650 research outputs found
Kantâs Neglected Objection to the Ontological Argument
This paper argues that Kantâs most famous objection to the ontological argument -- that existence is not a real predicate -- is not, in fact, his most effective objection, and that his âneglected objectionâ to the argument deserves to be better known. It shows that Kant clearly anticipates William Roweâs later objection that the argument begs the question, and discusses why Kant himself seems to have overlooked the force of this criticism in his attempt to demolish the traditional proofs for Godâs existence
Rapid, multiplexed microfluidic phage display
The development of a method for high-throughput, automated proteomic screening could impact areas ranging from fundamental molecular interactions to the discovery of novel disease markers and therapeutic targets. Surface display techniques allow for efficient handling of large molecular libraries in small volumes. In particular,
phage display has emerged as a powerful technology for selecting peptides and proteins with enhanced, target-specific binding affinities. Yet, the process becomes cumbersome and time-consuming when multiple targets are involved.Here we demonstrate for the first time a microfluidic chip capable of identifying high affinity phage displayed peptides for multiple targets in just a single round and without the need for bacterial infection. The chip is shown to be able to yield well-established control consensus sequences while simultaneously
identifying new sequences for clinically important targets.
Indeed, the confined parameters of the device allow not only for highly controlled assay conditions but also introduce a significant time-reduction to the phage display process. We anticipate that this easily-fabricated, disposable device has the potential to impact areas
ranging from fundamental studies of protein, peptide, and molecular interactions, to applications such as fully automated proteomic screening
Structure and magnetic properties of the cubic oxide fluoride BaFeO2F
Fluorination of the parent oxide, BaFeO3- ÎŽ, with polyvinylidine fluoride gives rise to a cubic compound with a = 4.0603(4) Ă
at 298K. 57Fe Mössbauer spectra confirmed that all the iron is present as Fe3+. Neutron diffraction data showed complete occupancy of the anion sites indicating a composition BaFeO2F, with a large displacement of the iron off-site. The magnetic ordering temperature was determined as TN = 645±5K. Neutron diffraction data at 4.2K established G-type antiferromagnetism with a magnetic moment per Fe3+ ion of 3.95ÎŒB. However, magnetisation measurements indicated the presence of a weak ferromagnetic moment which is assigned to the canting of the antiferromagnetic structure. 57Fe Mössbauer spectra in the temperature range 10 to 300K were fitted with a model of fluoride ion distribution that retains charge neutrality of the perovskite unit cel
Self-Potential Signals Generated by the Corrosion of Buried Metallic Objects with Application to Contaminant Plumes
Large-amplitude (\u3e100 mV) negative electric (self)-potential anomalies are often observed in the vicinity of buried metallic objects and ore bodies or over groundwater plumes associated with organic contaminants. To explain the physical and chemical mechanisms that generate such electrical signals, a controlled laboratory experiment was carried out involving two metallic cylinders buried with vertical and horizontal orientations and centered through and in the capillary fringe within a sandbox. The 2D and 3D self-potential (SP) data were collected at several time steps along with collocated pH and redox potential measurements. Large dipolar SP and redox potential anomalies developed in association with the progressive corrosion of the vertical pipe, although no anomalies were observed in the vicinity of the horizontal pipe. This discrepancy was due to the orientation of the pipes with the vertical pipe subjected to a significantly larger EH gradient. Accounting for the electrical conductivity distribution, the SP data were inverted to recover the source current density vector field using a deterministic least-squares 4D (time-lapse) finite-element modeling approach. These results were then used to retrieve the 3D distribution of the redox potential along the vertical metallic cylinder. The results of the inversion were found to be in excellent agreement with the measured distribution of the redox potential. This experiment indicated that passively recorded electrical signals can be used to nonintrusively monitor corrosion processes. In addition, vertical electrical potential profiles measured through a mature hydrocarbon contaminated site were consistent with the sandbox observations, lending support to the geobattery model over organic contaminant plumes
Magnetic interactions in cubic-, hexagonal- and trigonal barium iron oxide fluoride, BaFeO2F
57Fe Mössbauer spectra have been recorded from the hexagonal (6H)- and trigonal (15R)- modifications of BaFeO2F and are compared with those previously recorded
from the cubic form of BaFeO2F. The spectra, recorded over a temperature range from 15 to 650K show that all of the iron in all the compounds is in the Fe3+ state. Spectra from the 6H- and 15R- modifications were successfully fitted with components that were related to the Fe(1) and Fe(2) structural sites in the 6H variant and to the Fe(1), Fe(2) and Fe(3) structural sites in the 15R form. The magnetic
ordering temperatures were determined as 597±3K for 6H-BaFeO2F and 636±3K for 15R-BaFeO2F. These values are surprisingly close to the value of 645±5K determined for the cubic form. The magnetic interactions in the three forms are compared with a view to explaining this similarity of magnetic ordering temperature.
