1,901 research outputs found
The implementation of a home-based isometric wall squat intervention using ratings of perceived exertion to select and control exercise intensity: a pilot study in normotensive and pre-hypertensive adults.
Isometric exercise (IE) and isometric wall squat (IWS) training have been shown to be effective methods of reducing arterial blood pressure. However, most IE interventions require methodologies and equipment that could present a barrier to participation. Therefore, this study aimed to examine the effectiveness of an accessible RPE prescribed IWS intervention. Thirty normotensive and pre-hypertensive adults were randomly assigned to a control group or one of two 4-week home-based IWS intervention groups: the first group conducted IWS exercise where intensity was prescribed and monitored using RPE (RPE-EX), whilst the other used a previously validated HR prescription method (HR-EX). Resting and ambulatory heart rate (HR) and blood pressure (BP) were measured pre- and post-intervention. Minimum clinically important differences (MCID; - 5 mmHg) in SBP and/or DBP were shown in 100% of intervention participants. Statistically significant reductions were shown in resting seated BP (RPE-EX: SBP: - 9 ± 6, DBP: - 6 ± 4, MAP: - 6 ± 3 mmHg; HR-EX: SBP: - 14 ± 6, DBP: - 6 ± 4, MAP: - 8 ± 4 mmHg), supine BP (RPE-EX: SBP: - 8 (- 5), DBP: - 8 (- 7), MAP: - 8 (- 4) mmHg; HR-EX: SBP: - 5 (- 4), MAP - 5 (- 4) mmHg), and ambulatory SBP (RPE-EX: - 8 ± 6 mmHg; HR-EX: - 10 ± 4 mmHg) following the interventions. There were no statistically significant differences between intervention groups in the magnitude of BP reduction. RPE prescribed IWS exercise can provide an effective and more accessible method for reducing BP at home, providing reductions comparable to the current HR-based prescription method. [Abstract copyright: © 2023. The Author(s).
The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets
The size of a planet is an observable property directly connected to the
physics of its formation and evolution. We used precise radius measurements
from the California-Kepler Survey (CKS) to study the size distribution of 2025
planets in fine detail. We detect a factor of 2 deficit
in the occurrence rate distribution at 1.5-2.0 R. This gap splits
the population of close-in ( < 100 d) small planets into two size regimes:
R < 1.5 R and R = 2.0-3.0 R, with few planets in
between. Planets in these two regimes have nearly the same intrinsic frequency
based on occurrence measurements that account for planet detection
efficiencies. The paucity of planets between 1.5 and 2.0 R supports
the emerging picture that close-in planets smaller than Neptune are composed of
rocky cores measuring 1.5 R or smaller with varying amounts of
low-density gas that determine their total sizes.Comment: Paper III in the California-Kepler Survey series, accepted to the
Astronomical Journa
The California-Kepler Survey. II. Precise Physical Properties of 2025 Kepler Planets and Their Host Stars
We present stellar and planetary properties for 1305 Kepler Objects of
Interest (KOIs) hosting 2025 planet candidates observed as part of the
California-Kepler Survey. We combine spectroscopic constraints, presented in
Paper I, with stellar interior modeling to estimate stellar masses, radii, and
ages. Stellar radii are typically constrained to 11%, compared to 40% when only
photometric constraints are used. Stellar masses are constrained to 4%, and
ages are constrained to 30%. We verify the integrity of the stellar parameters
through comparisons with asteroseismic studies and Gaia parallaxes. We also
recompute planetary radii for 2025 planet candidates. Because knowledge of
planetary radii is often limited by uncertainties in stellar size, we improve
the uncertainties in planet radii from typically 42% to 12%. We also leverage
improved knowledge of stellar effective temperature to recompute incident
stellar fluxes for the planets, now precise to 21%, compared to a factor of two
when derived from photometry.Comment: 13 pages, 4 figures, 4 tables, accepted for publication in AJ; full
versions of tables 3 and 4 are include
The California-Kepler Survey. I. High Resolution Spectroscopy of 1305 Stars Hosting Kepler Transiting Planets
The California-Kepler Survey (CKS) is an observational program to improve our
knowledge of the properties of stars found to host transiting planets by NASA's
Kepler Mission. The improvement stems from new high-resolution optical spectra
obtained using HIRES at the W. M. Keck Observatory. The CKS stellar sample
comprises 1305 stars classified as Kepler Objects of Interest, hosting a total
of 2075 transiting planets. The primary sample is magnitude-limited (Kp < 14.2)
and contains 960 stars with 1385 planets. The sample was extended to include
some fainter stars that host multiple planets, ultra short period planets, or
habitable zone planets. The spectroscopic parameters were determined with two
different codes, one based on template matching and the other on direct
