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Using biodegradable instead of conventional plastics in agricultural applications promises to help overcome plastic pollution of agricultural soils. However, analytical limitations impede our understanding of plastic biodegradation in soils. Utilizing stable carbon isotope (13C-)labelled poly(butylene succinate) (PBS), a synthetic polyester, we herein present an analytical approach to continuously quantify PBS mineralization to 13CO2 during soil incubations and, thereafter, to determine non-mineralized PBS-derived 13C remaining in the soil. We demonstrate extensive PBS mineralization (65 % of added 13C) and a closed mass balance on PBS−13C over 425 days of incubation. Extraction of residual PBS from soils combined with kinetic modeling of the biodegradation data and results from monomer (i.e., butanediol and succinate) mineralization experiments suggest that PBS hydrolytic breakdown controlled the overall PBS biodegradation rate. Beyond PBS biodegradation in soil, the presented methodology is broadly applicable to investigate biodegradation of other biodegradable polymers in various receiving environments. This study applies stable carbon isotope labelling to study polymer biodegradation in soils. This labelling enables accurate and precise tracking of polymer carbon during biodegradation and, thereby, provides a holistic picture of this process. [ABSTRACT FROM AUTHOR]

Young heterosexual men have low uptake of HIV prevention and treatment services and represent an important key population that may require novel strategies. We recruited 1271 heterosexual men, 12 years and older from socializing venues such as "shebeens", transport hubs, "spaza" shops, and community centers in rural KwaZulu-Natal, South Africa. Participants completed a questionnaire and were tested for HIV serostatus. Generalized estimating equations (GEE) with exchangeable covariance structure estimated factors independently associated with prevalent HIV infection. Median age was 25 years [Interquartile range (IQR) 21–29]. HIV prevalence was 15.5% [95% confidence interval (CI) 11.0–21.9] and increased significantly by age. Factors associated with higher odds of HIV infection were being 25 years and older [adjusted odds ratio (aOR) 4.82, 95% CI 3.47–6.69; p < 0.001), not completing high school (aOR 1.60, 95% CI 1.39–1.85; p < 0.001), not using condoms at first sex (aOR 1.43, 95% CI 1.20–1.70; p < 0.001), consuming alcohol (aOR 1.63, 95% CI 1.15–2.31; p = 0.006) or substances (aOR 1.37, 95% CI 1.31–1.44; p < 0.001), and absence of medical circumcision (aOR 2.05, 95% CI 1.71–2.44; p < 0.001). Risk was lower among those testing for HIV in last 12 months (aOR 0.54, 95% CI 0.36–0.80; p = 0.002). Greater effort is needed to implement innovative programs within settings that are easily accessible and where heterosexual men are likely to be. [ABSTRACT FROM AUTHOR]

Cognitive health is an important dimension of well-being in older ages, but few studies have investigated the demography of cognitive health in sub-Saharan Africa’s growing population of mature adults (= persons aged 45+). We use data from the Malawi Longitudinal Study of Families and Health to document the age and gender patterns of cognitive health, the contextual and life-course correlates of poor cognitive health, and the understudied linkages between cognitive and physical/mental well-being. Surprisingly, the age pattern of decline in cognitive health is broadly similar to that observed in the USA. We also find that women have substantially worse cognitive health than men and experience a steeper age gradient in cognitive ability. Strong social ties and exposure to socially complex environments are associated with higher cognitive health, as is higher socioeconomic status. Poor cognitive health is associated with adverse social and economic well-being outcomes such as less nutrition intake, lower income, and reduced work efforts even in this subsistence agriculture context. Lower levels of cognitive health are also strongly associated with increased levels of depression and anxiety and are associated with worse physical health measured through both self-reports and physical performance. Our findings suggest that cognition plays a key—but understudied—role in shaping late-life well-being in low-income populations. [ABSTRACT FROM AUTHOR]

