El siglo planetario. Periodizaciones para una historia del medio ambiente en el siglo XX

En este articulo se aborda el tema de la periodización de la historia del medio ambiente. Tras señalar la insatisfacción de las diversas propuestas que se han hecho y el difícil encaje con las divisiones convencionales utilizadas por la historiografía, el autor plantea que una de las causas principales que han dificultado establecer una cronología convincente está en que la masa de hechos que se pretende agrupar por etapas, es todavía confusos, debido a la insuficiencia de estudios teóricos y específicos que permitan establecer una per.odización. En consecuencia, el autor dedica la mayor parte del trabajo a analizar desde una triple perspectiva las transformaciones medioambientales. Examina primero los efectos de la deqradación producidos en nuestro hábitat por la presión antrópica y sobre todo por la producción Industrial, en particular los múltiples fenómenos de contarnínación del agua del suelo y de la atmósfera. Un segundo tipo de fenómenos que analiza es el cambio en el uso de recursos naturales y más exactamente en el grado y forma de incorporación en las actividades económicas. Finalmente, se centra en observar el registro cultural de estos cambios y los efectos que ha tenido en la reflexión científica, en la opinión pública y en la política con cambios legislativos y surgimiento de nuevas instituciones. El autor concluye señalando que estas tres clases de fenómenos obedecen a lógicas distintas y exigen marcos temporales diferentes y, con bastante frecuencia, existen desajustes entre ellos, aunque surge un horizonte común en la segunda mitad del siglo XX.This article deals with the periodicity in the environmental history. Since no previous divisions are satisfactory and those used by historiography are difficult to adjust within conventional divisions, the author suggests it could be mainly caused by the controversy to group events due to Ihe lack of theoretical and specific studies. The environmental transformations are analysed from a triple point of view. Firstly, the degradation effects provoked by the pressure and mainly by Ihe industrial production, particularity, water, soil, and atmosphere pollution. Secondly, changes in the use of natural resources. Finally, the cultural register of those changes and their effects on scientific though, public opinion, and policy with legislative changes and new institutions creation. The author concludes that these three points of view follow different logic demanding distinct temporal frames, and though disagreements frequently occur among them, a common perspective starts in the second half of the Twentieth century

La historia entre verdades 'discutibles' y mercado de las noticias

En un contexto cultural en el que los temas históricos se han convertido en una simple ­mercancía, Italia es además un interesante ejemplo de uso político de la Historia con una ambiciosa finalidad estratégica de dimensión europea: volver a definir la legitimidad de las grandes transformaciones de la edad contemporánea, especialmente, las que van desde la Revolución francesa, a la Revolución de Octubre, hasta el movimiento de Resistencia antifascista. En este sentido, la obra del historiador Renzo de Felice sigue siendo objeto de debate y punto de partida de una constante discusión ideológica.In a cultural context in which historical matters have become a simple merchandise, Italy is also an interesting example of political use of History with a clear and ambitious strategic purpose with an European dimension: to redefine the legitimacy of those big transformations of contemporary times, specifically those included between French Revolution, the October Revolution and the antifascist resistance movement. In this sense, the work by the historian Renzo de Felice is still object of controversy and the starting point to an intense ideological debate

Mutamenti nelle strutture della proprieta e aziende agricole in Italia

This note is intended to introduce one of the most relevant research works on the historiography of Italian agriculture, concerned with the changes in property structures and with the agrarian exploitations which have taken place in the last two centuries

Multichannel optical atomic magnetometer operating in unshielded environment

A multi-channel atomic magnetometer operating in an unshielded environment is described and characterised. The magnetometer is based on D1 optical pumping and D2 polarimetry of Cs vapour contained in gas-buffered cells. Several technical implementations are described and discussed in detail. The demonstrated sensitivity of the setup is 100fT/Hz^1/2 when operating in the difference mode.Comment: 9 pages, 5 figures, appearing in Appl.Phys.

La città. Un ecosistema di beni comuni

Le maggiori analisi storico-sociologiche che con diversi approcci, nel corso del ’900, si sono occupate di habitat e ambienti urbani, hanno tratteggiato la città come insediamento funzionale allo scambio di prodotti, centro di flussi di un mercato in progressiva espansione. L’idea che si possa considerare la città non solo come snodo di scambio di prodotti, ma come ‘frammento’ di una più ampia rete ecosistemica è una recente conquista del pensiero sociale. La cultura ambientalista e dell’ecologia urbana consente di considerare l’uomo come essere naturale, immerso nell’ambiente in cui vive e in cui riproduce le proprie attività economiche. Una necessaria ‘operazione di disvela-mento’ in cui è possibile scorgere l’universalità di beni comuni di cui la città è composta.During 1900s, main historical and sociological analysis that dealt with habitat and urban environments, from different points of view, described the city as a functional settlement for ex-change of products, centre of gradually expanding market flows. A recent achievement of social thought discusses hypothesis in which it is not possible considering the city as a hub for the ex-change of products, but as a ‘fragment’ of a wider ecosystem network. The urban ecology and envi-ronmentalist culture allows considering man as a natural being, embedded in the environment in which lives and reproduces his economic activities. A necessary ‘operation of revelation’ in which it is possible to see the universality of the commons that compose the city

