General bounds on holographic complexity

We prove a positive volume theorem for asymptotically AdS spacetimes: the maximal volume slice has nonnegative vacuum-subtracted volume, and the vacuum-subtracted volume vanishes if and only if the spacetime is identically pure AdS. Under the Complexity=Volume proposal, this constitutes a positive holographic complexity theorem. The result features a number of parallels with the positive energy theorem, including the assumption of an energy condition that excludes false vacuum decay (the AdS weak energy condition). Our proof is rigorously established in broad generality in four bulk dimensions, and we provide strong evidence in favor of a generalization to arbitrary dimensions. Our techniques also yield a holographic proof of Lloyd’s bound for a class of bulk spacetimes. We further establish a partial rigidity result for wormholes: wormholes with a given throat size are more complex than AdS-Schwarzschild with the same throat size.

The essential coexistence phenomenon in Hamiltonian dynamics

We construct an example of a Hamiltonian flow $f^t$ on a four-dimensional smooth manifold $\mathcal {M}$ which after being restricted to an energy surface $\mathcal {M}_e$ demonstrates essential coexistence of regular and chaotic dynamics, that is, there is an open and dense $f^t$ -invariant subset $U\subset \mathcal {M}_e$ such that the restriction $f^t|U$ has non-zero Lyapunov exponents in all directions (except for the direction of the flow) and is a Bernoulli flow while, on the boundary $\partial U$ , which has positive volume, all Lyapunov exponents of the system are zero.

Elastic geobarometry of quartz inclusions in garnet at high temperature

<p>Elastic geo-thermobarometry allows the retrieval of the pressure and temperature of entrapment of an inclusion within a host (Zhang, 1998; Angel et al., 2014; Angel et al., 2015). So far, quartz-in-garnet elastic geobarometry has mainly dealt with rocks with inclusions entrapped at high pressure and low temperature conditions, such as eclogite. This is because, at high-temperature (HT) and low-to-medium-pressure conditions (T > 700 °C and P < 1.0 GPa), the rock might cross the α–β quartz transition, changing the elastic properties of quartz inclusions. Here we will show some preliminary results of HT elastic geobarometry in quartz inclusions entrapped (or re-equilibrated) within the β–quartz stability field.<br>The analysed samples come from three HT-LP terranes: the Athabasca granulite terrane in Canada (Dumond et al., 2015), the Jubrique Unit in the Beltic Cordilliera in Spain (Barich et al., 2014), and the Aus granulite terrane from the Namaqua metamorphic complex in Southern Namibia (Diener et al., 2013). These terrains include crustal rocks such as garnet-bearing gneisses and felsic and mafic granulites that equilibrated at low pressures and high temperatures, near or within the β-quartz stability field. Within these samples, Cesare et al. (2020) described post-entrapment shape change of quartz inclusion in garnet. The quartz inclusions have Raman spectra with peaks shifted to lower wavenumbers with respect to the unstrained reference quartz crystal. The changes in Raman peak shifts of the inclusions were converted into strains using the software StRAinMAN (Angel et al., 2019) and have positive volume strains with ε1>0 and ε3<0. The quartz EoS by Angel et al. (2017), which includes the α–β quartz transition, allowed the entrapment isomekes crossing the phase transition to be calculated and the entrapment pressures of quartz inclusions at HT to be estimated. The results of elastic geobarometry for the set of samples in question are consistent with the PT estimates by classic geothermobarometry, suggesting entrapment or re-equilibration at HT within the β–quartz stability field.<br>This work was supported by ERC-StG TRUE DEPTHS grant (number 714936) to M. Alvaro</p><p>References<br>Angel et al. (2014) - Am. Mineral. 99, 2146-2149. Angel et al. (2015) - J. Metamorph. Geol. 33, 801-813. Angel et al. (2017) - Contrib. Mineral. Petr. 172, 29. Angel et al. (2019) - Z. Krist.-Cryst. Mater. 234, 129-140. Barich et al. (2014) - Lithos 206, 303-320. Cesare et al. (2020) - Earth Planet. Sc. Lett. 555, 116708. Diener et al. (2013) - Precambrian Res. 224, 629-652. Dumond et al. (2015) - J. Metamorph. Geol. 33, 735-762. Zhang (1998) - Earth Planet. Sc. Lett. 157, 209-222.</p>

The Mw7.1 September 19th Puebla-Morelos (Mexico) earthquake triggered by brucite and antigorite dewatering

