Understanding the spatio‐temporal dynamics of runoff generation in headwater catchments is challenging, due to the intermittent and fragmented nature of surface flows. The active stream network in ...non‐perennial rivers contracts and expands, with a dynamic behavior that depends on the complex interplay among climate, topography, and geology. In this work, CATchment HYdrology, an integrated surface–subsurface hydrological model (ISSHM), is used to simulate the stream network dynamics of two virtual catchments with the same, spatially homogeneous, subsurface characteristics (hydraulic conductivity, porosity, water retention curves) but different morphology. We run two sets of simulations to reproduce a sequence of steady‐states at different catchment wetness levels and transient conditions and analyze the joint variations of the stream length (L) and discharge at the outlet (Q) with high spatio‐temporal resolutions. The shape of the L(Q) curves differs in the two catchments but does not depend on the climate forcing, as it is mainly controlled by the underlying topography. We then analyzed the suitability of the topographic wetness index and the contributing area to identify the spatial configuration of the maximum stream length in the two catchments. These two morphometric parameters provided a good estimate of the spatial distribution of the maximum flowing network in both the study catchments. Our numerical simulations indicate that ISSHMs have the potential to accurately describe the spatio‐temporal variations of the stream networks and the processes driving such dynamic behavior and that, overall, they can be useful tools to gain insights into the main physical drivers of non‐perennial streams.
Key Points
A physics‐based model is used to reproduce the spatiotemporal stream network dynamics of two virtual catchments with different morphology
The link between active stream length and outlet discharge is analyzed in steady‐state and transient conditions
Well‐established topographic indices can identify the maximum active network extent in catchments with homogeneous subsurface properties
Huntington's disease (HD) is a complex and severe disorder characterized by the gradual and the progressive loss of neurons, predominantly in the striatum, which leads to the typical motor and ...cognitive impairments associated with this pathology. HD is caused by a highly polymorphic CAG trinucleotide repeat expansion in the exon-1 of the gene encoding for huntingtin protein. Since the first discovery of the huntingtin gene, investigations with a consistent number of in-vitro and in-vivo models have provided insights into the toxic events related to the expression of the mutant protein. In this review, we will summarize the progress made in characterizing the signaling pathways that contribute to neuronal degeneration in HD. We will highlight the age-dependent loss of proteostasis that is primarily responsible for the formation of aggregates observed in HD patients. The most promising molecular targets for the development of pharmacological interventions will also be discussed.
Abstract
The boundary wall method (BWM) is a general purpose protocol to treat boundary value problems for wave equations, specially Helmholtz’s (the case addressed here). Similarly to most ...approaches, the BWM may be computationally demanding for large borders
C
, at which the wave function must satisfy specified boundary conditions. Also, despite the fact the BWM is an exact procedure, usually it is not amenable to closed form solutions. The BWM relies on the Green’s function
G
0
of the embedding domain
V
of
C
. However, in many instances—like for
C
modeling a billiard—the specific
V
is not really fundamental and thus one has a certain freedom to choose distinct domains and so
G
0
’s. Here we consider this characteristic of the BWM and show how to obtain some analytical results and solve numerically semi-infinite waveguides by exploring proper Green’s functions. As examples, we discuss rectangular, triangular and trapezoidal structures with both Dirichlet and leaking boundaries as well as scattering states within semi-infinite rectangular waveguides.
