30 research outputs found
Carbonate alteration of ophiolitic rocks in the ArabianâNubian Shield of Egypt: sources and compositions of the carbonating fluid and implications for the formation of Au deposits
Ultramafic portions of ophiolitic fragments in the ArabianâNubian Shield (ANS) show pervasive carbonate alteration forming various degrees of carbonated serpentinites and listvenitic rocks. Notwithstanding the extent of the alteration, little is known about the processes that caused it, the source of the CO2 or the conditions of alteration. This study investigates the mineralogy, stable (O, C) and radiogenic (Sr) isotope composition, and geochemistry of suites of variably carbonate altered ultramafics from the Meatiq area of the Central Eastern Desert (CED) of Egypt. The samples investigated include least-altered lizardite (Lz) serpentinites, antigorite (Atg) serpentinites and listvenitic rocks with associated carbonate and quartz veins. The C, O and Sr isotopes of the vein samples cluster between â8.1â° and â6.8â° for ÎŽ13C, +6.4â° and +10.5â° for ÎŽ18O, and 87Sr/86Sr of 0.7028â0.70344, and plot within the depleted mantle compositional field. The serpentinites isotopic compositions plot on a mixing trend between the depleted-mantle and sedimentary carbonate fields. The carbonate veins contain abundant carbonic (CO2±CH4±N2) and aqueous-carbonic (H2O-NaCl-CO2±CH4±N2) low salinity fluid, with trapping conditions of 270â300°C and 0.7â1.1 kbar. The serpentinites are enriched in Au, As, S and other fluid-mobile elements relative to primitive and depleted mantle. The extensively carbonated Atg-serpentinites contain significantly lower concentrations of these elements than the Lz-serpentinites suggesting that they were depleted during carbonate alteration. Fluid inclusion and stable isotope compositions of Au deposits in the CED are similar to those from the carbonate veins investigated in the study and we suggest that carbonation of ANS ophiolitic rocks due to influx of mantle-derived CO2-bearing fluids caused break down of Au-bearing minerals such as pentlandite, releasing Au and S to the hydrothermal fluids that later formed the Au-deposits. This is the first time that gold has been observed to be remobilized from rocks during the lizarditeâantigorite transition
Getting shot of elves: healing, witchcraft and fairies in the Scottish witchcraft trials
This paper re-examines the evidence of the Scottish witchcraft trials for beliefs associated by scholars with "elf-shot." Some supposed evidence for elf-shot is dismissed, but other material illuminates the interplay between illness, healing and fairy-lore in early modern Scotland, and the relationship of these beliefs to witchcraft itself
Reciprocal effects of alpha-synuclein aggregation and lysosomal homeostasis in synucleinopathy models
Abstract
Background
Lysosomal dysfunction has been implicated in a number of neurodegenerative diseases such as Parkinsonâs disease (PD). Various molecular, clinical and genetic studies have highlighted a central role of lysosomal pathways and proteins in the pathogenesis of PD. Within PD pathology the synaptic protein alpha-synuclein (αSyn) converts from a soluble monomer to oligomeric structures and insoluble amyloid fibrils. The aim of this study was to unravel the effect of αSyn aggregates on lysosomal turnover, particularly focusing on lysosomal homeostasis and cathepsins. Since these enzymes have been shown to be directly involved in the lysosomal degradation of αSyn, impairment of their enzymatic capacity has extensive consequences.
Methods
We used patient-derived induced pluripotent stem cells and a transgenic mouse model of PD to examine the effect of intracellular αSyn conformers on cell homeostasis and lysosomal function in dopaminergic (DA) neurons by biochemical analyses.
Results
We found impaired lysosomal trafficking of cathepsins in patient-derived DA neurons and mouse models with αSyn aggregation, resulting in reduced proteolytic activity of cathepsins in the lysosome. Using a farnesyltransferase inhibitor, which boosts hydrolase transport via activation of the SNARE protein ykt6, we enhanced the maturation and proteolytic activity of cathepsins and thereby decreased αSyn protein levels.
Conclusions
Our findings demonstrate a strong interplay between αSyn aggregation pathways and function of lysosomal cathepsins. It appears that αSyn directly interferes with the enzymatic function of cathepsins, which might lead to a vicious cycle of impaired αSyn degradation.
