Brain Circulation

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Brain Circulation: Theoretical Considerations

Brain Circulation: Theoretical Considerations

Firstly, there should be a decentralized industrial system with strong division of labour and innovation among networked firms. Secondly, the agglomerated economies between the two places, organizations must encourage entrepreneurship and learning between the firms on the regional level. Equally, high-tech firms must try to avoid being locked into the social relations while continuing the collaborative division of labor and inter- firm learning in the high-tech sector (e.g. Hsinchu – Silicon Valley). Thirdly, venture capital is essential to technologically risky startups with super–profit compensation when it does Initial Public Offering (IPO) or is acquired by other companies. Fourthly, the role of the state in facilitating technology transfer must be significant. Governments should fund private sectors, because they put more emphasis on their activities in innovation, thus stimulating countries economic development, its competitiveness. Summarizing the analysis of this figure, it is necessary to highlight that the combination of these four structural elements could be a key of success while stimulating brain circulation phenomenon.
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From brain drain to brain circulation : attracting high skilled migrants back

From brain drain to brain circulation : attracting high skilled migrants back

discussion on the agenda (Meyer, 2001). Beine, Docquier and Rapoport (2008) agree with Meyer (2001) that the emphasis is now on science, technology and educational policies. They add the fact that since the return to education is higher abroad, skilled migrants can raise the return to human capital and encourage more people to invest in education at home (Beine, Docquier & Rapoport, 2008). While many countries seem to benefit from the brain circulation, there are still situations where the problem of brain drain occurs. Take for example the many small countries in Sub-Saharan Africa and Central America, in particular. The situation here is extremely worrisome. While the main globalizers (China, India, Brazil) all seem to experience non-negligible gains, these countries still face brain drain problems (Beine, Docquier & Rapoport, 2008). Marchal and Kegels (2003) underline this fact and state that the cause for the problem in these countries is the migration of health personnel. Health personnel, and in particular nurses and doctors, but recently also physiotherapists, pharmacists and biomedical researchers, probably even account for the majority of skilled migration (Martineau et al., 2002 in Marchal & Kegels, 2003). According to Docquier, Lohest & Marfouk (2007), the countries in Sub-Saharan African face various disadvantages such as a low level of development, high political instability, and religious and ethnic fractionalization. The brain drain has therefore different possible causes, many of which cannot be affected by public interventions. To focus on areas that can be influenced by public policy, for example promoting education and improving the political climate at origin, could help to reduce the brain drain or turn it into brain circulation (Docquier, Lohest & Marfouk, 2007). The brain drain can also lead to brain waste when skilled personnel who migrated to developed countries are employed in functions below their level of qualification (Bundred & Levitt, 2000 in Marchal & Kegels, 2003). This situation is a loss for both countries. However, the gains from brain circulation outweigh the losses from the losers, which results in an overall gain for developing countries as a whole (Beine, Docquier & Rapoport, 2008).
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Brain Circulation at Industry-Level: Evidence from the Knowledge Services Industry in Sri Lanka

Brain Circulation at Industry-Level: Evidence from the Knowledge Services Industry in Sri Lanka

In addition, it is generally accepted that the rapidly growing industries in the home country are necessary to encourage the reverse flow of skilled migration as growing industries generate professional opportunities and premium wage for the educated. However, business start-ups and subsequent rapid growth of Taiwan’s ICT industry were significantly influenced by the returned entrepreneurs-The New Argonauts- who had the cultural identities as Taiwanese and close links with the technological centers such as Silicon Valley (Saxenian, 2006, 124). In terms of the quality of returning skilled migrants, Stark et al. (1997) argued that low-ability immigrant employees receive a lower- wage in the developed country. Therefore, these low-ability skilled migrants will return at the early stage of industry growth. The literature does not distinguish the different characteristics of returned entrepreneurs and returned employees. A notable exemption is Iredala et al. (2003) that distinguished the determinants of the returned skilled migrants and returned business migrants in four Asia Pacific countries. Yet, the findings have been over generalized using a diverse, but small samples, which include returned migrants from all the three economic sectors; agriculture, industry and services, and from both public and private sectors. Finally, in contrast to the country-specific nature of brain drain, brain circulation has emerged as an industry-specific process. The same country might experience a multidirectional flow of human capital depending on the competitiveness of the industries. For instance, Canada is experiencing a beneficial brain circulation within the IT industry while losing its best brain in other disciplines to the USA (Schmitt & Soubeyran, 2006). Therefore, industry-specific determinants of brain circulation are useful than the macro-level and micro-level determinants to validate the brain circulation thesis.
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Post Graduation Strategies for Students from Developing Countries: An Exploration of four Developed Countries through the Lenses of Brain Drain, Brain Gain and Brain Circulation

