Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Engineering PD-1-Presenting Platelets for Cancer Immunotherapy

Radical surgery still represents the treatment choice for several malignancies. However, local and distant tumor relapses remain the major causes of treatment failure, indicating that a postsurgery consolidation treatment is necessary. Immunotherapy with checkpoint inhibitors has elicited impressive clinical responses in several types of human malignancies and may represent the ideal consolidation treatment after surgery. Here, we genetically engineered platelets from megakaryocyte (MK) progenitor cells to express the programmed cell death protein 1 (PD-1). The PD-1 platelet and its derived microparticle could accumulate within the tumor surgical wound and revert exhausted CD8⁺ T cells, leading to the eradication of residual tumor cells. Furthermore, when a low dose of cyclophosphamide (CP) was loaded into PD-1-expressing platelets to deplete regulatory T cells (Tregs), an increased frequency of reinvigorated CD8⁺ lymphocyte cells was observed within the postsurgery tumor microenvironment, directly preventing tumor relapse

Enhanced Antiglioblastoma Efficacy of Neovasculature and Glioma Cells Dual Targeted Nanoparticles

Combining treatment of anticancer cells and antiangiogenesis is considered to be a potential targeted strategy for brain glioblastoma therapy. In this study, by utilizing the overexpression of Interleukin 13 receptor α2 (IL-13Rα2) on the glioma cells and heparan sulfate on neovascular endothelial cells, we developed a paclitaxel (PTX) loaded Pep-1 and CGKRK peptide-modified PEG–PLGA nanoparticle (PC-NP-PTX) for glioma cells and neovasculature dual-targeted chemotherapy to enhance the antiglioma efficacy. There were significant differences both on the enhancement of cellular uptake in HUVEC and C6 cells and on the improvement of <i>in vitro</i> antiglioma activity in the respect of proliferation, tumor spheroid growth, tube formation, and migration between PC-NP-PTX and Taxol and NP-PTX. As for C6 cells, the IC₅₀ were 3.59 ± 0.056, 2.37 ± 0.044, 1.38 ± 0.028, 1.82 ± 0.035, and 1.00 ± 0.016 μg/mL of Taxol, NP-PTX, Pep-NP-PTX, CGKRK-NP-PTX, and PC-NP-PTX, and for HUVEC cells, the IC₅₀ were 0.44 ± 0.006, 0.33 ± 0.005, 0.25 ± 0.005, 0.19 ± 0.004, and 0.16 ± 0.004 μg/mL of Taxol, NP-PTX, Pep-NP-PTX, CGKRK-NP-PTX, and PC-NP-PTX, respectively. <i>In vivo</i> distribution assays confirmed that PC-NP-PTX targeted and accumulated effectively at glioma site. PC-NP-PTX showed a longer median survival time of 61 days when compared with Taxol (22 days), NP-PTX (24 days), Pep-NP-PTX (32 days), and CGKRK-NP-PTX (34 days). The <i>in vivo</i> antiglioma efficacy and safety evaluation showed PC-NP-PTX significantly enhanced the antiglioma efficacy and displayed negligible acute toxicity

Comparison of a new minimum contact locking plate and the limited contact dynamic compression plate in an osteoporotic fracture model

The purpose of this study was to investigate the biomechanical properties of a new minimum contact locking plate (MC-LP) compared with the limited contact dynamic compression plate (LC-DCP). Eighteen pairs of fresh human osteoporotic cadaver radii were equally divided into three groups. Each specimen was tested in each of the following force applications: anteroposterior (AP) four point bending, mediolateral (ML) four point bending, and torsion. A 10-mm gap osteotomy model was used to simulate a comminuted diaphyseal radial fracture. For each pair, one radius received a limited contact dynamic compression plate (LC-DCP) and the contralateral radius was fixed with a minimum contact locking plate (MC-LP). Specimens were tested in nondestructive four point bending and torsion on an electronic universal material testing system. The results indicate that the MC-LP system is significantly more stable than the LC-DCP system when tested in four point bending and torsion in an osteoporotic comminuted radial diaphyseal fracture model

Searches for the ZγZ\gamma decay mode of the Higgs boson and for new high-mass resonances in pppp collisions at s=13\sqrt{s} = 13 TeV with the ATLAS detector

International audienceThis article presents searches for the Zγ decay of the Higgs boson and for narrow high-mass resonances decaying to Zγ, exploiting Z boson decays to pairs of electrons or muons. The data analysis uses 36.1 fb$^{−1}$ of pp collisions at $\sqrt{s}=13$ recorded by the ATLAS detector at the CERN Large Hadron Collider. The data are found to be consistent with the expected Standard Model background. The observed (expected — assuming Standard Model pp → H → Zγ production and decay) upper limit on the production cross section times the branching ratio for pp → H → Zγ is 6.6. (5.2) times the Standard Model prediction at the 95% confidence level for a Higgs boson mass of 125.09 GeV. In addition, upper limits are set on the production cross section times the branching ratio as a function of the mass of a narrow resonance between 250 GeV and 2.4 TeV, assuming spin-0 resonances produced via gluon-gluon fusion, and spin-2 resonances produced via gluon-gluon or quark-antiquark initial states. For high-mass spin-0 resonances, the observed (expected) limits vary between 88 fb (61 fb) and 2.8 fb (2.7 fb) for the mass range from 250 GeV to 2.4 TeV at the 95% confidence level

