Search Results Heading

MBRLSearchResults

mbrl.module.common.modules.added.book.to.shelf
Title added to your shelf!
View what I already have on My Shelf.
Oops! Something went wrong.
Oops! Something went wrong.
While trying to add the title to your shelf something went wrong :( Kindly try again later!
Are you sure you want to remove the book from the shelf?
Oops! Something went wrong.
Oops! Something went wrong.
While trying to remove the title from your shelf something went wrong :( Kindly try again later!
    Done
    Filters
    Reset
  • Discipline
      Discipline
      Clear All
      Discipline
  • Is Peer Reviewed
      Is Peer Reviewed
      Clear All
      Is Peer Reviewed
  • Series Title
      Series Title
      Clear All
      Series Title
  • Item Type
      Item Type
      Clear All
      Item Type
  • Year
      Year
      Clear All
      From:
      -
      To:
  • More Filters
      More Filters
      Clear All
      More Filters
      Is Full-Text Available
    • Subject
    • Country Of Publication
    • Publisher
    • Source
    • Target Audience
    • Language
    • Place of Publication
    • Contributors
    • Location
4,868 result(s) for "Martin, Fernando"
Sort by:
David Beckham
Learn about David Beckham - the much-loved footballer who grew up dreaming of scoring goals for his favourite team. He spent years playing for local clubs and joined Manchester United's youth academy as a teen. After entering the first squad under the leadership of Alex Ferguson, it soon became clear that David was a star on the pitch. He won the Premier League, FA Cup and Champions League all in one season, a pioneering feat! He went on to become captain of the England team and a hero to people across the country. A footballing legend who is loved by all, David's achievements are the culmination of a lifetime of hard work and talent. This book features quirky illustrations and extra facts at the back, including a biographical timeline with historical photos and a detailed profile of the footballer's life.
Money, Banking, and Financial Markets
The fact that money, banking, and financial markets interact in important ways seems self-evident. The theoretical nature of this interaction, however, has not been fully explored. To this end, we integrate the Diamond (1997, Journal of Political Economy 105, 928–956) model of banking and financial markets with the Lagos and Wright (2005, Journal of Political Economy 113, 463–484) dynamic model of monetary exchange—a union that bears a framework in which fractional reserve banks emerge in equilibrium, where bank assets are funded with liabilities made demandable in government money, where the terms of bank deposit contracts are affected by the liquidity insurance available in financial markets, where banks are subject to runs, and where a central bank has a meaningful role to play, both in terms of inflation policy and as a lender of last resort. Among other things, the model provides a rationale for nominal deposit contracts combined with a central bank lender-of-last-resort facility to promote efficient liquidity insurance and a panic-free banking system.
Reconstruction and control of a time-dependent two-electron wave packet
The dynamics of two correlated electrons can be reconstructed from the quantum interference of low-lying doubly excited states in helium, as observed in attosecond transient-absorption spectra, and can be controlled by tuning the interaction with a visible laser field of variable intensity. Two-electron motion probed Although the concerted motion of two or more bound electrons controls all chemical reactions, understanding and probing of such electron dynamics remains challenging. The motion of single electrons has been observed with attosecond time resolution, but comparable experiments on two-electron motion have not yet been realized. Christian Ott and colleagues now show that the dynamics of two correlated electrons in helium can be reconstructed from attosecond transient-absorption spectra measured with unprecedented high spectral resolution and in the presence of an intensity-tuneable visible laser field. Future experiments using the same approach are expected to provide benchmark data for testing theory, and might even make it possible to probe metastable electronic transition states that are at the heart of fundamental chemical reactions. The concerted motion of two or more bound electrons governs atomic 1 and molecular 2 , 3 non-equilibrium processes including chemical reactions, and hence there is much interest in developing a detailed understanding of such electron dynamics in the quantum regime. However, there is no exact solution for the quantum three-body problem, and as a result even the minimal system of two active electrons and a nucleus is analytically intractable 4 . This makes experimental measurements of the dynamics of two bound and correlated electrons, as found in the helium atom, an attractive prospect. However, although the motion of single active electrons and holes has been observed with attosecond time resolution 5 , 6 , 7 , comparable experiments on two-electron motion have so far remained out of reach. Here we show that a correlated two-electron wave packet can be reconstructed from a 1.2-femtosecond quantum beat among low-lying doubly excited states in helium. The beat appears in attosecond transient-absorption spectra 5 , 7 , 8 , 9 measured with unprecedentedly high spectral resolution and in the presence of an intensity-tunable visible laser field. We tune the coupling 10 , 11 , 12 between the two low-lying quantum states by adjusting the visible laser intensity, and use the Fano resonance as a phase-sensitive quantum interferometer 13 to achieve coherent control of the two correlated electrons. Given the excellent agreement with large-scale quantum-mechanical calculations for the helium atom, we anticipate that multidimensional spectroscopy experiments of the type we report here will provide benchmark data for testing fundamental few-body quantum dynamics theory in more complex systems. They might also provide a route to the site-specific measurement and control of metastable electronic transition states that are at the heart of fundamental chemical reactions.
