900 research outputs found
South Korea's automotive labour regime, Hyundai Motorsβ global production network and tradeβbased integration with the European Union
This article explores the interrelationship between global production networks(GPNs) and free trade agreements (FTAs) in the South Korean auto industry and its employment relations. It focuses on the production network of the Hyundai Motor Group (HMG) β the third biggest automobile manufacturer in the world β and the FTA between the EU and South Korea. This was the first of the EUβs βnew generationβ FTAs, which among other things contained provisions designed to protect and promote labour standards. The articleβs argument is twofold. First, that HMGβs production network and Koreaβs political economy (of which HMG is a crucial part) limited the possibilities for the FTAβs labour provisions to take effect. Second, that the commercial provisions in this same FTA simultaneously eroded HMGβs domestic market and corporate profitability, leading to adverse consequences for auto workers in the more
insecure and low-paid jobs. In making this argument, the article advances a multiscalar conceptualization of the labour regime as an analytical intermediary between GPNs and FTAs. It also provides one of the first empirical studies of the EUβSouth Korea FTA in terms of employment relations, drawing on 105 interviews with trade unions, employer associations, automobile companies and state officials across both parties
Stable isotope analysis provides new information on winter habitat use of declining avian migrants that is relevant to their conservation
Winter habitat use and the magnitude of migratory connectivity are important parameters when assessing drivers of the marked declines in avian migrants. Such information is unavailable for most species. We use a stable isotope approach to assess these factors for three declining African-Eurasian migrants whose winter ecology is poorly known: wood warbler Phylloscopus sibilatrix, house martin Delichon urbicum and common swift Apus apus. Spatially segregated breeding wood warbler populations (sampled across a 800 km transect), house martins and common swifts (sampled across a 3,500 km transect) exhibited statistically identical intra-specific carbon and nitrogen isotope ratios in winter grown feathers. Such patterns are compatible with a high degree of migratory connectivity, but could arise if species use isotopically similar resources at different locations. Wood warbler carbon isotope ratios are more depleted than typical for African-Eurasian migrants and are compatible with use of moist lowland forest. The very limited variance in these ratios indicates specialisation on isotopically restricted resources, which may drive the similarity in wood warbler populations' stable isotope ratios and increase susceptibility to environmental change within its wintering grounds. House martins were previously considered to primarily use moist montane forest during the winter, but this seems unlikely given the enriched nature of their carbon isotope ratios. House martins use a narrower isotopic range of resources than the common swift, indicative of increased specialisation or a relatively limited wintering range; both factors could increase house martins' vulnerability to environmental change. The marked variance in isotope ratios within each common swift population contributes to the lack of population specific signatures and indicates that the species is less vulnerable to environmental change in sub-Saharan Africa than our other focal species. Our findings demonstrate how stable isotope research can contribute to understanding avian migrants' winter ecology and conservation status
Optically guided mode study of nematic liquid crystal alignment on a zero-order grating
B. T. Hallam and J. Roy Sambles, Physical Review E, Vol. 61, pp. 6699-6704 (2000). "Copyright Β© 2000 by the American Physical Society."The characterization of a liquid crystal cell, which comprises one zero-order (that is, at the wavelength of study it is nondiffractive) diffraction grating and one rubbed polyimide-coated substrate, has been performed using an optically guided mode technique. The cell is filled with nematic liquid crystal E7 (manufactured and sold by Merck, Poole, U.K.). The excitation of fully leaky guided modes within the liquid crystal layer has allowed the optical director profile to be quantified under the application of weak in-plane electric fields. The fitting of angle-dependent optical data to multilayer optical theory yields the accurate twist profile of the liquid crystal for different field strengths. Comparisons with profiles predicted from elastic continuum theory, assuming a Rapini-Papoular-type anchoring at the surfaces, allow both the azimuthal anchoring strength at each surface and the twist elastic constant of the bulk to be accurately determined. Repeating these measurements as a function of temperature allows the surface and bulk order parameters of the grating-aligned liquid crystal to be deduced
Photometric study of the late-time near-infrared plateau in Type Ia supernovae
We present an in-depth study of the late-time near-infrared plateau in Type
Ia supernovae (SNe Ia), which occurs between 70-500 d. We double the existing
sample of SNe Ia observed during the late-time near-infrared plateau with new
observations taken with the Hubble Space Telescope, Gemini, New Technology
Telescope, the 3.5m Calar Alto Telescope, and the Nordic Optical Telescope. Our
sample consists of 24 nearby SNe Ia at redshift < 0.025. We are able to confirm
that no plateau exists in the Ks band for most normal SNe Ia. SNe Ia with
broader optical light curves at peak tend to have a higher average brightness
on the plateau in J and H, most likely due to a shallower decline in the
preceding 100 d. SNe Ia that are more luminous at peak also show a steeper
decline during the plateau phase in H. We compare our data to state-of-the-art
radiative transfer models of nebular SNe Ia in the near-infrared. We find good
agreement with the sub-Mch model that has reduced non-thermal ionisation rates,
but no physical justification for reducing these rates has yet been proposed.
