Explaining the Diversification Path of Exporters in Brazil: How Similar and Sophisticated are New Products?

A stylised fact of the economic literature suggests that export diversification is good for economic growth and is associated with economic development. In addition, there is evidence suggesting that the level of sophistication of countries’ exports “matters” for growth and development. This paper contributes to this literature by analysing two unexplored dimensions of export diversification: the degree of relatedness (similarity) and sophistication of new products in relation to existing ones. The objective of this paper is to understand the mechanisms through which firms are able to diversify to less related and more sophisticated activities. We do so using a unique dataset that links data on exports, innovation and firms’ characteristics at the firm level in Brazil. The main findings suggest that i) diversification occurs in very closely related activities, where firms have some core competences, ii) most diversification occurs in new products with lower level of sophistication than existing exports, iii) the degree of diversification and innovativeness of the production basket, and the position that the firm has developed in the domestic market appear to matter for diversification towards more or less distant products.Diversification; Relatedness; Sophistication; Trade; Innovation; Brazil

Endodermal growth factors promote endocardial precursor cell formation from precardiac mesoderm

AbstractWe previously demonstrated that the initial emergence of endocardial precursor cells (endocardial angioblasts) occurred within the precardiac mesoderm and that the endodermal secretory products promoted delamination of cells from the precardiac mesoderm and expression of endothelial lineage markers [Dev. Biol. 175 (1996), 66]. In this study, we sought to extend our original study to the identification of candidate molecules derived from the endoderm that might have induced endocardial precursor cell formation. We have detected expression of transforming growth factors β (TGFβ) 2, 3, and 4 in anterior endoderm at Hamburger and Hamilton (H-H) stage 5 by RT-PCR. To address the role of growth factors known to be present in the endoderm, precardiac mesodermal explants were isolated from H-H stage 5 quail embryos and cultured on the surface of collagen gels with serum-free defined medium 199. Similar to the effect of explants cocultured with anterior endoderm, when cultured with TGFβs 1–3 (3 ng/ml each), explants formed QH-1 (anti-quail endothelial marker)-positive mesenchymal cells, which invaded the gel and expressed the extracellular marker, cytotactin (tenascin). Another member of the TGFβ superfamily, bone morphogenetic protein-2 (BMP-2; 100 ng/ml), did not induce QH-1-positive mesenchymal cell formation but promoted formation of an epithelial monolayer on the surface of the collagen gel; this monolayer did not express QH-1. Explants treated with vascular endothelial growth factor (VEGF165, 100 ng/ml) also did not invade the gel but formed an epithelial-like outgrowth on the surface of the gel. However, this monolayer did express the QH-1 marker. Fibroblast growth factor-2 (FGF-2; 250 ng/ml)-treated explants expressed QH-1 and exhibited separation of the cells on the surface of the gel. Finally, a combination of TGFβs and VEGF enhanced formation of QH-1-positive cord-like structures within the gel from mesenchyme that had previously invaded the gel. Luminization of the cords, however, was not clearly evident. These findings suggest that TGFβs, among the growth factors tested, mediate the initial step of endocardial formation, i.e., delamination of endothelial precursor cells from precardiac mesoderm, whereas VEGF may primarily effect early vasculogenesis (cord-like structure formation)

Formation and Early Morphogenesis of Endocardial Endothelial Precursor Cells and the Role of Endoderm

