Refining the prediction for OJ 287 next impact flare arrival epoch

The bright blazar OJ~287 routinely parades high brightness bremsstrahlung flares which are explained as being a result of a secondary supermassive black hole (SMBH) impacting the accretion disk of a primary SMBH in a binary system. We begin by showing that these flares occur at times predicted by a simple analytical formula, based on the Kepler equation, which explains flares since 1888. The next impact flare, namely the flare number 26, is rather peculiar as it breaks the typical pattern of two impact flares per 12 year cycle. This will be the third bremsstrahlung flare of the current cycle that follows the already observed 2015 and 2019 impact flares from OJ~287. Unfortunately, astrophysical considerations make it difficult to predict the exact arrival epoch of the flare number 26. In the second part of the paper, we describe our recent OJ~287 observations. They show that the pre-flare light curve of flare number 22, observed in 2005, exhibits similar activity as the pre-flare light curve in 2022, preceding the expected flare number 26 in our model. We argue that the pre-flare activity most likely arises in the primary jet whose activity is modulated by the transit of the secondary SMBH through the accretion disk of the primary. Observing the next impact flare of OJ~287 in October 2022 will substantiate the theory of disk impacts in binary black hole systems.Comment: 16 pages, 2 figure

Negation and the functional sequence

There exists a general restriction on admissible functional sequences which prevents adjacent identical heads. We investigate a particular instantiation of this restriction in the domain of negation. Empirically, it manifests itself as a restriction the stacking of multiple negative morphemes. We propose a principled account of this restriction in terms of the general ban on immediately consecutive identical heads in the functional sequence on the one hand, and the presence of a Neg feature inside negative morphemes on the other hand. The account predicts that the stacking of multiple negative morphemes should be possible provided they are separated by intervening levels of structure. We show that this prediction is borne out

State selective study of H 3

Rate coefficients for nuclear spin state-specific recombination of H3+ ions with thermal electrons were measured using FALP and SA techniques at temperatures 77–300 K. For this purpose H2 gas with both thermal and enriched population of the para nuclear spin configuration was used. Measurements have shown that at 77 K para-H3+ exhibits five times higher binary recombination rate coefficient than ortho-H3+: (1.5 ± 0.4) × 10−7 vs. (3 ± 2) × 10−8 cm3s−1

Macromolecular condensation buffers intracellular water potential.

Acknowledgements: The order of the second and corresponding authors is arbitrary and these authors can change the order of their respective names to suit their own interests. This work has been supported by the Medical Research Council, as part of United Kingdom Research and Innovation (MC_UP_1201/13 to E.D.; MC_UP_1201/4 to J.S.O. and MCMB MR/V028669/1 to J.E.C.), the Human Frontier Science Program (Career Development Award CDA00034/2017 to E.D.), a Versus Arthritis Senior Research Fellowship Award (20875 to Q.-J.M.) and an MRC project grant (MR/K019392/1 to Q.-J.M.), a Grifols ‘ALTA’ Alpha-1-Antitrypsin Laurell’s Training Award and an Alpha-1-Foundation (grant number 614939) to J.E.C., and by a Wellcome Trust Sir Henry Dale Fellowship (208790/Z/17/Z to R.S.E.). N.M.R. is supported by a Medical Research Council Clinician Scientist Fellowship (MR/S022023/1). L.K.K. and V.J.P.-H. are recipients of EMBO Postdoctoral fellowships (ALTF 876-2021 and ALTF 577-2018, respectively). K.E.M. is supported by the Wellcome Trust through a Sir Henry Wellcome Postdoctoral Fellowship (220480/Z/20/Z). P.M.M. and J.B. were supported by Volkswagen ‘Life’ grant number 96827 and the DFG Excellence Cluster Physics of Life. We thank H. Andreas for frog maintenance; C. Godlee and M. Kaksonen for the gift of unpublished S. cerevisiae yeast strains and initial discussion of yeast experiments about temperature; P. Tran for S. pombe yeast strains; L. Miller for help with yeast work; A. Bertolotti for the kind gift of SH-SY5Y cells; and C. Russo, F. Jülicher, M. Gonzalez-Gaitan, K. Kruse, L. Blanchoin, J. Löwe, R. Hegde, P. Farrell and P. Crosby for discussion and suggestions; the staff at the companies Cherry Biotech and Elvesys, in particular T. Guérinier, for their help in designing and assembling the custom microfluidics system required for this project; the members of the Electronics and Mechanical workshops of the LMB for key support; the staff at the LMB Mass Spectrometry facility for performing and analysing MS data; and A. Prasad and T. Stevens for sharing the scripts for protein disorder and kinase motif predictions, respectively. Cartoons were created using BioRender. For the purpose of open access, the MRC Laboratory of Molecular Biology has applied a CC BY public copyright licence to any author accepted manuscript version arising.Optimum protein function and biochemical activity critically depends on water availability because solvent thermodynamics drive protein folding and macromolecular interactions1. Reciprocally, macromolecules restrict the movement of 'structured' water molecules within their hydration layers, reducing the available 'free' bulk solvent and therefore the total thermodynamic potential energy of water, or water potential. Here, within concentrated macromolecular solutions such as the cytosol, we found that modest changes in temperature greatly affect the water potential, and are counteracted by opposing changes in osmotic strength. This duality of temperature and osmotic strength enables simple manipulations of solvent thermodynamics to prevent cell death after extreme cold or heat shock. Physiologically, cells must sustain their activity against fluctuating temperature, pressure and osmotic strength, which impact water availability within seconds. Yet, established mechanisms of water homeostasis act over much slower timescales2,3; we therefore postulated the existence of a rapid compensatory response. We find that this function is performed by water potential-driven changes in macromolecular assembly, particularly biomolecular condensation of intrinsically disordered proteins. The formation and dissolution of biomolecular condensates liberates and captures free water, respectively, quickly counteracting thermal or osmotic perturbations of water potential, which is consequently robustly buffered in the cytoplasm. Our results indicate that biomolecular condensation constitutes an intrinsic biophysical feedback response that rapidly compensates for intracellular osmotic and thermal fluctuations. We suggest that preserving water availability within the concentrated cytosol is an overlooked evolutionary driver of protein (dis)order and function