spectral synthesis using radiative transfer. We demonstrate a precision of 60 K
in effective temperature, 0.10 dex in surface gravity, 0.04 dex in [Fe/H], and
1.0 km/s in projected rotational velocity. In this paper we describe the CKS
project and present a uniform catalog of spectroscopic parameters. Subsequent
papers in this series present catalogs of derived stellar properties such as
mass, radius and age; revised planet properties; and statistical explorations
of the ensemble. CKS is the largest survey to determine the properties of
Kepler stars using a uniform set of high-resolution, high signal-to-noise ratio
spectra. The HIRES spectra are available to the community for independent
analyses.Comment: 20 pages, 19 figures, accepted for publication in AJ; a full version
of Table 5 is included as tab_cks.csv and tab_cks.te
Working with simple machines
A set of examples is provided that illustrate the use of work as applied to
simple machines. The ramp, pulley, lever and hydraulic press are common
experiences in the life of a student and their theoretical analysis therefore
makes the abstract concept of work more real. The mechanical advantage of each
of these systems is also discussed so that students can evaluate their
usefulness as machines.Comment: 9 pages, 4 figure
Australia\u27s health 1992 : the third biennial report of the Australian Institute of Health and Welfare
Australia\u27s Health is the most comprehensive and authoritative source of national information on health in Australia. Australia\u27s Health is published mid-year in even-numbered years and provides national statistics and related information that form a record of health status, service provision and expenditure in Australia
Author Correction: A consensus-based transparency checklist.
An amendment to this paper has been published and can be accessed via a link at the top of the paper
Four sub-Saturns with dissimilar densities: windows into planetary cores and envelopes
We present results from a Keck/HIRES radial velocity campaign to study four sub-Saturn-sized planets, K2-27b, K2-32b, K2-39b, and K2-108b, with the goal of understanding their masses, orbits, and heavy-element enrichment. The planets have similar sizes (RP=4.5-5.5 ), but have dissimilar masses (MP=16-60 ), implying a diversity in their core and envelope masses. K2-32b is the least massive (MP = 16.5 ± 2.7 M) and orbits in close proximity to two sub-Neptunes near a 3:2:1 period commensurability. K2-27b and K2-39b are significantly more massive at MP = 30.9 ± 4.6 M and MP = 39.8 ± 4.4 M, respectively, and show no signs of additional planets. K2-108b is the most massive at MP = 59.4 ± 4.4 M, implying a large reservoir of heavy elements of about ≈50 . Sub-Saturns as a population have a large diversity in planet mass at a given size. They exhibit remarkably little correlation between mass and size; sub-Saturns range from ≈6-60 M, regardless of size. We find a strong correlation between planet mass and host star metallicity, suggesting that metal-rich disks form more massive planet cores. The most massive sub-Saturns tend to lack detected companions and have moderately eccentric orbits, perhaps as a result of a previous epoch of dynamical instability. Finally, we observe only a weak correlation between the planet envelope fraction and present-day equilibrium temperature, suggesting that photo-evaporation does not play a dominant role in determining the amount of gas sub-Saturns accrete from their protoplanetary disks
K2-66b and K2-106b: Two Extremely Hot Sub-Neptune-size Planets with High Densities
We report precise mass and density measurements of two extremely hot sub-Neptune-size planets from the K2 mission using radial velocities, K2 photometry, and adaptive optics imaging. K2-66 harbors a close-in sub-Neptune-sized (2.49_(-0.24)^(+0.34)R_⊕) planet (K2-66b) with a mass of 21.3 ± 3.6 M_⊕. Because the star is evolving up the subgiant branch, K2-66b receives a high level of irradiation, roughly twice the main-sequence value. K2-66b may reside within the so-called "photoevaporation desert," a domain of planet size and incident flux that is almost completely devoid of planets. Its mass and radius imply that K2-66b has, at most, a meager envelope fraction (<5%) and perhaps no envelope at all, making it one of the largest planets without a significant envelope. K2-106 hosts an ultra-short-period planet (P = 13.7 hr) that is one of the hottest sub-Neptune-size planets discovered to date. Its radius (1.82_(-0.14)^(+0.20) R_⊕) and mass (9.0 ± 1.6 M_⊕) are consistent with a rocky composition, as are all other small ultra-short-period planets with well-measured masses. K2-106 also hosts a larger, longer-period planet (R_p = 2.77_(-0.23^(+0.37)R_⊕, P = 13.3 days) with a mass less than 24.4 M_⊕ at 99.7% confidence. K2-66b and K2-106b probe planetary physics in extreme radiation environments. Their high densities reflect the challenge of retaining a substantial gas envelope in such extreme environments
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