1,470 research outputs found

    Real inequality in Europe since 1500

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    Introducing a concept of real, as opposed to nominal, inequality of income or wealth suggests some historical reinterpretations, buttressed by a closer look at consumption by the rich. The purchasing powers of different income classes depend on how relative prices move. Relative prices affected real inequality more strongly in earlier centuries than in the twentieth. Between 1500 and about 1800, staple food and fuels became dearer, while luxury goods, especially servants, became cheaper, greatly widening the inequality of lifestyles. Peace, industrialization, and globalization reversed this inegalitarian price effect in the nineteenth century, at least for England

    Trade costs, 1870–2000

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    What has driven trade booms and trade busts in the past century and a half? Was it changes in global output or in the costs of international trade? To address this question, we derive a micro-founded measure of aggregate bilateral trade costs based on a standard model of trade in differentiated goods. These trade costs gauge the difference between observed bilateral trade and frictionless trade in terms of an implied markup on retail prices of foreign goods. Thus, we are able to estimate the combined magnitude of tariffs, transportation costs, and all other macroeconomic frictions that impede international trade but that are inherently difficult to observe. We use this measure to examine the growth of global trade between 1870 and 1913, its retreat from 1921 to 1939, and its subsequent rise from 1950 to 2000. We find that trade cost declines explain roughly 55 percent of the pre–World War I trade boom and 33 percent of the post–World War II trade boom, while a precipitous rise in trade costs explains the entire interwar trade bust

    Ozone Induces Nerve Growth Factor Release from Rat Tracheal Epithelial Cells during an Early Postnatal Critical Period

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    Ozone, one of the major air pollutants in urban areas, produces epithelial cell injury and inflammation in the airways upon exposure. Previous studies have shown that ozone exposure leads to increased substance P (SP) expression in nerves innervating the smooth muscle in the extrapulmonary airway. Nerve growth factor (NGF), a neurotrophin, is known to increase SP expression. To determine the effect of ozone exposure on the release of NGF, a cell culture technique was developed for studying a homogenous rat tracheal epithelial cell population for analysis of NGF mRNA and protein expression. Furthermore, to determine if this effect is age-dependent, a critical period exposure paradigm was used. Rat pups exposed to ozone at postnatal day (PD) 6 showed an increase in the level of NGF mRNA while pups exposed after PD 6 showed no change in NGF expression. When rat pups exposed to ozone on PD 6 were reexposed at a later date, an increase in NGF mRNA was observed. These data suggest that exposure to ozone has an effect on NGF expression in early postnatal life and that this exposure might play a role in ozone sensitivity later in life

    Computer-Mediated Friendship Networks

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    Social networks have been around since the dawn of civilization. What is unique about social networks today is that a large part of these social networks is computer-mediated. Computer-mediated friendship networks (CMFNs) are a prime example of IT that matters. This research-in-progress focuses on the antecedents to CMFN usage based on Self-Determination Theory and Socio-Emotional Selectivity Theory. Findings show that Perceived Intrinsic Value, Perceptions of Homophily, and Perceptions of Emotional Support as well as Stage of Life impact CMFN usage in interesting ways. Contributions of this study include 1) showcasing the important role that friendship style plays in CMFNs, 2) empirically demonstrating the role of intrinsic motivation in an information system which has been unsuccessful previously, and 3) extending the literature on computer-mediated social networking by defining and analyzing a particular category of computer-mediated social networks, namely, the CMFN, which has not been examined previously in the literature

    Metal contamination at a wood preservation site : characterisation and experimental studies on remediation

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    http://www.elsevier.com/locate/issn/00489697The aim of this investigation was to determine the occurrence of As, Cu, Cr and Zn in the soil at an abandoned wood preservation unit and to examine some possible extractants for the contaminants in the soil.The mean As content of the contaminated surface soils (0–10 cm) was 186 mg kgy1, where as the mean concentrations of Cu, Cr and Zn in soils from the contaminated area were 26, 29 and 91 mg kgy1, respectively.The elevated As content in the mineral soils is related to adsorption of inorganic As phases in the fine grained fractions, which are characterised by large surface area and high positive surface charge under the current acidic conditions.Cu and Cr were found to be rather mobile, which is reflected in their lower abundance in soils and significant accumulation in sediments in the drainage leaving the area.The fine fraction of the soil (-0.125 mm) has an average metal content increased by nearly 34% as compared to the -2-mm fraction conventionally used for the analysis and assessment of soil contamination.The -2-mm fraction constitutes approximately 65% of the total weight while the fine fraction (- 0.125 mm) constitutes approximately 10%.These facts, taken together, are essential for the choice of remediation measures.Oxalate solutions have been tested as extractants for soil remediation. Dark acid oxalate extraction dissolves the amorphous Al- and Fe-oxides and hydroxides and mobilises the adsorbed inorganic As species.Oxalate also acts as a ligand for the cationic heavy metals, releasing them from exchangeable sites.With a three-step sequential leaching, up to 98–99% of the metals could be removed.At lower concentrations and higher pH, the leaching decreased to approximately 70%

