1,210 research outputs found
Space station Platform Management System (PMS) replanning using resource envelopes
One of the responsibilities of the Space Station Platform Management System (PMS) is to maintain constraint-free, short-term plans for platform and free-flyer activities. Both the replanning function and the associated constraint-checking function are viewed as potentially requiring expert system assistance. The PMS Resource Envelope Scheduling System (PRESS) expert system, which is currently under development, is described. The PRESS capabilities will include the following: plan, replan, and perform constraint checking using resource envelopes resembling those required for telescience; initialize itself using the results fo a previous run; infer the replanning needs associated with a change in resource availability; allow the user to determine the level of interaction (including an advisory capability) with the system during execution; and generate both a graphic timeline and a report as output. The PRESS is being developed on an IBM PC/AT using TeKnowledge, Inc.'s M.1 expert system shell. The PRESS activity definitions and constraints are based on those defined for the Cosmic Background Explorer (COBE) mission scheduled for launch in early 1989
Late miocene and early pliocene palaeoceanography at the eastern equatorial Pacific IODP Site U1338: implications for climate evolution and stability
The short-term background climate variability during the climatically stable latest Miocene to early Pliocene (LM-EP) is not well understood, owing to the lack of continuous, high-resolution climate records. Assessing variability during an interval of long-term climatic stability will constrain how sensitivity of major Earth’s system components (Earth system response - ESR) to external radiative forcing has changed through time.
This study investigated LM-EP climate, focussing on changes in ESR, El-Nino-Southern-Oscillation state, glacio-eustacy and the Messinian Salinity Crisis (MSC), and the origin of the Late Miocene Carbon Isotope Shift (LMCIS). This project produced the first high-resolution benthic foraminiferal δ18O and δ13C record in the eastern equatorial Pacific (IODP Site U1338) from 8.0-3.5 Ma that resolves all Milankovitch cyclicities. A high-resolution, orbitally-based age model, planktic foraminiferal δ18O, δ13C and Mg/Ca, coccolith-rich ‘clumped isotopes’ Δ47, spectral analyses and multi-site benthic foraminiferal isotope compilations were also produced.
Planktic foraminiferal Mg/Ca sea surface temperatures (SSTs) were ~25 °C. Coccolith-rich Δ47 temperatures were unrealistically cold at ~10-15 °C, reflecting moderate coccolith preservation and vital effects that cause higher Δ47.
Site U1338 and 982 combined benthic foraminiferal (δ18O; δ13C) wavelet analyses show moderate ESR from 6.3–4.7 Ma and after 3.7 Ma, but lower ERS from 7.0–6.3 Ma. The δ18O-minimum stage ~5.33 Ma, during long-term minimum δ18O, suggests that glacio-eustacy played a role in the MSC termination. The benthic foraminiferal δ13C compilation confirms that the LMCIS was globally synchronous and caused by a negative shift in oceanic reservoir δ13C, driven by changes in the continental carbon flux (increased sea-floor-spreading / C4-grass expansion).
Data syntheses show that global warmth, dominant El-Nino state, high cryosphere sensitivity, lower ice volume and short-term ice sheet variations characterised the LM-EP pre-7.0 and post-5.7 Ma. Stable conditions occurred ~7.0-5.7 Ma, with dominant La-Nina, higher ice volume, low cryosphere sensitivity and lower SSTs.Open Acces
Data report: late Miocene to early Pliocene coccolithophore and foraminiferal preservation at Site U1338 from scanning electron microscopy
The late Miocene to early Pliocene carbonate-rich sediments recovered at Integrated Ocean Drilling Program (IODP) Site U1338 during the Expedition 320/321 Pacific Equatorial Age Transect (PEAT) program contain abundant calcareous nanno- and microfossils. Geochemical proxies from benthic and planktonic foraminiferal and coccolithophore calcite could be very useful at this location; however, good preservation of the calcite is crucial for the proxies to be robust. Here, we evaluate the preservation of specific benthic and planktonic foraminifer species and coccolithophores in fine fraction sediment at Site U1338 using backscattered electron (topography mode) scanning electron microscopy (BSE-TOPO SEM). Both investigated foraminiferal species, Cibicidoides mundulus and Globigerinoides sacculifer, have undergone some alteration. The C. mundulus show minor evidence for dissolution, and only some specimens show evidence of overgrowth. The Gs. sacculifer show definite signs of alteration and exhibit variable preservation, ranging from fair to poor; some specimens show minor overgrowth and internal recrystallization but retain original features such as pores, spine pits, and internal testwall growth structure, whereas in other specimens the recrystallization and overgrowth disguise many of the original features. Secondary electron and BSE-TOPO SEM images show that coccolith calcite preservation is moderate or moderate to poor. Slight to moderate etching has removed central heterococcolith features, and a small amount of secondary overgrowth is also visible. Energy dispersive spectroscopy analyses indicate that the main sedimentary components of the fine fraction sediment are biogenic CaCO3 and SiO2, with some marine barite. Based on the investigations in this data report, geochemical analyses on benthic foraminifers are unlikely to be affected by preservation, although geochemical analyses on the planktonic foraminifers should be treated cautiously because of the fair to poor and highly variable preservation
Formação profissional: exploração sobre o impacto de uma experiência internacional de aprendizagem-serviço de estudantes de terapia ocupacional
