Transit Surveys Research Articles

Public provision of employment support services to youth jobseekers

PurposeThe purpose of this paper is to investigate if public provision of employment support services to youth leads to reduced informality and increased wages in transition economies.Design/methodology/approachThe author uses the school-to-work transition data sets of the International Labor Organization for seven transition economies of Southeast Europe and the Commonwealth of Independent States. The author focuses on two econometric issues: the selectivity into informal employment and the endogeneity of the public employment support service provision with respect to informal employment and wages. The authors achieves identification by employing internal regressors which are uncorrelated with the product of heteroskedastic errors, a-la Lewbel (2012), as the author could not prove the external validity of the commonly used external instruments in similar contexts.FindingsResults suggest that the public provision of employment support services matters for relegating informal employment, but not for wages, in general. Placement in education or training programs is most powerful in reducing informal employment among the four different employment support services, while only advice for job search works positively for wages probably through enabling better match.Social implicationsIncreasing budget allocations, varying the array of public employment support measures, enhanced targeting, and advancement of the profiling system may significantly contribute to strengthening the public employment support service effect on youth employment in transition economies.Originality/valueThe paper brings a couple of novelties to the current literature. First, it is among the early papers dealing with the issue of informality, public employment support service and labor market prospects of youth in general in a rigorous manner. Second, it fills an important gap for transition economies which were less researched due to the long-lasting transition process as well due to data scarcity. Third, it utilizes the recently collected School-to-Work Transition Surveys (SWTS). Finally, and likely most importantly, it thoroughly addresses the issues of selectivity bias and endogeneity of PESS by utilizing a recent approach of Lewbel (2012) whereby internally generated variables are used as instruments. Hence, the paper accounts for the endogeneity stemming from unobservables in a novel manner, contrary to the common approaches in the literature based either on propensity score matching addressing selectivity on observables only, or relying on commonly used instruments in the labor market literature – mainly regional employment variables – whose external validity is easily disputed.

The Educational Consequences of Adolescent Childbearing and Union Formation in Brazil.

While Brazil has high rates of adolescent fertility for its below-replacement total fertility rate, we know little about the causal effects of adolescent childbearing and adolescent union formation for women's education. In this paper, we examine unique data from the 2013 School-to-Work Transitions Survey to address the consequences of adolescent childbearing and adolescent union formation on educational outcomes of Brazilian young women. We apply several analytical strategies to address the endogeneity between adolescent childbearing and educational outcomes. Our findings suggest that childbearing during the teenage years is detrimental to the educational attainment of Brazilian women, and that educational disadvantages persist once we take into account mother's selection into adolescent childbearing. The penalty for adolescent mothers ranges from -1.66 to -1.80 fewer years of schooling and from 41 to 35 percent difference in the probabilities of graduating from high school. Additional findings show that marital unions among adolescent mothers have a compounding role at further hindering women's educational progress. Combined, our findings suggest that young mothers, particularly those in a marital union, face additional layers of disadvantages, demonstrating that early family formation is a meaningful stratifier for women in an already highly-stratified society.

The Experience of Self-Employment Among Young People: An Exploratory Analysis of 28 Low- to Middle-Income Countries

Youth unemployment has become the global “wicked” policy issue for governments and multilateral agencies with many regions experiencing endemically high levels. In response, governments and international organizations have introduced more active labor market interventions to address youth unemployment. Self-employment and entrepreneurship programs are seen as the key mechanisms to reduce unemployment, welfare dependency, and poverty. We use the International Labour Organization’s 2012 School-to-Work Transition Survey from 28 developing countries to provide new evidence of young people’s experience of job quality and associated working conditions in self-employment. We find that self-employment is not necessarily a favorable employment status in terms of the economic and social benefits it provides for young people. In countries often characterized by limited formal employment opportunities, a large informal sector and depressed local labor markets, self-employment can be seen as the only realistic way many young people can generate an income. Entry into self-employment can be more accurately described as a pragmatic coping mechanism by the young person and their family to get by rather than as evidence of entrepreneurship and a pathway to get on in terms of social mobility and poverty alleviation. We find little evidence that young people are making utility-maximizing decisions concerning their employment status. Furthermore, we argue that if youth employment policies overlook the importance and role of kinship networks in the uptake of self-employment, they are likely to be even less effective than other programs to promote entrepreneurship.

