8,813 research outputs found
Ontogeny and Phylogeny of Brain Barrier Mechanisms.
No full textThe brain functions within an internal environment that is determined and controlled by morphological structures and cellular mechanisms present at interfaces between the brain and the rest of the body. In vertebrates these interfaces are across cerebral blood vessels (blood-brain barrier) choroid plexuses (blood-cerebrospinal fluid barrier) and pia-arachnoid. There is a CSF-brain barrier in the neuroepithelium lining the ventricular system that is only present in embryos. There is now substantial evidence that many brain barrier mechanisms develop early and that in some cases they are functionally more active and even more specialized compared to adult barriers. Therefore barriers in developing brain should be viewed as adapted appropriately for the growing brain and not, as is still widely believed, immature. Considerable advances in our understanding of these barrier mechanisms have come from studies of the developing brain and invertebrates. A striking aspect, to be highlighted in this special edition, is that many of the molecular mechanisms in these very diverse species are similar despite differences in the cellular composition of the interfaces. This Frontiers Topic comprises articles in three sections: Original studies, Reviews and Myths & Misconceptions. Original articles provide new information on molecular and cellular barrier mechanisms in developing brains of primates, including human embryos (Brøchner et al., Ek et al., Errede et al.), rodents (Bauer et al., Liddelow, Strazielle & Ghersi-Egea, Saunders et al., Whish et al.), chick (Bueno et al.) and zebrafish (Henson et al.) as well as studies in drosophila (Hindle & Bainton, De Salvo et al., Limmer et al.). The Reviews section includes evolutionary perspectives of the blood-brain and blood-CSF barriers (Bueno et al., Bill & Korzh). There are also detailed reviews of the current state of understanding of different interfaces and their functional mechanisms in developing brain (Bauer et al., Strazielle & Gjersi-Egea, Liddelow, Richardson et al., Errede et al., Henson et al., Brøchner et al.) and in invertebrates (Hindle & Bainton, De Salvo et al., Limmer et al). Different aspects of the relationship between properties of the internal environment of the brain and its development are discussed. (Stolp & Molnar, Johansson, Prasongchean et al.). A neglected area, namely barriers over the surface of the brain during development is also covered (Brøchner et al.). Clinically related perspectives on barrier disruption in neonatal stroke are provided by Kratzer et al. and other aspects of dysfunction by Morretti et al. and by Palmeta et al. on the continuing problem of bilirubin toxicity. Progress in this field is hampered by many prevailing myths about barrier function, combined with methodologies that are not always appropriately selected or interpreted. These are covered in the Misconceptions, Myths and Methods section, including historical aspects and discussion of the paracellular pathway, a central dogma of epithelial and endothelial biology (Saunders et al.) and a review of markers used to define brain barrier integrity in development and in pathological conditions (Saunders et al.). Use of inappropriate markers has caused considerable confusion and unreliable interpretation in many published studies. Torbett et al. deal with the complexities of the new field of applying proteomics to understanding blood-brain barrier properties as do Huntley at al. with respect to applying modern high throughput gene expression methods (Huntley et al.). The Editorial summarizes the contributions from all authors. This includes mention of some the main unanswered but answerable questions in the field and what the impediments to progress may be
The expedition of the Sultan in 1538 in Moldavia : (in the view of an Italian author)
No full textThe expedition of the Sultan in 1538 in Moldavia : (in the view of an Italian author). - In: Colloquia, an 2006, vol. 13, nr. 1-2, p. 257-271
5G NR : the next generation wireless access technology /
No full text5G NR: The Next Generation Wireless Access TechnologyïŽfollows the authors' highly celebrated books on 3G and 4G by providing a new level of insight into 5G NR. After an initial discussion of the background to 5G, including requirements, spectrum aspects and the standardization timeline, all technology features of the first phase of NR are described in detail. Included is a detailed description of the NR physical-layer structure and higher-layer protocols, RF and spectrum aspects and co-existence and interworking with LTE. The book provides a good understanding of NR and the different NR technology components, giving insight into why a certain solution was selected. Content includes: Key radio-related requirements of NR, design principles, technical featuresDetails of basic NR transmission structure, showing where it has been inherited from LTE and where it deviates from it, and the reasons whyNR Multi-antenna transmission functionalityDetailed description of the signals and functionality of