Search

Self-renewal is a crucial property of glioblastoma cells that is enabled by the choreographed functions of chromatin regulators and transcription factors. Identifying targetable epigenetic mechanisms of self-renewal could therefore represent an important step toward developing effective treatments for this universally lethal cancer. Here we uncover an epigenetic axis of self-renewal mediated by the histone variant macroH2A2. With omics and functional assays deploying patient-derived in vitro and in vivo models, we show that macroH2A2 shapes chromatin accessibility at enhancer elements to antagonize transcriptional programs of self-renewal. macroH2A2 also sensitizes cells to small molecule-mediated cell death via activation of a viral mimicry response. Consistent with these results, our analyses of clinical cohorts indicate that high transcriptional levels of this histone variant are associated with better prognosis of high-grade glioma patients. Our results reveal a targetable epigenetic mechanism of self-renewal controlled by macroH2A2 and suggest additional treatment approaches for glioblastoma patients.

SUMMARYSequential dengue virus (DENV) infections often generate neutralizing antibodies against all four DENV serotypes and sometimes, Zika virus. Characterizing cross-flavivirus broadly neutralizing antibody (bnAb) responses can inform countermeasure strategies that avoid infection enhancement associated with non-neutralizing antibodies. Here, we used single cell transcriptomics to mine the bnAb repertoire following secondary DENV infection. We identified several new bnAbs with comparable or superior breadth and potency to known bnAbs, and with distinct recognition determinants. Unlike all known flavivirus bnAbs, which are IgG1, one newly identified cross-flavivirus bnAb (F25.S02) was derived from IgA1. Both IgG1 and IgA1 versions of F25.S02 and known bnAbs displayed neutralizing activity, but only IgG1 enhanced infection in monocytes expressing IgG and IgA Fc receptors. Moreover, IgG-mediated enhancement of infection was inhibited by IgA1 versions of bnAbs. We demonstrate a role for IgA in flavivirus infection and immunity with implications for vaccine and therapeutic strategies.

International audience; Applications of two-dimensional (2D) perovskites have significantly outpaced the understanding of many fundamental aspects of their photophysics. The optical response of 2D lead halide perovskites is dominated by strongly bound excitonic states. However, a comprehensive experimental verification of the exciton fine structure splitting and associated transition symmetries remains elusive. Here we employ low temperature magneto-optical spectroscopy to reveal the exciton fine structure of (PEA)2PbI4 (here PEA is phenylethylammonium) single crystals. We observe two orthogonally polarized bright in-plane free exciton (FX) states, both accompanied by a manifold of phonon-dressed states that preserve the polarization of the corresponding FX state. Introducing a magnetic field perpendicular to the 2D plane, we resolve the lowest energy dark exciton state, which although theoretically predicted, has systematically escaped experimental observation (in Faraday configuration) until now. These results corroborate standard multiband, effective-mass theories for the exciton fine structure in 2D perovskites and provide valuable quantification of the fine structure splitting in (PEA)2PbI4.

The principle of maximum entropy, developed more than six decades ago, provides a systematic approach to modeling inference, and data analysis grounded in the principles of information theory, Bayesian probability and constrained optimization. Since its formulation, criticisms about the consistency of that method and the role of constraints have been raised. Among these, the chief criticism is that maximum entropy does not satisfy the principle of causation, or similarly, that maximum entropy updating is inconsistent due to an inadequate representation of causal information. We show that these criticisms rest on misunderstanding and misapplication of the way constraints have to be specified within the maximum entropy method. Correction of these problems eliminates the seeming paradoxes and inconsistencies critics claim to have detected. We demonstrate that properly formulated maximum entropy models satisfy the principle of causation.

The reactions of bicyclic divinyl ketones display wavelength-dependent changes in product formation. UV irradiation results in the formation of competitive [6,3,5] and [7,3,5] tricyclic unsaturated ketones that subsequently undergo ring expansion and reaction with a range of nucleophiles. DFT calculations and transient absorption experiments were completed that are consistent with a vinylogous Type II Norrish pathway.

I present the results of an analytic and modelling study of X-ray pulsar emission. Satellite X-ray observations of the binary pulsars GX 1+4 and RX J0812.4-3114 made using the Rossi X-ray Timing Explorer (RXTE) and the Burst and Transient Source Experiment (BATSE) aboard the Compton Gamma Ray Observatory (CGRO) were analysed to quantify source variations with time and pulse phase. A numerical model simulating X-ray emission from pulsars in terms of Compton scattering of photons within a neutron star accretion column has been developed to test the consistency of the analysis results and to further investigate the spectral and pulse profile formation. Mean Proportional Counter Array (PCA) spectra of both pulsars over the range 2-40 keV are adequately fitted with a Comptonization model, with blackbody source spectrum To1-1.3 keV, plasma temperature Te 6-10 keV, and optical depth T P..- 2-6. The source spectrum temperature is consistent with an origin at the neutron star polar cap, with Compton scattering taking place primarily in the hot plasma of the accretion column. Both the fitted optical depth and plasma temperature vary significantly with the source flux. The wide range of source luminosity spanned by archival observations of GX 1+4 offers evidence for two distinct spectral states above and below Lx1.4 x 10 erg s' (2-20 keV, assuming a source distance of 10 kpc). GX 1+4 additionally exhibits dramatic hourly variations in neutral column density nHindicative of density variations in the stellar wind from the giant companion. Pulse profiles from GX 1+4 vary dramatically over timescales as short as 6 h. Low-order Fourier decomposition of pulse profiles in the 20-50 keV band from BATSE monitoring of the source, in addition to the pulse profiles observed by RXTE over a broader energy range have been used to investigate the relationship between source flux and profile asymmetry suggested on the basis of previously published profiles. The asymmetry of the pulse profiles (as measured by the asymmetry parameter a, Greenhill et al., 1998) exhibits large variation which decreases as the flux increases. No significant relationship is suggested by the recent data, although the span in flux is significantly narrower than from historical profiles which cover the 1970s during which the source was consistently very bright. Pulse-phase spectroscopy of RXTE data from GX 1+4 and RX J0812.4-3114 support the interpretation of the sharp dips in the pulse profile as 'eclipses' of the emission region by the accretion column. The dip phase corresponds with the closest approach of the column axis to the line of sight, and the additional optical depth experienced by photons escaping from the column in this direction gives rise to both the decrease in flux and increase in the fitted T measured at this phase. Analysis of the arrival time of individual dips in GX 1+4 provides the first measurement of azimuthal wandering of a neutron star accretion column. The column longitude varies stochastically with standard deviation 2-6° depending on the source luminosity. Measurements of the phase width of the dip both from mean pulse profiles and individual eclipses demonstrates that the dip width is proportional to the flux. The variation is consistent with that expected if the azimuthal extent of the accretion column depends only upon the Keplerian velocity at the inner disc radius, which varies as a consequence of the accretion rate M. A numerical model using a Monte-Carlo approach has been developed to investigate the behaviour of the emission model suggested by the analysis results. The model simulates Comptonization of a source of blackbody photons emitted from the polar cap of a canonical neutron star in a semi-infinite cylindrical accretion column. The mean spectra vary with both inclination angle and magnetic colatitude (the source aspect). For certain ranges of aspect the pulse profiles exhibit dips similar to those observed in GX 1+4 and RX J0812.4-3114, although not as sharp. Pulse phase spectroscopy of the model data confirms the increase in fitted T coincident with the dip. Latitudinal variations in density across the column, suggested as a possible source of profile asymmetry, result in significant asymmetry only if the brightness of the two poles is unequal.

