Farming Muskoxen for Qiviut in Alaska: A Feasibility Study

Muskoxen (Ovibos moschatus) have been farmed since the 1960s for their fiber, called qiviut, a luxurious and highly valued underwool that is their primary insulation during the Arctic winter. Muskoxen are uniquely adapted to the Arctic. They thrive on local forages, do not require protection from the cold, and adapt well to many traditional husbandry practices. While muskoxen can be farmed for qiviut, the question remains whether it is an economically feasible and potentially sustainable enterprise in subarctic Alaska. This feasibility study was conducted using an enterprise budget for two herd sizes, 36 and 72 muskoxen, to estimate the principal costs and model different sales combinations. Under several revenue-generating scenarios, the feasibility study indicated a potential for economic viability of an established enterprise. The most profitable scenario for either herd size was selling all the qiviut as value-added yarn, coupled with livestock sales. In the absence of selling livestock, the enterprise was profitable at either scale assuming all the qiviut was sold as yarn. Selling qiviut solely as raw fiber was not projected to break even under the model parameters. The modeled enterprise emphasized the importance of value-added goods, economies of scale, low or zero opportunity costs, and the potential of a more active livestock market.Le boeuf musqué (Ovibos moschatus) est élevé depuis les années 1960 pour sa fibre, appelée qiviut, ce duvet somptueux et fort prisé qui sert d’isolant principal à cet animal pendant les hivers de l’Arctique. Le boeuf musqué est remarquablement bien adapté à l’Arctique. Il se nourrit d’aliments qui se trouvent dans la région, n’a pas besoin d’être protégé du froid et se prête bien à de nombreuses pratiques traditionnelles d’élevage. Bien qu’il soit possible d’élever le boeuf musqué pour son qiviut, il n’en reste pas moins qu’il faut se demander s’il s’agit là d’une entreprise rentable et durable dans le subarctique de l’Alaska. Cette étude de faisabilité a été réalisée à l’aide d’un budget d’entreprise pour des troupeaux de deux tailles, soit un troupeau de 36 boeufs musqués et un troupeau de 72 boeufs musqués, afin d’évaluer les principaux coûts et de modéliser diverses combinaisons de ventes. À l’aide de plusieurs scénarios de génération de revenus, l’étude de faisabilité a indiqué des possibilités de rentabilité économique pour une entreprise établie. Le scénario le plus rentable pour l’une ou l’autre taille de troupeau consistait à vendre tout le qiviut en tant que laine à valeur ajoutée, alliée à la vente du bétail. En l’absence de la vente de bétail, l’entreprise était rentable à l’une ou l’autre des échelles, en présumant que tout le qiviut était vendu en tant que laine. La vente du qiviut en tant que fibre brute seulement ne donnait pas lieu à la projection d’un seuil de rentabilité d’après les paramètres du modèle. L’entreprise ayant fait l’objet du modèle mettait l’accent sur l’importance des biens à valeur ajoutée, des économies d’échelle, de coûts faibles ou nuls et de la possibilité d’un marché plus actif pour le bétail

CfAIR2: Near Infrared Light Curves of 94 Type Ia Supernovae

CfAIR2 is a large homogeneously reduced set of near-infrared (NIR) light curves for Type Ia supernovae (SN Ia) obtained with the 1.3m Peters Automated InfraRed Imaging TELescope (PAIRITEL). This data set includes 4607 measurements of 94 SN Ia and 4 additional SN Iax observed from 2005-2011 at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona. CfAIR2 includes JHKs photometric measurements for 88 normal and 6 spectroscopically peculiar SN Ia in the nearby universe, with a median redshift of z~0.021 for the normal SN Ia. CfAIR2 data span the range from -13 days to +127 days from B-band maximum. More than half of the light curves begin before the time of maximum and the coverage typically contains ~13-18 epochs of observation, depending on the filter. We present extensive tests that verify the fidelity of the CfAIR2 data pipeline, including comparison to the excellent data of the Carnegie Supernova Project. CfAIR2 contributes to a firm local anchor for supernova cosmology studies in the NIR. Because SN Ia are more nearly standard candles in the NIR and are less vulnerable to the vexing problems of extinction by dust, CfAIR2 will help the supernova cosmology community develop more precise and accurate extragalactic distance probes to improve our knowledge of cosmological parameters, including dark energy and its potential time variation.Comment: 31 pages, 15 figures, 10 tables. Accepted to ApJS. v2 modified to more closely match journal versio

