2,696 research outputs found
Effects of grain shape on packing and dilatancy of sheared granular materials
Granular material exposed to shear shows a variety of unique phenomena:
Reynolds dilatancy, positional order and orientational order effects may
compete in the shear zone. We study granular packings consisting of macroscopic
prolate, oblate and spherical grains and compare their behaviour. X-ray
tomography is used to determine the particle positions and orientations in a
cylindrical split bottom shear cell. Packing densities and the arrangements of
individual particles in the shear zone are evaluated. For anisometric
particles, we observe the competition of two opposite effects. One the one
hand, the sheared granulate is dilated, but on the other hand the particles
reorient and align with respect to the streamlines. Even though aligned
cylinders in principle may achieve higher packing densities, this alignment
compensates for the effect of dilatancy only partially. The complex
rearrangements lead to a depression of the surface above the well oriented
region while neigbouring parts still show the effect of dilation in the form of
heaps. For grains with isotropic shapes, the surface remains rather flat.
Perfect monodisperse spheres crystallize in the shear zone, whereby positional
order partially overcompensates dilatancy effects. However, already slight
deviations from the ideal monodisperse sphere shape inhibit crystallization.Comment: 12 pages, 13 figures, accepted in Soft Matte
ΠΠΈΠ½Π΅ΡΠ°Π»ΠΎΠ³ΠΎ-ΠΏΠ΅ΡΡΠΎΡ ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΈ Π³Π΅ΠΎΡ ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΡΠ΅ΡΡΡ ΠΎΠΊΠΎΠ»ΠΎΡΡΠ΄Π½ΠΎΠ³ΠΎ ΠΌΠ΅ΡΠ°ΡΠΎΠΌΠ°ΡΠΈΠ·ΠΌΠ° Π² ΠΠ°ΠΏΠ°Π΄Π½ΠΎΠΌ Π·ΠΎΠ»ΠΎΡΠΎΡΡΠ΄Π½ΠΎΠΌ ΠΌΠ΅ΡΡΠΎΡΠΎΠΆΠ΄Π΅Π½ΠΈΠΈ (Π‘Π΅Π²Π΅ΡΠ½ΠΎΠ΅ ΠΠ°Π±Π°ΠΉΠΊΠ°Π»ΡΠ΅)
ΠΡΠΈΠ²Π΅Π΄Π΅Π½Ρ Π΄Π°Π½Π½ΡΠ΅ ΠΎΠ± ΡΡΠ»ΠΎΠ²ΠΈΡΡ
Π·Π°Π»Π΅Π³Π°Π½ΠΈΡ, ΠΌΠΎΡΡΠΎΠ»ΠΎΠ³ΠΈΠΈ ΡΡΠ΄Π½ΡΡ
ΡΠ΅Π», ΠΌΠΈΠ½Π΅ΡΠ°Π»ΡΠ½ΠΎΠΌ ΡΠΎΡΡΠ°Π²Π΅, ΡΠΈΠ·ΠΈΠΊΠΎ-Ρ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΈ ΡΠ΅ΡΠΌΠΎΠ΄ΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ΅ΠΆΠΈΠΌΠ°Ρ
ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ ΡΡΠ΄ ΠΠ°ΠΏΠ°Π΄Π½ΠΎΠ³ΠΎ Π·ΠΎΠ»ΠΎΡΠΎΡΡΠ΄Π½ΠΎΠ³ΠΎ ΠΌΠ΅ΡΡΠΎΡΠΎΠΆΠ΄Π΅Π½ΠΈΡ Π‘Π΅Π²Π΅ΡΠ½ΠΎΠ³ΠΎ ΠΠ°Π±Π°ΠΉΠΊΠ°Π»ΡΡ. ΠΠΏΠ΅ΡΠ²ΡΠ΅ ΠΏΠΎΠΊΠ°Π·Π°Π½Ρ ΠΏΠΎΡΡΠ΄ΠΎΠΊ ΠΌΠΈΠ½Π΅ΡΠ°Π»ΡΠ½ΠΎΠΉ Π·ΠΎΠ½Π°Π»ΡΠ½ΠΎΡΡΠΈ (ΡΡΡΡΠΊΡΡΡΠ°) ΠΈ ΠΌΠΈΠ½Π΅ΡΠ°Π»ΠΎΠ³ΠΎ-ΠΏΠ΅ΡΡΠΎΡ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΡΠ΅ΡΡΡ Π°ΠΏΠΎΠ΄ΠΎΠ»Π΅ΡΠΈΡΠΎΠ²ΡΡ
