Explore the vast range of titles available.

Atmospheric particles have several impacts on health and the environment, especially in urban areas. Parts of those particles are not fresh and have undergone atmospheric chemical and physical processes. Due to a lack of representativeness of experimental conditions and experimental artifacts such as particle wall losses in chambers, there are uncertainties on the effects of physical processes (condensation, nucleation and coagulation) and their role in particle evolution from modern vehicles. This study develops a new method to correct wall losses, accounting for size dependence and experiment-to-experiment variations. It is applied to the evolution of fresh diesel exhaust particles to characterize the physical processes which they undergo. The correction method is based on the black carbon decay and a size-dependent coefficient to correct particle distributions. Six diesel passenger cars, Euro 3 to Euro 6, were driven on a chassis dynamometer with Artemis Urban cold start and Artemis Motorway cycles. Exhaust was injected in an 8 m3 chamber with Teflon walls. The physical evolution of particles was characterized during 6 to 10 h. Increase in particle mass is observed even without photochemical reactions due to the presence of intermediate-volatility organic compounds and semi-volatile organic compounds. These compounds were quantified at emission and induce a particle mass increase up to 17 % h−1, mainly for the older vehicles (Euro 3 and Euro 4). Condensation is 4 times faster when the available particle surface is multiplied by 6.5. If initial particle number concentration is below [8–9] × 104 cm−3, a nucleation mode seems to be present but not measured by a scanning mobility particle sizer (SMPS). The growth of nucleation-mode particles results in an increase in measured [PN]. Above this threshold, particle number concentration decreases due to coagulation, up to −27 % h−1. Under those conditions, the chamber and experimental setup are well suited to characterizing and quantifying the process of coagulation.

By advancing spring leaf flush and ensuing food availability, climatic warming results in a mismatch between the timing of peak food supply and nestling demand, shifting the optimal time for reproduction in birds. Two populations of blue tits ( Parus caeruleus ) that breed at different dates in similar, but spatially distinct, habitat types in Corsica and southern France provide a unique opportunity to quantify the energetic and fitness consequences when breeding is mismatched with local productivity. As food supply and demand become progressively mismatched, the increased cost of rearing young pushes the metabolic effort of adults beyond their apparent sustainable limit, drastically reducing the persistence of adults in the breeding population. We provide evidence that the economics of parental foraging and limits to sustainable metabolic effort are key selective forces underlying synchronized seasonal breeding and long-term shifts in breeding date in response to climatic change.

The αvβ3 integrin plays an important role in tumour-induced angiogenesis, tumour proliferation, survival and metastasis. The tetrameric RGD-based peptide, regioselectively addressable functionalized template-(cyclo-[RGDfK])4 (RAFT-RGD), specifically targets the αvβ3 integrin in vitro and in vivo. The aim of this study was to evaluate the therapeutic potential of RAFT-RGD radiolabelled with β(-) emitters in a nude mouse model of αvβ3 integrin-expressing tumours. Biodistribution and SPECT/CT imaging studies were performed after injection of (90)Y-RAFT-RGD or (177)Lu-RAFT-RGD in nude mice subcutaneously xenografted with αvβ3 integrin-expressing U-87 MG cells. Experimental targeted radionuclide therapy with (90)Y-RAFT-RGD or (177)Lu-RAFT-RGD and (90)Y-RAFT-RAD or (177)Lu-RAFT-RAD (nonspecific controls) was evaluated by intravenous injection of the radionuclides into mice bearing αvβ3 integrin-expressing U-87 MG tumours of different sizes (small or large) or bearing TS/A-pc tumours that do not express αvβ3. Tumour volume doubling time was used to evaluate the efficacy of each treatment. Injection of 37 MBq of (90)Y-RAFT-RGD into mice with large αvβ3-positive tumours or 37 MBq of (177)Lu-RAFT-RGD into mice with small αvβ3-positive tumours caused significant growth delays compared to mice treated with 37 MBq of (90)Y-RAFT-RAD or 37 MBq of (177)Lu-RAFT-RAD or untreated mice. In contrast, injection of 30 MBq of (90)Y-RAFT-RGD had no effect on the growth of αvβ3-negative tumours. (90)Y-RAFT-RGD and (177)Lu-RAFT-RGD are potent agents targeting αvβ3-expressing tumours for internal targeted radiotherapy.

Conventional, hadronic matter consists of baryons and mesons made of three quarks and a quark–antiquark pair, respectively 1 , 2 . Here, we report the observation of a hadronic state containing four quarks in the Large Hadron Collider beauty experiment. This so-called tetraquark contains two charm quarks, a u ¯ and a d ¯ quark. This exotic state has a mass of approximately 3,875 MeV and manifests as a narrow peak in the mass spectrum of D 0 D 0 π + mesons just below the D *+ D 0 mass threshold. The near-threshold mass together with the narrow width reveals the resonance nature of the state. The LHCb Collaboration reports the observation of an exotic, narrow, tetraquark state that contains two charm quarks, an up antiquark and a down antiquark.

