346 research outputs found
Changing and unchanging values in the world of the future, November 8, 9, and 10, 2001
This repository item contains a single issue of the Pardee Conference Series, a publication series that began publishing in 2006 by the Boston University Frederick S. Pardee Center for the Study of the Longer-Range Future. This was the Center's Inaugural Conference that took place during November 8, 9, and 10, 2001. Organized by David Fromkin, Director Frederick S. Pardee Center for the Study of the Longer-Range Future. Co-Sponsored by Boston University and Carnegie Council on Ethics and International Affairs.This conference brought together a discussion of different perspectives on what future paradigm shifts will look like – in government, in foreign policy, in what constitutes “classics,” in economic and religious modes, and changes in the interaction between these values. The conference agreed that today’s Western society values democracy, constitutionalism, liberalism, rule of law, open society, and market economy. These are not contingent upon one another and may change. But the “needs and aspirations” of humanity will at their most essential core remain the same. The amount and type of power given to governments is not a fixed thing, and developments in the meaning of democracy and how it is achieved may illustrate this
Updated Parameters and a New Transmission Spectrum of HD 97658b
Recent years have seen increasing interest in the characterization of sub-Neptune-sized planets because of their prevalence in the Galaxy, contrasted with their absence in our solar system. HD 97658 is one of the brightest stars hosting a planet of this kind, and we present the transmission spectrum of this planet by combining four Hubble Space Telescope transits, 12 Spitzer/IRAC transits, and eight MOST transits of this system. Our transmission spectrum has a higher signal-to-noise ratio than those from previous works, and the result suggests that the slight increase in transit depth from wavelength 1.1–1.7 μm reported in previous works on the transmission spectrum of this planet is likely systematic. Nonetheless, our atmospheric modeling results are inconclusive, as no model provides an excellent match to our data. Nonetheless, we find that atmospheres with high C/O ratios (C/O ≳ 0.8) and metallicities of ≳100× solar metallicity are favored. We combine the mid-transit times from all of the new Spitzer and MOST observations and obtain an updated orbital period of P = 9.489295 ± 0.000005, with a best-fit transit time center at T₀ = 2456361.80690 ± 0.00038 (BJD). No transit timing variations are found in this system. We also present new measurements of the stellar rotation period (34 ± 2 days) and stellar activity cycle (9.6 yr) of the host star HD 97658. Finally, we calculate and rank the Transmission Spectroscopy Metric of all confirmed planets cooler than 1000 K and with sizes between 1 R⊕ and 4 R⊕. We find that at least a third of small planets cooler than 1000 K can be well characterized using James Webb Space Telescope, and of those, HD 97658b is ranked fifth, meaning that it remains a high-priority target for atmospheric characterization
Understanding the Impacts of Stellar Companions on Planet Formation and Evolution: A Survey of Stellar and Planetary Companions within 25 pc
We explore the impact of outer stellar companions on the occurrence rate of giant planets detected with radial velocities. We searched for stellar and planetary companions to a volume-limited sample of solar-type stars within 25 pc. Using adaptive optics imaging observations from the Lick 3 m and Palomar 200" Telescopes, we characterized the multiplicity of our sample stars, down to the bottom of the main sequence. With these data, we confirm field star multiplicity statistics from previous surveys. We additionally combined three decades of radial velocity (RV) data from the California Planet Search with newly collected RV data from Keck/HIRES and the Automated Planet Finder/Levy Spectrometer to search for planetary companions in these same systems. Using an updated catalog of both stellar and planetary companions, as well as detailed injection/recovery tests to determine our sensitivity and completeness, we measured the occurrence rate of planets among the single- and multiple-star systems. We found that planets with masses in the range of 0.1–10 M_J and with semimajor axes of 0.1–10 au have an occurrence rate of 0.18^(+0.04)_(−0.03) planets per star when they orbit single stars and an occurrence rate of 0.12 ± 0.04 planets per star when they orbit a star in a binary system. Breaking the sample down by the binary separation, we found that only one planet-hosting binary system had a binary separation 100 au and 0.04^(+0.04)_(−0.02) planets per star for binaries with separation a_B 100 au. Finally, we found evidence that giant planets in binary systems have a different semimajor-axis distribution than their counterparts in single-star systems. The planets in the single-star sample had a significantly higher occurrence rate outside of 1 au than inside 1 au by nearly 4σ, in line with expectations that giant planets are most common near the snow line. However, the planets in the wide binary systems did not follow this distribution, but rather had equivalent occurrence rates interior and exterior to 1 au. This may point to binary-mediated planet migration acting on our sample, even in binaries wider than 100 au
The California Legacy Survey III. On The Shoulders of (Some) Giants: The Relationship between Inner Small Planets and Outer Massive Planets
We use a high-precision radial velocity survey of FGKM stars to study the
conditional occurrence of two classes of planets: close-in small planets
(0.023--1 au, 2--30 Earth masses) and distant giant planets (0.23--10 au,
30--6000 Earth masses). We find that of systems with a
close-in, small planet also host an outer giant, compared to
for stars irrespective of small planet presence. This
implies that small planet hosts may be enhanced in outer giant occurrence
compared to all stars with significance. Conversely, we estimate
that of cold giant hosts also host an inner small planet,
compared to of stars irrespective of cold giant
presence. We also find that more massive and close-in giant planets are not
associated with small inner planets. Specifically, our sample indicates that
small planets are less likely to host outer giant companions more massive than
approximately 120 Earth masses and within 0.3--3 au than to host less massive
or more distant giant companions, with 2.2 confidence. This
implies that massive gas giants within 0.3--3 au may suppress inner small
planet formation. Additionally, we compare the host-star metallicity
distributions for systems with only small planets and those with both small
planets and cold giants. In agreement with previous studies, we find that stars
in our survey that only host small planets have a metallicity distribution that
is consistent with the broader solar-metallicity-median sample, while stars
that host both small planets and gas giants are distinctly metal-rich with
2.3 confidence.Comment: Reposted on arxiv after journal acceptance and alterations in
response to reviewer comment
Polymorphisms in Plasmodium falciparum chloroquine resistance transporter and multidrug resistance 1 genes: parasite risk factors that affect treatment outcomes for P. falciparum malaria after artemether-lumefantrine and artesunate-amodiaquine.
Adequate clinical and parasitologic cure by artemisinin combination therapies relies on the artemisinin component and the partner drug. Polymorphisms in the Plasmodium falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance 1 (pfmdr1) genes are associated with decreased sensitivity to amodiaquine and lumefantrine, but effects of these polymorphisms on therapeutic responses to artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) have not been clearly defined. Individual patient data from 31 clinical trials were harmonized and pooled by using standardized methods from the WorldWide Antimalarial Resistance Network. Data for more than 7,000 patients were analyzed to assess relationships between parasite polymorphisms in pfcrt and pfmdr1 and clinically relevant outcomes after treatment with AL or ASAQ. Presence of the pfmdr1 gene N86 (adjusted hazards ratio = 4.74, 95% confidence interval = 2.29 - 9.78, P < 0.001) and increased pfmdr1 copy number (adjusted hazards ratio = 6.52, 95% confidence interval = 2.36-17.97, P < 0.001 : were significant independent risk factors for recrudescence in patients treated with AL. AL and ASAQ exerted opposing selective effects on single-nucleotide polymorphisms in pfcrt and pfmdr1. Monitoring selection and responding to emerging signs of drug resistance are critical tools for preserving efficacy of artemisinin combination therapies; determination of the prevalence of at least pfcrt K76T and pfmdr1 N86Y should now be routine
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