Macromolecular condensation buffers intracellular water potential

Acknowledgements: The order of the second and corresponding authors is arbitrary and these authors can change the order of their respective names to suit their own interests. This work has been supported by the Medical Research Council, as part of United Kingdom Research and Innovation (MC_UP_1201/13 to E.D.; MC_UP_1201/4 to J.S.O. and MCMB MR/V028669/1 to J.E.C.), the Human Frontier Science Program (Career Development Award CDA00034/2017 to E.D.), a Versus Arthritis Senior Research Fellowship Award (20875 to Q.-J.M.) and an MRC project grant (MR/K019392/1 to Q.-J.M.), a Grifols ‘ALTA’ Alpha-1-Antitrypsin Laurell’s Training Award and an Alpha-1-Foundation (grant number 614939) to J.E.C., and by a Wellcome Trust Sir Henry Dale Fellowship (208790/Z/17/Z to R.S.E.). N.M.R. is supported by a Medical Research Council Clinician Scientist Fellowship (MR/S022023/1). L.K.K. and V.J.P.-H. are recipients of EMBO Postdoctoral fellowships (ALTF 876-2021 and ALTF 577-2018, respectively). K.E.M. is supported by the Wellcome Trust through a Sir Henry Wellcome Postdoctoral Fellowship (220480/Z/20/Z). P.M.M. and J.B. were supported by Volkswagen ‘Life’ grant number 96827 and the DFG Excellence Cluster Physics of Life. We thank H. Andreas for frog maintenance; C. Godlee and M. Kaksonen for the gift of unpublished S. cerevisiae yeast strains and initial discussion of yeast experiments about temperature; P. Tran for S. pombe yeast strains; L. Miller for help with yeast work; A. Bertolotti for the kind gift of SH-SY5Y cells; and C. Russo, F. Jülicher, M. Gonzalez-Gaitan, K. Kruse, L. Blanchoin, J. Löwe, R. Hegde, P. Farrell and P. Crosby for discussion and suggestions; the staff at the companies Cherry Biotech and Elvesys, in particular T. Guérinier, for their help in designing and assembling the custom microfluidics system required for this project; the members of the Electronics and Mechanical workshops of the LMB for key support; the staff at the LMB Mass Spectrometry facility for performing and analysing MS data; and A. Prasad and T. Stevens for sharing the scripts for protein disorder and kinase motif predictions, respectively. Cartoons were created using BioRender. For the purpose of open access, the MRC Laboratory of Molecular Biology has applied a CC BY public copyright licence to any author accepted manuscript version arising.Optimum protein function and biochemical activity critically depends on water availability because solvent thermodynamics drive protein folding and macromolecular interactions1. Reciprocally, macromolecules restrict the movement of ‘structured’ water molecules within their hydration layers, reducing the available ‘free’ bulk solvent and therefore the total thermodynamic potential energy of water, or water potential. Here, within concentrated macromolecular solutions such as the cytosol, we found that modest changes in temperature greatly affect the water potential, and are counteracted by opposing changes in osmotic strength. This duality of temperature and osmotic strength enables simple manipulations of solvent thermodynamics to prevent cell death after extreme cold or heat shock. Physiologically, cells must sustain their activity against fluctuating temperature, pressure and osmotic strength, which impact water availability within seconds. Yet, established mechanisms of water homeostasis act over much slower timescales2, 3; we therefore postulated the existence of a rapid compensatory response. We find that this function is performed by water potential-driven changes in macromolecular assembly, particularly biomolecular condensation of intrinsically disordered proteins. The formation and dissolution of biomolecular condensates liberates and captures free water, respectively, quickly counteracting thermal or osmotic perturbations of water potential, which is consequently robustly buffered in the cytoplasm. Our results indicate that biomolecular condensation constitutes an intrinsic biophysical feedback response that rapidly compensates for intracellular osmotic and thermal fluctuations. We suggest that preserving water availability within the concentrated cytosol is an overlooked evolutionary driver of protein (dis)order and function