441 research outputs found

    Cooking the Books: the Golem and the Ethics of Biotechnology

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    This working paper has three modest aims: (1) To present, in a succinct and accessible but not distorted fashion, ancient religious Jewish sources about a human-like entity called the golem and some of their later interpretations; (2) To distinguish our sources from the popular modern representation of the golem in Ashkenazi Jewish fiction and folktales, which has played a greater role in recent Jewish contributions to bioethics; (3) To suggest why our ancient sources on the golem, if we try to locate them in their own interpretive contexts, have a new relevance to anyone who is curious about the ethical significance of humanity’s rapidly increasing ability to intervene in biological creation. The paper is organized in three parts. The introduction offers a critical synopsis of dominant ways that experts in Jewish bioethics have recently invoked the golem. As will be shown, these experts have a high degree of consensus about the golem’s significance, they refer to a narrow range of sources, and they use a similar interpretive procedure to determine the meaning of their sources. These facts are related. They result in an interpretation of the golem that equates one nineteenth-century Eastern European legend with an image spanning millennia, scores of texts, and much of the Western world. Key variables, with divergent implications, have been lost in this equation. Therefore, in the second section, a broader picture of the golem is provided. Beginning with the noun’s sole appearance in the Bible (Psalm 139) and looking at a few rabbinic and Jewish mystical writings, we will use the work of scholars and close readings of canonical sources to reveal several neglected ways that Jewish sources have used the golem image in order to reflect upon the ethics of creation. In our conclusion, we will summarize the empirical and methodological consequences of these readings. Rather than pronounce on what the golem tells scientists (not) to do with biology, we will synthesize new ways that this image might help them, or any open-minded reader, to think about this vital issue

    Effect of Feeding Different Types of Byproducts and Concentrations Throughout a Beef Growing System on Ground Beef Color and Lipid Oxidation

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    The objective of this trial was to evaluate the effect of feeding different concentrations of wet distillers grains during winter backgrounding and either modified wet distillers grains or Sweet Bran® during the finishing phase on ground beef color and lipid oxidation. After a 14 day aging period, ground beef patties were made and placed in a simulated retail display for seven days. There were no overall differences in lipid oxidation between treatments but was a treatment by day interaction for discoloration. Ground beef from heifers finished with modified wet distillers grains discolored at a greater extent when compared to ground beef from heifers finished with Sweet Bran

    Observations of Mass Loss from the Transiting Exoplanet HD 209458b

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    Using the new Cosmic Origins Spectrograph (COS) on the {\it Hubble Space Telescope (HST)}, we obtained moderate-resolution, high signal/noise ultraviolet spectra of HD 209458 and its exoplanet HD 209458b during transit, both orbital quadratures, and secondary eclipse. We compare transit spectra with spectra obtained at non-transit phases to identify spectral features due to the exoplanet's expanding atmosphere. We find that the mean flux decreased by 7.8±1.37.8\pm 1.3% for the C II 1334.5323\AA\ and 1335.6854\AA\ lines and by 8.2±1.48.2\pm 1.4% for the Si III 1206.500\AA\ line during transit compared to non-transit times in the velocity interval --50 to +50 km s−1^{-1}. Comparison of the C II and Si III line depths and transit/non-transit line ratios shows deeper absorption features near --10 and +15 km s−1^{-1} and less certain features near --40 and +30--70 km s−1^{-1}, but future observations are needed to verify this first detection of velocity structure in the expanding atmosphere of an exoplanet. Our results for the C II lines and the non-detection of Si IV 1394.76\AA\ absorption are in agreement with \citet{Vidal-Madjar2004}, but we find absorption during transit in the Si III line contrary to the earlier result. The 8±18\pm 1% obscuration of the star during transit is far larger than the 1.5% obscuration by the exoplanet's disk. Absorption during transit at velocities between --50 and +50 km s−1^{-1} in the C II and Si III lines requires high-velocity ion absorbers, but models that assume that the absorbers are high-temperature thermal ions are inconsistent with the COS spectra. Assuming hydrodynamic model values for the gas temperature and outflow velocity at the limb of the outflow as seen in the C II lines, we find mass-loss rates in the range (8--40)×1010\times 10^{10} g s−1^{-1}.Comment: 25 pages, 4 figures, Astrophysical Journal in pres

    Characterizing the Habitable Zones of Exoplanetary Systems with a Large Ultraviolet/Visible/Near-IR Space Observatory

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    Understanding the surface and atmospheric conditions of Earth-size, rocky planets in the habitable zones (HZs) of low-mass stars is currently one of the greatest astronomical endeavors. Knowledge of the planetary effective surface temperature alone is insufficient to accurately interpret biosignature gases when they are observed in the coming decades. The UV stellar spectrum drives and regulates the upper atmospheric heating and chemistry on Earth-like planets, is critical to the definition and interpretation of biosignature gases, and may even produce false-positives in our search for biologic activity. This white paper briefly describes the scientific motivation for panchromatic observations of exoplanetary systems as a whole (star and planet), argues that a future NASA UV/Vis/near-IR space observatory is well-suited to carry out this work, and describes technology development goals that can be achieved in the next decade to support the development of a UV/Vis/near-IR flagship mission in the 2020s.Comment: Submitted in response to NASA call for white papers: "Large Astrophysics Missions to Be Studied by NASA Prior to the 2020 Decadal Survey

