The Rules of Human T Cell Fate in vivo.

The processes governing lymphocyte fate (division, differentiation, and death), are typically assumed to be independent of cell age. This assumption has been challenged by a series of elegant studies which clearly show that, for murine cells in vitro, lymphocyte fate is age-dependent and that younger cells (i.e., cells which have recently divided) are less likely to divide or die. Here we investigate whether the same rules determine human T cell fate in vivo. We combined data from in vivo stable isotope labeling in healthy humans with stochastic, agent-based mathematical modeling. We show firstly that the choice of model paradigm has a large impact on parameter estimates obtained using stable isotope labeling i.e., different models fitted to the same data can yield very different estimates of T cell lifespan. Secondly, we found no evidence in humans in vivo to support the model in which younger T cells are less likely to divide or die. This age-dependent model never provided the best description of isotope labeling; this was true for naïve and memory, CD4+ and CD8+ T cells. Furthermore, this age-dependent model also failed to predict an independent data set in which the link between division and death was explored using Annexin V and deuterated glucose. In contrast, the age-independent model provided the best description of both naïve and memory T cell dynamics and was also able to predict the independent dataset

Time-dependent analysis of B^0 → K^0_Sπ^−π^^+γ decays and studies of the K^+π^−π^+ system in B^+ → K^+π^−π^+γ decays

We measure the time-dependent CP asymmetry in the radiative-penguin decay B^0→K^0_Sπ^−π^+γ, using a sample of 471×10^6 Υ(4S)→BB¯ events recorded with the BABAR detector at the PEP-II e^+e^− storage ring at SLAC. Using events with mKππ<1.8  GeV/c^2, we measure the branching fractions of B^+→K^+π^−π^+γ and B^0→K^0π^−π^+γ, the branching fractions of the kaonic resonances decaying to K^+π^−π^+, as well as the overall branching fractions of the B^+→ρ^0K^+γ, B^+→K^(*0)π^+γ and S-wave B^+→(Kπ)^(*0)_0π^+γ components. For events from the ρ mass band, we measure the CP-violating parameters SK^0_Sπ^+π^−γ=0.14±0.25±0.03 and CK^0_Sπ^+π^−γ=−0.39±0.20+0.03−0.02, where the first uncertainties are statistical and the second are systematic. We extract from this measurement the time-dependent CP asymmetry related to the CP eigenstate ρ^0K^0_S and obtain SK^0_(Sργ)=−0.18±0.32^(+0.06)_(−0.05), which provides information on the photon polarization in the underlying b→sγ transition

Quantum-fluid dynamics of microcavity polaritons

Semiconductor microcavities offer a unique system to investigate the physics of weakly interacting bosons. Their elementary excitations, polaritons--a mixture of excitons and photons--behave, in the low density limit, as bosons that can undergo a phase transition to a regime characterised by long range coherence. Condensates of polaritons have been advocated as candidates for superfluidity; and the formation of vortices as well as elementary excitations with a linear dispersion are actively sought after. In this work, we have created and set in motion a macroscopically degenerate state of polaritons and let it collide with a variety of defects present in the sample. Our experiments show striking manifestations of a coherent light-matter packet that displays features of a superfluid, although one of a highly unusual character as it involves an out-of-equilibrium dissipative system where it travels at ultra-fast velocity of the order of 1% the speed of light. Our main results are the observation of i) a linear polariton dispersion accompanied with diffusion-less motion, ii) flow without resistance when crossing an obstacle, iii) suppression of Rayleigh scattering and iv) splitting into two fluids when the size of the obstacle is comparable with the size of the wavepacket. This work opens the way to the investigation of new phenomenology of out-of-equilibrium condensates.Comment: 22 pages, 5 figure

