Rangelands of the Qinghai-Tibetan plateau (QTP), although sparsely populated and contributing little to China's overall economy, play an important environmental role throughout Asia. They contain ...high biodiversity values and can also potentially provide China with a source of cultural and geographic variety in the future. Chinese government reports paint a gloomy picture, considering vast portions of the QTP degraded and blaming irrational overstocking of livestock as the principal culprit. Global climate change, population increases, and “rodent” damage are also invoked as causes of rangeland degradation. In contrast, some Western observers claim that traditional pastoral practices were sustainable, and identify either previous or more recent state policies as the cause of degradation. Chinese governments at national and provincial levels have initiated a number of sometimes-conflicting and confusing policies aimed, at least nominally, at restoring rangeland productivity. On the basis of a comprehensive literature review, I argue that the extent and magnitude of rangeland degradation on the QTP remains largely unknown because monitoring programs have been subjective and poorly documented. Further, I argue that causes of degradation remain uncertain, often because hypotheses have been articulated too vaguely to test. No phenomena that have been hypothesized as contributing to rangeland degradation on the QTP currently enjoy unequivocal support. Where over-stocking is clearly causing damage, we lack sufficient understanding of current socio-ecological systems to identify ultimate and proximate drivers of pastoralist behavior, and thus policy initiatives aimed at sustainability may well fail.
•Caffeine in beverages and foods blocks central and peripheral adenosine receptors.•Low (40mg, 0.5mgkg−1) to moderate (300mg, 4mgkg−1) doses improve cognition.•Doses >200mg (∼3mgkg−1) are ergogenic ...across a spectrum of exercise modalities.•Caffeine is effective to offset physical and cognitive degradation with sleep loss.
Caffeine is consumed by over 80% of U.S. adults. This review examines the effects caffeine has on cognitive and physical function, since most real-world activities require complex decision making, motor processing and movement. Caffeine exerts its effects by blocking adenosine receptors. Following low (∼40mg or ∼0.5mgkg−1) to moderate (∼300mg or 4mgkg−1) caffeine doses, alertness, vigilance, attention, reaction time and attention improve, but less consistent effects are observed on memory and higher-order executive function, such as judgment and decision making. Effects on physical performance on a vast array of physical performance metrics such as time-to-exhaustion, time-trial, muscle strength and endurance, and high-intensity sprints typical of team sports are evident following doses that exceed about 200mg (∼3mgkg−1). Many occupations, including military, first responders, transport workers and factory shift workers, require optimal physical and cognitive function to ensure success, workplace safety and productivity. In these circumstances, that may include restricted sleep, repeated administration of caffeine is an effective strategy to maintain physical and cognitive capabilities.
This paper formulates the action of psychedelics by integrating the free-energy principle and entropic brain hypothesis. We call this formulation relaxed beliefs under psychedelics (REBUS) and the ...anarchic brain, founded on the principle that-via their entropic effect on spontaneous cortical activity-psychedelics work to relax the precision of high-level priors or beliefs, thereby liberating bottom-up information flow, particularly via intrinsic sources such as the limbic system. We assemble evidence for this model and show how it can explain a broad range of phenomena associated with the psychedelic experience. With regard to their potential therapeutic use, we propose that psychedelics work to relax the precision weighting of pathologically overweighted priors underpinning various expressions of mental illness. We propose that this process entails an increased sensitization of high-level priors to bottom-up signaling (stemming from intrinsic sources), and that this heightened sensitivity enables the potential revision and deweighting of overweighted priors. We end by discussing further implications of the model, such as that psychedelics can bring about the revision of other heavily weighted high-level priors, not directly related to mental health, such as those underlying partisan and/or overly-confident political, religious, and/or philosophical perspectives. SIGNIFICANCE STATEMENT: Psychedelics are capturing interest, with efforts underway to bring psilocybin therapy to marketing authorisation and legal access within a decade, spearheaded by the findings of a series of phase 2 trials. In this climate, a compelling unified model of
psychedelics alter brain function to alter consciousness would have appeal. Towards this end, we have sought to integrate a leading model of global brain function,
, with an often-cited model of the acute action of psychedelics,
. The resulting synthesis states that psychedelics work to relax high-level priors, sensitising them to liberated bottom-up information flow, which, with the right intention, care provision and context, can help guide and cultivate the revision of entrenched pathological priors.