Una nuova agricoltura per le aree interne

Depositarie di saperi ed economie, colture e culture perfezionatesi nella storia ‘lunga’ della coevoluzione di comunità e ambienti di vita, le ‘aree interne’ del nostro Paese (i territori degli entroterra collinari, pedemontani e montani che dominano - non solo percentualmente - il paesaggio italiano) si candidano a diventare, da sacche residuali e degradate dello ‘sviluppo’ capitalistico, laboratori operanti di una nuova agricoltura, percepita e praticata come produzione multifunzionale di servizi sistemici e in nessun modo riducibile alle pure leggi dell’economia; ma che anzi, nei nuovi circuiti di produzione di valore e nella molteplicità di pratiche autenticamente autosostenibili cui dà vita, dischiude nuove opportunità per la riforma ecologica di quella economia e della società che la pratica.Owners of knowledge and economies, cultures and agricultures improved in the ‘long’ co-evolution history of communities and living environments, the ‘inner areas’ of our country (territories of the inland hills, foothills and mountains which - not only in percentage - dominate the Italian landscape) apply for becoming, from residual and decayed pockets of the capitalist ‘development’, proactive laboratories for a new agriculture, perceived and practiced as a multifunctional production of systemic services and in no way reducible to the pure laws of economics; but which rather, in the new value circuits and in the multiplicity of genuine self-sustainable practices it creates, opens up new opportunities for an ecological reform of that economy and its society

Energy Recovery from the LNG Regasification Process

The global request of natural gas (NG) is continuously increasing, consequently also the regasification of liquefied natural gas (LNG) is becoming a process largely employed. Liquefied natural gas at a temperature of around 113 K at atmospheric pressure has to be regasified for its transportation by pipeline. The regasification process makes the LNG exergy available for various applications, particularly for the production of electrical energy. Different possibilities to exploit the thermal energy released during regasification are available. New plant configurations whose functioning does not constrain the processes of the regasification terminal are proposed. A possible solution is LNG exploitation as a cold source for ocean thermal energy conversion (OTEC) power plants. Electric energy can be produced also by the exploitation of heat released from hot sources, for instance, the condensation heat of power plants by means of consecutive thermodynamic cycles. The rational use of the cold source (LNG) allows the increment of electrical production and growth of the thermodynamic efficiency, with corresponding environmental benefits

A Second Law Analysis to Determine the Environmental Impact of Boilers Supplied by Different Fuels

A novel procedure to determine the environmental quality of boilers based on the combustion entropy degradation, the pollutants emission and the device efficiency is proposed. The entropy generation due to the chemical reaction was determined and then the irreversibilities on the external environment were first quantified. Successively, the entropy generation numbers of the combustion reactions were combined with the heat transfer process entropy generation of the boilers to consider the actual functioning conditions, in order to quantify the environmental damages by introducing an Environment Quality Index (EQI). A parametric study varying the heat exchanger efficiency, fluid flow rates and temperatures, for different fuel typologies, was performed to assess the environmental impact. Solar hydrogen was considered for its importance as future renewable energy carrier. The results showed that the highest EQI was produced by the natural gas, but if heat exchanger parameters are defined opportunely, the score gap with other fluids can be recovered. For hydrogen and coal decreasing the flue gases temperature or by increasing the flue gases mass flow rate can strongly improve the EQI index, whereas the gap recovery for Diesel is rather difficult

Fast, cheap, and scalable magnetic tracker with an array of magnetoresistors

We present the hardware of a cheap multi-sensor magnetometric setup where a relatively large set of magnetic field components is measured in several positions by calibrated magnetoresistive detectors. The setup is developed with the scope of mapping the (inhomogeneous) field generated by a known magnetic source, which is measured as superimposed to the (homogeneous) geomagnetic field. The final goal is to use the data produced by this hardware to reconstruct position and orientation of the magnetic source with respect to the sensor frame, simultaneously with the orientation of the frame with respect to the environmental field. Possible applications of the setup are shortly discussed, together with a synthetic description of the data elaboration and analysis.Comment: 10 pages, 7 figures, 30 ref