78 research outputs found
Influence of ring frame process parameters on yarn structure and fabric assistance
An attempt has been made to study the influence of ring frame parameters i.e. yarn twist multiplies, spindle speed and ring frame draft on yarn characteristics to exploit the translation of yarn structures into the fabric assistance. Understanding the relationship between yarn structure and fabric strength helps in engineering the yarn structure to improve the strength translation of yarns to fabric strength. Accordingly, study on fabric strength in weft/warp direction per yarn, weft/ warp break force inside fabric, weft/warp pull-out force and yarn failure zone length are also carried out. Yarn structure is found to affect the fabric thickness and fabric tensile behaviour. The yarn diameter has a direct effect on the yarn pull out force. The yarn structure also plays a dominant role in deciding the yarn failure zone length
Multiflagellarity leads to the size-independent swimming speed of bacteria
Flagella are essential organelles of bacteria enabling their swimming
motility. While monotrichous or uniflagellar bacteria possess a single
flagellum at one pole of their body, peritrichous bacteria grow multiple
flagella over the body surface, which form a rotating helical bundle propelling
the bacteria forward. Although the adaptation of bacterial cellular features is
under strong evolutionary pressure, existing evidence suggests that
multiflagellarity confers no noticeable benefit to the swimming of peritrichous
bacteria in bulk fluids compared with uniflagellar bacteria. This puzzling
result poses a long-standing question: why does multiflagellarity emerge given
the high metabolic cost of flagellar synthesis? Contrary to the prevailing
wisdom that its benefit lies beyond the basic function of flagella in steady
swimming, here we show that multiflagellarity provides a significant selective
advantage to bacteria in terms of their swimming ability, allowing bacteria to
maintain a constant swimming speed over a wide range of body size. By
synergizing experiments of immense sample sizes with quantitative hydrodynamic
modeling and simulations, we reveal how bacteria utilize the increasing number
of flagella to regulate the flagellar motor load, which leads to faster
flagellar rotation neutralizing the higher fluid drag on their larger bodies.
Without such a precise balancing mechanism, the swimming speed of uniflagellar
bacteria generically decreases with increasing body size. Our study sheds light
on the origin of multiflagellarity, a ubiquitous cellular feature of bacteria.
The uncovered difference between uniflagellar and multiflagellar swimming is
important for understanding environmental influence on bacterial morphology and
useful for designing artificial flagellated microswimmers.Comment: 23 pages, 4 figure
Phase dependent view of Cyclotron lines from model accretion mounds on Neutron Stars
In this paper we make a phase dependent study of the effect of the distortion
of local magnetic field due to confinement of accreted matter in X-ray pulsars
on the cyclotron spectra emitted from the hotspot . We have numerically solved
the Grad-Shafranov equation for axisymmetric static MHD equilibria of matter
confined at the polar cap of neutron stars. From our solution we model the
cyclotron spectra that will be emitted from the region, using a simple
prescription and integrating over the entire mound. Radiative transfer through
the accretion column overlying the mound may significantly modify the spectra
in comparison to those presented here. However we ignore this in the present
paper in order to expose the effects directly attributable to the mound itself.
We perform a spin phase dependent analysis of the spectra to study the effect
of the viewing geometry.Comment: 13 pages, 19 figure
Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A
Horizon-scale images of black holes (BHs) and their shadows have opened an
unprecedented window onto tests of gravity and fundamental physics in the
strong-field regime. We consider a wide range of well-motivated deviations from
classical General Relativity (GR) BH solutions, and constrain them using the
Event Horizon Telescope (EHT) observations of Sagittarius A (Sgr A),
connecting the size of the bright ring of emission to that of the underlying BH
shadow and exploiting high-precision measurements of Sgr A's
mass-to-distance ratio. The scenarios we consider, and whose fundamental
parameters we constrain, include various regular BHs, string-inspired
space-times, violations of the no-hair theorem driven by additional fields,
alternative theories of gravity, novel fundamental physics frameworks, and BH
mimickers including well-motivated wormhole and naked singularity space-times.
We demonstrate that the EHT image of Sgr A places particularly stringent
constraints on models predicting a shadow size larger than that of a
Schwarzschild BH of a given mass, with the resulting limits in some cases
surpassing cosmological ones. Our results are among the first tests of
fundamental physics from the shadow of Sgr A and, while the latter appears
to be in excellent agreement with the predictions of GR, we have shown that a
number of well motivated alternative scenarios, including BH mimickers, are far
from being ruled out at present.Comment: 82 pages, 47 figures, 50+ models tested. v3: fixed a few figures,
clarified several points, included various analytical expressions for shadow
sizes within the different models, added a few references, included a summary
table (Table II). Version accepted for publication in Classical and Quantum
Gravit
Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC
Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe
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