Search results for "strong [gravitational lensing]"
showing 10 items of 184 documents
Block and graft copolymers of 2-oxazolines
1994
The cationic ring-opening polymerization of 2-oxazolines is known to be initiated by alkyl halides, Lewis acids and esters of strong acids. The polymerization proceeds by a living mechanism. Numerous block and graft copolymers have already been described. Recently it was found that chloroformates (R-O-CO-CI) are also useful initiators. The mechanism of the initiation and propagation is discussed. This type of initiators allows the synthesis of different novel two-block and three-block copolymers, star-shape polymers, and a graft copolymer with a polyvinylacetate backbone.
The chemistry of [1,2,3]triazolo[1,5- c ]pyrimidine
2001
Abstract Reactions of [1,2,3]triazolo[1,5-c]pyrimidine 2 with some electrophiles and nucleophiles are reported. Triazole ring opening and loss of nitrogen is the principal reaction with electrophiles. With strong acids protonation on N6 competes successfully. Derivatives in which the pyrimidine ring has been opened are obtained in reactions with nucleophiles. No stable simple substitution compounds were found.
Excited states of [3.3](4,4')biphenylophane: the role of charge-transfer excitations in dimers with pi-pi interaction.
2010
The singlet and triplet electronic excitation manifold of [3.3](4,4')biphenylophane (BPP), an intramolecular dimer, and 4,4'-dimethylbiphenyl (DMBP), the corresponding monomer, has been analyzed by employing the approximate coupled-cluster singles and doubles model (CC2). The calculated triplet-triplet and singlet-singlet transient absorption spectra show good agreement with recent experimental results. The calculations suggest a strong interaction of the two biphenyl moieties of BPP in the first singlet and triplet excited states due to the overlapping pi-electron systems, and Forster-Dexter theory for weak coupling cannot be applied. Both the first excited singlet and triplet states of BP…
Cuando la historia está presente: Argumentos a favor de la sociología histórica
2019
Sociology and history have maintained a discontinuous relationship and a permanent discussion. Classical sociology is intrinsically historical, but after the first theoretical synthesis the dialogue between both disciplines was extinguished and it has often been necessary to defend the need for the historical view in sociology from the margins of the dominant paradigm. However, as a specialty or subdiscipline, historical sociology has consolidated its own academic space and a strong theoretical, methodological and conceptual body. In Spain this process of institutionalization has not yet success. In this article we expose a few arguments in defense of historical sociology, both theoretical …
NuSTEC White Paper: Status and challenges of neutrino–nucleus scattering
2018
International audience; The precise measurement of neutrino properties is among the highest priorities in fundamental particle physics, involving many experiments worldwide. Since the experiments rely on the interactions of neutrinos with bound nucleons inside atomic nuclei, the planned advances in the scope and precision of these experiments require a commensurate effort in the understanding and modeling of the hadronic and nuclear physics of these interactions, which is incorporated as a nuclear model in neutrino event generators. This model is essential to every phase of experimental analyses and its theoretical uncertainties play an important role in interpreting every result.In this Wh…
Precision measurement of the mass difference between light nuclei and anti-nuclei
2015
The measurement of the mass differences for systems bound by the strong force has reached a very high precision with protons and anti-protons. The extension of such measurement from (anti-)baryons to (anti-)nuclei allows one to probe any difference in the interactions between nucleons and anti-nucleons encoded in the (anti-)nuclei masses. This force is a remnant of the underlying strong interaction among quarks and gluons and can be described by effective theories, but cannot yet be directly derived from quantum chromodynamics. Here we report a measurement of the difference between the ratios of the mass and charge of deuterons and anti-deuterons, and $^{3}{\rm He}$ and $^3\overline{\rm He}…
Development and validation of an intrinsic capacity composite score in the Longitudinal Aging Study Amsterdam: a formative approach
2023
Abstract Background Intrinsic capacity (IC) defined by the WHO refers to the composite of five domains of capacities. So far, developing and validating a standardized overall score of the concept have been challenging partly because its conceptual framework has been unclear. We consider that a person’s IC is determined by its domain-specific indicators suggesting a formative measurement model. Aims To develop an IC score applying a formative approach and assess its validity. Methods The study sample (n = 1908) consisted of 57–88-year-old participants from the Longitudinal Aging Study Amsterdam (LASA). We used logistic regression models to select the indicators to the IC score with 6-year fu…
Approach to equilibrium of a quarkonium in a quark-gluon plasma
2018
We derive equations of motion for the reduced density matrix of a heavy quarkonium in contact with a quark-gluon plasma in thermal equilibrium. These equations allow in particular a proper treatment of the regime when the temperature of the plasma is comparable to the binding energy of the quarkonium. These equations are used to study how the quarkonium approaches equilibrium with the plasma, and we discuss the corresponding entropy increase, or free energy decrease, depending on the temperature regime. The effect of collisions can be accounted for by the generalization of the imaginary potential introduced in previous studies, and from which collision rates are derived. An important outcom…
Review of Particle Physics
2020
The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 2,143 new measurements from 709 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. Particle properties and search limits are listed in Summary Tables. We give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, …
Twenty-three unsolved problems in hydrology (UPH) – a community perspective
2019
Publisher's version (útgefin grein)