Quantum chromodynamics, the theory of the strong force, describes interactions of coloured quarks and gluons and the formation of hadronic matter. Conventional hadronic matter consists of baryons and mesons made of three quarks and quark-antiquark pairs, respectively. Particles with an alternative quark content are known as exotic states. Here a study is reported of an exotic narrow state in the D 0 D 0 π + mass spectrum just below the D *+ D 0 mass threshold produced in proton-proton collisions collected with the LHCb detector at the Large Hadron Collider. The state is consistent with the ground isoscalar T c c + tetraquark with a quark content of c c u ¯ d ¯ and spin-parity quantum numbers J P  = 1 + . Study of the DD mass spectra disfavours interpretation of the resonance as the isovector state. The decay structure via intermediate off-shell D *+ mesons is consistent with the observed D 0 π + mass distribution. To analyse the mass of the resonance and its coupling to the D * D system, a dedicated model is developed under the assumption of an isoscalar axial-vector T c c + state decaying to the D * D channel. Using this model, resonance parameters including the pole position, scattering length, effective range and compositeness are determined to reveal important information about the nature of the T c c + state. In addition, an unexpected dependence of the production rate on track multiplicity is observed. The existence and properties of tetraquark states with two heavy quarks and two light antiquarks have been widely debated. Here, the authors use a unitarized model to study the properties of an exotic narrow state compatible with a doubly charmed tetraquark.

The standard model of particle physics currently provides our best description of fundamental particles and their interactions. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Previous measurements have shown that a wide range of particle decays are consistent with this principle of lepton universality. This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on proton–proton collision data collected with the LHCb detector at CERN’s Large Hadron Collider. The measurements are of processes in which a beauty meson transforms into a strange meson with the emission of either an electron and a positron, or a muon and an antimuon. If confirmed by future measurements, this violation of lepton universality would imply physics beyond the standard model, such as a new fundamental interaction between quarks and leptons. The Large Hadron Collider beauty collaboration reports a test of lepton flavour universality in decays of bottom mesons into strange mesons and a charged lepton pair, finding evidence of a violation of this principle postulated in the standard model.

A bstract The W boson mass is measured using proton-proton collision data at s = 13 TeV corresponding to an integrated luminosity of 1.7 fb − 1 recorded during 2016 by the LHCb experiment. With a simultaneous fit of the muon q/p T distribution of a sample of W → μν decays and the ϕ * distribution of a sample of Z → μμ decays the W boson mass is determined to be m w = 80354 ± 23 stat ± 10 exp ± 17 theory ± 9 PDF MeV , where uncertainties correspond to contributions from statistical, experimental systematic, theoretical and parton distribution function sources. This is an average of results based on three recent global parton distribution function sets. The measurement agrees well with the prediction of the global electroweak fit and with previous measurements.

A bstract An angular analysis of the rare decay B s 0 → ϕμ + μ − is presented, using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 8.4 fb − 1 . The observables describing the angular distributions of the decay B s 0 → ϕμ + μ − are determined in regions of q 2 , the square of the dimuon invariant mass. The results are consistent with Standard Model predictions.

A bstract The isospin asymmetries of B → Kμ + μ − and B → K * μ + μ − decays and the partial branching fractions of the B 0 → K 0 μ + μ − , B + → K + μ + μ − and B + → K *+ μ + μ − decays are measured as functions of the dimuon mass squared, q 2 . The data used correspond to an integrated luminosity of 3 fb −1 from proton-proton collisions collected with the LHCb detector at centre-of-mass energies of 7 TeV and 8 TeV in 2011 and 2012, respectively. The isospin asymmetries are both consistent with the Standard Model expectations. The three measured branching fractions favour lower values than their respective theoretical predictions, however they are all individually consistent with the Standard Model.

1. Identifying how selection shapes life-history traits by causally relating environment to phenotype, performance and fitness has often proven elusive due to limitations of classical analysis methods, which only identify covariance in traits, and to the difficulties in experimentally manipulating environment to expose cause and effect in wild populations. 2. In an approach resembling the experimental method common to all modern research, structural equation modelling can not only identify covariance in traits, but also test hypotheses of direct and indirect causal paths that tie environment to phenotypes and fitness through natural selection. Here, we use novel confirmatory path analyses and a long-term study of Corsican blue tits to analyse the interactions between environmental variables (prey abundance and ectoparasite load), phenotypic traits (mass and haematocrit), physiological performance (aerobic capacity) and nestling recruitment. 3. Our analyses show that an antagonistic interaction between ectoparasites and food abundance sets tissue development and oxygen carrying capacity of blood at fledging, and that identical paths link these variables to physiological performance and recruitment. 4. This study suggests that metabolic capacity at fledging may be important in determining subsequent recruitment and unmasks subtle fitness costs of an ectoparasite.