Where was the Iron Synthesized in Cassiopeia A?

We investigate the properties of Fe-rich knots on the east limb of the Cassiopeia A supernova remnant using observations with Chandra/ACIS and analysis methods developed in a companion paper. We use the fitted ionization age and electron temperature of the knots to constrain the ejecta density profile and the Lagrangian mass coordinates of the knots. Fe-rich knots which also have strong emission from Si, S, Ar, and Ca are clustered around mass coordinates q~0.35-0.4 in the shocked ejecta; for ejecta mass 2M_sun, this places the knots 0.7-0.8 M_sun out from the center (or 2-2.1 M_sun, allowing for a 1.3 M_sun compact object). We also find an Fe clump that is evidently devoid of line emission from lower mass elements, as would be expected if it were the product of alpha-rich freeze out; the mass coordinate of this clump is similar to those of the other Fe knots.Comment: submitted to ApJ, companion to Laming & Hwang; 25 pages, 6 figure

The Circumstellar Medium of Cassiopeia A Inferred from the Outer Ejecta Knot Properties

We investigate the effect of the circumstellar medium density profile on the X-ray emission from outer ejecta knots in the Cassiopeia A supernova remnant using the 1 Ms Chandra observation. The spectra of a number of radial series of ejecta knots at various positions around the remnant are analyzed using techniques similar to those devised in previous papers. We can obtain a reasonable match to our data for a circumstellar density profile proportional to r^-2 as would arise from the steady dense wind of a red supergiant, but the agreement is improved if we introduce a small (0.2-0.3 pc) central cavity around the progenitor into our models. Such a profile might arise if the progenitor emitted a fast tenuous stellar wind for a short period immediately prior to explosion. We review other lines of evidence supporting this conclusion. The spectra also indicate the widespread presence of Fe-enriched plasma that was presumably formed by complete Si burning during the explosion, possibly via alpha-rich freezeout. This component is typically associated with hotter and more highly ionized gas than the bulk of the O- and Si-rich ejecta.Comment: 12 pages, 3 figures; ApJ in pres

Models and Targets for the Pronunciation of English in Vietnam and Sweden

This paper aims to account for the factors that lie behind the choice of models and targets for the pronunciation of English by learners of English in Vietnam and in Sweden. English is the first foreign language in both Vietnam and in Sweden. English is used as a language of international communication in both settings. Swedish learners have much more exposure to spoken English than do Vietnamese learners and the Swedish language is more similar to English than is Vietnamese. These reasons, among others, explain why Swedish accents of English are typically considerably more intelligible than Vietnamese accents of English. Given that the majority of English speakers in the world are not native speakers, it is argued that the traditional learner target of approaching native speaker pronunciations is not appropriate for either group, but especially not for the Vietnamese learners. Instead maximal international intelligibility is a more useful target. To this end, learners need to be exposed to a variety of native and non-native models

Using Nigerian English in an international academic setting

This study examines the English pronunciation of a group of Nigerian students at a university in Sweden from the point of view of their intelligibility to two groups of listeners: 1) native speakers of English who are teachers at the university; 2) nonnative speakers of English who are teachers at the university. It is found that listeners who are accustomed to interacting with international students do better than those who are not, and that native speakers of English do no better or worse than non-native listeners. The conclusion is drawn that locally useful varieties of Nigerian English may not easily be used as for wider communication and that students preparing to study abroad would find it useful to gain access to a more widely intelligible variety

Integrating gender into index-based agricultural insurance: a focus on South Africa

Index insurance is an agricultural risk management tool that can provide a safety net for smallholder farmers experiencing climate risk. While uptake and scale-out of index insurance may be slow among smallholders, we can learn from experiences that demonstrate where crop insurance can protect smallholders’ livelihoods from climate risk. Integrating gender into climate risk management is necessary to ensure that the benefits of index insurance are experienced by both men and women. A dedicated intention to integrate gender may be required. Taking South Africa as a case study, the potential for gender-sensitive index insurance scale-out among smallholders is investigated

What can we learn about financial access from U.S. immigrants?

We find that wealthier and more educated immigrants are more likely to make use of basic banking services and other formal financial services. Holding these (and other) factors constant, we find immigrants from countries with more effective institutions are more likely to have a relationship with a bank and use formal financial markets more extensively. Institutional quality appears to be an important factor in both determining both the breadth and the depth of financial access. It can explain approximately 17 percent of the country-of- origin-level variation in bank account usage among immigrants in the U.S., after other characteristics, including wealth, education and income, are controlled for. Institutional quality is even more important for explaining more extensive participation in financial markets, accounting for 27 percent of the analogous variation. We examine various measures of institutional effectiveness and are careful to control for unobserved individual characteristics, including specifications with country fixed-effects.Immigrants ; Financial institutions ; Payment systems

Prospects for immigrant-native wealth assimilation: evidence from financial market participation

Because financial transactions are important for wealth accumulation, and rely on trust and confidence in institutions, the financial market behavior of immigrants can provide important insights into the assimilation process. Compared to the native-born, immigrants are less likely to own savings and checking accounts and these differences tend to persist over time. Our results suggest that a large share of the immigrant-native gap in financial market participation is driven by group differences in education, income, and geographic location. For a given immigrant, the likelihood of financial market participation decreases with higher levels of ethnic concentration in the metropolitan area.Financial institutions ; Immigrants ; Wealth

Does Female Schooling Reduce Fertility? Evidence from Nigeria

The literature generally points to a negative relationship between female education and fertility. Citing this pattern, policymakers have advocated educating girls and young women as a means to reduce population growth and foster sustained economic and social welfare in developing countries. This paper tests whether the relationship between fertility and education is indeed causal by investigating the introduction of universal primary education in Nigeria. Exploiting differences by region and age, the paper uses differences-in-differences and instrumental variables to estimate the role of education in fertility. The analysis suggests that increasing education by one year reduces fertility by 0.26 births.