We construct a new formulation that allows efficient exploration of steady-state accretion processes onto compact objects. Accretion onto compact objects is a common scenario in astronomy. These systems serve as laboratories to probe the nuclear burning of the accreted matter. Conventional stellar evolution codes have been developed to simulate in detail the nuclear reactions on the compact objects. In order to follow the case of steady burning, however, using these codes can be very expensive as they are designed to follow a time-dependent problem. Here we introduce our new code $\textsc{StarShot}$, which resolves the structure of the compact objects for the case of stable thermonuclear burning, and is able to follow all nuclear species using an adaptive nuclear reaction network and adaptive zoning. Compared to dynamical codes, the governing equations can be reduced to time-independent forms under the assumption of steady-state accretion. We show an application to accreting low mass X-ray binaries (LMXBs) with accretion onto a neutron-star as compact object. The computational efficiency of $\textsc{StarShot}$ allows to to explore the parameter space for stable burning regimes, and can be used to generate initial conditions for time-dependent evolution models., Comment: 11 pages, 4 figures

The Bering Sea in winter (October-April) is defined by a seasonal ice cover and stormy seas; average significant wave height (SWH) is 2.7 m, double the May-September average. Every winter, 20 days on average exhibit SWHs larger than 9 m. Our analysis of surface wind and wave conditions suggests enhanced storminess. The past 5 years are among the 6 stormiest in the last 20 years, indicated by an increase of 0.5 m/s/decade in the highest 1% of surface wind speeds and an increase of 0.5 m/decade in the highest 1% of SWHs. Observations also show a trend in Bering Sea ice extent of -30.5 %/decade in March between 2012-2022. This is in stark contrast to the previous three decades when ice extent was relatively stable (+1.7 %/decade). If we were to assume a continuing linear decline in ice extent, current conditions suggest the Central Shelf area (St. Matthew Island) would be ice free in winter by the early 2030s. Since the sea ice and storm seasons overlap, we hypothesize that a decline in sea ice would increase the frequency of high waves over the shelf, severely impacting coastal communities. In September 2022, extratropical cyclone Merbok caused unprecedented wave conditions (SWH > 15 m) over the shelf that were uncharacteristic for the season, resulting in widespread coastal inundation and property damage. This demonstrated the emerging threat storms pose in a future where sea ice is largely absent from the Bering Sea shelf region in winter, when severe storms are common., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Pyrazoles are ubiquitous structures in medicinal chemistry. We report the first regioselective route to C3-hydroxyarylated pyrazoles obtained through reaction of pyrazole

Model-based market segmentation analyses often involve an ordinal dependent variable as ordinal responses are frequently collected in marketing research. In the Bayesian segmentation literature, there are models for an interval- or ratio-scaled dependent variable but there is not any general model for an ordinal dependent variable. In this manuscript, the authors propose a new Bayesian procedure to simultaneously perform segmentation and ordinal regression with variable selection within each derived segment. The procedure is robust to outliers and it also provides an option to include concomitant variables that allows the simultaneous profiling of the derived segments. The authors demonstrate that the practice of treating ordinal responses as interval- or ratio-scales to apply existing Bayesian segmentation procedures can lead to very misleading results and conclusions. Through simulation studies, the authors show that the proposed procedure outperforms several benchmark Bayesian segmentation models in parameter recovery, segment retention, and segment membership prediction for such data. Finally, they provide a commercial business customer satisfaction empirical application to illustrate the usefulness of the proposed model.

