Property rights and efficiency in OLG models with endogenous fertility

Is there an economic rationale for pronatalist policies? We propose and analyze a particular market failure that leads to inefficiently low fertility in equilibrium. The friction is caused by the lack of ownership of children: if parents have no claim on their children’s income, the private benefit from producing a child can be smaller than the social benefit. We analyze an overlapping-generations model with fertility choice and parental altruism. Ownership is modeled as a minimum constraint on transfers from parents to children. Using the efficiency concepts proposed in Golosov, Jones, and Tertilt (2007), we find that whenever the transfer floor is binding, fertility choices are inefficient. Second, we show that the usual conditions for efficiency are not sufficient in this context. Third, in contrast to settings with exogenous fertility, a PAYG social security system cannot be used to implement efficient allocations. To achieve an efficient outcome, government transfers need to be tied to fertility choice. Keywords; overlapping generations, fertility, efficiency

Complements versus Substitutes and Trends in Fertility Choice in Dynastic Models

The Barro-Becker model is a simple intuitive model of fertility choice. In its original formulation, however, it has not been very successful at reproducing the changes in fertility choice in response to decreased mortality and increased income growth that demographers have emphasized in explaining the demographic transition. In this paper we show that this is due to an implicit assumption that number and utility of children are complements, which is a byproduct of the high intertemporal elasticity of substitution (IES) typically assumed in the fertility literature. We show that, not only is this assumption not necessary, but both the qualitative and quantitative properties of the model in terms of fertility choice change dramatically when substitutability and high curvature are assumed. To do so, we first derive analytical comparative statics and perform quantitative experiments. We find that if IES is less than one, model predictions of changes in fertility amount to about two-thirds of those observed in U.S. data since 1800. There are two major sources to these predicted changes, the increase in the growth rate of productivity which accounts for about 90 percent of the predicted fall in fertility before 1880, and changes in mortality which account for 90 percent of the predicted change from 1880 to 1950.

Parental child care during and outside of typical work hours

It has been argued that when analyzing time use data, child care should be treated separately from leisure or housework because, unlike these two, its income gradient is positive. Using U.S. data from PSID-CDS, this paper computes parental child care during and outside of typical work hours (TWH) by income quintile for two-parent families. The TWH distinction is important because during TWH the opportunity cost of spending time with children is first and foremost in terms of forgone earnings, while outside of TWH it is mainly in terms of leisure or housework. Indeed, I find that during TWH active child care is actually decreasing in income and, hence, behaves a lot like leisure and other household chores. Outside of TWH, fathers partly catch up to mothers especially in high income families. Indeed, mothers' child care is still slightly decreasing in income, while fathers' active care is increasing. Implications for theory are derived in a static framework of time allocation and child quality production which encompasses the recent literature on the topic. Similar to patterns in leisure and housework, the variation in child care during TWH can be rationalized by assuming a high elasticity of substitution between leisure, consumption and child quality where the substitution effect dominates the income effect. However, the facts outside of TWH point to systematic differences by income in preferences or productivity. For instance, assuming father's productivity in child care is increasing, while mother's is decreasing in income could be a potential rationale for the observed behavior

An Accounting Exercise for the Shift in Life-Cycle Employment Profiles of Married Women Born Between 1940 and 1960

Life-cycle employment profiles of married women born between 1940 and 1960 shifted upwards and became flatter. We calibrate a dynamic life-cycle model of employment decisions of married women to assess the quantitative importance of three competing explanations of the change in employment profiles: the decrease and delay in fertility, the increase in relative wages of women to men, and the decline in child-care costs. We find that the decrease and delay in fertility and the decline in child-care cost affect employment very early in life, while increases in relative wages affect employment increasingly with age. Changes in relative wages, in particular returns to experience, account for the bulk (67 percent) of changes in life-cycle employment of married women

Who Owns Children and Does it Matter?

Is there an economic rationale for pronatalist policies? In this paper we propose and analyze a particular market failure that may lead to inefficiently low equilibrium fertility and therefore to a need for government intervention. The friction we investigate is related to the ownership of children. If parents have no claim on their children’s income, then the private benefit from producing a child may be smaller than the social benefit. We present an overlapping-generations (OLG) model with fertility choice and altruism, and model ownership by introducing a minimum constraint on transfers from parents to children. Using the efficiency concepts proposed in Golosov, Jones, and Tertilt (2007), we find that whenever the transfer floor is binding, fertility choices are inefficient. We show how this inefficiency relates to dynamic inefficiency in standard OLG models with exogenous fertility and Millian efficiency in models with endogenous fertility. In particular, we show that the usual conditions for efficiency are no longer sufficient. Further, we analyze several government policies in this context. We find that, in contrast to settings with exogenous fertility, a PAYG social security system cannot be used to implement the efficient allocation. To achieve the efficient outcome, government transfers need to be tied to a person’s fertility choice in order to provide incentives for child-bearing.

Fertility Theories: Can They Explain the Negative Fertility-Income Relationship?

In this chapter we revisit the relationship between income and fertility. There is overwhelming empirical evidence that fertility is negatively related to income in most countries at most times. Several theories have been proposed in the literature to explain this somewhat puzzling fact. The most common one is based on the opportunity cost of time being higher for individuals with higher earnings. Alternatively, people might differ in their desire to procreate and accordingly some people invest more in children and less in market-specific human capital and thus have lower earnings. We revisit these and other possible explanations. We find that these theories are not as robust as is commonly believed. That is, several special assumptions are needed to generate the negative relationship. Not all assumptions are equally plausible. Such findings will be useful to distinguish alternative theories. We conclude that further research along these lines is needed.

