225 research outputs found

    Measurement of hydroxyl temperatures in the upper atmosphere with a high sensitivity spectrometer

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    The hydroxyl temperatures in the upper atmosphere were measured over a five-week period in January and February of 1975 and 1976 in order to determine the variation of the rotational temperatures of OH with stratospheric warming events occurring over the New England area. The OH temperatures were also recorded during the summer of 1975 in the Fairfield, Connecticut area. Data show a wide fluctuation in temperatures amounting to as much as a couple of hundred degrees in the course of an evening. A modified Ebert-Fastie spectrometer with a focal length of 1 meter was used to examined the vibration-rotation bands of atmospheric OH in the 7000 to 9000 range. This wavelength was searched and the strongest signal was obtained from the 6-2 band (band head at 8280 A). Graphs show the 6-2 band of the Meinel OH spectrum, the real time and average spectra for the 6-2 band of OH, and rotational temperature of OH vs time for two evenings

    The origins of spectra, an organization for LGBT mathematicians

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    Shining a light on a hidden figure: Dorothy hoover

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    An Effective Version of Belyi\u27s Theorem

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    We compute bounds on covering maps that arise in Belyi\u27s Theorem. In particular, we construct a library of height properties and then apply it to algorithms that produce Belyi maps. Such maps are used to give coverings from algebraic curves to the projective line ramified over at most three points. The computations here give upper bounds on the degree and coefficients of polynomials and rational functions over the rationals that send a given set of algebraic numbers to the set {0,1,∞} with the additional property that the only critical values are also contained in {0,1,∞}

    Impulse balance and framing effects in threshold public good games

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    In this paper, we revisit the evidence for framing effects in threshold public good games. Our particular focus is on why the probability of providing the public good appears to be higher in positive, give frames compared with negative, take frames. We show that the impulse balance theory can explain this effect. We also report a new experiment designed to test the predictions of the impulse balance theory. The results of the experiment fit well, both in quantitative and qualitative terms, with our predictions.</p

    Macrophage inflammatory protein-1alpha mediates matrix metalloproteinase-9 enhancement in human adherent monocytes fed with malarial pigment.

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    Abstract Objective To investigate the role of macrophage inflammatory protein-1alpha (MIP-1alpha) in the detrimental enhancement of matrix metalloproteinase-9 (MMP-9) expression, release and activity induced by phagocytosis of malarial pigment (haemozoin, HZ) in human monocytes. Methods Human adherent monocytes were unfed/fed with native HZ for 2 h. After 24 hours, MIP-1alpha production was evaluated by ELISA in cell supernatants. Alternatively, HZ-unfed/fed monocytes were treated in presence/absence of anti-human MIP-1alpha blocking antibodies or recombinant human MIP-1alpha for 15 h (RNA studies) or 24 h (protein studies); therefore, MMP-9 mRNA expression was evaluated in cell lysates by Real Time RT-PCR, whereas proMMP-9 and active MMP-9 protein release were measured in cell supernatants by Western blotting and gelatin zymography. Results Phagocytosis of HZ by human monocytes increased production of MIP-1 alpha, mRNA expression of MMP-9 and protein release of proMMP-9 and active MMP-9. All the HZ-enhancing effects on MMP-9 were abrogated by anti-human MIP-1alpha blocking antibodies and mimicked by recombinant human MIP-1alpha. Conclusions The present work suggests a role for MIP-1alpha in the HZ-dependent enhancement of MMP-9 expression, release and activity observed in human monocytes, highlighting new detrimental effects of HZ-triggered proinflammatory response by phagocytic cells in falciparum malaria

    Haemozoin Induces Early Cytokine-Mediated Lysozyme Release from Human Monocytes through p38 MAPK- and NF-kappaB- Dependent Mechanisms