International service learning (ISL) acts as a pedagogy that can help health professions students identify the
importance and relevance of providing care based on the principle of social justice. Beyond building entry level
practice skills, health care educators in higher education have a role to ensure that health professions students
have a strong sense of justice and are able to engage in critically conscious practice. Critical consciousness,
identified by Paulo Freire, can aid health professions students in thoughtful and reflective practice founded in
social justice. This study focuses on the implementation of an international service-learning program to teach
occupational therapy students the tenets of social justice. Methods: Two occupational therapy educators
within a Department of Occupational Therapy at a University within the United States conducted a qualitative
analysis of occupational therapy student reflections from a 3-week international service learning experience
in the Dominican Republic. Students were asked to reflect upon their experience and these reflections were
analyzed following qualitative methods for themes. Results: Student reflections reported four themes including
stepping outside my comfort zone, growth, cultural sensitivity, and simplicity and being present. Discussion:
The results of the qualitative analysis of the reflections of the occupational therapy students demonstrates the
powerful impact of international service learning on transforming the beliefs of occupational therapy students
preparing to practice focused on social justice. The results of this study inform educators that international
service learning has the potential to be a powerful pedagogy for teaching occupational therapy students about
social justice.El Aprendizaje-Servicio Internacional (ISL) actúa como una pedagogÃa que ayuda a los profesionales de la
salud a identificar la importancia y pertinencia de prestar una atención basada en el principio de la justicia
social. Más allá de la construcción de competencias básicas a nivel práctico, los educadores tienen un papel
importante para asegurar que los estudiantes de profesiones de la salud tengan un fuerte sentido de la justicia
y sean capaces de participar en una práctica crÃtica y consciente. La conciencia crÃtica, identificada por Paulo
Freire, puede ayudar a los estudiantes en la práctica reflexiva y razonamiento basado en la justicia social.
Este estudio se centra en la implementación de un programa internacional de aprendizaje – servicio para
enseñar a los estudiantes de terapia ocupacional los principios de justicia social. Método: Dos educadores
de terapia ocupacional llevaron a cabo un análisis cualitativo de las reflexiones de los estudiantes de
terapia ocupacional de una experiencia de aprendizaje-servicio internacional de 3 semanas en la República
Dominicana. Se pidió a los estudiantes que reflexionasen sobre sus experiencias y estas reflexiones fueron
analizadas siguiendo métodos cualitativos organizado por ideas centrales. Resultados: las reflexiones de los
estudiantes presentaron cuatro temas esenciales, incluyendo salirse de aquello en lo que los estudiantes se
sienten cómodos, el crecimiento, la sensibilidad cultural, y la sencillez y presencia. Discusión: Los resultados
demuestran el poderoso impacto que tienen el aprendizaje-servicio en la transformación de las creencias
de los estudiantes de terapia ocupacional. Los resultados de este estudio informan a los educadores que el
aprendizaje-servicio internacional tiene el potencial de ser una estrategia pedagógica poderosa para enseñar
a los estudiantes de terapia ocupacional sobre justicia social.O Aprendizagem-Serviço Internacional (ISL) atua como una pedagogia que pode ajudar aos estudantes de
profissões relacionadas com a saúde a identificar a importância e pertinência de prestar uma atenção baseada
no princÃpio da justiça social. Além da construção de competências básicas a nÃvel prático, os educadores de
profissões da saúde na educação superior têm um papel importante para assegurar que os estudantes de
profissões da saúde tenham um forte sentido da justiça e sejam capazes de participar em uma prática crÃtica
e consciente. La consciência crÃtica, identificada por Paulo Freire, pode ajudar aos estudantes de profissões
da saúde na prática reflexiva e raciocÃnio baseado na justiça social. Este estudo se centra na implementação
de um programa internacional de aprendizagem – serviço para ensinar aos estudantes de terapia ocupacional
os princÃpios de justiça social. Métodos: Dois educadores de terapia ocupacional do Departamento de Terapia
Ocupacional de uma Universidade dos Estados Unidos realizaram uma analise qualitativa das reflexões dos
estudantes de terapia ocupacional de uma experiência de aprendizagem-serviço internacional de 3 semanas
na República Dominicana. Pediu-se aos estudantes que refletissem sobre suas experiências e estas reflexões
foram analisadas seguindo métodos qualitativos organizados por ideias centrais. Resultados: as reflexões
dos estudantes apresentaram quatro temas essenciais, incluindo sair daquilo que os estudantes se sentem
cômodos, o crescimento, a sensibilidade cultural, e a simplicidade e presença. Discussão: os resultados da
análise qualitativa das reflexões dos estudantes de terapia ocupacional demonstram o poderoso impacto
que tem o aprendizagem-serviço internacional na transformação das crenças dos estudantes de terapia
ocupacional que se preparam para una prática centrada na justiça social. Os resultados deste estudo informam
aos educadores que o aprendizagem-serviço internacional tem o potencial de ser una estratégia pedagógica
poderosa para educar os estudantes de terapia ocupacional sobre justiça social
prox1b Activity Is Essential in Zebrafish Lymphangiogenesis
