2,866 research outputs found

    Targeted delivery of platinum-based anticancer complexes

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    The most widely used anticancer drugs are platinum-based. Their efficacy might be improved by carriers which can transport large numbers of Pt centres, shield the drug from premature activation, and/or deliver Pt specifically to cancer cells using vectors which recognise specific targets. We describe recent progress using functionalized carbon nanotubes (CNTs) and nanorods, hollow Prussian blue (HPB), magnetic iron oxide and gold nanoparticles, liposomes, nanogels and polymers, as well as active targeting by conjugation to biodegradable proteins and peptides (e.g. EGF, heparin, herceptin, somatostatin and TAT). Spatially targeted activation of PtIV prodrugs using light is also a promising approach. Interestingly, use of these new delivery and targeting systems for platinum drugs can lead to species with unusual reactivity which can kill cancer cells by new mechanisms

    Habitat-Based Intraguild Predation By Caribbean Reef Octopus Octopus Briareus on Juvenile Caribbean Spiny Lobster Panulirus Argus

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    Intraguild predation occurs when species simultaneously compete for resources and interact as predator and prey, which describes the interaction between juvenile Caribbean spiny lobster Panulirus argus and Caribbean reef octopus Octopus briareus in the Florida Keys, USA. Octopuses are notorious predators of decapod crustaceans, and their use of crevice shelters suggests that they may also compete for shelter with their lobster prey. Lobsters use mainly chemical cues to detect and avoid octopus, so we hypothesized that the negative association between these species may be as much the consequence of avoidance of a superior competitor as it is of direct predation. Surveys of lobsters and octopuses occupying artificial shelters at 19 hard-bottom sites confirmed that lobsters do not share dens with octopuses, and also show that lobster and octopus abundances are negatively correlated. Tethering experiments on a subset of those sites revealed that predation on lobster was indeed higher on sites with more octopuses. Results from mesocosm studies indicated that although juvenile lobsters do not attain a size refuge from octopus predation, the presence of alternative prey and lobster conspecifics reduces the risk of predation on lobster by octopus. Mesocosm experiments also showed that octopuses were the competitive dominants when shelter was limited. Thus, the negative association between lobster and octopus in the field appears to be driven by both predation and avoidance of octopus-rich sites by lobsters, rather than competition per se. However, crevice shelters suitable for juvenile lobster are limited in many hard-bottom areas in the Florida Keys, so areas where octopuses are abundant may further limit the local accessibility of shelters for juvenile spiny lobsters even if the direct effects of predation by octopus are minimal

    A 4-Planet System Orbiting the K0V Star HD 141399

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    We present precision radial velocity (RV) data sets from Keck-HIRES and from Lick Observatory's new Automated Planet Finder Telescope and Levy Spectrometer on Mt. Hamilton that reveal a multiple-planet system orbiting the nearby, slightly evolved, K-type star HD 141399. Our 91 observations over 10.5 years suggest the presence of four planets with orbital periods of 94.35, 202.08, 1070.35, and 3717.35 days and minimum masses of 0.46, 1.36, 1.22, and 0.69 Jupiter masses respectively. The orbital eccentricities of the three inner planets are small, and the phase curves are well sampled. The inner two planets lie just outside the 2:1 resonance, suggesting that the system may have experienced dissipative evolution during the protoplanetary disk phase. The fourth companion is a Jupiter-like planet with a Jupiter-like orbital period. Its orbital eccentricity is consistent with zero, but more data will be required for an accurate eccentricity determination.Comment: 11 pages, 13 figures, To appear in the Astrophysical Journa

    Radiocarbon Isotopic Classification of Deep Tropical Forest Soils

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    Tropical forest soils have an important role in global carbon (C) stocks. Small changes in the cycling of C could drastically affect atmospheric carbon dioxide (CO2) concentrations and active cycling of carbon in a forest community. Currently, little is understood of how tropical forest soils will respond to the increasing global temperatures. To examine the effects of warming/ drought on losses of older versus younger soil C pools, we implemented radiocarbon (14C) isotopic characterization of various soil plot samples and depths from the Luquillo Experimental Forest, Puerto Rico. 14C was measured using Accelerated Mass Spectrometry (AMS) from catalytically condensed carbon in order to examine the initial carbon stocks of the test plots. This examination was done in order to determine the age of the carbon in the soil plots before implementation of a long term warming experiment. In addition to determining the age of the soil C, the samples were submitted to a Density Fractionation Process to obtain varying aggregate fractions. These were also submitted to AMS for mean residence time of the C stocks. The soil 14C was significantly different in the Heavy and Free Light density fractions. This implies that the soil C turnover increases as you near the top depth of the soil pit samples. The results will be used to establish the initial composition of the sample soils for a warming experiment that will model future changes in climate

    The anti-civic effects of popular culture on American teenagers

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    Civic participation and civic awareness is essential to the maintenance of American democracy. Strong civic communities serve to promote prosperity, ensure the resolution of collective problems, and act as a check upon the power of the state. But in 2002, there is little doubt that, across a wide range of indicators, America’s civic culture is in decline. Voting rates have fallen rapidly over the past several decades, and so too has trust in government. Equally troubling Ec002 Massachusetts Department of Education [email protected] Massachusetts Department of Education Massachusetts Department of Education Massachusetts Department of Education [email protected] Anders Lewis Jennifer Butler Melanie Winklosky Sandra Stotsky ESE Nº002 2002 is the disconcerting dearth of civic knowledge among American youths and the drop in participation, among all Americans, in numerous civic organizations, from church-affiliated groups to voluntary and fraternal organizations as well as women’s auxiliaries and unions. There are many causes for these trends. This paper examines how popular culture affects civic participation and civic awareness among a group of particularly active teenagers in Massachusetts. We found that popular culture has a generally negative influence on civic life but that its effects are not one-sided and that it can be mitigated by strong families and quality schools committed to an academic and civic education

    Factors contributing to viewing automobile commuting as a waste of time

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    Many commuters view their commute as a waste of time. Although there is an ample amount of research on commuting, there is limited research on what negatively impacts the commuting experience. The current study sought to evaluate the relationship between commuters and their everyday commute. The following factors (i.e., gender identity, age, length, unpredictability, delays, time pressures, and congestion) were evaluated to predict seeing one’s commute as a waste of time. We hypothesized that men and younger commuters, as well as those who were unsatisfied with the length, unpredictability, delays, time pressures, and congestion during the commute, would find their commutes more of a waste of time. We also predicted that those who used their commute productively would not see it as a waste of time. For this study, 490 participants took an online survey. Using hierarchical multiple regressions, we found that gender identity, length, unpredictability, and time pressures predicted seeing one’s commute to work as a waste of time. The same predictors, except for time pressures, that were significant for commuting to work were also significant predictors from work. However, delays and congestion were additional predictors. Women reported that they viewed their commute to and from work as more of a waste of time. Limitations and future directions are discussed
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