On Machine-Learned Classification of Variable Stars with Sparse and Noisy Time-Series Data

With the coming data deluge from synoptic surveys, there is a growing need for frameworks that can quickly and automatically produce calibrated classification probabilities for newly-observed variables based on a small number of time-series measurements. In this paper, we introduce a methodology for variable-star classification, drawing from modern machine-learning techniques. We describe how to homogenize the information gleaned from light curves by selection and computation of real-numbered metrics ("feature"), detail methods to robustly estimate periodic light-curve features, introduce tree-ensemble methods for accurate variable star classification, and show how to rigorously evaluate the classification results using cross validation. On a 25-class data set of 1542 well-studied variable stars, we achieve a 22.8% overall classification error using the random forest classifier; this represents a 24% improvement over the best previous classifier on these data. This methodology is effective for identifying samples of specific science classes: for pulsational variables used in Milky Way tomography we obtain a discovery efficiency of 98.2% and for eclipsing systems we find an efficiency of 99.1%, both at 95% purity. We show that the random forest (RF) classifier is superior to other machine-learned methods in terms of accuracy, speed, and relative immunity to features with no useful class information; the RF classifier can also be used to estimate the importance of each feature in classification. Additionally, we present the first astronomical use of hierarchical classification methods to incorporate a known class taxonomy in the classifier, which further reduces the catastrophic error rate to 7.8%. Excluding low-amplitude sources, our overall error rate improves to 14%, with a catastrophic error rate of 3.5%.Comment: 23 pages, 9 figure

Type IIb Supernova SN 2011dh: Spectra and Photometry from the Ultraviolet to the Near-Infrared

We report spectroscopic and photometric observations of the Type IIb SN 2011dh obtained between 4 and 34 days after the estimated date of explosion (May 31.5 UT). The data cover a wide wavelength range from 2,000 Angstroms in the UV to 2.4 microns in the NIR. Optical spectra provide line profiles and velocity measurements of HI, HeI, CaII and FeII that trace the composition and kinematics of the SN. NIR spectra show that helium is present in the atmosphere as early as 11 days after the explosion. A UV spectrum obtained with the STIS reveals that the UV flux for SN 2011dh is low compared to other SN IIb. The HI and HeI velocities in SN 2011dh are separated by about 4,000 km/s at all phases. We estimate that the H-shell of SN 2011dh is about 8 times less massive than the shell of SN 1993J and about 3 times more massive than the shell of SN 2008ax. Light curves (LC) for twelve passbands are presented. The maximum bolometric luminosity of $1.8 \pm 0.2 \times 10^{42}$ erg s$^{-1}$ occurred about 22 days after the explosion. NIR emission provides more than 30% of the total bolometric flux at the beginning of our observations and increases to nearly 50% of the total by day 34. The UV produces 16% of the total flux on day 4, 5% on day 9 and 1% on day 34. We compare the bolometric light curves of SN 2011dh, SN 2008ax and SN 1993J. The LC are very different for the first twelve days after the explosions but all three SN IIb display similar peak luminosities, times of peak, decline rates and colors after maximum. This suggests that the progenitors of these SN IIb may have had similar compositions and masses but they exploded inside hydrogen shells that that have a wide range of masses. The detailed observations presented here will help evaluate theoretical models for this supernova and lead to a better understanding of SN IIb.Comment: 23 pages, 14 figures, 9 tables, accepted by Ap

Utilizing Grassland Resources for Sub-Arctic Agriculture: Sustainable Muskox Farming in Alaska