BACKGROUND: The lymphatic vascular system, draining interstitial fluids from most tissues and organs, exerts crucial functions in several physiological and pathological processes. Lymphatic system development depends on Prox1, the first marker to be expressed in the endothelial cells of the cardinal vein from where lymph vessels originate. Prox1 ortholog in the optically clear, easily manipulated zebrafish model has been previously isolated and its contribution to lymphangiogenesis has been clarified. Because of a round of genome duplication occurred at the base of teleosts radiation, several zebrafish genes have been retained in duplicate through evolution. We investigated for the presence of additional prox1 genes and determined their role in zebrafish lymphangiogenesis. METHODOLOGY/PRINCIPAL FINDINGS: We isolated a second ortholog, named prox1b, and analyzed its expression during development by whole mount in situ hybridization (WISH). We detected strong prox1b expression in the endothelium of the posterior cardinal vein (PCV) from where lymphatic precursors originate. To analyze prox1b involvement in lymphangiogenesis we utilized the fli1:GFP transgenics and followed the formation of the toracic duct (TD), the primary lymph vessel in fish, after prox1b knockdown. Our findings clearly demonstrated that the absence of prox1b activity severely hampers the formation of the TD. CONCLUSIONS/SIGNIFICANCE: This work provides substantial progress toward the understanding of zebrafish lymphangiogenesis. In light of the features shared by the lymphatic systems of zebrafish and higher vertebrates, the establishment of such lymphatic model will provide a powerful tool to study, for instance, disorders of body fluid homeostasis, inflammation and cancer metastasis, and may ultimately contribute to novel therapies
On Passing the Buck
Imagine there are n\u3e1 people seated around a table, and person S starts with a fair coin they will flip to decide whom to hand the coin next -- if heads they pass right, and if tails they pass left. This process continues until all people at the table have touched the coin. Curiously, it turns out that all people seated at the table other than S have the same probability 1/(n-1) of being last to touch the coin. In fact, Lovasz and Winkler ( A note on the last new vertex visited by a random walk, J. Graph Theory, Vol. 17 Iss. 5 (1993), 593-596) showed that this situation and the one where a person is permitted to pass the coin to anyone else with uniform probability 1/(n-1) are the only scenarios where everyone at the table other than S have the same probability 1/(n-1) of touching the coin last. This begs the question -- what is the probability that a person will touch the coin last in scenarios that lie outside these two? We consider a version where the table has two sides, and the passing rule involves handing the coin to someone on the opposite side of the table with uniform probability. What is the resulting probability that a particular person touches the coin last in this two-sided situation
Implementation of repeat HIV testing during pregnancy in Kenya: a qualitative study.
BackgroundRepeat HIV testing in late pregnancy has the potential to decrease rates of mother-to-child transmission of HIV by identifying mothers who seroconvert after having tested negative for HIV in early pregnancy. Despite being national policy in Kenya, the available data suggest that implementation rates are low.MethodsWe conducted 20 in-depth semi-structured interviews with healthcare providers and managers to explore barriers and enablers to implementation of repeat HIV testing guidelines for pregnant women. Participants were from the Nyanza region of Kenya and were purposively selected to provide variation in socio-demographics and job characteristics. Interview transcripts were coded and analyzed in Dedoose software using a thematic analysis approach. Four themes were identified a priori using Ferlie and Shortell's Framework for Change and additional themes were allowed to emerge from the data.ResultsParticipants identified barriers and enablers at the client, provider, facility, and health system levels. Key barriers at the client level from the perspective of providers included late initial presentation to antenatal care and low proportions of women completing the recommended four antenatal visits. Barriers to offering repeat HIV testing for providers included heavy workloads, time limitations, and failing to remember to check for retest eligibility. At the facility level, inconsistent volume of clients and lack of space required for confidential HIV retesting were cited as barriers. Finally, at the health system level, there were challenges relating to the HIV test kit supply chain and the design of nationally standardized antenatal patient registers. Enablers to improving the implementation of repeat HIV testing included client dissemination of the benefits of antenatal care through word-of-mouth, provider cooperation and task shifting, and it was suggested that use of an electronic health record system could provide automatic reminders for retest eligibility.ConclusionsThis study highlights some important barriers to improving HIV retesting rates among pregnant women who attend antenatal clinics in the Nyanza region of Kenya at the client, provider, facility, and health system levels. To successfully implement Kenya's national repeat HIV testing guidelines during pregnancy, it is essential that these barriers be addressed and enablers capitalized on through a multi-faceted intervention program
Introduction: The Work, or the Agency, of the Nonhuman in Premodern Art
An overview of the "state of the field" of critical posthumanist studies that also argues for the important intervention of premodern studies into contemporary critical posthumanism studies, and which serves as the Introduction (with chapter summaries) to "Fragments for a History of a Vanishing Humanism," eds. Myra Seaman and Eileen A. Joy (Ohio State University Press, 2016)
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