Open questions in attochemistry
Attosecond science is nowadays a well-established research field, and table-top attosecond sources based on high-harmonic generation are routinely used to access electronic motion in matter at its natural time scale. Here, the authors describe a new way of doing chemistry—attochemistry—by directly acting on the electronic motion, and discuss a few key open questions in this emerging field.
Accounting for forest condition in Europe based on an international statistical standard
Covering 35% of Europe’s land area, forest ecosystems play a crucial role in safeguarding biodiversity and mitigating climate change. Yet, forest degradation continues to undermine key ecosystem services that forests deliver to society. Here we provide a spatially explicit assessment of the condition of forest ecosystems in Europe following a United Nations global statistical standard on ecosystem accounting, adopted in March 2021. We measure forest condition on a scale from 0 to 1, where 0 represents a degraded ecosystem and 1 represents a reference condition based on primary or protected forests. We show that the condition across 44 forest types averaged 0.566 in 2000 and increased to 0.585 in 2018. Forest productivity and connectivity are comparable to levels observed in undisturbed or least disturbed forests. One third of the forest area was subject to declining condition, signalled by a reduction in soil organic carbon, tree cover density and species richness of threatened birds. Our findings suggest that forest ecosystems will need further restoration, improvements in management and an extended period of recovery to approach natural conditions. Monitoring ecosystem conditions in quantitative and standardized ways could facilitate transnational coordination of conservation and land management policies. Here, the authors use a spatially explicit ecosystem accounting approach to assess the state of European forests and recent trends.
Imaging and controlling coherent phonon wave packets in single graphene nanoribbons
The motion of atoms is at the heart of any chemical or structural transformation in molecules and materials. Upon activation of this motion by an external source, several (usually many) vibrational modes can be coherently coupled, thus facilitating the chemical or structural phase transformation. These coherent dynamics occur on the ultrafast timescale, as revealed, e.g., by nonlocal ultrafast vibrational spectroscopic measurements in bulk molecular ensembles and solids. Tracking and controlling vibrational coherences locally at the atomic and molecular scales is, however, much more challenging and in fact has remained elusive so far. Here, we demonstrate that the vibrational coherences induced by broadband laser pulses on a single graphene nanoribbon (GNR) can be probed by femtosecond coherent anti-Stokes Raman spectroscopy (CARS) when performed in a scanning tunnelling microscope (STM). In addition to determining dephasing (~440 fs) and population decay times (~1.8 ps) of the generated phonon wave packets, we are able to track and control the corresponding quantum coherences, which we show to evolve on time scales as short as ~70 fs. We demonstrate that a two-dimensional frequency correlation spectrum unequivocally reveals the quantum couplings between different phonon modes in the GNR. Here, the authors demonstrate that the atomic motion induced by broadband laser pulses in a single graphene nanoribbon (GNR) can be tracked by femtosecond coherent anti-Stokes Raman spectroscopy (CARS) when performed in a scanning tunnelling microscope (STM).
