26,402 research outputs found
Kant, Morality, and Hell
In this paper I argue that, although Kant argues that morality is independent of God (and hence, agrees with the Euthyphro), and rejects Divine Command Theory (or Theological Voluntarism), he believes that all moral duties are also the commands of God, who is a moral being, and who is morally required to punish those who transgress the moral law: "God’s justice is the precise allocation of punishments and rewards in accordance with men’s good or bad behavior." However, since we lack a strict proof of God's existence, we can still fulfill our duties from the motive of duty. if we did know that God exists, then this would undermine our pure moral motivation to do our duty, since we would have an even stronger interest in pleasing God through our good conduct. The effect of undermining our pure moral motivation would be to make us less eligible for divine reward, since God rewards us for doing our duty from the motive of duty
Genomic characterisation of an endometrial pathogenic <i>Escherichia coli</i> strain reveals the acquisition of genetic elements associated with extra-intestinal pathogenicity
<b>Background</b><p></p>
Strains of <i>Escherichia coli</i> cause a wide variety of intestinal and extra-intestinal diseases in both humans and animals, and are also often found in healthy individuals or the environment. Broadly, a strong phylogenetic relationship exists that distinguishes most <i>E. Coli</i> causing intestinal disease from those that cause extra-intestinal disease, however, isolates within a recently described subclass of Extra-Intestinal Pathogenic <i>E. Coli</i> (ExPEC), termed endometrial pathogenic <i>E. Coli</i>, tend to be phylogenetically distant from the vast majority of characterised ExPECs, and more closely related to human intestinal pathogens. In this work, we investigate the genetic basis for ExPEC infection in the prototypic endometrial pathogenic <i>E. Coli</i> strain MS499.<p></p>
<b>Results</b><p></p>
By investigating the genome of MS499 in comparison with a range of other E. coli sequences, we have discovered that this bacterium has acquired substantial lengths of DNA which encode factors more usually associated with ExPECs and less frequently found in the phylogroup relatives of MS499. Many of these acquired factors, including several iron acquisition systems and a virulence plasmid similar to that found in several ExPECs such as APEC O1 and the neonatal meningitis <i>E. Coli</i> S88, play characterised roles in a variety of typical ExPEC infections and appear to have been acquired recently by the evolutionary lineage leading to MS499.<p></p>
<b>Conclusions</b><p></p>
Taking advantage of the phylogenetic relationship we describe between MS499 and several other closely related <i>E. Coli</i> isolates from across the globe, we propose a step-wise evolution of a novel clade of sequence type 453 ExPECs within phylogroup B1, involving the recruitment of ExPEC virulence factors into the genome of an ancestrally non-extraintestinal <i>E. Coli</i>, which has repurposed this lineage with the capacity to cause extraintestinal disease. These data reveal the genetic components which may be involved in this phenotype switching, and argue that horizontal gene exchange may be a key factor in the emergence of novel lineages of ExPECs.<p></p>
Fixed-delay Interferometry for Doppler Extra-solar Planet Detection
We present a new technique based on fixed-delay interferometry for high
throughput, high precision and multi-object Doppler radial velocity (RV)
surveys for extra-solar planets. The Doppler measurements are conducted through
monitoring the stellar fringe phase shifts of the interferometer. High Doppler
sensitivity is achieved through optimizing the optical delay in the
interferometer and reducing photon noise by measuring multiple fringes over a
broadband. This broadband operation is performed through coupling the
interferometer with a low to medium resolution post-disperser. The total
Doppler sensitivity of this approach is, in theory, independent of dispersing
power of the post-disperser, which allows development of new generation RV
machines with much reduced size, high stability and low cost compared to
echelles. This technique has the potential to improve RV survey efficiency by
2-3 orders of magnitude over cross-dispersed echelle spectroscopy approach to
allow a full sky RV survey for planets once the instrument is operated as a
multi-object instrument and optimized for high throughput.
The simple interferometer response potentially allows this technique to be
operated at other wavelengths independent of popular iodine reference sources
to search for planets around early type stars, white dwarfs, and M, L and T
dwarfs for the first time.Comment: Accepted to ApJ Letters for publication, 11 pages, 2 figure
Three dimensional rotational angiography imaging of double aortic arch vascular ring
Three dimensional (3D) rotational angiography is a technique used increasingly for
imaging in congenital heart disease. Here the use of this technique for imaging of
double aortic arch vascular ring is described and the advantages of this modality. are discussed. 3D rotational angiography is an excellent tool for imaging of various vascular anomalies. It provides high quality accurate images through a quick and safe procedure.peer-reviewe
First High Contrast Imaging Using a Gaussian Aperture Pupil Mask
Placing a pupil mask with a gaussian aperture into the optical train of
current telescopes represents a way to attain high contrast imaging that
potentially improves contrast by orders of magnitude compared to current
techniques. We present here the first observations ever using a gaussian
aperture pupil mask (GAPM) on the Penn State near-IR Imager and Spectrograph
(PIRIS) at the Mt. Wilson 100 telescope. Two nearby stars were
observed, Eridani and Her A. A faint companion was detected
around Her A, confirming it as a proper motion companion. Furthermore,
the observed H and K magnitudes of the companion were used to constrain its
nature. No companions or faint structure were observed for Eridani.
We found that our observations with the GAPM achieved contrast levels similar
to our coronographic images, without blocking light from the central star. The
mask's performance also nearly reached sensitivities reported for other ground
based adaptive optics coronographs and deep HST images, but did not reach
theoretically predicted contrast levels. We outline ways that could improve the
performance of the GAPM by an order of magnitude or more.Comment: 8 pages, 4 figures, accepted by ApJ letter
Stochastic Physics, Complex Systems and Biology
In complex systems, the interplay between nonlinear and stochastic dynamics,
e.g., J. Monod's necessity and chance, gives rise to an evolutionary process in
Darwinian sense, in terms of discrete jumps among attractors, with punctuated
equilibrium, spontaneous random "mutations" and "adaptations". On an
evlutionary time scale it produces sustainable diversity among individuals in a
homogeneous population rather than convergence as usually predicted by a
deterministic dynamics. The emergent discrete states in such a system, i.e.,
attractors, have natural robustness against both internal and external
perturbations. Phenotypic states of a biological cell, a mesoscopic nonlinear
stochastic open biochemical system, could be understood through such a
perspective.Comment: 10 page
Explicit Lie-Poisson integration and the Euler equations
We give a wide class of Lie-Poisson systems for which explicit, Lie-Poisson
integrators, preserving all Casimirs, can be constructed. The integrators are
extremely simple. Examples are the rigid body, a moment truncation, and a new,
fast algorithm for the sine-bracket truncation of the 2D Euler equations.Comment: 7 pages, compile with AMSTEX; 2 figures available from autho
Spectrum of Sizes for Perfect Deletion-Correcting Codes
One peculiarity with deletion-correcting codes is that perfect
-deletion-correcting codes of the same length over the same alphabet can
have different numbers of codewords, because the balls of radius with
respect to the Levenshte\u{\i}n distance may be of different sizes. There is
interest, therefore, in determining all possible sizes of a perfect
-deletion-correcting code, given the length and the alphabet size~.
In this paper, we determine completely the spectrum of possible sizes for
perfect -ary 1-deletion-correcting codes of length three for all , and
perfect -ary 2-deletion-correcting codes of length four for almost all ,
leaving only a small finite number of cases in doubt.Comment: 23 page
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