6,128 research outputs found
Scaling laws for the decay of multiqubit entanglement
We investigate the decay of entanglement of generalized N-particle
Greenberger-Horne-Zeilinger (GHZ) states interacting with independent
reservoirs. Scaling laws for the decay of entanglement and for its finite-time
extinction (sudden death) are derived for different types of reservoirs. The
latter is found to increase with the number of particles. However, entanglement
becomes arbitrarily small, and therefore useless as a resource, much before it
completely disappears, around a time which is inversely proportional to the
number of particles. We also show that the decay of multi-particle GHZ states
can generate bound entangled states.Comment: Minor mistakes correcte
Robustness of Entanglement as a Resource
The robustness of multipartite entanglement of systems undergoing decoherence
is of central importance to the area of quantum information. Its
characterization depends however on the measure used to quantify entanglement
and on how one partitions the system. Here we show that the unambiguous
assessment of the robustness of multipartite entanglement is obtained by
considering the loss of functionality in terms of two communication tasks,
namely the splitting of information between many parties and the teleportation
of states.Comment: 11 pages, 5 figure
A influência das atividades mineradoras na alteração do pH e da alcalinidade em águas fluviais: o exemplo do rio Capivari, região do carste paranaense.
As atividades de mineração causam vários tipos de impactos ao meio ambiente. Este trabalho apresenta um estudo de impacto sobre recursos hídricos superficiais desenvolvidos numa bacia hidrográfica na região metropolitana de Curitiba (PR), onde se observaram modificações no pH e na alcalinidade nas águas do rio Capivari ocorridas num intervalo médio de doze anos. Foram avaliados 387 dias de amostragem da série 1986/1987 e 1.095 dias da série 1998/2000. Comparando-se as duas séries, observou-se que, ao longo deste período (1986-2000), a média do pH elevou-se, em média, 0,5 unidade, enquanto a alcalinidade aumentou em 15%. De 1980 a 2001, as áreas de mineração desta mesma bacia tiveram uma expansão de aproximadamente 47.000 m2/ano. Avaliações ao longo do rio revelaram, nos locais à jusante e mais próximos das pedreiras, que o pH apresenta valores mais altos, tornando-se alcalino, e a condutividade elétrica aumenta. Esses dados confirmam a hipótese de que a expansão das áreas de mineração provocaria alterações nos valores de pH e de alcalinidade das águas do rio Capivari
Decoupling the effect of mutant amyloid precursor protein (APP) from the effect of plaque on axonal transport dynamics in the living mouse brain: A correlation MRI-microscopy study
The parent protein for amyloid plaques, amyloid precursor protein (APP), mediates cargo‐motor attachments for intracellular transport. Axonal transport is decreased and the distal location of accumulation is altered in transgenic mice expressing human APP with the Swedish and Indiana mutations (APPSwInd) linked to Familial Alzheimer’s Disease, as detected by time‐lapse magnetic resonance imaging (MRI) of transport in living mouse brains (Bearer et al. 2017). Transport is also altered in brains of Down syndrome mice with 3 copies of APP gene. Questions now become whether expression of mutated APP effects transport dynamics independent of plaque, and do plaques alone contribute to transport defects? To address these we used the Tet‐Off system to decouple expression of APPSwInd from presence of plaques, and then studied transport using our MRI technique in three experimental groups of transgenic mice in which the timing and duration of APPSwInd expression, and thereby plaque formation, was altered with doxycycline: Group A (+ plaques, + APPSwInd); Group B (+ plaques, no APPSwInd), and group C (no plaques, + APPSwInd). Manganese‐enhanced MRI (MEMRI) allows us to perform cell biological experiments in live animals with T1‐weighted MRI in a Bruker 11.7T scanner (Medina et al 2016). Time‐lapse MR images were captured before and after stereotactic injection of Mn2+ (3‐5nL) into CA3 of the hippocampus at successive time‐points. Images of multiple individuals were aligned and processed with our automated computational pipeline (Medina et al. 2017) and statistical parametric mapping (SPM) performed. After MRI brains were harvested for
histopathology or biochemistry. Results show that within group between time‐point have altered
transport locations as well as diminished transport in all groups compared to wildtype (p<0.05 FDR n=
36). Preliminary ANOVA between‐group comparisons both by SPM and by region of interest
measurements of images support the visual impression that APPSwInd expression alone may
compromise transport. Groups A and B displayed plaques, but not C, and Western blots showed
APPSwInd expressed 3.2‐fold over normal at sacrifice in Groups A and C but not B, with Aβ detected only
in Groups A and B, where phospho‐tau was also present in dystrophic neurites surrounding plaques.
