949 resultados para Transport Surveys
Resumo:
In vertebrates, early brain development takes place at the expanded anterior end of the neural tube, which is filled with embryonic cerebrospinal fluid (E-CSF). We have recently identified a transient blood-CSF barrier that forms between embryonic days E3 and E4 in chick embryos and that is responsible for the transport of proteins and control of E-CSF homeostasis, including osmolarity. Here we examined the presence of glucose transporter GLUT-1 as well the presence of caveolae-structural protein Caveolin1 (CAV-1) in the embryonic blood-CSF barrier which may be involved in the transport of glucose and of proteins, water and ions respectively across the neuroectoderm. In this paper we demonstrate the presence of GLUT-1 and CAV-1 in endothelial cells of blood vessels as well as in adjacent neuroectodermal cells, located in the embryonic blood-CSF barrier. In blood vessels, these proteins were detected as early as E4 in chick embryos and E12.7 in rat embryos, i.e. the point at which the embryonic blood-CSF barrier acquires this function. In the neuroectoderm of the embryonic blood-CSF barrier, GLUT-1 was also detected at E4 and E12.7 respectively, and CAV-1 was detected shortly thereafter in both experimental models. These experiments contribute to delineating the extent to which the blood-CSF embryonic barrier controls E-CSF composition and homeostasis during early stages of brain development in avians and mammals. Our results suggest the regulation of glucose transport to the E-CSF by means of GLUT-1 and also suggest a mechanism by which proteins are transported via transcellular routes across the neuroectoderm, thus reinforcing the crucial role of E-CSF in brain development.
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Tällä hetkellä haastavin telekommunikaatioteollisuuden tutkimus – ja kehitystoiminta on keskittynyt kolmannen sukupolven matkapuhelinjärjestelmien ympärille. Järjestelmien standardointityössä on saatu aikaiseksi ensimmäiset vakaat spesifikaatioversiot ja kaupallista toimintaa ollaan parhaillaan aloittelemassa Japanissa ja Euroopassa. Eräs kolmannen sukupolven järjestelmistä on UMTS (Universal Mobile Telecommunications System). Tämä diplomityö antaa yleiskuvan UMTS järjestelmästä ja sen eri verkkoelementtien toiminnallisuuksista. Päähuomio on kiinnitetty radioverkkojärjestelmään (UMTS Terrestrial Radio Access Network) ja erityisesti sen radioaliverkkojärjestelmään (Radio Network Subsystem), joka koostuu radioverkonohjaimesta (Radio Network Controller) ja joukosta siihen kuuluvia tukiasemia (Node B). Radioverkonohjain ja tukiasemat on yhdistetty avoimen rajapinnan kautta jota kutsutaan Iub -rajapinnaksi. Rajapinta tarjoaa radioverkonohjaimelle mahdollisuuden kontrolloida tukiasemia signalointiviestien avulla ja mahdollistaa tehokkaan ja luotettavan käyttäjätiedon siirron radioaliverkkojärjestelmän sisällä. Tämän diplomityön pääasiallinen sisältö on siirtoresurssien hallinta Iub -rajapinnan ylitse. Työssä esitellään ja selitetään siirtoverkon arkkitehtuuri. Myös kaikki Iub:ssä sijaitsevat protokollat ja toiminnalliset yksiköt jotka vaikuttavat siirtoresurssien hallintaan esitellään ja kuvataan yksityiskohtaisesti. Päähuomio on kiinnitetty sovellusprotokolliin sekä rajapinnan siirtoverkko- että radioverkkokerroksella sekä näiden protokollien väliseen vuorovaikutukseen. Kyseiset protokollat ovat Node B Application Part (NBAP) ja Access Link Control Application Part (ALCAP). Työn toteutusosassa käydään lävitse NBAP –protokollan prototyypin ja Node B Manager –toiminnallisen yksikön prototyypin implementaatio.
