Aqueous ferrofluids of maghemite nanoparticles coated with carboxydextran were investigated with respect to their specific loss power (SLP) in dependence on frequency and field amplitude of magnetic ...AC-fields. In order to elucidate the effect of the size distribution on SLP fluid fractions with different mean particle core size were prepared by a magnetic separation procedure from the original ferrofluid. Structural characterisation by means of TEM and XRD as well as reconstruction of core size distributions from magnetisation curves reveals that the narrow size distributions of the fractions cover a range of mean core sizes from about 8 up to 20nm. Spectra of the complex susceptibility were measured for a frequency range of 20Hz to 1 MHz. From the imaginary part of the susceptibility the specific loss power is calculated in dependence on frequency. The results are compared with calorimetrical measurements performed in dependence on field amplitude up to 11kA/m at 410kHz. A very high specific loss power in the order of 400W per gram maghemite was found at 410kHz and 11kA/m for the fluid fraction having the largest mean core diameter. A deviation from linear response behaviour is found for this sample showing a power law field dependence of the specific loss power SLP∼H2.5. In addition to liquid suspensions measurements were performed with particles immobilised in mannitol or gel in order to elucidate the role of Brownian relaxation. The experimentally found dependence of SLP on the mean particle core diameter may be understood in the frame of the Debye dispersion model. Results are discussed with respect to applications of ferrofluids in RF-magnetic hyperthermia.
We present detailed forecasts for the constraints on primordial magnetic fields (PMFs) that will be obtained with the LiteBIRD satellite. The constraints are driven by the effects of PMFs on the CMB ...anisotropies: the gravitational effects of magnetically-induced perturbations; the effects on the thermal and ionization history of the Universe; the Faraday rotation imprint on the CMB polarization; and the non-Gaussianities induced in polarization anisotropies. LiteBIRD represents a sensitive probe for PMFs and by exploiting all the physical effects, it will be able to improve the current limit coming from Planck. In particular, thanks to its accurate \(B\)-mode polarization measurement, LiteBIRD will improve the constraints on infrared configurations for the gravitational effect, giving \(B_{\rm 1\,Mpc}^{n_{\rm B} =-2.9} < 0.8\) nG at 95% C.L., potentially opening the possibility to detect nanogauss fields with high significance. We also observe a significant improvement in the limits when marginalized over the spectral index, \(B_{1\,{\rm Mpc}}^{\rm marg}< 2.2\) nG at 95% C.L. From the thermal history effect, which relies mainly on \(E\)-mode polarization data, we obtain a significant improvement for all PMF configurations, with the marginalized case, \(\sqrt{\langle B^2\rangle}^{\rm marg}<0.50\) nG at 95% C.L. Faraday rotation constraints will take advantage of the wide frequency coverage of LiteBIRD and the high sensitivity in \(B\) modes, improving the limits by orders of magnitude with respect to current results, \(B_{1\,{\rm Mpc}}^{n_{\rm B} =-2.9} < 3.2\) nG at 95% C.L. Finally, non-Gaussianities of the \(B\)-mode polarization can probe PMFs at the level of 1 nG, again significantly improving the current bounds from Planck. Altogether our forecasts represent a broad collection of complementary probes, providing conservative limits on PMF characteristics that will be achieved with LiteBIRD.
We study the possibility of using the \(LiteBIRD\) satellite \(B\)-mode survey to constrain models of inflation producing specific features in CMB angular power spectra. We explore a particular model ...example, i.e. spectator axion-SU(2) gauge field inflation. This model can source parity-violating gravitational waves from the amplification of gauge field fluctuations driven by a pseudoscalar "axionlike" field, rolling for a few e-folds during inflation. The sourced gravitational waves can exceed the vacuum contribution at reionization bump scales by about an order of magnitude and can be comparable to the vacuum contribution at recombination bump scales. We argue that a satellite mission with full sky coverage and access to the reionization bump scales is necessary to understand the origin of the primordial gravitational wave signal and distinguish among two production mechanisms: quantum vacuum fluctuations of spacetime and matter sources during inflation. We present the expected constraints on model parameters from \(LiteBIRD\) satellite simulations, which complement and expand previous studies in the literature. We find that \(LiteBIRD\) will be able to exclude with high significance standard single-field slow-roll models, such as the Starobinsky model, if the true model is the axion-SU(2) model with a feature at CMB scales. We further investigate the possibility of using the parity-violating signature of the model, such as the \(TB\) and \(EB\) angular power spectra, to disentangle it from the standard single-field slow-roll scenario. We find that most of the discriminating power of \(LiteBIRD\) will reside in \(BB\) angular power spectra rather than in \(TB\) and \(EB\) correlations.
