161 research outputs found

### Mass concentration in a nonlocal model of clonal selection

Self-renewal is a constitutive property of stem cells. Testing the cancer stem cell hypothesis requires investigation of the impact of self-renewal on cancer expansion. To understand better this impact, we propose a mathematical model describing dynamics of a continuum of cell clones structured by the self-renewal potential. The model is an extension of the finite multi-compartment models of interactions between normal and cancer cells in acute leukemias. It takes a form of a system of integro-differential equations with a nonlinear and nonlocal coupling, which describes regulatory feedback loops in cell proliferation and differentiation process. We show that such coupling leads to mass concentration in points corresponding to maximum of the self-renewal potential and the model solutions tend asymptotically to a linear combination of Dirac measures. Furthermore, using a Lyapunov function constructed for a finite dimensional counterpart of the model, we prove that the total mass of the solution converges to a globally stable equilibrium. Additionally, we show stability of the model in space of positive Radon measures equipped with flat metric. The analytical results are illustrated by numerical simulations

### Asymptotic behaviour of integro-differential equations describing clonal evolution of leukemia

This thesis is devoted to the analysis of a system of integro-differential equations describing leukemia, a type of blood cancer. Existence and uniqueness for arbitrary times are shown and the long-term behaviour of the solution is characterised. In order to achieve the asymptotic behaviour of the solution it is proved that a normalized (with respect to total mass) solution forms a Dirac sequence, thus the solution converges for time tending to infinity to a Dirac measure. Moreover the total mass converges, too, which is shown by combining an asymptotic stability result via a Lyapunov function with a perturbation argument. Additionally, the convergence result is generalised to a suitable measure space. Furthermore, the model is extended by an additional integral term with a small multiplicative coefficient in order to capture the idea of mutation. For this newly obtained system it is shown existence and uniqueness of both a solution for arbitrary times and a positive steady state. The latter is achieved by interpreting the steady state equations as an eigenvalue problem and by using the Krein-Rutman theorem. The local asymptotic stability of the steady state is proven by using linearised stability. The spectrum, which is crucial for linearised stability, is investigated with the method of the Weinstein-Aronszajn formula. Moreover, it is proven that the stable steady state of the extended model converges weakly^* to the stable steady state of the original model if the coefficient of the newly introduced integral term tends to zero. Lastly, a numerical scheme, which has been used to simulate the original model, is illustrated and its convergence to the analytical solution is proven

### New professional roles and patient satisfaction : evidence from a European survey along three clinical pathways

Project is funded by the European Commission, Grant Agreement no: 305467.Peer reviewedPostprin

### Differential limit on the extremely-high-energy cosmic neutrino flux in the presence of astrophysical background from nine years of IceCube data

We report a quasi-differential upper limit on the extremely-high-energy (EHE) neutrino flux above $5\times 10^{6}$ GeV based on an analysis of nine years of IceCube data. The astrophysical neutrino flux measured by IceCube extends to PeV energies, and it is a background flux when searching for an independent signal flux at higher energies, such as the cosmogenic neutrino signal. We have developed a new method to place robust limits on the EHE neutrino flux in the presence of an astrophysical background, whose spectrum has yet to be understood with high precision at PeV energies. A distinct event with a deposited energy above $10^{6}$ GeV was found in the new two-year sample, in addition to the one event previously found in the seven-year EHE neutrino search. These two events represent a neutrino flux that is incompatible with predictions for a cosmogenic neutrino flux and are considered to be an astrophysical background in the current study. The obtained limit is the most stringent to date in the energy range between $5 \times 10^{6}$ and $5 \times 10^{10}$ GeV. This result constrains neutrino models predicting a three-flavor neutrino flux of $E_\nu^2\phi_{\nu_e+\nu_\mu+\nu_\tau}\simeq2\times 10^{-8}\ {\rm GeV}/{\rm cm}^2\ \sec\ {\rm sr}$at$10^9\ {\rm GeV}$. A significant part of the parameter-space for EHE neutrino production scenarios assuming a proton-dominated composition of ultra-high-energy cosmic rays is excluded.Comment: The version accepted for publication in Physical Review

### A united statement of the global chiropractic research community against the pseudoscientific claim that chiropractic care boosts immunity.

BACKGROUND: In the midst of the coronavirus pandemic, the International Chiropractors Association (ICA) posted reports claiming that chiropractic care can impact the immune system. These claims clash with recommendations from the World Health Organization and World Federation of Chiropractic. We discuss the scientific validity of the claims made in these ICA reports. MAIN BODY: We reviewed the two reports posted by the ICA on their website on March 20 and March 28, 2020. We explored the method used to develop the claim that chiropractic adjustments impact the immune system and discuss the scientific merit of that claim. We provide a response to the ICA reports and explain why this claim lacks scientific credibility and is dangerous to the public. More than 150 researchers from 11 countries reviewed and endorsed our response. CONCLUSION: In their reports, the ICA provided no valid clinical scientific evidence that chiropractic care can impact the immune system. We call on regulatory authorities and professional leaders to take robust political and regulatory action against those claiming that chiropractic adjustments have a clinical impact on the immune system
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