One Relator Quotients of Graph Products

In this paper, we generalise Magnus' Freiheitssatz and solution to the word problem for one-relator groups by considering one relator quotients of certain classes of right-angled Artin groups and graph products of locally indicable polycyclic groups

Procesos deposicionales y antrópicos en el registro holoceno de la Cova de Can Sadurní (Begues, Barcelona, España): aportaciones microestratigráficas

El estudio geoarqueológico y microestratigráfico de la secuencia de la Cova de Can Sadurní (Begues, Barcelona) ofrece una variabilidad de procesos deposicionales de tipo detrítico y antrópico que en determinadas etapas se alternan y repercuten en los procesos diagenéticos localizados. La secuencia cultural del yacimiento va desde el Epipaleolítico hasta época Romana bajo imperial con algunas interrupciones cronoculturales. Durante el Epipaleolítico y Mesolítico los aportes solifluidales son los responsables de la sedimentación. A partir del Neolítico, movimientos de masa y procesos coluvionales son los dominantes. Se distinguen flujos densos principalmente durante el Neolítico antiguo cardial y postcardial inicial; también se localizan pero con menor extensión durante el Neolítico medio postcardial, Neolítico final/Calcolítico y en el Bronce inicial. Los aportes coluvionales no laminados aparecen en el resto de la secuencia. Estos episodios se alternan con fases de estabilidad en el medio en el que la tasa de sedimentación detrítica es menor o casi inexistente y es reemplazada por los aportes procedentes de las actividades de estabulación localizados in situ durante el Neolítico epicardial y postcardial inicial; aunque ya se constaten evidencias desde el Neolítico antiguo cardial. Asociados a estos contextos, los procesos hidromórficos se acentúan dando lugar a la formación de vivianita, fosfato de hierro, propia de lugares reductores con un gran contenido orgánico

Pilot plant for the capture of ammonia from the atmosphere of pig and poultry farms using gas-permeable membrane technology

Gas-permeable membrane (GPM) technology is a possible solution to reduce ammonia (NH3) emissions from livestock housing. This paper presents the results obtained with an NH3-capture prototype based on the use of expanded polytetrafluoroethylene (ePTFE) membranes in real conditions in a gestating sow house and a free-range laying hen house, comparing them with the results obtained in controlled laboratory conditions for the same type of waste. The NH3 present in the air of the livestock housing was captured by reaction with an acidic solution flowing inside the membranes. The periods of continuous operation of the pilot plant were 232 days at the pig farm and 256 days at the poultry farm. The NH3 recovery rate at the end of those periods was 2.3 and 0.4 g TAN·m−2·d−1 in the pig and the poultry farms, respectively. The limiting factor for the capture process was the NH3 concentration in the air, with the highest recovery occurring in the most concentrated atmosphere. Differences in NH3 capture were observed between seasons and farms, with capture efficiencies of 1.62 and 0.33 g·m−2·d−1 in summer and 3.85 and 1.20 g·m−2·d−1 in winter for pig and poultry farms, respectively. The observed differences were mainly due to the higher ventilation frequency in the summer months, which resulted in a lower NH3 concentration inside the houses compared to the winter months. This is especially important when considering the real applicability of this technology. The results obtained suggest that GPM technology holds promise for limiting NH3 emissions from livestock housing with NH3 ambient concentrations close to 20 ppm or as part of manure storage facilities, given that it allows for recovery of nitrogen in a stable and concentrated solution, which can be used as a fertilizer

Estimation of PCBs content in agricultural soils associated with long-term fertilization with organic waste

Polychlorinated biphenyl (PCB) pollution related to the use of organic waste as fertilizers in agricultural soils is a cause of major concern. In the study presented herein, PCB concentration was studied through a field trial conducted in two agricultural soils in the province of Palencia (Spain) over a 4-year period, assessing the impact of irrigation and of different types of organic waste materials. The amounts of organic waste added to the soil were calculated according to the nitrogen needs of the crop, and the concentration of PCBs was determined before and after the application of the organic waste. The resulting persistence of the total PCB content in the agricultural soils, compared with the PCB concentration in the original soils, ranged from 27% to 90%, with the lowest value corresponding to irrigated soils treated with municipal solid waste compost (MSWC) and the highest value to non-irrigated soils treated with composted sewage sludge (CSS). An estimate of the PCB content in agricultural soils after the application of organic waste materials until year 2050 was obtained, resulting in a value below 5 ng·g-1, considered a background value for soils in sites far away from potential pollution sources

Middle Neolithic farming of open-air sites in SE France: new insights from archaeobotanical investigations of three wells found at Les Bagnoles (L'Isle-sur-la-Sorgue, Dépt. Vaucluse, France)