    Searching for Far-Ultraviolet Auroral/Dayglow Emission from HD209458b

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    We present recent observations from the HST-Cosmic Origins Spectrograph aimed at characterizing the auroral emission from the extrasolar planet HD209458b. We obtained medium-resolution (R~18-20,000) far-ultraviolet (1150-1700A) spectra at both the Phase 0.25 and Phase 0.75 quadrature positions as well as a stellar baseline measurement at secondary eclipse. This analysis includes a catalog of stellar emission lines and a star-subtracted spectrum of the planet. We present an emission model for planetary H2 emission, and compare this model to the planetary spectrum. No unambiguously identifiable atomic or molecular features are detected, and upper limits are presented for auroral/dayglow line strengths. An orbital velocity cross-correlation analysis finds a statistically significant (3.8 sigma) feature at +15 (+/- 20) km/s in the rest frame of the planet, at 1582 A. This feature is consistent with emission from H2 B-X (2-9) P(4) (lambda_{rest} = 1581.11 A), however the physical mechanism required to excite this transition is unclear. We compare limits on relative line strengths seen in the exoplanet spectrum with models of ultraviolet fluorescence to constrain the atmospheric column density of neutral hydrogen between the star and the planetary surface. These results support models of short period extrasolar giant planets with weak magnetic fields and extended atomic atmospheres.Comment: Accepted to ApJ. 12 pages, 5 figures, 4 table

    CARMA Millimeter-Wave Aperture Synthesis Imaging of the HD 32297 Debris Disk

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    We present the first detection and mapping of the HD 32297 debris disk at 1.3 mm with the Combined Array for Research in Millimeter-wave Astronomy (CARMA). With a sub-arcsecond beam, this detection represents the highest angular resolution (sub)mm debris disk observation made to date. Our model fits to the spectral energy distribution from the CARMA flux and new Spitzer MIPS photometry support the earlier suggestion that at least two, possibly three, distinct grain populations are traced by the current data. The observed millimeter map shows an asymmetry between the northeast and southwest disk lobes, suggesting large grains may be trapped in resonance with an unseen exoplanet. Alternatively, the observed morphology could result from the recent breakup of a massive planetesimal. A similar-scale asymmetry is also observed in scattered light but not in the mid-infrared. This contrast between asymmetry at short and long wavelengths and symmetry at intermediate wavelengths is in qualitative agreement with predictions of resonant debris disk models. With resolved observations in several bands spanning over three decades in wavelength, HD 32297 provides a unique testbed for theories of grain and planetary dynamics, and could potentially provide strong multi-wavelength evidence for an exoplanetary system.Comment: 4 pages, 4 figures; Accepted to ApJL: 25 Aug 200

    The MUSCLES Treasury Survey. IV. : Scaling relations for ultraviolet, Ca II K, and energetic particle fluxes from M dwarfs

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    Characterizing the UV spectral energy distribution (SED) of an exoplanet host star is critically important for assessing its planet's potential habitability, particularly for M dwarfs, as they are prime targets for current and near-term exoplanet characterization efforts and atmospheric models predict that their UV radiation can produce photochemistry on habitable zone planets different from that on Earth. To derive ground-based proxies for UV emission for use when Hubble Space Telescope (HST) observations are unavailable, we have assembled a sample of 15 early to mid-M dwarfs observed by HST and compared their nonsimultaneous UV and optical spectra. We find that the equivalent width of the chromospheric Ca ii K line at 3933 Å, when corrected for spectral type, can be used to estimate the stellar surface flux in ultraviolet emission lines, including H i Lyα. In addition, we address another potential driver of habitability: energetic particle fluxes associated with flares. We present a new technique for estimating soft X-ray and >10 MeV proton flux during far-UV emission line flares (Si iv and He ii) by assuming solar-like energy partitions. We analyze several flares from the M4 dwarf GJ 876 observed with HST and Chandra as part of the MUSCLES Treasury Survey and find that habitable zone planets orbiting GJ 876 are impacted by large Carrington-like flares with peak soft X-ray fluxes ≥10−3 W m−2 and possible proton fluxes ~102–103 pfu, approximately four orders of magnitude more frequently than modern-day Earth.Publisher PDFPeer reviewe

    Morphological Diversity between Culture Strains of a Chlorarachniophyte, Lotharella globosa

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    Chlorarachniophytes are marine unicellular algae that possess secondary plastids of green algal origin. Although chlorarachniophytes are a small group (the phylum of Chlorarachniophyta contains 14 species in 8 genera), they have variable and complex life cycles that include amoeboid, coccoid, and/or flagellate cells. The majority of chlorarachniophytes possess two or more cell types in their life cycles, and which cell types are found is one of the principle morphological criteria used for species descriptions. Here we describe an unidentified chlorarachniophyte that was isolated from an artificial coral reef that calls this criterion into question. The life cycle of the new strain includes all three major cell types, but DNA barcoding based on the established nucleomorph ITS sequences showed it to share 100% sequence identity with Lotharella globosa. The type strain of L. globosa was also isolated from a coral reef, but is defined as completely lacking an amoeboid stage throughout its life cycle. We conclude that L. globosa possesses morphological diversity between culture strains, and that the new strain is a variety of L. globosa, which we describe as Lotharella globosa var. fortis var. nov. to include the amoeboid stage in the formal description of L. globosa. This intraspecies variation suggest that gross morphological stages maybe lost rather rapidly, and specifically that the type strain of L. globosa has lost the ability to form the amoeboid stage, perhaps recently. This in turn suggests that even major morphological characters used for taxonomy of this group may be variable in natural populations, and therefore misleading
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