3,754 research outputs found
Review of the book \u3ci\u3eThe Chinese Worker After Socialism\u3c/i\u3e
In The Chinese Worker after Socialism, William Hurst employs subnational comparison to explain different outcomes for workers in the process of reform of state-owned industry in China. In particular, Hurst provides in-depth analysis of regional variation of the sequencing and volume of layoffs, how the local state attempted to handle unemployment, actual outcomes in re-employment, and the dynamics of worker protest. By taking subnational regions as the unit of analysis, we see that the process of smashing the iron rice bowl has not been a unified and coherent project but rather one that has been messy, uneven, and subject to great variation in timing and outcomes. This variation is explained by differences in the political economy of each region
China Since Tiananmen: The Labor Movement
[Excerpt] The twenty years since 1989 have brought two major developments in worker activism. First, whereas workers were part of the mass uprising in the Tiananmen movement, albeit as subordinate partners to the students, labor activism since then has been almost entirely confined to the working class. While the ranks of aggrieved workers have proliferated (expanding from workers in the state-owned sector to include migrant workers) and the forms and incidents of labor activism have multiplied, there is hardly any sign of mobilization that transcends class or regional lines.
Second, we observe that a long-term decline in worker power at the point of production – power that was previously institutionalized in skill hierarchies, union representation, democratic management, permanent or long-term employment, and other conditions of service constitutive of the socialist social contract - is going on even as workers gain more power (at least on paper) outside the workplace. New labor laws have broadened workers\u27 rights and expanded administrative and judicial channels for resolving labor conflicts. These legal and bureaucratic procedures have atomized and depoliticized labor activism even as they have engendered and intensified mobilization outside official limits
Light Trapping Textures Designed by Electromagnetic Optimization for Sub-Wavelength Thick Solar Cells
Light trapping in solar cells allows for increased current and voltage, as
well as reduced materials cost. It is known that in geometrical optics, a
maximum 4n^2 absorption enhancement factor can be achieved by randomly
texturing the surface of the solar cell, where n is the material refractive
index. This ray-optics absorption enhancement limit only holds when the
thickness of the solar cell is much greater than the optical wavelength. In
sub-wavelength thin films, the fundamental questions remain unanswered: (1)
what is the sub-wavelength absorption enhancement limit and (2) what surface
texture realizes this optimal absorption enhancement? We turn to computational
electromagnetic optimization in order to design nanoscale textures for light
trapping in sub-wavelength thin films. For high-index thin films, in the weakly
absorbing limit, our optimized surface textures yield an angle- and
frequency-averaged enhancement factor ~39. They perform roughly 30% better than
randomly textured structures, but they fall short of the ray optics enhancement
limit of 4n^2 ~ 50
Results From Core-Collapse Simulations with Multi-Dimensional, Multi-Angle Neutrino Transport
We present new results from the only 2D multi-group, multi-angle calculations
of core-collapse supernova evolution. The first set of results from these
calculations was published in Ott et al. (2008). We have followed a nonrotating
and a rapidly rotating 20 solar mass model for ~400 ms after bounce. We show
that the radiation fields vary much less with angle than the matter quantities
in the region of net neutrino heating. This obtains because most neutrinos are
emitted from inner radiative regions and because the specific intensity is an
integral over sources from many angles at depth. The latter effect can only be
captured by multi-angle transport. We then compute the phase relationship
between dipolar oscillations in the shock radius and in matter and radiation
quantities throughout the postshock region. We demonstrate a connection between
variations in neutrino flux and the hydrodynamical shock oscillations, and use
a variant of the Rayleigh test to estimate the detectability of these neutrino
fluctuations in IceCube and Super-K. Neglecting flavor oscillations,
fluctuations in our nonrotating model would be detectable to ~10 kpc in
IceCube, and a detailed power spectrum could be measured out to ~5 kpc. These
distances are considerably lower in our rapidly rotating model or with
significant flavor oscillations. Finally, we measure the impact of rapid
rotation on detectable neutrino signals. Our rapidly rotating model has strong,
species-dependent asymmetries in both its peak neutrino flux and its light
curves. The peak flux and decline rate show pole-equator ratios of up to ~3 and
~2, respectively.Comment: 13 pages, 9 figures, ApJ accepted. Replaced with accepted versio
Juvenile rank acquisition is associated with fitness independent of adult rank