Aminobacter sp. MSH1 uses the groundwater micropollutant 2,6-dichlorobenzamide (BAM) as sole source of carbon and energy. In the first step, MSH1 converts BAM to 2,6-dichlorobenzoic acid (2,6-DCBA) by means of the BbdA amidase encoded on the IncP-1β plasmid pBAM1. Information about the genes and degradation steps involved in 2,6-DCBA metabolism in MSH1 or any other organism is currently lacking. Here, we show that the genes for 2,6-DCBA degradation in strain MSH1 reside on a second catabolic plasmid in MSH1, designated as pBAM2. The complete sequence of pBAM2 was determined revealing that it is a 53.9 kb repABC family plasmid. The 2,6-DCBA catabolic genes on pBAM2 are organized in two main clusters bordered by IS elements and integrase genes and encode putative functions like Rieske mono-/dioxygenase, meta-cleavage dioxygenase, and reductive dehalogenases. The putative mono-oxygenase encoded by the bbdD gene was shown to convert 2,6-DCBA to 3-hydroxy-2,6-dichlorobenzoate (3-OH-2,6-DCBA). 3-OH-DCBA was degraded by wild-type MSH1 and not by a pBAM2-free MSH1 variant indicating that it is a likely intermediate in the pBAM2-encoded DCBA catabolic pathway. Based on the activity of BbdD and the putative functions of the other catabolic genes on pBAM2, a metabolic pathway for BAM/2,6-DCBA in strain MSH1 was suggested. [ABSTRACT FROM AUTHOR]

Despite its importance in studies of migrant health, selectivity of migrants-also known as migration health selection-has seldom been examined in sub-Saharan Africa (SSA). This neglect is problematic because several features of the context in which migration occurs in SSA-very high levels of HIV, in particular-differ from contextual features in regions that have been studied more thoroughly. To address this important gap, we use longitudinal panel data from Malawi to examine whether migrants differ from nonmigrants in pre-migration health, assessed via SF-12 measures of mental and physical health. In addition to overall health selection, we focus on three more-specific factors that may affect the relationship between migration and health: (1) whether migration health selection differs by destination (rural-rural, rural-town, and rural-urban), (2) whether HIV infection moderates the relationship between migration and health, and (3) whether circular migrants differ in pre-migration health status. We find evidence of the healthy migrant phenomenon in Malawi, where physically healthier individuals are more likely to move. This relationship varies by migration destination, with healthier rural migrants moving to urban and other rural areas. We also find interactions between HIV-infected status and health: HIV-infected women moving to cities are physically healthier than their nonmigrant counterparts. [ABSTRACT FROM AUTHOR]

Very few studies have investigated mental health in sub-Saharan Africa (SSA). Using data from Malawi, this article provides a first picture of the demography of depression and anxiety (DA) among mature adults (aged 45 or older) in a low-income country with high HIV prevalence. DA are more frequent among women than men, and individuals affected by one are often affected by the other. DA are associated with adverse outcomes, such as poorer nutrition intake and reduced work efforts. DA also increase substantially with age, and mature adults can expect to spend a substantial fraction of their remaining lifetime-for instance, 52 % for a 55-year-old woman-affected by DA. The positive age gradients of DA are not due to cohort effects, and they are in sharp contrast to the age pattern of mental health that has been shown in high-income contexts, where older individuals often experience lower levels of DA. Although socioeconomic and risk- or uncertainty-related stressors are strongly associated with DA, they do not explain the positive age gradients and gender gap in DA. Stressors related to physical health, however, do. Hence, our analyses suggest that the general decline of physical health with age is the key driver of the rise of DA with age in this low-income SSA context. [ABSTRACT FROM AUTHOR]

LinA-type1 and LinA-type2 are two well-characterized variants of the enzyme 'hexachlorocyclohexane (HCH)-dehydrochlorinase'. They differ from each other at ten amino acid positions and exhibit differing enantioselectivity for the transformation of the (-) and (+) enantiomers of α-HCH. Amino acids responsible for this enantioselectivity, however, are not known. An in silico docking analysis identified four amino acids (K20, L96, A131, and T133) in LinA-type1 that could be involved in selective binding of the substrates. Experimental studies with constructed mutant enzymes revealed that a combined presence of three amino acid changes in LinA-type1, i.e. K20Q, L96C, and A131G, caused a reversal in its preference from the (-) to the (+) enantiomer of α-HCH. This preference was enhanced by the additional amino acid change T133 M. Presence of these four changes also caused the reversal of enantioselectivity of LinA-type1 for δ-HCH, and β-, γ-, and δ-pentachlorocyclohexens. Thus, the residues K20, L96, A131, and T133 in LinA-type1 and the residues Q20, C96, G131, and M133 in LinA-type 2 appear to be important determinants for the enantioselectivity of LinA enzymes. [ABSTRACT FROM AUTHOR]