Resumo:
We present an analysis of factors influencing carrier transport and electroluminescence (EL) at 1.5 µm from erbium-doped silicon-rich silica (SiOx) layers. The effects of both the active layer thickness and the Si excess content on the electrical excitation of erbium are studied. We demonstrate that when the thickness is decreased from a few hundred to tens of nanometers the conductivity is greatly enhanced. Carrier transport is well described in all cases by a Poole-Frenkel mechanism, while the thickness-dependent current density suggests an evolution of both density and distribution of trapping states induced by Si nanoinclusions. We ascribe this observation to stress-induced effects prevailing in thin films, which inhibit the agglomeration of Si atoms, resulting in a high density of sub-nm Si inclusions that induce traps much shallower than those generated by Si nanoclusters (Si-ncs) formed in thicker films. There is no direct correlation between high conductivity and optimized EL intensity at 1.5 µm. Our results suggest that the main excitation mechanism governing the EL signal is impact excitation, which gradually becomes more efficient as film thickness increases, thanks to the increased segregation of Si-ncs, which in turn allows more efficient injection of hot electrons into the oxide matrix. Optimization of the EL signal is thus found to be a compromise between conductivity and both number and degree of segregation of Si-ncs, all of which are governed by a combination of excess Si content and sample thickness. This material study has strong implications for many electrically driven devices using Si-ncs or Si-excess mediated EL.
Resumo:
The membrane-bound serine protease CAP2/Tmprss4 has been previously identified in vitro as a positive regulator of the epithelial sodium channel (ENaC). To study its in vivo implication in ENaC-mediated sodium absorption, we generated a knockout mouse model for CAP2/Tmprss4. Mice deficient in CAP2/Tmprss4 were viable, fertile, and did not show any obvious histological abnormalities. Unexpectedly, when challenged with sodium-deficient diet, these mice did not develop any impairment in renal sodium handling as evidenced by normal plasma and urinary sodium and potassium electrolytes, as well as normal aldosterone levels. Despite minor alterations in ENaC mRNA expression, we found no evidence for altered proteolytic cleavage of ENaC subunits. In consequence, ENaC activity, as monitored by the amiloride-sensitive rectal potential difference (ΔPD), was not altered even under dietary sodium restriction. In summary, ENaC-mediated sodium balance is not affected by lack of CAP2/Tmprss4 expression and thus, does not seem to directly control ENaC expression and activity in vivo.
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The electrical and electroluminescence (EL) properties at room and high temperatures of oxide/ nitride/oxide (ONO)-based light emitting capacitors are studied. The ONO multidielectric layer is enriched with silicon by means of ion implantation. The exceeding silicon distribution follows a Gaussian profile with a maximum of 19%, centered close to the lower oxide/nitride interface. The electrical measurements performed at room and high temperatures allowed to unambiguously identify variable range hopping (VRH) as the dominant electrical conduction mechanism at low voltages, whereas at moderate and high voltages, a hybrid conduction formed by means of variable range hopping and space charge-limited current enhanced by Poole-Frenkel effect predominates. The EL spectra at different temperatures are also recorded, and the correlation between charge transport mechanisms and EL properties is discussed.
Resumo:
Tämän tutkielman tarkoituksena on selvittää suomalaisen kartonkikuljetuspakkausfirman, Eltete TPM Oy:n, tulevaisuudennäkymät selvittämällä voiko puisen kuljetuspakkausmateriaalin korvata kartonkisilla materiaaleilla. Kyseinen tutkimus suoritetaan selvittämällä toimialanmuutokseen vaikuttavia tekijöitä kuten ostokäyttäytymistä, innovaation ominaisuuksia, säädöksiä, kilpailuympäristöä sekä lopuksi tutkimalla mitä kuljetuspakkauksien asiakkaat haluavat ja tarvitsevat. Kyseisen tutkimuksen kohdeasiakkaiksi valittiin suurimmat kodinkoneyritykset Euroopassa ja tutkimusmenetelmäksi postikysely. Suoritetun markkinointitutkimuksen tulokset kodinkoneyritysten pakkausratkaisuista sekä kilpailija-analyysi osoittivat, että todella on olemassa kasvava kysyntä kierrätettäville kartonkisille kuljetuspakkausratkaisuille, kuten Eltete TPS - Framepack solution on, sekä että Eltete TPM Oy:llä on voimavaroja tulevaisuudessa nousta markkinajohtajaksi muuttuvalla kuljetuspakkaussektorilla.
