419 research outputs found
Mechanisms of Early Brain Morphogenesis
In structures with obvious mechanical function, like the heart and bone, the relationship of mechanical forces to growth and development has been well studied. In contrast, other than the problem of neurulation: formation of the neural tube), developmental mechanisms in the nervous system have received relatively little attention. The central aim of this research is to characterize the biophysical mechanisms that shape the early embryonic brain. Experiments were performed primarily in the chicken brain, which is morphologically similar to humans during early stages of development. Proposed mechanisms were tested using computational models to ensure that hypotheses are consistent with physical law. The brain initially forms as a straight epithelial tube in the embryo: approximately 3 weeks gestation in humans). We first investigated a potential role for mechanical feedback in regulating the development of this structure. We find that the neuroepithelium actively stiffens under decreased loading and softens under increased loading. Nuclear shapes are elongated in stiffer brains and circular in softer brains, consistent with changes in cytoskeletal contractility and wall stress. These results suggest a role for stress-based mechanical feedback in regulating epithelial development. We next investigated the more specific role of cytoskeletal contraction in forming the primary brain vesicles and rhombomeres that subdivide the primitive brain tube. We show that a combination of circumferential contraction in the boundary regions and isotropic contraction between boundaries can generate realistic vesicle morphologies, whereas longitudinal contraction between boundaries likely causes rhombomere formation. Models are used to show how regional variations in contraction may be a function of brain geometry and morphogenetic plasticity. As an extension of the previous study, we show that enhancing contractility in the embryonic chicken brain induces morphologies reminiscent of more primitive species such as frog and fish. In particular, brain cross sections that are relatively circular transform into diamonds, triangles, and narrow slits, shapes that are present in normal zebrafish and Xenopus brains at comparable stages of development. Models show that these shapes are likely produced by locally elevated cytoskeletal contraction, indicating a potential role for differential contractility in early brain development and evolution. In summary, results from this thesis should improve our understanding of the biophysical mechanisms that establish and regulate phenotype in the developing brain. The research begins to establish the framework necessary to connect early-stage mechanisms to interspecies differences in brain morphogenesis that occur during later development
Walery Pisarek's publications in "Zeszyty Prasoznawcze"
Artykuł dotyczy około 300 publikacji Walerego Pisarka, które ukazały się na łamach Zeszytów Prasoznawczych w okresie ponad sześciu dekad (1960-2017). Przez większość tego czasu W. Pisarek był związany etatowo z Ośrodkiem Badań Prasoznawczych (1962-2001), będąc jego dyrektorem w latach 1969-2000) bądź też kierował redakcją tego periodyku (1991-2012). Autor, analizując rozprawy i artykuły, ale także recenzje, sprawozdania i inne materiały zamieszczane w Zeszytach Prasoznawczych, ukazuje rozwój naukowy i rozszerzające się z biegiem lat zainteresowania badawcze Profesora Pisarka. Aby prześledzić rozległość tych zainteresowań, ich tematyka została umieszczona na osi czasu wyznaczającej węzłowe etapy kariery naukowej i życiowej Profesora. Publikacje w ZP pozostawały bowiem dość ściśle skorelowane z jego związkami z OBP i z Zeszytami. Gdy były to związki służbowe, publikacje w kwartalniku odzwierciedlały aktualny etap kariery i pełnione funkcje społeczne Profesora. Zaczynał od roli językoznawcy - badacza języka w prasie, by w czasach szefowania Ośrodkowi objąć naukowo praktycznie cały obszar badań nad komunikowaniem społecznym, a w okresie uniwersyteckim OBP - powrócił do socjolingwistyki (koncepcja "słów sztandarowych"). Cechą charakterystyczną publikacji w Zeszytach była równowaga pomiędzy tekstami o nastawieniu teoretycznym czy metodologicznym a pracami prezentującymi wyniki własnych badań empirycznych. Walery Pisarek przybliżał także polskiemu czytelnikowi literaturę światową (90 recenzji książek), omawiał zawartość zagranicznych periodyków naukowych, zwłaszcza amerykańskiego Journalism Quarterly, a wreszcie - przybliżał osiągnięcia światowego medioznawstwa (ponad 30 sprawozdań z zagranicznych kongresów i konferencji naukowych).The article presents an overview of approximately 300 publications by Walery Pisarek, which appeared in Zeszyty Prasoznawcze (Media Research Issues) over six decades (1960-2017). For most of this time, Walery Pisarek was a full-time researcher at the Press Research Centre (1962-2001), the Centre's director from 1969 to 2000, who managed the editorial office of Zeszyty Prasoznawcze from 1991-2012. The author of the article analyzed Professor Pisarek's dissertations and articles, but also reviews, reports and other materials published in Zeszyty Prasoznawcze, showing the scientific development and expanding research interests of Professor Pisarek over the years. To trace the extent of these interests, the publications' subjects were put on a timeline showing the most important stages of Walery Pisarek's career and life. His publications in Zeszyty Prasoznawcze were quite closely related to the Press Research Centre and the Centre's quarterly, and reflected the Professor's career and activities. He started as a linguist who studied press language, and later he covered almost all aspects of social communication during the time when he was the director of the Press Research Centre. When the Centre became a part of the Jagiellonian University, Professor Pisarek returned to sociolinguistics developing the "banner words". There is a noticeable balance between theoretical or methodological texts and those presenting the results of Walery Pisarek's empirical research, and that balance is a characteristic trait of Walery Pisarek's publications in Zeszyty Prasoznawcze. Walery Pisarek wrote about 90 reviews of books published in several languages, reviewed foreign academic journals, especially the American Journalism Quarterly, and published more than 30 reports from foreign congresses and scientific conferences organized abroad, introducing the concepts and issues discussed by world-famous media studies researchers to the Polish audience and media scholars
CHEK2 signaling is the key regulator of oocyte survival after chemotherapy.