Contrary to conventional wisdom, recent studies argue that parenthood is not necessarily related to higher parental subjective well-being (SWB). However, parenthood remains an important aspect of adults' lives, also in highly developed societies where childbearing has become optional, financially expensive and affecting other goals in life. Whereas a great deal of effort has been put into answering why fertility is low in so many developed countries, one may even ask why is it not even lower. The answer is not obvious but stems from the fact that, to date, the relationship between fertility and SWB has been understudied and the mechanisms at work are not well understood. This special issue makes a step forward in this line of research, providing a coherent set of papers addressing different dimensions of the relationship between fertility and SWB and its mechanisms, starting from a demographic perspective, but integrating theories and research results from other disciplines. The collection of papers assesses the effect of the birth of a child on the individual SWB from angles still unexplored with the idea that the effects of fertility on individuals' SWB are diverse depending on individual, couple and country contextual factors. [ABSTRACT FROM AUTHOR]

Hexachlorocyclohexane (HCH) contaminated soils were treated for a period of up to 64 days in situ (HCH dumpsite, Lucknow) and ex situ (University of Delhi) in line with three bioremediation approaches. The first approach, biostimulation, involved addition of ammonium phosphate and molasses, while the second approach, bioaugmentation, involved addition of a microbial consortium consisting of a group of HCH-degrading sphingomonads that were isolated from HCH contaminated sites. The third approach involved a combination of biostimulation and bioaugmentation. The efficiency of the consortium was investigated in laboratory scale experiments, in a pot scale study, and in a full-scale field trial. It turned out that the approach of combining biostimulation and bioaugmentation was most effective in achieving reduction in the levels of α- and β-HCH and that the application of a bacterial consortium as compared to the action of a single HCH-degrading bacterial strain was more successful. Although further degradation of β- and δ-tetrachlorocyclohexane-1,4-diol, the terminal metabolites of β- and δ-HCH, respectively, did not occur by the strains comprising the consortium, these metabolites turned out to be less toxic than the parental HCH isomers. [ABSTRACT FROM AUTHOR]

This article assesses how married individuals' knowledge of HIV status gained through HIV testing and counseling (HTC) affects divorce, the number of sexual partners, and the use of condoms within marriage. This study improves upon previous studies on this topic because the randomized incentives affecting the propensity to be tested for HIV permit control for selective testing. Instrumental variable probit and linear models are estimated, using a randomized experiment administered as part of the Malawi Longitudinal Study of Families and Health (MLSFH). The results indicate that knowledge of HIV status (1) does not affect chances of divorce for either HIV-negative or HIV-positive respondents; (2) reduces the number of reported sexual partners among HIV-positive respondents; and (3) increases reported condom use with spouses for both HIV-negative and HIV-positive respondents. These results imply that individuals actively respond to information about their HIV status that they learn during HTC, invoking protective behavior against future risk of HIV/AIDS for themselves and their actual and potential sexual partners. Some limitations of this study are a small sample size for those who are HIV-positive and dependence on self-reported sexual behaviors. [ABSTRACT FROM AUTHOR]

The empirical literature on the impact of HIV on the quality (Q) and quantity (N) of children provides limited and somewhat mixed evidence. This study introduces individual HIV risk perceptions, as a predictor of mortality, into a Q-N investment model. In this model, higher maternal mortality predicts lower N, while higher child mortality predicts lower Q. Thus, the two effects together make likely negative associations between HIV and both Q and N. Based on longitudinal micro-data on mothers and their children in rural Malawi, our results suggest that higher mothers' reported HIV risk reduces both child quality, as reflected in children's schooling and health, and child quantity, when the perceived risk is already moderate or high. The effects are sizable and, in the case of Q (schooling and health), are found for children and teenagers, both boys and girls, while in the case of N, they are found for young and mature women. [ABSTRACT FROM AUTHOR]

Empirical estimates of the association between concurrent partnerships (CP) and HIV risk are affected by non-sampling errors in survey data on CPs, e.g., because respondents misreport the extent of their CPs. We propose a new approach to measuring CPs in couples, which permits assessing how respondent errors affect estimates of the association between CPs and HIV risk. Each couple member is asked (1) to report whether s/he has engaged in CPs and (2) to assess whether his/her partner has engaged in CPs, since their couple started. Cross-tabulating these data yields multiple classifications (with varying combinations of sensitivity/specificity) of the CPs of each couple member. We then measure the association between CPs and HIV outcomes according to each classification. The resulting range of estimates is an indicator of the uncertainty associated with respondent errors. We tested this approach using data on 520 matched couples drawn from the Likoma Network Study. Results suggest that existing tests of the concurrency hypothesis are affected by significant uncertainty. [ABSTRACT FROM AUTHOR]