Can Rocky Exoplanets with Rings Pose as Sub-Neptunes?

Abstract In our solar system, the presence of rings is exclusive to the gas giants, but is this the case for all planetary systems? In principle, it seems that rocky exoplanets could also have rings, which could be searched for by studying their subtle imprint on the ingress and egress of transits. Unfortunately, such effects are difficult to measure and require high-precision photometric and/or spectroscopic observations. At the most basic level though, the presence of rings would result in an increased transit depth that could be mistaken as an anonymously large radius. Motivated by this, I consider how a population of exoplanets with rings would impact radius measurements, focusing on Earth-like exoplanets. It is found that this population introduces an enhancement of inferred radii in the range of ∼2–3 R ⊕, not unlike the sub-Neptunes that have been identified in recent transit surveys. Whether rings can explain all or most sub-Neptunes seems difficult, since it would require a large fraction of rocky planets to have rings (≳40%) and/or a factor of ∼2–3 increase in the number of planets with radii ≲1.2 R ⊕. Even if rings cannot explain all sub-Neptunes, this work suggests that focusing on those planets currently classified as sub-Neptunes may be a good starting place for finding rocky planets with rings.

Happiness convergence in transition countries

The “transition happiness gap” has been one of the most robust findings in the literature on life satisfaction. Until very recently, scholars using various datasets have shown that residents of post-communist countries were significantly less satisfied with their lives than their counterparts in non-transition countries (controlling for income and other socio-economic characteristics). The literature has explained this finding by the great macroeconomic instability of the 1990s, by a substantial decrease in the quality and accessibility of public goods, by the major increase in inequality, and by the rapid depreciation of pre-transition human capital. All these factors were expected to subside over time – at least after the post-Great-Recession recovery. In this paper, we consider two most recent datasets – the third wave of the Life in Transition Survey (administered in 2015–16) and the 2010–2016 waves of the annual Gallup World Poll. We find that by 2016 the transition happiness gap had closed. This convergence has taken place both due to a “happiness recovery” in post-communist countries after the Great Recession and due to a decrease in life satisfaction in comparator countries in recent years. We also find that the convergence in life satisfaction was primarily driven by middle-income young, educated individuals, regardless of gender.

Measuring Model-independent Masses and Radii of Single-lined Eclipsing Binaries: Analytic Precision Estimates

Abstract We derive analytic estimates for the ability with which one can obtain precise, empirical stellar masses and radii via single-lined eclipsing binaries (EBs) in the era of Gaia and TESS. Including stars that host transiting substellar companions, such single-lined EBs already number in the hundreds from ground-based transit surveys and will comprise a major component of the science yield from the upcoming TESS mission. We explore the requirements for obtaining a given fractional precision on the masses and radii of single-lined EBs using primarily empirical means: radial velocity and eclipse measurements along with estimates of the primary’s (1) surface gravity from high-resolution spectroscopy; (2) radius inferred from parallax, effective temperature, and bolometric flux; or (3) surface gravity and density from asteroseismology. We then compare these requirements to the precision obtained from invoking stellar models or empirical relations. We show that, for a fiducial transiting hot Jupiter system, precise, accurate, and essentially model-independent mass and radius measurements for such single-lined EBs will be possible in the era of Gaia. These will be comparable in precision to those obtained with double-lined EBs. Moreover, the systems for which these methods can be applied will vastly outnumber double-lined EBs, thereby possessing the potential to sample a more complete range of stellar types (such as M dwarfs); these systems will also, in many cases, be more amenable to precision metallicity and abundance determinations than are double-lined EBs.