the initial NR access, including signals for synchronization and system information, random access and pagingLTE/NR co-existence in the same spectrum, the benefits of their interworking as one systemThe different aspects of mobility in NR RF requirements for NR will be described both for BS and UE, both for the legacy bands and for the new mm-wave bands.Includes bibliographical references and index.Vendor-supplied metadata.5G NR: The Next Generation Wireless Access TechnologyïŽfollows the authors' highly celebrated books on 3G and 4G by providing a new level of insight into 5G NR. After an initial discussion of the background to 5G, including requirements, spectrum aspects and the standardization timeline, all technology features of the first phase of NR are described in detail. Included is a detailed description of the NR physical-layer structure and higher-layer protocols, RF and spectrum aspects and co-existence and interworking with LTE. The book provides a good understanding of NR and the different NR technology components, giving insight into why a certain solution was selected. Content includes: Key radio-related requirements of NR, design principles, technical featuresDetails of basic NR transmission structure, showing where it has been inherited from LTE and where it deviates from it, and the reasons whyNR Multi-antenna transmission functionalityDetailed description of the signals and functionality of the initial NR access, including signals for synchronization and system information, random access and pagingLTE/NR co-existence in the same spectrum, the benefits of their interworking as one systemThe different aspects of mobility in NR RF requirements for NR will be described both for BS and UE, both for the legacy bands and for the new mm-wave bands.Elsevie
What is your diagnosis? Radiographic diagnosis - Soft-tissue opacity containing numerous gas pockets in the right cranioventral abdominal region
No full textPT: J; CR: KONDE LJ, 1989, VET RADIOL, V30, P41 NEATH PJ, 1997, J SMALL ANIM PRACT, V38, P387 OBRIEN TR, 1978, RADIOGRAPHIC DIAGNOS, P376 SAUNDERS HM, 1998, VET RADIOL ULTRASOUN, V39, P349 STICKLE RL, 1989, J AM VET MED ASSOC, V194, P103; NR: 5; TC: 0; J9: J AMER VET MED ASSN; PG: 2; GA: 537CASource type: Electronic(1
Inleidende studie betreffende de mogelijkheden tot verhoging van de Emmapolderdijk
No full textDe onderhavige nota is ontstaan als uitvloeisel van voorstellen van de afdelingsingenieur voor de afdeling Landaanwinningswerken aan de Hoofdingenieur-Direkteur in de direktie Groningen betreffende het opzetten van een proef met golfremmende elementen op de Emmapolderdijk, van de daarop gevolgde gedachtenwisseling, en van de brief nr. 4048 van 3 juli 1963 van de genoemde Hoofdingenieur-Direkteur, waarin aan de afdeling Landaanwinningswerken werd opgedragen voorstudieste verrichten omtrent de mogelijkheden tot verhoging van de Emmapolderdijk
Ex-ante evaluation of tightening environmental policy: the case of mineral use in Dutch agriculture
No full textNon-point source pollution is notoriously difficult to asses. A relevant example is mineral emissions in the Netherlands. Since the mid 1980s the Dutch government has sought to reduce emissions through a wide variety of measures, the effect of which in turn is monitored using modeling techniques. This paper presents the current generation of mineral emission models from agriculture based on microsimulation of farms in combination with a spatial equilibrium model for the dispersion of manure from excess regions with high livestock intensities within the country to areas with low livestock intensities. The micro-simulation approach retains the richness in the heterogeneity of farm household decision making that are the core cause of the difficulty of assessing non-point source pollution, while using the best available data to track corresponding pollution. Using scenario analysis we are able to assess the possible effects of further tightening of agro-environmental policy.micro-simulation, spatial-equilibrium model, non-point source pollution, Environmental Economics and Policy,
Single Farm Payment in the European Union and its Implications on New Zealand Dairy and Beef Trade
No full textThe 2003 reform of the European Union's Common Agricultural Policy (CAP) replaced the coupled direct support schemes by a Single Farm Payment (SFP), which will be mainly delivered to farmers irrespective of what they produce (hence 'decoupled' from production). The level of decoupling differs among the Member States. This paper assesses the implementation of the SFP across Member States and how far it has been decoupled. The expected changes in the European Union's and New Zealand's trade in dairy products and beef resulting from the 2003 reform of the CAP are simulated, using a partial equilibrium trade model (Lincoln Trade and Environment Model; LTEM).Single Farm Payment, European Union, New Zealand, Common Agricultural Policy, Direct payments, Agricultural and Food Policy, International Relations/Trade,
Cerebrospinal fluid supports viability and proliferation of cortical cells in vitro, mirroring in vivo development.