Neutron stars in low mass X-ray binaries are hypothesised to emit continuous gravitational waves that may be detectable by ground-based observatories. The torque balance model predicts that a higher accretion rate produces larger-amplitude gravitational waves, hence low mass X-ray binaries with high X-ray flux are promising targets for gravitational wave searches. The detection of X-ray pulsations would identify the spin frequency of these neutron stars, and thereby improve the sensitivity of continuous gravitational-wave searches by reducing the volume of the search parameter space. We perform a semi-coherent search for pulsations in the two low mass X-ray binaries Scorpius X-1 and Cygnus X-2 using X-ray data from the \textit{ Rossi X-ray Timing Explorer} Proportional Counter Array. We find no clear evidence for pulsations, and obtain upper limits (at $90\%$ confidence) on the fractional pulse amplitude, with the most stringent being $0.034\%$ for Scorpius X-1 and $0.23\%$ for Cygnus X-2. These upper limits improve upon those of Vaughan et al. (1994) by factors of $\sim 8.2$ and $\sim 1.6$ respectively., 10 pages, 11 figures

The optimized exploitation of perovskite nanocrystals and nanoplatelets as highly efficient light sources requires a detailed understanding of the energy spacing within the exciton manifold. Dark exciton states are particularly relevant because they represent a channel that reduces radiative efficiency. Here, we apply large in-plane magnetic fields to brighten optically inactive states of CsPbBr

Large-scale sky surveys have played a transformative role in our understanding of astrophysical transients, only made possible by increasingly powerful machine learning-based filtering to accurately sift through the vast quantities of incoming data generated. In this paper, we present a new real-bogus classifier based on a Bayesian convolutional neural network that provides nuanced, uncertainty-aware classification of transient candidates in difference imaging, and demonstrate its application to the datastream from the GOTO wide-field optical survey. Not only are candidates assigned a well-calibrated probability of being real, but also an associated confidence that can be used to prioritise human vetting efforts and inform future model optimisation via active learning. To fully realise the potential of this architecture, we present a fully-automated training set generation method which requires no human labelling, incorporating a novel data-driven augmentation method to significantly improve the recovery of faint and nuclear transient sources. We achieve competitive classification accuracy (FPR and FNR both below 1%) compared against classifiers trained with fully human-labelled datasets, whilst being significantly quicker and less labour-intensive to build. This data-driven approach is uniquely scalable to the upcoming challenges and data needs of next-generation transient surveys. We make our data generation and model training codes available to the community., 17 pages, 12 figures, resubmitted to MNRAS following reviewer comments

Current methods for the preparation of heterobifunctional pomalidomide-conjugates rely on methods that are often low yielding and produce intractable byproducts. Herein we describe our strategy for the reliable and succinct preparation of pomalidomide-linkers which is essential to the formation of these conjugates. We present the preparation of 18 pomalidomide-linkers in high yield compared to current literature methods. Our findings show that secondary amines consistently afford greater yields than their primary counterparts, a trend that we were able to exploit in the synthesis of several new pomalidomide homo-dimers in enhanced yields compared to similar literature syntheses. This trend was further utilised to develop the first one-pot synthesis of JQ1-pomalidomide conjugates in yields up to 62%, providing a method that is suited to rapid preparation of conjugate libraries as is frequently required for the development of new protein degraders., Current methods for the preparation of heterobifunctional pomalidomide-conjugates rely on methods that are often low yielding and produce intractable byproducts. Herein we describe our strategy for the succinct preparation of pomalidomide-linkers.

In this data release from the ongoing LOw-Frequency ARray (LOFAR) Two-metre Sky Survey we present 120–168 MHz images covering 27% of the northern sky. Our coverage is split into two regions centred at approximately 12h45m +44◦300 and 1h00m +28◦000 and spanning 4178 and 1457 square degrees respectively. The images were derived from 3451 h (7.6 PB) of LOFAR High Band Antenna data which were corrected for the direction-independent instrumental properties as well as direction-dependent ionospheric distortions during extensive, but fully automated, data processing. A catalogue of 4 396 228 radio sources is derived from our total intensity (Stokes I) maps, where the majority of these have never been detected at radio wavelengths before. At 600 resolution, our full bandwidth Stokes I continuum maps with a central frequency of 144 MHz have: a median rms sensitivity of 83 µJy beam−1 ; a flux density scale accuracy of approximately 10%; an astrometric accuracy of 0.200; and we estimate the point-source completeness to be 90% at a peak brightness of 0.8 mJy beam−1 . By creating three 16 MHz bandwidth images across the band we are able to measure the in-band spectral index of many sources, albeit with an error on the derived spectral index of >±0.2 which is a consequence of our flux-density scale accuracy and small fractional bandwidth. Our circular polarisation (Stokes V) 2000 resolution 120–168 MHz continuum images have a median rms sensitivity of 95 µJy beam−1 , and we estimate a Stokes I to Stokes V leakage of 0.056%. Our linear polarisation (Stokes Q and Stokes U) image cubes consist of 480 × 97.6 kHz wide planes and have a median rms sensitivity per plane of 10.8 mJy beam−1 at 40 and 2.2 mJy beam−1 at 2000; we estimate the Stokes I to Stokes Q/U leakage to be approximately 0.2%. Here we characterise and publicly release our Stokes I, Q, U and V images in addition to the calibrated uv-data to facilitate the thorough scientific exploitation of this unique dataset.

Millihertz quasi-periodic oscillations (mHz QPOs) observed in neutron-star low-mass X-ray binaries (NS LMXBs) are generally explained as marginally stable thermonuclear burning on the neutron star surface. We report the discovery of mHz QPOs in an XMM-Newton observation of the transient 1RXS J180408.9$-$342058, during a regular bursting phase of its 2015 outburst. We found significant periodic signals in the March observation, with frequencies in the range $5-8\,\mathrm{mHz}$, superimposed on a strong $\sim1/f$ power-law noise continuum. Neither the QPO signals nor the power-law noise were present during the April observation, which exhibited a $2.5\times$ higher luminosity and had correspondingly more frequent bursts. When present, the QPO signal power decreases during bursts and disappears afterwards, similar to the behaviour in other sources. 1RXS J180408.9$-$342058 is the eighth source known to date that exhibits such QPOs driven by thermonuclear burning. We examine the range of properties of the QPO signals in different sources. Whereas the observed oscillation profile is similar to that predicted by numerical models, the amplitudes are significantly higher, challenging their explanation as originating from marginally stable burning., 6 pages, 6 figures, 1 table, accepted by MNRAS

