1,689 research outputs found
Modified Gravity Makes Galaxies Brighter
We investigate the effect of modifed gravity with screening mechanisms, such
as the chameleon or symmetron models, upon the structure of main sequence
stars. We find that unscreened stars can be significantly more luminous and
ephemeral than their screened doppelgangers. By embedding these stars into
dwarf galaxies, which can be unscreened for values of the parameters not yet
ruled out observationally, we show that the cumulative effect of their
increased luminosity can enhance the total galactic luminosity. We estimate
this enhancement and find that it can be considerable given model parameters
that are still under experimental scrutiny. By looking for systematic offsets
between screened dwarf galaxies in clusters and unscreened galaxies in voids,
these effects could form the basis of an independent observational test that
can potentially lower the current experimental bounds on the model independent
parameters of these theories by and order of magnitude or more.Comment: 16 pages, six figure
A Christian Guide to Body Stewardship, Diet and Exercise - 3rd Edition
This free textbook provides readers with a wealth of practical information regarding body stewardship, nutrition, and exercise, all written from a Christian worldview. While other textbooks provide readers with the why proper nutrition and regular exercise is important, this textbook takes it one step further and provides readers with the how . Each chapter is filled with helpful charts, tables, and figures that equip readers with tangible resources and recommendations they can use to put into practice the various concepts being introduced. Additionally, each chapter is written from a Christian worldview recognizing that the human body was created for a purpose, and through Godly stewardship of our bodies, we can more effectively worship our creator.https://digitalcommons.cedarville.edu/cedrus_press_publications/1024/thumbnail.jp
A Christian Guide to Body Stewardship, Diet and Exercise
This free textbook provides readers with a wealth of practical information regarding body stewardship, nutrition, and exercise, all written from a Christian worldview. While other textbooks provide readers with the why proper nutrition and regular exercise is important, this textbook takes it one step further and provides readers with the how . Each chapter is filled with helpful charts, tables, and figures that equip readers with tangible resources and recommendations they can use to put into practice the various concepts being introduced. Additionally, each chapter is written from a Christian worldview recognizing that the human body was created for a purpose, and through Godly stewardship of our bodies, we can more effectively worship our creator.https://digitalcommons.cedarville.edu/cedrus_press_publications/1022/thumbnail.jp
Measuring Individual-Level Resource Specialization
Many apparently generalized species are in fact composed of individual specialists that use a small subset of the population’s resource distribution. Niche variation is usually established by testing the null hypothesis that individuals draw from a common resource distribution. This approach encourages a publication bias in which negative results are rarely reported, and obscures variation in the degree of individual specialization, limiting our ability to carry out comparative studies of the causes or consequences of niche variation. To facilitate studies of the degree of individual specialization, this paper outlines four quantitative indices of intrapopulation variation in resource use. Traditionally, such variation has been measured by partitioning the population’s total niche width into within- and between-individual, sex, or phenotype components. We suggest two alternative measures that quantify the mean resource overlap between an individual and its population, and we discuss the advantages and disadvantages of all four measures. The utility of all indices depends on the quality of the empirical data. If resources are measured in a coarse-grained manner, individuals may falsely appear generalized. Alternatively, specialization may be overestimated by cross-sectional sampling schemes where diet variation can reflect a patchy environment. Isotope ratios, parasites, or diet–morphology correlations can complement cross-sectional data to establish temporal consistency of individual specialization
Large Mass, Entry, Descent and Landing Sensitivity Results for Environmental, Performance, and Design Parameters
Landing on Mars has been a challenging task. Past NASA missions have shown resilience to increases in spacecraft mass by scaling back requirements such as landing site altitude, landing site location and arrival time. Knowledge of the partials relating requirements to mass is critical for mission designers to understand so that the project can retain margin throughout the process. Looking forward to new missions that will land 1.5 metric tons or greater, the current level of technology is insufficient, and new technologies will need to be developed. Understanding the sensitivity of these new technologies to requirements is the purpose of this paper
Pump Pulse Bandwidth-Activated Nonlinear Phononic Coupling in CdWO
To control structure-function relationships in solids with light, we must
harness the shape of the potential energy surface, as expressed in anharmonic
coupling coefficients. We use two-dimensional terahertz (THz) spectroscopy to
identify trilinear coupling between sets of vibrational modes in CdWO. It
is generally understood that efficient trilinear coupling occurs when the
frequencies of two coupled modes add or subtract to the frequency of the third
mode. Interestingly, we observe that this condition is not necessary: the THz
driving-pulse itself can activate the coupling by contributing broad frequency
content to the initial motion of the excited modes. Understanding that the
bandwidth of the driving force can activate energy-flow pathways has broad
implications for coherent control of collective modes using intense THz light
pulses.Comment: 27 Pages, 15 Figure
Editorial: Small cetacean conservation: Current challenges and opportunities
Dolphins (oceanic and river dolphins; Delphinidae, Iniidae, Lipotidae, Pontoporiidae, Platanistidae) and porpoises (Phocoenidae) are the smallest members of the odontocete suborder. These species have colonized most aquatic ecosystems globally, from rivers to deep oceanic habitats, and from tropical to polar waters. Due to their habitat preferences, high metabolic rates, foraging behaviors, and diets, small cetaceans exhibit a wide range of ecological roles and functions across ecosystems where they occur and have the potential to affect communities via multiple pathways (top-down, bottom-up effects, and a range of behavior-mediated processes, Kiszka et al.). Dolphins and porpoises have also generated significant interest from the scientific community and more broadly by human societies since antiquity, with research on these animals increasing exponentially over the past 40-50 years. Despite protection by a range of international conventions (e.g., Convention on Migratory Species, Convention on the Trade of Endangered Species) and national legislation in most countries, some species are at increasing risk of decline and extirpation in aquatic habitats worldwide, with losses driven by a range of direct and indirect impacts from human activities. Today, more than 20% of species of oceanic dolphins, half of all species of porpoise, and all river dolphins are threatened with extinctionFil: Kiszka, Jeremy J.. Florida International University; Estados UnidosFil: Bejder, Lars. University of Hawaii at Manoa; Estados UnidosFil: Davis, Randall. Texas A&M University; Estados UnidosFil: Harcourt, Rob. Macquarie University; AustraliaFil: Meekan, Mark. University of Western Australia; AustraliaFil: Rodriguez, Diego Horacio. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Stockin, Karen A.. Massey University; Nueva Zeland
Be-10 age constraints on latest Pleistocene and Holocene cirque glaciation across the western United States
Paleoclimate: A rocky reworking of Holocene glaciology New dating of glacially-deposited rocks substantially revises our understanding of the waxing and waning of ice since the last glacial maximum. Glaciologists have long thought that moraines throughout the western United States represent ‘neoglacial’ advances about 6,000 years ago. Now, a multi-institution team led by Shaun Marcott at the University of Wisconsin-Madison has found — using cosmogenic isotopes — that these terminal deposits left by advancing glaciers are instead 9,000 to 15,000 years old. The research advances prior work by using absolute, not relative ages, and documents that glaciers retreated after the last glacial maximum ~ 21,000 years ago, fluctuated locally throughout much of the Holocene, and re-advanced during the Little Ice Age of a few hundred years ago. Glacial advances that might have occurred during the neoglacial were wiped away by the more extensive glaciations of the Little Ice Age
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