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Wyszukujesz frazę "Megan, M." wg kryterium: Autor


Tytuł:
Polynomial stability of evolution operators in Banach spaces
Autorzy:
Megan, M.
Ceausu, T.
Ramneantu, M. L.
Tematy:
evolution operator
polynomial stability
exponential stability
Pokaż więcej
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Powiązania:
https://bibliotekanauki.pl/articles/254941.pdf  Link otwiera się w nowym oknie
Opis:
The paper considers three concepts of polynomial stability for linear evolution operators which are defined in a general Banach space and whose norms can increase not faster than exponentially. Our approach is based on the extension of techniques for exponential stability to the case of polynomial stability. Some illustrating examples clarify the relations between the stability concepts considered in paper. The obtained results are generalizations of well-known theorems about the uniform and nonuniform exponential stability.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Migrating songbirds on stopover prepare for, and recover from, oxidative challenges posed by long-distance flight
Autorzy:
McWilliams, Scott R.
Goymann, Wolfgang
Skrip, Megan M.
Fusani, Leonida
Alan, Rebecca R.
Bauchinger, Ulf
Cardinale, Massimiliano
Opis:
Managing oxidative stress is an important physiological function for all aerobic organisms, particularly during periods of prolonged high metabolic activity, such as long-distance migration across ecological barriers. However, no previous study has investigated the oxidative status of birds at different stages of migration and whether that oxidative status depends on the condition of the birds. In this study, we compared (1) energy stores and circulating oxidative status measures in (a) two species of Neotropical migrants with differing migration strategies that were sampled at an autumn stopover site before an ecological barrier; and (b) a species of trans-Saharan migrant sampled at a spring stopover site after crossing an ecological barrier; and (2) circulating oxidative measures and indicators of fat metabolism in a trans-Saharan migrant after stopovers of varying duration (0–8 nights), based on recapture records. We found fat stores to be positively correlated with circulating antioxidant capacity in Blackpoll Warblers and Red-eyed Vireos preparing for fall migration on Block Island, USA, but uncorrelated in Garden Warblers on the island of Ponza, Italy, after a spring crossing of the Sahara Desert and Mediterranean Sea. In all circumstances, fat stores were positively correlated with circulating lipid oxidation levels. Among Garden Warblers on the island of Ponza, fat anabolism increased with stopover duration while oxidative damage levels decreased. Our study provides evidence that birds build antioxidant capacity as they build fat stores at stopover sites before long flights, but does not support the idea that antioxidant stores remain elevated in birds with high fuel levels after an ecological barrier. Our results further suggest that lipid oxidation may be an inescapable hazard of using fats as the primary fuel for flight. Yet, we also show that birds on stopover are capable of recovering from the oxidative damage they have accrued during migration, as lipid oxidation levels decrease with time on stopover. Thus, the physiological strategy of migrating songbirds may be to build prophylactic antioxidant capacity in concert with fuel stores at stopover sites before a long-distance flight, and then repair oxidative damage while refueling at stopover sites after long-distance flight.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Air pollution and cortical myelin T1w/T2w ratio estimates in school-age children from the ABCD and NeuroSmog studies
Autorzy:
de Jesus, Alethea V.
Kossowski, Bartosz
Ahmadi, Hedyeh
Rutkowska, Emilia
Baumbach, Clemens
Kaczmarek-Majer, Katarzyna
Mysak, Yarema
Grellier, James
Herting, Megan M.
Szwed, Marcin
Skotak, Krzysztof
Degórska, Anna
Sitnik-Warchulska, Katarzyna
Lipowska, Małgorzata
Markevych, Iana
Opis:
Air pollution affects human health and may disrupt brain maturation, including axon myelination, critical for efficient neural signaling. Here, we assess the impact of prenatal and current long-term particulate matter (PM) and nitrogen dioxide (NO$_{2}$) exposure on cortical T1w/T2w ratios – a proxy for myelin content – in school-age children from the Adolescent Brain Cognitive Development (ABCD) Study (United States; N = 2021) and NeuroSmog study (Poland; N = 577), using Siemens scanners. Across both samples, we found that NO$_{2}$ and PM were not significantly associated with cortical T1w/T2w except for one association of PM$_{10}$ with lower T1w/T2w in the precuneus in NeuroSmog. Superficially, ABCD Study analyses including data from all scanner types (Siemens, GE, Philips; N = 3089) revealed a negative association between NO$_{2}$ exposure and T1w/T2w ratios. However, this finding could be an artifact of between-site sociodemographic differences and large scanner-type-related measurement differences. While significant associations between air pollution and cortical myelin were largely absent, these findings do not rule out the possibility that air pollution affects cortical myelin during other exposure periods/stages of neurodevelopment. Future research should examine these relationships across diverse populations and developmental periods using unified analysis methods to better understand the potential neurotoxic effects of air pollution.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Design and Validation of a Tool to Collect Student-Athletes Perception of Their Satisfaction
Autorzy:
Palao, Josè M.