We measured the thermonuclear burning efficiency as a function of accretion rate for the Type I X-ray bursts of five low-mass X-ray binary systems. We chose sources with measured neutron star spins and a substantial population of bursts from a large observational sample. The general trend for the burst rate is qualitatively the same for all sources; the burst rate first increases with the accretion rate up to a maximum, above which the burst rate declines, despite the increasing accretion rate. At higher accretion rates, when the burst rate decreases, the {\alpha}-value (the ratio of accretion energy and burst energy) increases by up to a factor of 10 above that in the rising burst rate regime. These observations are contrary to the predictions of 1D numerical models, but can be explained as the consequence of a zone of stable burning on the neutron star surface, which expands with increasing accretion rate. The stable burning also "pollutes" the unstable burning layer with ashes, contributing to the change in burst properties measured in the falling burst rate regime. We find that the mass accretion rate at which the burst rate begins to decrease is anti-correlated with the spin of the neutron star. We conclude that the neutron star spin is a key factor, moderating the nuclear burning stability, via the local accretion rate and fuel composition over the star., Comment: Submitted to MNRAS

This Working Paper presents three separate comments on Servaas Storm’s “The Economics and Politics of Social Democracy: A Reconsideration”. The first is by Joseph Halevi and Peter Kriesler; the second is by Duncan Foley; and the third is by Thomas Ferguson.

This paper surveys the development of the concept of socialism from the French Revolution to the socialist calculation debate. Karl Marx’s politics of revolutionary socialism led by an empowered proletariat nurtured by capital accumulation envisions socialism as a “top-down” system resting on political institutions, despite Marx’s keen appreciation of the long-period analysis of the organization of social production in the classical political economists. Collectivist thinking in the work of Enrico Barone and Wilfredo Pareto paved the way for the discussion of socialism purely in terms of the allocation of resources. The Soviet experiment abandoned the mixed economy model of the New Economic Policy for a political-bureaucratic administration of production only loosely connected to theoretical concepts of socialism. The socialist calculation debate reductively recast the problem of socialism as a problem of allocation of resources, leading to general equilibrium theory. Friedrich Hayek responded to the socialist calculation debate by shifting the ground of discussion from class relations to information revelation.

Optimal control theory and information technology provide tools with the capacity to implement top-down centralized allocation of resources in complex economies organized through a social division of labor. Twentieth century political and systems thinking, however, emphasize the virtues of bottom-up spontaneously organized systems. Workers’ control can be analyzed as one variety of bottom-up spontaneous organization. Another is peer production, as in the case of open-source software. A model of peer production under the name Lifenet provides some insights into the advantages and limitations of this approach to socialism.

Lanthanide-doped nanoparticles enable conversion of near-infrared photons to visible ones. This property is envisioned as a basis of a broad range of applications: from optoelectronics, via energy conversion, to bio-sensing and phototherapy. The spectrum of applications can be extended if magnetooptical properties of lanthanide dopants are well understood. However, at present, there are many conflicting reports on the influence of the magnetic field on the upconverted luminescence. In this work, we resolve this discrepancy by performing a comprehensive study of β-NaYF4:Er3+,Yb3+ nanoparticles. Crucially, we show that the magnetic field impacts the luminescence only via a Zeeman-driven detuning between the excitation laser and the absorption transition. On the other hand, the energy transfer and multiphonon relaxation rates are unaffected. We propose a phenomenological model, which qualitatively reproduces the experimental results. The presented results are expected to lead to design of novel, dual-mode opto-magnetic upconverting nanomaterials.

We present a sample of 373 peaked-spectrum (PS) sources with spectral peaks around 150MHz, selected using a subset of two LOFAR all-sky surveys, the LOFAR Two Meter Sky Survey and the LOFAR LBA Sky Survey. These surveys are the most sensitive low-frequency widefield surveys to date, allowing us to select low-luminosity PS sources. Our sample increases the number of known PS sources in our survey area by a factor 50. The 5GHz luminosity distribution of our PS sample shows we sample the lowest luminosity PS sources to-date by nearly an order of magnitude. Since high-frequency PS sources and compact steep-spectrum sources are hypothesised to be the precursors to large radio galaxies, we investigate whether this is also the case for our sample of low-frequency PS sources. Using optical line emission criteria, we find that our PS sources are predominately high-excitation radio galaxies instead of low-excitation radio galaxies, corresponding to a quickly evolving population. We compute the radio source counts of our PS sample, and find they are scaled down by a factor of $\sim$40 compared to a general sample of radio-loud active galactic nuclei (AGN). This implies that the lifetimes of PS sources are 40 times shorter than large scale radio galaxies, if their luminosity functions are identical. To investigate this, we compute the first radio luminosity function for a homogeneously-selected PS sample. We find that for 144MHz luminosities $\gtrsim 10^{25}$W Hz$^{-1}$, the PS luminosity function has the same shape as an unresolved radio-loud AGN population but shifted down by a factor of $\sim$10. We interpret this as strong evidence that these high-luminosity PS sources evolve into large-scale radio-loud AGN. For local, low-luminosity PS sources, there is a surplus of PS sources, which we hypothesise to be the addition of frustrated PS sources that do not evolve into large-scale AGN., Comment: 21 pages, accepted in Astronomy & Astrophysics