Previous attempts to identify a unified theory of brain serotonin function have largely failed to achieve consensus. In this present synthesis, we integrate previous perspectives with new and older ...data to create a novel bipartite model centred on the view that serotonin neurotransmission enhances two distinct adaptive responses to adversity, mediated in large part by its two most prevalent and researched brain receptors: the 5-HT1A and 5-HT2A receptors. We propose that passive coping (i.e. tolerating a source of stress) is mediated by postsynaptic 5-HT1AR signalling and characterised by stress moderation. Conversely, we argue that active coping (i.e. actively addressing a source of stress) is mediated by 5-HT2AR signalling and characterised by enhanced plasticity (defined as capacity for change). We propose that 5-HT1AR-mediated stress moderation may be the brain’s default response to adversity but that an improved ability to change one’s situation and/or relationship to it via 5-HT2AR-mediated plasticity may also be important – and increasingly so as the level of adversity reaches a critical point. We propose that the 5-HT1AR pathway is enhanced by conventional 5-HT reuptake blocking antidepressants such as the selective serotonin reuptake inhibitors (SSRIs), whereas the 5-HT2AR pathway is enhanced by 5-HT2AR-agonist psychedelics. This bipartite model purports to explain how different drugs (SSRIs and psychedelics) that modulate the serotonergic system in different ways, can achieve complementary adaptive and potentially therapeutic outcomes.
Iodine is a mineral nutrient essential for the regulation of a variety of key physiological functions including metabolism and brain development and function in children and adults. As such, iodine ...intake and status within populations is an area of concern and research focus. This paper will review recently published studies that focus on the re-emerging issue of iodine deficiency as a global concern and declining intake among populations in developed countries. Historically, the implementation of salt-iodization programs worldwide has reduced the incidence of iodine deficiency, but 30% of the world’s population is still at risk. Iodine nutrition is a growing issue within industrialized countries including the U.S. as a result of declining iodine intake, in part due to changing dietary patterns and food manufacturing practices. Few countries mandate universal salt iodization policies, and differing agriculture and industry practices and regulations among countries have resulted in inconsistencies in supplementation practices. In the U.S., in spite of salt-iodization policies, mild-to-moderate iodine deficiency is common and appears to be increasing. European countries with the highest incidence of deficiency lack iodization programs. Monitoring the iodine status of at-risk populations and, when appropriate, public health initiatives, appear to be warranted.
Alcohol abuse causes widespread changes in gene expression in human brain, some of which contribute to alcohol dependence. Previous microarray studies identified individual genes as candidates for ...alcohol phenotypes, but efforts to generate an integrated view of molecular and cellular changes underlying alcohol addiction are lacking. Here, we applied a novel systems approach to transcriptome profiling in postmortem human brains and generated a systemic view of brain alterations associated with alcohol abuse. We identified critical cellular components and previously unrecognized epigenetic determinants of gene coexpression relationships and discovered novel markers of chromatin modifications in alcoholic brain. Higher expression levels of endogenous retroviruses and genes with high GC content in alcoholics were associated with DNA hypomethylation and increased histone H3K4 trimethylation, suggesting a critical role of epigenetic mechanisms in alcohol addiction. Analysis of cell-type-specific transcriptomes revealed remarkable consistency between molecular profiles and cellular abnormalities in alcoholic brain. Based on evidence from this study and others, we generated a systems hypothesis for the central role of chromatin modifications in alcohol dependence that integrates epigenetic regulation of gene expression with pathophysiological and neuroadaptive changes in alcoholic brain. Our results offer implications for epigenetic therapeutics in alcohol and drug addiction.