Cancer treatments can damage the ovarian follicle reserve, leading to primary ovarian insufficiency and infertility among survivors. Checkpoint kinase 2 (CHEK2) deficiency prevents elimination of oocytes in primordial follicles in female mice exposed to radiation and preserves their ovarian function and fertility. Here, we demonstrate that CHEK2 also coordinates the elimination of oocytes after exposure to standard-of-care chemotherapy drugs. CHEK2 activates two downstream targets-TAp63 and p53-which direct oocyte elimination. CHEK2 knockout or pharmacological inhibition preserved ovarian follicle reserve after radiation and chemotherapy. However, the lack of specificity for CHEK2 among available inhibitors limits their potential for clinical development. These findings demonstrate that CHEK2 is a master regulator of the ovarian cellular response to damage caused by radiation and chemotherapy and warrant the development of selective inhibitors specific to CHEK2 as a potential avenue for ovario-protective treatments
Czy w Polsce jest miejsce na lokalną telewizję komercyjną? Doświadczenia i perspektywy
IS THERE ANY PLACE FOR LOCAL COMMERCIAL TELEVISION IN POLAND? EXPERIENCES AND PROSPECTS The article attempts to summarize more than two decades of the development of local commercial television in Poland. The initial spontaneous flowering of local earth station during the ‘piracy period’ (1990–1994), when 19 stations operated (including 12 within the network Polonia 1) was hampered by the regulator (KRRiT – the National Broadcasting Council) after the first licensing process (1994) when Polonia 1 was eliminated and 12 licences were granted. After two decades of changes, the market of ground stations consolidated (especially stations operating in western Poland known as TV Oder). Today there are only four broadcasters (however, TV Odra broadcasts in fi ve regional variants), the programs of local interest take only about 2 hours per day, and the remaining air time is used for retransmissions of programs of nationwide stations – TV4 or TVN. The future of the station after switch off (July 2013) is unclear, because none of these stations has a licence for digital broadcasting. Of the three competing satellite stations in 2008–2010 only one survived (Silesian TVS), but at the cost of reducing regional materials in favour of the universal content, especially entertainment. There are few examples of successful local programs in their own cable television (one of the glorious exception is Poznań WTK). The so-called local Internet TV is only the beginning of real television: such stations produce video content occasionally or once a week (which is short). However, in view of popularising the offer of twenty nationwide channels within the framework of digital terrestrial television in the near future (and plans to transform the public channel TVP Info into the one detached from its regional roots) the Internet will probably be the only enclave to continue the activities of local commercial television
The beginnings of press studies during the partitions and in the reborn Poland : Galician and Krakow tropes
The article is of a review nature. it deals with the beginnings of press studies and the gradual crystallization of press studies as a scientific discipline in Poland, conducted or published mainly, though not exclusively in the areas of Galicia and Małopolska. The author recalls - behind the works of Sylwester Dziki - pioneering research conducted in the Lviv and Krakow centers in the nineteenth century by several generations of professional bibliographers and historians (such as J.S. Bandtkie, K.J.T. Estreicher) and amateur enthusiasts (such as A. Chłędowski, K. Szajnocha, S.J.N. Czarnowski). At the beginning of the twentieth century, they took the form of broader organizational activities (S. Gorski, S.T. Jarkowski), in particular related to the implementation of the ideas adopted at the Krakow Congress of Journalists (1911) and implemented gradually after regaining independence, mainly by Jarkowski and his colleagues. The article shows the process of the institutionalization of Polish press studies in the dimension of journalistic education (especially at the academic level), the development of journalism integrating press researchers, and finally - a long-term fight for the establishment of a center researching the press. These three ideas materialized partly in the interwar period through the activities of, among others, the Academy of Journalism in Warsaw (1927-1939). However, they developed in a more mature form only after the second World War, with the establishment of the Polish institute of social sciences and the "Press Poland" industry monthly. In the following years, journalism studies at the University of Warsaw and Jagiellonian University as well as scientific journals like "the Press Studies Quarterly" (the body of the Press Research Institute in Warsaw) and "the Contemporary and Early Press" (related to the Press Research Centre in Krakow) were established
International jurisprudence and national law
The author offers two models of rethinking the society organization, and the place that law, especially international and human rights law, occupies in it
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