Fundamental physical cellular constraints drive self-organization of tissues

Morphogenesis is driven by small cell shape changes that modulate tissue organization. Apical surfaces of proliferating epithelial sheets have been particularly well studied. Currently, it is accepted that a stereotyped distribution of cellular polygons is conserved in proliferating tissues among metazoans. In this work, we challenge these previous findings showing that diverse natural packed tissues have very different polygon distributions. We use Voronoi tessellations as a mathematical framework that predicts this diversity. We demonstrate that Voronoi tessellations and the very different tissues analysed share an overriding restriction: the frequency of polygon types correlates with the distribution of cell areas. By altering the balance of tensions and pressures within the packed tissues using disease, genetic or computer model perturbations, we show that as long as packed cells present a balance of forces within tissue, they will be under a physical constraint that limits its organization. Our discoveries establish a new framework to understand tissue architecture in development and disease. Synopsis Cell shapes in naturally packed tissues have different polygon distributions. Voronoi tessellations-based analysis suggests that polygon frequencies are restricted by the distribution of cell areas, and that this restriction emanates from the balance of forces within the tissue. Cell shapes in natural packed tissues present very different polygon distributions. These patterns can be reproduced by Voronoi tessellations. Natural tissues and Voronoi diagrams share some geometrical properties. There is a physical constraint that limits the organization of natural tissues. Unbalance of forces within the natural tissue breaks this restriction. Cell shapes in naturally packed tissues have different polygon distributions. Voronoi tessellations-based analysis suggests that polygon frequencies are restricted by the distribution of cell areas, and that this restriction emanates from the balance of forces within the tissue.Ministerio de Ciencia e Innovación BFU2011-2573

Exploring the self-assembly and energy transfer of dynamic supramolecular iridium-porphyrin systems

EZ-C acknowledges the University of St Andrews for financial support. IDWS acknowledges support from EPSRC (EP/J009016) and the European Research Council (grant 321305). IDWS also acknowledges support from a Royal Society Wolfson research merit award. DJ acknowledges the European Research Council (grant: 278845) and the RFI Lumomat for financial support.We present the first examples of dynamic supramolecular systems composed of cyclometalated Ir(III) complexes of the form of [Ir(C^N)2(N^N)]PF6 (where C^N is mesppy = 2-phenyl-4-mesitylpyridinato and dFmesppy = 2-(4,6-difluorophenyl)-4-mesitylpyridinato and N^N is 4,4':2',2'':4'',4'''-quaterpyridine, qpy) and zinc tetraphenylporphyrin (ZnTPP), assembled through non-covalent interactions between the distal pyridine moieties of the qpy ligand located on the iridium complex and the zinc of the ZnTPP. The assemblies have been comprehensively characterized by a series of analytical techniques (1H NMR titration experiments, 2D COSY and HETCOR NMR spectra and low temperature 1H NMR spectroscopy) and the crystal structures have been elucidated by X-ray diffraction. The optoelectronic properties of the assemblies and the electronic interaction between the iridium and porphyrin chromophoric units have been explored with detailed photophysical measurements, supported by time-dependent density functional theory (TD-DFT) calculations.PostprintPeer reviewe

Vector commitments over rings and compressed Σ-protocols

Compressed Σ-Protocol Theory (CRYPTO 2020) presents an “alternative” to Bulletproofs that achieves the same communication complexity while adhering more elegantly to existing Σ -protocol theory, which enables their techniques to be directly applicable to other widely used settings in the context of “plug & play” algorithmics. Unfortunately, their techniques are restricted to arithmetic circuits over prime fields, which rules out the possibility of using more machine-friendly moduli such as powers of 2, which have proven to improve efficiency in applications. In this work we show that such techniques can be generalized to the case of arithmetic circuits modulo any number. This enables the use of powers of 2, which can prove to be beneficial for efficiency, but it also facilitates the use of other moduli that might prove useful in different applications. In order to achieve this, we first present an instantiation of the main building block of the theory of compressed Σ -protocols, namely compact vector commitments. Our construction, which may be of independent interest, is homomorphic modulo any positive integer m, a result that was not known in the literature before. Second, we generalize Compressed Σ-Protocol Theory from finite fields to Zm. The main challenge here is ensuring that there are large enough challenge sets as to fulfill the necessary soundness requirements, which is achieved by considering certain ring extensions. Our techniques have direct application for example to verifiable computation on homomorphically encrypted data

