Migration and economic development: a review of theory, evidence, methodology and research priorities

In this paper the author surveys the most recent literature on internal migration in developing nations. He also treats briefly the history of migration in the economically advanced countries and more recent international migration. After discussing the significance of the problems associated with migration and reviewing the noneconomic literature on the subject, he concentrates on recent economic theories of rural-urban migration and examines the rapidly growing number of quantitative and econometric migration studies. The paper concludes with suggestions for future research priorities in light of what we now seem to know about migration and development

Urbanization, unemployment and migration in Africa: Theory and policy [Arabic]

During the past three decades, the cities of the developing world in general, and of Africa in particular, have witnessed a remarkable and in many ways unprecedented demographic growth spurt. Despite some slowdown in rates of increase in the past few years as a result of falling wages, contracting social services, and changing demographic trends, contemporary urban areas remain the growth poles of economic progress and the lightning rods of political and social unrest. Nowhere is this dilemma more visible nor the resulting problems more intractable than in the crowded cities of sub-Saharan Africa, where projections of urban population growth remain the highest in the world. This essay focuses on the conceptual, empirical, and policy-relevant linkages among urbanization, rural-urban migration, and economic development. First, recent trends and future scenarios for urban population growth are reviewed, with special emphasis on African urbanization. Then, the growth and significance of the urban informal economy and the role of women in informal economic activities are examined. Rural-urban migration is discussed in both a descriptive and an analytical framework; the economic crisis in Africa and its relationship to urbanization and migration are considered. An analysis of policy options designed to ameliorate the deteriorating economic, social, and environmental dilemmas posed by Africa’s rapid urban growth concludes the study

Urbanization, unemployment and migration in Africa: Theory and policy

During the past three decades, the cities of the developing world in general, and of Africa in particular, have witnessed a remarkable and in many ways unprecedented demographic growth spurt. Despite some slowdown in rates of increase in the past few years as a result of falling wages, contracting social services, and changing demographic trends, contemporary urban areas remain the growth poles of economic progress and the lightning rods of political and social unrest. Nowhere is this dilemma more visible nor the resulting problems more intractable than in the crowded cities of sub-Saharan Africa, where projections of urban population growth remain the highest in the world. This essay focuses on the conceptual, empirical, and policy-relevant linkages among urbanization, rural-urban migration, and economic development. First, recent trends and future scenarios for urban population growth are reviewed, with special emphasis on African urbanization. Then, the growth and significance of the urban informal economy and the role of women in informal economic activities are examined. Rural-urban migration is discussed in both a descriptive and an analytical framework; the economic crisis in Africa and its relationship to urbanization and migration are considered. An analysis of policy options designed to ameliorate the deteriorating economic, social, and environmental dilemmas posed by Africa’s rapid urban growth concludes the study

Baseline Q-Wave Surpasses Time From Symptom Onset as a Prognostic Marker in ST-Segment Elevation Myocardial Infarction Patients Treated With Primary Percutaneous Coronary Intervention

ObjectivesWe assessed the incremental value of baseline Q waves over time from symptom onset as a marker of clinical outcome in ST-segment elevation myocardial infarction (STEMI).BackgroundTime from symptom onset is a central focus in STEMI patients. The presence of Q waves on the baseline electrocardiogram (ECG) has been suggested to be of incremental value to time from symptom onset in evaluating clinical outcomes.MethodsWe evaluated baseline Q waves and ST-segment resolution 30 min after primary percutaneous intervention (PCI) ECGs in 4,530 STEMI patients without prior infarction. Additionally, peak biomarkers; 90-day mortality; and the composite of death, congestive heart failure (CHF), or cardiogenic shock were assessed.ResultsFifty-six percent of patients had baseline Q waves: they were older, more frequently male and diabetic, and had a more advanced Killip class. Patients with baseline Q waves had greater mortality and a higher composite rate of death, CHF, and shock versus patients without baseline Q waves at 90 days (5.3% vs. 2.1% and 12.1% vs. 4.8%, respectively, both p < 0.001). Complete ST-segment resolution was highest, whereas 90-day mortality and the composite outcome were lowest among those randomized ≤3 h without baseline Q waves. After multivariable adjustment, baseline Q-wave but not time from symptom onset was significantly associated with a 78% relative increase in the hazard of 90-day mortality and a 90% relative increase in the hazard of death, shock, and CHF.ConclusionsBaseline Q waves in STEMI patients treated with primary PCI provide an independent prognostic marker of clinical outcome. These data might be useful in designing future clinical trials as well as in evaluating patients for triage and potential transfer for planned primary PCI. (Pexelizumab in Conjunction With Angioplasty in Acute Myocardial Infarction [APEX-AMI]; NCT00091637

ALDH Activity Selectively Defines an Enhanced Tumor-Initiating Cell Population Relative to CD133 Expression in Human Pancreatic Adenocarcinoma

Multiple studies in recent years have identified highly tumorigenic populations of cells that drive tumor formation. These cancer stem cells (CSCs), or tumor-initiating cells (TICs), exhibit properties of normal stem cells and are associated with resistance to current therapies. As pancreatic adenocarcinoma is among the most resistant human cancers to chemo-radiation therapy, we sought to evaluate the presence of cell populations with tumor-initiating capacities in human pancreatic tumors. Understanding which pancreatic cancer cell populations possess tumor-initiating capabilities is critical to characterizing and understanding the biology of pancreatic CSCs towards therapeutic ends. cell populations were further examined for co-expression of CD44 and/or CD24. We demonstrate that unlike cell populations demonstrating low ALDH activity, as few as 100 cells enriched for high ALDH activity were capable of tumor formation, irrespective of CD133 expression. In direct xenograft tumors, the proportions of total tumor cells expressing ALDH and/or CD133 in xenograft tumors were unchanged through a minimum of two passages. We further demonstrate that ALDH expression among patients with pancreatic adenocarcinoma is heterogeneous, but the expression is constant in serial generations of individual direct xenograft tumors established from bulk human pancreatic tumors in NOD/SCID mice. phenotypes do not appear to significantly contribute to tumor formation at low numbers of inoculated tumor cells. ALDH expression broadly varies among patients with pancreatic adenocarcinoma and the apparent expression is recapitulated in serial generations of direct xenograft tumors in NOD/SCID. We have thus identified a distinct population of TICs that should lead to identification of novel targets for pancreatic cancer therapy