Jost, Bridget
Katzer, Janel
Parietti, Megan
Tematy:
college
sport
tool
student-athlete
perception
Pokaż więcej
Wydawca:
Uniwersytet Szczeciński. Wydawnictwo Naukowe Uniwersytetu Szczecińskiego
Powiązania:
https://bibliotekanauki.pl/articles/24202857.pdf  Link otwiera się w nowym oknie
Opis:
The purpose of this study was to design and validate a tool to collect the student-athletes' perception of their satisfaction. The instrument collects information regarding student-athlete characteristics, self-perception, perception of training, perception of team/teammates, perception of the program organization, and perception of the support received. The design and validation, of the questionnaire were done in two phases: a) design and development of the instrument, and b) content validation by experts. The results show that the tool is suitable for obtaining information about student-athletes' perception of their satisfaction. The implementation of the tool involves two phases: a) student-athletes completion of a survey and b) student-athletes and moderator carry out a group discussion regarding the causes behind their answers, things to maintain, and things that could change or improve. The tool developed and validated could contribute to increase the information of student-athletes about their experience and generate communication channels.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The conserved and high K-to-Na ratio in sunflower pollen : possible implications for bee health and plant-bee interactions
Autorzy:
Wratten, Steve D.
Shields, Morgan W.
Grainger, Megan N. C.
Filipiak, Michał
Cairns, Sarah M.
Opis:
Sodium (Na) concentrations are low in plant tissues, and its metabolic function in plants is minor; however, Na is a key nutrient for plant consumers. Previous studies have thus far focused on Na concentration. Nevertheless, a balanced potassium (K) to Na ratio (K:Na) is more important than Na concentration alone since food with high K:Na has detrimental effects on consumers irrespective of Na concentration. Therefore, plants may actively regulate K:Na in their tissues and products, shaping plant-insect interactions. Studies considering nutritional aspects of plant-insect interactions have focused on nonreproductive tissues and nectar. In this study, we consider pollen as serving a primary reproductive function for plants as well as a food of pollinivores. Plants might regulate K:Na in pollen to affect their interactions with pollinivorous pollinators. To investigate whether such a mechanism exists, we manipulated Na concentrations in soil and measured the proportion of K, Na, and 13 other nutrient elements in the pollen of two sunflower (Helianthus annuus) cultivars. This approach allowed us to account for the overall nutritional quality of pollen by investigating the proportions of many elements that could correlate with the concentrations of K and Na. Of the elements studied, only the concentrations of Na and K were highly correlated. Pollen K:Na was high in both cultivars irrespective of Na fertilization, and it remained high regardless of pollen Na concentration. Interestingly, pollen K:Na did not decrease as pollen increased the Na concentration. We hypothesize that high K:Na in pollen might benefit plant fertilization and embryonic development; therefore, a tradeoff might occur between producing low K:Na pollen as a reward for pollinators and high K:Na pollen to optimize the plant fertilization process. This is the first study to provide data on pollen K:Na regulation by plants. Our findings broaden the understanding of plant-bee interactions and provide a foundation for a better understanding of the role of the soil-plant-pollen-pollinator pathway in nutrient cycling in ecosystems. Specifically, unexplored costs and tradeoffs related to balancing the K:Na by plants and pollinivores might play a role in past and current shaping of pollination ecology.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Hemifacial asymmetries in age perception: the left cheek looks older for females, but not males
Autorzy:
Lindell, Annukka K
Cianchetta, Rhiannon O
Azim, Sana M
Freeman, Cody G
de Oliveira, Nicole C
Saban, Sakire
Messina, Julia L
Wilson, Kira Elise
Egan, Alanna
Caspar, Megan D
Grey, Emma J
McDonald, Bryce A
Croxford, Kylie N
Bui, Thu Trang
Aiello, Ashley A
Heywood-Smith, Victoria M
Kidd, Andrew J
Stanley, Shenae C
Wakeling, Alarna
Hoggan, Stephanie A.L
Morriss, Ashleigh S
Trinh, Thi Phuong Mai
Thai-Nguyen, Hong
Fonte, Melissa
Agolli, Franceska
Tematy:
emotion
asymmetry
hemisphere
laterality
age
Pokaż więcej
Wydawca:
Fundacja Edukacji Medycznej, Promocji Zdrowia, Sztuki i Kultury Ars Medica
Powiązania:
https://bibliotekanauki.pl/articles/2106020.pdf  Link otwiera się w nowym oknie
Opis:
The left hemiface expresses emotion more intensely than the right. Because emotional expressions contract the facial muscles and wrinkle the skin, theoretically the left hemiface’s greater expressivity should prompt more pronounced expression lines and wrinkles on the left than right side of the face. As wrinkles are the most salient age cue, we investigated whether the left hemiface consequently appears older than the right. Two hundred and sixty participants (F=148; M=112) viewed booklets containing pairs of left-left and right-right chimeric faces of eight models (M=F). For each trial participants were asked to make a two alternative forced choice response indicating which image looked older. Results confirmed a left cheek bias, with participants more likely to select left-left than right-right chimeras. Whilst participant gender did not influence perceptions, model gender predicted cheek selections: responses to female models drive the overall left cheek bias. The left cheek (56.8%) appeared older than the right cheek (43.2%) for female models, whereas there was little difference in perceived age between male models' left (50.8%) and right (49.2%) cheeks. Given that youth influences perceptions of female beauty, these findings complement previous research and offer a potential explanation for why the left side of females’ faces are judged less attractive: the right cheek appears younger.
Dostawca treści:
Biblioteka Nauki
Artykuł

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