329 research outputs found

    Service level agreement framework for differentiated survivability in GMPLS-based IP-over-optical networks

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    In the next generation optical internet, GMPLS based IP-over-optical networks, ISPs will be required to support a wide variety of applications each having their own requirements. These requirements are contracted by means of the SLA. This paper describes a recovery framework that may be included in the SLA contract between ISP and customers in order to provide the required level of survivability. A key concern with such a recovery framework is how to present the different survivability alternatives including recovery techniques, failure scenario and layered integration into a transparent manner for customers. In this paper, two issues are investigated. First, the performance of the recovery framework when applying a proposed mapping procedure as an admission control mechanism in the edge router considering a smart-edge simple-core GMPLS-based IP/WDM network is considered. The second issue pertains to the performance of a pre-allocated restoration and its ability to provide protected connections under different failure scenarios

    The Magnetic Topology of Coronal Mass Ejection sources

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    In an attempt to test current initiation models of coronal mass ejections (CMEs), with an emphasis on the magnetic breakout model, we inspect the magnetic topology of the sources of 26 CME events in the context of their chromospheric and coronal response in an interval of approximately nine hours around the eruption onset. First, we perform current-free (potential) extrapolations of photospheric magnetograms to retrieve the key topological ingredients, such as coronal magnetic null points. Then we compare the reconnection signatures observed in the high cadence and high spatial resolution of the Transition Region And Coronal Explorer (TRACE) images with the location of the relevant topological features. The comparison reveals that only seven events can be interpreted in terms of the breakout model, which requires a multi-polar topology with pre-eruption reconnection at a coronal null. We find, however, that a larger number of events (twelve) can not be interpreted in those terms. No magnetic null is found in six of them. Seven other cases remain difficult to interpret. We also show that there are no systematic differences between the CME speed and flare energies of events under different interpretations.Comment: Accepted for publication in Ap

    Emission heights of coronal bright points on Fe XII radiance map

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    We study the emission heights of the coronal bright points (BPs) above the photosphere in the bipolar magnetic loops that are apparently associated with them. As BPs are seen in projection against the disk their true emission heights are unknown. The correlation of the BP locations on the Fe XII radiance map from EIT with the magnetic field features (in particular neutral lines) was investigated in detail. The coronal magnetic field was determined by an extrapolation of the photospheric field to different altitudes above the disk. It was found that most BPs sit on or near a photospheric neutral line, but that the emission occurs at a height of about 5 Mm. Some BPs, while being seen in projection, still seem to coincide with neutral lines, although their emission takes place at heights of more than 10 Mm. Such coincidences almost disappear for emissions above 20 Mm. We also projected the upper segments of the 3-D magnetic field lines above different heights, respectively, on to the x-y plane. The shape of each BP was compared with the respective field-line segment nearby. This comparison suggests that most coronal BPs are actually located on the top of their associated magnetic loops. Finally, we calculated for each selected BP region the correlation coefficient between the Fe XII intensity enhancement and the horizontal component of the extrapolated magnetic field vector at the same x-y position in planes of different heights, respectively. We found that for almost all the BP regions we studied the correlation coefficient, with increasing height, increases to a maximal value and then decreases again. The height corresponding to this maximum was defined as the correlation height, which for most bright points was found to range below 20 Mm.Comment: 7 pages, 4 figures, 1 tabl

    Velocity measurements for a solar active region fan loop from Hinode/EIS observations

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    The velocity pattern of a fan loop structure within a solar active region over the temperature range 0.15-1.5 MK is derived using data from the EUV Imaging Spectrometer (EIS) on board the Hinode satellite. The loop is aligned towards the observer's line-of-sight and shows downflows (redshifts) of around 15 km/s up to a temperature of 0.8 MK, but for temperatures of 1.0 MK and above the measured velocity shifts are consistent with no net flow. This velocity result applies over a projected spatial distance of 9 Mm and demonstrates that the cooler, redshifted plasma is physically disconnected from the hotter, stationary plasma. A scenario in which the fan loops consist of at least two groups of "strands" - one cooler and downflowing, the other hotter and stationary -- is suggested. The cooler strands may represent a later evolutionary stage of the hotter strands. A density diagnostic of Mg VII was used to show that the electron density at around 0.8 MK falls from 3.2 x 10^9 cm^-3 at the loop base, to 5.0 x 10^8 cm^-3 at a projected height of 15 Mm. A filling factor of 0.2 is found at temperatures close to the formation temperature of Mg VII (0.8 MK), confirming that the cooler, downflowing plasma occupies only a fraction of the apparent loop volume. The fan loop is rooted within a so-called "outflow region" that displays low intensity and blueshifts of up to 25 km/s in Fe XII 195.12 A (formed at 1.5 MK), in contrast to the loop's redshifts of 15 km/s at 0.8 MK. A new technique for obtaining an absolute wavelength calibration for the EIS instrument is presented and an instrumental effect, possibly related to a distorted point spread function, that affects velocity measurements is identified.Comment: 42 pages, 15 figures, submitted to Ap

