186 research outputs found
Next to Leading Order Semi-inclusive Spin Asymmetries
We have computed semi-inclusive spin asymmetries for proton and deuteron
targets including next to leading order (NLO) QCD corrections and contributions
coming from the target fragmentation region. These corrections have been
estimated using NLO fragmentation functions, parton distributions and also a
model for spin dependent fracture functions which is proposed here. We have
found that NLO corrections are small but non-negligible in a scheme where
gluons are polarised and that our estimate for target fragmentation effects
does not modify significantly charged asymmetries but affects the so called
difference asymmetries.Comment: Latex, 14 pages, 6 figures in 4 Postcript file
Scale Dependence of Polarized DIS Asymmetries
We compare the dependence of the polarized deep inelastic scattering
proton asymmetry, driven by the leading order Altarelli Parisi evolution
equations, to those arising from fixed order and
approximations. It is shown that the evolution effects associated with gluons,
which are not properly taken into account by the leading order approximation,
cannot be neglected in the analysis of the most recent experimental data.Comment: Latex file, (9 figures in postcript available from
[email protected]
Factorization in Semi-Inclusive Polarized Deep Inelastic Scattering
We calculate and analize the one-particle inclusive
cross section in polarized deep inelastic lepton-hadron scattering, using
dimensional regularization and the HVBM prescription for . We discuss
the factorization of all the collinear singularities related to the process,
particularly those which are absorbed in the redefinition of the spin dependent
analogue of the recently introduced fracture functions. This is done in the
usual scheme and in another one, called ,
which factorizes soft contributions and guarantees the axial current
(non)conservation properties.Comment: 16 pages, figures included using FEYNMAN macr
On the turbulent flow in piston engines: Coupling of statistical theory quantities and instantaneous turbulence
A Biomechanical Analysis of Ventral Furrow Formation in the Drosophila Melanogaster Embryo
The article provides a biomechanical analysis of ventral furrow formation in the Drosophila melanogaster embryo. Ventral furrow formation is the first large-scale morphogenetic movement in the fly embryo. It involves deformation of a uniform cellular monolayer formed following cellularisation, and has therefore long been used as a simple system in which to explore the role of mechanics in force generation. Here we use a quantitative framework to carry out a systematic perturbation analysis to determine the role of each of the active forces observed. The analysis confirms that ventral furrow invagination arises from a combination of apical constriction and apical–basal shortening forces in the mesoderm, together with a combination of ectodermal forces. We show that the mesodermal forces are crucial for invagination: the loss of apical constriction leads to a loss of the furrow, while the mesodermal radial shortening forces are the primary cause of the internalisation of the future mesoderm as the furrow rises. Ectodermal forces play a minor but significant role in furrow formation: without ectodermal forces the furrow is slower to form, does not close properly and has an aberrant morphology. Nevertheless, despite changes in the active mesodermal and ectodermal forces lead to changes in the timing and extent of furrow, invagination is eventually achieved in most cases, implying that the system is robust to perturbation and therefore over-determined
TrackSort: Predictive Tracking for Sorting Uncooperative Bulk Materials
Optical belt sorters are a versatile, state-of-the-art technology to sort bulk materials that are hard to sort based on only nonvisual properties. In this paper, we propose an extension to current optical belt sorters that involves replacing the line camera with an area camera to observe a wider field of view, allowing us to observe each particle over multiple time steps. By performing multitarget tracking, we are able to improve the prediction of each particle‘s movement and thus enhance the performance of the utilized separation mechanism. We show that our approach will allow belt sorters to handle new classes of bulk materials while improving cost efficiency. Furthermore, we lay out additional extensions that are made possible by our new paradig
Video Force Microscopy (VFM): A New Technique that Allows Cell-Level Driving Forces to Be Determined from Time-Lapse Images
A Thirty Kiloparsec Chain of "Beads on a String" Star Formation Between Two Merging Early Type Galaxies in the Core of a Strong-Lensing Galaxy Cluster
New Hubble Space Telescope ultraviolet and optical imaging of the
strong-lensing galaxy cluster SDSS J1531+3414 (z=0.335) reveals two centrally
dominant elliptical galaxies participating in an ongoing major merger. The
interaction is at least somewhat rich in cool gas, as the merger is associated
with a complex network of nineteen massive superclusters of young stars (or
small tidal dwarf galaxies) separated by ~1 kpc in projection from one another,
combining to an estimated total star formation rate of ~5 solar masses per
year. The resolved young stellar superclusters are threaded by narrow H-alpha,
[O II], and blue excess filaments arranged in a network spanning ~27 kpc across
the two merging galaxies. This morphology is strongly reminiscent of the
well-known "beads on a string" mode of star formation observed on kpc-scales in
the arms of spiral galaxies, resonance rings, and in tidal tails between
interacting galaxies. Nevertheless, the arrangement of this star formation
relative to the nuclei of the two galaxies is difficult to interpret in a
dynamical sense, as no known "beads on a string" systems associated with
kpc-scale tidal interactions exhibit such lopsided morphology relative to the
merger participants. In this Letter we present the images and follow-up
spectroscopy, and discuss possible physical interpretations for the unique
arrangement of the young stellar clusters. While we suggest that this
morphology is likely to be dynamically short-lived, a more quantitative
understanding awaits necessary multiwavelength follow-up, including optical
integral field spectroscopy, ALMA sub-mm interferometry, and Chandra X-ray
imaging.Comment: 7 pages, 4 figures, accepted for publication in ApJ Letters. High
resolution images of the cluster can be found at
http://hubblesite.org/news/2014/2
Weiterbildungsbedarfe zum Diversity Management mit Design Thinking definieren
Der Bedarf an Weiterbildungen zum Diversity Management wird durch Studien belegt. Um ihn für die im Rahmen des Projekts „Vielfalt als Chance“ geplante Weiterbildung zu definieren, wurde eine Marktanalyse bestehender Angebote durchgeführt und mit einer Analyse zu Potenzialen von Diversity Management aus explorativen Primärdatenerhebungen verknüpft, die marktrelevante Informationen zu möglichen Zielgruppen, Inhalten und Strukturen der geplanten Weiterbildung ermitteln konnte. Dabei ist in einem Co-Creation-Workshop mit Methoden des Design Thinkings eine kooperative Angebotsentwicklung mit externen Partner_innen durchgeführt worden, womit sichergestellt werden soll, dass sich die geplante Weiterbildung an der Nachfrage orientiert. Der Bericht stellt die Bedarfsanalyse und ihre Ergebnisse vor, wonach statt des ursprünglich geplanten Weiterbildungsmasters zum Diversity Management von den ins Auge gefassten Kund_innen Kontaktstudien zu Prozessgestaltung unter Bedingungen von Komplexität, Unsicherheit und Vielfalt bevorzugt würden, die bei Interesse zu einem DAS oder CAS kumulierbar sind
- …