ΠΎΠΊΠΎΠ»ΠΎΠΆΠΈΠ»ΡΠ½ΡΡ
ΠΌΠ΅ΡΠ°ΡΠΎΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΎΡΠ΅ΠΎΠ»ΠΎΠ². ΠΠΎΠΊΠ°Π·ΡΠ²Π°Π΅ΡΡΡ ΠΏΡΠΈΠ½Π°Π΄Π»Π΅ΠΆΠ½ΠΎΡΡΡ ΠΏΠΎΡΠ»Π΅Π΄Π½ΠΈΡ
ΠΊ Π±Π΅ΡΠ΅Π·ΠΈΡΠΎΠ²ΠΎΠΉ ΠΌΠ΅ΡΠ°ΡΠΎΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠΎΡΠΌΠ°ΡΠΈΠΈ, Π° ΠΌΠ΅ΡΡΠΎΡΠΎΠΆΠ΄Π΅Π½ΠΈΡ - ΠΊ Π·ΠΎΠ»ΠΎΡΠΎΠΉ ΡΡΠ±ΡΠΎΡΠΌΠ°ΡΠΈΠΈ Π·ΠΎΠ»ΠΎΡΠΎ-ΡΡΠ°Π½-ΠΏΠΎΠ»ΠΈΠΌΠ΅ΡΠ°Π»Π»ΠΈΡΠ΅ΡΠΊΠΎΠΉ Π±Π΅ΡΠ΅Π·ΠΈΡΠΎΠ²ΠΎΠΉ ΡΡΠ΄Π½ΠΎΠΉ ΡΠΎΡΠΌΠ°ΡΠΈΠΈ. Π‘Π»Π°Π±ΠΎ ΠΊΠΎΠ½ΡΡΠ°ΡΡΠ½ΡΠ΅ Π°Π½ΠΎΠΌΠ°Π»ΠΈΠΈ Π·ΠΎΠ»ΠΎΡΠ°, ΡΠ΅ΡΠ΅Π±ΡΠ°, ΡΡΡΡΠΈ ΠΏΡΠΈΡΡΠΎΡΠ΅Π½Ρ ΠΊ ΡΡΠ»ΠΎΠ²ΡΠΌ Π·ΠΎΠ½Π°ΠΌ ΠΎΠΊΠΎΠ»ΠΎΠΆΠΈΠ»ΡΠ½ΡΡ
ΠΌΠ΅ΡΠ°ΡΠΎΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΎΡΠ΅ΠΎΠ»ΠΎΠ² Π² Π½Π΅ΠΏΠΎΡΡΠ΅Π΄ΡΡΠ²Π΅Π½Π½ΠΎΠΌ ΠΎΠ±ΡΠ°ΠΌΠ»Π΅Π½ΠΈΠΈ ΡΠ»Π°Π±ΠΎΠ·ΠΎΠ»ΠΎΡΠΎΠ½ΠΎΡΠ½ΡΡ
(ΠΏΠ΅ΡΠ²ΡΠ΅ Π³/Ρ) ΠΈΠ½ΡΠ΅ΡΠ²Π°Π»ΠΎΠ² ΠΊΠ²Π°ΡΡΠ΅Π²ΡΡ
ΠΆΠΈΠ». ΠΡΠ³ΡΠΌΠ΅Π½ΡΠΈΡΡΡΡΡΡ Π³Π΅Π½Π΅ΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΡΠ²ΡΠ·ΠΈ ΠΎΠΊΠΎΠ»ΠΎΠΆΠΈΠ»ΡΠ½ΡΡ
ΠΌΠ΅ΡΠ°ΡΠΎΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΈ Π³Π΅ΠΎΡ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΎΡΠ΅ΠΎΠ»ΠΎΠ² Ρ ΡΡΠ΄Π°ΠΌΠΈ ΠΈ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΠ΅ ΠΈΡ
Π² ΡΡΠ΄ΠΎΠΎΠ±ΡΠ°Π·ΡΡΡΠ΅ΠΌ ΠΏΡΠΎΡΠ΅ΡΡΠ΅ ΠΏΠΎΠ·Π΄Π½Π΅ΠΏΠ°Π»Π΅ΠΎΠ·ΠΎΠΉΡΠΊΠΎΠΉ ΠΌΠ΅ΡΠ°Π»Π»ΠΎΠ³Π΅Π½ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠΏΠΎΡ
ΠΈ. ΠΡΠ½ΠΎΠ²Π½ΡΠ΅ ΠΌΠΈΠ½Π΅ΡΠ°Π»ΠΎΠ³ΠΎ-ΠΏΠ΅ΡΡΠΎΡ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΈ Π³Π΅ΠΎΡ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΡΠ΅ΡΡΡ ΠΎΠΊΠΎΠ»ΠΎΠΆΠΈΠ»ΡΠ½ΠΎΠ³ΠΎ ΠΌΠ΅ΡΠ°ΡΠΎΠΌΠ°ΡΠΈΠ·ΠΌΠ° ΡΠ°ΡΡΠΌΠΎΡΡΠ΅Π½Ρ Π² ΡΡΠ°Π²Π½Π΅Π½ΠΈΠΈ Ρ ΡΠ°ΠΊΠΎΠ²ΡΠΌΠΈ Π΄ΡΡΠ³ΠΈΡ
ΠΌΠ΅ΡΡΠΎΡΠΎΠΆΠ΄Π΅Π½ΠΈΠΉ Π‘Π΅Π²Π΅ΡΠΎ-ΠΠ°Π±Π°ΠΉΠΊΠ°Π»ΡΡΠΊΠΎΠ³ΠΎ Π·ΠΎΠ»ΠΎΡΠΎΡΡΠ΄Π½ΠΎΠ³ΠΎ ΡΠ°ΠΉΠΎΠ½Π°
Evolution of shear zones in granular materials
The evolution of wide shear zones (or shear bands) was investigated
experimentally and numerically for quasistatic dry granular flows in split
bottom shear cells. We compare the behavior of materials consisting of beads,
irregular grains (e.g. sand) and elongated particles. Shearing an initially
random sample, the zone width was found to significantly decrease in the first
stage of the process. The characteristic shear strain associated with this
decrease is about unity and it is systematically increasing with shape
anisotropy, i.e. when the grain shape changes from spherical to irregular (e.g.