The widespread agricultural application of carbofuran and concomitant contamination of surface and ground waters has raised health concerns due to the reported toxic effects of this insecticide and its degradation products. Most bacteria that degrade carbofuran only perform partial degradation involving carbamate hydrolysis without breakdown of the resulting phenolic metabolite. The capacity to mineralize carbofuran beyond the benzofuran ring has been reported for some bacterial strains, especially sphingomonads, and some common metabolites, including carbofuran phenol, were identified. In the current study, the catabolism of carbofuran by Novosphingobium sp. KN65.2 (LMG 28221), a strain isolated from a carbofuran-exposed Vietnamese soil and utilizing the compound as a sole carbon and nitrogen source, was studied. Several KN65.2 plasposon mutants with diminished or abolished capacity to degrade and mineralize carbofuran were generated and characterized. Metabolic profiling of representative mutants revealed new metabolic intermediates, in addition to the initial hydrolysis product carbofuran phenol. The promiscuous carbofuran-hydrolyzing enzyme Mcd, which is present in several bacteria lacking carbofuran ring mineralization capacity, is not encoded by the Novosphingobium sp. KN65.2 genome. An alternative hydrolase gene required for this step was not identified, but the constitutively expressed genes of the unique cfd operon, including the oxygenase genes cfdC and cfdE, could be linked to further degradation of the phenolic metabolite. A third involved oxygenase gene, cfdI, and the transporter gene cftA, encoding a TonB-dependent outer membrane receptor with potential regulatory function, are located outside the cfd cluster. This study has revealed the first dedicated carbofuran catabolic genes and provides insight in the early steps of benzofuran ring degradation. [ABSTRACT FROM AUTHOR]

We investigate the causal impact of learning HIV status on HIV/AIDS-related expectations and sexual behavior in the medium run. Our analyses document several unexpected results about the effect of learning one's own, or one's spouse's, HIV status. For example, receiving an HIV-negative test result implies higher subjective expectations about being HIV-positive after two years, and individuals tend to have larger prediction errors about their HIV status after learning their HIV status. If individuals in HIV-negative couples also learn the status of their spouse, these effects disappear. In terms of behavioral outcomes, our analyses document that HIV-positive individuals who learned their status reported having fewer partners and using condoms more often than those who did not learn their status. Among married respondents in HIV-negative couples, learning only one's own status increases risky behavior, while learning both statuses decreases risky behavior. In addition, individuals in sero-discordant couples who learned both statuses are more likely to report some condom use. Overall, our analyses suggest that ensuring that each spouse learns the HIV status of the other, either through couple's testing or through spousal communication, may be beneficial in high-prevalence environments. [ABSTRACT FROM AUTHOR]

In silico analysis of nucleotide sequences flanking the recently found hydroquinone dioxygenase in Sphingomonas sp. strain TTNP3 revealed a gene cluster that encodes a hydroquinone catabolic pathway. In addition to the two open-reading frames encoding the recently characterized hydroquinone dioxygenase, the cluster consisted of six open-reading frames. We were able to express the three open-reading frames, hqdC, hqdD, and hqdE, and demonstrated that the three gene products, HqdC, HqdD, and HqdE had 4-hydroxymuconic semialdehyde dehydrogenase, maleylacetate reductase, and intradiol dioxygenase activity, respectively. Surprisingly, the gene cluster showed similarities to functionally related clusters found in members of the β- and γ-proteobacteria rather than to those found in other members of the genus Sphingomonas sensu latu. [ABSTRACT FROM AUTHOR]