Post Graduation Strategies for Students from Developing Countries: An Exploration of four Developed Countries through the Lenses of Brain Drain, Brain Gain and Brain Circulation

The brain circulation approach is particularly applicable for the movement of highly skilled manpower between developing and developed countries. It suggests that highly skilled workers once sent out, set up links with their home countries, resulting in an interconnectedness with other countries in forms of well connected diasporas (Nuffic, 2004). It is assumed that the mobility of people has a positive impact on the development of competencies within that environment and on the people themselves (Carr, et al., 2005b). The closer investigation of Silicon Valley by Saxenian (2005) proofs that those people who left the country in the first place are either returning after a certain time or create networks and ties with their home country. Saxenian states that what previously have been remittances are nowadays transnational communities who “foster economic development directly, by creating new jobs and wealth, as well as indirectly, by coordinating the information flows and providing the linguistic and cultural know-how that promote trade and investment in their home countries” (Saxenian, 2002). Accordingly a strong connection is seen between sending and receiving country, not identifying winners and losers and instead focusing on a mutual benefit situation. Furthermore it is ascertained that people actually circulate between countries (i.e.: from the USA to developing countries) (Saxenian, 2006b).
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Brain Circulation in Mexico: The Debate Remains

Brain Circulation in Mexico: The Debate Remains

These success stories promote to analyses of the diaspora networks and their results. Kuznetsov & Sabel [27] focused their study on diaspora networks results, through a comparative analysis in China and Chile. They found that Chinese diaspora had been more involved in the developed strategy of their own country than the Chileans abroad. Chinese diaspora had contributed large sums of foreign investment in order to support entrepreneurship. By contrast, brain circulation in Chile just begins to bear fruit. Through highly skilled expatriate networks Chile was able to create successful compa- nies such as Biogenética with the purpose of undertaking researches and to promote technology transfer projects in the agribusiness sector in Chile. A Chilean specialist in genetics and biotechnology established in the US, and Chile Foundation founded this company; the authors refer that the success of this company would not have been poss- ible without the knowledge, experience and participation the expatriate scientist. Ac- cording to the authors, Biogenética has achieved to improve the production of grapes and stone fruits, two export crops that are important for the Chilean economy.
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Donation after brain circulation determination of death

Donation after brain circulation determination of death

1) The possibility of auto-resuscitation has elapsed Auto-resuscitation refers to the spontaneous return of heartbeat and circulation after asystole [2]. To avoid the possibility of a patient ’ s revival after having been declared dead, death cannot be declared until the possibility of auto-resuscitation has elapsed. The minimal no-touch period to wait to ensure the impossibility of auto-resuscitation is unknown [40]. In one comprehensive retrospective study of withdrawal of life-sustaining therapy, the investigators found not a single case of auto- resuscitation to restored circulation [41]. An observational study showed that ‘ the longest period of cessation of arterial blood pressure before resumption was 89 sec [40]. While cardiac electrical activity persisted in some patients for more than 30 min after cardiac arrest, the authors concurred that ‘true autoresuscitation required the spontaneous return of circulation ’ and not merely the return of cardiac electrical activity [2, 39–41]. By contrast, after failed CPR in the setting of unexpected cardiac arrest, auto-resuscitation to circulation remains possible after 7 min of cardiac arrest [41]. Available data suggest that in controlled DCDD following withdrawal of life-sustaining therapy, a no-touch period of 5 min is sufficient to ensure the impossibility of auto-resuscitation. But in uncon- trolled DCDD after failed resuscitative efforts in an unexpected cardiac arrest, a no-touch period for as long as 10 min may be necessary [42].
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Rapamycin Increases Collateral Circulation in Rodent Brain after Focal Ischemia as detected by Multiple Modality Dynamic Imaging

Rapamycin Increases Collateral Circulation in Rodent Brain after Focal Ischemia as detected by Multiple Modality Dynamic Imaging