An analysis of the spectral evolution during the plateau demonstrates that the
ratio of [Fe II] to [Fe III] contribution in a near-infrared filter determines
the light curve evolution in said filter. We find that overluminous SNe decline
slower during the plateau than expected from the trend seen for normal SNe IaComment: 17 pages, 8 figures, Accepted for publication in MNRA
Neuronal activity in medial superior temporal area (MST) during memory-based smooth pursuit eye movements in monkeys
We examined recently neuronal substrates for predictive pursuit using a memory-based smooth pursuit task that distinguishes the discharge related to memory of visual motion-direction from that related to movement preparation. We found that the supplementary eye fields (SEF) contain separate signals coding memory and assessment of visual motion-direction, decision not-to-pursue, and preparation for pursuit. Since medial superior temporal area (MST) is essential for visual motion processing and projects to SEF, we examined whether MST carried similar signals. We analyzed the discharge of 108 MSTd neurons responding to visual motion stimuli. The majority (69/108Β =Β 64%) were also modulated during smooth pursuit. However, in nearly all (104/108Β =Β 96%) of the MSTd neurons tested, there was no significant discharge modulation during the delay periods that required memory of visual motion-direction or preparation for smooth pursuit or not-to-pursue. Only 4 neurons of the 108 (4%) exhibited significantly higher discharge rates during the delay periods; however, their responses were non-directional and not instruction specific. Representative signals in the MSTd clearly differed from those in the SEF during memory-based smooth pursuit. MSTd neurons are unlikely to provide signals for memory of visual motion-direction or preparation for smooth pursuit eye movements
Integration of Sensory and Reward Information during Perceptual Decision-Making in Lateral Intraparietal Cortex (LIP) of the Macaque Monkey
Single neurons in cortical area LIP are known to carry information relevant to both sensory and value-based decisions that are reported by eye movements. It is not known, however, how sensory and value information are combined in LIP when individual decisions must be based on a combination of these variables. To investigate this issue, we conducted behavioral and electrophysiological experiments in rhesus monkeys during performance of a two-alternative, forced-choice discrimination of motion direction (sensory component). Monkeys reported each decision by making an eye movement to one of two visual targets associated with the two possible directions of motion. We introduced choice biases to the monkeys' decision process (value component) by randomly interleaving balanced reward conditions (equal reward value for the two choices) with unbalanced conditions (one alternative worth twice as much as the other). The monkeys' behavior, as well as that of most LIP neurons, reflected the influence of all relevant variables: the strength of the sensory information, the value of the target in the neuron's response field, and the value of the target outside the response field. Overall, detailed analysis and computer simulation reveal that our data are consistent with a two-stage drift diffusion model proposed by Diederich and Bussmeyer [1] for the effect of payoffs in the context of sensory discrimination tasks. Initial processing of payoff information strongly influences the starting point for the accumulation of sensory evidence, while exerting little if any effect on the rate of accumulation of sensory evidence
SN 2022jli: a type Ic supernova with periodic modulation of its light curve and an unusually long rise
We present multi-wavelength photometry and spectroscopy of SN 2022jli, an
unprecedented Type Ic supernova discovered in the galaxy NGC 157 at a distance
of 23 Mpc. The multi-band light curves reveal many remarkable
characteristics. Peaking at a magnitude of , the high-cadence
photometry reveals 12.5day periodic undulations superimposed on the
200 day supernova decline. This periodicity is observed in the light curves
from nine separate filter and instrument configurations with peak-to-peak
amplitudes of 0.1 mag. This is the first time that repeated periodic
oscillations, over many cycles, have been detected in a supernova light curve.
