Endogenous migration in a two-country model with labor market frictions

We present a dynamic North-South model with search frictions and endogenous labor migration to study the long-run implications of labor factor mobility on labor market conditions and welfare. In the model, the high-TFP country (North) acts as the destination country for migration, while the low-TFP country (South) acts as the origin country. We prove that there always exists a unique steady-state equilibrium for the world economy, and find that a permanent increase in migration effort causes per capita income to rise in North and to fall in South. However, our simulations also show the existence of a job displacement effect in the host country that makes domestic employment fall in the long-run. In an extension of the baseline model, we test the long-run effects of a pro-employment protectionist policy of the destination country consisting in imposing a distortionary tax on the domestic firms hiring migrant workers. Our analysis shows that a positive tax rate on foreign employment can increase natives welfare, but only at the expense of losses in national production and employment. These results are robust across different degrees of substitutability between migrant and native workers

Information gathering, innovation and growth

In this paper we study the economic implications of IPR protection on corporate intelligence, R&D investment and economic growth. To accomplish this objective, we introduce trade secret and information leakage into a standard quality-ladder growth model and study the long-run implications of improving the privacy of firms' data. We find that reducing the set of practices of information gathering is more effective in protecting firms' privacy than strengthening trade secrets.Quality-improvement, R&D, information leakages, corporate intelligence, growth.

A Schumpeterian Growth Model with Heterogenous Firms

A common assumption in the Schumpeterian growth literature is that the innovation size is constant and identical across industries. This is in contrast with the empirical evidence which shows that: (i) the innovation size is far from being identical across industries; and (ii) the size distribution of profit returns from innovation is highly skewed toward the low value side, with a long tail on the high value side. In the present paper, we develop a Schumpeterian growth model that is consistent with this evidence. In particular, we assume that when a firm innovates, the size of its quality improvement is the result of a random draw from a Pareto distribution. This enables us to extend the class of quality-ladder growth models to encompass firm heterogeneity. We study the policy implications of this new set-up numerically and find that it is optimal to heavily subsidize R&D for plausible parameter values. Although it is optimal to tax R&D for some parameter values, this case only occurs when the steady-state rate of economic growth is very low.Schumpeterian Growth, R&D, optimal policy

A SCHUMPETERIAN GROWTH MODEL WITH EQUILIBRIUM UNEMPLOYMENT

We introduce efficiency-wage unemployment in a model of growth with endogenous technical change. Our research aim is twofold. First, we try to provide an analytically tractable model of growth with efficiency-wage unemployment that can be viewed as alternative to the standard models of growth and search unemployment. Second, we try to analyze the steady-state effects of some labor market policies on unemployment and growth. We find that a positive relationship between growth and unemployment exists and that the effectiveness of any labor market policy aimed at improving the performance of the labor market crucially depends on how individuals discount future income

Free labor mobility and indeterminacy in models of neoclassical growth

This paper establishes the conditions under which indeterminacy can occur in a Neoclassical growth model with international labor mobility. In the model, workers are supposed to move freely across countries without restrictions, and according to a Harris–Todaro mechanism that makes migration flows sensitive to differences among labor markets conditions. The paper shows that indeterminacy requires the marginal returns to immigrant labor to be diminishing, and no need for productivity externalities at a social level. It also shows that immigration quotas can serve it well to eliminate indeterminacy and stabilize final output

International Technology Gap and Technology Transmission: The Policy Implications

Income per capita differences have increased dramatically over the last fifty years. Many economists seem to recognize knowledge differences as the main factor in this worldwide economic performance divergence. Developing countries suffer significantly from lagging labour productivity and managerial efficiency related in part to the failure to adopt the latest technology or to update their labour force, and such an evidence has recently led to a huge debate about which channel is most effective in stimulating technology transfer and acquisition. In this paper we will review the policy tools that have been effective in reducing the international knowledge-gap between Developed and Developing countries, and the role played by institutional factors in accomplishing such an issue.J.e.l. codes: F4, K2, O2, O3 Economia Politica is covered by Social Sciences Citation Index, Social Scisearch, Journal Citation Reports/Social Sciences Edition (Thomson Reuters – ISI Web of Know ledge); Econlit/Journal of Economic Literature (AEA); Elsevier’s Abstracting & Indexing database – SCOPUS ISI Journal Citation Reports® Ranking 2009 Economics: 98/245. Impact Factor: 0,91

Investigating the contributions of leukocyte responses and kidney cell stress on Shiga- toxin pathogenesis

BACKGROUND: Shiga toxin (Stx)-producing enterohemorrhagic Escherichia coli (EHEC) are emerging food- and water- borne pathogens and a leading cause of acute renal failure in otherwise healthy children. Ribotoxic Shiga toxins are the primary virulence factors and are responsible for the potentially lethal EHEC complication of hemolytic uremic syndrome (HUS). HUS, defined clinically by microangiopathic hemolytic anemia, thrombocytopenia and thrombotic microangiopathy which contribute to acute kidney injury or renal failure, is associated with significant patient morbidity. No pathogen- or toxin- specific therapeutic exists, and antibiotic use is contraindicated. Understanding the molecular mechanisms of Stx toxicity could lead to the development of Stx specific therapies. HYPOTHESIS: Experimental evidence suggests a role for leukocytes in systemic Stx2 trafficking and in Stx2 mediated kidney pathology. Cell stress responses, such as the ER stress response and ribosomal stress response, are hypothesized to induce apoptosis, and ultimately cell death, contributing to kidney injury; however these processes have only been described in vitro. If leukocyte and kidney cell stress responses are playing significant roles in in vivo Stx2 kidney injury, then down-regulation of these processes may provide therapeutic benefit. RESULTS: Mice injected with Stx2 or infected with Stx2-producing bacteria developed lethal kidney injury as judged by biomarkers and histopathology. Experimentally induced leukopenia did not alter kidney injury in either model, but did cause striking increases in the intestinal bacterial colonization which was dependent on the presence of Stx2. No Stx binding capacity was observed for either murine or human leukocytes ex vivo. Transcriptional evidence of kidney ER stress and apoptotic biomarkers were observed in both models of Stx2-mediated kidney injury, but down-regulation of these processes did not yield therapeutic benefit. CONCLUSIONS: Contrary to the current disease paradigm, no major role for leukocytes in systemic Stx2 trafficking or kidney injury was observed in vivo, but a novel role for host immune responses to Stx2 in the control of intestinal colonization by Stx2-producing bacteria was identified. Cell stress and apoptosis is induced by Stx2 in vivo but prevention of these is not sufficient to appreciably alter organ injury or survival in the murine models

