113 research outputs found
The method of instructing children rationally in the arts of writing and reading. By J. Neef.
No full text338 p
Manfred Max Neef y la revolución ambientalista para América Latina, 1932-2019 (in memoriam)
No full textWith the article, it is offered a tribute to the work of Manfred Max Neef, Chilean intellectual,
politician, ecologist and economist, Alternative Nobel Prize winner in Economics, a pioneer in ecological
criticism of both productivism and extractivism in Latin America. The methodology used in this work
is based on the review of the main books published by the author, such as Barefoot Economy (1982),
Development on a Human Scale (1986), The Lost Dimension (2007), and The Unmasked Economy
(2014). It is held as an assumption that Max Neef’s work fits into a Latin American theoretical body,
which breaks intellectually with macroeconomic models, be they developmentalist or neoliberal in
nature. The originality of his contribution is in the defense of the ecological foundations for human
development at a local scale.Con el artículo, se ofrece un homenaje a la obra de Manfred Max Neef, intelectual, político, eco-
logista y economista chileno, Premio Nobel Alternativo en Economía, pionero en la crítica ecológica,
tanto en el productivismo como en el extractivismo en América Latina. La metodología empleada
en este trabajo se funda en la revisión de los principales libros publicados por el autor, tales como
Economía descalza (1982), Desarrollo a escala humana (1986), La dimensión perdida (2007) y La
economía desenmascarada (2014). Se sostiene como supuesto que la obra de Max Neef se encuadra
en un cuerpo teórico latinoamericano, que rompe intelectualmente con los modelos macroeconómi-
cos, sean de corte desarrollista o de tipo neoliberal. La originalidad de su aporte se encuentra en la
defensa de los fundamentos ecológicos para el desarrollo humano a una escala local
Author response: The synaptic ribbon is critical for sound encoding at high rates and with temporal precision
No full textWe studied the role of the synaptic ribbon for sound encoding at the synapses between inner hair cells (IHCs) and spiral ganglion neurons (SGNs) in mice lacking RIBEYE (RBEKO/KO). Electron and immunofluorescence microscopy revealed a lack of synaptic ribbons and an assembly of several small active zones (AZs) at each synaptic contact. Spontaneous and sound-evoked firing rates of SGNs and their compound action potential were reduced, indicating impaired transmission at ribbonless IHC-SGN synapses. The temporal precision of sound encoding was impaired and the recovery of SGN-firing from adaptation indicated slowed synaptic vesicle (SV) replenishment. Activation of Ca2+-channels was shifted to more depolarized potentials and exocytosis was reduced for weak depolarizations. Presynaptic Ca2+-signals showed a broader spread, compatible with the altered Ca2+-channel clustering observed by super-resolution immunofluorescence microscopy. We postulate that RIBEYE disruption is partially compensated by multi-AZ organization. The remaining synaptic deficit indicates ribbon function in SV-replenishment and Ca2+-channel regulation
Author response: Gender bias in scholarly peer review
No full textPeer review is the cornerstone of scholarly publishing and it is essential that peer reviewers are appointed on the basis of their expertise alone. However, it is difficult to check for any bias in the peer-review process because the identity of peer reviewers generally remains confidential. Here, using public information about the identities of 9000 editors and 43000 reviewers from the Frontiers series of journals, we show that women are underrepresented in the peer-review process, that editors of both genders operate with substantial same-gender preference (homophily), and that the mechanisms of this homophily are gender-dependent. We also show that homophily will persist even if numerical parity between genders is reached, highlighting the need for increased efforts to combat subtler forms of gender bias in scholarly publishing
Balance dynamics and gravity waves in four-dimensional data assimilation