SN 2022jli also displays an extreme early excess which fades over 25
days followed by a rise to a peak luminosity of erg
s. Although the exact explosion epoch is not constrained by data, the
time from explosion to maximum light is 59 days. The luminosity can
be explained by a large ejecta mass (M)
powered by Ni but we find difficulty in quantitatively modelling the
early excess with circumstellar interaction and cooling. Collision between the
supernova ejecta and a binary companion is a possible source of this emission.
We discuss the origin of the periodic variability in the light curve, including
interaction of the SN ejecta with nested shells of circumstellar matter and
neutron stars colliding with binary companions.Comment: Accepted in ApJ
Can Monkeys Choose Optimally When Faced with Noisy Stimuli and Unequal Rewards?
We review the leaky competing accumulator model for two-alternative forced-choice decisions with cued responses, and propose extensions to account for the influence of unequal rewards. Assuming that stimulus information is integrated until the cue to respond arrives and that firing rates of stimulus-selective neurons remain well within physiological bounds, the model reduces to an Ornstein-Uhlenbeck (OU) process that yields explicit expressions for the psychometric function that describes accuracy. From these we compute strategies that optimize the rewards expected over blocks of trials administered with mixed difficulty and reward contingencies. The psychometric function is characterized by two parameters: its midpoint slope, which quantifies a subject's ability to extract signal from noise, and its shift, which measures the bias applied to account for unequal rewards. We fit these to data from two monkeys performing the moving dots task with mixed coherences and reward schedules. We find that their behaviors averaged over multiple sessions are close to optimal, with shifts erring in the direction of smaller penalties. We propose two methods for biasing the OU process to produce such shifts
Influence of riboflavin on the reduction of radionuclides by Shewanella oneidenis MR-1
Uranium (as UO22+), technetium (as TcO4β) and neptunium (as NpO2+) are highly mobile radionuclides that can be reduced enzymatically by a range of anaerobic and facultatively anaerobic microorganisms, including Shewanella oneidensis MR-1, to poorly soluble species. The redox chemistry of Pu is more complicated, but the dominant oxidation state in most environments is highly insoluble Pu(IV), which can be reduced to Pu(III) which has a potentially increased solubility which could enhance migration of Pu in the environment. Recently it was shown that flavins (riboflavin and flavin mononucleotide (FMN)) secreted by Shewanella oneidensis MR-1 can act as electron shuttles, promoting anoxic growth coupled to the accelerated reduction of poorly-crystalline Fe(III) oxides. Here, we studied the role of riboflavin in mediating the reduction of radionuclides in cultures of Shewanella oneidensis MR-1. Our results demonstrate that the addition of 10 ΞΌM riboflavin enhances the reduction rate of Tc(VII) to Tc(IV), Pu(IV) to Pu(III) and to a lesser extent, Np(V) to Np(IV), but has no significant influence on the reduction rate of U(VI) by Shewanella oneidensis MR-1. Thus riboflavin can act as an extracellular electron shuttle to enhance rates of Tc(VII), Np(V) and Pu(IV) reduction, and may therefore play a role in controlling the oxidation state of key redox active actinides and fission products in natural and engineered environments. These results also suggest that the addition of riboflavin could be used to accelerate the bioremediation of radionuclide-contaminated environments
- β¦