Examining demographic and psychosocial predictors of well-being in older pet owners

Background: Worldwide, older adults represent a significant proportion of the total population. Due to the international increase in the numbers of aging adults over the next several decades, it is important for nurses to assist this populace in aspects of healthy aging. There are known indicators of well-being both positive and negative that influence aging.Objective: The objective of this study was to examine seven models consisting of demographic and psychosocial predictors of well-being among older adults.Population: This quantitative descriptive design included 209 older pet-owning adults whose age ranged from 48 to 93 (M = 71.66; SD 9.14). The participants were recruited from senior housing facilities designed for older adults or attended a senior citizen community center.Methods: Participants completed a demographics form and a loneliness, pet attachment, social support, and well-being scale. Demographic and psychosocial predictors of well-being were examined using hierarchical regression analysis (p < .05).Results: The results revealed that age, gender, education, health, loneliness due to the loss, pet type, loneliness, social support, and pet attachment were significant predictors.Interpretation: Older adults are at risk for less than optimal well-being due to situational factors such as loneliness and alternations in social support due to natural life transitions. Since well-being is a multidimensional construct that affects the world’s people it is important for nurses to investigate its components.Conclusion: Internationally, nursing is focused on maintaining positive health and well-being throughout the lifespan. The findings supported both positive and negative components influence well-being. Appropriate interventions should be selected based on positive or negative predictors. Implications for clinical application are discussed

Rain-ash interaction during paroxysmal events as potential input of toxic trace element in the environment: example from Mt. Etna Volcano

Volcanic emissions represent one of the most relevant natural sources of trace elements to the troposphere, both during and between eruptions. Due to their potential toxicity they may have important environmental impacts from the local to the global scale. Mount Etna, the largest European volcano and one of the most active volcano in the world, covers an area of about 1250 km2 and reaches an altitude of about 3340 m. It has been persistently active during historical time, with frequent paroxysmal episodes separated by passive degassing periods. Atmospheric precipitation was collected approximately every two weeks, from April 2006 to December 2007, using a network of five rain gauges, located at various altitudes on the upper flanks around the summit craters of Etna Volcano. The collected samples were analysed for major (Ca, Mg, K, Na, F, SO4, Cl, NO3) and a large suite of trace elements (Ag, Al, As, Au, B, Ba, Be, Bi, Cd, Co, Cr, Cs, Cu, Fe, Hg, La, Li, Mn, Mo, Ni, Pb, Rb, Si, Sb, Sc, Se, Sr, Th, Ti, Tl, U, V, Zn) by using different techniques (IC, SPEC, ICP-MS and CV-AFS). The monitoring of atmospheric deposition gave the opportunity to occasionally sample volcanic fresh ashes emitted by the volcano during the paroxysmal events. This was possible because the network of five rain gauges were equipped with a filter-system to block the coarse material. In this way, more than twenty events of ashfall were collected. Unfortunately, only half of these samples were suitable for a complete chemical analysis, because of the small amount of sample. In order to obtain elemental chemical composition of ashes, powdered samples were analysed by a combination of methods, including X-ray Fluorescence Spectroscopy (XRF), total digestion followed by Inductively Coupled Plasma Emission Mass Spectrometry (ICP-MS), Instrumental Neutron Activation Analysis (INAA), and infrared detection (IR). The chemistry of rainwater reveals that most of the investigated elements have higher concentrations close to the emission vent of the volcano, confirming the prevailing volcanic contribution. Rainwater composition clearly reflects the volcanic plume input. Ash-normalised rainwater composition indicates a contrasting behaviour between volatile elements, which are highly-enriched in rainwater, and refractory elements, which have low rainwater/ash concentration ratios. The degree of interaction between collected ash and rainwater was variable, depending on several factors: (i) the length of the period in which tephra was present in the sampler (the ash fall may have occurred any day from the first to the last day of the rain collecting period); (ii) the amount of rainwater fallen on the collectors after the ash-fall event, and its acidity; (iii) the granulometry of the ash samples that was widely variable (from few centimetres to micrometric particles) increasing the interaction with decreasing dimensions of the grains; (iv) the distance of collector with respect to the craters. In order to investigate the role of volcanic ash on the evolution of the rainwater chemistry, absolute concentrations of rain and ash were plotted in binary plot diagrams (Figure 1). Each diagram corresponds to a single event, and pH and TDS of the solution collected is reported. The diagonal bars in the diagrams represent the rain/ash ratios (1:1 and 1:10000). The results confirm that sulphate and halide salt aerosols are adsorbed onto ash particles, and their rate of dissolution in rainwater depends on solubility. Moreover, rapid chemical weathering of the silicate glass by volcanic acid (SO2, HCl and HF) can also explain the enrichment of several refractory elements (Na, K, Ca, Mg, Si, Al, Fe, Ti, Sc). Our observations highlight how explosive activity can increase enormously the deposition rate of several chemical elements, up to several km away from the emission vents