Links between the properties of radio-loud active galactic nuclei (RLAGNs) and the morphology of their hosts may provide important clues for our understanding of how RLAGNs are triggered. In this work, focusing on passive galaxies, we study the shape of the hosts of RLAGNs selected from the Karl G. Jansky Very Large Array Cosmic Evolution Survey (VLA-COSMOS) 3GHz Large Project, and compare them with previous results based on the first data release (DR1) of the LOFAR Two-Metre Sky Survey (LoTSS). We find that, at redshifts of between 0.6 and 1, high-luminosity ($L_{1.4 GHz}\gtrsim10^{24}\rm W Hz^{-1}$) RLAGNs have a wider range of optical projected axis ratios than their low-redshift counterparts, which are essentially all found in round galaxies with axis ratios of higher than 0.7. We construct control samples and show that although the hosts of high-redshift RLAGNs with the highest luminosities still have a rounder shape compared with the non-RLAGNs, they on average have a smaller axis ratio (more elongated) than the local RLAGNs with similar stellar masses and radio luminosities. This evolution can be interpreted as a byproduct of radio luminosity evolution, namely that galaxies at fixed stellar mass are more radio luminous at high redshifts: artificially increasing the radio luminosities of local galaxies ($z\leq$0.3) by a factor of 2 to 4 can remove the observed evolution of the axis ratio distribution. If this interpretation is correct then the implication is that the link between AGN radio luminosity and host galaxy shape is similar at $z\simeq1$ to in the present-day Universe., Comment: 10 pages, 6 figures. Accepted by A&A

Thermonuclear (type-I) bursts arise from unstable ignition of accumulated fuel on the surface of neutron stars in low-mass X-ray binaries. Measurements of burst properties in principle enable observers to infer the properties of the host neutron star and mass donors, but a number of confounding astrophysical effects contribute to systematic uncertainties. Here we describe some commonly-used approaches for determining system parameters, including composition of the burst fuel, and introduce a new suite of software tools, concord, intended to fully account for astrophysical uncertainties. Comparison of observed burst properties with the predictions of numerical models is a complementary method of constraining host properties, and the tools presented here are intended to make comprehensive model-observation comparisons straightforward. When combined with the extensive samples of burst observations accumulated by X-ray observatories, these software tools will provide a step-change in the amount of information that can be inferred about typical burst sources., Comment: 22 pages, 11 figures, 1 table & 1 machine-readable table as supplementary data; submitted to ApJS. Accompanying software package available at https://github.com/outs1der/concord

High redshift quasars ($z>5$) that also shine brightly at radio wavelengths are unique signposts of supermassive black hole activity in the early universe. However, bright radio sources at $z\ge5$ are extremely rare and therefore we have started a campaign to search for new high-$z$ quasars by combining an optical dropout selection driven by the $g$, $r$, and $z$ bands from the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys with low-frequency radio observations from the LOFAR Two-metre Sky Survey (LoTSS). Currently, LoTSS covers a large fraction of the northern sky (5720 deg$^2$) to such a depth (median noise level of 83 $\mu$Jy beam$^{-1}$) that about 30% of the general quasar population is detected $-$ which is a factor of 5-10 more than previous large sky radio surveys such as NVSS and FIRST, respectively. In this paper, we present the discovery of 20 new quasars (and the independent confirmation of 4) between $4.9\leq z\leq 6.6$. Out of the 24 quasars, 21 satisfy the traditional radio-loudness criterion of $R=f_{5\text{GHz}}/f_{4400A} > 10$, with the full sample spanning $R\sim$6-1000, thereby more than doubling the sample of known radio-loud quasars at $z \ge 5$. Our radio detection requirement strongly decreases the contamination of stellar sources and allows one to select these quasars in a broad redshift range. Despite selecting our quasar candidates using fewer and less conservative colour restrictions, both the optical and near-infrared colours, Ly$\alpha$ emission line properties, and dust reddening, $E(B-V)$, measurements of our quasar sample do not deviate from the known radio-quiet quasar population, suggesting similar optical quasar properties of the radio-loud and radio-quiet quasar population at high-$z$. Our campaign demonstrates the potential for discovering new high-$z$ quasar populations through next generation radio continuum surveys., Comment: 19 pages, 11 figures, Tab A1 corrected, accepted for publication in A&A

This paper explores the application of information theory and game theory to questions arising in Adam Smith's Wealth of Nations and Karl Marx's critical reformulation of Smith's analysis in Capita...

Multidimensional scaling methods are frequently used by researchers and practitioners to project high dimensional data into a low dimensional space. However, it is a challenge to integrate side information which is available along with the dissimilarities to perform such dimension reduction analysis. A novel Bayesian integrative multidimensional scaling procedure, namely Bayesian multidimensional scaling with variable selection, is proposed to incorporate external information on the objects into the analysis through the use of a latent multivariate regression structure. The proposed Bayesian procedure allows the incorporation of covariate information into the dimension reduction analysis through the use of a variable selection strategy. An efficient computational algorithm to implement the procedure is also developed. A series of simulation experiments and a real data analysis are conducted, and the proposed model is shown to outperform several benchmark models based on some measures commonly used in the literature.

Strain is a commonly used tool to tune the optoelectronic properties of semiconductors. It is especially effective for transition metal dichalcogenides (TMDs), which can withstand extreme strain up to 10%. To date, localised strain fields have been applied by transferring TMDs flakes onto a patterned SiO2 substrate. Here, we present a novel approach, where the strain in MoS2 monolayer is induced by an array of homoepitaxially grown GaAs nanomembranes. This represents a first step towards the integration of TMD monolayers with III–V semiconductor nanostructures, which is essential to develop scalable nanophotonic platforms. The strain imposed by the nanomembrane lifts the degeneracy of the exciton states, leading to linearly polarised emission. The principal axis of the linear polarisation of the emission is strictly determined by the orientation of the nanomembranes. This result is fully consistent with the expected broken crystal symmetry resulting from the imposed uniaxial strain.