AbstractThe formation of endocardial endothelium in quail embryos was investigated usingin vivoandin vitrosystems. Based on the expression of an quail endothelial marker, QH-1, the initial emergence of endothelial precursor cells in the embryo occurs at stage 7+(two somites) in the posterior parts of the bilateral heart forming regions. Cells that expressed the QH-1 antigen were mesenchymal and positioned between the mesodermal epithelium of the heart region and the endoderm. By confocal microscopy, an asymmetrical distribution of QH-1 positive cells was observed between the two heart regions: specifically between 7+and 8−, more precursor cells were seen in the right region than the left. Endothelial precursor cells did not appear outside of the heart forming regions until stage 8−(three somites). Free, mesenchymal-like endothelial precursor cells intrinsic to the heart regions also expressed two extracellular antigens, JB3, a fibrillin-like protein, and cytotactin, both associated with segments of the primary heart tube where endothelial cells “re-transform” back to a mesenchymal phenotype during cardiac cushion tissue formation. Between stages 8 and 9 (four to seven somites), (1) QH-1 positive cells within the heart forming region established vascular-like connections with QH-1 positive cells located outside of the heart region, as initially shown by Coffin and Poole (1988), (2) after fusion of the heart regions, a plexus of QH-1 positive cells was formed ventral to the foregut, and (3) the definitive endocardial lining of the primary heart tube formed directly from the ventral plexus of endothelial precursor cells. Because the QH-1 positive, endothelial precursor cells of each heart forming region were always in close association with anterior endoderm, we sought to determine if the endoderm mediated the formation of precursor cells committed to a cardiac endothelial lineage as reflected by their expression of QH-1, JB3 antigen, and cytotactin. To test this hypothesis, precardiac mesodermal explants were isolated from stage 5 heart forming regions prior to their expressing of either endocardial or myocardial markers and cultured on the surface of collagen gels in the presence or absence of endoderm. In the absence of endoderm, precardiac mesoderm of each stage 5 explant remained epithelial, formed contractile tissue, but did not exhibit any QH-1 positive cells or mesenchymal cells. Conversely, when cocultured with endoderm or endoderm conditioned medium, in addition to the formation of contractile tissue, the explant formed mesenchymal cells. The latter invaded the gel lattice and, asin vivo,expressed QH-1 antigen, JB3 antigen, and cytotactin. These findings suggest that endoderm induces mesoderm of the heart fields to undergo an epithelial to mesenchyme transformation that results in the segregation of myocardial and endocardial precursor cells

Firm behaviour and the introduction of new exports : evidence from Brazil

This paper contributes to understanding the process of export diversification by analysing firm level determinants in Brazil during the period 2000–2009. The first objective of the paper is to establish the set of firm characteristics and processes that are more conductive to new exports; the second, to identify different pathways to diversification regarding relatedness and sophistication and, which firm level behaviours can be associated to the different paths. We answer these questions using a unique dataset that links data on exports, innovation and firms characteristics at the firm level. The paper contributes to the literature on export diversification and on preparation for exporting by identifying firm level behaviours that contribute to the process of diversification. In particular, the findings suggest that firms prepare for diversification by first gaining power in the domestic market and more importantly that they do so by adopting specific innovation and learning efforts. Keywords: diversification; relatedness; sophistication; trade; innovation; Brazil JEL: F14; L2

The Impact of Melatonin, Melatonin Analogues, Caffeine, and Bright Light on Sleep and Thermoregulatory Physiology

doses under controlled conditions during the daytime, when endogenous levels are low. Study findings have demonstrated that exogenous melatonin improves sleep, increases peripheral heat loss, and decreases core body temperature (CBT). These thermoregulatory adjustments mimic those that occur around habitual bedtime, when endogenous melatonin levels are high. The emergences of artificial light and stimulants i.e., caffeine have impacted the behavior and physiology that normally precede sleep. Caffeine may independently impact sleep/wakefulness, or in conjunction with the thermoregulatory system. Bright light during the biological night suppresses melatonin and changes the thermoregulatory pattern that precedes nocturnal sleep; these changes may ultimately impact the sleep/wakefulness system. To improve our understanding of physiological mechanisms promoting and disrupting sleep/wakefulness, it is important to examine the connection between melatonin and the sleep/wakefulness and thermoregulatory systems, and the impact of environmental and behavioral factors on these systems. Therefore, the aims of this dissertation were to: 1) determine the effect of a melatonin receptor analogue ramelteon, on daytime sleep and body temperature, and the relationship between the two variables; 2) determine the effect of daytime exogenous melatonin on resting energy expenditure, (REE); and 3) determine the individual and compound effects of caffeine and bright light on thermoregulatory and sleep physiology at night. Consistent with our hypotheses, 1) ramelteon significantly improved daytime sleep, lowered CBT, and increased peripheral heat loss 2) exogenous melatonin decreased REE during the daytime, and 3) caffeine delayed the nocturnal rise in peripheral heat loss, attenuated the fall in CBT, while the combination of caffeine and bright light decreased slow wave sleep and increased sleep onset latency. These findings suggest that melatonin may play an important role in the regulation of sleep/wakefulness as evidenced by the effect of daytime ramelteon administration on sleep and thermoregulatory physiology and the effect of daytime exogenous melatonin on REE. Finally, caffeine and bright light had a negative impact on nocturnal sleep and these effects may be mediated in part by their impact on the thermoregulatory system

