $B-L$ conversion $A$ matrix. With this treatment we update the lower bound on the lightest right-handed neutrino mass.Comment: 13 pages, 11 figures. typos corrected, some formulae modified. 2 figures and discussion adde

Why Do Couples and Singles Save During Retirement?

While the savings of retired singles tend to fall with age, those of retired couples tend to rise. We estimate a rich model of retired singles and couples with bequest motives and uncertain longevity and medical expenses. Our estimates imply that while medical expenses are an important driver of the savings of middle-income singles, bequest motives matter for couples and highincome singles and generate transfers to nonspousal heirs whenever a household member dies. The interaction of medical expenses and bequest motives is a crucial determinant of savings for all retirees. Hence, to understand savings, it is important to model household structure, medical expenses, and bequest motives