1,953 research outputs found
Changes in organic matter, nitrogen, phosphorus and cations in soil as a result of fire and water erosion in a Mediterranean landscape
10 páginas, 7 figuras, 9 tablas.Fire affects large parts of the dry Mediterranean shrubland, resulting in erosion and losses of plant nutrients. We have attempted to measure these effects experimentally on a calcareous hillside representative of such shrubland. Experimental fires were made on plots (4 m x 20 m) in which the fuel was controlled to obtain two different fire intensities giving means of soil surface temperature of 439 degrees C and 232 degrees C with temperatures exceeding 100 degrees C lasting for 36 min and 17 min. The immediate and subsequent changes induced by fire on the soil's organic matter content and other soil chemical properties were evaluated, together with the impact of water erosion.
Seven erosive rain events, which occurred after the experimental fires (from August 1995 to December 1996), were selected, and on them runoff and sediment produced from each plot were measured. The sediments collected were weighed and analysed. Taking into account the variations induced by fire on the soil properties and their losses by water erosion, estimates of the net inputs and outputs of the soil system were made. Results show that the greatest losses of both soil and nutrients took place in the 4 months immediately after the fire. Plots affected by the most intense fire showed greater losses of soil (4077 kg ha(-1)) than those with moderate fire intensity (3280 kg ha(-1)). The unburned plots produced the least sediment (72.8 kg ha(-1)). Organic matter and nutrient losses by water erosion were related to the degree of fire intensity. However, the largest losses of N-NH4+ and N-NO3- by water erosion corresponded to the moderate fire (8.1 and 7.5 mg N m(-2), respectively).Peer reviewe
A Modular Mobile Robotic Platform to Assist People with Different Degrees of Disability
Robotics to support elderly people in living independently and to assist disabled people in carrying out the activities of daily living independently have demonstrated good results. Basically, there are two approaches: one of them is based on mobile robot assistants, such as Care-O-bot, PR2, and Tiago, among others; the other one is the use of an external robotic arm or a robotic exoskeleton fixed or mounted on a wheelchair. In this paper, a modular mobile robotic platform to assist moderately and severely impaired people based on an upper limb robotic exoskeleton mounted on a robotized wheel chair is presented. This mobile robotic platform can be customized for each user’s needs by exploiting its modularity. Finally, experimental results in a simulated home environment with a living room and a kitchen area, in order to simulate the interaction of the user with different elements of a home, are presented. In this experiment, a subject suffering from multiple sclerosis performed different activities of daily living (ADLs) using the platform in front of a group of clinicians composed of nurses, doctors, and occupational therapists. After that, the subject and the clinicians replied to a usability questionnaire. The results were quite good, but two key factors arose that need to be improved: the complexity and the cumbersome aspect of the platform.This work was supported by the AIDE project through Grant Agreement No. 645322 of the European Commission, by the Conselleria d’Educacio, Cultura i Esport of Generalitat Valenciana, by the European Social Fund—Investing in your future, through the grant ACIF 2018/214, and by the PromociĂłn de empleo joven e implantaciĂłn de garantĂa juvenil en I+D+I 2018 through the grant PEJ2018-002670-A
Influence of air velocity and temperature on ultrasonically assisted low temperature drying of eggplant
[EN] The aim of this work was to evaluate the feasibility of power ultrasound (US) application
during the low temperature drying (LTD) of eggplant, analyzing the influence of the process
variables linked to the air flow (velocity and temperature) on the drying kinetics and
different quality aspects of the dehydrated product. For that purpose, eggplant (Solanum
melongena var. Black Enorma) cubes (8.6 mm side) were dried at different air velocities (1, 2,
4 and 6 m/s) and temperatures (10, 0 and
−10 ◦C) without (AIR) and with (AIR + US) US application.
