Cosmic voids and filaments from quantum gravity

Using computer simulations, we study the geometry of a typical quantum universe, i.e., the geometry one might expect before a possible period of inflation. We display it using coordinates defined by means of four classical scalar fields satisfying the Laplace equation with nontrivial boundary conditions. They are a close analogue of the harmonic coordinate condition used in the context of GR (Kuchar and Torre in Phys Rev D 43:419–441, 1991). It is highly nontrivial that these ideas can be applied to understand the structures which appear in very irregular and fluctuating geometries. The field configurations reveal cosmic web structures surprisingly similar to the ones observed in the present-day universe.

New machine learning based method for identifying objects in biomedical images obtained by photon counting detectors.

The article discusses a new approach to the problem of recognition, or rather the identification of objects by the shape of their intensity in images formed by photon counting detectors or those close to them. The main problem analyzed within the framework of the approach proposed is related to the quantitative estimation of similarity between the form of radiation intensity of the object in the image and the forms of intensity of previously observed objects (precedents), providing that all of them are given by the registered sets of discrete photocounts (~ photons). It is shown that when the intensity shape is approximated by a mixture of components of an exponential family, for the implementation of the approach proposed in this work a recurrent PM algorithm for estimating the parameters of the intensity shape from a finite sample of counts associated with radiation can be synthesized. The PM algorithm turns out to be a close analogue of the well-known K-means algorithm, which is one of the most popular in the field of machine (statistical) learning. The main features of the method and its implementation are illustrated by the example of applying the method to the problem of image fragments identification for the COVID ‒ CT ‒ Dataset database.

Richard Baxter, Thomas Barlow and the Advice to a Young Student in Theology, St John's College, Cambridge, MS K.38: A Preliminary Assessment

This article identifies as the work of Richard Baxter a set of ecclesiastical directions and reading recommendations contained in fos 180–208 of St John's College, Cambridge, MS K.38, once tentatively ascribed to Thomas Barlow, but demonstrably a close analogue of British Library, MS Harleian 6009, which is a copy of a lost Baxter original. Internal evidence of MS K.38 and comparison with MS 6009 and Baxter's Christian directory imply both an earlier date and a wider circulation of Baxter's archetype than hitherto suspected, suggesting a new direction of inquiry into Baxter's scholarly and ecclesiastical associations.

STABILITY OF AFFINE G-VARIETIES AND IRREDUCIBILITY IN REDUCTIVE GROUPS

Let G be a reductive affine algebraic group and let X be an affine algebraic G-variety. We establish a (poly)stability criterion for points x ∈ X in terms of intrinsically defined closed subgroups Hx of G and relate it with the numerical criterion of Mumford and with Richardson and Bate–Martin–Röhrle criteria, in the case X = GN. Our criterion builds on a close analogue of a theorem of Mundet and Schmitt on polystability and allows the generalization to the algebraic group setting of results of Johnson–Millson and Sikora about complex representation varieties of finitely presented groups. By well established results, it also provides a restatement of the non-abelian Hodge theorem in terms of stability notions.

‘Whatever turns you on’: a response to Anna Machin, ‘Why handaxes just aren't that sexy’

Evaluating theories and testing hypotheses that relate to the no-longer observable behaviour of hominin species which have no close analogue in the modern world is an obvious challenge. Machin argues that Kohn & Mithen (1999) did not do so in a sufficiently rigorous manner concerning their so-called 'Sexy Handaxe Theory' (SHT). She is right, of course. Indeed how could it be otherwise when there is always room for improvement by subjecting previously published ideas to newly available data-sets and new types of critical thinking. Machin provides some valuable arguments, bringing together a probably unparalleled breadth of knowledge about the archaeological record, evolutionary theory and sexual selection. Ultimately, however, I am not persuaded that she makes handaxes any less sexy than they had previously appeared.

Fecundity and lifespan manipulations in Caenorhabditis elegans using exogenous peptides

In this study using Caenorhabditis elegans, we have been able to suppress (>60%) and enhance (>40%) fecundity (number of offspring) while extending lifespan by a fifth, by administering synthetic peptides to the aqueous medium in which the nematodes were maintained. Untreated control adults fed live bacteria had significantly more offspring (17 vs 10 larvae each) than those fed dead bacteria. Average lifespan and time for 50% of the worms to die were the same at approximately 10 days, but there was a significant difference in terms of 100% mortality (28 vs 19 days). A reduction in fecundity of 30-40% occurred when a 14-mer peptide, EPL030, was administered to the worms' aqueous medium. The effect was dose-dependent across the range 0.1-10 μM day–1 of medium, but since the worms were fed live bacteria interpretation was problematic: was the effect direct or indirect? However, the anti-fecundity effect was reproduced in worms fed dead bacteria, when the test compound was administered at 1 μM day–1 of aqueous medium. The mean number of larvae produced in three groups: untreated controls, EPL030 and EPL001 (an anagrammatical version of EPL030 used as a comparator), were, respectively, 17, 6 (−64%) and 24 (+43%). Average lifespans were 8.7, 10.7 (+23%) and 10.3 days (+18%). Fluorescence localisation studies using a close analogue of the fecundity-suppressing EPL030 revealed a distribution that was generalised and uninformative. The fecundity-enhancing EPL001 concentrated in the genital tract. Caenorhabditis elegans is a potentially useful testbed for fecundity and lifespan studies using exogenous agents. The use of an aqueous medium and dead bacteria as food simplifies both the protocol and interpretation of results.

Anion effects in the formation of the active catalyst in the Ruhrchemie – Rhône-Poulenc aqueous biphasic hydroformylation process. Are there any?

The water soluble [Rh(OAc)(CO)(mtppms)2] containing monosulfonated triphenylphosphine ligands was prepared for the first time and its hydrogenation was studied in aqueous solutions. In the presence of additional mtppms, the reaction yielded [RhH(CO)(mtppms)3], a close analogue of [RhH(CO)(mtppts)3], the immediate catalyst precursor in the Ruhrchemie – Rhône-Poulenc aqueous biphasic hydroformylation process. The extent of the [Rh(OAc)(CO)(mtppms)2] → [RhH(CO)(mtppms)3] transformation strongly depended on the solution pH, similar to the case of the hydrogenation of [RhCl(CO)(mtppms)2] studied earlier. In this respect, RhCl3·aq and Rh(OAc)3·aq can be used equally well for the in situ preformation of [RhH(CO)(mtppts)3], although the latter is the preferred choice in the industrial process.Key words: rhodium, water-soluble, hydrides, sulfonated phosphines, biphasic.