122 research outputs found
Meditation-induced bliss viewed as release from conditioned neural (thought) patterns that block reward signals in the brain pleasure center
The nucleus accumbens orchestrates processes related to reward and pleasure,
including the addictive consequences of repeated reward (e.g., drug addiction and
compulsive gambling) and the accompanying feelings of craving and anhedonia.
The neurotransmitters dopamine and endogenous opiates play interactive roles in
these processes. They are released by natural rewards (i.e., food, water, sex, money,
play, etc.) and are released or mimicked by drugs of abuse. Repeated drug use
induces conditioned down-regulation of these neurotransmitters, thus causing
painful suppression of everyday pleasure. As with many spiritual traditions,
Buddhism provides strong advice against the pursuit of worldly pleasures to
attain the ââgood life.ââ In contrast, many forms of meditation give rise to an
immense and abiding joy. Most of these practices involve ââstilling the mind,ââ
whereby all content-laden thought (e.g., fantasies, daydreams, plans) ceases, and
the mind enters a state of openness, formlessness, clarity, and bliss. This can be
explained by the Buddhist suggestion that almost all of our everyday thoughts are
a form of addiction. It follows that if we turn off this internal ââgossip of ego,ââ we
will find relief from the biochemical dopamine/opiate down-regulation, which is,
perhaps, the perpetual concomitant of our daily rumination
Random Mass Dirac Fermions in Doped Spin-Peierls and Spin-Ladder systems: One-Particle Properties and Boundary Effects
Quasi-one-dimensional spin-Peierls and spin-ladder systems are characterized
by a gap in the spin-excitation spectrum, which can be modeled at low energies
by that of Dirac fermions with a mass. In the presence of disorder these
systems can still be described by a Dirac fermion model, but with a random
mass. Some peculiar properties, like the Dyson singularity in the density of
states, are well known and attributed to creation of low-energy states due to
the disorder. We take one step further and study single-particle correlations
by means of Berezinskii's diagram technique. We find that, at low energy
, the single-particle Green function decays in real space like
. It follows that at these energies the
correlations in the disordered system are strong -- even stronger than in the
pure system without the gap. Additionally, we study the effects of boundaries
on the local density of states. We find that the latter is logarithmically (in
the energy) enhanced close to the boundary. This enhancement decays into the
bulk as and the density of states saturates to its bulk value on
the scale . This scale is different from
the Thouless localization length . We
also discuss some implications of these results for the spin systems and their
relation to the investigations based on real-space renormalization group
approach.Comment: 26 pages, LaTex, 9 PS figures include
Middle to late Pleistocene palaeoecological reconstructions and palaeotemperature estimates for cold/cool stage deposits at Whittlesey, eastern England
Fossiliferous beds in a complex sequence of late Middle to Late Pleistocene deposits at Whittlesey, eastern England, provided a rare opportunity for a multidisciplinary study of the palaeoecology of cool/cold stage deposits from different glacial stages. The fossiliferous sediments investigated form part of the River Nene 1st Terrace. Three of the four fossil assemblages investigated pre-date the last interglacial stage (Ipswichian/Eemian/marine oxygen isotope stage (MIS) 5e), whereas the other dates to part of the MIS 3 interstadial complex (Middle Devensian/Weichselian). Pollen, plant macrofossil, molluscan, coleopteran, ostracod, foraminifera and vertebrate data are available to a greater or lesser extent for each cool/cold stage assemblage, and they broadly present the same ecological picture for each one: a continuum from low-energy permanent to non-permanent aquatic habitats through marshland with associated waterside taxa, together with flood influxes of fluvial, riparian and ruderal taxa. Although each fossil assemblage records cool/cold climatic conditions, to a greater or lesser extent, these conditions are more apparent in the insect and ostracod faunas. In comparison with results published for the Last Glacial Maximum (LGM) stadial in The Netherlands, palaeotemperature estimates based on ranges of mutual agreement between independent coleopteran and ostracod methods for the three pre-Ipswichian/Eemian assemblages indicate minimum mean July air temperatures that are from +1° to +3 °C warmer, but January values that embrace the â8 °C estimate for the LGM. There is, however, a disparity between the coleopteran and ostracod palaeotemperature estimates for the Middle Devensian/Weichselian fossil assemblage, which are based on two different sample stratigraphic levels; the lower, coleopteran assemblage is indicative of very cool, continental climates, whereas the stratigraphically slightly higher ostracod assemblage suggests a climatic amelioration. Lack of numerical age-estimates prevents a robust stratigraphical interpretation, but the youngest pre-Ipswichian/Eemian fossil assemblage could date to the MIS 7â6 transition, at a time when cooling possibly preceded glacially driven sea-level fall. It is apparent from the rich coleopteran data that some continental cold-indicator taxa also appeared in pre-Ipswichian/Eemian cold stages and therefore assignment of continental cold-indicator taxa to particular Devensian/Weichselian intervals should be undertaken with care
LivestockPlus: The sustainable intensification of forage-based agricultural systems to improve livelihoods and ecosystem services in the tropics
As global demand for livestock products (such as meat, milk, and eggs) is expected to double by 2050, necessary
increases to future production must be reconciled with negative environmental impacts that livestock cause. This
paper describes the LivestockPlus concept and demonstrates how the sowing of improved forages can lead to the
sustainable intensification of mixed cropâforageâlivestockâtree systems in the tropics by producing multiple social,
economic, and environmental benefits. Sustainable intensification not only improves the productivity of tropical
forage-based systems but also reduces the ecological footprint of livestock production and generates a diversity of
ecosystem services (ES), such as improved soil quality and reduced erosion, sedimentation, and greenhouse gas
(GHG) emissions. Integrating improved grass and legume forages into mixed production systems (cropâlivestock,
treeâlivestock, cropâtreeâlivestock) can restore degraded lands and enhance system resilience to drought and
waterlogging associated with climate change. When properly managed tropical forages accumulate large amounts
of carbon in soil, fix atmospheric nitrogen (legumes), inhibit nitrification in soil and reduce nitrous oxide emissions
(grasses), and reduce GHG emissions per unit livestock product.
