This paper explores the impact of the introduction of the widely viewed MTV reality show 16 and Pregnant on teen childbearing. Our main analysis relates geographic variation in changes in teen ...childbearing rates to viewership of the show. We implement an instrumental variables (IV) strategy using local area MTV ratings data from a pre-period to predict local area 16 and Pregnant ratings. The results imply that this show led to a 4.3 percent reduction in teen births. An examination of Google Trends and Twitter data suggest that the show led to increased interest in contraceptive use and abortion.
Tidal channel networks mediate the exchange of water, nutrients and sediment between an estuary and marshes. Biology feeds back into channel morphodynamics through the influence of vegetation on both ...flow and the cohesive strength of channel banks. Determining how vegetation affects channel networks is essential in understanding the biological functioning of intertidal ecosystems and their ecosystem services. However, the processes that control the formation of an efficient tidal channel network remain unclear. Here we compare the channel networks of vegetated salt marshes in Massachusetts and the Venice Lagoon to unvegetated systems in the arid environments of the Gulf of California and Yemen. We find that the unvegetated systems are dissected by less efficient channel networks than the vegetated salt marshes. These differences in network geometry reflect differences in the branching and meandering of the channels in the network, characteristics that are related to the density of vegetation on the marsh.
This paper first documents trends in employment rates and then reviews what is known about the various factors that have been proposed to explain the decline in the overall employment-to-population ...ratio between 1999 and 2018. Population aging has had a large effect on the overall employment rate over this period, but within-age-group declines in employment among young- and prime-age adults also have played a central role. Among the factors with effects that we can quantify based on existing evidence, labor demand factors, in particular increased import competition from China and the penetration of robots into the labor market, are the most important drivers of observed within-group declines in employment. Labor supply factors, most notably increased participation in disability insurance programs, have played a less important but not inconsequential role. Increases in the real value of state minimum wages and in the share of individuals with prison records also have contributed modestly to the decline in the aggregate employment rate. In addition to the factors whose effects we roughly quantify, we identify a set of potentially important factors about which the evidence does not yet allow us to draw clear conclusions. These include the challenges associated with arranging child care, improvements in leisure technology, changing social norms, increased use of opioids, the growth in occupational licensing, and declining labor market fluidity. Our evidence-driven ranking of factors should be useful for guiding future discussions about the sources of decline in the aggregate employment-to-population ratio and consequently the likely efficacy of alternative policy approaches to increasing employment rates.
The retreat of coastal forests as sea level rises is well documented; however, the mechanisms which control this retreat vary with the physical and biological setting of the interface between tidal ...marsh and forest. Tidal flooding and saltwater intrusion as well as flooding and wind associated with storms can kill trees. Even if these processes do not kill stands, they may halt regeneration because seedlings are more sensitive to stress. We present a case study of a coastal pine forest on the Delmarva Peninsula, United States. This forest contains a persistent but nonregenerating zone of mature trees, the size of which is related to the sea level rise experienced since forest establishment. The transgression of coastal forest and shrub or marsh ecosystems is an ecological ratchet: sea-level rise pushes the regeneration boundary further into the forest while extreme events move the persistence boundary up to the regeneration boundary.
This project investigates how changes in Metropolitan Statistical Area (MSA)-level house prices affect household fertility decisions. Recognizing that housing is a major cost associated with child ...rearing, and assuming that children are normal goods, we hypothesize that an increase in house prices will have a negative price effect on current period fertility. This applies to both potential first-time homeowners and current homeowners who might upgrade to a bigger house with the addition of a child. On the other hand, for current homeowners, an increase in MSA-level house prices will increase home equity, leading to a positive effect on birth rates. Our results suggest that indeed, short-term increases in house prices lead to a decline in births among non-owners and a net increase among owners. The estimates imply that a $10,000 increase leads to a 5% increase in fertility rates among owners and a 2.4% decrease among non-owners. At the mean U.S. home ownership rate, these estimates imply that the net effect of a $10,000 increase in house prices is a 0.8% increase in current period fertility rates. Given underlying differences in home ownership rates, the predicted net effect of house price changes varies across demographic groups. In addition, we find that changes in house prices exert a larger effect on current period birth rates than do changes in unemployment rates.
•We investigate how metropolitan area house prices affect birth rates.•Increases in house prices exert a negative price effect on fertility rates.•For home owners, the price effect is offset by a positive “home equity effect”.•At the mean U.S. home ownership rate, the net effect of rising prices is positive.•House prices exert a larger effect on birth rates than unemployment rates.