East European Discontent

Rise of populist and right-wing tendencies in Eastern Europe has been linked to people’s increasing dissatisfaction with the economy and growing inequality. Using Life in Transition Survey, we examine East Europeans’ attitudes on these economic issues. In contrast to views that the 2008 economic crisis prompted dissatisfaction, we find that even before the crisis, East Europeans were not convinced that their economic situation was better at that point than in 1989. Our findings suggest that economic discontent in Eastern Europe has been increasing over decades, and is especially pronounced among the poor and minorities, indicating their increasing social exclusion.

The impact of economic crisis on civic attitudes

PurposeIn times of crisis, the deterioration of living standards may also have direct consequences on civic culture of people and become dangerous for the health of democracy. The purpose of this paper is to investigate the extent to which the recent economic crisis directly influences the civic attitudes in some European democracies focusing on two questions: how much does crisis exposure affect civic attitudes? And what is the role played by expected social mobility on this effect?Design/methodology/approachHypotheses are tested using data collected in the Western European countries included in the Life in Transition Survey II (France, Germany, Italy, Sweden and UK). To analyze the civic consequences of crisis exposure and to evaluate the moderating role of expected social mobility, multivariate regressions are conducted. The statistical analysis is performed using the Stata software.FindingsThe findings show that economic crisis exposure significantly affects civic attitudes. The results confirm that higher crisis exposure is associated with lower civic attitudes. Additionally, the present research rules out the possibility that crisis exposure affects attitudes in a specific way, depending on the expected mobility valence.Social implicationsTo evaluate the moderating factors of the civic consequences of economic crises is important for both academic research and policymakers. Analyzing these mechanisms may lead to understand under which conditions it is possible to limit deterioration processes in democratic fabric of a society.Originality/valueThis paper sheds light on the importance of analyzing the negative civic effect of economic crisis and on the critical role that the fear of social downgrading plays in determining this effect.

Biases in Planet Occurrence Caused by Unresolved Binaries in Transit Surveys

Abstract Wide-field surveys for transiting planets, such as the NASA Kepler and TESS missions, are usually conducted without knowing which stars have binary companions. Unresolved and unrecognized binaries give rise to systematic errors in planet occurrence rates, including misclassified planets and mistakes in completeness corrections. The individual errors can have different signs, making it difficult to anticipate the net effect on inferred occurrence rates. Here, we use simplified models of signal-to-noise limited transit surveys to try and clarify the situation. We derive a formula for the apparent occurrence rate density measured by an observer who falsely assumes all stars are single. The formula depends on the binary fraction, the mass function of the secondary stars, and the true occurrence of planets around primaries, secondaries, and single stars. It also takes into account the Malmquist bias by which binaries are over-represented in flux-limited samples. Application of the formula to an idealized Kepler-like survey shows that for planets larger than 2 R ⊕, the net systematic error is of order 5%. In particular, unrecognized binaries are unlikely to be the reason for the apparent discrepancies between hot-Jupiter occurrence rates measured in different surveys. For smaller planets the errors are potentially larger: the occurrence of Earth-sized planets could be overestimated by as much as 50%. We also show that whenever high-resolution imaging reveals a transit host star to be a binary, the planet is usually more likely to orbit the primary star than the secondary star.

Automatic vetting of planet candidates from ground-based surveys: machine learning with NGTS

State of the art exoplanet transit surveys are producing ever increasing quantities of data. To make the best use of this resource, in detecting interesting planetary systems or in determining accurate planetary population statistics, requires new automated methods. Here we describe a machine learning algorithm that forms an integral part of the pipeline for the NGTS transit survey, demonstrating the efficacy of machine learning in selecting planetary candidates from multi-night ground based survey data. Our method uses a combination of random forests and self-organising-maps to rank planetary candidates, achieving an AUC score of 97.6% in ranking 12368 injected planets against 27496 false positives in the NGTS data. We build on past examples by using injected transit signals to form a training set, a necessary development for applying similar methods to upcoming surveys. We also make the autovet code used to implement the algorithm publicly accessible. autovet is designed to perform machine learned vetting of planetary candidates, and can utilise a variety of methods. The apparent robustness of machine learning techniques, whether on space-based or the qualitatively different ground-based data, highlights their importance to future surveys such as TESS and PLATO and the need to better understand their advantages and pitfalls in an exoplanetary context.