We present a study of the impact of an uncertainty in the beam far side-lobe knowledge on the measurement of the Cosmic Microwave Background \(B\)-mode signal at large scale. It is expected to be one ...of the main source of systematic effects in future CMB observations. Because it is crucial for all-sky survey missions to take into account the interplays between beam systematic effects and all the data analysis steps, the primary goal of this paper is to provide the methodology to carry out the end-to-end study of their effect for a space-borne CMB polarization experiment, up to the cosmological results in the form of a bias \(\delta r\) on the tensor-to-scalar ratio \(r\). LiteBIRD is dedicated to target the measurement of CMB primordial \(B\) modes by reaching a sensitivity of \(\sigma \left( r \right) \leq 10^{-3}\) assuming \(r=0\). As a demonstration of our framework, we derive the relationship between the knowledge of the beam far side-lobes and the tentatively allocated error budget under given assumptions on design, simulation and component separation method. We assume no mitigation of the far side-lobes effect at any stage of the analysis pipeline. We show that \(\delta r\) is mostly due to the integrated fractional power difference between the estimated beams and the true beams in the far side-lobes region, with little dependence on the actual shape of the beams, for low enough \(\delta r\). Under our set of assumptions, in particular considering the specific foreground cleaning method we used, we find that the integrated fractional power in the far side-lobes should be known at a level as tight as \(\sim 10^{-4}\), to achieve the required limit on the bias \(\delta r < 1.9 \times 10^{-5}\). The framework and tools developed for this study can be easily adapted to provide requirements under different design, data analysis frameworks and for other future space-borne experiments beyond LiteBIRD.
We explore the capability of measuring lensing signals in \(LiteBIRD\) full-sky polarization maps. With a \(30\) arcmin beam width and an impressively low polarization noise of \(2.16\,\mu\)K-arcmin, ...\(LiteBIRD\) will be able to measure the full-sky polarization of the cosmic microwave background (CMB) very precisely. This unique sensitivity also enables the reconstruction of a nearly full-sky lensing map using only polarization data, even considering its limited capability to capture small-scale CMB anisotropies. In this paper, we investigate the ability to construct a full-sky lensing measurement in the presence of Galactic foregrounds, finding that several possible biases from Galactic foregrounds should be negligible after component separation by harmonic-space internal linear combination. We find that the signal-to-noise ratio of the lensing is approximately \(40\) using only polarization data measured over \(90\%\) of the sky. This achievement is comparable to \(Planck\)'s recent lensing measurement with both temperature and polarization and represents a four-fold improvement over \(Planck\)'s polarization-only lensing measurement. The \(LiteBIRD\) lensing map will complement the \(Planck\) lensing map and provide several opportunities for cross-correlation science, especially in the northern hemisphere.
We estimate the efficiency of mitigating the lensing \(B\)-mode polarization, the so-called delensing, for the \(LiteBIRD\) experiment with multiple external data sets of lensing-mass tracers. The ...current best bound on the tensor-to-scalar ratio, \(r\), is limited by lensing rather than Galactic foregrounds. Delensing will be a critical step to improve sensitivity to \(r\) as measurements of \(r\) become more and more limited by lensing. In this paper, we extend the analysis of the recent \(LiteBIRD\) forecast paper to include multiple mass tracers, i.e., the CMB lensing maps from \(LiteBIRD\) and CMB-S4-like experiment, cosmic infrared background, and galaxy number density from \(Euclid\)- and LSST-like survey. We find that multi-tracer delensing will further improve the constraint on \(r\) by about \(20\%\). In \(LiteBIRD\), the residual Galactic foregrounds also significantly contribute to uncertainties of the \(B\)-modes, and delensing becomes more important if the residual foregrounds are further reduced by an improved component separation method.