<p>Subduction controls key geological processes at convergent margins including seismicity and resultant seismic hazard. The September 19th 2017 Mw7.1 Mexican earthquake nucleated ~250 km from the trench within the Cocos plate near its Moho, ~57 km below Earth’s surface. The prevailing hypothesis suggests that this earthquake resulted from bending stresses occurring at the flat-to-steep subduction transition. Here, we present an alternative, but not mutually exclusive, hypothesis: the dehydration reaction brucite + antigorite = olivine + H2O in the slab mantle controls intermediate-depth seismicity along the flat portion of the subducted Cocos plate. This reaction releases a substantial amount of H2O, resulting in a large positive volume change, and thus in an increase in pore fluid pressure at the appropriate depth–temperature conditions to cause the Puebla-Morelos and other intraslab earthquakes in Mexico. The amount of H2O released by this reaction depends on the degree of serpentinization of the oceanic mantle prior to subduction. Only oceanic mantle with > 60% serpentinization—as expected along abundant deep extensional faults at the mid-ocean-ridge or where the plate bends at the outer rise—will stabilize brucite, and thus, will experience this reaction at the same depths where the September 19th 2017 earthquake nucleated.</p>

Smectite-water exchanges at the Ceres crust

<p>Dawn mission sensors detected pervasive Mg and NH<sub>4</sub> phyllosilicates mixed with a dark mineral component, probably magnetite, on Ceres’ surface, and observed Na and Mg carbonates locally associated to impact structures [1-4]. Ceres’ crust is mainly composed by different phases of silicates, water and salts. Stephan et al. [5] suggest that the NH<sub>4</sub>-phyllosilicate is also one of the most representative components in the crust, while the distribution of water as ice or liquid is dependent on the depth. Recent models show that Ceres precursors and the differentiated crust have suffered aqueous alteration and porosity reduction during its evolution, in which silicates and water have physically and chemically interacted [6].</p> <p>To understand the exchanges between water and the rock particles we are performing a set of experiments simulating the thermal evolution of two systems: 1) montmorillonite clays in liquid water; 2) montmorillonite clays in brine solutions.</p> <p>NH<sub>4</sub>-montmorillonite is obtained in the laboratory by cation substitution method [7] from the montmorillonite (Gonzales County, Texas, USA) ((Na,Ca)<sub>0.33</sub>(Al,Mg)<sub>2</sub>(Si<sub>4</sub>O<sub>10</sub>)(OH)<sub>2</sub>·nH<sub>2</sub>O). The resulting smectite was checked and characterized by XRD, IR and Raman spectroscopy.</p> <p>In the first set of experiments 1.5 wt% of both, the original and the NH<sub>4</sub>-montmorillonite, were suspended in liquid water and placed into a pressure cell. In order to simulate the conditions in the ice-rich crust, systems were cooled down to 263 K for 24 hours. After that, the samples were heated up to room temperature.</p> <p>During the heating of our first tests with pure water, just when the ice started to melt at 272 K, we observed shifts from 1 to 2.8 bar in the case of the montmorillonite, and to 2.6 bar when working with the NH<sub>4</sub>-enriched clay.</p> <p>In the second set of experiments, the protocol was repeated, but the original montmorillonite was suspended in an eutectic solution of NaCl (23 wt %). It also showed a pressure shift near the eutectic temperature of the solution 251 K from 1 to 1.5 bar.</p> <p>We interpret these pressure shifts as the effect of a positive volume change of the system, in which the reduction of the water volume by melting is overcompensated by the smectite swelling, even at the low clay quantities we are using in these experiments. When the phyllosilicate freezes, the interlayer distance is reduced [8] and the molecules of water release. This effect is reversible if the clay is in an aqueous environment. The number of molecules inserted between layers depends on the cation in the clay. The Na<sup>+ </sup>present in the original montmorillonite has the capability to incorporate more than 12 molecules of water [8]. Experiments done so far with NH<sub>4</sub>-smectites suggest that its facility to swell is lower in the NH<sub>4</sub>-montmorillonite than in the original montmorillonite [9].</p> <p>From the laboratory results, we can argue that the interaction between water-smectite during thermal evolution of Ceres’ crust could yield interesting geological effects such as the clay dehydration by freezing, the precipitation of salts from brines when swelling occurs or the generation of stresses by the deformation of the materials.</p> <p><strong>References:</strong> [1] Ammannito et al., 2016. Science, 353, issue 6503 aaf4279. [2] De Sanctis et al., 2015. Nature, 528, 241-244. [3] Longobardo et al., 2017. Icarus, .318, .205-211. [4] Stein et al, 2019. Icarus, .320, 188-201. [5] Stephan et al., 2017 Icarus 318 , 111-123 [6] Neumann et al., 2020 Astronomy & Astrophysics 633, A117  [7] Gautier et al., 2010. Applied Clay Science, 49 (3), 247-254. [8] Madsen F. T. and Muller-Vonmoos. 1989 Applied clay science 4 (2), 143-156. [9] Norrish and Rausel-Colom, 1962 Clay minerals bull. 5, 9-16.</p>

Assessing the hospital volume-outcome relationship in surgery: a scoping review protocol