The 2005 Millennium Ecosystem Assessment broadly classifies Alaska as a Polar Ecosystem, characterized as being frozen most of the year and underlain by permafrost. Despite this bleak portrayal, some of the largest herds of grazing ungulates are indigenous to Alaska - and thriving. This is both a testament to the resilience of grazing systems in general as well as a statement to the suitability of grazing systems specifically for Alaska. In a state economy dominated by nonrenewable resource extraction, agricultural production has remained largely undeveloped (Fried 2013). However, today there is increasing interest in local agricultural production with the goal of developing an economically diverse, sustainable agricultural model for Alaska. Muskoxen (Ovibos moschatus) are uniquely adapted to the arctic. They thrive on local forages, do not require protection from the cold and adapt well to many traditional husbandry practices. Muskoxen have been farmed since the 1960’s for their fiber, known as qiviut, a luxurious and highly valued underwool that is their primary insulation during the arctic winter. Adult muskoxen annually shed 1.5-2.5 kg of qiviut throughout their life. While muskoxen can be farmed for qiviut, the question remains whether this endeavor is a sustainable enterprise for northern farms? What impact will grazing practices have on pasture and soil health in sub-arctic environments? In this research, we investigated two aspects of the sustainability triad with respect to farming a non-traditional species, musk oxen, in Alaska: i) economic feasibility ii) potential impact of managed grazing on sub-arctic pasture ecology

GJ 3236: a new bright, very low-mass eclipsing binary system discovered by the MEarth observatory

We report the detection of eclipses in GJ 3236, a bright (I = 11.6) very low mass binary system with an orbital period of 0.77 days. Analysis of light- and radial velocity curves of the system yielded component masses of 0.38 +/- 0.02 and 0.28 +/- 0.02 Msol. The central values for the stellar radii are larger than the theoretical models predict for these masses, in agreement with the results for existing eclipsing binaries, although the present 5% observational uncertainties limit the significance of the larger radii to approximately 1 sigma. Degeneracies in the light curve models resulting from the unknown configuration of surface spots on the components of GJ 3236 currently dominate the uncertainties in the radii, and could be reduced by obtaining precise, multi-band photometry covering the full orbital period. The system appears to be tidally synchronized and shows signs of high activity levels as expected for such a short orbital period, evidenced by strong Halpha emission lines in the spectra of both components. These observations probe an important region of mass-radius parameter space around the predicted transition to fully-convective stellar interiors, where there are a limited number of precise measurements available in the literature.Comment: 14 pages, 5 figures, 10 tables, emulateapj format. Accepted for publication in Ap

The Rapidly Flaring Afterglow of the Very Bright and Energetic GRB 070125

We report on multi-wavelength observations, ranging from the X-ray to radio wave bands, of the IPN-localized gamma-ray burst GRB 070125. Spectroscopic observations reveal the presence of absorption lines due to O I, Si II, and C IV, implying a likely redshift of z = 1.547. The well-sampled light curves, in particular from 0.5 to 4 days after the burst, suggest a jet break at 3.7 days, corresponding to a jet opening angle of ~7.0 degrees, and implying an intrinsic GRB energy in the 1 - 10,000 keV band of around E = (6.3 - 6.9)x 10^(51) erg (based on the fluences measured by the gamma-ray detectors of the IPN network). GRB 070125 is among the brightest afterglows observed to date. The spectral energy distribution implies a host extinction of Av < 0.9 mag. Two rebrightening episodes are observed, one with excellent time coverage, showing an increase in flux of 56% in ~8000 seconds. The evolution of the afterglow light curve is achromatic at all times. Late-time observations of the afterglow do not show evidence for emission from an underlying host galaxy or supernova. Any host galaxy would be subluminous, consistent with current GRB host-galaxy samples. Evidence for strong Mg II absorption features is not found, which is perhaps surprising in view of the relatively high redshift of this burst and the high likelihood for such features along GRB-selected lines of sight.Comment: 50 pages, 9 figures, 5 tables Accepted to the Astrophysical Journa

Area, perimeter, height, and width of rectangle visibility graphs

A rectangle visibility graph (RVG) is represented by assigning to each vertex a rectangle in the plane with horizontal and vertical sides in such a way that edges in the graph correspond to unobstructed horizontal and vertical lines of sight between their corresponding rectangles. To discretize, we consider only rectangles whose corners have integer coordinates. For any given RVG, we seek a representation with smallest bounding box as measured by its area, perimeter, height, or width (height is assumed not to exceed width)