Isoenergetic Replacement of Fat by Starch in Diets for African Catfish (Clarias gariepinus): Effect on Water Fluxes in the Gastro Intestinal Tract

The effect of an isoenergetic replacement of dietary fat by starch, on chyme characteristics and water fluxes in the gastro intestinal tract (GIT) was assessed. Adult African catfish (Clarias gariepinus) were fed a starch (SD) or fat (FD) diet and groups of fish were dissected at 2, 5 and 8 h after the consumption of a single meal. Chyme was collected quantitatively and was analysed for osmolality and dry matter (DM) content. Postprandial water fluxes were calculated, while using yttrium oxide (Y2O3) as an inert marker to account for the absorption of DM along the GIT. The largest differences in chyme characteristics between diets were observed in the stomach and decreased towards subsequent compartments. A high initial osmotic pressure was measured in the stomach for both diets (up to 49862 mOsm kg21) and was likely the driver for the endogeneous water influx to this compartment. Large additions of water were recorded to the stomach and proximal intestine for both diets and absorption of water took place in the mid- and distal intestine. Interestingly, the dietary treatment had an impact on water balance in the stomach and proximal intestine of the fish, but not in the mid- and distal intestine. A strong complementary relationship suggested that 59% of the water fluxes in the proximal intestine could be explained by previous additions to the stomach. Therefore, a higher dietary inclusion of starch led to a shift in water additions from the proximal intestine to the stomach. However, the sum of water additions to the GIT was not different between diets and was on average 6.5260.85 ml water g21 DM. The interactions between osmoregulation and digestion, in the GIT of fed freshwater fish, deserve further attention in future research

Pinning of stripes by local structural distortions in cuprate high-Tc superconductors

We study the spin-density wave (stripe) instability in lattices with mixed low-temperature orthorhombic (LTO) and low-temperature tetragonal (LTT) crystal symmetry. Within an explicit mean-field model it is shown how local LTT regions act as pinning centers for static stripe formation. We calculate the modulations in the local density of states near these local stripe regions and find that mainly the coherence peaks and the van Hove singularity (VHS) are spatially modulated. Lastly, we use the real-space approach to simulate recent tunneling data in the overdoped regime where the VHS has been detected by utilizing local normal state regions.Comment: Conference proceedings for Stripes1

Keeping secrets from parents: Advantages and disadvantages of secrecy in adolescence.

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Role of vadose-zone flow processes in regional-scale hydrology: review, opportunities and challenges

At the regional scale, vadose-zone processes are recognized for controlling both short-term dynamics in watershed hydrology and long-term water balances of hydrologic basins. In this paper we explore the various conceptual and mathematical models that have been proposed or could be considered to represent water fluxes in the vadose zone at the catchment, watershed or regional scale. Such models have been in existence in two largely disconnected disciplines: on the one hand, watershed hydrologists and, more recently, climate modelers frequently conceptualize the vadose zone as a zero-dimensional black box represented by lumped parameter models. On the other hand, soil physicists, equipped with tools to measure system and systemstate properties directly in the vadose zone at scales of 10-2 – 100 m, have relied on Richards’ equation, a physically based, fully parameterized four-dimensional space– time model to represent unsaturated flow at the laboratory or field-plot scale. Over the past thirty years, the modeling efforts of the two disciplines have increasingly converged: hydrologists downscale their models by employing distributed (rather than lumped) models of varying complexity, while soil physicists have employed stochastic methods to upscale from their local-scale measurements and their localscale physical understanding of flow processes to the field and regional scale. The lead question in this work is how the typical small-scale vadose-zone measurements relate to the large-scale representative or ‘effective’ parameter values of variously complex regional vadose-zone models. Recent advances in both, downscaling (from the regional scale) and upscaling (from the laboratory scale) and the use of inverse models have led to promising tools. As a result, at the regional scale, the Richards’ equation and some of its simplifications, but also mass-balance and storage-based bucket models have been employed to represent spatially distributed unsaturated flow. All of these approaches have been employed with some success and under typically rather restrictive assumptions, whereby the least complex models seem to apply exclusively to the largest (and smallest) spatial and temporal scales. Various stochastic analyses have shown that simple averaging of local-scale measurements across the regions is associated with significant errors. Inverse modeling has relied on a priori assumptions about the physical framework that can be tested a posteriori. Both, downscaling and upscaling, regardless of the approach, yield increasingly complex models as they move from their opposing and well-understood starting points towards a unified mathematical representation that appropriately spans the hierarchy of significant process scales. To date, a physically and geostatistically consistent solution to describe regional vadose-zone flow in terms of local-scale measurements still eludes researcher