The brain circulation system begins at the internal carotid artery (ICA) and extends through the anterior cerebral artery (ACA), middle cerebral artery (MCA), and posterior cerebral artery (PCA) to supply blood flow to the entire brain. In general, each artery supports only its own territory. Previous studies have suggested that collaterals do exist between the ICA and the external carotid artery (ECA), the ACA and MCA, and the PCA and MCA [12-14]. However, flow across these collaterals is very low due to little or no pressure drop, and they receive perfusion only following focal ischemia [15]. When and how collateral formation occurs during cerebral ischemia is not completely understood. Because the diameter of collateral arteries often ranges between 30 and 300 µm and collateral arteries are located at the skull base, the leptomeningeal/pial membrane, and the deep brain region, current small-animal imaging techniques are insufficient to assess collateral blood flow [16]. Many study data involving living animals have been acquired from the limited surface of the brain rather than from the entire brain, including the skull base and deep and surface regions of the brain [17-21]. Therefore, developing a feasible approach to directly and dynamically study collaterals using a multiscale approach could greatly improve our understanding of collateral perfusion and formation.
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Protecting Circulation with Enzyme Nutrition

Protecting Circulation with Enzyme Nutrition

Stressful era of modernization has led to high rates of cardiovascular diseases; thence it would then seem prudent to add this effective natural product to our heart health preventive arsenal as more recently, both clinical and non- clinical studies have demonstrated that Nattokinase suppor ts hear t health and promotes healthy circulation. More recent uses include meal replacements, medical foods, tablets, capsules, cold extruded bars, dry mixes and yoghurt drinks and cheese manufacture.

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The Nordic Seas circulation and exchanges

The Nordic Seas circulation and exchanges

Chapter 1: Introduction 3 sealers and whalers, and earlier (e.g. Koch, 1945), and there have been oceanographic studies since the era of Knudsen (1899) and Nansen (1902). However, while many of the key processes involved in the ventilation, pathways and overflows of the Nordic Seas are quantified and understood, there remain many outstanding questions, and an overall understanding of the components of the Nordic Seas system is yet to be established. To this end, this thesis quantifies the full Nordic Sea flux field (volume, heat and freshwater), thus determining the exchanges between the Nordic Seas and the Arctic Ocean to the north, the Barents Sea to the east, and North Atlantic to the south, via the North Atlantic Current inflow and the Denmark Strait and Iceland-Scotland overflows. This is the first study to be able to make use of synoptic hydrographic data across the entire region with concurrent direct velocity measurements on most sections; and can therefore provide a new estimate of the long-term mean summer fluxes and exchanges. The winter data also allow a winter circulation to be constructed, suggesting how the summer mean field might be extrapolated to provide an estimate of the ‘true’ annual mean flux field.
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Dynamics of Earth's Hadley Circulation

Dynamics of Earth's Hadley Circulation

ter), and v the meridional velocity; overbars indicate a temporal and zonal mean. The local Rossby number Ro = − ζ/f ¯ , with relative vorticity ζ, is a nondimensional measure of the importance of nonlinear angular momentum advection by the mean meridional circulation (Walker and Schneider, 2006; Schneider, 2006). In the limit Ro → 1, the upper branch of the Hadley circulation conserves angular momentum and is unaffected by eddy momentum fluxes; its strength responds directly to changes in thermal driving. This is the limit con- sidered in classical theories for the Hadley circulation, which provide expressions for its width and strength as a function of thermal and other parameters (Schneider, 1977; Held and Hou, 1980; Lindzen and Hou, 1988). In the limit Ro → 0, the strength of the Hadley circulation is controlled by eddy momentum fluxes; its strength responds to changes in ther- mal driving only insofar as they affect the eddy momentum fluxes (e.g., Dickinson, 1971). In between these limiting cases lie Hadley circulations with 0 < Ro < 1 in their upper branches, which respond to changes in thermal driving through changes in thermodynamic balances, in eddy momentum fluxes, and possibly in Rossby numbers. There is no theory that captures how the Hadley circulation responds to climate changes in this intermediate range of Rossby numbers.
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Differential reactivity in the pulmonary circulation

Differential reactivity in the pulmonary circulation

Measurements of lobar pulmonary artery or vein volume, total lobar blood volume, and the volume to the midpoint of lobar vascular resistance were made in the dog isolated lung lobe befor[r]