A demand-driven alternative to the conventional Solow–Swan growth model is analysed. Its medium run is built around Marx–Goodwin cycles of demand and distribution. Long-run income and wealth distributions follow rules of accumulation stated by Pasinetti in combination with a technical progress function for labour productivity growth incorporating a Kaldor effect and induced innovation. An explicit steady state solution is presented along with analysis of dynamics. When wage income of capitalist households is introduced, the Samuelson–Modigliani steady state ‘dual’ to Pasinetti’s cannot be stable. Numerical simulation loosely based on US data suggests that the long-run growth rate is around 2% per year and that the capitalist share of wealth may rise from about 40 to 70% due to positive medium-term feedback of higher wealth inequality into its own growth.

Mathematical modeling has been proven to be a remarkably effective approach for bio-mathematician to study and understand the behavior of various malicious objects in a computer system. Due to the connection that exist between computer virus and disease infection, a SEIAR compartmental model has been proposed to model and analyses cyberspace attack where S stands for Susceptible, E for Exposed, I for Infected, A for Asymptomatic and R for Recovered. The dynamic of the above model is governed by a set of differential equations which are generally solved by finite difference methods such as Euler method, Crank-Nicolson method, Runge-Kutta method. However, solutions obtained by these methods are stored in a discretized form that presents some limitations in terms of space memory occupied when high resolution result are required or an accumulation of approximation error on every step of a finite-difference methods. In that regards, a deep neural learning approach has been implemented to solve the system of ordinary differential equation of the epidemic model. It has been found that neural network with one hidden layer shows good capacity in approximating the solution of the differential equation and it required less storage comparing to the traditional finite difference methods. For the convergence of the neural network model, BFGS has been a good optimization method compering to the Conjugate Gradient as well as the Limited Memory BFGS methods.

Stimulating broadly neutralizing antibodies (bnAbs) directly from germline remains a barrier for HIV vaccines. HIV superinfection elicits bnAbs more frequently than single infection, providing clues of how to elicit such responses. We used longitudinal antibody sequencing and structural studies to characterize bnAb development from a superinfection case. Mature bnAb QA013.2 bound both initial transmitted and superinfecting virus, but its inferred naïve bound only the superinfecting strain and was not neutralizing. QA013.2 requires residues spanning FWRH1-CDRH1 to attain breadth, which is uncommon for V3-specific bnAbs. A 4.15 Å cryo-EM structure of QA013.2 bound to heterologous native-like trimer showed recognition of V3 signatures (N301, N332, and GDIR). Antigenic profiling revealed that viral escape was achieved not only by changes in the structurally-defined epitope, but also by mutations in V1. These results highlight shared and distinct properties of QA013.2 relative to other V3-specific bnAbs in the setting of sequential, diverse antigenic variants.

SUMMARYSelf-renewal is a crucial property of glioblastoma cells and is enabled by the choreographed function of chromatin regulators and transcription factors. Identifying targetable epigenetic mechanisms of self-renewal could represent an important step toward developing new and effective treatments for this universally lethal cancer. Here we uncover a targetable epigenetic axis of self-renewal mediated by the histone variant macroH2A2. Using patient-derived in vitro and in vivo models, we show that macroH2A2 has a direct role in shaping chromatin accessibility at enhancer elements to antagonize transcriptional programs of self-renewal. Pharmaceutical inhibition of the chromatin remodeler Menin increased macroH2A2 levels and repressed self- renewal. Our results reveal a targetable epigenetic mechanism of self-renewal controlled by macroH2A2 and suggest new treatment approaches for glioblastoma patients.SIGNIFICANCEGlioblastoma is an incurable brain cancer. Malignant self-renewing cells have been shown to drive tumor growth, to be refractory to current treatment approaches and to seed relapses, which ultimately prove lethal. Identifying new and targetable mechanisms associated with self-renewal could be a fundamental first step in designing effective therapies that slow or prevent glioblastoma relapses. Using patient-derived models of glioblastoma, we deployed epigenomic approaches and functional assays to define the role of the histone variant macroH2A2 in repressing self-renewal. We identified compounds that increase macroH2A2 levels and repress self-renewal, including a Menin inhibitor. As Menin inhibitors are being tested in clinical trials, these compounds could be used in new therapeutic paradigms to target self-renewing cell populations in glioblastoma.

In atomically thin two-dimensional (2D) crystals, the excitonic properties and band structure scale strongly with the thickness, providing a new playground for the investigation of exciton physics in the ultimate confinement regime. Here, we demonstrate the evolution of the fundamental excitonic properties, such as reduced mass, wave function extension, and exciton binding energy, in the 2D perovskite (PEA)

Biological neural networks operate at several levels of granularity, from the individual neuron to local neural circuits to networks of thousands of cells. The daily oscillation of the brain’s master clock in the suprachiasmatic nucleus (SCN) rests on a yet to be identified network of connectivity among its ~20,000 neurons. The SCN provides an accessible model to explore neural organization at several levels of organization. To relate cellular to local and global network behaviors, we explore network topology by examining SCN slices in three orientations using immunochemistry, light and confocal microscopy, real-time imaging, and mathematical modeling. Importantly, the results reveal small local groupings of neurons that form intermediate structures, here termed “phaseomes” which can be identified through stable local phase differences of varying magnitude among neighboring cells. These local differences in phase are distinct from the global phase relationship – that between individual cells and the mean oscillation of the overall SCN. The magnitude of the phaseomes’ local phase differences are associated with a global phase gradient observed in the SCN’s rostral-caudal extent. Modeling results show that a gradient in connectivity strength can explain the observed gradient of phaseome strength, an extremely parsimonious explanation for the heterogeneous oscillatory structure of the SCN.Significance statementOscillation is a fundamental property of information sensing and encoding in the brain. Using real time imaging and modeling, we explore encoding of time by examining circadian oscillation in single neurons, small groups of neurons, and the entire nucleus, in the brain’s master: the suprachiasmatic nucleus (SCN). New insights into the network organization underlying circadian rhythmicity include the discovery of intermediate structures, termed ‘phaseomes’, characterized by neurons which are stably out of phase with their neighbors. Modeling indicates that the pattern of phaseomes across the tissue encompasses a gradient in connectivity strength from the rostral to caudal aspects of the nucleus. Anisotropy in network organization emerges from comparisons of phaseomes and connectivity gradients in sagittal, horizontal and coronal slices.

