Modelling the location of self-employed workers in urban areas

In this article, we develop an urban model for self-employment where leisure and effort at work are complementary. Our model shows that unemployment tends to be concentrated far from business districts, in contrast to employment and self-employment. The self-employed tend to live closer to workplaces than do the employed, as commuting affects productivity and thus earnings. We use the American Time Use Survey to test the model and find that employment and self-employment are negatively related to commuting, in comparison to unemployment, while self-employment is associated with shorter commutes, giving support to the theoretical background

The abundance of 28Si32S, 29Si32S, 28Si34S, and 30Si32S in the inner layers of the envelope of IRC+10216

We present high spectral resolution mid-IR observations of SiS towards the C-rich AGB star IRC+10216 carried out with the Texas Echelon-cross-Echelle Spectrograph mounted on the NASA Infrared Telescope Facility. We have identified 204 ro-vibrational lines of 28Si32S, 26 of 29Si32S, 20 of 28Si34S, and 15 of 30Si32S in the frequency range 720-790 cm-1. These lines belong to bands v=1-0, 2-1, 3-2, 4-3, and 5-4, and involve rotational levels with Jlow<90. About 30 per cent of these lines are unblended or weakly blended and can be partially or entirely fitted with a code developed to model the mid-IR emission of a spherically symmetric circumstellar envelope composed of expanding gas and dust. The observed lines trace the envelope at distances to the star <35R* (~0.7 arcsec). The fits are compatible with an expansion velocity of 1+2.5(r/R*-1) km/s between 1 and 5R*, 11 km/s between 5 and 20R*, and 14.5 km/s outwards. The derived abundance profile of 28Si32S with respect to H2 is 4.9e-6 between the stellar photosphere and 5R*, decreasing linearly to 1.6e-6 at 20R* and to 1.3e-6 at 50R*. 28Si32S seems to be rotationally under LTE in the region of the envelope probed with our observations and vibrationally out of LTE in most of it. There is a red-shifted emission excess in the 28Si32S lines of band v=1-0 that cannot be found in the lines of bands v=2-1, 3-2, 4-3, and 5-4. This excess could be explained by an enhancement of the vibrational temperature around 20R* behind the star. The derived isotopic ratios 28Si/29Si, and 32S/34S are 17 and 14, compatible with previous estimates.Comment: 11 pages, 5 figures, and 4 tables. Accepted for publication in MNRA

Commuting time and sickness absence of US workers

This paper analyzes the relationship between commuting time and days of sickness absence of US workers. Using data from the Panel Study of Income Dynamics for the years 2011 to 2017, we find that a 1% increase in the daily commute of workers is associated with an increase of 0.018 and 0.027% in the days of sickness absence per year of male and female workers, respectively. These results are robust for women when sample selection, missing variables, and health status are explored. Further exploration of this relationship shows that the positive relationship between commuting and sickness absence is concentrated in urban areas only, and is present in the intensive margin (hours) for men and the extensive margin (participation) for women. By uncovering how commuting time is related to sickness absenteeism, we contribute to the literature on the negative correlation between commuting and workers’ health and well-being

The intergenerational correlation of employment in Europe: a cross-country analysis

We analyse the long-run intergenerational correlation of employment in Europe, providing cross-country evidence. Using the 2011 special module on Intergenerational Transmission, from the European Union Statistics on Income and Living Conditions (EU-SILC), we analyse the correlation between the current employment status of respondents, and that of their parents when respondents were 14 years old, in nine European countries. Estimates show that the intergenerational correlation of employment varies across countries and by gender, and is, in most cases, small or non-statistically significant

The Abundance of SiC2 in Carbon Star Envelopes: Evidence that SiC2 is a gas-phase precursor of SiC dust

Silicon carbide dust is ubiquitous in circumstellar envelopes around C-rich AGB stars. However, the main gas-phase precursors leading to the formation of SiC dust have not yet been identified. The most obvious candidates among the molecules containing an Si--C bond detected in C-rich AGB stars are SiC2, SiC, and Si2C. We aim to study how widespread and abundant SiC2, SiC, and Si2C are in envelopes around C-rich AGB stars and whether or not these species play an active role as gas-phase precursors of silicon carbide dust in the ejecta of carbon stars. We carried out sensitive observations with the IRAM 30m telescope of a sample of 25 C-rich AGB stars to search for emission lines of SiC2, SiC, and Si2C in the 2 mm band. We performed non-LTE excitation and radiative transfer calculations based on the LVG method to model the observed lines of SiC2 and to derive SiC2 fractional abundances in the observed envelopes. We detect SiC2 in most of the sources, SiC in about half of them, and do not detect Si2C in any source, at the exception of IRC +10216. Most of these detections are reported for the first time in this work. We find a positive correlation between the SiC and SiC2 line emission, which suggests that both species are chemically linked, the SiC radical probably being the photodissociation product of SiC2 in the external layer of the envelope. We find a clear trend in which the denser the envelope, the less abundant SiC2 is. The observed trend is interpreted as an evidence of efficient incorporation of SiC2 onto dust grains, a process which is favored at high densities owing to the higher rate at which collisions between particles take place. The observed behavior of a decline in the SiC2 abundance with increasing density strongly suggests that SiC2 is an important gas-phase precursor of SiC dust in envelopes around carbon stars.Comment: Published in A&A. 16 pages and 10 figure