    Posidonia oceanica (L.) Delile in its westernmost biogeographical limit (northwestern Alboran Sea): Meadows characterisation, phenology and flowering events

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    Posidonia oceanica is a Mediterranean endemic seagrass species that forms meadows covering ca. 2.5–4.5 millions of hectares, representing ca.25 % of the infralittoral and shallow circalittoral (down to 50m) bottoms of the Mediterranean. This seagrass is considered a habitat-engineer species and provides an elevated number of ecosystem services. In addition the Marine Strategy Framework Directive (MSFD, 2008/56/EC) includes seagrass like elements to evaluate the “Good Environmental Status” of the European coasts. Information about their phenological characteristic and structure of the meadows is needed for indicator estimations in order to establish their conservation status. The studied meadows are located in the westernmost limit of the P. oceanica distribution (North-western Alboran Sea) in the vecinity of the Strait of Gibraltar, an Atlantic-Mediterranean water transition area. Four sites were selected from East to West: Paraje Natural de Acantilados de Maro-Cerro Gordo (hereafter Maro), Special Area of Conservation “Calahonda” (hereafter Calahonda), Site of Community Importance Estepona (hereafter Estepona) and Punta Chullera (hereafter Chullera) where P. oceanica present their westernmost meadows. Phenological data were recorded from mid November to mid December in P. oceanica patches located at 2 – 3 m depth. At each site three types of patches (patch area 2 m2, large patches) were sampled. At each patch and site, 3 quadrants of 45 x 45 cm were sampled for shoot and inflorescences density measurements. In each quadrant, 10 random shoots were sampled for shoot morphology (shoot height and number of leaves). Shoot and inflorescences densities were standardized to squared meters. All the studied P. oceanica meadows develop on rocks and they present a fragmented structure with a coverage ranging between ca. 45% in Calahonda and Estepona and ca. 31% in Maro. The meadows of Chullera are reduced to a few small - medium patches with areas ranging between 0.5-1.5 m2 (Fig. 1). The meadows of Chullera and Estepona presented similar values of shoot density (ca. 752 – 662 shoots m-2, respectively) and leaf height (ca. 25 cm). Similarly, the Calahonda and Maro meadows also showed similar values of shoot density (ca. 510 – 550 shoots m-2, respectively) but displaying lower values than those of sites located closer to the Strait of Gibraltar. Regarding patch sizes and leaf height, the longest leaves (ca. 25 cm) were found in medium and large patches, but the number of leaves per shoot were higher in the small and the medium size patches (ca. 6.3 leaves per shoot). Flowering was only detected at the Calahonda meadows with maximum values of ca. 330 inflorescences m-2 (115.2 ± 98.2 inflorescences m-2, n= 9; mean ± SD) (Fig.1). Inflorescence density was not significant different among patches of different sizes. In the Alboran Sea and unlike the studied meadows, extensive beds of P. oceanica occur at the National Park of Cabo de Gata (northeastern Alboran Sea), but from east to west (Strait of Gibraltar), meadows are gradually fragmenting and their depth range decrease from 30m to 2m depth between Cabo de Gata and Chullera, respectively. Probably, the Atlantic influence and the characteristic oceanographic conditions of the Alboran Sea (i.e., higher turbidity, higher water turbulence) represent a developmental limiting factor for P. oceanica at higher depths. Similarities between the meadows located closer to Strait of Gibraltar (Chullera and Estepona) were detected as well as between those more distant (Calahonda and Maro). The first ones showed higher values of shoot densities and leaf heights than the formers, which could be relating to the higher hydrodynamic exposure found at Chullera and Estepona meadows. Regarding flowering events, sexual reproduction in P. oceanica is not common in different locations of the Mediterranean Sea. The available information seems to indicate that flowering represent an irregular event and it is related to high seawater temperature. In fact, the flowering episodes that occurred in Calahonda in November 2015, match with the warmest year ever recorded. This is the third flowering event registered in these meadows located close to the westernmost distributional limit of P. oceanica (Málaga, Alboran Sea), which could indicates that these meadows presents a healthy status. Furthermore, the absence of significant differences in relation to inflorescence density between patches of different sizes may be indicating that the fragmentation does not necessarily influence on the flowering of this seagrass species

    Estabilidad de patatas chips fritas en aceites vegetales de distinto grado de insaturación. Efecto del palmitato de ascorbilo durante el almacenamiento

