A
bstract
The Weak Gravity Conjecture (WGC) demands the existence of superextremal particles in any consistent quantum theory of gravity. The standard lore is that these particles are introduced to ...ensure that extremal black holes are either unstable or marginally stable, but it is not clear what is wrong if this doesn’t happen. This note shows that, for a generic Einstein quantum theory of gravity in AdS, exactly stability of extremal black branes is in tension with rigorously proven quantum information theorems about entanglement entropy. Avoiding the contradiction leads to a nonperturbative version of the WGC, which reduces to the usual statement at weak coupling. The argument is general, and it does not rely on either supersymmetry or a particular UV completion, assuming only the validity of Einsteinian gravity, effective field theory, and holography. The pathology is related to the development of an infinite throat in the near-horizon region of the extremal solutions, which suggests a connection to the ER=EPR proposal.
A
bstract
There is significant evidence suggesting that continuous global symmetries are always gauged in quantum gravity. However, very weakly gauged symmetries seem global to an effective field ...theory expansion in powers of Newton’s constant. We show that, at least for Einsteinian quantum gravity on AdS, such extremely weak gaugings are indeed in the Swampland: consistency with AdS black hole thermodynamics requires the bulk gauge coupling
g
2
not to vanish faster than ∼ exp(−
ℓ
d
−1
/G
), where
ℓ
is the
AdS
d
+1
radius and
G
is Newton’s constant as we take the
G
→ 0 limit. This translates to a constraint in the dual large
N
CFT, namely, that the two-point function coefficient of the current
C
J
cannot grow faster than exp(
N
2
) in the large
N
limit. We also recover a previously known logarithmic relationship between the cutoff of the effective field theory in AdS, Planck’s mass, and the AdS radius.
cognitive impairment is an established fall risk factor; however, it is unclear whether a disease-specific diagnosis (i.e. dementia), measures of global cognition or impairments in specific cognitive ...domains (i.e. executive function) have the greatest association with fall risk. Our objective was to evaluate the epidemiological evidence linking cognitive impairment and fall risk.
studies were identified through systematic searches of the electronic databases of MEDLINE, EMBASE, PyschINFO (1988-2009). Bibliographies of retrieved articles were also searched. A fixed-effects meta-analysis was performed using an inverse-variance method.
twenty-seven studies met the inclusion criteria. Impairment on global measures of cognition was associated with any fall, serious injuries (summary estimate of OR = 2.13 (1.56, 2.90)) and distal radius fractures in community-dwelling older adults. Executive function impairment, even subtle deficits in healthy community-dwelling older adults, was associated with an increased risk for any fall (summary estimate of OR = 1.44 (1.20, 1.73)) and falls with serious injury. A diagnosis of dementia, without specification of dementia subtype or disease severity, was associated with risk for any fall but not serious fall injury in institution-dwelling older adults.
the method used to define cognitive impairment and the type of fall outcome are both important when quantifying risk. There is strong evidence global measures of cognition are associated with serious fall-related injury, though there is no consensus on threshold values. Executive function was also associated with increased risk, which supports its inclusion in fall risk assessment especially when global measures are within normal limits.
Battery equalization active methods GALLARDO-LOZANO, Javier; ROMERO-CADAVAL, Enrique; MILANES-MONTERO, M. Isabel ...
Journal of power sources,
2014, Letnik:
246
Journal Article
Recenzirano
Many different battery technologies are available for the applications which need energy storage. New researches are being focused on Lithium-based batteries, since they are becoming the most viable ...option for portable energy storage applications. As most of the applications need series battery strings to meet voltage requirements, battery imbalance is an important matter to be taken into account, since it leads the individual battery voltages to drift apart over time, and premature cells degradation, safety hazards, and capacity reduction will occur. A large number of battery equalization methods can be found, which present different advantages/disadvantages and are suitable for different applications. The present paper presents a summary, comparison and evaluation of the different active battery equalization methods, providing a table that compares them, which is helpful to select the suitable equalization method depending on the application. By applying the same weight to the different parameters of comparison, switch capacitor and double-tiered switching capacitor have the highest ratio. Cell bypass methods are cheap and cell to cell ones are efficient. Cell to pack, pack to cell and cell to pack to cell methods present a higher cost, size, and control complexity, but relatively low voltage and current stress in high-power applications.
The rising interest in the valorisation of industrial by-products is one of the main reasons why exploring different species and optimizing the extracting conditions of collagen and gelatin has ...attracted the attention of researchers in the last decade. The most abundant sources of gelatin are pig skin, bovine hide and, pork and cattle bones, however, the industrial use of collagen or gelatin obtained from non-mammalian species is growing in importance. The classical food, photographic, cosmetic and pharmaceutical application of gelatin is based mainly on its gel-forming properties. Recently, and especially in the food industry, an increasing number of new applications have been found for gelatin in products such as emulsifiers, foaming agents, colloid stabilizers, biodegradable film-forming materials and micro-encapsulating agents, in line with the growing trend to replace synthetic agents with more natural ones. In the last decade, a large number of studies have dealt with the enzymatic hydrolysis of collagen or gelatin for the production of bioactive peptides. Besides exploring diverse types of bioactivities, of an antimicrobial, antioxidant or antihypertensive nature, studies have also focused on the effect of oral intake in both animal and human models, revealing the excellent absorption and metabolism of Hyp-containing peptides. The present work is a compilation of recent information on collagen and gelatin extraction from new sources, as well as new processing conditions and potential novel or improved applications, many of which are largely based on induced cross-linking, blending with other biopolymers or enzymatic hydrolysis.
