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Macrophages are innate immune cells that contribute to fighting infections, tissue repair, and maintaining tissue homeostasis. To enable such functional diversity, macrophages resolve potentially conflicting cues in the microenvironment via mechanisms that are unclear. Here, we use single-cell RNA sequencing to explore how individual macrophages respond when co-stimulated with inflammatory stimuli LPS and IFN-γ and the resolving cytokine IL-4. These co-stimulated macrophages display a distinct global transcriptional program. However, variable negative cross-regulation between some LPS + IFN-γ-specific and IL-4-specific genes results in cell-to-cell heterogeneity in transcription. Interestingly, negative cross-regulation leads to mutually exclusive expression of the T-cell-polarizing cytokine genes Il6 and Il12b versus the IL-4-associated factors Arg1 and Chil3 in single co-stimulated macrophages, and single-cell secretion measurements show that these specialized functions are maintained for at least 48 h. This study suggests that increasing functional diversity in the population is one strategy macrophages use to respond to conflicting environmental cues. Macrophages can be polarized by in vitro culture stimuli into M1 or M2 cells, but microenvironments in vivo are more complex. Here the authors analyze cultured macrophages stimulated with a combination of M1 and M2 stimuli by single-cell RNA sequencing, machine learning, and single-cell secretion profiling to show a surprising level of heterogeneity of response.

The atomic nucleus is composed of two different kinds of fermions: protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority of fermions (usually neutrons) to have a higher average momentum. Our high-energy electron-scattering measurements using 12C, 27Al, 56Fe, and 208Pb targets show that even in heavy, neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few-body systems to neutron stars and may also be observable experimentally in two-spin–state, ultracold atomic gas systems.

Trigger mechanisms and syn-eruptive processes of Plinian eruptions are poorly understood especially in the case of mafic powerful events. In the last decades, the combined geochemical and textural studies on volcanic rocks have proven to be fundamental tools for exploring the dynamics of magma ascent in volcanic conduits and for improving our ability to interpret volcano-monitoring signals and assess hazard. In this case study, we quantitatively investigate 2D and 3D micro-textural, geochemical, and isotopic features of pyroclastic rocks erupted during the Pomici di Base Plinian eruption (22 ka), the generally acknowledged first and most powerful event of the Somma–Vesuvius volcano. A peculiar aspect of this eruption is its high intensity that remained stable during the entire Plinian phase despite the strong magma compositional variation towards mafic terms. We infer that the transfer of magma towards the surface was intensified by the occurrence of rapid vesiculation pulses driven by limestone assimilation (skarn recycling) during magma ascent through the carbonatic bedrock. We conclude that limestone assimilation can hence be a syn-eruptive process, able to trigger further gas nucleation with deep impact on the eruption intensity, particularly crucial in the case of mafic/intermediate magma compositions.

A search is presented for massive long-lived particles decaying into a muon and two quarks. The dataset consists of proton-proton interactions at centre-of-mass energies of 7 and 8 TeV, corresponding to integrated luminosities of 1 and 2 fb - 1 , respectively. The analysis is performed assuming a set of production mechanisms with simple topologies, including the production of a Higgs-like particle decaying into two long-lived particles. The mass range from 20 to 80  GeV / c 2 and lifetimes from 5 to 100 ps are explored. Results are also interpreted in terms of neutralino production in different R-Parity violating supersymmetric models, with masses in the 23–198 GeV/ c 2 range. No excess above the background expectation is observed and upper limits are set on the production cross-section for various points in the parameter space of theoretical models.

A search is presented for long-lived particles with a mass between 25 and 50 GeV / c 2 and a lifetime between 2 and 500 ps, using proton–proton collision data corresponding to an integrated luminosity of 2.0 fb - 1 , collected by the LHCb detector at centre-of-mass energies of 7 and 8 TeV. The particles are assumed to be pair-produced in the decay of a 125 GeV / c 2 Standard-Model-like Higgs boson. The experimental signature is a single long-lived particle, identified by a displaced vertex with two associated jets. No excess above background is observed and limits are set on the production cross-section as a function of the mass and lifetime of the long-lived particle.