The rise in the air velocity and temperature led to an increase in the drying rate in
AIR experiments. US application accelerated the drying process under every experimental
condition tested, shortening the drying time by up to 87%. As for the quality parameters, no
remarkable influence of the process variables (US application, air velocity and temperature)
on the rehydration, reconstitution in olive oil or hardness of the rehydrated product was
observed.The authors acknowledge the financial support of the Spanish Ministerio de Economia y Competitividad (MINECO) and the European Regional Development Fund (ERDF) through project DPI2012-37466-CO3-03 and the FPI fellowship (BES-2010-033460) granted to J.V. Santacatalina and the Generalitat Valenciana through the project PROMETE0II/2014/005.Santacatalina, JV.; Soriano, J.; Cárcel CarriĂłn, JA.; GarcĂa PĂ©rez, JV. (2016). Influence of air velocity and temperature on ultrasonically assisted low temperature drying of eggplant. Food and Bioproducts Processing. 100:282-291. https://doi.org/10.1016/j.fbp.2016.07.010S28229110
Aggregation of under canopy and bare soils in a Mediterranean environment affected by different fire intensities
7 páginas, 4 figuras, 3 tablas.Soil macroaggregation in relation to soil organic matter (SOM) and calcium carbonate(CaCO3) content was studied, before and after experimental fires of different intensities, in two environments (under canopy and on bare soil). In 1995, two experimental fire treatments, based on the addition of different biomass amounts, were applied on a set of nine plots at the Permanent Field Station of La Concordia (Valencia, Spain). Three plots were burned with high intensity fire (T1), three with moderate intensity (T2) and three plots were left unburned to be used as control treatment (T3).
Soils under canopy were characterized by higher macroaggregate stability (SMS), SOM content and mean weight diameter of aggregates (MWD) than bare soils, which presented higher CaCO3 contents. After the fires, tendencies to increase were observed in the SOM and SMS of all burned soils, probably because of the incorporation of partially burned plant material. The trends of SMS and SOM in T1 burned soils were towards to decrease with the occurrence of the first erosive rainfalls. These trends continued until the end of the study. MWD of under canopy soils on T1 and of soils on T2 showed a decreasing trend immediately after fire treatments. Not significant differences between sampling periods were found for CaCO3 content, with the exception of under canopy soils on T1 which tended to increase, and showed higher values at the end of the studied period. The differences observed initially between under canopy and bare soil disappeared after one year of fire in T1, which suggests a major degradation of soils affected by this treatment. Significant changes of the studied properties were not observed in unburned soils during one year of research. In these soils, organic matter showed significant correlations with macroaggregate stability and mean weight diameter. However, significant statistical relationships were not observed between the Studied properties in burned soils, showing that fire impact probably affected other soil characteristics related to soil aggregation.We thank the financial support from the Agreement Generalitat Valenciana — CSIC (2005020112) “Impacto de los incendios forestalesrepetidos sobre los procesos de erosiĂłn hĂdrica del suelo y la recuperaciĂłn
de la cubierta vegetal. Seguimiento y evaluación en una estación permanente de campo”, and the Ministerio de Educación y
Ciencia of the Spanish Government project “Procesos y balances hidrológicos
y de sedimentos a diferentes escalas espaciales en ambientes mediterráneos: Efectos de la variabilidad climática y los cambios de uso del suelo” (PROBASE CGL2006-11619).Peer reviewe
Hydrological properties of a Mediterranean soil burned with different fire intensities
8 páginas, 5 figuras, 3 tablas.The influence of vegetation cover on soil hydrological properties and its response to the impact of different fire intensities, in a Mediterranean forest environment, has been evaluated. The study was carried out in the Permanent Experimental Field Station of La Concordia (Lliria-Valencia, Spain), on a set of nine erosion plots (4 x 20 m(2)). The Station is located on a calcareous hillside S-SE oriented, with soils of Rendzic Leptosol type and supporting Mediterranean shrubland vegetation. All runoff generated and sediment produced in every rain event was collected from each plot. The set up includes a system of sensors for the continuous monitoring of climatic parameters (air temperature and humidity, rain volume, intensity, etc.).
In June 1995, a set of experimental fires was carried out to the Station. Three of the plots were burned with high intensity fire, three with moderate intensity and the remaining were left unaltered. Soil water content and water retention capacity (WRC) were measured in the different plots and in two different vegetation covers: under canopy (UC) and in bare soil (BS). The pF curves were also obtained for each fire treatment.
A year after the fires (June 1995-June 1996), great differences, reaching 77.15%, in runoff generation between fire treatments and the control plots were observed.
No significant differences were detected on water retention capacity between soils UC and BS in the burned plots. However, these differences appeared in the control plots, giving UC and BS values of 13% and 18%, respectively. Plots corresponding to the high intensity fire treatment showed values of WRC significantly higher than those of the moderate intensity and of the control treatments.
