154 research outputs found
Molecular and Epigenetic Mechanisms Underlying Cognitive and Adaptive Responses to Stress
Consolidation of contextual memories after a stressful encounter is essential for the survival of an organism and in allowing a more appropriate response to be elicited should the perceived threat reoccur. Recent evidence has explored the complex role that epigenetic mechanisms play in the formation of such memories, and the underlying signaling pathways are becoming more apparent. The glucocorticoid receptor (GR) has been shown to play a key role in these events having both genomic and non-genomic actions in the brain. GR has been shown to interact with the extracellular signal-regulated kinase mitogen-activated protein kinase (ERK MAPK) signaling pathway which, in concert, drives epigenetic modifications and chromatin remodeling, resulting in gene induction and memory consolidation. Evidence indicates that stressful events can have an effect on the offspring in utero, and that epigenetic marks altered early in life may persist into adulthood. A new and controversial area of research, however, suggests that epigenetic modifications could be inherited through the germline, a concept known as transgenerational epigenetics. This review explores the role that epigenetic processes play in the central nervous system, specifically in the consolidation of stress-induced memories, the concept of transgenerational epigenetic inheritance, and the potential role of epigenetics in revolutionizing the treatment of stress-related disorders through the emerging field of pharmacoepigenetics and personalized medical treatment
How large are the level sets of the Takagi function?
Let T be Takagi's continuous but nowhere-differentiable function. This paper
considers the size of the level sets of T both from a probabilistic point of
view and from the perspective of Baire category. We first give more elementary
proofs of three recently published results. The first, due to Z. Buczolich,
states that almost all level sets (with respect to Lebesgue measure on the
range of T) are finite. The second, due to J. Lagarias and Z. Maddock, states
that the average number of points in a level set is infinite. The third result,
also due to Lagarias and Maddock, states that the average number of local level
sets contained in a level set is 3/2. In the second part of the paper it is
shown that, in contrast to the above results, the set of ordinates y with
uncountably infinite level sets is residual, and a fairly explicit description
of this set is given. The paper also gives a negative answer to a question of
Lagarias and Maddock by showing that most level sets (in the sense of Baire
category) contain infinitely many local level sets, and that a continuum of
level sets even contain uncountably many local level sets. Finally, several of
the main results are extended to a version of T with arbitrary signs in the
summands.Comment: Added a new Section 5 with generalization of the main results; some
new and corrected proofs of the old material; 29 pages, 3 figure
Governors and directors: Competing models of corporate governance
Why do we use the term ‘corporate governance’ rather than ‘corporate direction’? Early British joint stock companies were normally managed by a single ‘governor’. The ‘court of governors’ or ‘board of directors’ emerged slowly as the ruling body for companies. By the nineteenth century, however, companies were typically run by directors while not-for-profit entities such as hospitals, schools and charitable bodies had governors. The nineteenth century saw steady refinement of the roles of company directors, often in response to corporate scandals, with a gradual change from the notion of the director as a ‘representative shareholder’ to the directors being seen collectively as ‘representatives of the shareholders’. Governors in not-for-profit entities, however, were regarded as having broader responsibilities. The term ‘governance’ itself suggests that corporate boards should be studied as ‘political’ entities rather than merely through economic lenses such as agency theory
United in Separation? Lozi Secessionism in Zambia and Namibia
Secessionism perseveres as a complex political phenomenon in Africa, yet often a more in-depth analysis is overshadowed by the aspirational simplicity of pursuing a new state. Using historical and contemporary approaches, this edited volume offers the most exhaustive collection of empirical studies of African secessionism to date. The respected expert contributors put salient and lesser known cases into comparative perspective, covering Biafra, Katanga, Eritrea and South Sudan alongside Barotseland, Cabinda, and the Comoros, among others. Suggesting that African secessionism can be understood through the categories of aspiration, grievance, performance, and disenchantment, the book's analytical framework promises to be a building block for future studies of the topic
Biomass burning fuel consumption rates: a field measurement database
Landscape fires show large variability in the amount of biomass or fuel consumed per unit area burned. Fuel consumption (FC) depends on the biomass available to burn and the fraction of the biomass that is actually combusted, and can be combined with estimates of area burned to assess emissions. While burned area can be detected from space and estimates are becoming more reliable due to improved algorithms and sensors, FC is usually modeled or taken selectively from the literature. We compiled the peerreviewed literature on FC for various biomes and fuel categories to understand FC and its variability better, and to provide a database that can be used to constrain biogeochemical models with fire modules. We compiled in total 77 studies covering 11 biomes including savanna (15 studies, average FC of 4.6 t DM (dry matter) ha 1 with a standard deviation of 2.2),tropical forest (n = 19, FC = 126 +/- 77),temperate forest (n = 12, FC = 58 +/- 72),boreal forest (n = 16, FC = 35 +/- 24),pasture (n = 4, FC = 28 +/- 9.3),shifting cultivation (n = 2, FC = 23, with a range of 4.0-43),crop residue (n = 4, FC = 6.5 +/- 9.0),chaparral (n = 3, FC = 27 +/- 19),tropical peatland (n = 4, FC = 314 +/- 196),boreal peatland (n = 2, FC = 42 [42-43]),and tundra (n = 1, FC = 40). Within biomes the regional variability in the number of measurements was sometimes large, with e. g. only three measurement locations in boreal Russia and 35 sites in North America. Substantial regional differences in FC were found within the defined biomes: for example, FC of temperate pine forests in the USA was 37% lower than Australian forests dominated by eucalypt trees. Besides showing the differences between biomes, FC estimates were also grouped into different fuel classes. Our results highlight the large variability in FC, not only between biomes but also within biomes and fuel classes. This implies that substantial uncertainties are associated with using biome-averaged values to represent FC for whole biomes. Comparing the compiled FC values with co-located Global Fire Emissions Database version 3 (GFED3) FC indicates that modeling studies that aim to represent variability in FC also within biomes, still require improvements as they have difficulty in representing the dynamics governing FC
The histone methyltransferase SDG8 mediates the epigenetic modification of light and carbon responsive genes in plants
“A Hideous Torture on Himself”: Madness and Self-Mutilation in Victorian Literature
This paper suggests that late nineteenth-century definitions of self-mutilation, a new category of psychiatric symptomatology, were heavily influenced by the use of selfinjury as a rhetorical device in the novel, for the literary text held a high status in Victorian psychology. In exploring Dimmesdale’s “self-mutilation” in The Scarlet Letter in conjunction with psychiatric case histories, the paper indicates a number of common techniques and themes in literary and psychiatric texts. As well as illuminating key elements of nineteenth-century conceptions of the self, and the relation of mind and body through ideas of madness, this exploration also serves to highlight the social commentary implicit in many Victorian medical texts. Late nineteenth-century England, like mid-century New England, required the individual to help himself and, simultaneously, others; personal charity and individual philanthropy were encouraged, while state intervention was often presented as dubious. In both novel and psychiatric text, self-mutilation is thus presented as the ultimate act of selfish preoccupation, particularly in cases on the “borderlands” of insanity
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