3,836 research outputs found

    Changes in lipophorins are related to the activation of phenoloxidase in the haemolymph of Locusta migratoria in response to injection of immunogens

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    In Locusta migratoria, activation of phenoloxidase in the haemolymph in response to injection of laminarin is age-dependent: being absent in fifth instar nymphs and newly emerged adults, and only becoming evident four days after the final moult. This pattern of change in phenoloxidase activation correlates with the pattern of change in the concentration of apolipophorin-III (apoLp-III) in the haemolymph. Injection of a conspecific adipokinetic hormone (Lom-AKH-I) has no effect on the phenoloxidase response in nymphs or newly emerged adults but, in adults older than four days, co-injection of the hormone with laminarin prolongs the activation of phenoloxidase in the haemolymph: a similar enhancement of the response to laminarin is observed in locusts that have been starved for 48 h but not injected with AKH-I. During most of the fifth stadium, injection of laminarin results in a decrease in the level of prophenoloxidase in the haemolymph; an effect that is not observed in adults of any age. Marked changes in the concentration of apoLp-III, and the formation of LDLp in the haemolymph, are observed after injection of laminarin (or LPS) and these are remarkably similar, at least qualitatively, to those that occur after injection of AKH-I. The involvement of lipophorins in the activation of locust prophenoloxidase in response to immunogens is discussed

    Modeling Course-Based Undergraduate Research Experiences: An Agenda for Future Research and Evaluation

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    Course-based undergraduate research experiences (CUREs) are being championed as scalable ways of involving undergraduates in science research. Studies of CUREs have shown that participating students achieve many of the same outcomes as students who complete research internships. However, CUREs vary widely in their design and implementation, and aspects of CUREs that are necessary and sufficient to achieve desired student outcomes have not been elucidated. To guide future research aimed at understanding the causal mechanisms underlying CURE efficacy, we used a systems approach to generate pathway models representing hypotheses of how CURE outcomes are achieved. We started by reviewing studies of CUREs and research internships to generate a comprehensive set of outcomes of research experiences, determining the level of evidence supporting each outcome. We then used this body of research and drew from learning theory to hypothesize connections between what students do during CUREs and the outcomes that have the best empirical support. We offer these models as hypotheses for the CURE community to test, revise, elaborate, or refute. We also cite instruments that are ready to use in CURE assessment and note gaps for which instruments need to be developed.Howard Hughes Medical InstituteScience and Mathematics Educatio

    Interactions between the endocrine and immune systems in locusts

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    The prophenoloxidase cascade in the haemolymph of mature adult Locusta migratoria migratorioides (R & F) is activated in response to injection of laminarin, a -1,3 glucan. Co-injection of adipokinetic hormone-I (Lom-AKH-I) and laminarin prolongs the activation of the enzyme in a dose-dependent manner. However, injections of bacterial lipopolysaccharide (LPS) do not activate prophenoloxidase unless AKH is co-injected, when there is a dose-dependent increase in the level of phenoloxidase that persists in the haemolymph for several hours. Even when AKH is co-injected, the highest levels of phenoloxidase activity are always greater after injection of laminarin than after LPS, and these two immunogens must activate the prophenoloxidase cascade by quite distinct pathways. In the present study, interactions between the endocrine and immune systems were examined with respect to activation of prophenoloxidase and the formation of nodules: injection of LPS induces nodule formation in adult locusts. With LPS from Pseudomonas aeruginosa, nodules form exclusively in dense accumulations in the anterior portion of the abdomen on either side of the dorsal blood vessel associated with the dorsal diaphragm. However, with LPS from Escherichia coli, fewer nodules are formed but with a similar distribution, except that occasionally some nodules are aligned additionally on either side of the ventral nerve cord. Co-injection of Lom-AKH-I with LPS from either bacteria stimulates greater numbers of nodules to be formed. This effect of coinjection of AKH on nodule formation is seen at low doses of hormone with only 0.3 or 0.4 pmol of Lom-AKH-1, respectively, increasing the number of nodules by 50%. Injections of octopamine or 5-hydroxytryptamine do not mimic either of the actions of Lom-AKH-I described here. Co-injection of an angiotensin-converting enzyme inhibitor, captopril, reduces nodule formation in response to injections of LPS but has no effect on the activation of phenoloxidase. Co-injection of an inhibitor of eicosanoid synthesis, dexamethasone, with LPS influences nodule formation (with or without AKH) in different ways according to the dose of dexamethasone used, but does not affect activation of prophenoloxidase. Eicosanoid synthesis is important for nodule formation, but not for the activation of the prophenoloxidase cascade in locust haemolymph

    Experimental Design for the Gemini Planet Imager

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    The Gemini Planet Imager (GPI) is a high performance adaptive optics system being designed and built for the Gemini Observatory. GPI is optimized for high contrast imaging, combining precise and accurate wavefront control, diffraction suppression, and a speckle-suppressing science camera with integral field and polarimetry capabilities. The primary science goal for GPI is the direct detection and characterization of young, Jovian-mass exoplanets. For plausible assumptions about the distribution of gas giant properties at large semi-major axes, GPI will be capable of detecting more than 10% of gas giants more massive than 0.5 M_J around stars younger than 100 Myr and nearer than 75 parsecs. For systems younger than 1 Gyr, gas giants more massive than 8 M_J and with semi-major axes greater than 15 AU are detected with completeness greater than 50%. A survey targeting young stars in the solar neighborhood will help determine the formation mechanism of gas giant planets by studying them at ages where planet brightness depends upon formation mechanism. Such a survey will also be sensitive to planets at semi-major axes comparable to the gas giants in our own solar system. In the simple, and idealized, situation in which planets formed by either the "hot-start" model of Burrows et al. (2003) or the core accretion model of Marley et al. (2007), a few tens of detected planets are sufficient to distinguish how planets form.Comment: 15 pages, 9 figures, revised after referee's comments and resubmitted to PAS

