Polytropic models of filamentary interstellar clouds - I. Structure and stability

The properties of filamentary interstellar clouds observed at sub-millimetre wavelengths, especially by the Herschel Space Observatory, are analysed with polytropic models in cylindrical symmetry. The observed radial density profiles are well reproduced by negative-index cylindrical polytropes with polytropic exponent $1/3\lesssim \gamma_{\rm p} \lesssim 2/3$ (polytropic index $-3\lesssim n \lesssim -3/2$), indicating either external heating or non-thermal pressure components. However, the former possibility requires unrealistically high gas temperatures at the filament's surface and is therefore very unlikely. Non-thermal support, perhaps resulting from a superposition of small-amplitude Alfv\'en waves (corresponding to $\gamma_{\rm p}=1/2$), is a more realistic possibility, at least for the most massive filaments. If the velocity dispersion scales as the square root of the density (or column density) on the filament's axis, as suggested by observations, then polytropic models are characterised by a uniform width. The mass per unit length of pressure-bounded cylindrical polytropes depends on the conditions at the boundary and is not limited as in the isothermal case. However, polytropic filaments can remain stable to radial collapse for values of the axis-to-surface density contrast as large as the values observed only if they are supported by a non-isentropic pressure component.Comment: 9 pages, 4 figures. Accepted for publication in MNRA

In the name of the Father: marriage and intergenerational mobility in the United States, 1850-1930

This paper constructs a continuous and consistent measure of intergenerational mobility in the United States between 1850 and 1930 by linking individuals with the same first name across pairs of decennial Censuses. One of the advantages of this methodology is that it allows to calculate intergenerational correlations not only between fathers and sons, but also between fathers-in-law and sons-in-law, something that is typically not possible with historical data. Thus, the paper sheds light on the role of marriage in the intergenerational transmis- sion of economic status from a historical perspective. We find that the father-son correlation in economic status grows throughout the period, but is consistently lower than the correlation between fathers-in-law and sons-in-law. The gap declines over time, and seems to have closed by the end of the period. We present a simple model of investment in human capital, marital sorting and intergenerational mobility that can rationalize the ?ndings

In the name of the son (and the daughter): intergenerational mobility in the United States, 1850-1940

This paper estimates historical intergenerational elasticities between fathers and children of both sexes in the United States using a novel empirical strategy. The key insight of our approach is that the information about socioeconomic status conveyed by first names can be used to create pseudo-links across generations. We find that both father-son and father-daughter elasticities were flat during the nineteenth century, increased sharply between 1900 and 1920, and declined slightly thereafter. We discuss the role of regional disparities in economic development, trends in inequality and returns to human capital, and the marriage market in explaining these patterns

Markets and Geographical Indications of Origin: Synthesis of terra madre gathering and e-forum

Geographic Indications (GIs) such as Darjeeling Tea, Pampas meat, Basmati rice, and Parmigiano cheese embody unique expressions of culture, tradition, and place. This 6 page summary of the Main Themes of Discussion by the Terra Madre conference participants and the E-Forum departs from the premise that Geographical Indications can be an exceptional opportunity to utilize the power of the market to recognize and reward the products and services that convey particular traditions and uniqueness of culture and place. They also offer powerful rural development opportunities at the broad territorial level. Yet, some GIs succeed notably while others fail miserably. This brief document synthesizes the shared practical experiences and explores common and identifiable reasons why some GIs succeed and others fail.Terra Madre; Slow Food; local; Denominations of Origin; appelation;Rural Development; Cultural and Territorial Identity;

Three-generation mobility in the United States, 1850-1940: the role of maternal and paternal grandparents

This paper estimates intergenerational elasticities across three generations in the United States in the late 19th and early 20th centuries, exploring how maternal and paternal grandfathers predict the economic status of their grandsons and granddaughters. We document that the relationship between the income of grandparents and grandchildren differs by gender. The socio-economic status of grandsons is more strongly associated with the status of paternal grandfathers than maternal grandfathers. The status of maternal grandfathers is more strongly correlated with the status of granddaughters than grandsons, while the opposite is true for paternal grandfathers. We argue that the findings can be rationalized by a model of gender-specific intergenerational transmission of traits and imperfect assortative mating.Accepted manuscrip

Effect of sensitization on the electrochemical properties of nanostructured NiO

Screen-printed NiO electrodes were sensitized with 11 different dyes and the respective electrochemical properties were analyzed in a three-electrode cell with the techniques of cyclic voltammetry and electrochemical impedance spectroscopy. The dye sensitizers of NiO were organic molecules of different types (e.g., squaraines, coumarins, and derivatives of triphenyl-amines and erythrosine B), which were previously employed as sensitizers of the same oxide in dye-sensitized solar cells of p-type (p-DSCs). Depending on the nature of the sensitizer, diverse types of interactions occurred between the immobilized sensitizer and the screen-printed NiO electrode at rest and under polarization. The impedance data recorded at open circuit potential were interpreted in terms of two different equivalent circuits, depending on the eventual presence of the dye sensitizer on the mesoporous electrode. The fitting parameter of the charge transfer resistance through the electrode/electrolyte interface varied in accordance to the differences of the passivation action exerted by the various dyes against the electrochemical oxidation of NiO. Moreover, it has been observed that the resistive term RCT associated with the process of dark electron transfer between the dye and NiO substrate is strictly correlated to the overall efficiency of the photoconversion () of the corresponding p-DSC, which employs the same dye-sensitized electrode as photocathode

A land of opportunity no more: poor intergenerational mobility in the US is a feature of both the past and present.

In the past, concerns about inequality were tempered by the perception that people had a high degree of economic mobility. But how has intergenerational mobility changed in the US? In new research which uses census data on names and occupational income to examine social mobility between 1850 and 1940, Claudia Olivetti and Daniele Paserman find that intergenerational mobility was high in the 19th Century, then fell sharply between 1900 and 1920, and began to improve somewhat after that. They argue that these changes in economic mobility were influenced by regional differences in economic development and fluctuations in income and wealth inequalit

Polytropic models of filamentary interstellar clouds -II. Helical magnetic fields

We study the properties of magnetised cylindrical polytropes as models for interstellar filamentary clouds, extending the analysis presented in a companion paper (Toci & Galli 2014a). We formulate the general problem of magnetostatic equilibrium in the presence of a helical magnetic field, with the aim of determining the degree of support or compression resulting from the magnetisation of the cloud. We derive scale-free solutions appropriate to describe the properties of the envelopes of filaments at radii larger than the flat-density region. In these solutions, the polytropic exponent determines the radial profiles of the density and the magnetic field. The latter decreases with radius less steeply than the density, and field lines are helices twisted over cylindrical surfaces. A soft equation of state supports magnetic configurations that preferentially compress and confine the filament, whereas in the isothermal limit the field provides support. For each value of the polytropic exponent, the Lorentz force is directed outward or inward depending on whether the pitch angle is below or above some critical value which is a function of the polytropic exponent only.Comment: 8 pages, 1 figure. Accepted for publication in MNRA

The Shape of a Benedictine Monastery: The SaintGall Ontology (Extended Version)

We present an OWL 2 ontology representing the Saint Gall plan, one of the most ancient documents arrived intact to us, which describes the ideal model of a Benedictine monastic complex that inspired the design of many European monasteries.Comment: 10 pages, 10 figure