6,971 research outputs found
Exploring the functional domain and the target of the tetanus toxin light chain in neurohypophysial terminals
The tetanus toxin light chain blocks calcium induced vasopressin release from neurohypophysial nerve terminals. Here we show that histidine residue 233 within the putative zinc binding motif of the tetanus toxin light chain is essential for the inhibition of exocytosis, in the rat. The zinc chelating agent dipicolinic acid as well as captopril, an inhibitor of zinc-dependent peptidases, counteract the effect of the neurotoxin. Synthetic peptides, the sequences of which correspond to motifs present in the cytoplasmic domain of the synaptic vesicle membrane protein synaptobrevin 1 and 2, prevent the effect of the tetanus toxin light chain.
Our results indicate that zinc bound to the zinc binding motif constitutes the active site of the tetanus toxin light chain. Moreover they suggest that cleavage of synaptobrevin by the neurotoxin causes the inhibition of exocytotic release of vasopressin from secretory granules
Next Generation Cosmology: Constraints from the Euclid Galaxy Cluster Survey
We study the characteristics of the galaxy cluster samples expected from the
European Space Agency's Euclid satellite and forecast constraints on
cosmological parameters describing a variety of cosmological models. The method
used in this paper, based on the Fisher Matrix approach, is the same one used
to provide the constraints presented in the Euclid Red Book (Laureijs et
al.2011). We describe the analytical approach to compute the selection function
of the photometric and spectroscopic cluster surveys. Based on the photometric
selection function, we forecast the constraints on a number of cosmological
parameter sets corresponding to different extensions of the standard LambdaCDM
model. The dynamical evolution of dark energy will be constrained to Delta
w_0=0.03 and Delta w_a=0.2 with free curvature Omega_k, resulting in a
(w_0,w_a) Figure of Merit (FoM) of 291. Including the Planck CMB covariance
matrix improves the constraints to Delta w_0=0.02, Delta w_a=0.07 and a
FoM=802. The amplitude of primordial non-Gaussianity, parametrised by f_NL,
will be constrained to \Delta f_NL ~ 6.6 for the local shape scenario, from
Euclid clusters alone. Using only Euclid clusters, the growth factor parameter
\gamma, which signals deviations from GR, will be constrained to Delta
\gamma=0.02, and the neutrino density parameter to Delta Omega_\nu=0.0013 (or
Delta \sum m_\nu=0.01). We emphasise that knowledge of the observable--mass
scaling relation will be crucial to constrain cosmological parameters from a
cluster catalogue. The Euclid mission will have a clear advantage in this
respect, thanks to its imaging and spectroscopic capabilities that will enable
internal mass calibration from weak lensing and the dynamics of cluster
galaxies. This information will be further complemented by wide-area
multi-wavelength external cluster surveys that will already be available when
Euclid flies. [Abridged]Comment: submitted to MNRA
Discrimination, labour markets and the Labour Market Prospects of Older Workers: What Can a Legal Case Teach us?
As governments become increasingly concerned about the fiscal implications of the ageing population, labour market policies have sought to encourage mature workers to remain in the labour force. The âhuman capitalâ discourses motivating these policies rest on the assumption that older workers armed with motivation and vocational skills will be able to return to fulfilling work. This paper uses the post-redundancy recruitment experiences of former Ansett Airlines
flight attendants to develop a critique of these expectations. It suggests that policies to increase
older workersâ labour market participation will not succeed while persistent socially constructed age- and gender- typing shape labour demand. The conclusion argues for policies sensitive to the institutional structures that shape employer preferences, the competitive rationality of
discriminatory practices, and the irresolvable tension between workersâ human rights and employersâ property rights
Opportunities for future supernova studies of cosmic acceleration
We investigate the potential of a future supernova dataset, as might be
obtained by the proposed SNAP satellite, to discriminate among different ``dark
energy'' theories that describe an accelerating Universe. We find that many
such models can be distinguished with a fit to the effective
pressure-to-density ratio, , of this energy. More models can be
distinguished when the effective slope, , of a changing is also fit,
but only if our knowledge of the current mass density, , is improved.
We investigate the use of ``fitting functions'' to interpret luminosity
distance data from supernova searches, and argue in favor of a particular
preferred method, which we use in our analysis.Comment: Four pages including figures. Final published version. No significant
changes from v
Crystal growth, structural studies and superconducting properties of beta-pyrochlore KOs2O6
Single crystals of KOs2O6 have been grown in a sealed quartz ampoule.