Psychedelics and connectedness Carhart-Harris, R. L.; Erritzoe, D.; Haijen, E. ...
Psychopharmacology,
02/2018, Letnik:
235, Številka:
2
Journal Article
Recenzirano
Psychedelic drugs are creating ripples in psychiatry as evidence accumulates of their therapeutic potential. An important question remains unresolved however:
how
are psychedelics effective? We ...propose that a sense of
connectedness
is key, provide some preliminary evidence to support this, and suggest a roadmap for testing it further.
In this work, the Angell analysis of Walden plots of the conductivity of ionic liquids and other electrolytes against viscosity is used to examine simple molten salts at high temperatures, a test ...that does not appear to have been made previously. It is found that many simple salts such as alkali metal fluorides and chlorides are predicted to be “superionic” as their Walden plots fall above the arbitrary reference line introduced by Angell, which passes through the datum point for 1 M aqueous KCl at 25 °C. This contradicts long-standing molecular dynamics evidence in the literature showing that these salts conduct simply by ion migration in an electric field. Zinc chloride is also predicted to be “ideal”, whereas one would expect it to be “subionic” in Angell’s terminology given that it is an associated salt. Results for certain protic ionic liquids are also contradictory. Therefore, Angell–Walden analyses of this type do not convey any useful information other than a qualitative ranking of the conductivity of similar ionic liquids at a given viscosity and their use for estimating “ionicity” is best discontinued. It cannot and should not be used for classifying the interactions in ionic liquids. Instead, it is argued that an examination of Laity resistance coefficients is more useful in any discussion of true association in molten salts and ionic liquids where known examples show negative like-ion resistance coefficients with NE deviation parameters close to unity. Such an approach could be more fruitful in understanding the transport properties of molten salts and ionic liquids rather than simple comparisons of viscosity and conductivity.
Aerosol Jet Printing (AJP) is an emerging contactless direct write approach aimed at the production of fine features on a wide range of substrates. Originally developed for the manufacture of ...electronic circuitry, the technology has been explored for a range of applications, including, active and passive electronic components, actuators, sensors, as well as a variety of selective chemical and biological responses. Freeform deposition, coupled with a relatively large stand-off distance, is enabling researchers to produce devices with increased geometric complexity compared to conventional manufacturing or more commonly used direct write approaches. Wide material compatibility, high resolution and independence of orientation have provided novelty in a number of applications when AJP is conducted as a digitally driven approach for integrated manufacture. This overview of the technology will summarise the underlying principles of AJP, review applications of the technology and discuss the hurdles to more widespread industry adoption. Finally, this paper will hypothesise where gains may be realised through this assistive manufacturing process.
A molecular dynamics study is done on cuboid and spherical Fe
3
O
4
magnetic nanoparticles (NPs) to investigate qualitatively the influence of the molecules NH
4
OH and NaOH on their binding energy. ...This is done to determine the stability and therefore likely shape (morphology) and size of the synthesized NPs when these molecules are used as stabilizing agents. We show through molecular dynamics (MD) that small, spherical NPs synthesized with NH
4
OH, and large, cuboid NPs synthesized with NaOH, are the most stable NP systems and therefore the most likely outcome of a synthesis experiment. Furthermore, we synthesize these systems under similar conditions as predicted and find that when NaOH is used large (29 ± 2 nm), cuboid NPs are formed and when NH
4
OH is used, small (11 nm ± 2 nm), spherical NPs are formed. The role of pH is further investigated using the desorbed (and unadsorbed hydroxyl groups) as indicators of pH. The magnetic NPs are then synthesized via the co-precipitation method and the resulting NPs characterized for crystallinity, morphology, size and magnetic properties.
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