Phenylketonuria (PKU) is an autosomal recessive inborn error of phenylalanine metabolism caused by deficiency in the enzyme phenylalanine hydroxylase that converts phenylalanine into tyrosine. If ...left untreated, PKU results in increased phenylalanine concentrations in blood and brain, which cause severe intellectual disability, epilepsy and behavioural problems. PKU management differs widely across Europe and therefore these guidelines have been developed aiming to optimize and standardize PKU care. Professionals from 10 different European countries developed the guidelines according to the AGREE (Appraisal of Guidelines for Research and Evaluation) method. Literature search, critical appraisal and evidence grading were conducted according to the SIGN (Scottish Intercollegiate Guidelines Network) method. The Delphi-method was used when there was no or little evidence available. External consultants reviewed the guidelines. Using these methods 70 statements were formulated based on the highest quality evidence available. The level of evidence of most recommendations is C or D. Although study designs and patient numbers are sub-optimal, many statements are convincing, important and relevant. In addition, knowledge gaps are identified which require further research in order to direct better care for the future.
Our understanding of how the gut microbiome interacts with its human host has been restrained by limited access to longitudinal datasets to examine stability and dynamics, and by having only a few ...isolates to test mechanistic hypotheses. Here, we present the Broad Institute-OpenBiome Microbiome Library (BIO-ML), a comprehensive collection of 7,758 gut bacterial isolates paired with 3,632 genome sequences and longitudinal multi-omics data. We show that microbial species maintain stable population sizes within and across humans and that commonly used 'omics' survey methods are more reliable when using averages over multiple days of sampling. Variation of gut metabolites within people over time is associated with amino acid levels, and differences across people are associated with differences in bile acids. Finally, we show that genomic diversification can be used to infer eco-evolutionary dynamics and in vivo selection pressures for strains within individuals. The BIO-ML is a unique resource designed to enable hypothesis-driven microbiome research.
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•The marsh growing season was shortened by hurricanes and recovered the following year.•The marsh area substantially decreased after hurricanes and rebounded in two years.•The ...intermediate and brackish marshes in the Breton Sound Basin showed the most damage.•Long-term nutrient enrichment may impair the marshes’ resilience against hurricanes.
Hurricanes pose an increasing threat to coastal environments as the intensity and severity of hurricanes are predicted to increase under the changing climate. Coastal wetlands are effective nature-based defenses of coastal cities against storms. However, the ecosystems themselves are also susceptible to the impacts of hurricanes, which are highly complex and not fully understood. Here we utilize multi-decadal satellite data archives (Landsat 1984–2014 and MODIS 2005–2015) and long-term coast-wide field-based environmental data (1978–2018) to investigate the impacts of hurricanes Katrina (2005), Gustav (2008), and Isaac (2012) on the coastal marshes in Louisiana, USA, where the hurricanes made landfall. While the hurricanes had immediate impacts on the marshes’ biomass and area at an ecosystem scale, general recovery was observed in the next one and two years. We also found that the most severe damage always occurred in the intermediate and brackish marshes of the Breton Sound basin, where the nitrogen concentration in the water was significantly higher compared to areas with less damage (P < 0.01). Because excess nutrient can reduce the marshes' root growth and degrade their root mat, we posit that the long-term nutrient enrichment in the area, which resulted from the diverted Mississippi River water, has increased the marshes’ susceptibility to hurricanes. The results highlight the resilience of coastal marsh ecosystems against hurricanes, but also underline the profound synergistic effects of climatic and anthropogenic factors on the sustainability of coastal ecosystems, which have important implications for coastal management under the current climate trend.
Summary
Background
The healthy microbiome protects against the development of Clostridium difficile infection (CDI), which typically develops following antibiotics. The microbiome metabolises primary ...to secondary bile acids, a process if disrupted by antibiotics, may be critical for the initiation of CDI.
Aim
To assess the levels of primary and secondary bile acids associated with CDI and associated microbial changes.
Methods
Stool and serum were collected from patients with (i) first CDI (fCDI), (ii) recurrent CDI (rCDI) and (iii) healthy controls. 16S rRNA sequencing and bile salt metabolomics were performed. Random forest regression models were constructed to predict disease status. PICRUSt analyses were used to test for associations between predicted bacterial bile salt hydrolase (BSH) gene abundances and bile acid levels.
Results
Sixty patients (20 fCDI, 19 rCDI and 21 controls) were enrolled. Secondary bile acids in stool were significantly elevated in controls compared to rCDI and fCDI (P < 0.0001 and P = 0.0007 respectively). Primary bile acids in stool were significantly elevated in rCDI compared to controls (P < 0.0001) and in rCDI compared to fCDI (P = 0.02). Using random forest regression, we distinguished rCDI and fCDI patients 84.2% of the time using bile acid ratios. Stool deoxycholate to glycoursodeoxycholate ratio was the single best predictor. PICRUSt analyses found significant differences in predicted abundances of bacterial BSH genes in stool samples across the groups.
Conclusions
Primary and secondary bile acid composition in stool was different in those with rCDI, fCDI and controls. The ratio of stool deoxycholate to glycoursodeoxycholate was the single best predictor of disease state and may be a potential biomarker for recurrence.
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