The recently installed internal gas target at LHCb presents exceptional opportunities for an extensive physics program for heavy-ion, hadron, spin, and astroparticle physics. A storage cell placed in the LHC primary vacuum, an advanced Gas Feed System, the availability of multi-TeV proton and ion beams, and the recent upgrade of the LHCb detector make this project unique worldwide. In this paper, we outline the main components of the system, the physics prospects it offers, and the hardware challenges encountered during its implementation. The commissioning phase has yielded promising results, demonstrating that fixed-target collisions can occur concurrently with the collider mode without compromising efficient data acquisition and high-quality reconstruction of beam-gas and beam-beam interactions.

A bstract A comprehensive set of azimuthal single-spin and double-spin asymmetries in semi-inclusive leptoproduction of pions, charged kaons, protons, and antiprotons from transversely polarized protons is presented. These asymmetries include the previously published HERMES results on Collins and Sivers asymmetries, the analysis of which has been extended to include protons and antiprotons and also to an extraction in a three-dimensional kinematic binning and enlarged phase space. They are complemented by corresponding results for the remaining four single-spin and four double-spin asymmetries allowed in the one-photon-exchange approximation of the semi-inclusive deep-inelastic scattering process for target-polarization orientation perpendicular to the direction of the incoming lepton beam. Among those results, significant non-vanishing cos ( ϕ−ϕ S ) modulations provide evidence for a sizable worm-gear (II) distribution, g 1 T q x p T 2 . Most of the other modulations are found to be consistent with zero with the notable exception of large sin ( ϕ S ) modulations for charged pions and K + .

Particle identification at high-energy physics experiments typically relies on classifiers combining different experimental observables. In this document, an innovative approach employing machine learning techniques to describe their dependence from the relevant features is presented. The proposed method is applied to the fixed-target programme at the LHCb experiment, where the sample size of the particle identification calibration channels affects the experimental performance. It is demonstrated to perform better than a model based on the LHCb detailed simulation and to be fast and suitable to a large variety of use cases.

Background. We assessed human immunodeficiency virus (HIV) antibody seroreversion among individuals initiating antiretroviral therapy (ART) during acute/early HIV infection and determined whether seroreversion was associated with loss of cytotoxic T lymphocyte responses. Methods. Subjects in a cohort with acute/early HIV infection (<12 months into infection) who initiated ART within 28 days after study entry and maintained HIV type 1 ribonucleic acid levels of ⩽500 copies/mL for >24 weeks were selected. Two clinically available second-generation enzyme immunoassays (EIAs) and a confirmatory Western blot were used to screen subjects for antibody reversion. Those with negative screening test results underwent additional antibody testing, including a third-generation EIA, and were assessed for cytotoxic T lymphocyte responses. Results. Of 87 subjects identified, 12 (14%) had negative antibody test results at the start of ART; all 12 had seroconversion, although 1 had seroconversion only on a third-generation EIA. Of the 87 subjects, 6 (7%) had seroreversion on at least 1 EIA antibody assay while receiving ART during a median follow-up of 90 weeks. The only clinical predictor of seroreversion was a low baseline “detuned” (less sensitive) antibody. Cytotoxic T lymphocyte responses to HIV Gag peptides were detected in 4 of 5 subjects with seroreversion who could be tested. All 5 who had seroreversion who stopped ART experienced virologic rebound and antibody evolution. Conclusions. HIV antibody seroconversion on second-generation EIA antibody tests may fail to occur when ART is initiated early. Seroreversion was not uncommon among subjects treated early, although cytotoxic T lymphocyte responses to HIV antigens remained detectable in most subjects. Antibody seroreversion did not indicate viral eradication. A third-generation EIA was the most sensitive test for HIV antibodies.

It the last decades, a formalism of transverse momentum dependent parton distribution functions (TMDs) and of generalised parton distributions (GPDs) has been developed in the context of non-perturbative QCD, opening the way for a tomographic imaging of the nucleon structure. TMDs and GPDs provide complementary three-dimensional descriptions of the nucleon structure in terms of parton densities. They thus contribute, with different approaches, to the understanding of the full phase-space distribution of partons. A selection of HERMES results sensitive to TMDs is presented.