Attosecond delays between dissociative and non-dissociative ionization of polyatomic molecules
The interplay between electronic and nuclear motions in molecules is a central concept in molecular science. To what extent it influences attosecond photoionization delays is an important, still unresolved question. Here, we apply attosecond electron-ion coincidence spectroscopy and advanced calculations that include both electronic and nuclear motions to study the photoionization dynamics of CH 4 and CD 4 molecules. These molecules are known to feature some of the fastest nuclear dynamics following photoionization. Remarkably, we find no measurable delay between the photoionization of CH 4 and CD 4 , neither experimentally nor theoretically. However, we measure and calculate delays of up to 20 as between the dissociative and non-dissociative photoionization of the highest-occupied molecular orbitals of both molecules. Experiment and theory are in quantitative agreement. These results show that, in the absence of resonances, even the fastest nuclear motion does not substantially influence photoionization delays, but identify a previously unknown signature of nuclear motion in dissociative-ionization channels. These findings have important consequences for the design and interpretation of attosecond chronoscopy in molecules, clusters, and liquids. The role of nuclear motion on photoionization delays is an interesting open question. Here the authors study photoionization delays in dissociative and non-dissociative ionization of a polyatomic molecule and explore the effect of isotopic substitution.
Direct tracking of H2 roaming reaction in real time
Roaming is an unconventional type of molecular reaction where fragments, instead of immediately dissociating, remain weakly bound due to long-range Coulombic interactions. Due to its prevalence and ability to form new molecular compounds, roaming is fundamental to photochemical reactions in small molecules. However, the neutral character of the roaming fragment and its indeterminate trajectory make it difficult to identify experimentally. Here, we introduce an approach to image roaming, utilizing intense, femtosecond IR radiation combined with Coulomb explosion imaging to directly reconstruct the momentum vector of the neutral roaming H 2 , a precursor to H 3 + formation, in acetonitrile, CH 3 CN. This technique provides a kinematically complete picture of the underlying molecular dynamics and yields an unambiguous experimental signature of roaming. We corroborate these findings with quantum chemistry calculations, resolving this unique dissociative process. The H 2 roaming mechanism in organic molecules is involved in the formation of H 3 + , one of the most abundant molecular ions in the universe, but its direct visualization has been challenging. Here the authors obtain direct insights into these complex dynamics by tracking the roaming H 2 molecules in acetonitrile with time-resolved Coulomb explosion imaging.
Anisotropic photoemission time delays close to a Fano resonance
Electron correlation and multielectron effects are fundamental interactions that govern many physical and chemical processes in atomic, molecular and solid state systems. The process of autoionization, induced by resonant excitation of electrons into discrete states present in the spectral continuum of atomic and molecular targets, is mediated by electron correlation. Here we investigate the attosecond photoemission dynamics in argon in the 20–40 eV spectral range, in the vicinity of the 3 s −1 np autoionizing resonances. We present measurements of the differential photoionization cross section and extract energy and angle-dependent atomic time delays with an attosecond interferometric method. With the support of a theoretical model, we are able to attribute a large part of the measured time delay anisotropy to the presence of autoionizing resonances, which not only distort the phase of the emitted photoelectron wave packet but also introduce an angular dependence. Ionization time delays are of interest in understanding the photoionization mechanism in atoms and molecules in ultra-short time scales. Here the authors investigate the angular dependence of photoionization time delays in the presence of an autoionizing resonance in argon atom using RABBITT technique.
Uncovering Ecosystem Service Bundles through Social Preferences
Ecosystem service assessments have increasingly been used to support environmental management policies, mainly based on biophysical and economic indicators. However, few studies have coped with the social-cultural dimension of ecosystem services, despite being considered a research priority. We examined how ecosystem service bundles and trade-offs emerge from diverging social preferences toward ecosystem services delivered by various types of ecosystems in Spain. We conducted 3,379 direct face-to-face questionnaires in eight different case study sites from 2007 to 2011. Overall, 90.5% of the sampled population recognized the ecosystem's capacity to deliver services. Formal studies, environmental behavior, and gender variables influenced the probability of people recognizing the ecosystem's capacity to provide services. The ecosystem services most frequently perceived by people were regulating services; of those, air purification held the greatest importance. However, statistical analysis showed that socio-cultural factors and the conservation management strategy of ecosystems (i.e., National Park, Natural Park, or a non-protected area) have an effect on social preferences toward ecosystem services. Ecosystem service trade-offs and bundles were identified by analyzing social preferences through multivariate analysis (redundancy analysis and hierarchical cluster analysis). We found a clear trade-off among provisioning services (and recreational hunting) versus regulating services and almost all cultural services. We identified three ecosystem service bundles associated with the conservation management strategy and the rural-urban gradient. We conclude that socio-cultural preferences toward ecosystem services can serve as a tool to identify relevant services for people, the factors underlying these social preferences, and emerging ecosystem service bundles and trade-offs.