Theoretical investigation of liquid water injection into the shock layer of a reentry vehicle

Mathematical model for flow field of liquid spray injected into supersonic air streaming past blunt bod

Interview with Dave Dellinger

In his February 1994 interviews with Ron Chepesiuk, Dave Dellinger revealed his view of his involvement during the anti-war movement. Dellinger was a non-violence activist and a leader of the anti-war movement of the 1960s. Dellinger discussed topics such as the sixties counterculture, Ho Chi Minh and their friendship, non-violence, self-esteem, drugs, the Chicago 7, Abbie Hoffman, and the legacy of the 1960s. Dellinger also discussed his views of activism of the 1990s, his view of the Clinton administration, the U.S. government and military, violence vs. non-violence, and the impact of the end of the Cold War on the anti-war movement. This interview was conducted for inclusion into the Louise Pettus Archives and Special Collections Oral History Program.https://digitalcommons.winthrop.edu/oralhistoryprogram/1066/thumbnail.jp

Estimating diet composition from scat analysis in otariid seals (Otariidae): is it reliable?

Analysis of teleost sagittal otoliths contained in scats has been widely used to determine the diet of seals. This method is based on the assumption that relative frequencies of otoliths in scats faithfully reflect those of fish in the diet. This assumption has rarely been tested experimentally. We compared the ratios of herring (Clupea harengus) to sprat (Sprattus sprattus) oto liths in faeces (output) of captive California sea lions (Zalophus calijornianus) and South American fur seals (Arctocephalus australis) with the ratios at feeding (input). Sea lions and fur seals showed no consistent differences in recovery rates and partial digestion of otoliths. Output ratios deviated only slightly from input ratios, the smaller sprat otoliths being underrepre sented in the output by 8%. Only about 40% of the otoliths fed to the seals were found in the scats. For both species partial digestion of otoliths led to a 16% underestimation of fish length and a 35% underestimation of fish mass.L'analyse des otolithes de tClCostCens contenus dans les fkces est une mCthode trks rCpandue de dktermination du rCgime alimentaire des phoques. Cette mCthode suppose que les frCquences relatives d'otolithes dans les fkces reflktent fidklement les frkquences relatives des poissons dans le rCgime. Cette prCmisse n'a pratiquement jamais fait l'objet de ~Crifications expkrimentales. Nous avons mesurC la proportion d'otolithes de harengs (Clupea harengus) et celle d'otolithes de sprats (Sprattus sprattus) dans les fkces (sortie) de Lions de mer californiens, Zalophus calijiornianus, et d'otaries a fourrure sud amkricaines, Arctocephalus australis, gardCs en captivitC, et comparC ces mesures aux proportions d'otolithes ingCrCs (entrCe). I1 n'y avait pas de diffkrence constante entre lions de mer et otaries et les taux de rCcupCration et de digestion partielle d'otolithes Ctaient les memes chez les deux espkces. Les proportions a la sortie diffkraient seulement un peu des proportions a I'entrCe et les otolithes des sprats, plus petits, Ctaient sous-reprCsentCs de 8% a la sortie. Seulement 40% environ des oto lithes ingCrCs ont CtC retrouvks a la sortie. La digestion partielle des otolithes chez les deux espkces entraine une sous-estima tion de la longueur des poissons consommCs, de I'ordre de 16%, et de la masse des poissons consommCs, de l'ordre de 35%.info:eu-repo/semantics/publishedVersio

Phosphorylation of Akt and ERK1/2 Is Required for VEGF-A/VEGFR2-Induced Proliferation and Migration of Lymphatic Endothelium

There is growing evidence that vascular endothelial growth factor-A (VEGF-A), a ligand of the receptor tyrosine kinases VEGFR1 and VEGFR2, promotes lymphangiogenesis. However, the underlying mechanisms by which VEGF-A induces the growth of lymphatic vessels remain poorly defined. Here we report that VEGFR2, not VEGFR1, is the primary receptor regulating VEGF-A-induced lymphangiogenesis. We show that specific inhibition of VEGF-A/VEGFR2 signaling with the fully human monoclonal antibody r84 significantly inhibits lymphangiogenesis in MDA-MB-231 tumors. In vitro experiments with primary human dermal lymphatic endothelial cells (LECs) demonstrate that blocking VEGF-A activation of VEGFR2, not VEGFR1, significantly inhibits VEGF-A-induced proliferation and migration of LECs. We show that VEGF-A stimulation of LECs leads to the phosphorylation of VEGFR2 (Tyr 951, 1054, 1059, 1175, and 1214) which subsequently triggers PKC dependent phosphorylation of ERK1/2 and PI3-K dependent phosphorylation of Akt. Additionally, we demonstrate that inhibitors that suppress the phosphorylation of ERK1/2 and Akt significantly block VEGF-A- induced proliferation and migration of LECs. Together, these results shed light on the mechanisms regulating VEGF-A-induced proliferation and migration of LECs, reveal that VEGFR2 is the primary signaling VEGF-A receptor on lymphatic endothelium, and suggest that therapeutic agents targeting the VEGF-A/VEGFR2 axis could be useful in blocking the pathological formation of lymphatic vessels

Foraging behavior of juvenile loggerhead sea turtles in the open ocean: from Lévy exploration to area-restricted search

