5,462 research outputs found
The Effect of Cattle, Sheep, and Other Factors on Aspen (Populus Tremuloides) Reproduction After Clear-Cut Logging in Southern Utah
Aspen is the most widespread deciduous tree of the western United States and the aspen type is important for water, forage, and wood products. Aspen reproduction on cutover areas was thought to be hindered by browsing and other factors, therefore a study was conducted to determine the effects of livestock, pocket gophers, disease, and snowpack damage on aspen reproduction during the first three years after clear-cutting. An enclosure was constructed and divided into nine paddocks. Controlled grazing by cattle and sheep was applied to six different paddocks during three summer periods. Three paddocks were protected from grazing. Results show that sheep utilized more sprouts than cattle, but controlled grazing by sheep or cattle did not prevent adequate aspen regeneration on good sites. Pocket gophers and disease appeared to be the most important decimating factors under controlled grazing. Sheep tended to concentrate on cutover areas so proper herding is needed to prevent misuse, especially the first and second years after initial sprouting
Advancing the Line: Increasing Empirical Literature on Justice-Involved Veterans
American veterans have long struggled with the aftereffects of combat exposure, repeated deployments to hostile countries, and extended time spent away from their families and loved ones. Historically, when veterans struggling with issues such as mental illness and substance abuse, which can be related back to their military service, came into contact with the criminal justice system, they were processed without regard to their unique military experience. Beginning in 2008, however, a new type of problem-solving court, veterans’ treatment courts (VTCs), have been increasingly adopted to target justice-involved veterans to address the distinct issues and challenges they face. VTCs are modeled after the successful drug and mental health court models and, as such, utilize therapeutic jurisprudence and effective intervention. However, they have not been subjected to the same amount of scholarly attention the aforementioned courts themselves have. This editorial introduction briefly reviews past and current research on justice-involved veterans and calls for the continued empirical assessment of VTCs to better understand both their impact and the military population they serve
Rhetorically Ascribed Meaning in Marketing: The Role of Narrative in Establishing Exchange Value
Use value and exchange value, concepts explored by Aristotle, are terms dealing with the natural function of an object and the object\u27s worth in an exchange, respectively. In this work, Aristotle\u27s concepts are applied to contemporary marketing practices and other aspects of culture in order to evaluate the way in which meaning is ascribed to objects. The role of the brand, for example, is to alter the exchange value of an object, while the use value can be left unchanged. Brands are indicative of exchange value because they have no substance to speak of, and they are a matter of convention; what they are and what they stand for is in no way fixed. Marketing practitioners develop brands largely by fusing objects with culture, and culture as well as cultural perceptions can change. As a reflection of culture, marketing practitioners use stories and identities in much the same way that culture independent of marketing would ascribe meaning. While branding and other marketing practices rely extensively on culture to form their bases, they are not the only source of cultural meaning because factors such as family and tradition also have influence. When factors such as these imbue objects with meaning, they, too, can affect exchange value, but they have origins outside the marketplace. I use the term narrative value to differentiate this source of meaning from marketing practices. Narrative value has to do with tradition and collective understandings of community, whereas brands are constructed by external means, as works of fiction. When culture is placed in objects as a reflection of the marketplace, the culture lacks the structure and durability of more traditional culture, and such ascribed meaning can be easily altered or eradicated. Narrative value, then, is an idea separate from marketing yet with the ability to impact worth in exchange
Evidence for J and H-band excess in classical T Tauri stars and the implications for disk structure and estimated ages
We argue that classical T Tauri stars (cTTs) possess significant non-
photospheric excess in the J and H bands. We first show that normalizing the
spectral energy distributions (SEDs) of cTTs to the J-band leads to a poor fit
of the optical fluxes, while normalizing the SEDs to the Ic-band produces a
better fit to the optical bands and in many cases reveals the presence of a
considerable excess at J and H. NIR spectroscopic veiling measurements from the
literature support this result. We find that J and H-band excesses correlate
well with the K-band excess, and that the J-K and H-K colors of the excess
emission are consistent with that of a black body at the dust sublimation
temperature (~ 1500-2000 K). We propose that this near-IR excess originates at
a hot inner rim, analogous to those suggested to explain the near-IR bump in
the SEDs of Herbig Ae/Be stars. To test our hypothesis, we use the model
presented by Dullemond et al. (2001) to fit the photometry data between 0.5 um
and 24 um of 10 cTTs associated with the Chamaeleon II molecular cloud. The
models that best fit the data are those where the inner radius of the disk is
larger than expected for a rim in thermal equilibrium with the photospheric
radiation field alone. In particular, we find that large inner rims are
necessary to account for the mid infrared fluxes (3.6-8.0 um) obtained by the
Spitzer Space Telescope. Finally, we argue that deriving the stellar
luminosities of cTTs by making bolometric corrections to the J-band fluxes