Hydroquinone-1,2-dioxygenase, an enzyme involved in the degradation of alkylphenols in Sphingomonas sp. strain TTNP3 was purified to apparent homogeneity. The extradiol dioxygenase catalyzed the ring fission of hydroquinone to 4-hydroxymuconic semialdehyde and the degradation of chlorinated and several alkylated hydroquinones. The activity of 1 mg of the purified enzyme with unsubstituted hydroquinone was 6.1 μmol per minute, the apparent K 2.2 μM. ICP-MS analysis revealed an iron content of 1.4 moles per mole enzyme. The enzyme lost activity upon exposure to oxygen, but could be reactivated by Fe(II) in presence of ascorbate. SDS-PAGE analysis of the purified enzyme yielded two bands of an apparent size of 38 kDa and 19 kDa, respectively. Data from MALDI-TOF analyses of peptides of the respective bands matched with the deduced amino acid sequences of two neighboring open reading frames found in genomic DNA of Sphingomonas sp strain TTNP3. The deduced amino acid sequences showed 62% and 47% identity to the large and small subunit of hydroquinone dioxygenase from Pseudomonas fluorescens strain ACB, respectively. This heterotetrameric enzyme is the first of its kind found in a strain of the genus Sphingomonas sensu latu. [ABSTRACT FROM AUTHOR]

Schooling generally is positively associated with better health-related outcomes-for example, less hospitalization and later mortality-but these associations do not measure whether schooling causes better health-related outcomes. Schooling may in part be a proxy for unobserved endowments-including family background and genetics-that both are correlated with schooling and have direct causal effects on these outcomes. This study addresses the schooling-health-gradient issue with twins methodology, using rich data from the Danish Twin Registry linked to population-based registries to minimize random and systematic measurement error biases. We find strong, significantly negative associations between schooling and hospitalization and mortality, but generally no causal effects of schooling. [ABSTRACT FROM AUTHOR]

Background, aim and scope Ria de Aveiro (Portugal) is a shallow coastal lagoon of high economic and ecological importance. Hardly any data on its chemical pollution by polar organic pollutants are available in literature. This study focused on the presence and sources of a series of phenolic endocrine-disrupting compounds (EDCs) in this area, including parabens, alkylphenolic compounds and bisphenol-A (BPA). A number of possible sources of pollution are present in the area, including the large harbours present in the lagoon, the city of Aveiro and the rivers discharging into the area. A recently constructed submarine wastewater outfall, located a few kilometres from the lagoon inlet has also been suggested as a possible source of pollution to Ria de Aveiro in several publications. The aim of the current field study was to investigate the occurrence and main sources of phenolic endocrine disruptors in Ria de Aveiro. Materials and methods An extensive sampling campaign was performed, with surface water and wastewater grab samples taken at over 50 locations, in duplicate on different days. Samples were treated using solid phase extraction and analysed by liquid chromatography tandem mass spectrometry. Results and discussion Concentrations in lagoon water were generally low: not exceeding 20 ng/L for most analytes. Levels in river water exceeded those in the lagoon by a factor 3 to 500 (o-phenylphenol (PhP) and nonylphenoxy ethoxy acetic acids (A9PEC), respectively), with concentrations up to 700 ng/L for BPA and 7,300 ng/L for A9PEC. Samples from the harbours showed EDC levels similar to those in the rest of the lagoon, but in the city of Aveiro, elevated concentrations were observed for alkylphenol ethoxylates (A9PEO), A9PEC, PhP and BPA. Wastewater effluents showed low levels for parabens, whilst alkylphenolic compounds reached several micrograms per litre. The effluents are discharged into the ocean via a submarine outfall, but as marine water near the outfall showed slightly elevated concentrations only for A9PEO, it does not seem to be a significant source of these EDCs for the area. Conclusions All the studied phenolic EDCs were detected in the study area, with high levels found in some of the rivers discharging into the lagoon, and generally low concentrations in the lagoon itself. The main sources for all investigated EDCs were the rivers Caster and Antuã which discharge into the lagoon. The city of Aveiro was identified as a secondary source. As the tidal water exchange volume is much larger than the freshwater input from the rivers, concentrations of phenolic EDCs remained low in the lagoon. [ABSTRACT FROM AUTHOR]

Understanding the determinants of individuals' perceptions of their risk of becoming infected with HIV and their perceptions of acceptable strategies of prevention is an essential step toward curtailing the spread of this disease. We focus in this article on learning and decision-making about AIDS in the context of high uncertainty about the disease and appropriate behavioral responses. We argue that social interactions are important for both. Using longitudinal survey data from rural Kenya and Malawi, we test this hypothesis. We investigate whether social interactions--and especially the extent to which social network partners perceive themselves to be at risk--exert causal influences on respondents' risk perceptions and on one approach to prevention, spousal communication about the threat of AIDS to the couple and their children. The study explicitly allows for the possibility that important characteristics, such as unobserved preferences or community characteristics, determine not only the outcomes of interest but also the size and composition of networks. The most important empirical result is that social networks have significant and substantial effects on risk perceptions and the adoption of new behaviors even after we control for unobserved factors. [ABSTRACT FROM AUTHOR]