Asymptotically Good Multiplicative LSSS over Galois Rings and Applications to MPC over Z/ pkZ

We study information-theoretic multiparty computation (MPC) protocols over rings Z/ pkZ that have good asymptotic communication complexity for a large number of players. An important ingredient for such protocols is arithmetic secret sharing, i.e., linear secret-sharing schemes with multiplicative properties. The standard way to obtain these over fields is with a family of linear codes C, such that C, C⊥ and C2 are asymptotically good (strongly multiplicative). For our purposes here it suffices if the square code C2 is not the whole space, i.e., has codimension at least 1 (multiplicative). Our approach is to lift such a family of codes defined over a finite field F to a Galois ring, which is a local ring that has F as its residue field and that contains Z/ pkZ as a subring, and thus enables arithmetic that is compatible with both structures. Although arbitrary lifts preserve the distance and dual distance of a code, as we demonstrate with a counterexample, the multiplicative property is not preserved. We work around this issue by showing a dedicated lift that preserves self-orthogonality (as well as distance and dual distance), for p≥ 3. Self-orthogonal codes are multiplicative, therefore we can use existing results of asymptotically good self-dual codes over fields to obtain arithmetic secret sharing over Galois rings. For p= 2 we obtain multiplicativity by using existing techniques of secret-sharing using both C and C⊥, incurring a constant overhead. As a result, we obtain asymptotically good arithmetic secret-sharing schemes over Galois rings. With these schemes in hand, we extend existing field-based MPC protocols to obtain MPC over Z/ pkZ, in the setting of a submaximal adversary corrupting less than a fraction 1 / 2 - ε of the players, where ε> 0 is arbitrarily small. We consider 3 different corruption models. For passive and active security with abort, our protocols communicate O(n) bits per multiplication. For full security with guaranteed output delivery we use a preprocessing model and get O(n) bits per multiplication in the online phase and O(nlog n) bits per multiplication in the offline phase. Thus, we obtain true linear bit complexities, without the common assumption that the ring size depends on the number of players

Quantitative Evaluation of Artifact Removal in Real Magnetoencephalogram Signals with Blind Source Separation

The magnetoencephalogram (MEG) is contaminated with undesired signals, which are called artifacts. Some of the most important ones are the cardiac and the ocular artifacts (CA and OA, respectively), and the power line noise (PLN). Blind source separation (BSS) has been used to reduce the influence of the artifacts in the data. There is a plethora of BSS-based artifact removal approaches, but few comparative analyses. In this study, MEG background activity from 26 subjects was processed with five widespread BSS (AMUSE, SOBI, JADE, extended Infomax, and FastICA) and one constrained BSS (cBSS) techniques. Then, the ability of several combinations of BSS algorithm, epoch length, and artifact detection metric to automatically reduce the CA, OA, and PLN were quantified with objective criteria. The results pinpointed to cBSS as a very suitable approach to remove the CA. Additionally, a combination of AMUSE or SOBI and artifact detection metrics based on entropy or power criteria decreased the OA. Finally, the PLN was reduced by means of a spectral metric. These findings confirm the utility of BSS to help in the artifact removal for MEG background activity

Surfactant-Free Colloidal Syntheses of Gold-Based Nanomaterials in Alkaline Water and Mono-alcohol Mixtures [Dataset]