Beyond viral suppression of HIV – the new quality of life frontier

BACKGROUND: In 2016, the World Health Organization (WHO) adopted a new Global Health Sector Strategy on HIV for 2016–2021. It establishes 15 ambitious targets, including the ‘90-90-90’ target calling on health systems to reduce under-diagnosis of HIV, treat a greater number of those diagnosed, and ensure that those being treated achieve viral suppression. DISCUSSION: The WHO strategy calls for person-centered chronic care for people living with HIV (PLHIV), implicitly acknowledging that viral suppression is not the ultimate goal of treatment. However, it stops short of providing an explicit target for health-related quality of life. It thus fails to take into account the needs of PLHIV who have achieved viral suppression but still must contend with other intense challenges such as serious non-communicable diseases, depression, anxiety, financial stress, and experiences of or apprehension about HIV-related discrimination. We propose adding a ‘fourth 90’ to the testing and treatment target: ensure that 90 % of people with viral load suppression have good health-related quality of life. The new target would expand the continuum-of-services paradigm beyond the existing endpoint of viral suppression. Good health-related quality of life for PLHIV entails attention to two domains: comorbidities and self-perceived quality of life. CONCLUSIONS: Health systems everywhere need to become more integrated and more people-centered to successfully meet the needs of virally suppressed PLHIV. By doing so, these systems can better meet the needs of all of their constituents – regardless of HIV status – in an era when many populations worldwide are living much longer with multiple comorbidities

Migrant Health: Sexual transmission of HIV within migrant groups in the EU/EEA and implications for effective interventions

This report presents the published evidence of sexual transmission of HIV among populations from countries with generalised HIV epidemics in the European Union/European Economic Area (EU/EEA). Member states’ surveillance systems for monitoring the sexual transmission of HIV in the EU/EEA among migrant populations are also profiled. The implications of this evidence are summarised and recommendations provided for those Member States that wish to improve their surveillance systems in order to assess the sexual transmission of HIV in their at-risk migrant populations. The evidence can also be used as a basis for policy and programmatic activities targeted toward migrant populations

Overview of the CKM Matrix

The current status of the determination of the elements of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix is reviewed. Tensions in the global fits are highlighted. Particular attention is paid to progress in, and prospects for, measurements of CP violation effects.Comment: Proceedings of the Lepton Photon 2011 Conference, to appear in "Pramana - journal of physics", 17 pages, 13 figure

Analysis of the radiative decays among the charmonium states

In this article, we study the radiative decays among the charmonium states with the heavy quark effective theory, and make predictions for the ratios among the radiative decay widths of an special multiplet to another multiplet. The predictions can be confronted with the experimental data in the future and put additional constraints in identifying the $X$, $Y$, $Z$ charmonium-like mesons.Comment: 12 pages, revised revisio

Two-loop Corrections to the B to pi Form Factor from QCD Sum Rules on the Light-Cone and |V(ub)|

We calculate the leading-twist O(alphas^2 beta0) corrections to the B to pi transition form factor f+(0) in light-cone sum rules. We find that, as expected, there is a cancellation between the O(alphas^2 beta0) corrections to fB f+(0) and the large corresponding corrections to fB, calculated in QCD sum rules. This suggests the insensitivity of the form factors calculated in the light-cone sum rules approach to this source of radiative corrections. We further obtain an improved determination of the CKM matrix element |V(ub)|, using latest results from BaBar and Belle for f+(0)|V(ub)|.Comment: 18 pages, 3 figure

Small-molecule conversion of toxic oligomers to nontoxic β-sheet-rich amyloid fibrils

Several lines of evidence indicate that prefibrillar assemblies of amyloid-{beta} (A{beta}) polypeptides, such as soluble oligomers or protofibrils, rather than mature, end-stage amyloid fibrils cause neuronal dysfunction and memory impairment in Alzheimer's disease. These findings suggest that reducing the prevalence of transient intermediates by small molecule-mediated stimulation of amyloid polymerization might decrease toxicity. Here we demonstrate the acceleration of A{beta} fibrillogenesis through the action of the orcein-related small molecule O4, which directly binds to hydrophobic amino acid residues in A{beta} peptides and stabilizes the self-assembly of seeding-competent, {beta}-sheet-rich protofibrils and fibrils. Notably, the O4-mediated acceleration of amyloid fibril formation efficiently decreases the concentration of small, toxic A{beta} oligomers in complex, heterogeneous aggregation reactions. In addition, O4 treatment suppresses inhibition of long-term potentiation by A{beta} oligomers in hippocampal brain slices. These results support the hypothesis that small, diffusible prefibrillar amyloid species rather than mature fibrillar aggregates are toxic for mammalian cells