Cholinergic neurons that project to hippocampus from the medial septal nucleus were decreased in
Group C (p=0.0006 by ANOVA, n=15). Isolated hippocampal vesicles contained Mn2+, as well as Trk (NGF
receptor), Rab 5 and 7 (associated with transport vesicles), suggesting a distinct vesicle population is
affected by these APP mutations. These surprising results implicate mutated APPSwInd in transport
defects, separable from the effect of plaque
Witnessing microtubule-based transport in the living brain: Impact of the cargomotor receptor, amyloid precursor protein, and Alzheimer’s plaques
Most amyloid precursor protein (APP)-based Alzheimer’s models overexpress mutant human APP
resulting in Abeta plaques. Yet the relative contribution of this elevated APP and the presence of
plaques to neurodegeneration remains a big question. APP’s role as a cargo-motor receptor for axonal
transport suggests that overexpression might lead to increased transport. Indeed we showed that
transport is increased in Down’s syndrome and decreased in APP knockout mice. Hence transport may
be elevated in APP overexpressors and lead to either beneficial or deleterious consequences. Here we
use high field microMRI with Mn2+, an MR contrast agent useful as a track-tracer, to pose this cell
biological quest
ion within the whole living brains of wildtype and Alzheimer’s model mice. Injection of
Mn2+ into the CA3 region of the hippocampus results in measurable transport over time. Application of
3D unbiased whole brain image analysis detects all circuitry emanating from the hippocampus. By
driving APP Swe/Ind transgene expression with a tetracycline-sensitive promoter, APPSwe/Ind
expression can be decoupled from the presence of plaques with doxycycline (doxy). Three groups of
mice were studied: group ‘A’ (no doxy, +plaques, +APP); group ‘B’ (doxy at 8 days before sacrifice,
+plaques, no APP), and group ‘C’ (doxy prior to conception, and stopped 8 days before sacrifice, no
plaques, +APP). Images were captured before and sequentionally after Mn2+ injection into CA
3 (1, 7, 25
hr). Images were aligned and analyzed by statistical parametric mapping to identify differential
accumulation within the hippocampal projections. Histopathology revealed well-developed plaques in A
and B, and Western blots showed human APP expressed five-fold over WT in in A and C. Our preliminary
results show increased transport in A and C, with APP Swe/Ind expression when compared with B,
where expression is suppressed. Cholinergic neurons in the medial septal nucleus were decreased as
determined by anti-ChAT staining in Group C (p=0.0006 by one-way ANOVA, n=15). In conclusion, the
effects of elevated APP expression are separable from consequences of plaque, and each may
Developing a Model for Slow Hypoxic Injury and Vascular Degeneration in Amyloid Burdened Brains
The breakdown of neurovascular systems may play a crucial role in the pathogenesis of Alzheimer’s
disease. However whether this breakdown initiates a degenerative mechanism or is the consequence of
some other deleterious process remains unknown. We examined hippocampal pathology in double
transgenic mice overexpressing a human mutant gene encoding the amyloid precursor protein
(APPSwe/Ind) using a combination of histochemistry and stereologic techniques. Expression of
APPSwe/Ind in these mice is driven by a tetracycline-sensitive promoter. Tetracycline transcriptional
activator (tTA), the second transgene, is driven in turn by a CAM KIIa promoter that is only active in
neurons. Thus this double transgenic construct allows us to control expression of APPSwe/Ind with
doxycycline. Utilizing this characteristic, we created three distinct experimental groups: A, display abeta
plaque pathology and express APPSwe/Ind at time of sacrifice; B, display abeta plaque pathology but do
not express APPSwe/Ind at time of sacrifice; and C, do not display abeta plaque pathology but do
express APPSwe/Ind at time of sacrifice. Stereologic investigation revealed decreased hippocampal
volume in groups A(n=5) and B(n=5) when compared to group C(n=5) and age-matched wildtype (n=9)
LPIN1 deficiency: A novel mutation associated with different phenotypes in the same family
Free PMC Article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5050266/Rhabdomyolysis (RM) is characterized by acute and often severe skeletal muscle damage resulting in myoglobinuria and, in severe cases, acute renal failure. In adults is typically due to trauma, intoxication or infection, whereas in children is frequently associated with inherited muscle disorders. LPIN1 mutations were identified as a cause of severe recurrent RM, which usually begin in childhood, and infections are the most frequent trigger.info:eu-repo/semantics/publishedVersio
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