    Effects of ethanolic extract of datura stramonium leaves on the histomorphology and biochemical indices of liver and kidney functions in rats

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    Changes in histomorphology and some indices of liver and kidney functions were studied in rats administered doses of ethanolic extracts of Datura stramonium leaves. Methods: Four experimental groups of rats were respectively given oral doses of 50mg/kg, 100mg/kg and 200mg/kg of the extract daily for six weeks. Rats were sacrificed at the end of the six weeks and blood samples were collected for biochemical analysis. The livers and kidneys of the rates were harvested for histological studies. Results: The results showed that alanine transaminase (ALT) and bilirubin levels were significantly (P<0.05) higher in the groups administered 100mg/kg and 200mg/kg extracts than the control group. The extracts at similar doses also increased significantly (p<0.05) the serum urea and creatinine levels. Histological evaluation of the organs of localization revealed dose-dependent effects of treatment with the extract. Conclusion:The study has shown that Datura stramonium leaf extracts administered with 100 200mg/kg for six weeks caused liver and kidney damages in rats

    ARF Is Not Required for Apoptosis in Rb Mutant Mouse Embryos

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    AbstractThe retinoblastoma (RB) tumor suppressor gene occupies central roles in cell cycle control and tumor suppression [1]. Homozygous mutant (Rb−/−) embryos die at E13.5–E15.5 [2–4], exhibiting extensive apoptosis and inappropriate S phase entry in the central and peripheral nervous systems, liver, and ocular lens [2–6]. Mice simultaneously mutant for Rb and other genes can be generated to assess the requirement for these genes in cell cycle control and apoptosis. Using such analysis, E2f-1, E2f-3, p53, and Id2 have been identified as important regulators of cell cycle control and apoptosis in Rb−/− embryos [7–10]. Because unrestrained E2F activity in the absence of Rb function contributes to p53-dependent apoptosis in many systems [7, 9, 11–14], we wished to identify genes linking deregulated E2F activity to p53 activation and subsequent apoptosis. As a transcriptional target of E2F-1 [15–18], a regulator of p53 [19–21], and an important mediator of apoptosis [20–26], ARF was a strong candidate for such a role, especially since it can be upregulated in the absence of Rb[21]. From the analysis of Rb/ARF compound mutants we demonstrate that ARF is not an obligatory link between Rb inactivation and p53-dependent apoptosis

    Dicer loss and recovery induce an oncogenic switch driven by transcriptional activation of the oncofetal Imp1–3 family

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    MicroRNAs(miRNAs) are post-transcriptional regulators of gene expressioncritical for organismal viability. Changes inmiRNAactivity arecommonin cancer, buthowthese changes relate to subsequent alterations in transcription and the process of tumorigenesis is not well understood. Here, we report a deep transcriptional, oncogenic network regulated bymiRNAs. Wepresent analysis of the gene expression and phenotypic changes associated with globalmiRNA restoration in miRNA-deficient fibroblasts. This analysis uncovers a miRNA-repressed network containing oncofetal genesImp1, Imp2, and Imp3(Imp1–3) that is up-regulated primarily transcriptionally > 100-fold uponDicer loss and is resistant to resilencing by complete restoration of miRNA activity. This Dicer-resistant epigenetic switch confers tumorigenicity to these cells. Let-7 targets Imp1–3 are required for this tumorigenicity and feed back to reinforce and sustain expression of the oncogenic network. Together, these Dicer-resistant genes constitute an mRNA expression signature that is present in numerous human cancers and is associated with poor survival.United States. Public Health Service (Grant R01CA133404)National Cancer Institute (U.S.) (Grant P01CA42063)Marie D. and Pierre Casimir-Lamber
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