Optically luminous quasars at $z > 5$ are important probes of super-massive black hole (SMBH) formation. With new and future radio facilities, the discovery of the brightest low-frequency radio sources in this epoch would be an important new probe of cosmic reionization through 21-cm absorption experiments. In this work, we systematically study the low-frequency radio properties of a sample of 115 known spectroscopically confirmed $z>5$ quasars using the second data release of the Low Frequency Array (LOFAR) Two Metre Sky survey (LoTSS-DR2), reaching noise levels of $\sim$80 $��$Jy beam$^{-1}$ (at 144 MHz) over an area of $\sim5720$ deg$^2$. We find that 41 sources (36%) are detected in LoTSS-DR2 at $>2 ��$ significance and we explore the evolution of their radio properties (power, spectral index, and radio loudness) as a function of redshift and rest-frame ultra-violet properties. We obtain a median spectral index of $-0.29^{+0.10}_{-0.09}$ by stacking 93 quasars using LoTSS-DR2 and Faint Images of the Radio Sky at Twenty Centimetres (FIRST) data at 1.4 GHz, in line with observations of quasars at $z, 11 pages, 10 figures, accepted for publication in A&A

DW Cnc is an intermediate polar which has previously been observed in both high and low states. Observations of the high state of DW Cnc have previously revealed a spin period at ~ 38.6 min, however observations from the 2018/19 low state showed no evidence of the spin period. We present results from our analysis of 12 s cadence photometric data collected by NGTS of DW Cnc during the high state which began in 2019. Following the previously reported suppression of the spin period signal we identify the return of this signal during the high state, consistent with previous observations of it. We identify this as the restarting of accretion during the high state. We further identified three short outbursts lasting ~ 1 d in DW Cnc with a mean recurrence time of ~ 60 d and an amplitude of ~ 1 mag. These are the first outbursts identified in DW Cnc since 2008. Due to the short nature of these events we identify them not as a result of accretion instabilities but instead either from instabilities originating from the interaction of the magnetorotational instability in the accretion disc and the magnetic field generated by the white dwarf or the result of magnetic gating., Comment: Accepted to MNRAS; 8 pages, 4 figues

We present results of our analysis of up to 15 years of photometric data from eight AM CVn systems with orbital periods between 22.5 and 26.8 min. Our data has been collected from the GOTO, ZTF, Pan-STARRS, ASAS-SN and Catalina all-sky surveys and amateur observations collated by the AAVSO. We find evidence that these interacting ultra-compact binaries show a similar diversity of long term optical properties as the hydrogen accreting dwarf novae. We found that AM CVn systems in the previously identified accretion disc instability region are not a homogenous group. Various members of the analysed sample exhibit behaviour reminiscent of Z Cam systems with long super outbursts and standstills, SU UMa systems with regular, shorter super outbursts, and nova-like systems which appear only in a high state. The addition of TESS full frame images of one of these systems, KL Dra, reveals the first evidence for normal outbursts appearing as a precursor to super outbursts in an AM CVn system. Our results will inform theoretical modelling of the outbursts of hydrogen deficient systems., Comment: 11 Pages, 7 Figures, 2 Tables. Accepted for publication in MNRAS. Author's final submitted version

The Gravitational-wave Optical Transient Observer (GOTO) is a wide-field telescope project focused on detecting optical counterparts to gravitational-wave sources. GOTO uses arrays of 40 cm unit telescopes (UTs) on a shared robotic mount, which scales to provide large fields of view in a cost-effective manner. A complete GOTO mount uses 8 unit telescopes to give an overall field of view of 40 square degrees, and can reach a depth of 20th magnitude in three minutes. The GOTO-4 prototype was inaugurated with 4 unit telescopes in 2017 on La Palma, and was upgraded to a full 8-telescope array in 2020. A second 8-UT mount will be installed on La Palma in early 2021, and another GOTO node with two more mount systems is planned for a southern site in Australia. When complete, each mount will be networked to form a robotic, dual-hemisphere observatory, which will survey the entire visible sky every few nights and enable rapid follow-up detections of transient sources., Comment: 8 pages, 5 figures, 1 table, submitted to SPIE Astronomical Telescopes + Instrumentation 2020

The Gravitational-wave Optical Transient Observer (GOTO) is a wide-field telescope project focused on detecting optical counterparts to gravitational-wave sources. The GOTO Telescope Control System (G-TeCS) is a custom robotic control system which autonomously manages the GOTO telescope hardware and nightly operations. Since the commissioning the GOTO prototype on La Palma in 2017, development of the control system has focused on the alert handling and scheduling systems. These allow GOTO to receive and process transient alerts and then schedule and carry out observations, all without the need for human involvement. GOTO is ultimately anticipated to include multiple telescope arrays on independent mounts, both on La Palma and at a southern site in Australia. When complete these mounts will be linked to form a single multi-site observatory, requiring more advanced scheduling systems to best optimise survey and follow-up observations., 12 pages, 6 figures, 2 tables, submitted to SPIE Astronomical Telescopes + Instrumentation 2020