Search for direct top squark pair production in final states with two leptons in s=13\sqrt{s} = 13 TeV pppp collisions with the ATLAS detector

International audienceThe results of a search for direct pair production of top squarks in events with two opposite-charge leptons (electrons or muons) are reported, using $36.1~\hbox {fb}^{-1}$ of integrated luminosity from proton–proton collisions at $\sqrt{s}=13$ TeV collected by the ATLAS detector at the Large Hadron Collider. To cover a range of mass differences between the top squark $\tilde{t}$ and lighter supersymmetric particles, four possible decay modes of the top squark are targeted with dedicated selections: the decay $\tilde{t} \rightarrow b \tilde{\chi }_{1}^{\pm }$ into a b-quark and the lightest chargino with $\tilde{\chi }_{1}^{\pm } \rightarrow W \tilde{\chi }_{1}^{0}$ , the decay $\tilde{t} \rightarrow t \tilde{\chi }_{1}^{0}$ into an on-shell top quark and the lightest neutralino, the three-body decay $\tilde{t} \rightarrow b W \tilde{\chi }_{1}^{0}$ and the four-body decay $\tilde{t} \rightarrow b \ell \nu \tilde{\chi }_{1}^{0}$ . No significant excess of events is observed above the Standard Model background for any selection, and limits on top squarks are set as a function of the $\tilde{t}$ and $\tilde{\chi }_{1}^{0}$ masses. The results exclude at 95% confidence level $\tilde{t}$ masses up to about 720 GeV, extending the exclusion region of supersymmetric parameter space covered by previous searches

Searches for the ZγZ\gamma decay mode of the Higgs boson and for new high-mass resonances in pppp collisions at s=13\sqrt{s} = 13 TeV with the ATLAS detector

International audienceThis article presents searches for the Zγ decay of the Higgs boson and for narrow high-mass resonances decaying to Zγ, exploiting Z boson decays to pairs of electrons or muons. The data analysis uses 36.1 fb$^{−1}$ of pp collisions at $\sqrt{s}=13$ recorded by the ATLAS detector at the CERN Large Hadron Collider. The data are found to be consistent with the expected Standard Model background. The observed (expected — assuming Standard Model pp → H → Zγ production and decay) upper limit on the production cross section times the branching ratio for pp → H → Zγ is 6.6. (5.2) times the Standard Model prediction at the 95% confidence level for a Higgs boson mass of 125.09 GeV. In addition, upper limits are set on the production cross section times the branching ratio as a function of the mass of a narrow resonance between 250 GeV and 2.4 TeV, assuming spin-0 resonances produced via gluon-gluon fusion, and spin-2 resonances produced via gluon-gluon or quark-antiquark initial states. For high-mass spin-0 resonances, the observed (expected) limits vary between 88 fb (61 fb) and 2.8 fb (2.7 fb) for the mass range from 250 GeV to 2.4 TeV at the 95% confidence level

Measurements of ttˉt\bar{t} differential cross-sections of highly boosted top quarks decaying to all-hadronic final states in pppp collisions at s=13 \sqrt{s}=13\, TeV using the ATLAS detector

Measurements are made of differential cross-sections of highly boosted pair-produced top quarks as a function of top-quark and $t\bar{t}$ system kinematic observables using proton--proton collisions at a center-of-mass energy of $\sqrt{s} = 13$ TeV. The data set corresponds to an integrated luminosity of $36.1$ fb$^{-1}$, recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Events with two large-radius jets in the final state, one with transverse momentum $p_{\rm T} > 500$ GeV and a second with $p_{\rm T}>350$ GeV, are used for the measurement. The top-quark candidates are separated from the multijet background using jet substructure information and association with a $b$-tagged jet. The measured spectra are corrected for detector effects to a particle-level fiducial phase space and a parton-level limited phase space, and are compared to several Monte Carlo simulations by means of calculated $\chi^2$ values. The cross-section for $t\bar{t}$ production in the fiducial phase-space region is $292 \pm 7 \ \rm{(stat)} \pm 76 \rm{(syst)}$ fb, to be compared to the theoretical prediction of $384 \pm 36$ fb

Measurements of ttˉt\bar{t} differential cross-sections of highly boosted top quarks decaying to all-hadronic final states in pppp collisions at s=13 \sqrt{s}=13\, TeV using the ATLAS detector

Measurements are made of differential cross-sections of highly boosted pair-produced top quarks as a function of top-quark and $t\bar{t}$ system kinematic observables using proton--proton collisions at a center-of-mass energy of $\sqrt{s} = 13$ TeV. The data set corresponds to an integrated luminosity of $36.1$ fb$^{-1}$, recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Events with two large-radius jets in the final state, one with transverse momentum $p_{\rm T} > 500$ GeV and a second with $p_{\rm T}>350$ GeV, are used for the measurement. The top-quark candidates are separated from the multijet background using jet substructure information and association with a $b$-tagged jet. The measured spectra are corrected for detector effects to a particle-level fiducial phase space and a parton-level limited phase space, and are compared to several Monte Carlo simulations by means of calculated $\chi^2$ values. The cross-section for $t\bar{t}$ production in the fiducial phase-space region is $292 \pm 7 \ \rm{(stat)} \pm 76 \rm{(syst)}$ fb, to be compared to the theoretical prediction of $384 \pm 36$ fb