systematically overestimates these luminosities. The overestimated luminosities
translate into underestimated ages when the stars are placed in the H-R
diagram. Thus, the results presented herein have important implications for the
dissipation timescale of inner accretion disks.Comment: 45 pages, 13 figure
Cepheids and Long Period Variables in M33
We are conducting a long-term photometric survey of the nearby galaxy M33 to
discover Cepheids, eclipsing binaries, and long-period variables. The dataset
combines previously-obtained optical images from the DIRECT project with new
observations acquired at the WIYN 3.5m telescope. The entire data set spans
over 7 years with excellent synoptic coverage which will enable the discovery
and characterization of stars displaying variability over a wide range of
timescales (days, weeks, months, years). In this preliminary work we show
representative light curves of different variables we found so far in two
fields, color-magnitude diagrams, and optical Cepheid Period-Luminosity
relations for M33. The ultimate goal of the project is to provide an absolute
calibration of the Cepheid Period-Luminosity relation, and to study its
metallicity dependence at optical wavelengths.Comment: 3 pages, 6 figures. To appear in "Stellar Pulsation: Challenges for
Theory and Observation", Eds. J. Guzik and P. Bradle
Nature Of Transition Circumstellar Disks. I. The Ophiuchus Molecular Cloud
We have obtained millimeter-wavelength photometry, high-resolution optical spectroscopy, and adaptive optics near-infrared imaging for a sample of 26 Spitzer-selected transition circumstellar disks. All of our targets are located in the Ophiuchus molecular cloud (d similar to 125 pc) and have spectral energy distributions (SEDs) suggesting the presence of inner opacity holes. We use these ground-based data to estimate the disk mass, multiplicity, and accretion rate for each object in our sample in order to investigate the mechanisms potentially responsible for their inner holes. We find that transition disks are a heterogeneous group of objects, with disk masses ranging from <0.6 to 40 M(JUP) and accretion rates ranging from <10(-11) to 10(-7) M(circle dot) yr(-1), but most tend to have much lower masses and accretion rates than "full disks" (i.e., disks without opacity holes). Eight of our targets have stellar companions: six of them are binaries and the other two are triple systems. In four cases, the stellar companions are close enough to suspect they are responsible for the inferred inner holes. We find that nine of our 26 targets have low disk mass (<2.5 M(JUP)) and negligible accretion (<10(-11) M(circle dot) yr(-1)), and are thus consistent with photoevaporating (or photoevaporated) disks. Four of these nine non-accreting objects have fractional disk luminosities <10(-3) and could already be in a debris disk stage. Seventeen of our transition disks are accreting. Thirteen of these accreting objects are consistent with grain growth. The remaining four accreting objects have SEDs suggesting the presence of sharp inner holes, and thus are excellent candidates for harboring giant planets.NASA 1224608, 1230782, 1230779, 1407FONDECYT 1061199Basal CATA PFB 06/09ALMA FUND 31070021ALMA-Conicyt FUND 31060010National Science Foundation AST0-808144Spitzer Space Telescope Legacy Science ProgramAstronom
Herschel Observations of the T Cha Transition Disk: Constraining the Outer Disk Properties
T Cha is a nearby (d similar to 100 pc) transition disk known to have an optically thin gap separating optically thick inner and outer disk components. Huelamo et al. recently reported the presence of a low-mass object candidate within the gap of the T Cha disk, giving credence to the suspected planetary origin of this gap. Here we present the Herschel photometry (70, 160, 250, 350, and 500 mu m) of T Cha from the "Dust, Ice, and Gas in Time" Key Program, which bridges the wavelength range between existing Spitzer and millimeter data and provide important constraints on the outer disk properties of this extraordinary system. We model the entire optical to millimeter wavelength spectral energy distribution (SED) of T Cha (19 data points between 0.36 and 3300 mu m without any major gaps in wavelength coverage). T Cha shows a steep spectral slope in the far-IR, which we find clearly favors models with outer disks containing little or no dust beyond similar to 40 AU. The full SED can be modeled equally well with either an outer disk that is very compact (only a few AU wide) or a much larger one that has a very steep surface density profile. That is, T Cha's outer disk seems to be either very small or very tenuous. Both scenarios suggest a highly unusual outer disk and have important but different implications for the nature of T Cha. Spatially resolved images are needed to distinguish between the two scenarios.DIGIT Herschel Open Time Key ProgramNASAAlexander von Humboldt FoundationEuropean CommissionAgence Nationale pour la Recherche of France PERG06-GA-2009-256513, ANR-07-BLAN-0221, ANR-2010-JCJC-0504-01CNRS/INSU, FranceAstronom
Positive Vibrational Entropy of Chemical Ordering in FeV
Inelastic neutron scattering and nuclear resonant inelastic x-ray scattering were used to measure phonon spectra of FeV as a B2 ordered compound and as a bcc solid solution. The two data sets were combined to give an accurate phonon density of states, and the phonon partial densities of states for V and Fe atoms. Contrary to the behavior of ordering alloys studied to date, the phonons in the B2 ordered phase are softer than in the solid solution. Ordering increases the vibrational entropy by +0.22±0.03k_B/atom, which stabilizes the ordered phase to higher temperatures. First-principles calculations show that the number of electronic states at the Fermi level increases upon ordering, enhancing the screening between ions, and reducing the interatomic force constants. The effect of screening is larger at the V atomic sites than at the Fe atomic sites
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