Introduction: COVID-19, a coronavirus disease 2019, is an ongoing pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). There have been a lot of attempts to model this pandemic from a global perspective. The Novel Coronavirus is still spreading quickly in several countries and the peak has not yet been reached in many countries. We developed age-structured model for describing the COVID-19 pandemic in Kenya under different non-pharmaceutical interventions. The first case in Kenya was identified in March 13, 2020 with the pandemic increasing to 465 confirmed cases by end of 3rd May, 2020. We fitted an age-structured deterministic mathematical model in Kenyan context.Methods: We model the COVID-19 situation in Kenya using Age-structured Susceptible Exposed Infectious Recovered compartmental model. These compartments follow a cascade of the disease from the Susceptible to Exposed individuals who in return are either symptomatic or asymptomatic. The symptomatic depict mild signs, which can develop to severe symptoms warranting hospitalization or can otherwise recover. The severe cases can recover with some developing critical condition. The critical are admitted at intensive care units. The resulting age-dependent ordinary differential equations from the model are solved using fourth order Runge-Kutta methods. We controlled for school closure, social distancing and lockdown in terms of movement restrictionsResults: The model shows varying epidemic peak by age-structure and the mitigation scenarios. The peak dates for unmitigated (UM), the 45% NPI (M45) and School closure-curfew-partial lockdown NPI (SCL) are May 21st, October 17th and December 13th 2020, respectively. Their respective cumulative infections peaks are 43M, 24M and 25M. The daily reported severe cases, critical cases and death proportionately increased with age. Conclusions: The cumulative number of infections reduces greatly with introduction of school closure, social distancing and restricted movement in highly affected counties. The degree of COVID-19 severity increases with age. However, it is not immediately clear when these restrictions can be lifted.

Type-I X-ray bursts arise from unstable thermonuclear burning of accreted fuel on the surface of neutron stars. In this chapter we review the fundamental physics of the burning processes, and summarise the observational, numerical, and nuclear experimental progress over the preceding decade. We describe the current understanding of the conditions that lead to burst ignition, and the influence of the burst fuel on the observational characteristics. We provide an overview of the processes which shape the burst X-ray spectrum, including the observationally elusive discrete spectral features. We report on the studies of timing behaviour related to nuclear burning, including burst oscillations and mHz quasi-periodic oscillations. We describe the increasing role of nuclear experimental physics in the interpretation of astrophysical data and models. We survey the simulation projects that have taken place to date, and chart the increasing dialogue between modellers, observers, and nuclear experimentalists. Finally, we identify some open problems with prospects of a resolution within the timescale of the next such review.

Lanthanide-doped nanoparticles enable conversion of near-infrared photons to visible ones. This property is envisioned as a basis of a broad range of applications: from optoelectronics, via energy conversion, to bio-sensing and phototherapy. The spectrum of applications can be extended if magnetooptical properties of lanthanide dopants are well understood. However, at present, there are many conflicting reports on the influence of the magnetic field on the upconverted luminescence. In this work, we resolve this discrepancy by performing a comprehensive study of β-NaYF4:Er3+,Yb3+ nanoparticles. Crucially, we show that the magnetic field impacts the luminescence only via a Zeeman-driven detuning between the excitation laser and the absorption transition. On the other hand, the energy transfer and multiphonon relaxation rates are unaffected. We propose a phenomenological model, which qualitatively reproduces the experimental results. The presented results are expected to lead to design of novel, dual-mode opto-magnetic upconverting nanomaterials.

Social multipliers occur when individual actions influence other individual actions so as to lead to amplified aggregate effects. Epidemic infections offer a dramatic example of this phenomenon since individual actions such as social distancing and masking that have small effects on individuals’ risk can have very large effects in reducing risk when they are widely adopted. This paper uses the info-metric method of constrained maximum entropy modeling to estimate the impact of social multiplier effects in the Covid-19 epidemic with a model that infers the length of infection, the rate of mortality, the base infection factor, and reductions in the infection factor due to changes in social behavior from data on daily infections and deaths. When the model takes account of the rate of reporting of infections, it can produce three rather different scenarios of epidemic dynamics, which have marginally different posterior probabilities: one in which reporting is very low, under 10% and the estimated infection is correspondingly large, and immunity effects play a significant role in stabilizing the epidemic; a second in which reporting is on the order of 25% and the model estimates a significant portion of the population as having inherent immunity to the infection; and a third where reporting rates are close to 100%, and the epidemic is controlled mostly by changes in social behavior. These qualitatively different scenarios reflect the limited data the method can extract information from in this case.

The family of 2D Ruddlesden-Popper perovskites is currently attracting great interest of the scientific community as highly promising materials for energy harvesting and light emission applications. Despite the fact that these materials are known for decades, only recently has it become apparent that their optical properties are driven by the exciton-phonon coupling, which is controlled by the organic spacers. However, the detailed mechanism of this coupling, which gives rise to complex absorption and emission spectra, is the subject of ongoing controversy. In this work we show that the particularly rich, absorption spectra of (PEA)

A growth model incorporating dynamics of capital per capita, atmospheric CO2 concentration, and labor and energy productivity is described. In the “medium run,†output and employment are determined by effective demand in contrast to most models of climate change. In a “long run†of several centuries the model converges to a stationary state with zero net emissions of CO2. Properties of dismal and non-dismal stationary states are explored, with a latter requiring a relatively high level of investment in mitigation of emissions. Without such investment under “business as usual,†output dynamics are strongly cyclical in numerical simulations. There is strong output growth for about eight decades, then a climate crisis, and output crash.

The problem of expectations in economic models is reviewed through the intellectual development of the author. Initial efforts at macroeconomic modeling such as Foley–Sidrauski (Foley and Sidrauski 1971) treated expectations as conditioning variables for representative agent stock demands and supplies of financial and real assets. Perfect foresight (rational expectations) in this context leads to saddle-point instability of equilibrium, and the unanswered question of what behavioral forces will guarantee that the economy stays on the stable manifold. In later work such as Foley–Albin (Albin 1998), the economy appears as a complex, adaptive system far from equilibrium in which endogenous regime shifts make the statistical formation of expectations impossible. This perspective calls into question the presumed central role of expectations formation in structuring macroeconomic dynamics. The quantal response statistical equilibrium model can throw some light on the process by which markets penalize incorrect expectations of price change.