The Dynamic Effects of Skilled Labour Targeting in Immigration Programs

We consider the impact of the recent trend in immigration policies towards selecting migrants on the basis of skills. The analysis uses an inter-temporal general equilibrium model with endogenous skill formation. The model is calibrated to a steady state benchmark that represents Australia in 2000-2001. We then consider the impact of the increase in skilled migrants of approximately 20 thousand per year, which corresponds to the increase in flows of migrant Professionals in Australia since 2000. We find that this generates substantial crowding out of the higher Education sector in Australia. Moreover we show that, when this shock is anticipated as a permanent policy change, there is very little net increase in the stock of skilled labour due to falling student enrollments of 12%. Paradoxically, in this case, the decline in students increases the number of unskilled workers in the economy such that the ratio skilled to unskilled workers in the economy actually falls and the skill premium increases.Immigration; Human Capital; Computable General Equilibrium Models

Dynamic Adjustments to Terms of Trade Shocks: The USA Productivity Boom and Australia

How has the USA’s “new economy” productivity boom affected Australia? We consider this question using a dynamic multi-sector growth model of the Australian and USA economies. We find that productivity growth in the USA durables sector generates small but important gains to Australia. We find that the transmission of growth is generated through increased export demand for Agriculture. Consequently we find that the USA’s productivity growth tends to favour Australia’s traditional export sectors. Likewise it increases the relative demand for less skilled labour in Australia and reduces the demand for skilled labour and higher education.Terms of Trade; Productivity; Economic Growth; Human Capital; Computable General Equilibrium Models

Dynamic Gains and Market Access Insurance: Another look at the AUSFTA

We use a dynamic computable general equilibrium model to revisit the dynamic benefits of the Australia-USA Free Trade Agreement and, in particular, to evaluate the insurance value of this agreement in the face of regional and global trade wars. The insurance benefits are quantified by comparing the status quo against alternative scenarios where some or all regions raise tariffs by 10 percent, both permanently and temporarily. These insurance gains are found to be as much as four times larger than the traditional status quo efficiency gains.Trade policy; Computable General Equilibrium; Human Capital; Dynamics

Analyzing Economy Wide Effects of Trade Liberalisation on Vietnam using a Dynamic Computable General Equilibrium Model

Since its reform process in the late 1980s, Vietnam has emerged as a rapidly growing economy with growth rates surpassing its more developed ASEAN neighbours. This paper aims to consider the economy wide impacts of trade liberalisation on Vietnam. We approach this by way of multi-region, multi-good, dynamic growth computable general equilibrium (DCGE) model. We find that trade liberalisation has caused a large fall in wage inequality thus increasing the welfare of unskilled workers in Vietnam. There is also evidence of a shift away from agriculture towards low-tech and intermediate manufacturing sectors. Additionally, there are significant gains in terms of large physical and human capital accumulation.

The International Effects of China's Growth, Trade and Ecucation Booms

China’s international trade flows have increased by 500% since 1992, far outstripping GDP growth. Likewise tertiary education enrollments have increased by 300%. We simulate these changes using a multi-sector growth model of the Chinese and USA economies. A decade of trade biased growth in China is found to have a large effect on the USA economy – raising GDP approximately 3-4.5 percentage points. We also show that the trade bias in China’s growth accounts for more than half of the observed growth in tertiary enrolments in China. In contrast neutral growth has practically no effect on USA incomes or China’s stock of skilled labour. Finally the simulations reveal that China’s education boom per se has practically no long run impact on the USA economy. The results thus indicate that the pattern of productivity growth in exports sectors, as might be caused by falling trade costs, has been critical in transmitting benefits of Chinese growth to the world economy. They also point to an important link between falling trade costs and human capital formation.Economic Growth, China, Human Capital, Trade Costs

The Mean Ultraviolet Spectrum of a Representative Sample of Faint z~3 Lyman Alpha Emitters

We discuss the rest-frame ultraviolet emission line spectra of a large (~100) sample of low luminosity redshift z~3.1 Lyman alpha emitters (LAEs) drawn from a Subaru imaging survey in the SSA22 survey field. Our earlier work based on smaller samples indicated that such sources have high [OIII]/[OII] line ratios possibly arising from a hard ionising spectrum that may be typical of similar sources in the reionisation era. With optical spectra secured from VLT/VIMOS, we re-examine the nature of the ionising radiation in a larger sample using the strength of the high ionisation diagnostic emission lines of CIII]1909, CIV1549, HeII1640, and OIII]1661,1666 in various stacked subsets. Our analysis confirms earlier suggestions of a correlation between the strength of Ly-alpha and CIII] emission and we find similar trends with broad band UV luminosity and rest-frame UV colour. Using various diagnostic line ratios and our stellar photoionisation models, we determine both the gas phase metallicity and hardness of the ionisation spectrum characterised by xi_ion - the number of Lyman continuum photons per UV luminosity. We confirm our earlier suggestion that xi_ion is significantly larger for LAEs than for continuum-selected Lyman break galaxies, particularly for those LAEs with the faintest UV luminosities. We briefly discuss the implications for cosmic reionisation if the metal-poor intensely star-forming systems studied here are representative examples of those at much higher redshift.Comment: 15 pages, 9 figures. Accepted for publication in MNRA