AISI 420 steel was plasma nitrided aiming to study the relationships between treatment temperature and the treated layer phase constitution and properties. Nitriding was carried out in temperatures ...varying from 200 to 600 °C for 4 h treatment time. Samples were characterized by OM, XRD and hardness measurements. For treatments carried out at 200 and 250 °C (here termed 'ultra-low' temperatures), it was observed the formation of N-expanded martensite ( ′ N phase) only. For low-temperatures (300 to 400 °C), the treated surfaces presented ′ N and epsilon-iron nitride ( -Fe2+xN) phases. At high temperatures (450 to 600 °C), -Fe2+xN and increasing amount of chromium nitrides (CrN and Cr2N phases) were verified in the nitrided layers with temperature rise. From 500 °C, the occurrence of gama'-iron nitride (γ′-Fe4N) was additionally noticed. Results also indicate that nitrided layer growth follows the Arrhenius law and presents two slopes in the Arrhenius plot. The activation energy for ultra-low and low temperatures is about two times smaller than that for high temperatures, suggesting two different growth mechanisms, probably one based on high-diffusivity paths (for the lower temperatures), and the other one on volume diffusion (for the higher temperatures), with activation energy of 64 16 and 119 12 kJ mol−1, respectively.
Low-temperature plasma carburizing was studied aiming to determine the effect of the gas mixture and flow rate on the surface properties of AISI 420 martensitic stainless steel samples. Plasma ...carburizing was carried out for gas mixtures of 20% Ar+80% H2 comprising CH4 contents between 0.25 and 1.00%, and gas flow rates ranging from 1.67×10−6 to 6.68×10−6Nm3s−1. The modified layers were characterized by confocal laser scanning microscopy, X-ray diffractometry and microhardness measurements. The plasma was also characterized by optical emission spectrometry. Results indicate the presence of a hard and thin outer layer and a carbon-enriched martensite diffusion layer. It is shown that gas mixture composition plays an important role in the process kinetics. Spectroscopic characterization of the glow discharge shows that the variation of the CH4 content in the gas mixture leads to a variation of the emission lines intensity but does not significantly alter the relative peak intensities. It suggests a variation on the plasma density and no significant variation on the active species. It also indicates that, for the studied conditions, the emission spectroscopy cannot be applied as a tool for process control.
► Carbides and expanded martensite are the main phases on the modified surface. ► Gas mixture composition significantly influences low temperature plasma carburizing. ► Equal or more than 1% CH4 contents in the gas mixture lead to soot formation. ► The total gas flow rate has minor influence on low temperature plasma carburizing. ► Optical emission spectroscopy cannot be applied to control the process.
The study aimed to assess the efficacy of an integrated water safety plan (WSP) in controlling Legionella re-growth in a respiratory hydrotherapy system located in a spa centre, supplied with ...sulphurous water, which was initially colonized by Legionella pneumophila. Heterotrophic plate counts, Pseudomonas aeruginosa, Legionella spp. were detected in water samples taken 6-monthly from the hydrotherapy equipment (main circuit, entry to benches, final outlets). On the basis of the results obtained by the continuous monitoring and the changes in conditions, the original WSP, including physical treatments of water and waterlines, environmental surveillance and microbiological monitoring, was integrated introducing a UV/ultrafiltration system. The integrated treatment applied to the sulphurous water (microfiltration/UV irradiation/ultrafiltration), waterlines (superheated stream) and distal outlets (descaling/disinfection of nebulizers and nasal irrigators), ensured the removal of Legionella spp. and P. aeruginosa and a satisfactory microbiological quality over time. The environmental surveillance was successful in evaluating the hazard and identifying the most suitable preventive strategies to avoid Legionella re-growth. Ultrafiltration is a technology to take into account in the control of microbial contamination of therapeutic spas, since it does not modify the chemical composition of the water, thus allowing it to retain its therapeutic properties.
Increasing interest in vegetable oils for use in green chemistry has stimulated research into high-erucic
Brassicaceae species such as winter oilseed rape (
Brassica napus L. var.
oleifera) and ...Ethiopian mustard (
Brassica carinata A. Braun). The objective of this study was to determine the yield response of recently released cultivars of these species under high and low production inputs. The varieties Maplus and Hearty of
B. napus, and BRK1 of
B. carinata were cultivated with autumn sowing in a large-scale field trial at the experimental farm of the University of Padova in Legnaro (NE Italy, 45°21′N). The genotypes were compared under high and low input management systems: high input was characterised by conventional soil tillage, chemical weed control, and high N–P–K fertilization, and low input by minimum tillage, mechanical weed control, and limited N–P–K fertilization.