sand) and becomes elongated (pegs). The strongly decreasing tendency of the
zone width is followed by a slight increase which is more pronounced for rod
like particles than for grains with smaller shape anisotropy (beads or
irregular particles). The evolution of the zone width is connected to shear
induced density change and for nonspherical particles it also involves grain
reorientation effects. The final zone width is significantly smaller for
irregular grains than for spherical beads.Comment: 11 pages, 12 figures, submitted to Phys. Rev.
Expression of Human Immunodeficiency Virus Type 1 Gag Protein Precursor and Envelope Proteins from a Vesicular Stomatitis Virus Recombinant: High-Level Production of Virus-like Particles Containing HIV Envelope
AbstractRecombinant vesicular stomatitis viruses have been developed as high-level expression vectors which serve as effective vaccine vectors in animals (Roberts et al., 1998, J. Virol. 72, 4704β4711; Roberts et al., 1999, J. Virol. 73, 3723β3732). Here we show that two genes can be expressed simultaneously from a single, live-attenuated VSV recombinant. The genes used encode the Pr55gag protein precursor of HIV-1 (1.7-kb gene) and an HIV-1 envelope (Env) protein (2.4 kb gene). Our results show that VSV can accommodate up to a 40% increase in genome size with only a threefold reduction in virus titer. Recombinants expressing the Pr55gag protein precursor with or without Env protein produced abundant HIV virus-like particles (VLPs) in addition to bullet-shaped VSV particles. HIV Env protein expressed from a VSV recombinant also expressing Gag was specifically incorporated into the HIV VLPs but not into the VSV particles. In contrast, VSV G protein was found in both VSV particles and in HIV VLPs. Such VSV/HIV recombinants producing HIV VLPs with Env protein could be an effective source of HIV-like particles inducing both cellular and antibody-mediated immunity to HIV-1
The Metropolis and Evangelical Life: Coherence and Fragmentation in the βLost City of Londonβ
This article examines the interplay of different processes of cultural and subjective fragmentation experienced by conservative evangelical Anglicans, based on an ethnographic study of a congregation in central London. The author focuses on the evangelistic speaking practices of members of this church to explore how individuals negotiate contradictory norms of interaction as they move through different city spaces, and considers their response to tensions created by the demands of their workplace and their religious lives. Drawing on Georg Simmelβs βThe Metropolis and Mental Lifeβ, the author argues that their faith provides a sense of coherence and unity that responds to experiences of cultural fragmentation characteristic of everyday life in the city, while simultaneously leading to a specific consciousness of moral fragmentation that is inherent to conservative evangelicalism
Untersuchung der Praxistauglichkeit eines Ortungssystems zur Verbesserung des Herdenmanagements eines Milchviehbetriebes
Ziel dieses Versuches, der im Rahmen eines Praxisprojektes durchgefΓΌhrt wurde, war die ΓberprΓΌfung der Praxistauglichkeit des Real Time Location Systems (RTLS) Ubisense 7000 fΓΌr das Herdenmanagement. Neben der ΓberprΓΌfung der Genauigkeit der mit dem Ortungssystems erhobenen Daten, wurden Daten, zur AktivitΓ€tsmessung, Brunsterkennung, Aufenthaltsdauer in den Funktionsbereichen sowie Laufverhalten mithilfe von Pedometern und Videobeobachtung erfasst
Prospects for e-democracy in Europe
The drivers behind e-participation are digitalisation, the development of digital tools that can be usedfor citizen involvement β social media, deliberative software, e-voting systems, etc. β and growingaccess to the internet. In European countries, especially those that rank prominently among the top 50performers, citizens have more and more opportunities to have their say in government and politics.According to the UN, the largest share of e-participation initiatives relates to central and localgovernments giving access to public sector information and public consultation via digital tools.Recently there has been a growing focus on citizen involvement in policy making, although progressin this field has been modest so far
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