    Optimum take-off angle in the long jump

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    In this study, we found that the optimum take-off angle for a long jumper may be predicted by combining the equation for the range of a projectile in free flight with the measured relations between take-off speed, take-off height and take-off angle for the athlete. The prediction method was evaluated using video measurements of three experienced male long jumpers who performed maximum-effort jumps over a wide range of take-off angles. To produce low take-off angles the athletes used a long and fast run-up, whereas higher take-off angles were produced using a progressively shorter and slower run-up. For all three athletes, the take-off speed decreased and the take-off height increased as the athlete jumped with a higher take-off angle. The calculated optimum take-off angles were in good agreement with the athletes' competition take-off angles

    Being a Feminist Community During a Pandemic: Our Editors’ Welcome

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    Volume 4, the pandemic issue of The Seneca Falls Dialogues Journal, features a selection of participants from our 2020 gathering who have transformed their conference offerings into articles for posterity, ones that aim to keep the dialogue going and widen the sphere of feminist inquiry

    The Seneca Falls Dialogues Journal, v. 4, 2021 (complete issue)

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    Table of Contents Being a Feminist Community During a Pandemic: Our Editors’ Welcome by Jill Swiencicki, Lisa Cunningham, & Mary E. Graham Creating Seneca Falls Dialogues Journal by Deborah Uman & Barbara LeSavoy Disrupters: Three Women of Color Tell Their Stories by Dulce María Gray, Denise A. Harrison, & Yuko Kurahashi Contemporary Black Women’s Voting Rights Activism: Some Historical Perspective by Alison Parker, Valeria Sinclair-Chapman, & Naomi R. Williams Shapeshifting Power: Indigenous Teachings of Trickster Consciousness and Relational Accountability for Building Communities of Care by Ionah M. Elaine Scully Influencing Public Opinion: Public Relations and the Arrest of Susan B. Anthony by Arien Rozelle #THEMTOO: Two NFL Team Options for Not Exploiting Women Cheerleaders by Melanie Kelly, Colby A. Murphy, & Mary E. Graham Feminist Attitudes, Behaviors, and Culture Shaping Women’s Center Practice by Angela Clark-Taylor, Emily Creamer, Barbara LeSavoy, & Catherine Cerull

    HIV-related sexual risk behaviour between 1996 and 2008, according to age, among men who have sex with men (Scotland)

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    Objective: To examine changes in the proportions of those reporting 2+ unprotected anal intercourse (UAI) partners in the previous 12 months among men who have sex with men (MSM) in Scotland between 1996 and 2008. Differences according to age group were also examined. Methods: Logistic regression was used with data from eight cross-sectional anonymous, self-report surveys in commercial gay venues in Glasgow and Edinburgh (N=10 223). Data were stratified according to survey and age group (<25 years vs ≥25 years). Results: The percentage of 2+ UAI partners reported in the previous 12 months increased significantly between 2000 and 2002, adjusted for age group. When the surveys were divided into two time periods (1996-2000 and 2002-2008), no significant differences were found within each time period in the percentage of 2+ UAI partners reported (adjusted for age group). However, a significant increase was found when the aggregated figures for 2002-2008 were compared with those for 1996-2000. At the aggregate level, those aged <25 years were significantly more likely than those aged ≥25 years to report 2+ UAI partners in the previous 12 months (adjusted for survey). Conclusions: HIV-related sexual risk behaviour did not change significantly between 2002 and 2008 among MSM in Scotland, after the increases noted between 2000 and 2002. A significant minority of MSM continue to engage in relatively high levels of sexual risk, and younger generations appear to be at particular risk. This represents a public health concern and highlights the need for targeted age-specific interventions

    Constraints on the Progenitor System of the Type Ia Supernova 2014J from Pre-Explosion Hubble Space Telescope Imaging

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    We constrain the properties of the progenitor system of the highly reddened Type Ia supernova (SN) 2014J in Messier 82 (M82; d ~ 3.5 Mpc). We determine the SN location using Keck-II K-band adaptive optics images, and we find no evidence for flux from a progenitor system in pre-explosion near-ultraviolet through near-infrared Hubble Space Telescope (HST) images. Our upper limits exclude systems having a bright red giant companion, including symbiotic novae with luminosities comparable to that of RS Ophiuchi. While the flux constraints are also inconsistent with predictions for comparatively cool He-donor systems (T < ~35,000 K), we cannot preclude a system similar to V445 Puppis. The progenitor constraints are robust across a wide range of R_V and A_V values, but significantly greater values than those inferred from the SN light curve and spectrum would yield proportionally brighter luminosity limits. The comparatively faint flux expected from a binary progenitor system consisting of white dwarf stars would not have been detected in the pre-explosion HST imaging. Infrared HST exposures yield more stringent constraints on the luminosities of very cool (T < 3000 K) companion stars than was possible in the case of SN Ia 2011fe.Comment: Accepted by ApJ 14 May 2014 with only minor revision
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