Unmasking the hidden NGTS-3Ab: a hot Jupiter in an unresolved binary system

We present the discovery of NGTS-3Ab, a hot Jupiter found transiting the primary star of an unresolved binary system. We develop a joint analysis of multi-colour photometry, centroids, radial velocity (RV) cross-correlation function (CCF) profiles and their bisector inverse slopes (BIS) to disentangle this three-body system. Data from the Next Generation Transit Survey (NGTS), SPECULOOS and HARPS are analysed and modelled with our new blendfitter software. We find that the binary consists of NGTS-3A (G6V-dwarf) and NGTS-3B (K1V-dwarf) at <1 arcsec separation. NGTS-3Ab orbits every P = 1.675 days. The planet radius and mass are R_planet = 1.48+-0.37 R_J and M_planet = 2.38+-0.26 M_J, suggesting it is potentially inflated. We emphasise that only combining all the information from multi-colour photometry, centroids and RV CCF profiles can resolve systems like NGTS-3. Such systems cannot be disentangled from single-colour photometry and RV measurements alone. Importantly, the presence of a BIS correlation indicates a blend scenario, but is not sufficient to determine which star is orbited by the third body. Moreover, even if no BIS correlation is detected, a blend scenario cannot be ruled out without further information. The choice of methodology for calculating the BIS can influence the measured significance of its correlation. The presented findings are crucial to consider for wide-field transit surveys, which require wide CCD pixels (>5 arcsec) and are prone to contamination by blended objects. With TESS on the horizon, it is pivotal for the candidate vetting to incorporate all available follow-up information from multi-colour photometry and RV CCF profiles.

Optical and Near-infrared Radial Velocity Content of M Dwarfs: Testing Models with Barnard’s Star

Abstract High-precision radial velocity (RV) measurements have been central in the study of exoplanets during the last two decades, from the early discovery of hot Jupiters, to the recent mass measurements of Earth-sized planets uncovered by transit surveys. While optical RV is now a mature field, there is currently a strong effort to push the technique into the near-infrared domain (chiefly Y, J, H, and K bandpasses) to probe planetary systems around late-type stars. The combined lower mass and luminosity of M dwarfs leads to an increased reflex RV signal for planets in the habitable zone compared to Sun-like stars. The estimates on the detectability of planets rely on various instrumental characteristics but also on a prior knowledge of the stellar spectrum. While the overall properties of M dwarf spectra have been extensively tested against observations, the same is not true for their detailed line profiles, which leads to significant uncertainties when converting a given signal-to-noise ratio to a corresponding RV precision as attainable on a given spectrograph. By combining archival CRIRES and HARPS data with ESPaDOnS data of Barnard’s star, we show that state-of-the-art atmosphere models over-predict the Y- and J-band RV content by more than a factor of ∼2, while under-predicting the H- and K-band content by half.

Comparative Analysis of Young People’s Access to the Labor Market in Benin and Togo: An Application of the Inequality of Opportunity Index

In low- and middle-income countries such as West African countries, access to youth labour market is characterized by significant inequalities. But it is rare to find in the context of the West African countries, empirical studies which have focused on inequalities of opportunity on the issue of young people's transition from school to work in Benin, Liberia and Togo. To fill this gap, we estimated the scope of the inequality of opportunities in access to youth labour market by countries and the factors that influence this access by using data from School to Work Transition Survey (SWTS). To achieve the objectives of this paper, we computed the Human Opportunity Index (HOI) using three indicators of access to youth labour market. The three indicators of access were: Occupied with a workweek (employment); has contract occupation (contract) and has work protected with insurance (insurance). We then examined circumstance variables and the individual’s characteristic contributions and differences across countries. The results show that inequality of opportunities varies within and across countries. The inequality of opportunity is much more pronounced in Benin for job opportunities (33.6), contract (40.8) and Liberia for the job opportunity with insurance (49.3). We note that the characteristics of parents contribute more to the inequality of opportunity in the access of young people to a job in Togo compared to the situation in Benin and Liberia. We find also that demographic factors contribute much more to the inequality in access to employment in Liberia (78.02%) compared to Benin (74.26%) and Togo (45.05%). The levels of inequality of opportunities as well as the average coverage and access rates shows that there are still more to do in ensuring equitable access to youth labour market in these countries.