Keywords : Mossbauer barium iron oxide fluorid
Assessing Media Campaigns Linking Marijuana Non-Use with Autonomy and Aspirations: âBe Under Your Own Influenceâ and ONDCPâs âAbove the Influenceâ
Two media-based interventions designed to reduce adolescent marijuana use ran concurrently from 2005 to 2009. Both interventions used similar message strategies, emphasizing marijuanaâs inconsistency with personal aspirations and autonomy. âBe Under Your Own Influenceâ was a randomized community and school trial replicating and extending a successful earlier intervention of the same name (Slater et al. Health Education Research 21:157â167, 2006). âAbove the Influenceâ is a continuing national television, radio, and print campaign sponsored by the Office of National Drug Control Policy (ONDCP). This study assessed the simultaneous impact of the interventions in the 20 U.S. communities. Results indicate that earlier effects of the âBe Under Your Own Influenceâ intervention replicated only in part and that the most plausible explanation of the weaker effects is high exposure to the similar but more extensive ONDCP âAbove the Influenceâ national campaign. Self-reported exposure to the ONDCP campaign predicted reduced marijuana use, and analyses partially support indirect effects of the two campaigns via aspirations and autonomy
Characterization of the acidic cold seep emplaced jarositic Golden Deposit, NWT, Canada, as an analogue for jarosite deposition on Mars
Surficial deposits of the OH-bearing iron sulfate mineral jarosite have been observed in several places on Mars, such as Meridiani Planum and Mawrth Vallis. The specific depositional conditions and mechanisms are not known, but by comparing martian sites to analogous locations on Earth, the conditions of formation and, thus, the martian depositional paleoenvironments may be postulated. Located in a cold semi-arid desert ~100 km east of Norman Wells, Northwest Territories, Canada, the Golden Deposit (GD) is visible from the air as a brilliant golden-yellow patch of unvegetated soil, approximately 140 m x 50 m. The GD is underlain by permafrost and consists of yellow sediment, which is precipitating from seeps of acidic, iron-bearing groundwater. On the surface, the GD appears as a patchwork of raised polygons, with acidic waters flowing from seeps in troughs between polygonal islands. Although UV-Vis-NIR spectral analysis detects only jarosite, mineralogy, as determined by X-Ray Diffraction and Inductively Coupled Plasma Emission Spectrometry, is predominantly natrojarosite and jarosite, with hydronium jarosite, goethite, quartz, clays, and small amounts of hematite. Water pH varies significantly over short distances depending on proximity to acid seeps, from 2.3 directly above seeps, to 5.7 several m downstream from seeps within the deposit, and up to 6.5 in ponds proximal to the deposit. Visual observations of microbial filament communities and phospholipid fatty acid analyses confirm that the GD is capable of supporting life for at least part of the year. Jarositic-bearing sediments extend beneath vegetation up to 70 m out from the deposit and are mixed with plant debris and minerals presumably weathered from bedrock and glacial till. This site is of particular interest because mineralogy (natrojarosite, jarosite, hematite, and goethite) and environmental conditions (permafrost and arid conditions) at the time of deposition are conceivably analogous to jarosite deposits on Mars. Most terrestrial analogues for Mars jarosites have been identified in temperate environments, where evaporation rates are very high and jarosites form along with other sulfates due to rapid evaporation (e.g. Rio Tinto, Spain; Western Australian acidic saline lake deposits). The GD is a rare example of an analogue site where jarosite precipitates under dominant freezing processes similar to those which could have prevailed on early Mars. Thus, the GD offers a new perspective on jarosite deposition by the upwelling of acidic waters through permafrost at Meridiani Planum and Mawrth Vallis, Mars. The GD also demonstrates that martian deposits may show considerably more chemical and mineral variability than indicated by the current remote sensing data sets
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