Graphical abstract
Lysosomal trafficking of cathepsin D (CTSD), CTSL and CTSB is disrupted when alpha-synuclein (αSyn) is aggregated. This results in a decreased proteolytic activity of cathepsins, which directly mediate αSyn clearance. Boosting the transport of the cathepsins to the lysosome increases their activity and thus contributes to efficient αSyn degradation.
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Franchises lost and gained: post-coloniality and the development of womenâs rights in Canada
The Canadian constitution is to some extent characterised by its focus on equality, and in particular gender equality. This development of womenâs rights in Canada and the greater engagement of women as political actors is often presented as a steady linear process, moving forwards from post-enlightenment modernity. This article seeks to disturb this âdiscourse of the continuous,â by using an analysis of the pre-confederation history of suffrage in Canada to both refute a simplistic linear view of womenâs rights development and to argue for recognition of the Indigenous contribution to the history of womenâs rights in Canada.
The gain of franchise and suffrage movements in Canada in the late nineteenth and early twentieth century are, rightly, the focus of considerable study (Pauker 2015), This article takes an alternative perspective. Instead, it examines the exercise of earlier franchises in pre-confederation Canada. In particular it analyses why franchise was exercised more widely in Lower Canada and relates this to the context of the removal of franchises from women prior to confederation
Addressing Criticisms of Large-Scale Marine Protected Areas
Designated large-scale marine protected areas (LSMPAs, 100,000 or more square kilometers) constitute over two-thirds of the approximately 6.6% of the ocean and approximately 14.5% of the exclusive economic zones within marine protected areas. Although LSMPAs have received support among scientists and conservation bodies for wilderness protection, regional ecological connectivity, and improving resilience to climate change, there are also concerns. We identified 10 common criticisms of LSMPAs along three themes: (1) placement, governance, and management; (2) political expediency; and (3) socialâecological value and cost. Through critical evaluation of scientific evidence, we discuss the value, achievements, challenges, and potential of LSMPAs in these arenas. We conclude that although some criticisms are valid and need addressing, none pertain exclusively to LSMPAs, and many involve challenges ubiquitous in management. We argue that LSMPAs are an important component of a diversified management portfolio that tempers potential losses, hedges against uncertainty, and enhances the probability of achieving sustainably managed oceans
The search for tensor interactions in the beta-decay of polarized âžâ°Rb
The spin polarized nuclear recoil asymmetry from ÎČ emission is nearly zero in the standard
model. This observable is sensitive to tensor interactions which exist in certain standard
model extensions.
The nuclear recoil energy is very small (a few eV) and therefore requires a sensitively
controlled environment for measurement, the TRINAT atom trap provides such an environment.
Rudidium-80 is an unstable isotope which ÎČ-decays (positron emission or electron capture)
with a half life of 30s. It is produced in large quantities at the ISAC facility located
in TRIUMF. This isotope offers favorable nuclear and atomic properties for measurement
in the TRINAT apparatus. Rubidium-80 is trapped in a vacuum by lasers combined with a
magnetic field, and polarized with another laser. When the trapped Rubidium decays the
sudden change of nuclear charge typically ejects a few low energy atomic electrons leaving a
positive ion. An electric field accelerates the ions towards a position sensitive microchannel
plate and the electrons to another microchannel plate.
The direction of polarization is parallel to the plates surface, so an asymmetry manifests
itself as a difference in the distribution of ion impacts when the polarization is inverted.
The ion time of flight is used to discriminate between positron emission and electron
capture events. This discrimination is required since electron capture has a large asymmetry
in the standard model which would overwhelm the desired observable.
There is a small polarization asymmetry expected to occur even within the standard
model due to "recoil order" corrections to the V-A theory. Since these "recoil order" corrections
have yet to be theoretically calculated, they are left as fit parameters. Unfortunately
the data is statistically insufficient to fit both the "recoil order" corrections and the tensor
couplings simultaneously. However, if the "recoil order" corrections are fixed to a crude theoretical
estimate a fit for tensor couplings sets limits consistent with zero and complementary
to other experimental results, namely nuclear recoils in He-6 and positron-polarization from
C-10. Theoretical limits based on neutrino mass and naturalness arguments remain more
restrictive at this time.Science, Faculty ofPhysics and Astronomy, Department ofGraduat