IntroductionEven if a positive volume-outcome correlation in surgery is mostly admitted in many surgical fields, the various ways to assess this relationship make it difficult for researchers and policymakers to use it. Our aim is therefore to provide an overview of the way hospital volume-outcome relationship was assessed. Through this overview, our goal is to identify potential gaps in the assessment of this relationship, to help researchers who want to pursue work in this field and, ultimately, to help policy makers interpret such analyses.Methods and analysisThis review will be conducted using the six stages of the scoping review method: identifying the research question, searching for relevant studies, selecting studies, data extraction, collating, summarising and reporting the results and concluding. This review will address all the key questions used to assess the volume-outcome relationship in surgery.Primary research papers investigating the hospital volume-outcome relationship from 2009 will be included. Studies only looking at surgeons’ volume-outcome relationship or studies were the volume variable is not individualisable will be excluded.Both MEDLINE and Scopus will be searched along with grey literature. Two researchers will perform all the stages of the review: screen the titles and abstracts, review the full text of selected articles to determine final inclusions and extract the data. The results will be summarised quantitatively using numerical counts.Ethical considerations and disseminationReviews of published articles are considered secondary analysis and do not need ethical approval. The findings will be disseminated through multiple channels like conferences and peer-reviewed journals.

Investor attention and market correction

PurposeThis study disentangles the investor-base effect and the information effect of investor attention. The former leads to a larger investor base and higher stock returns, while the latter facilitates the dissemination of information among investors and impacts informational trading.Design/methodology/approachUsing positive volume shocks as a proxy for increased investor attention, this study evaluates the impacts of the investor-base effect and the information effect of investor attention on market correction following extreme daily returns in the US stock market from 1966 to 2018.FindingsThis study finds that the investor-base effect increases subsequent returns of both daily winner and daily loser stocks. The information effect leads to economically less significant return reversals for both the daily winner and daily loser stocks. These two effects tend to have economically more significant impacts on the daily loser stocks. The economic significance of these two effects is also related to firm size and the state of the stock market.Originality/valueThis study is the first to disentangle the investor-base effect and the information effect of increased investor attention. The evidence that the information effect facilitates the dissemination of new information and impacts stock returns contributes to the strand of studies on the impact of investor attention on market efficiency. This evidence also contributes to the strand of studies analyzing the impact of informational trading on stock returns. In addition, this study provides evidence for market overreaction and the subsequent correction. The results for up and down markets contribute to the literature on the investors' trading behavior.

Statistical properties for compositions of standard maps with increasing coefficient

The Chirikov standard map is a prototypical example of a one-parameter family of volume-preserving maps for which one anticipates chaotic behavior on a non-negligible (positive-volume) subset of phase space for a large set of parameters. Rigorous analysis is notoriously difficult and it remains an open question whether this chaotic region, the stochastic sea, has positive Lebesgue measure for any parameter value. Here we study a problem of intermediate difficulty: compositions of standard maps with increasing coefficient. When the coefficients increase to infinity at a sufficiently fast polynomial rate, we obtain a strong law, a central limit theorem, and quantitative mixing estimates for Holder observables. The methods used are not specific to the standard map and apply to a class of compositions of ‘prototypical’ two-dimensional maps with hyperbolicity on ‘most’ of phase space.

Dynamical spatial curvature as a fit to Type Ia supernovae

Few statements in cosmology can be made without assuming a cosmological model within which to interpret data. Statements about cosmic acceleration are no exception to this rule, and the inferred positive volume acceleration of our universe often quoted in the literature is valid in the context of the standard Friedmann–Lemaître–Robertson–Walker (FLRW) class of spacetimes. Using the Joint Light-curve Analysis (JLA) catalogue of supernovae Type Ia (SNIa), we examine the fit of a class of exact scaling solutions with dynamical spatial curvature formulated in the framework of a scalar averaging scheme for relativistic inhomogeneous spacetimes. In these models, global volume acceleration may emerge as a result of the nonlocal variance between expansion rates of clusters and voids, the latter gaining volume dominance in the late-epoch universe. We find best-fit parameters for a scaling model of backreaction that are reasonably consistent with previously found constraints from SNIa, CMB, and baryon acoustic oscillations data. The quality of fit of the scaling solutions is indistinguishable from that of the ΛCDM model and the timescape cosmology from an Akaike Information Criterion (AIC) perspective. This indicates that a broad class of models can account for the [Formula: see text] expansion history.

The Roles of Hypoxia Imaging Using 18F-Fluoromisonidazole Positron Emission Tomography in Glioma Treatment

Glioma is the most common malignant brain tumor. Hypoxia is closely related to the malignancy of gliomas, and positron emission tomography (PET) can noninvasively visualize the degree and the expansion of hypoxia. Currently, 18F-fluoromisonidazole (FMISO) is the most common radiotracer for hypoxia imaging. The clinical usefulness of FMISO PET has been established; it can distinguish glioblastomas from lower-grade gliomas and can predict the microenvironment of a tumor, including necrosis, vascularization, and permeability. FMISO PET provides prognostic information, including survival and treatment response information. Because hypoxia decreases a tumor’s sensitivity to radiation therapy, dose escalation to an FMISO-positive volume is an attractive strategy. Although this idea is not new, an insufficient amount of evidence has been obtained regarding this concept. New tracers for hypoxia imaging such as 18F-DiFA are being tested. In the future, hypoxia imaging will play an important role in glioma management.