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    Malarial pigment (natural haemozoin, HZ) is a ferriprotoporphyrin IX crystal produced by Plasmodium parasites after haemoglobin catabolism. HZ-fed human monocytes are functionally compromised, releasing increased amounts of pro-inflammatory molecules, including cytokines, chemokines and cytokine-related proteolytic enzyme Matrix Metalloproteinase-9 (MMP-9), whose role in complicated malaria has been recently suggested. In a previous work HZ was shown to induce through TNFalpha production the release of monocytic lysozyme, an enzyme stored in gelatinase granules with MMP-9. Here, the underlying mechanisms were investigated. Results showed that HZ lipid moiety promoted early but not late lysozyme release. HZ-dependent lysozyme induction was abrogated by anti-TNFalpha/IL-1 beta/MIP-1 alpha blocking antibodies and mimicked by recombinant cytokines. Moreover, HZ early activated either p38 MAPK or NF-kappaB pathways by inducing: p38 MAPK phosphorylation; cytosolic I-kappaB alpha phosphorylation and degradation; NF-kappaB nuclear translocation and DNA-binding. Inhibition of both routes through selected molecules (SB203580, quercetin, artemisinin, parthenolide) prevented HZ-dependent lysozyme release. These data suggest that HZ-triggered overproduction of TNFalpha, IL-1 beta and MIP-1 alpha mediates induction of lysozyme release from human monocytes through activation of p38 MAPK and NF-kappaB pathways, providing new evidence on mechanisms underlying the HZ-enhanced monocyte degranulation in falciparum malaria and the potential role for lysozyme as a new affordable marker in severe malaria

    Compliance externalities and the role model effect on law abidance : field and survey-experimental evidence

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    Recent theories of compliance predict that, apart from utilitarian considerations, individual decisions to respect or break the law account for virtuous motives and nonutilitarian willingness to promote the social good. We test whether empirical evidence supports these theories by collecting data on cyclists' decisions to ignore a red traffic light in a natural setting. We consider different situations where noncompliance is costly, but without risk, and where material deterrence incentives from legal sanctions remain constant. The only difference between the situations lies in who is observing the cyclists' decision at the traffic light at the intersection of a footpath with the cycle track. We find that about 68 percent of cyclists ignore the red traffic light when there is the opportunity to do so. This frequency does not change substantially when adult bystanders are observing at the pedestrian traffic light. Interestingly, the violation frequency drops to about 10 percent when children are present. Robustness checks rule out the alternative explanations that this change is driven by concerns for children's unpredictable actions, or by the simultaneous presence of other adult bystanders. In a vignette study, we additionally dissect the cyclists' motives for being compliant. Results suggest a “role‐model effect” on compliance. When asked, the majority of participants report that the willingness to educate and be a good example is the most important reason for their decision to abide by the law, hence supporting the empirical observation that promoting the social good can be an important nonutilitarian motive of compliance decisions

    Malarial pigment enhances heat shock protein-27 in THP-1 cells: New perspectives for in vitro studies on monocyte apoptosis prevention

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    Abstract Objective To investigate the effect of malarial pigment (hemozoin, HZ) on expression of heat shock proteins (HSPs) and cell viability in human monocytes by using a stable cell line (THP-1 cells). Methods THP-1 cells were fed with native HZ or treated with pro-apoptotic molecule gliotoxin for 9 h. Thereafter, the protein expression of HSP-27 and HSP-70 was evaluated by western blotting. Alternatively, HZ-fed cells were cultured up to 72 h and cell viability parameters (survival, apoptosis and necrosis rates) were measured by flow cytometric analysis. Results HZ increased basal protein levels of HSP-27 without altering those of HSP-70 in THP-1 cells, and promoted long-term cell survival without inducing apoptosis. As expected, gliotoxin inhibited HSP-27 protein expression and promoted long-term cell apoptosis. Conclusions Present data show that HZ prevents cell apoptosis and enhances the expression of anti-apoptotic HSP-27 in THP-1 cells, confirming the previous evidences obtained from HZ-fed immunopurified monocytes. Since the use of a stable cell line is pivotal to perform HSP-27 silencing experiments, monocytic THP-1 cells could be a good candidate line for such an approach, which is heavily required to clarify the role of HSP-27 in survival of impaired HZ-fed monocytes during falciparum malaria
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