The pF curves show that the values of water volume, at the different pressure points studied, were slightly greater on UC soil. Values obtained for BS samples are higher in the fire treatments, showing significant differences in respect to the control plots at pF 1 and 2. These differences were also observed for UC soil, but in this case at pF 2, 2.5 and 4.2.This work has been supported by the European Union (QLRT-2000-00289), the Spanish Ministry of Science and Technology (CICYT) REN2001-1716 and Convenio (Agreement) Generalitat Valenciana – CSIC (02020024).Peer reviewe
Tele-Rehabilitation Versus Local Rehabilitation Therapies Assisted by Robotic Devices: A Pilot Study with Patients
The present study aims to evaluate the advantages of a master-slave robotic rehabilitation therapy in which the patient is assisted in real-time by a therapist. We have also explored if this type of strategy is applicable in a tele-rehabilitation environment. A pilot study has been carried out involving 10 patients who have performed a point-to-point rehabilitation exercise supported by three assistance modalities: fixed assistance (without therapist interaction), local therapist assistance, and remote therapist assistance in a simulated tele-rehabiliation scenario. The rehabilitation exercise will be performed using an upper-limb rehabilitation robotic device that assists the patients through force fields. The results suggest that the assistance provided by the therapist is better adapted to patient needs than fixed assistance mode. Therefore, it maximizes the patient’s level of effort, which is an important aspect to improve the rehabilitation outcomes. We have also seen that in a tele-rehabilitation environment it is more difficult to assess when to assist the patient than locally. However, the assistance suits patients better than the fixed assistance mode.This work was funded by the Conselleria d’Educacio, Cultura i Esport of Generalitat Valenciana by the European Social Fund—Investing in your Future, through the grant ACIF 2018/214, PEJ2018-002684-A and PEJ2018-002670-A, and by the Spanish Ministry of Science and Innovation through the project PID2019-108310RB-I00
Estudio mecánico sobre la resistencia de la pared de la aorta humana como predictor de riesgo de rotura de aneurisma
Definir el riesgo de rotura de un aneurisma, se considera un factor básico para elegir el momento adecuado de la intervenciĂłn quirĂşrgica. Uno de los parámetros clásico utilizados es el diámetro del aneurisma (Ley de la Place). Sin embargo, otro factor mecánico como es el cociente entre la tensiĂłn máxima que soporta la pared (depende del diámetro de la aorta y de la morfologĂa) y de la resistencia del material (pared de la aorta) es un elemento poco conocido. La razĂłn estriba en comparar aortas “sanas” con “patolĂłgicas”. Este estudio lo hemos realizado en colaboraciĂłn con el Departamento de Ciencias de Materiales de la Universidad PolitĂ©cnica de Madri
Impact of power ultrasound on the quality of fruits and vegetables during dehydration
Trabajo presentado en el 2015 International Congress on Ultrasonics, celebrado los dĂas 10 a 14 de mayo de 2015 en Metz, FranciaTo date, most of dehydrated vegetables and fruits are obtained
by convection preceded or not by a pre-treatment.
In general, their quality is low due to the physical modi-
fications, loss of vitamins, polyphenols and carbohydrates
and Maillard reaction (MR). MR can originate a remarkable
loss of nutritional value due to the involvement of
lysine. To improve the final quality of these products, one
of the alternatives is the application of power ultrasound
(US). US produces mechanical effects, such as cavitation,
microstream and formation of microscopic channels which
facilitate the mass transport and so, the removal of water
from the food. The synergistic effect of US and temperature
allows carrying out dehydration at low temperatures
and short times. In the present work, the influence of
power US on the quality of fruits and vegetables during
the pre-treatment and drying was evaluated. Chemical
indicators such as pectinmethyl esterase and peroxidase
enzymes, vitamin C, carbohydrates, proteins, polyphenols
and 2-furoylmethylamino acids was studied. In addition,
rehydration capacity, leaching losses, shrinkage and
organoleptic characteristics of the final product was assessed.
During blanching, similar leaching losses and enzyme
inactivation were found in low temperature and prolonged
conventional treatments and in US processes, but
with a significant reduction in the time for the latter. Application
of US in the drying of carrots and strawberries
provided high-quality end-products. The quality was better
as compared to marketed products and superior or
equivalent to samples obtained in a convective dryer, and,
in some indicators, similar to that of freeze-dried samples.Peer reviewe
Stabilized vortex solitons in layered Kerr media
In this letter we demonstrate the possibility of stabilizing beams with
angular momentum propagating in Kerr media. Large propagation distances without
filamentation can be achieved in layered media with alternating focusing and
defocusing nonlinearities. Stronger stabilization can be obtained with the
addition of an incoherent beam.Comment: 4 pages, 3 figures. We have removed the sentence "Thus, they
erroneously point out to the existence of fully stabilized vortex solitons"
in page 2, column 2, line 7-8, because it might be confusin
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