DeFries-Fulker (DF) Analysis for unselected populations is reformulated as a no-intercept model with centered variables and only two independent variables. The reformulation serves three purposes. First, the original formulation implicitly estimated two different values forc2 and two values forh2 . The new formulation resolves this ambiguity. Second, because the original formulation estimatedh2 with the coefficient from a regression-interaction term, whether to center the interaction variables was unclear. The new formulation explicitly resolves this issue. Finally, the new formulation estimates fewer parameters, and therefore improves estimation efficiency and statistical power. [ABSTRACT FROM AUTHOR]

Despite increasing research on the causes, consequences, and measurement of low fertility, questions about the nature and the extent of popular concerns over low fertility have yielded more speculation than examination. We address this gap in the literature through an analysis of 328 German newspaper and news magazine articles mentioning low fertility from 1993 to 2001. Our analysis reveals a paradox: while fertility rates have remained well below replacement levels and governmental discussions of low fertility have increased, discussion of low fertility as a concern in and of itself has been small and unchanging over time. We find this to be true because the problem of low fertility is rarely invoked as a concern in its own right, but is most often used as a tool in the popular debate to discuss other problems - political, economic, and cultural. [ABSTRACT FROM AUTHOR]

We investigated the timing of fertility and marriage in Sweden using exogenous variation in the age at school graduation that results from differences in birth month. Our analysis found that the difference of 11 months in the age at leaving school between women who were born in two consecutive months, December and January, implies a delay in the age at first birth of 4.9 months. This effect of delayed graduation also persists for the timing of second births and first marriages, but it does not affect completed fertility or the overall probability of marriage before age 45. These results suggest the existence of a relatively rigid sequencing of demographic events in early adulthood, and the age at graduation from school emerges as an important factor in determining the timing--but not the quantum--of familyformation. In addition, these effects point to a potentially important influence of social age, defined by an individual's school cohort, instead of biological age. The relevance of social age is likely due to social interactions and peer-group influences exerted by individuals who are in the same school cohort but are not necessarily of the same age. [ABSTRACT FROM AUTHOR]

Aspects of below-replacement fertility have long been debated among professional demographers. This paper describes the corresponding popular debate about low fertility by analyzing 437 newspaper and magazine articles from eleven developed countries during 1998 and 1999. Despite the diversity in the national debates due to different socioeconomic, political and demographic backgrounds, our study finds important commonalties in the way low fertility is debated: First, countries emphasize consequences and potential interventions rather than causes in their popular debates over low fertility. Second, our study reveals that the popular press discusses low fertility as a serious concern with mostly negative implications, despite the fact that many of the causes of low fertility are associated with social and economic progress. Third, the variety of issues and perspectives revealed in the popular debate, while cohesive in general ways, invites a role for demographers in informing an accurate public discussion of low fertility, which will help form the most appropriate policy outcomes. [ABSTRACT FROM AUTHOR]

The impacts of social networks on changes in contraception in rural Kenya are investigated using special data from a longitudinal household survey. An analytic model, informed by detailed knowledge of the setting, yielded estimates that indicate that (1) social networks have substantial effects even after unobserved factors (e.g., homophily) that may determine social networks are controlled; (2) controlling for these unobserved factors may substantially alter the estimated effects of networks (these controls were not used in previous studies); (3) network effects are important for both men and women; and (4) network effects are nonlinear and asymmetric, suggesting that networks provide information primarily through social learning, rather than by exerting social influence. [ABSTRACT FROM AUTHOR]

This paper analyses the fertility decline in Russia during theearly and mid 1990s from both a macro- and micro-perspective and presents astriking divergence between these two empirical viewpoints. While the formersuggests that the fertility decline after 1989 is associated with theeconomic hardship accompanying the transition to a market economy, themicro-evidence using the Russian Longitudinal Monitoring Survey is to thecontrary. There is no negative association between labour market uncertaintyor a labour market crisis and fertility, and frequently there is even apositive association. That is, women or couples who are themselves affectedby labour market crises often had a higher probability of having anotherchild in the period 1994–1996 than women/couples who were less affected bysuch crises. The lack of a negative association, and the presence of apositive association in many instances, is surprising from the standpoint ofeconomic fertility theory. It is also contrary to many explanatory theoriesabout the recent fertility decline in Central and Eastern European countriesthat are built on a more or less direct connection between the labour marketor an economic crisis and low fertility. [ABSTRACT FROM AUTHOR]