The source of dietary non-protein energy affects in vivo protein digestion in African catfish (Clarias gariepinus)

The development of chyme characteristics and the in vivo digestion of crude protein (CP) were assessed in response to different dietary sources of non-protein energy. African catfish (Clarias gariepinus) were fed a starch or fat diet for 28 days, and faecal CP apparent digestibility coefficient (ADC) was determined by a marker method. After the consumption of a single meal, chyme was collected from four compartments of the gastrointestinal tract and viscosity, dry matter (DM), CP and marker concentration were measured. Replacing dietary fat by starch resulted in a lower faecal CP ADC (P 0.05). Changes in macronutrient composition can alter the environment in which CP digestion takes place. We suggest that for the formulation of highly digestible diets, the entire feed matrix needs to be considered, rather than single ingredients

Lutetium-doped EuO films grown by molecular-beam epitaxy

The effect of lutetium doping on the structural, electronic, and magnetic properties of epitaxial EuO thin films grown by reactive molecular-beam epitaxy is experimentally investigated. The behavior of Lu-doped EuO is contrasted with doping by lanthanum and gadolinium. All three dopants are found to behave similarly despite differences in electronic configuration and ionic size. Andreev reflection measurements on Lu-doped EuO reveal a spin-polarization of 96% in the conduction band, despite non-magnetic carriers introduced by 5% lutetium doping. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4723570

Assessment of orchard N losses to groundwater with a vadose zone monitoring network

A 2-year study was conducted to explore the impact of current and alternative best management practices (BMPs) of irrigation and fertigation on nitrate (NO3 -) leaching below the root zone. Using a fully randomized complete block design, three fertigation strategies were compared: current BMP with and without accounting for NO3 --N in irrigation-water, and a high frequency fertigation treatment with low-N concentration applications. Temporal changes in water content, pore water NO3 - concentrations and soil water potential were monitored within and below the root zone to a soil depth of 3 m at eight sites in an almond and a pistachio orchard. NO3 - concentrations below the root zone ranged from <1 mg L-1 to more than 2400 mg L-1 (almond), and up to 11,000 (pistachio) mg L-1, with mean concentrations of 326 and 4631 mg L-1, respectively. Within the fertigation cycle, fertilizer injection at the end of an irrigation event generally resulted in lower NO3 - losses below the root zone compared with fertilizer injection midway through the irrigation. Pre-bloom and post-harvest flood irrigation in the almond orchard caused deep soil wetting and flushing of NO3 - below the root zone, threatening groundwater quality. Statistical analysis using principal component analysis, Chi-squared Automatic Interaction Detector and the Artificial Neural Network showed that most of the deep soil NO3 - concentration variability could not be explained by irrigation duration, fertigation timing or local variations in soil physical characteristics. However, mass balance estimates for water and N indicated the annual orchard average N loss could be estimated based on eight monitoring sites in spite of the inherent spatial variations in soil properties and the spatiotemporal variations in water and NO3 - applications. The study indicated that reduction of N losses at the orchard scale would require alternative fertigation and irrigation practices, including better control of fertigation amounts and irrigation duration. © 2016 Elsevier B.V