Ground-based detection of G star superflares with NGTS

We present high cadence detections of two superflares from a bright G8 star (V = 11.56) with the Next Generation Transit Survey (NGTS). We improve upon previous superflare detections by resolving the flare rise and peak, allowing us to fit a solar flare inspired model without the need for arbitrary break points between rise and decay. Our data also enables us to identify substructure in the flares. From changing starspot modulation in the NGTS data we detect a stellar rotation period of 59 hours, along with evidence for differential rotation. We combine this rotation period with the observed \textit{ROSAT} X-ray flux to determine that the star's X-ray activity is saturated. We calculate the flare bolometric energies as $5.4^{+0.8}_{-0.7}\times10^{34}$ and $2.6^{+0.4}_{-0.3}\times10^{34}$ erg and compare our detections with G star superflares detected in the \textit{Kepler} survey. We find our main flare to be one of the largest amplitude superflares detected from a bright G star. With energies more than 100 times greater than the Carrington event, our flare detections demonstrate the role that ground-based instruments such as NGTS can have in assessing the habitability of Earth-like exoplanets, particularly in the era of \textit{PLATO}.

Rotation-Activated and Cooperative Zipping Characterize Class I Viral Fusion Protein Dynamics

Class I viral fusion proteins are α-helical proteins that facilitate membrane fusion between viral and host membranes through large conformational transitions. Although prefusion and postfusion crystal structures have been solved for many of these proteins, details about how they transition between these states have remained elusive. This work presents the first, to our knowledge, computational survey of transitions between pre- and postfusion configurations for several class I viral fusion proteins using structure-based models to analyze their dynamics. As suggested by their structural similarities, all proteins share common mechanistic features during their transitions that can be characterized by a diffusive rotational search followed by cooperative N- and C-terminal zipping. Instead of predicting a stable spring-loaded intermediate, our model suggests that helical bundle formation is mediated by N- and C-terminal interactions late in the transition. Shared transition features suggest a global mechanism in which fusion is activated by slow protein-core rotation.

Is Informal Job Experience of Youth Undermining their Labor-Market Prospects in Transition Economies?

The objective of the paper is to investigate if previous informal employment experience of youth affects later labor-market outcomes in transition economies. We consider the effects on employment, decent job and wages. Some theories suggest that previous informal job experience may extend informality later and negatively impact decent employment and wages, while others argue that informal jobs may provide training, networks and working attitudes to young workers hence improving their formal employment and wage potential. We rely on the newly-produced School to Work Transition Surveys for seven transition economies of Southeast Europe and the Commonwealth of Independent States. Our results robustly suggest that early informality of youth is negative for the later labor-market outcomes. However, for the wage, there is limited evidence that the negative effect potentially turns positive for long informal job experiences. The negative effect of informal job on later outcomes is stronger for females, while any differences between the two regions of transition economies are neither systematic nor robust.

Low-mass eclipsing binaries in the WFCAM Transit Survey: the persistence of the M-dwarf radius inflation problem

We present the characterization of 5 new short-period low-mass eclipsing binaries from the WFCAM Transit Survey. The analysis was performed by using the photometric WFCAM J-mag data and additional low- and intermediate-resolution spectroscopic data to obtain both orbital and physical properties of the studied sample. The light curves and the measured radial velocity curves were modeled simultaneously with the JKTEBOP code, with Markov chain Monte Carlo simulations for the error estimates. The best-model fit have revealed that the investigated detached binaries are in very close orbits, with orbital separations of $2.9 \leq a \leq 6.7$ $R_{\odot}$ and short periods of $0.59 \leq P_{\rm orb} \leq 1.72$ d, approximately. We have derived stellar masses between $0.24$ and $0.72$ $M_{\odot}$ and radii ranging from $0.42$ to $0.67$ $R_{\odot}$. The great majority of the LMEBs in our sample has an estimated radius far from the predicted values according to evolutionary models. The components with derived masses of $M < 0.6$ $M_{\odot}$ present a radius inflation of $\sim$$9\%$ or more. This general behavior follows the trend of inflation for partially-radiative stars proposed previously. These systems add to the increasing sample of low-mass stellar radii that are not well-reproduced by stellar models. They further highlight the need to understand the magnetic activity and physical state of small stars. Missions like TESS will provide many such systems to perform high-precision radius measurements to tightly constrain low-mass stellar evolution models.