Oilseed rape varieties had greater seed yield than BRK1, and interactions with input level and cultivation year were significant. Maplus yielded most at high input (3.78 vs. 3.31
t
ha
−1 DM at low; average of two years), whereas Hearty showed no significant differences between inputs (3.49
t
ha
−1; average of years and inputs), indicating its better adaptability to extensive agricultural management. Yield performance of BRK1
B. carinata was very stable at varying agricultural managements, but not very high (2.73
t
ha
−1 on average) – a fact that may limit its competitiveness with oilseed rape in autumn sowing, especially at higher latitudes.
B. carinata was also more variable across the years than oilseed rape in terms of seed yield, oil content, and percentage of erucic acid. This was mainly due to the particular climatic conditions of the second year of the experiment (mild winter; hot, dry spring) which led to considerable winter elongation and pre-flowering, and later to incomplete seed filling. In these conditions, BRK1 had both lower oil seed content (36.7% vs. 47.1%) and erucic acid (41.3% vs. 49.1%) than oilseed rapes.
In general, with few exceptions, the reduction in inputs did not affect either seed oil content or the amount of erucic acid, regardless of variety and year, but seed crude proteins were reduced mainly because of N shortage.
Wave confinement, e.g., in waveguides, gives rise to a huge number of distinct phenomena. Among them, amplitude gain is a recurrent and relevant effect in undulatory processes. Using a general ...purpose protocol to solve wave equations, the boundary wall method, we demonstrate that for relatively simple geometries, namely, a few leaky or opaque obstacles inside a θ wedge waveguide (described by the Helmholtz equation), one can obtain a considerable wave amplification in certain spatially localized regions of the system. The approach relies on an expression for the wedge waveguide exact Green's function in the case of θ=π/M (M=1,2,...), derived through the method of images allied to group theory concepts. The formula is particularly amenable to numerical calculations, greatly facilitating simulations. As an interesting by-product of the present framework, we are able to obtain the eigenstates of certain closed shapes (billiards) placed within the waveguide, as demonstrated for triangular structures. Finally, we briefly discuss possible concrete realizations for our setups in the context of matter and electromagnetic (for some particular modes and conditions) waves.
Aims: An evaluation was made of the prevalence of Legionella species in hot water distribution systems in the city of Bologna (Italy) and their possible association with bacterial contamination ...(total counts and Pseudomonadaceae) and the chemical characteristics of the water (pH, Ca, Mg, Fe, Mn, Cu, Zn and Total Organic Carbon, TOC).
Methods and Results: A total of 137 hot water samples were analysed: 59 from the same number of private apartments, 46 from 11 hotels and 32 from five hospitals, all using the same water supply. Legionella species were detected in 40·0% of the distribution systems, L. pneumophila in 33·3%. The highest colonization was found in the hot water systems of hospitals (93·7% of samples positive for L. pneumophila, geometric mean: 2·4 × 103 CFU l−1), followed by the hotels (60·9%, geometric mean: 127·3 CFU l−1) and the apartments with centralized heating (41·9%, geometric mean: 30·5 CFU l−1). The apartments with independent heating systems showed a lower level of colonization (3·6% for Legionella species), with no evidence of L. pneumophila. Correlation analysis suggests that copper exerts an inhibiting action, while the TOC tends to favour the development of L. pneumophila. No statistically significant association was seen with Pseudomonadaceae, which were found at lower water temperatures than legionellae and in individual distribution points rather than in the whole network.
Conclusions: The water recirculation system used by centralized boilers enhances the spreading of legionellae throughout the whole network, both in terms of the number of colonized sites and in terms of CFU count.
Significance and Impact of the Study: Differences in Legionella colonization between types of buildings are not due to a variation in water supply but to other factors. Besides the importance of water recirculation, the study demonstrates the inhibiting action of copper and the favourable action of TOC on the development of L. pneumophila.
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