Previous reviews of Middle Neolithic agricultural practice (4400–3500 cal bc) in southern France have highlighted a change in crop assemblages after 4000 cal bc, with a reduction of naked wheat and an increase of emmer and partly of einkorn. The recent investigation of three wells from the site of Les Bagnoles (4250–3800 cal bc) in the periphery of the southern Rhône valley yielded an unprecedented amount of waterlogged uncharred and charred plant macro remains that offer new insights into crop diversity and its changes over time. The results from the wells at Les Bagnoles were compared with other dated sunken features from open-air sites (in contrast to caves and rock shelters), with the aim of identifying patterns sug-gesting changes in the crop spectra between the early (MN1) and late (MN2) Middle Neolithic phases from taphonomically comparable contexts. The results from Les Bagnoles demonstrate that oil crops and pulses are underrepresented in dry sites and that they were a significant part of Middle Neolithic agriculture. They also indicate an increase in the representation of einkorn (instead of emmer) during MN2 that is also visible in other open-air sites. The comparison of the archaeobotani-cal results with silo storage capacity values as a proxy for average production capacity per household leads us to propose a possible drop in naked wheat productivity and opens new questions in factors affecting crop choice at the beginning of the 4th millennium cal bc

Realistic performance prediction in nanostructured solar cells as a function of nanostructure dimensionality and density

The behavior of quantum dot, quantum wire, and quantum well InAs/GaAs solar cells is studied with a very simplified model based on experimental results in order to assess their performance as a function of the low bandgap material volume fraction fLOW. The efficiency of structured devices is found to exceed the efficiency of a non-structured GaAs cell, in particular under concentration, when fLOW is high; this condition is easier to achieve with quantum wells. If three different quasi Fermi levels appear with quantum dots the efficiency can be much higher

Towards the periodization of the uses of Can Sadurní Cave (Begues, Catalonia) during the Middle Neolithic I. The contribution of bayesian modelling to radiocarbon dating sequences

Excavations at Can Sadurní Cave since 2012 have uncovered a complex stratigraphy for the Middle Neolithic phase (ca. 4700-4000 cal. BC). This was not in agreement with our expectations from the previous excavation of a trial trench, where only 4 layers (10, 10b,11 and 11b) were uncovered. After excavating a funerary layer with several in situ burials and further deposits containing multiple layers of burnt dung (fumier), the stratigraphy was revised and 5 episodes within layer 11 were detected. It became necessary to find a tool to refine the chronological sequence of these uses, under the premise that it is unlikely that the cave was used as a funerary area and a byre at the same time. Bayesian modelling allowed distinguishing these two phases, establishing an earlier use of the cave for animal herding purposes (ca. 4700-4450 cal. BC) and a funerary use of the cave in a more recent period (ca. 4400-4200 cal. BC)

Wide-bandgap InAs/InGaP quantum-dot intermediate band solar cells

Current prototypes of quantum-dot intermediate band solar cells suffer from voltage reduction due to the existence of carrier thermal escape. An enlarged sub-bandgap EL would not only minimize this problem, but would also lead to a bandgap distribution that exploits more efficiently the solar spectrum. In this work we demonstrate InAs/InGaP QD-IBSC prototypes with the following bandgap distribution: EG = 1.88 eV, EH = 1.26 eV and EL > 0.4 eV. We have measured, for the first time in this material, both the interband and intraband transitions by means of photocurrent experiments. The activation energy of the carrier thermal escape in our devices has also been measured. It is found that its value, compared to InAs/GaAs-based prototypes, does not follow the increase in EL. The benefits of using thin AlGaAs barriers before and after the quantum-dot layers are analyzed

Tratado de derechos reales. Tomo II Propiedad y posesión

La presente investigación está referida al análisis de los dos principales derechos reales: la posesión y la propiedad, y es la continuación de la investigación concluida denominada Tratado de derechos reales, tomo I, teoría de los bienes y los derechos reales. Esta parte de la investigación corresponde al desarrollo de dos de sus principales instituciones. Así, se comienza con el análisis sociojurídico de la posesión (poder hecho) como derecho transitorio (temporal y momentáneo), para luego entrar al desarrollo de la propiedad (poder de derecho) como derecho definitivo (permanente y total), ambas instituciones reconocidas como situaciones jurídicas de gran trascendencia en las relaciones jurídicas patrimoniales, protegidas por la ley a través de mecanismos de defensa

On commensurable hyperbolic Coxeter groups

For Coxeter groups acting non-cocompactly but with finite covolume on real hyperbolic space Hn, new methods are presented to distinguish them up to (wide) commensurability. We exploit these ideas and determine the commensurability classes of all hyperbolic Coxeter groups whose fundamental polyhedra are pyramids over a product of two simplices of positive dimensions