Most sea turtle species spend part of, or their entire juvenile stage in pelagic habitats. A key question is how pelagic turtles exploit their environment to optimize prey intake and max imize fitness. This study combined animal telemetry with remote-sensed environmental data to quantify the drivers and patterns of foraging behavior of juvenile loggerhead sea turtles in the pelagic eastern North Atlantic. Juveniles ranged in size from 34 to 58 cm straight carapace length. First-passage time (FPT) analysis, used to quantify search effort, indicated that turtles performed area-restricted searches at nested spatial scales of 10 and 50 to 200 km. High-usage areas, as quantified by FPT, were associated with increased dive activity and weak surface currents, as well as with oceanographic features (high chlorophyll a and shallower bathymetry) thought to stimu late prey availability. Conversely, low-usage areas (i.e. transit areas) were associated with deep, probably exploratory dives, typical from Lévy movement patterns. Further interpretation of dive data indicates greater dive activity in shallow depths (0 to 10 m) during the night and during tran sit. Conversely, greater activity at intermediate depths (10 to 50 m) was observed during daytime, under strong lunar illumination and in high-usage areas, suggesting these depths are major day time foraging layers. This study clarifies the foraging ecology of sea turtles during their develop ment phase in the open sea, providing evidence that these pelagic predators can adjust their for aging strategies and effort in response to the local conditions of their dynamic environment.info:eu-repo/semantics/publishedVersio

Understanding student learning pathways in traditional online history courses: utilizing process mining analysis on clickstream data

Purpose This study explores ongoing research into self-mapped learning pathways that students utilize to move through a course when given two modalities to choose from: one that is instructor-led and one that is student-directed. Design/methodology/approach Process mining analysis was utilized to examine and cluster clickstream data from an online college-level History course designed with dual modality choices. This paper examines some of the results from different approaches to clustering the available data. Findings By examining how often students interacted with others, whether they were more internal or external facing with their pathway choices, and whether or not they completed a learning pathway, this study identified five general tactics from the data: Individualistic Internal; Non-completing Internal; Completing, Interactive Internal; Completing, Interactive, and Reflective and Completing External. Further analysis of when students used each tactic led to the identification of four different strategies that learners utilized during class sessions. Practical implications The results of this analysis could potentially lead to the creation of customizable design models that can assist learners as they navigate modality choices in learner-centered or less-structured learning design methodologies. Originality/value Few courses are designed to give the learners the options to follow the instructor or create their own learning pathway. Knowing how to identify what choices a learner might take in these scenarios is even less explored. Preliminary data for this paper was originally presented as a poster session at the Learning Analytics and Knowledge conference in 2019

Gill monogeneans of the chub mackerel, Scomber japonicus from Madeiran waters of the Atlantic Ocean, Portugal

Five species of monogeneans were recovered from the gill filaments of 181 chub mackerel, Scomber japonicus, from the Madeiran waters of the Atlantic Ocean, Portugal, during 2004/2005. The monogenean Pseudokuhnia minor showed the highest prevalence (98.68%) and a mean intensity of 28.23, followed by Kuhnia scombri (prevalence of 43.71% and mean intensity of 2.69) and K. scombercolias (prevalence of 39.1% and a mean intensity of 1.81). Kuhnia sprostonae and Grubea cochlear were rare, occurring in only one and five fish hosts respectively. No correlation between fish host length and mean intensity of infection with the three most abundant monogeneans was found. However, significant differences in prevalence and abundance were found in relation to date of sampling for P. minor, and all parasites were aggregated in their distribution.info:eu-repo/semantics/publishedVersio

Technical note: in situ measurement of flux and isotopic composition of CO2 released during oxidative weathering of sedimentary rocks

Oxidative weathering of sedimentary rocks can release carbon dioxide (CO2) to the atmosphere and is an important natural CO2 emission. Two mechanisms operate – the oxidation of sedimentary organic matter and the dissolution of carbonate minerals by sulfuric acid. It has proved difficult to directly measure the rates at which CO2 is emitted in response to these weathering processes in the field, with previous work generally using methods which track the dissolved products of these reactions in rivers. Here we design a chamber method to measure CO2 production during the oxidative weathering of shale bedrock, which can be applied in erosive environments where rocks are exposed frequently to the atmosphere. The chamber is drilled directly into the rock face and has a high surface-area-to-volume ratio which benefits measurement of CO2 fluxes. It is a relatively low-cost method and provides a long-lived chamber (several months or more). To partition the measured CO2 fluxes and the source of CO2, we use zeolite molecular sieves to trap CO2 actively (over several hours) or passively (over a period of months). The approaches produce comparable results, with the trapped CO2 having a radiocarbon activity (fraction modern, Fm) ranging from Fm = 0.05 to Fm = 0.06 and demonstrating relatively little contamination from local atmospheric CO2 (Fm = 1.01). We use stable carbon isotopes of the trapped CO2 to partition between an organic and inorganic carbon source. The measured fluxes of rock-derived organic matter oxidation (171±5mgCm−2day−1) and carbonate dissolution by sulfuric acid (534±16mgCm−2day−1) from a single chamber were high when compared to the annual flux estimates derived from using dissolved river chemistry in rivers around the world. The high oxidative weathering fluxes are consistent with the high erosion rate of the study region. We propose that our in situ method has the potential to be more widely deployed to directly measure CO2 fluxes during the oxidative weathering of sedimentary rocks, allowing for the spatial and temporal variability in these fluxes to be determined