Social rank is a significant determinant of fitness in a variety of species. The importance of social rank suggests that the process by which juveniles come to establish their position in the social hierarchy is a critical component of development. Here, we use the highly predictable process of rank acquisition in spotted hyenas to study the consequences of variation in rank acquisition in early life. In spotted hyenas, rank is ‘inherited’ through a learning process called ‘maternal rank inheritance.’ This pattern is very consistent: approximately 80% of juveniles acquire the exact rank expected under the rules of maternal rank inheritance. The predictable nature of rank acquisition in these societies allows the process of rank acquisition to be studied independently from the ultimate rank that each juvenile attains. In this study, we use Elo-deviance scores, a novel application of the Elo-rating method, to calculate each juvenile’s deviation from the expected pattern of maternal rank inheritance during development. Despite variability in rank acquisition among juveniles, most of these juveniles come to attain the exact rank expected of them according to the rules of maternal rank inheritance. Nevertheless, we find that transient variation in rank acquisition in early life is associated with long-term fitness consequences for these individuals: juveniles ‘underperforming’ their expected ranks show reduced survival and lower lifetime reproductive success than better-performing peers, and this relationship is independent of both maternal rank and rank achieved in adulthood. We also find that multiple sources of early life adversity have cumulative, but not compounding, effects on fitness. Future work is needed to determine if variation in rank acquisition directly affects fitness, or if some other variable, such as maternal investment or juvenile condition, causes variation in both of these outcomes.
(Includes Supplemental Materials and Reviewers\u27 Comments.
Dynamic allometry in coastal overwash morphology
Allometry refers to a physical principle in which geometric (and/or metabolic) characteristics of an object or organism are correlated to its size. Allometric scaling relationships typically manifest as power laws. In geomorphic contexts, scaling relationships are a quantitative signature of organization, structure, or regularity in a landscape, even if the mechanistic processes responsible for creating such a pattern are unclear. Despite the ubiquity and variety of scaling relationships in physical landscapes, the emergence and development of these relationships tend to be difficult to observe - either because the spatial and/or temporal scales over which they evolve are so great or because the conditions that drive them are so dangerous (e.g. an extreme hazard event). Here, we use a physical experiment to examine dynamic allometry in overwash morphology along a model coastal barrier. We document the emergence of a canonical scaling law for length versus area in overwash deposits (washover). Comparing the experimental features, formed during a single forcing event, to 5 decades of change in real washover morphology from the Ria Formosa barrier system, in southern Portugal, we find differences between patterns of morphometric change at the event scale versus longer timescales. Our results may help inform and test process-based coastal morphodynamic models, which typically use statistical distributions and scaling laws to underpin empirical or semi-empirical parameters at fundamental levels of model architecture. More broadly, this work dovetails with theory for landscape evolution more commonly associated with fluvial and alluvial terrain, offering new evidence from a coastal setting that a landscape may reflect characteristics associated with an equilibrium or steady-state condition even when features within that landscape do not.Funding Agency
NERC Natural Environment Research Council
NE/N015665/2
Leverhulme Trust
RPG-2018-282info:eu-repo/semantics/publishedVersio
Destruction of Interstellar Dust in Evolving Supernova Remnant Shock Waves
Supernova generated shock waves are responsible for most of the destruction
of dust grains in the interstellar medium (ISM). Calculations of the dust
destruction timescale have so far been carried out using plane parallel steady
shocks, however that approximation breaks down when the destruction timescale
becomes longer than that for the evolution of the supernova remnant (SNR)
shock. In this paper we present new calculations of grain destruction in
evolving, radiative SNRs. To facilitate comparison with the previous study by
Jones et al. (1996), we adopt the same dust properties as in that paper. We
find that the efficiencies of grain destruction are most divergent from those
for a steady shock when the thermal history of a shocked gas parcel in the SNR
differs significantly from that behind a steady shock. This occurs in shocks
with velocities >~ 200 km/s for which the remnant is just beginning to go
radiative. Assuming SNRs evolve in a warm phase dominated ISM, we find dust
destruction timescales are increased by a factor of ~2 compared to those of
Jones et al. (1996), who assumed a hot gas dominated ISM. Recent estimates of
supernova rates and ISM mass lead to another factor of ~3 increase in the
destruction timescales, resulting in a silicate grain destruction timescale of
~2-3 Gyr. These increases, while not able resolve the problem of the discrepant
timescales for silicate grain destruction and creation, are an important step
towards understanding the origin, and evolution of dust in the ISM.Comment: 30 pages, 8 figures, accepted for publication in the Astrophysical
Journa
Localization of gauge fields in a tachyonic de Sitter thick braneworld
In this work we show that universal gauge vector fields can be localized on
the recently proposed 5D thick tachyonic braneworld which involves a de Sitter
cosmological background induced on the 3-brane. Namely, by performing a
suitable decomposition of the vector field, the resulting 4D effective action
corresponds to a massive gauge field, while the profile along the extra
dimension obeys a Schroedinger-like equation with a Poeschl-Teller potential.