LiteBIRD is a planned JAXA-led CMB B-mode satellite experiment aiming for launch in the late 2020s, with a primary goal of detecting the imprint of primordial inflationary gravitational waves. Its ...current baseline focal-plane configuration includes 15 frequency bands between 40 and 402 GHz, fulfilling the mission requirements to detect the amplitude of gravitational waves with the total uncertainty on the tensor-to-scalar ratio, \(\delta r\), down to \(\delta r<0.001\). A key aspect of this performance is accurate astrophysical component separation, and the ability to remove polarized thermal dust emission is particularly important. In this paper we note that the CMB frequency spectrum falls off nearly exponentially above 300 GHz relative to the thermal dust SED, and a relatively minor high frequency extension can therefore result in even lower uncertainties and better model reconstructions. Specifically, we compare the baseline design with five extended configurations, while varying the underlying dust modeling, in each of which the HFT (High-Frequency Telescope) frequency range is shifted logarithmically towards higher frequencies, with an upper cutoff ranging between 400 and 600 GHz. In each case, we measure the tensor-to-scalar ratio \(r\) uncertainty and bias using both parametric and minimum-variance component-separation algorithms. When the thermal dust sky model includes a spatially varying spectral index and temperature, we find that the statistical uncertainty on \(r\) after foreground cleaning may be reduced by as much as 30--50 % by extending the upper limit of the frequency range from 400 to 600 GHz, with most of the improvement already gained at 500 GHz. We also note that a broader frequency range leads to better ability to discriminate between models through higher \(\chi^2\) sensitivity. (abridged)
Earth's carbon cycle is strongly influenced by subduction of sedimentary material into the mantle. The composition of the sedimentary subduction flux has changed considerably over Earth's history, ...but the impact of these changes on the mantle carbon cycle is unclear. Here, we show that the carbon isotopes of kimberlite magmas record a fundamental change in their deep-mantle source compositions during the Phanerozoic Eon. The
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C of kimberlites before ~250 Ma preserves typical mantle values, whereas younger kimberlites exhibit lower and more variable ratios-a switch coincident with a recognized surge in kimberlite magmatism. We attribute these changes to increased deep subduction of organic carbon with low
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C following the Cambrian Explosion when organic carbon deposition in marine sediments increased significantly. These observations demonstrate that biogeochemical processes at Earth's surface have a profound influence on the deep mantle, revealing an integral link between the deep and shallow carbon cycles.
LiteBIRD, the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission for primordial cosmology and fundamental ...physics. The Japan Aerospace Exploration Agency (JAXA) selected LiteBIRD in May 2019 as a strategic large-class (L-class) mission, with an expected launch in the late 2020s using JAXA's H3 rocket. LiteBIRD is planned to orbit the Sun-Earth Lagrangian point L2, where it will map the cosmic microwave background (CMB) polarization over the entire sky for three years, with three telescopes in 15 frequency bands between 34 and 448 GHz, to achieve an unprecedented total sensitivity of 2.2\(\mu\)K-arcmin, with a typical angular resolution of 0.5\(^\circ\) at 100 GHz. The primary scientific objective of LiteBIRD is to search for the signal from cosmic inflation, either making a discovery or ruling out well-motivated inflationary models. The measurements of LiteBIRD will also provide us with insight into the quantum nature of gravity and other new physics beyond the standard models of particle physics and cosmology. We provide an overview of the LiteBIRD project, including scientific objectives, mission and system requirements, operation concept, spacecraft and payload module design, expected scientific outcomes, potential design extensions and synergies with other projects.
Chromothripsis is a form of genomic instability characterized by the occurrence of tens to hundreds of clustered DNA double‐strand breaks in a one‐off catastrophic event. Rearrangements associated ...with chromothripsis are detectable in numerous tumor entities and linked with poor prognosis in some of these, such as Sonic Hedgehog medulloblastoma, neuroblastoma and osteosarcoma. Hence, there is a need for therapeutic strategies eliminating tumor cells with chromothripsis. Defects in DNA double‐strand break repair, and in particular homologous recombination repair, have been linked with chromothripsis. Targeting DNA repair deficiencies by synthetic lethality approaches, we performed a synergy screen using drug libraries (n = 375 compounds, 15 models) combined with either a PARP inhibitor or cisplatin. This revealed a synergistic interaction between the HDAC inhibitor romidepsin and PARP inhibition. Functional assays, transcriptome analyses and in vivo validation in patient‐derived xenograft mouse models confirmed the efficacy of the combinatorial treatment.
What's new?
Chromothripsis is a type of genomic instability in which hundreds of chromosomal rearrangements occur at once. In certain tumor types, including medulloblastoma, neuroblastoma and osteosarcoma, chromothripsis is associated with poor prognosis. Here, the authors screened for drug pairs that target and kill tumor cells with chromothripsis while sparing cells that have functional DNA repair. Their screen uncovered a strong synergistic interaction between the HDAC inhibitor romidepsin and PARP inhibitors. Combination therapy worked well to stop tumor growth and induce apoptosis in patient‐derived xenografts.