No full textThis thesis examines the application of three methods of so-called four-dimensional data assimilation to dynamical models where there exists a timescale separation between vortical motion and (relatively fast) inertia-gravity waves. Using a highly simplified dynamical model which admits one nonlinear vortical mode and one inertia-gravity wave, we evaluate the relative strengths and weaknesses of linearization-based and ensemble-based sequential assimilation (i.e. two varieties of the Kalman filter), and four-dimensional variational assimilation (4DVAR). The first part of this study is concerned with balanced flow, or flow where vortical motion dominates and inertial/gravitational motion is "slaved" to the dominant flow. The goal of assimilation in this context is to recover the true balanced state, without the excitation of spurious inertia-gravity waves. It is shown that the excitation of spurious waves becomes more difficult to control as the nonlinearity of the assimilation system is increased, for example by decreasing observation frequency. If not enough components of the true state are observed or observations are infrequent relative to the nonlinearity of the model, the explicit evolution of error covariances using a tangent-linear model can easily become quite inaccurate, which results in a highly unstable assimilation cycle wherein spurious waves are excited and not controlled. Both ensemble-based and implicit variational covariance models offer improvements, but these are themselves limited by error due to sampling and non-Gaussianity of the ensemble and by the tendency to settle into local minima of a non-quadratic cost function. The analysis is then extended to dynamical regimes where the inertia-gravity wave becomes more important to the evolution of the system as a whole, either by increasing its magnitude, decreasing the timescale separation, or increasing the coupling between fast and slow modes. It is found that recovery of either mode from observations that contain both timescales benefits from the four-dimensional estimation of error statistics. The ability to extract both modes from observations which contain both timescales of motion depends both on the estimated fast-slow covariances, as well as the estimated error variance ascribed to the gravity wave. Recovery of a non-negligible inertia-gravity wave is found to be possible with the Kalman filter, and more so if an ensemble is used to estimate covariances, but extremely difficult for variational assimilation. It is also found that accuracy of the assimilation for the different regimes of balance/imbalance can be weakened considerably as systematic model error is added and increased. Some typical modifications designed to counter systematic error are shown to alleviate some of these problems, but also increase the excitation of spurious imbalance.Ph.D
Modelling Capillary Effects in Heterogeneous Porous Media
No full textElectrical Engineering, Mathematics and Computer Scienc
Comparison of Earth rotation excitation in data-constrained and unconstrained atmosphere models
No full textChanges in Earth rotation are strongly related to fluctuations in the angular momentum of the atmosphere, and therefore contain integral information about the atmospheric state. Here we investigate the extent to which observed Earth rotation parameters can be used to evaluate and potentially constrain atmospheric models. This is done by comparing the atmospheric excitation function, computed geophysically from reanalysis data and climate model simulations constrained only by boundary forcings, to the excitation functions inferred from geodetic monitoring data. Model differences are assessed for subseasonal variations, the annual and semiannual cycles, interannual variations, and decadal-scale variations. Observed length-of-day anomalies on the subseasonal timescale are simulated well by the simulations that are constrained by meteorological data only, whereas the annual cycle in length-of-day is simulated well by all models. Interannual length-of-day variations are captured fairly well as long as a model has realistic, time-varying SST boundary conditions and QBO forcing. Observations of polar motion are most clearly relatable to atmospheric dynamics on subseasonal to annual timescales, though angular momentum budget closure is difficult to achieve even for data-constrained atmospheric simulations. Closure of the angular momentum budget on decadal timescales is difficult and strongly dependent on estimates of angular momentum fluctuations due to core-mantle interactions in the solid Earth.
Key Points:
Earth rotation parameters contain global information about atmospheric dynamics;
Length-of-day observations can constrain modeled winds in tropical regions;
Polar motion observations can constrain modeled mass movements in midlatitude
The Earth Rotation Signature of Sudden Stratospheric Warmings
No full text<p>The top 2 panels show anomalies in polar cap temperature (a) and zonal mean zonal wind (b) composited over all sudden stratospheric warmings between 1963 and 2010 and centered on the where the 10hPa wind reverses for each warming event. We see the classic downward-propagating "signature" of SSWs. The bottom three panels show the observed polar motion angles and length-of-day anomalies, composited the same way. We can see a pretty clear impact of SSWs in Polar Motion angle 2 and length-of-day, though only the polar motion signal is statistically significant.</p
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