This paper uses the 1698 Slavonian census to illuminate features of social organization and productive activity of an eastern European population under the New Feudalism of the 17th century. In particular we investigate the ability of community or kinship networks to provide substitutes for missing markets in securities and production factors. It is found that kinship networks increase the efficiency of agricultural production by facilitating the exchange of oxen. This confirms contemporary reports that draft animals were the critical constraint to the expansion of agricultural output. We also find that kinship networks fail to reduce the variability of output through mutual harvest insurance. [ABSTRACT FROM AUTHOR]

In this paper we establish the asymptotic distribution of DeFries Fulker (1985) regression estimates for heritability and shared environmental influences with double-entry twin data. A simple formula to estimate the covariance matrix of the coefficients in DF-regressions is provided, and applications to simulated data and Danish twin data show that this method can substantially increase the statistical power of the analyses. We also provide an ‘efficient DF-analysis’ that yields more precise estimates when additional covariates are included among the explanatory variables. [ABSTRACT FROM AUTHOR]

A recent formula due to Bongaarts and Feeney allows us todisentangle tempo and quantum effects in changes of the totalfertility rate. This article applies the TFR adjustment toBulgaria, the Czech Republic, Hungary, Poland and Russia.Substantial differences between the adjusted and the observed TFRindicate important tempo effects in the recent decline offertility. Moreover, these five countries differ in the relativeimportance of tempo versus quantum effects, and in the periodwhen tempo effects are most relevant. We discuss the validity ofthe assumptions that underlie the usage of the formula and wetest whether age-period interactions may invalidate theseassumptions. [ABSTRACT FROM AUTHOR]

Behavior genetic designs and analysis can be used to address issues of central importance to demography. We use this methodology to document genetic influence on human fertility. Our data come from Danish twin pairs born from 1953 to 1959, measured on age at first attempt to get pregnant (FirstTry) and number of children (NumCh). Behavior genetic models were fitted using structural equation modeling and DF analysis. A consistent medium-level additive genetic influence was found for NumCh, equal across genders; a stronger genetic influence was identified for FirstTry, greater for females than for males. A bivariate analysis indicated significant shared genetic variance between NumCh and FirstTry. [ABSTRACT FROM AUTHOR]

Demographers have argued increasingly that social interaction is an important mechanism for understanding fertility behavior. Yet it is still quite uncertain whether social learning or social influence is the dominant mechanism through which social networks affect individuals' contraceptive decisions. In this paper we argue that these mechanisms can be distinguished by analyzing the density of the social network and its interaction with the proportion of contraceptive users among network partners. Our analyses indicate that social learning is most relevant with high market activity; in regions with only modest market activity, however, social influence is the dominant means by which social networks affect women's contraceptive use. [ABSTRACT FROM AUTHOR]

Bongaarts and Feeney have recently proposed an adjusted total fertility rate to disentangle tempo effects from changes in the quantum of fertility. We propose an extension to the Bongaarts and Feeney formula that includes variance effects: that is, changes in the variance of the fertility schedule over time. If these variance effects are ignored, the mean age at birth and the adjusted total fertility rate are biased. We provide approximations for these biases, and we extend the TFR adjustment to fertility schedules with changing variance. We apply our method to the Swedish baby boom and bust, and show that variance effects are important for evaluating the relative contributions of tempo and quantum effects to the fertility change from 1985 to 1995. [ABSTRACT FROM AUTHOR]

Binary and censored variables can lead to erroneous inferences about heritability in family studies if the dichotomous or censored nature of the dependent variable is not properly accounted for. The bivariate probit and tobit models proposed in this paper provide a unified approach to family studies with binary, ordered, and censored variables. Each model in this paper is derived from a similar latent-variable structure which can contain covariates that affect the expected value of the dependent variable, as well as genetic and shared environmental influences that lead to an association among related individuals. We apply the models to the fertility outcome and fertility motivations of Danish twins born 1953–1964 and find relevant genetic influences on the number of children as well as the desired timing of the first child. [ABSTRACT FROM AUTHOR]

