Effects of an Inert, Palatable Resource Subsidy on Live Prey Selection by Juvenile Fish

Resource subsidies, defined as energy and nutrients that enter ecosystems from external sources, can have diverse and complex effects on consumer populations. For example, resource subsidies can increase consumer growth rates and survival by direct ingestion of the subsidy or by increasing populations of other natural prey. Excessive rates of resource subsidy addition, however, can reduce habitat quality through eutrophication. In this study, I tested the effects of three different rates of manufactured feed (i.e., a resource subsidy) provision (no feeding, 1%, or 3% body-weight/day; BW/d) on the foraging habits and growth rates of age-0 channel catfish (Ictalurus punctatus) in earthen ponds. I hypothesized that increased feeding rates would increase populations of zooplankton prey in ponds; alter the amount, composition, and preference of natural prey ingested by the fish; and reduce dissolved oxygen concentrations in ponds. I found that increasing the feeding rate did not increase the density or alter community composition of zooplankton in ponds. Although the feed was ingested by fish in the 1% and 3% BW/d ponds and increased fish growth, fish in all feeding treatments still ingested the same types and amounts of natural prey as they grew through time. Surprisingly, the fish ingested larger insects and chironomid larvae during early life and then switched to smaller zooplankton later, opposite of the pattern that has been observed for most other fishes. Finally, increasing the feeding rate decreased dissolved oxygen concentrations in ponds. From an applied aquaculture perspective, natural prey may have an important role in the growth of juvenile channel catfish. Future studies should further examine the interactive effects of resource subsidies, habitat quality, and consumer ontogeny on diet patterns in highly subsidized ecosystems.No embarg

Many-body dynamics of a Bose system with attractive interactions on a ring

We investigate the many-body dynamics of an effectively attractive one-dimensional Bose system confined in a toroidal trap. The mean-field theory predicts that a bright-soliton state will be formed when increasing the interparticle interaction over a critical point. The study of quantum many-body dynamics in this paper reveals that there is a modulation instability in a finite Bose system correspondingly. We show that Shannon entropy becomes irregular near and above the critical point due to quantum correlations. We also study the dynamical behavior of the instability by exploring the momentum distribution and the fringe visibility, which can be verified experimentally by releasing the trapComment: 6 pages,5 figure

Gastro-protective actions of Aloe barbadensis Miller mitigate ethanol-induced gastric injury in rats

Purpose: To investigate the gastroprotective effect of leaf extract of Aloe barbadensis on ethanolinduced gastric ulcer in rats.Methods: Healthy male Wistar rats (n = 30) weighing 180 - 220 g (mean weight = 200 ± 20 g) were randomly assigned to 6 groups (5 rats/group): control group, gastric ulcer group, two Aloe barbadensis extract groups (250 and 500 mg/kg), cimetidine group and indomethacin group. Gastric ulcer was induced via oral injection of absolute ethanol at a dose of 1 mL/kg after a 24-h fast. Gross evaluation, determination of gastric juice acidity and histological examination of gastric tissue were carried out.Results: Treatment of gastric ulcer rats with Aloe barbadensis extract significantly reduced ulcerated area (UA), ulcer index (UI), and acidity of gastric juice (p < 0.05). Injection of 1 % carrageenan into rat hind paw led to a time-dependent increase in paw volume which peaked 3 h after injection. However, the Aloe barbadensis extract significantly and dose-dependently reduced the volume of inflamed paw, and inhibited edema formation (p < 0.05). It also markedly reduced or completely eliminated edema and leucocyte infiltration. Moreover, treatment of gastric ulcer rats with Aloe barbadensis leaf extract led to significant and dose-dependent reduction in gastric tissue MDA level (p < 0.05). Histological examination of the gastric wall showed that control rats had severe injury in gastric mucosa,accompanied by edema and leucocytes infiltration, relative to rats pretreated with extract which showed marked gastric protection and inhibition of edema and leucocytes infiltration. Moreover, the extract treatment protected the gastric surface against ulceration as indicated by reduced lesions in the treated rat model.Conclusion: These results show that Aloe barbadensis mitigates ethanol-induced gastric injury in rats via inhibition of lipid  peroxidation and inflammation. Thus, the extract has potentials for development into a therapeutic agent for the management of  gastric ulcer. Keywords: Aloe barbadensis, Gastric ulcer, Gastric mucosa, Inflammation, Lipid peroxidatio

On the Convergence of Newton-type Proximal Gradient Method for Multiobjective Optimization Problems

In a recent study, Ansary (Optim Methods Softw 38(3):570-590,2023) proposed a Newton-type proximal gradient method for nonlinear multiobjective optimization problems (NPGMO). However, the favorable convergence properties typically associated with Newton-type methods were not established for NPGMO in Ansary's work. In response to this gap, we develop a straightforward framework for analyzing the convergence behavior of the NPGMO. Specifically, under the assumption of strong convexity, we demonstrate that the NPGMO enjoys quadratic termination, superlinear convergence, and quadratic convergence for problems that are quadratic, twice continuously differentiable and twice Lipschitz continuously differentiable, respectively.Comment: arXiv admin note: text overlap with arXiv:2306.0979

Human-induced vibration serviceability of arch pre-stressed concrete truss system

Human-induced vibration has become a serious serviceability problem due to the larger opening of girder, lighter floor systems and longer spans designed and used in practice. Vibration tests were undertaken in laboratory to research the vibrational characteristics of the arch pre-stressed concrete truss (APT) system spanning 16.0 m. Results from ambient vibration, impulse excitations (heel-drop and jumping) and steady-state incentives (walking and running) were presented. Dynamic characteristics such as natural frequencies, damping ratios, mode shapes and acceleration responses were studied and checked against the existing codes. Experimental results show that the investigated APT girder possesses high fundamental frequency and low damping ratio. Moreover, the perception factors based on the root-mean-square acceleration, vibration dose value (VDV) and psychological comfort data were obtained. Lastly, the threshold accelerations and VDVs were suggested for evaluating the human-induced vibration

A threshold dislocation dynamics method

The Merriman-Bence-Osher threshold dynamics method is an efficient algorithm to simulate the motion by mean curvature. It has the advantages of being easy to implement and with high efficiency. In this paper, we propose a threshold dynamics method for dislocation dynamics in a slip plane, in which the spatial operator is essentially an anisotropic fractional Laplacian. We show that this threshold dislocation dynamics method is able to give { two correct leading orders} in dislocation velocity, including both the $O(\log\varepsilon)$ local curvature force and the $O(1)$ nonlocal force due to the long-range stress field generated by the dislocations as well as the force due to the applied stress, where $\varepsilon$ is the dislocation core size, { if the time step is set to be $\Delta t=\varepsilon$. This generalizes the available result of threshold dynamics with the corresponding fractional Laplacian, which is on the leading order $O(\log\Delta t)$ local curvature velocity under the isotropic kernel.} We also propose a numerical method based on spatial variable stretching to correct the mobility and to rescale the velocity for efficient and accurate simulations, which can be applied generally to any threshold dynamics method. We validate the proposed threshold dislocation dynamics method by numerical simulations of various motions and interaction of dislocations.Comment: 35 pages, 13 figure