Sustainable commuting: Results from a social approach and international evidence on carpooling

Sustainable commuting (SC) usually refers to environmentally friendly travel modes, such as public transport (bus, tram, subway, light rail), walking, cycling, and carpooling. The double aim of the paper is to summarize relevant prior results in commuting from a social approach, and to provide new, international empirical evidence on carpooling as a specific mode of sustainable commuting. The literature shows that certain socio-demographic characteristics clearly affect the use of non-motorized alternatives, and compared to driving, well-being is greater for those using active travel or public transport. Additionally, this paper analyzes the behavior of carpooling for commuting, using ordinary least squares (OLS) models, which have been estimated from the Multinational Time Use Study (MTUS) for the following countries: Bulgaria, Canada, Spain, Finland, France, Hungary, Italy, South Korea, the United Kingdom, and the United States. Results indicate that carpooling for commuting is not habitual for workers, as less than 25% of the total time from/to work by car is done with others on board. With respect to the role of the socio-demographic characteristics of individuals, our evidence indicates that age, gender, education, being native, and household composition may have a cross-country, consistent relationship with carpooling participation. Given that socializing is the main reason for carpooling, in the current COVID-19 pandemic, carpooling may be decreasing and, consequently, initiatives have been launched to show that carpooling is a necessary way to avoid crowded modes of transport. Thus, the development of high-occupancy-vehicle (HOV) lanes by local authorities can increase carpooling, and draw attention to the economic and environmental benefits of carpooling for potential users

Intergenerational Transmission of Entrepreneurial Activity in Spanish Families

This paper empirically analyzes the existence of intergenerational transmission of entrepreneurial activity, from parents to children within Spanish families. We used data from the Survey of Household Finances (Bank of Spain) for the years 2002, 2005, 2008, 2011, and 2014, which allowed us to identify entrepreneurs as self-employed workers. The entrepreneurial activity of individuals was studied as a function of individual and parental demographics and labor characteristics. We found a significant correlation between the entrepreneurial activity of parents and children, which appeared to have remained unchanged during the last decade and the years of the economic crisis. Furthermore, the intergenerational transmission of occupation from parents to children was stronger for entrepreneurs than for employees

Clues to NaCN formation

ALMA is providing us essential information on where certain molecules form. Observing where these molecules emission arises from, the physical conditions of the gas, and how this relates with the presence of other species allows us to understand the formation of many species, and to significantly improve our knowledge of the chemistry that occurs in the space. We studied the molecular distribution of NaCN around IRC +10216, a molecule detected previously, but whose origin is not clear. High angular resolution maps allow us to model the abundance distribution of this molecule and check suggested formation paths. We modeled the emission of NaCN assuming local thermal equilibrium (LTE) conditions. These profiles were fitted to azimuthal averaged intensity profiles to obtain an abundance distribution of NaCN. We found that the presence of NaCN seems compatible with the presence of CN, probably as a result of the photodissociation of HCN, in the inner layers of the ejecta of IRC +10216. However, similar as for CH 3 CN, current photochemical models fail to reproduce this CN reservoir. We also found that the abundance peak of NaCN appears at a radius of 3 x 10 15 cm, approximately where the abundance of NaCl, suggested to be the parent species, starts to decay. However, the abundance ratio shows that the NaCl abundance is lower than that obtained for NaCN. We expect that the LTE assumption might result in NaCN abundances higher than the real ones. Updated photochemical models, collisional rates, and reaction rates are essential to determine the possible paths of the NaCN formation.Comment: 7 pages, 10 figures. Accepted for publication in A&A letter

Central limit theorem for crossings in randomly embedded graphs

We consider the number of crossings in a random embedding of a graph, $G$, with vertices in convex position. We give explicit formulas for the mean and variance of the number of crossings as a function of various subgraph counts of $G$. Using Stein's method and size-bias coupling, we prove an upper bound on the Kolmogorov distance between the distribution of the number of crossings and a standard normal random variable. As an application, we establish central limit theorems, along with convergence rates, for the number of crossings in random matchings, path graphs, cycle graphs, and the disjoint union of triangles.Comment: 18 pages, 5 figures. This is a merger of arXiv:2104.01134 and arXiv:2205.0399