2,866 research outputs found
Targeted delivery of platinum-based anticancer complexes
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
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
Recommended from our members
Birth seasonality studies in a large Prader-Willi syndrome cohort.
Prader-Willi syndrome (PWS) is generally due to sporadic paternal deletions of the chromosome 15q11-q13 region followed by maternal disomy 15. Advanced maternal age is more commonly seen in those with maternal disomy 15. Environmental factors (e.g., drug use, occupational chemical exposure, infectious agents, and irradiation) could account for chromosome changes. Previous evidence of differences in male and female gametogenesis could suggest an environmental role in the causation of the paternal 15q11-q13 deletion seen in PWS. Certain occupations such as hydrocarbon-exposing occupations (e.g., landscaping, farming, and painting) and viral exposure (e.g., human coronavirus 229E causing upper respiratory infections in adults with an incorporation site in the human genome at chromosome 15q11) can be seasonal in nature and contribute to chromosome damage. To assess, we reviewed birth seasonality data in a large cohort of individuals with PWS recruited nationally (N = 355) but no significant differences were seen by month between those with the 15q11-q13 deletion compared with maternal disomy 15 when analyzing quarterly seasonal patterns. Although early evidence supported birth seasonality differences in PWS, a larger number of individuals in our recent study using advanced genetic testing methods did not find this observation
A 4-Planet System Orbiting the K0V Star HD 141399
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
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
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
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
Recommended from our members
Early Diagnosis in Prader-Willi Syndrome Reduces Obesity and Associated Co-Morbidities.
Prader-Willi syndrome (PWS) is an imprinting genetic disorder characterized by lack of expression of genes on the paternal chromosome 15q11-q13 region. Growth hormone (GH) replacement positively influences stature and body composition in PWS. Our hypothesis was that early diagnosis delays onset of obesity in PWS. We studied 352 subjects with PWS, recruited from the NIH Rare Disease Clinical Research Network, to determine if age at diagnosis, ethnicity, gender, and PWS molecular class influenced the age they first become heavy, as determined by their primary care providers, and the age they first developed an increased appetite and began seeking food. The median ages that children with PWS became heavy were 10 years, 6 years and 4 years for age at diagnosis < 1 year, between 1 and 3 years, and greater than 3 years of age, respectively. The age of diagnosis and ethnicity were significant factors influencing when PWS children first became heavy (p < 0.01), however gender and the PWS molecular class had no influence. Early diagnosis delayed the onset of becoming heavy in individuals with PWS, permitting early GH and other treatment, thus reducing the risk of obesity-associated co-morbidities. Non-white individuals had an earlier onset of becoming heavy
- …