Oligonucleotide-assisted cleavage and ligation: a novel directional DNA cloning technology to capture cDNAs. Application in the construction of a human immune antibody phage-display library

The use of oligonucleotide-assisted cleavage and ligation (ONCL), a novel approach to the capture of gene repertoires, in the construction of a phage-display immune antibody library is described. ONCL begins with rapid amplification of cDNA ends to amplify all members equally. A single, specific cut near 5′ and/or 3′ end of each gene fragment (in single stranded form) is facilitated by hybridization with an appropriate oligonucleotide adapter. Directional cloning of targeted DNA is accomplished by ligation of a partially duplex DNA molecule (containing suitable restriction sites) and amplification with primers in constant regions. To demonstrate utility and reliability of ONCL, a human antibody repertoire was cloned from IgG mRNA extracted from human B-lymphocytes engrafted in Trimera mice. These mice were transplanted with peripheral blood lymphocytes from Candida albicans infected individuals and subsequently immunized with C.albicans glyceraldehyde-3-phosphate dehydrogenase (GAPDH). DNA sequencing showed that ONCL resulted in efficient capture of gene repertoires. Indeed, full representation of all V(H) families/segments was observed showing that ONCL did not introduce cloning biases for or against any V(H) family. We validated the efficiency of ONCL by creating a functional Fab phage-display library with a size of 3.3 × 10(10) and by selecting five unique Fabs against GAPDH antigen

Engineering antibody heavy chain CDR3 to create a phage display Fab library rich in antibodies that bind charged carbohydrates.

peer reviewedA number of small charged carbohydrate moieties have been associated with inflammation and cancer. However, the development of therapeutic Abs targeting these moieties has been hampered by their low immunogenicity and their structural relationship to self-Ag. We report the design of an Ab repertoire enriched in Abs binding to small charged carbohydrates and the construction of a human Fab phagemid library, "FAB-CCHO." This library combines L chain Ig sequences from human donors and H chain synthetic diversity constructed in key Ag contact sites in CDRs 1, 2, and 3 of the human framework V(H)3-23. The H chain CDR3 has been engineered to enrich the library in Abs that bind charged carbohydrates by the introduction of basic residues at specific amino acid locations. These residues were selected on the basis of anti-carbohydrate Ab sequence alignment. The success of this design is demonstrated by the isolation of phage Abs against charged carbohydrate therapeutic target Ags such as sulfated sialyl-Lewis X glycan and heparan sulfate

Real-time PCR has advantages over culture-based methods in identifying major airway bacterial pathogens in chronic obstructive pulmonary disease: Results from three clinical studies in Europe and North America

IntroductionWe compared the performance of real-time PCR with culture-based methods for identifying bacteria in sputum samples from patients with chronic obstructive pulmonary disease (COPD) in three studies.MethodsThis was an exploratory analysis of sputum samples collected during an observational study of 127 patients (AERIS; NCT01360398), phase 2 study of 145 patients (NTHI-004; NCT02075541), and phase 2b study of 606 patients (NTHI-MCAT-002; NCT03281876). Bacteria were identified by culture-based microbiological methods in local laboratories using fresh samples or by real-time PCR in a central laboratory using frozen samples. Haemophilus influenzae positivity with culture was differentiated from H. haemolyticus positivity by microarray analysis or PCR. The feasibility of bacterial detection by culture-based methods on previously frozen samples was also examined in the NTHI-004 study.ResultsBacterial detection results from both culture-based and PCR assays were available from 2,293 samples from AERIS, 974 from the NTHI-004 study, and 1736 from the NTHI-MCAT-002 study. Quantitative real-time PCR (qPCR) showed higher positivity rates than culture for H. influenzae (percentages for each study: 43.4% versus 26.2%, 47.1% versus 23.6%, 32.7% versus 10.4%) and Moraxella catarrhalis (12.9% versus 6.3%, 19.0% versus 6.0%, 15.5% versus 4.1%). In the NTHI-004 and NTHI-MCAT-002 studies, positivity rates were higher with qPCR for Streptococcus pneumoniae (15.6% versus 6.1%, 15.5% versus 3.8%); in AERIS, a lower rate with qPCR than with culture (11.0% versus 17.4%) was explained by misidentification of S. pseudopneumoniae/mitis isolates via conventional microbiological methods. Concordance analysis showed lowest overall agreement for H. influenzae (82.0%, 75.6%, 77.6%), due mainly to culture-negative/qPCR-positive samples, indicating lower sensitivity of the culture-based methods. The lowest positive agreement (culture-positive/qPCR-positive samples) was observed for S. pneumoniae (35.1%, 71.2%, 71.2%). Bacterial load values for each species showed a proportion of culture-negative samples with a load detected by qPCR; for some samples, the loads were in line with those observed in culture-positive samples. In the NTHI-004 study, of fresh samples that tested culture-positive, less than 50% remained culture-positive when tested from freeze/thawed samples. In the NTHI-004 study, of fresh samples that tested culture-positive, less than 50% remained culture-positive when tested from freeze/thawed samples.DiscussionReal-time PCR on frozen sputum samples has enhanced sensitivity and specificity over culture-based methods, supporting its use for the identification of common respiratory bacterial species in patients with COPD