120 pages. -- SA. Synthesis of Au NPs using ROH. -- SB. Experimental section. -- SC. Effect of mono-alcohol, mono-alcohol content and cation. -- SD. Effect of experimental parameters: HAuCl4 concentration, volume of solution, type of container used, light. -- SE. Effect of the nature of the alcohols. -- SF. Kinetics of the reduction. -- SG. Influence of the temperature. -- SH. Influence of base concentration. -- SI. Influence of gas atmosphere. -- SJ. Influence of the order of addition of the chemicals. -- SK. Discussion of Au NP formation. -- SL. Reproducibility. -- SM. Scalability. -- SN. Mixture of mono-alcohols. -- SO. Cation and surfactant effects . -- SP. Electrochemical characterization of Au NPs. -- SQ. Supported NPs. -- SR. Pd and bimetallic NPs. -- SS. Nanocomposites. -- ST. Electrochemical characterization of AuxPdy NPs and [x Au + y Pd] nanocomposites. -- SU. Outlook into multi-metallic nanomaterials. -- SV. Comparison of different catalysts. -- SW. ReferencesGold nanoparticles (Au NPs) and gold-based nanomaterials combine unique properties relevant for medicine, imaging, optics, sensing, catalysis, and energy conversion. While the Turkevich–Frens and Brust–Schiffrin methods remain the state-of-the-art colloidal syntheses of Au NPs, there is a need for more sustainable and tractable synthetic strategies leading to new model systems. In particular, stabilizers are almost systematically used in colloidal syntheses, but they can be detrimental for fundamental and applied studies. Here, a surfactant-free synthesis of size-controlled colloidal Au NPs stable for months is achieved by the simple reduction of HAuCl4 at room temperature in alkaline solutions of low-viscosity mono-alcohols such as ethanol or methanol and water, without the need for any other additives. Palladium (Pd) and bimetallic AuxPdy NPs, nanocomposites and multimetallic samples, are also obtained and are readily active (electro)­catalysts. The multiple benefits over the state-of-the-art syntheses that this simple synthesis bears for fundamental and applied research are highlighted.Peer reviewe

The Higgs sector of the munuSSM and collider physics

The $\mu\nu$SSM is a supersymmetric standard model that accounts for light neutrino masses and solves the $\mu$ problem of the MSSM by simply using right-handed neutrino superfields. Since this mechanism breaks R-parity, a peculiar structure for the mass matrices is generated. The neutral Higgses are mixed with the right- and left-handed sneutrinos producing 8$\times$8 neutral scalar mass matrices. We analyse the Higgs sector of the $\mu\nu$SSM in detail, with special emphasis in possible signals at colliders. After studying in general the decays of the Higges, we focus on those processes that are genuine of the $\mu\nu$SSM, and could serve to distinguish it from other supersymmetric models. In particular, we present viable benchmark points for LHC searches. For example, we find decays of a MSSM-like Higgs into two lightest neutralinos, with the latter decaying inside the detector leading to displaced vertices, and producing final states with 4 and 8 $b$-jets plus missing energy. Final states with leptons and missing energy are also found.Comment: Final version to appear in JHEP. The discussion on signals at colliders, expanded. 33 pages, 8 figures and 9 table

The Impact of Culturing the Organ Preservation Fluid on Solid Organ Transplantation: A Prospective Multicenter Cohort Study

Background. We analyzed the prevalence, etiology, and risk factors of culture-positive preservation fluid and their impact on the management of solid organ transplant recipients. Methods. From July 2015 to March 2017, 622 episodes of adult solid organ transplants at 7 university hospitals in Spain were prospectively included in the study. Results. The prevalence of culture-positive preservation fluid was 62.5% (389/622). Nevertheless, in only 25.2% (98/389) of the cases were the isolates considered ?high risk? for pathogenicity. After applying a multivariate regression analysis, advanced donor age was the main associated factor for having culture-positive preservation fluid for high-risk microorganisms. Preemptive antibiotic therapy was given to 19.8% (77/389) of the cases. The incidence rate of preservation fluid?related infection was 1.3% (5 recipients); none of these patients had received preemptive therapy. Solid organ transplant (SOT) recipients with high-risk culture-positive preservation fluid receiving preemptive antibiotic therapy presented both a lower cumulative incidence of infection and a lower rate of acute rejection and graft loss compared with those who did not have high-risk culture-positive preservation fluid. After adjusting for age, sex, type of transplant, and prior graft rejection, preemptive antibiotic therapy remained a significant protective factor for 90-day infection. Conclusions. The routine culture of preservation fluid may be considered a tool that provides information about the contamination of the transplanted organ. Preemptive therapy for SOT recipients with high-risk culture-positive preservation fluid may be useful to avoid preservation fluid?related infections and improve the outcomes of infection, graft loss, and graft rejection in transplant patients

Grain and seed protein functionality

Editado por Jiménez-López, José Carlos (CSIC