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    Four vegetable oils with different polyunsaturated/saturated fatty acid ratio (P/S): 5.2 for sunflower oil, 3.,4 for canola rapeseed oil, 0.4 for a blend of palm oleic and canola rapeseed oil (80:20), and 0.3 for palm olein were assayed for stability of crisps fried in these oils during storage at 60º C. The action of ascorbyl palmitate with special attention to its synergistic effect on the natural antioxidants was also tested. by addition to the fried potatoes. The evolution of the oxidative stability was measured through peroxide value, quantitation of tocopherols and tocotrienols, and induction time (IT) by means of Rancimat. Oil degradation during frying was very low as both polar compound percentages and natural antioxidant had similar levels to those present in refined oils. Evolution of analytical parameters during storage results indicated that oil unsaturation degree or P/S had a much more importance on stability of the product than had the content and type of natural antioxidants and the addition of AP. Nevertheless, addition of AP to the fried potatoes had a significant effect resulting in higher retention of natural antioxidants, higher IT and lower PV at any storage timeSe estudia la evolución de la oxidación a 60º C en patatas fritas con cuatro aceites vegetales de distinta relación ácidos grasos poliinsaturados/saturados (P/S): 5,4 para el aceite de girasol, 3,4 para el aceite de canola, 0,4 para una mezcla de oleína de palma (80 %) y aceite de canola (20 %) y 0,3 para la oleína de palma. Se estudia igualmente la influencia de la adición de palmitato de ascorbilo (AP) durante la conservación del producto frito con especial atención a su efecto sinergista sobre los antioxidantes naturales. La evolución de la oxidación en lotes de patatas, con y sin adición de AP, se determinó mediante las siguientes determinaciones analíticas: índice de peróxidos (PV), cuantificación de tocoferoles y tocotrienoles, y periodos de inducción (IT) en Rancimat. La degradación de los aceites durante el proceso de fritura fue muy baja puesto que los niveles de compuestos polares y de antioxidantes naturales fueron similares a los encontrados en aceites refinados. La evolución de los índices analíticos durante el almacenamiento mostraron la importancia primordial del grado de insaturación del aceite por encima de la cantidad y tipo de antioxidantes y de la adición de AP. Sin embargo, la adición de AP a las patatas fritas tuvo un claro efecto sinergista traducido en menores PV y mayores cantidades de antioxidantes naturales e IT para cualquier tiempo de almacenamiento

    Trastornos del desarrollo en niños y adolescentes de la región de Los Ríos, Valdivia, Chile, 2006-2008

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    ResumenObjetivoEstudiar los posibles hallazgos de factores asociados antenatales, perinatales o posnatales, tanto de la madre como del niño, que tengan relevancia significativa en la aparición de trastornos del desarrollo.Pacientes y métodoSe creó una base de datos de todas las fichas clínicas de los pacientes con patología del desarrollo F80 a F90 CIE10 ingresados a la Unidad de Psiquiatría Infantil del Hospital Regional de Valdivia entre agosto de 2006 y diciembre de 2008. Total: 493 pacientes (48,7% del total de consultantes); grupo control de 32 niños sanos de consultorios de la ciudad. Se aplicó método estadístico odds ratio (95% confianza) para el análisis de algunas variables.ResultadosDestacan como factores de riesgo para desarrollar patología del desarrollo (p<0,005, 25% de frecuencia en población consultante): la prematurez, ser de sexo masculino, tener una madre con baja escolaridad, hospitalizaciones tempranas y enfermedades médicas antes de los 3 años (todos con odds ratio significativa). Además tener una madre psiquiátrica aumenta el doble el riesgo de desarrollar trastorno del desarrollo.ConclusiónSe requiere un trabajo colaborativo interdisciplinario entre neonatólogos, obstetras, psiquiatras infantiles y la atención primaria para detectar precozmente niños en riesgo.AbstractObjectivesTo study possible findings of factors in the antenatal, perinatal or postnatal period, in the mother or the child that may have an influence on the appearance of a developmental disorder.Patients and methodA Data Base of Clinical Histories from every patient with a developmental disorder (F80-F90 ICD10) was created. The patients attended the Child Psychiatric Unit at Hospital Regional of Valdivia, Chile, from August 2006 to December 2008. Total: 493 patientes (48.7% of the total of patients consulting); Control group: 32 healthy patients. Statistical method: odds ratio (95% confidence).ResultsThe main risk factors for developing a developmental disorder (P<.005, 25% frequency in the consulting population) are: prematurity, male sex, mother with low education, early hospitalizations, and medical illnesses (all with a significant odds ratio). Also, having a mother with psychiatric illness doubles the risk of having a developmental disorder.ConclusionIt requires an interdisciplinary collaborative work between neonatologists, obstetricians, child psychiatrists and the primary care to detect early children at risk
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