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Hydrogenated nanocrystalline silicon (nc-Si:H) obtained by hot-wire chemical vapour deposition (HWCVD) at low substrate temperature (150 °C) has been incorporated as the active layer in bottom-gate thin-film transistors (TFTs). These devices were electrically characterised by measuring in vacuum the output and transfer characteristics for different temperatures. The field-effect mobility showed a thermally activated behaviour which could be attributed to carrier trapping at the band tails, as in hydrogenated amorphous silicon (a-Si:H), and potential barriers for the electronic transport. Trapped charge at the interfaces of the columns, which are typical in nc-Si:H, would account for these barriers. By using the Levinson technique, the quality of the material at the column boundaries could be studied. Finally, these results were interpreted according to the particular microstructure of nc-Si:H.
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Results from quantitative surveys enable historians, sociologists and demographers to describe and analyse the evolution of sport participation in France from 1967 to 2010. However, most of these social scientists use the results of these surveys to create very different methodologies without having studied the surveys' empirical data or databases. In this article, we demonstrate how we have attempted to establish a basis for comparability of the surveys by analysing these databases. As a result of our work, certain affirmations on which the history of sport participation in France has long been based may be called into question or even changed.
Resumo:
The origin of Spanish regional economic divergence can be traced back at least until the seventeenth century, although its full definition took place during industrialisation. Historians have often included uneven regional infrastructure endowments among the factors that explain divergence among Spanish regions, although no systematic analysis of the spatial distribution of Spanish infrastructure and its determinants has been carried out so far. This paper aims at filling that gap, by offering a description of the regional distribution of the main Spanish transport infrastructure between the middle of the nineteenth century and the Civil War. In addition, it estimates a panel data model to search into the main reasons that explain the differences among the Spanish regional endowments of railways and roads during that period. The outcomes of that analysis indicate that both institutional factors and the physical characteristics of each area had a strong influence on the distribution of transport infrastructure among the Spanish regions.
Resumo:
All social surveys suffer from different types of errors, of which one of the most studied is non-response bias. Non-response bias is a systematic error that occurs because individuals differ in their accessibility and propensity to participate in a survey according to their own characteristics as well as those from the survey itself. The extent of the problem heavily depends on the correlation between response mechanisms and key survey variables. However, non-response bias is difficult to measure or to correct for due to the lack of relevant data about the whole target population or sample. In this paper, non-response follow-up surveys are considered as a possible source of information about non-respondents. Non-response follow-ups, however, suffer from two methodological issues: they themselves operate through a response mechanism that can cause potential non-response bias, and they pose a problem of comparability of measure, mostly because the survey design differs between main survey and non-response follow-up. In order to detect possible bias, the survey variables included in non-response surveys have to be related to the mechanism of participation, but not be sensitive to measurement effects due to the different designs. Based on accumulated experience of four similar non-response follow-ups, we studied the survey variables that fulfill these conditions. We differentiated socio-demographic variables that are measurement-invariant but have a lower correlation with non-response and variables that measure attitudes, such as trust, social participation, or integration in the public sphere, which are more sensitive to measurement effects but potentially more appropriate to account for the non-response mechanism. Our results show that education level, work status, and living alone, as well as political interest, satisfaction with democracy, and trust in institutions are pertinent variables to include in non-response follow-ups of general social surveys. - See more at: https://ojs.ub.uni-konstanz.de/srm/article/view/6138#sthash.u87EeaNG.dpuf
Resumo:
Spain’s transport infrastructure policy has become a paradigmatic case of oversupply and of mismatch with demand. The massive expansion of the country’s transport infrastructure over the last decade has not been a response to demand bottlenecks or previously identified needs. For this reason, the intensity of use today on all interurban modes of transport in Spain falls well below that of other EU countries. This paper analyzes the institutional and regulatory factors that have permitted this policy, allowing us to draw lessons from the Spanish case that should help other countries avoid the pitfalls and shortcomings of Spanish policy.