The challenge of youth employment in Asia: Lessons from four fast‐growing economies

AbstractThe situation of youth in relation to the labour market is a matter of serious concern for many governments, and an issue of increasing focus in international policy discussions. This paper draws on comparable school to work transition survey data to examine the nature of youth employment in four important and generally successful Asian economies that are relatively engaged in international trade, though to varying extents: Bangladesh, Cambodia, Nepal and Vietnam. In all four, many young people continue to be engaged in self‐employment or unpaid family work; while in some cases, this may reflect the lack of opportunities for wage work in the formal sector, often such outcomes may be positive choices on the part of the young people. The availability of formal jobs for young people varies across the four countries, with the extent and diversity of industrialisation or exports being one important factor, as well as the level of education. In Vietnam, the country most advanced in these areas, the availability of formal jobs is significantly greater than in the other countries and is large on an international scale, while in Bangladesh and Cambodia, the textiles and garment sectors have played an important role in creating formal work opportunities, especially for females.

Hierarchical Bayesian calibration of tidal orbit decay rates among hot Jupiters

Transiting hot Jupiters occupy a wedge-shaped region in the mass ratio-orbital separation diagram. Its upper boundary is eroded by tidal spiral-in of massive, close-in planets and is sensitive to the stellar tidal dissipation parameter $Q_s'$. We develop a simple generative model of the orbital separation distribution of the known population of transiting hot Jupiters, subject to tidal orbital decay, XUV-driven evaporation and observational selection bias. From the joint likelihood of the observed orbital separations of hot Jupiters discovered in ground-based wide-field transit surveys, measured with respect to the hyperparameters of the underlying population model, we recover narrow posterior probability distributions for $Q_s'$ in two different tidal forcing frequency regimes. We validate the method using mock samples of transiting planets with known tidal parameters. We find that $Q_s'$ and its temperature dependence are retrieved reliably over five orders of magnitude in $Q_s'$. A large sample of hot Jupiters from small-aperture ground-based surveys yields $\log_{10} Q_s'=(8.26\pm 0.14)$ for 223 systems in the equilibrium-tide regime. We detect no significant dependence of $Q_s'$ on stellar effective temperature. A further 19 systems in the dynamical-tide regime yield $\log_{10} Q_s'=7.3\pm 0.4$, indicating stronger coupling. Detection probabilities for transiting planets at a given orbital separation scale inversely with the increase in their tidal migration rates since birth. The resulting bias towards younger systems explains why the surface gravities of hot Jupiters correlate with their host stars' chromospheric emission fluxes. We predict departures from a linear transit-timing ephemeris of less than 4 seconds for WASP-18 over a 20-year baseline.

Local governance and occupational choice among young people: First evidence from Vietnam

Using data from the School-to-Work Transition Surveys 2015 (SWTS 2015), the Enterprise Census data in 2014 (ECD 2014), and the Provincial Competitiveness Index 2014 (PCI 2014), this paper examines for the first time the effect of individual and family characteristics, firm agglomeration, and the quality of labour training (provided by provincial governments) on occupational choice among young people in Vietnam. Interestingly, we find that women were more likely than men to have better jobs, even after controlling for all other variables in the models. Higher levels of education were the most important factor in choosing non-manual jobs, while family background (as measured by the father's occupation) plays a significant role in explaining young people's occupational choice. More importantly, it was found that the quality of labour training increases young people's chances of gaining better jobs. In addition, living in urban areas, the provincial GDP per capita, and firm agglomeration were also found to improve the probability of youth choosing better jobs.