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CEREBRAL CIRCULATION AND METABOLISM IN HYPERTHYROIDISM

CEREBRAL CIRCULATION AND METABOLISM IN HYPERTHYROIDISM

This is an unexpected finding and suggests that either extracerebral contamination of cerebral venous blood has occurred, or that further observations on hyperthyroidism would actually r[r]

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THE HEMATOCRIT OF THE LESSER CIRCULATION IN MAN

THE HEMATOCRIT OF THE LESSER CIRCULATION IN MAN

These data would indicate, therefore, that in the pulmonary capillary bed of man no significant degree of axial streaming of red cells can be demonstrated by this method, and that the pu[r]

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TRANSPORTATION, CIRCULATION AND EXCRETION IN ORGANISMS.pdf

TRANSPORTATION, CIRCULATION AND EXCRETION IN ORGANISMS.pdf

• Transport of food from leaves to other parts of the plants is called translocation.. • Translocation of food is necessary to fulfill the daily • Translocation of food is necessary to[r]

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Water and Fine-Sediment Circulation

Water and Fine-Sediment Circulation

TREATISE ON ESTUARINE AND COASTAL SCIENCE EDITORS-IN-CHIEF Eric Wolanski James Cook University and Australian Institute of Marine Science, Townsville, QLD, Australia Donald McLusky Unive[r]

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Endothelin A receptors and the coronary circulation

Endothelin A receptors and the coronary circulation

Coronary collateral vessels can synthesise prostacyclin. Furthermore, in dogs with long-term coronary occlusion, prostacyclin appears to cause tonic collateral vessel dila- tation [25] because cyclooxygenase blockade with indo- methacin significantly decreased retrograde blood flow from the cannulated collateral dependent artery. Traverse, et al. [24] showed that prostacyclin production is impor- tant in blunting the vasoconstrictor effects of ET-1 in the collateral circulation. In contrast, the response of colla- teral vascular resistance to ET-1 in the normal zone was much less affected by inhibition of prostacyclin produc- tion. This is in agreement with previous findings that vasodilator prostaglandins are of greater importance in collateral than in normal coronary vessels.
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Fetal cells in the maternal circulation

Fetal cells in the maternal circulation

Certainly, feto-m aternal haem orrhage leading to transfusion of fetal cells is well documented throughout pregnancy at amniocentesis, CVS therapeutic and spontaneous m iscarriage, threatened m iscarriag e and during labour. However all these conditions arise in abnormal pregnancies or are iatrogenic. In normal, undisturbed pregnancies such haemorrhage has not been proven to occur and it is possible that fetal red cells are actively transferred to the m other as some m aternal lymphocytes gain access to the fetus. Fetal blood cells are formed initially in the yolk sac from 4 weeks' gestation, but do not circulate until the heart begins to beat at 5 weeks. Fetal vessels are not present within the chorionic villus stroma until 8 weeks. It is therefore unlikely that fetal blood elements would be able to escape into the maternal circulation as early as 5 weeks' gestation. Gan shirt et al (1994) have detected fetal erythroblasts in m aternal samples as early as the fifth week of gestation (though this was not an assisted conception pregnancy and so the gestation was not known
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THE WEATHER AND CIRCULATION OF JANUARY 1962

THE WEATHER AND CIRCULATION OF JANUARY 1962

flow overriding cold air in the lower layers. Lower than normal thickness ovc’r most of North America was associat>ed with the vigorous amplification at 700 mh. [r]

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STUDIES ON THE CIRCULATION IN THE NEONATAL PERIOD

STUDIES ON THE CIRCULATION IN THE NEONATAL PERIOD

Relationship of difference in oxygen saturation between pulmonary artery (PA) and mixed venous. blood (RV) to age of infants..[r]

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On the multiple-cell thermohaline circulation

On the multiple-cell thermohaline circulation

this produces a two-cell flow in the vertical direction with the salinity driven motion near the surface, and with the thermal cell of circulation near the bottom. The stream function ψ (y,z) distribution as multiple-cell circulation is shown in Figure 4 when Pr = ∞ and Pr = 10. The latter case (Pr = 10) corresponds to real sea water condition and reflects well an inclination of the zero- circulation line observed in the laboratory experiments under the surface forcing (Fig. 1a).

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