Crecimiento económico en el espacio peruano, 1681-1800: una visión a partir de la agricultura

Editada en la Fundación Empresa PúblicaEl trabajo presenta un análisis agregado y por región de la evolución de la agricultura en el espacio peruano entre 1681 y 1800, utilizando series deflactadas de diezmos. Concluye señalando que, luego de una caída inicial, existió una expansión de la agricultura durante el siglo XVIII, con una aceleración en la segunda mitad del siglo. El incremento en la producción no fue homogéneo, existiendo una destacada disparidad regional.The article presents an aggregate and regional analysis of the evolution of agriculture in the Peruvian space between 1681 and 1800, using deflated tithe series. It concludes that after an initial collapse, agricultural production expanded in the xviii century, an expansion that accelerated in the second half of the century. This increase in production was not homogeneous across regions.Publicad

Level Crossing Analysis of Burgers Equation in 1+1 Dimensions

We investigate the average frequency of positive slope $\nu_{\alpha}^{+}$, crossing the velocity field $u(x)- \bar u = \alpha$ in the Burgers equation. The level crossing analysis in the inviscid limit and total number of positive crossing of velocity field before creation of singularities are given. The main goal of this paper is to show that this quantity, $\nu_{\alpha}^{+}$, is a good measure for the fluctuations of velocity fields in the Burgers turbulence.Comment: 5 pages, 3 figure

Accelerating growth of HFC-227ea (1,1,1,2,3,3,3-heptafluoropropane) in the atmosphere

We report the first measurements of 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), a substitute for ozone depleting compounds, in air samples originating from remote regions of the atmosphere and present evidence for its accelerating growth. Observed mixing ratios ranged from below 0.01 ppt in deep firn air to 0.59 ppt in the current northern mid-latitudinal upper troposphere. Firn air samples collected in Greenland were used to reconstruct a history of atmospheric abundance. Year-on-year increases were deduced, with acceleration in the growth rate from 0.029 ppt per year in 2000 to 0.056 ppt per year in 2007. Upper tropospheric air samples provide evidence for a continuing growth until late 2009. Furthermore we calculated a stratospheric lifetime of 370 years from measurements of air samples collected on board high altitude aircraft and balloons. Emission estimates were determined from the reconstructed atmospheric trend and suggest that current "bottom-up" estimates of global emissions for 2005 are too high by a factor of three

Level Crossing Analysis of Growing surfaces

We investigate the average frequency of positive slope $\nu_{\alpha}^{+}$, crossing the height $\alpha = h- \bar h$ in the surface growing processes. The exact level crossing analysis of the random deposition model and the Kardar-Parisi-Zhang equation in the strong coupling limit before creation of singularities are given.Comment: 5 pages, two column, latex, three figure

Untying a nanoscale knotted polymer structure to linear chains for efficient gene delivery in vitro and to the brain

The purpose of this study was to develop a platform transfection technology, for applications in the brain, which could transfect astrocytes without requiring cell specific functionalization and without the common cause of toxicity through high charge density. Here we show that a simple and scalable preparation technique can be used to produce a “knot” structured cationic polymer, where single growing chains can crosslink together via disulphide intramolecular crosslinks (internal cyclizations). This well-defined knot structure can thus “untie” under reducing conditions, showing a more favorable transfection profile for astrocytes compared to 25 kDa-PEI (48-fold), SuperFect® (39-fold) and Lipofectamine®2000 (18-fold) whilst maintaining neural cell viability at over 80% after four days of culture. The high transfection/lack of toxicity of this knot structured polymer in vitro, combined with its ability to mediate luciferase transgene expression in the adult rat brain, demonstrates its use as a platform transfection technology which should be investigated further for neurodegenerative disease therapies

Synthesis of accelerograms compatible with the Chinese GB 50011-2001 design spectrum via harmonic wavelets: artificial and historic records