Welcome to The new anatomist

No abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34282/1/1_ftp.pd

Bioprinting: Development of a novel approach for engineering three-dimensional tissue structures [abstract]

Abstract only availableBioprinting is a tissue engineering technique in which spherical cell aggregates, the "bio-ink", are deposited into biocompatible hydrogels, the "bio-paper", by a 3-axis "bio-printer". The aggregates can be deposited into essentially any 3D configuration, and when comprised of adhesive and motile cells aggregate fusion occurs. This self-organizing, liquid-like nature of these tissues is described on a molecular basis by The Differential Adhesion Hypothesis (DAH). The techniques we have developed are quite unique because of the high degree of automation that has been incorporated into our processes and the variety of engineered tissues that we are capable of creating. Despite automation, the creation of aggregates remains a nontrivial and time intensive process. The entire process of aggregate formation from initial cell culture to mature aggregate ready to be loaded into the printer takes approximately five days. This time is a limiting factor in the potential use of bio-printing as a source of on-demand tissues for clinical applications. A solution to this potential problem lies in the cryopreservation of aggregates. Freezing mediums and freezing protocols were tested and the effect of the freezing process on aggregate fusion was determined. An alternate solution to expedite the bioprinting process could lie in the printing of cell 'sausages', tightly packed cylinders of cells. In this method aggregate preparation is forgone. Elimination of this step could allow for increased time in tissue creation. Cell sausage printing provides another technique that could be incorporated into the fabrication of complex tissues. Our experiments in this novel and developing technology of bioprinting represent steps towards building complex tissues via self-assembly.McNair Scholars Progra

The role of Periostin in regulating the biomechanical properties of cushion tissue

Abstract only availableDuring embryonic heart development the atrio-ventricular (AV) cushions swell and fuse to form the valves and septa of the adult heart. Initially, the cushions appear as swellings on the interior wall of the AV canal and eventually fuse to form the septum and valvular leaflets. The morphogenetic event that the cushions undergo during the fusion process is, in part, driven by the cohesive energy of the tissue, which can be described by the tissue's surface tension. It has been shown earlier that many properties of embryonic tissues can be interpreted by using the analogy that they behave as liquids and it is this analogy that gives rise to apparent tissue surface tension. Periostin is hypothesized to affect cushion tissue surface tension, through its possible binding of the extracellular matrix of the tissue. In this study virus containing the sense strand of Periostin DNA is introduced into hanging drops containing living explants of AV cushion tissue. Overnight the tissue explants rounded up to form spheroids allowing their surface tension to be measured and compared to the surface tension of AV cushion tissue explants exposed to a LacZ promoter control virus. The surface tension was determined using a specifically designed apparatus that measures the viscoelastic response of spherical explants due to a compressive force. It was expected that the increased production of Periostin in the cushion explants due to exposure to the virus will result in an increased surface tension compared to that of explants exposed to the control virus. The preliminary results of the experiment have displayed no significant difference of surface tension between the control virus and the Periostin virus. Since earlier research has shown a significant difference in the rate of fusion of cushions exposed to Periostin DNA virus and those exposed to the control virus, and because fusion time is characterized by the ratio of the surface tension and the viscosity of the tissue, we believe that Periostin may be affecting the viscosity of the tissue explants instead of the surface tension.NSF-REU Program in Biosystems Modeling and Analysi

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