No full textBackground The central nervous system develops around a fluid filled compartment. Recently, attention has turned to the potential role of the fluid (cerebrospinal fluid, CSF) in the developmental process. In particular, the cerebral cortex develops from the germinal epithelium adjacent to the CSF with regulation of cell proliferation and differentiation provided by cells adjacent to the fluid-filled subarachnoid space. Methods Histological analysis of fetal rat cortical sections was used to follow the extent of in vivo cortical development. A quantitative analysis of proliferation and migration of cortical cells at E17 – E21 was obtained through immunocytochemical staining of bromodeoxyuridine (BrdU) -labelled cells. In vitro studies were performed on primary cortical cells at days E17-E20, maintained in either Neurobasal media or 100% fetal rat CSF for 72 h before analysis of proliferation. Results The proliferation potential of primary cortical cells varied depending on the age of extraction. E17 and E20 cells showed little proliferation while E18 and E19 cell showed the maximum. The CSF from fetuses of all ages tested, except E21, was able to maintain primary cortical cells from the developing fetus in vitro and to stimulate and support their proliferation in the absence of any additions. E17 cells showed little proliferation in any media while E19 cells showed maximum proliferation in E19 and E20 CSF. Conclusion CSF composition most probably changes with age, as does the proliferation potential of cells in the developing cerebral cortex. CSF alone supports viability as well as proliferation of cortical cells. CSF must therefore be regarded as an important environmental influence in brain development and can be used in vitro to maintain both the viability of cortical progenitor cells and their age-related proliferative potential
Finnmarksloven er vedtatt. Om de vesentligste endringene i loven i forhold til regjeringens lovforslag i Ot.prp. nr 53 (2002-2003)
No full textThe Finnmark Act was recently approved in the parliament by a clear majority. A half-century discussion
concerning land rights of the Saami people has culminated in an Act concerning the «right to
land and water» in Finnmark County. The legislative history of the Act covers approximately 25
years, and started when the Saami Law committee was appointed in autumn 1980.
In this paper the author examines this legislative history, emphasizing the main changes in the
adopted act in relation the disputed bill to the parliament in spring 2003 (Ot.prp. nr. 53 (2002-2003).
Pursuant to the Act, a land commission and special tribunal will be established that will clarify
and settle land rights questions. The author observes that the land consolidation court, as proposed
by the Saami Law committee, is not given any place in the Act.
Finally, the author remarks that the changes from the bill of 2003, up to the adoption of the Act in
June this year, have led to an act which is a major step forward in giving the people in Finnmark
County rights to their natural resources and common land. The Act also represents strong support
for the land rights of the Saami people
Farming on the Edge in Poland. Options for Improving Farm Incomes for the Main Types of Farms after Joining the EU
No full textThe aim of the paper is to examine the financial impacts of introducing the Common Agricultural Policy into the Polish farming sector after the accession to the EU. Aggregated results from farm level modelling using linear programming for 210 farm types representing the variety of Polish farms, and 90% of the agricultural sector are presented. The benefits of the negotiated subsidy arrangements are unequally distributed and only a partial solution to low farm family incomes.EU accession, Polish Agriculture, direct payments, typical farms, farm model., Farm Management,
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