It turns out that the massless zero mode of the gauge field is bound to the
expanding 3-brane and allows us to recover the standard 4D electromagnetic
phenomena of our world. Moreover, this zero mode is separated from the
continuum of Kaluza-Klein (KK) modes by a mass gap determined by the scale of
the expansion parameter. We also were able to analytically solve the
corresponding Schroedinger-like equation for arbitrary mass, showing that KK
massive modes asymptotically behave like plane waves as expected.Comment: 7 pages in latex, no figure
Multi-Dimensional Explorations in Supernova Theory
In this paper, we bring together various of our published and unpublished
findings from our recent 2D multi-group, flux-limited radiation hydrodynamic
simulations of the collapse and explosion of the cores of massive stars. Aided
by 2D and 3D graphical renditions, we motivate the acoustic mechanism of
core-collapse supernova explosions and explain, as best we currently can, the
phases and phenomena that attend this mechanism. Two major foci of our
presentation are the outer shock instability and the inner core g-mode
oscillations. The former sets the stage for the latter, which damp by the
generation of sound. This sound propagates outward to energize the explosion
and is relevant only if the core has not exploded earlier by some other means.
Hence, it is a more delayed mechanism than the traditional neutrino mechanism
that has been studied for the last twenty years since it was championed by
Bethe and Wilson. We discuss protoneutron star convection,
accretion-induced-collapse, gravitational wave emissions, pulsar kicks, the
angular anisotropy of the neutrino emissions, a subset of numerical issues, and
a new code we are designing that should supercede our current supernova code
VULCAN/2D. Whatever ideas last from this current generation of numerical
results, and whatever the eventual mechanism(s), we conclude that the breaking
of spherical symmetry will survive as one of the crucial keys to the supernova
puzzle.Comment: To be published in the "Centennial Festschrift for Hans Bethe,"
Physics Reports (Elsevier: Holland), ed. G.E. Brown, E. van den Heuvel, and
V. Kalogera, 200
Type II-Plateau supernova radiation: dependencies on progenitor and explosion properties
We explore the properties of Type II-Plateau (II-P) supernovae (SNe) together
with their red-supergiant (RSG) star progenitors. Using MESA STAR, we modulate
the parameters (e.g., mixing length, overshoot, rotation, metallicity) that
control the evolution of a 15Msun main-sequence star to produce a variety of
physical pre-SN models and SN II-P ejecta. We extend previous modeling of SN
II-P radiation to include photospheric and nebular phases, as well as
multi-band light curves and spectra. Our treatment does not assume local
thermodynamic equilibrium, is time dependent, treats explicitly the effects of
line blanketing, and incorporates non-thermal processes. We find that the color
properties of SNe II-P require large model atoms for FeI and FeII, much larger
than adopted in Dessart & Hillier (2011). The color properties also imply RSG
progenitors of limited extent (~500Rsun) --- larger progenitor stars produce a
SN II-P radiation that remains too blue for too long. This finding calls for a
reduction of RSG radii, perhaps through a strengthening of convective energy
transport in RSG envelopes. Increased overshoot and rotation reduce the ratio
of ejecta to helium-core mass, similarly to an increase in main-sequence mass,
and thus complicate the inference ofprogenitor masses. In contrast to the great
sensitivity on progenitor radius, SN II-P color evolution appears insensitive
to variations in explosion energy. Finally, we document the numerous SN II-P
signatures that vary with progenitor metallicity, revealing their potential for
metallicity determinations in the nearby and distant Universe.Comment: Paper accepted to MNRA
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