The LivestockPlus concept is defined as the sustainable intensification of forage-based systems, which is based
on three interrelated intensification processes: genetic intensification â the development and use of superior
grass and legume cultivars for increased livestock productivity; ecological intensification â the development and
application of improved farm and natural resource management practices; and socio-economic intensification
â the improvement of local and national institutions and policies, which enable refinements of technologies
and support their enduring use. Increases in livestock productivity will require coordinated efforts to develop
supportive government, non-government organization, and private sector policies that foster investments and
fair market compensation for both the products and ES provided. Effective research-for-development efforts that
promote agricultural and environmental benefits of forage-based systems can contribute towards implemention of
LivestockPlus across a variety of geographic, political, and socio-economic contexts
Rare genetic variants explain missing heritability in smoking
Common genetic variants explain less variation in complex phenotypes than inferred from family-based studies, and there is a debate on the source of this âmissing heritabilityâ. We investigated the contribution of rare genetic variants to tobacco use with whole-genome sequences from up to 26,257 unrelated individuals of European ancestries and 11,743 individuals of African ancestries. Across four smoking traits, single-nucleotide-polymorphism-based heritability (hSNP2) was estimated from 0.13 to 0.28 (s.e., 0.10â0.13) in European ancestries, with 35â74% of it attributable to rare variants with minor allele frequencies between 0.01% and 1%. These heritability estimates are 1.5â4 times higher than past estimates based on common variants alone and accounted for 60% to 100% of our pedigree-based estimates of narrow-sense heritability (hped2, 0.18â0.34). In the African ancestry samples, hSNP2 was estimated from 0.03 to 0.33 (s.e., 0.09â0.14) across the four smoking traits. These results suggest that rare variants are important contributors to the heritability of smoking
Soluble forms of tau are toxic in Alzheimer's disease
Accumulation of neurofibrillary tangles (NFT), intracellular inclusions of fibrillar forms of tau, is a hallmark of Alzheimer Disease. NFT have been considered causative of neuronal death, however, recent evidence challenges this idea. Other species of tau, such as soluble misfolded, hyperphosphorylated, and mislocalized forms, are now being implicated as toxic. Here we review the data supporting soluble tau as toxic to neurons and synapses in the brain and the implications of these data for development of therapeutic strategies for Alzheimerâs disease and other tauopathies
Anticholinesterase and Antioxidant Activities of Spilanthes filicaulis Whole Plant Extracts for the Management of Alzheimerâs Disease
Background: Spilanthes filicaulis is a tropical herb implicated as a memory enhancer in ethnomedicine. Objective: The study investigated acetyl/butyryl cholinesterase inhibitory and antioxidant activities of different extracts of S. filicaulis whole plant and correlated them to its phytochemical constituents. Methods: The powdered whole plant was successively extracted with n-hexane, ethyl acetate and methanol. Acetyl cholinesterase (AChE) and Butyryl cholinesterase (BuChE) inhibitory activity were evaluated by Ellman colorimetry assay. Antioxidant activity was tested using 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ferric reducing power and nitric oxide scavenging assays. Total phenolic, flavonoid and tannin were estimated using standard methods. Correlation was determined using Quest Graphâą Regression Calculator. Results: Various extracts exhibited concentration-dependent AChE and BuChE inhibitory activity with ethyl acetate extract being the highest with IC50 of 0.77 ÎŒg/mL and 0.92 ÎŒg/mL for AChE and BuChE respectively. The ethyl acetate extract also showed the highest reducing power when compared with the other extracts. The methanol extract had slightly higher phenolic and flavonoid content and showed the highest DPPH radical scavenging effect. DPPH scavenging, AChE and BuChE inhibition had high correlation with the total flavonoid content with R2 values of 1.00, 0.800 and 0.992 respectively while nitric oxide scavenging had high correlation with phenolics and tannins with R2 = 0.942 and 0.806 respectively. Conclusion: These results show that the extracts of the whole plant of S. filicaulis possess significant AChE/BuChE inhibitory and antioxidant properties, mostly due to its flavonoid content, suggesting the possible use of the plant in neurodegenerative diseases such as AD
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