This article presents information about a study which focuses on the persistent diversity in contraceptive practices across communities, or social strata while focusing on a proposed model of learning in social networks for modern fertility control. Understanding contraceptive choice is essential for improving women's reproductive health and for providing effective family planning services. Markets for contraceptive information are frequently absent and media may fail to convey the complex set of ideas and procedures involved in the adoption of fertility control. Faced with this market failure, women make contraceptive decisions based on information from early adopters in their social networks. Results of the study suggests that regional diversity and social stratification in contraceptive practices arise due to informal communications, rather than in-depth discussions about fertility control. The information shared among network partners is limited and there is unobserved heterogeneity with respect to women's attributes and characteristics. The qualitative choice model used in this study, yields the prediction that the probability of a woman adopting modem contraception equals the proportion of number of users in her social network.

Methanothrix soehngenii was found to contain five different cobamides when grown on vitamin B supplemented as well as vitamin B free media. In both cases, it was shown by HPLC-chromatography and UV/VIS spectroscopy, that α-5-methylbenzimidazolyl-β-cyanocobamide was the predominant cobamide, accounting for 27% and 23%, respectively, of the total corrinoid content. Vitamin B and α-5-hydroxybenzimidazolyl-β-cyanocobamide could also be detected in both cell batches in varying amounts. Cells grown on vitamin B free medium contained significantly more baseless cobamides, indicating biosynthesis of cobamides. [ABSTRACT FROM AUTHOR]

The objective of this work was to improve our understanding of the quantitative predictive capabilities of metatranscriptomics. To meet this objective, we investigated whether we can predict the activity level of a specific biochemical function based on the abundance of the corresponding gene transcript within measured community metatranscriptomes. In addition, we investigated the lower limit of a microorganism's abundance that still allows detection of its transcripts within a metatranscriptome and prediction of the activity levels of the enzyme encoded by the transcript. To do this, we amended an undefined microbial community with varying fractions of an Escherichia coli strain that can catalyze a specific transformation reaction for the herbicide atrazine. We observed a linear and proportional relationship between the activity level of the transformation reaction and the abundance of its associated encoding transcript down to an E. coli cell density of 0.05% of the population. [ABSTRACT FROM AUTHOR]

During the twentieth century, the global population has gone through unprecedented increases in economic and social development that coincided with substantial declines in human fertility and population growth rates. The negative association of fertility with economic and social development has therefore become one of the most solidly established and generally accepted empirical regularities in the social sciences. As a result of this close connection between development and fertility decline, more than half of the global population now lives in regions with below-replacement fertility (less than 2.1 children per woman). In many highly developed countries, the trend towards low fertility has also been deemed irreversible. Rapid population ageing, and in some cases the prospect of significant population decline, have therefore become a central socioeconomic concern and policy challenge. Here we show, using new cross-sectional and longitudinal analyses of the total fertility rate and the human development index (HDI), a fundamental change in the well-established negative relationship between fertility and development as the global population entered the twenty-first century. Although development continues to promote fertility decline at low and medium HDI levels, our analyses show that at advanced HDI levels, further development can reverse the declining trend in fertility. The previously negative development–fertility relationship has become J-shaped, with the HDI being positively associated with fertility among highly developed countries. This reversal of fertility decline as a result of continued economic and social development has the potential to slow the rates of population ageing, thereby ameliorating the social and economic problems that have been associated with the emergence and persistence of very low fertility. [ABSTRACT FROM AUTHOR]

Aerobic degradation experiments with the racemic mixtures of mecoprop and dichlorprop revealed that activated sludge collected from the aeration tank of a municipal waste water treatment plant degraded bothenantiomers of mecoprop and dichlorprop within 7 days, albeit in an enantioselective manner; the (S) enantiomers were preferentially degraded. Mecoprop, dichlorprop, and 2,4-D were completely metabolized under aerobic conditions, as shown by the 86-98% elimination of dissolved organic carbon. Under anaerobic conditions, the concentration of 2,4-D decreased exponentially with a first-order reaction rate constant of 0.24 per day and without a lag-phase. After an incubation time of 17 days, 2,4-D was completely removed. 2,4-Dichlorophenol was the main metabolite of anaerobic 2,4-D degradation; only traces of 4-chlorophenol were detected. In contrast, the chiral phenoxypropionic acid herbicides mecoprop and dichlorprop persisted under anaerobic conditions during 49 days of incubation. [ABSTRACT FROM AUTHOR]