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The construct of identity text conjoins notions of identity affirmation and literacy engagement as equally relevant to addressing causes of underachievement among low socioeconomic status, ...multilingual, and marginalized group students. Despite extensive empirical evidence supporting the impact on academic achievement of both identity affirmation and literacy engagement, these variables have been largely ignored in educational policies and instructional practices. The authors propose a framework for identifying major causes of underachievement among these three overlapping groups and for implementing evidence-based instructional responses. The framework argues that schools can respond to the devaluation of identity experienced by many students and communities by exploring instructional policies and strategies that enable students to use their emerging academic language and multilingual repertoires for powerful identityaffirming purposes. Drawing on projects involving First Nations and immigrant-background multilingual students, the authors document the profound transformations in academic, intellectual, and personal identity that multimodal identity text work is capable of engendering.
The accumulation of toxic metals and metalloids, such as cadmium (Cd), mercury (Hg), or arsenic (As), as a consequence of various anthropogenic activities, poses a serious threat to the environment ...and human health. The ability of plants to take up mineral nutrients from the soil can be exploited to develop phytoremediation technologies able to alleviate the negative impact of toxic elements in terrestrial ecosystems. However, we must select plant species or populations capable of tolerating exposure to hazardous elements. The tolerance of plant cells to toxic elements is highly dependent on glutathione (GSH) metabolism. GSH is a biothiol tripeptide that plays a fundamental dual role: first, as an antioxidant to mitigate the redox imbalance caused by toxic metal(loid) accumulation, and second as a precursor of phytochelatins (PCs), ligand peptides that limit the free ion cellular concentration of those pollutants. The sulphur assimilation pathway, synthesis of GSH, and production of PCs are tightly regulated in order to alleviate the phytotoxicity of different hazardous elements, which might induce specific stress signatures. This review provides an update on mechanisms of tolerance that depend on biothiols in plant cells exposed to toxic elements, with a particular emphasis on the Hg-triggered responses, and considering the contribution of hormones to their regulation.
Encapsulation in polymer NPs (NPs) is a well-recognized way to improve the oral bioavailability of hydrophobic and hydrophilic compounds by enhancing their solubility in aqueous medium, to protect ...them from acid and enzymatic degradation in the gastrointestinal tract, and to favour their permeability across the mucosal membranes. Nanostructures rather than larger delivery systems are also proposed to encapsulate prebiotics, probiotics and natural antimicrobial compounds, as they allow greater penetration of the mucous layer, as well as lower and longer dosages. The NPs with mucoadhesive capacity are designed specifically to increase the residence time at the intestinal absorption sites due to their ability to adhere to the intestinal mucosa. However, they should also be able to penetrate through the mucosa to reach the enterocytes or intestinal absorptive cells. By using the appropriate materials, the size and surface properties of NPs can be routed towards a particular mucus-interaction mechanism. Polymer NPs are widely employed for oral delivery applications in the pharmaceutical industry, since their surface properties are easily tunable to improve mucoadhesive capacity and mucus penetrating ability. Due to their biodegradability, biocompatibility and non-toxicity, biopolymer NPs have gained interest in recent years as mucoadhesive delivery systems for potential food applications. This review aims to promote attention to the use of food-grade biopolymer NPs to increase the bioavailability of natural compounds based on their mucoadhesive potential, and to facilitate the delivery of prebiotics, probiotics and antimicrobials along the gastrointestinal tract. This also includes a previous brief introduction to the complex mucoadhesion mechanism and common evaluation methods for determining mucoadhesiveness in nanoparticulate systems.
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•Mucoadhesive NPs enhance oral bioavailability of poorly absorbable bioactives.•Biopolymer NPs with mucoadhesive properties have potential food applications.•Surface functionalisation of biopolymer NPs may improve their mucoadhesiveness.•Proper NP formulation allows selective delivery of natural compound along GI tract.•Nanostructures are viable for encapsulating probiotics to be delivered to the colon.
Carbon dioxide can form compounds with nitrogen heterocyclic carbenes (NHCs) based on azoles through noncovalent interactions or by covalent bonding. A narrow dependence on the carbene structure has ...been observed for the preference for one or the other type of bonding, as revealed by a series of physicochemical descriptors. In our survey, a set of NHCs based on the azole family (three classical, three abnormal, and one remote) was shown to bind CO2 at the accurate G4MP2 computational level. In most cases, exothermic reaction profiles towards the covalently bound form were found, which reached stabilization enthalpies of up to −77 kJ mol−1 for the remote carbene case. Both noncovalent and covalent minima and the corresponding transition state that connects them have been identified as stationary points along the reaction coordinate.
It′s a trap! The formation of covalent bonds or noncovalent interactions between carbon dioxide and nitrogen heterocyclic carbenes (NHCs) of the azole family (see figure) has been explored theoretically at the accurate G4MP2 computational level. The stability of the covalent bond formed was found to depend on the structure of the carbine.
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