Hunting for Dark Particles with Gravitational Waves

The LIGO observation of gravitational waves from a binary black hole merger has begun a new era in fundamental physics. If new dark sector particles, be they bosons or fermions, can coalesce into exotic compact objects (ECOs) of astronomical size, then the first evidence for such objects, and their underlying microphysical description, may arise in gravitational wave observations. In this work we study how the macroscopic properties of ECOs are related to their microscopic properties, such as dark particle mass and couplings. We then demonstrate the smoking gun exotic signatures that would provide observational evidence for ECOs, and hence new particles, in terrestrial gravitational wave observatories. Finally, we discuss how gravitational waves can test a core concept in general relativity: Hawking's area theorem.Comment: 44 pages, 14 figures. Revised version to appear in JCA

Self-assembly of triblock copolymers in aqueous solution

Indexación: ScieloThe aggregation of PE4VP-b-PS-b-PE4VP block copolymers was studied in aqueous solution. Triblock copolymers P4VP-b-PS-b-P4VP were synthesized by sequential anionic polymerization of poly(styrene) and poly(4-vinylpirydine) using sodium naphthalene as a bifunctional initiator. Subsequently, the 4-vinylpyridine units were quaternized with ethyl bromide to obtain cationic PE4VP-b-PS-b-PE4VP block copolymers. Both star and crew-cut micelles were formed. The concentrations at which micelles are formed cmc were determined, by steady-state and time-resolved fluorescence probing methods, as a function of quatemization degree. The results indicate that cmc of crew-cut micelles increases with increasing charge density of the PE4VP blocks. For star micelles there is not a clear dependency of cmc with the percentage of quatemization. The lifetime of pyrene fluorescence and the ratio I1/I3 were determined at concentrations of copolymers well above the cmc, and the results show that the location of pyrene into the micelle changes with the charge density of the micelle corona. The micropolarity sensed by pyrene decreases with increasing quatemization degree. The presence of aggregates was confirmed by transmission electronic microscopy.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072008000200013&lng=es&nrm=is

Clockwork / Linear Dilaton: Structure and Phenomenology

The linear dilaton geometry in five dimensions, rediscovered recently in the continuum limit of the clockwork model, may offer a solution to the hierarchy problem which is qualitatively different from other extra-dimensional scenarios and leads to distinctive signatures at the LHC. We discuss the structure of the theory, in particular aspects of naturalness and UV completion, and then explore its phenomenology, suggesting novel strategies for experimental searches. In particular, we propose to analyze the diphoton and dilepton invariant mass spectra in Fourier space in order to identify an approximately periodic structure of resonant peaks. Among other signals, we highlight displaced decays from resonantly-produced long-lived states and high-multiplicity final states from cascade decays of excited gravitons.Comment: 39 pages + appendices, 27 figures; v2: minor improvements; published versio

Search for partial resistance to leaf rust in a collection of ancient Spanish wheats

A collection of 917 accessions of Spanish durum and bread wheat was screened for resistance to leaf rust (Puccinia triticina) under field conditions at three locations. Resistance levels ranged from very low to very high, high susceptibility being most frequent. Relative disease severity (referred to the most susceptible accession = 100 %) was lower than 20 % in about 6 % of the accessions in each location. In the collection most of the lines (84 %)displayed a susceptible infection type. A final selection of seven accessions (one of them durum) displaying low severity level in the field and high infection type in a growth chamber was chosen for further studies. High levels of partial resistant with longer latency period and high percentage of early aborted colonies without necrosis were found. They might be used in breeding programmes

Adaptation of robot behaviour through online evolution and neuromodulated learning

We propose and evaluate a novel approach to the online synthesis of neural controllers for autonomous robots. We combine online evolution of weights and network topology with neuromodulated learning. We demonstrate our method through a series of simulation-based experiments in which an e-puck-like robot must perform a dynamic concurrent foraging task. In this task, scattered food items periodically change their nutritive value or become poisonous. Our results show that when neuromodulated learning is employed, neural controllers are synthesised faster than by evolution alone. We demonstrate that the online evolutionary process is capable of generating controllers well adapted to the periodic task changes. An analysis of the evolved networks shows that they are characterised by specialised modulatory neurons that exclusively regulate the output neurons.info:eu-repo/semantics/acceptedVersio

Site specific spin dynamics in BaFe2As2: tuning the ground state by orbital differentiation

The role of orbital differentiation on the emergence of superconductivity in the Fe-based superconductors remains an open question to the scientific community. In this investigation, we employ a suitable microscopic spin probe technique, namely Electron Spin Resonance (ESR), to investigate this issue on selected chemically substituted BaFe$_{2}$As$_{2}$ single crystals. As the spin-density wave (SDW) phase is suppressed, we observe a clear increase of the Fe 3$d$ bands anisotropy along with their localization at the FeAs plane. Such an increase of the planar orbital content interestingly occurs independently on the chemical substitution responsible for suppressing the SDW phase. As a consequence, the magnetic fluctuations combined with the resultant particular symmetry of the Fe 3$d$ bands are propitious ingredients to the emergence of superconductivity in this class of materials.Comment: 6 pages, 5 figure

Active Learning Methodologies in Teacher Training for Cultural Sustainability

Within the framework of sustainable development, the concept of cultural heritage is linked to the heritage awareness of a specific spatial context, and to the conservation of collective memory. Despite the clear interest in cultural sustainability, the lack of research devoted to interpreting different teaching methods for transmitting patrimonial assets and preserving natural heritage is noteworthy. For this reason, the present study takes various scientific contributions as the background for considering sustainable education as a fundamental instrument to recover and conserve heritage resources, both from an informative and educational point of view. The aim of this study was to assess the training of new teachers in terms of the particular skills needed to develop active learning methods related to the teaching of heritage sustainability. The research sample consisted of 488 students in the Degree in Primary Education program. The methodology combined both qualitative and quantitative techniques, to obtain information from both observation and an opinion survey given to the students. The results show several opinions related to achieving and facilitating the implementation of innovative methodologies, due to a lack of initial university training. Generally speaking, this work provided an opportunity for students to analyze a series of prejudices regarding their working methods, and to overcome excessive theorization in their university studies

second line egfr inhibitors in ras mutant metastatic colorectal cancer the plasma ras wild type window of opportunity

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