Detailed single crystal X-ray diffraction studies at room temperature show
Bragg peaks that violate Fd-3m symmetry. With a comparative structure
refinement the structure is identified as non-centrosymmetric (F-43m). Compared
to the ideal beta-pyrochlore lattice (Fd-3m), both Os tetrahedral and O
octahedral network exhibit breathing mode like volume changes accompanied by
strong anisotropic character of the K channels. The crystals show metallic
conductivity and a sharp transition to the superconducting state at Tc = 9.65
K. Superconducting properties have been investigated by magnetization
measurements performed in a temperature range from 2 to 12 K and in magnetic
fields from 0 to 60 kOe. The temperature dependence of the upper critical field
Hc2(T) has been determined and the initial slope (dHc2/dT)Tc = -33.3 kOe/K has
been obtained near Tc. The upper critical field at zero temperature was
estimated to be Hc2(0) \cong 230 kOe, which is a value close to the Pauli
paramagnetic limiting field Hp(0)\cong 250 kOe. Then, the Ginzburg-Landau (GL)
coherence length xi GL(0) \approx 3.8 nm was calculated, and the Maki parameter
alpha \approx \sqrt 2 was obtained, suggesting the possibility that KOs2O6
might behave unconventionally at low temperatures and high magnetic fields
Regulating Clothing Outwork: A Sceptic's View
By applying the strategies of international anti-sweatshop campaigns to the Australian context, recent regulations governing home-based clothing production hold retailers
responsible for policing the wages and employment conditions of clothing outworkers who manufacture clothing on their behalf. This paper argues that the new approach
oversimplifies the regulatory challenge by assuming (1) that Australian clothing production is organised in a hierarchical âbuyer-ledâ linear structure in which core
retail firms have the capacity to control their suppliersâ behaviour; (2) that firms act as unitary moral agents; and (3) that interventions imported from other times and places
are applicable to the contemporary Australian context. After considering some alternative regulatory approaches, the paper concludes that the new regulatory strategy effectively privatises responsibility for labour market conditions â a development that cries out for further debate
Are Labour Markets Necessarily Local? Spatiality, Segmentation and Scale
This paper draws on recent debates about scale to approach the geography of labour markets from a dynamic perspective sensitive to the spatiality and scale of labour market
restructuring. Its exploration of labour market reconfigurations after the collapse of a major firm (Ansett Airlines) raises questions about geographyâs faith in the inherently âlocalâ constitution of labour markets. Through an examination of the job reallocation process after redundancy, the paper suggests that multiple labour markets use and articulate scale in different ways. It argues that labour market rescaling processes are enacted at the critical moment of recruitment, where social networks, personal aspirations and employer preferences combine to shape workersâ destinations
The role of BoFLC2 in cauliflower (Brassica oleracea var. botrytis L.) reproductive development
In agricultural species that are sexually propagated or whose marketable organ is a reproductive structure, management of the flowering process is critical. Inflorescence development in cauliflower is particularly complex, presenting unique challenges for those seeking to predict and manage flowering time. In this study, an integrated physiological and molecular approach was used to clarify the environmental control of cauliflower reproductive development at the molecular level. A functional allele of BoFLC2 was identified for the first time in an annual brassica, along with an allele disrupted by a frameshift mutation (boflc2). In a segregating F2 population derived from a cross between late-flowering (BoFLC2) and early-flowering (boflc2) lines, this gene behaved in a dosage-dependent manner and accounted for up to 65% of flowering time variation. Transcription of BoFLC genes was reduced by vernalization, with the floral integrator BoFT responding inversely. Overall expression of BoFT was significantly higher in early-flowering boflc2 lines, supporting the idea that BoFLC2 plays a key role in maintaining the vegetative state. A homologue of Arabidopsis VIN3 was isolated for the first time in a brassica crop species and was up-regulated by two days of vernalization, in contrast to findings in Arabidopsis where prolonged exposure to cold was required to elicit up-regulation. The correlations observed between gene expression and flowering time in controlled-environment experiments were validated with gene expression analyses of cauliflowers grown outdoors under 'natural' vernalizing conditions, indicating potential for transcript levels of flowering genes to form the basis of predictive assays for curd initiation and flowering time
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