A versatile approach is employed to generate artificial accelerograms which satisfy the compatibility criteria prescribed by the Chinese aseismic code provisions GB 50011-2001. In particular, a frequency dependent peak factor derived by means of appropriate Monte Carlo analyses is introduced to relate the GB 50011-2001 design spectrum to a parametrically defined evolutionary power spectrum (EPS). Special attention is given to the definition of the frequency content of the EPS in order to accommodate the mathematical form of the aforementioned design spectrum. Further, a one-to-one relationship is established between the parameter controlling the time-varying intensity of the EPS and the effective strong ground motion duration. Subsequently, an efficient auto-regressive moving-average (ARMA) filtering technique is utilized to generate ensembles of non-stationary artificial accelerograms whose average response spectrum is in a close agreement with the considered design spectrum. Furthermore, a harmonic wavelet based iterative scheme is adopted to modify these artificial signals so that a close matching of the signals’ response spectra with the GB 50011-2001 design spectrum is achieved on an individual basis. This is also done for field recorded accelerograms pertaining to the May, 2008 Wenchuan seismic event. In the process, zero-phase high-pass filtering is performed to accomplish proper baseline correction of the acquired spectrum compatible artificial and field accelerograms. Numerical results are given in a tabulated format to expedite their use in practice

Improving together: better science writing through peer learning

Science, in our case the climate and geosciences, is increasingly interdisciplinary. Scientists must therefore communicate across disciplinary boundaries. For this communication to be successful, scientists must write clearly and concisely, yet the historically poor standard of scientific writing does not seem to be improving. Scientific writing must improve, and the key to long-term improvement lies with the early-career scientist (ECS). Many interventions exist for an ECS to improve their writing, like style guides and courses. However, momentum is often difficult to maintain after these interventions are completed. Continuity is key to improving writing. This paper introduces the ClimateSnack project, which aims to motivate ECSs to develop and continue to improve their writing and communication skills. The project adopts a peer-learning framework where ECSs voluntarily form writing groups at different institutes around the world. The group members learn, discuss, and improve their writing skills together. Several ClimateSnack writing groups have formed. This paper examines why some of the groups have flourished and others have dissolved. We identify the challenges involved in making a writing group successful and effective, notably the leadership of self-organized groups, and both individual and institutional time management. Within some of the groups, peer learning clearly offers a powerful tool to improve writing as well as bringing other benefits, including improved general communication skills and increased confidence

Uso del narlene para el control del nuche en el ganado vacuno

Muchas de las plaga de nuestros ganados se vienen combatiendo con bastante éxito a partir de la última década o se puede decir lo mismo con respecto al nuche, cuyos daños siguen diezmando la capacidad productiva de la población vacuna del clima medio colombiano. En efecto, las zonas cafetera que son las más densamente pobladas en Colombia, se ven privadas de los beneficios que aportan las razas mejorada y aun las criollas, por la barrera que establece este parásito para poder desarrollar una mayor y más eficiente producción en, las regiones infestada por la plaga. El consumo de leche y de carne en los climas medios de Colombia es alarmantemente bajo y trae como consecuencia una alta mortalidad infantil debida a Ha desnutrición. Muchas regiones de Colombia no producen ni más leche ni más carne porque el nuche está impidiendo la ac1imatación de ganados que podrían redimir, al menos en parte, ese vasto conglomerado de campesinos, que es la fuente principal de la riqueza colombiana. El nuche causa innumerables daños en las ganaderías de clima, medios; los alimentos no se transforman eficientemente en carne y leche, las pieles pierden mucho valor comercial, hay alta morta1idad de terneros por causas indirectas y hasta directas, las razas especializadas no prosperan y a veces llegan a ser inferiores en producción a las criollas; aún estas no pueden producir el máximo porque e1 hecho de que un animal sea resistente a una plaga no implica que su producción sea igual o mayor que cuando la p1aga no existe. La casa Dow Chemical Co. ha estado ensayando un nuevo producto, el Narlene, para controlar el nuche. Como ese nuchicida dio resultados halagadores en pruebas preliminares, se decidió hacer una serie de experimento; en fincas localizadas en climas medios con alto grado de infestación para determinar la eficacia del producto, el tiempo de protección que ofrece y la posible ganancia en peso de, los animales tratados en una de las pruebas. Se emplearon cuatro fórmulas diferentes del Narlene; algunas de ellas se usaron únicamente en uno o dos ensayos, otras se administraron en forma diferente y únicamente dos de ellas se emplearon en los 4 ensayos. Cada prueba se hizo en distintas épocas del año y en fincas diferentes por un período aproximado de un año