Storing fungicides safely

Growers who stocked up on fungicides for the 2005 growing season due to the threat of Asian soybean rust will likely be facing fungicide storage issues this winter, especially since it is likely that most products cannot be returned. The good news is that most fungicides have a shelf life of at least two years--and probably longer--assuming they are stored correctly. Optimum storage conditions are cool, dry conditions, away from sunlight. Storage temperatures should not go below freezing; however, if a fungicide does freeze, then slowly thaw it out at room temperature

New Constraints on Cosmic Reionization from the 2012 Hubble Ultra Deep Field Campaign

Understanding cosmic reionization requires the identification and characterization of early sources of hydrogen-ionizing photons. The 2012 Hubble Ultra Deep Field (UDF12) campaign has acquired the deepest infrared images with the Wide Field Camera 3 aboard Hubble Space Telescope and, for the first time, systematically explored the galaxy population deep into the era when cosmic microwave background (CMB) data indicate reionization was underway. The UDF12 campaign thus provides the best constraints to date on the abundance, luminosity distribution, and spectral properties of early star-forming galaxies. We synthesize the new UDF12 results with the most recent constraints from CMB observations to infer redshift-dependent ultraviolet (UV) luminosity densities, reionization histories, and electron scattering optical depth evolution consistent with the available data. Under reasonable assumptions about the escape fraction of hydrogen-ionizing photons and the intergalactic medium clumping factor, we find that to fully reionize the universe by redshift z ~ 6 the population of star-forming galaxies at redshifts z ~ 7-9 likely must extend in luminosity below the UDF12 limits to absolute UV magnitudes of M UV ~ –13 or fainter. Moreover, low levels of star formation extending to redshifts z ~ 15-25, as suggested by the normal UV colors of z ≃ 7-8 galaxies and the smooth decline in abundance with redshift observed by UDF12 to z ≃ 10, are additionally likely required to reproduce the optical depth to electron scattering inferred from CMB observations

Most Americans are now opposed to laws against interracial marriage, but their behavior does not yet reflect these attitudes

Recent decades have seen a dramatic fall in the number of people that support laws which prohibit interracial marriages, and an increase in the number of these marriages. But why does the rate of interracial marriages remain so low, when compared to same-race marriages? Using national data from the past three decades, Ginny E. Garcia, Richard Lewis Jr., and Joanne Ford-Robertson show that while attitudes towards interracial marriages have changed, many groups still have negative attitudes towards Black-White unions. They find that those who perceive social and economic competition with Blacks, such as those with lower levels of education, were more likely to support laws that prohibit interracial marriages and engage in behaviors that prevent Black’s wider participation in society

The Lyman Continuum Escape Survey: Ionizing Radiation from [O III]-Strong Sources at a Redshift of 3.1

We present results from the LymAn Continuum Escape Survey (LACES), a Hubble Space Telescope (HST) program designed to characterize the ionizing radiation emerging from a sample of Lyman alpha emitting galaxies at redshift $z\simeq 3.1$. As many show intense [O III] emission characteristic of $z>6.5$ star-forming galaxies, they may represent valuable low redshift analogs of galaxies in the reionization era. Using HST Wide Field Camera 3 / UVIS $F336W$ to image Lyman continuum emission, we investigate the escape fraction of ionizing photons in this sample. For 61 sources, of which 77% are spectroscopically confirmed and 53 have measures of [O III] emission, we detect Lyman continuum leakage in 20%, a rate significantly higher than is seen in individual continuum-selected Lyman break galaxies. We estimate there is a 98% probability that $\leq 2$ of our detections could be affected by foreground contamination. Fitting multi-band spectral energy distributions (SEDs) to take account of the varying stellar populations, dust extinctions and metallicities, we derive individual Lyman continuum escape fractions corrected for foreground intergalactic absorption. We find escape fractions of 15 to 60% for individual objects, and infer an average 20% escape fraction by fitting composite SEDs for our detected samples. Surprisingly however, even a deep stack of those sources with no individual $F336W$ detections provides a stringent upper limit on the average escape fraction of less than 0.5%. We examine various correlations with source properties and discuss the implications in the context of the popular picture that cosmic reionization is driven by such compact, low metallicity star-forming galaxies.Comment: 26 pages, 16 figures, accepted for publication in Ap