Norway rats (Rattus norvegicus) and black rats (Rattus rattus) are among the most prolific and widespread urban pest species in the world. Yet despite their ubiquity, a unified understanding of the ...ecology of these species in urban habitats eludes us. A comprehensive understanding of urban rat ecology is important for managing rat populations and mitigating the harmful effects that they may have on urban ecosystems (e.g., structural damage, food contamination, and disease spread). The objective of this systematic review and narrative synthesis is to collate, compare, and contrast data from the published literature regarding the ecology of Norway and black rats in urban centers. Themes emerging from the synthesis process, and discussed in detail, include population dynamics, behavior, movement, and environmental influences on rat populations.
It is well known that a wake will develop downstream of a tidal stream turbine owing to extraction of axial momentum across the rotor plane. To select a suitable layout for an array of horizontal ...axis tidal stream turbines, it is important to understand the extent and structure of the wakes of each turbine. Studies of wind turbines and isolated tidal stream turbines have shown that the velocity reduction in the wake of a single device is a function of the rotor operating state (specifically thrust), and that the rate of recovery of wake velocity is dependent on mixing between the wake and the surrounding flow. For an unbounded flow, the velocity of the surrounding flow is similar to that of the incident flow. However, the velocity of the surrounding flow will be increased by the presence of bounding surfaces formed by the bed and free surface, and by the wake of adjacent devices. This paper presents the results of an experimental study investigating the influence of such bounding surfaces on the structure of the wake of tidal stream turbines.
Inconel 718 samples were fabricated by selective laser melting (SLM). The effects of line laser energy densities in the range 0.1–0.3 J/mm on the microstructure, mechanical properties, and ...deformation of these samples were investigated. The fewest pores and best mechanical properties were realized at 0.2 J/mm with a yield strength of 775 MPa, ultimate tensile strength of 1055 MPa, and elongation of 29.5%. Fine dimples were uniformly distributed on the fracture surface under 0.2 J/mm. An Electron Backscatter Diffraction (EBSD) test revealed a mixture of fine columnar and equiaxed grains that promote strength while maintaining high plasticity. The prisms cut from these samples bent outwards, indicating great residual stresses in the samples. Their deformation increased with increasing laser energy density. Therefore, stress release treatment is necessary for SLM parts.
•The tensile strength and elongation reached 1055 MPa and 29.5%, respectively.•The best mechanical properties were achieved at 0.2 J/mm, instead of 0.3 J/mm.•Orderly stacking of melt pools without stagger caused tiny pores at the overlapping.•Prisms cut from specimens bent, the bigger energy density, the bigger deformation.
The glymphatic pathway expedites clearance of waste, including soluble amyloid β (Aβ) from the brain. Transport through this pathway is controlled by the brain's arousal level because, during sleep ...or anesthesia, the brain's interstitial space volume expands (compared with wakefulness), resulting in faster waste removal. Humans, as well as animals, exhibit different body postures during sleep, which may also affect waste removal. Therefore, not only the level of consciousness, but also body posture, might affect CSF-interstitial fluid (ISF) exchange efficiency. We used dynamic-contrast-enhanced MRI and kinetic modeling to quantify CSF-ISF exchange rates in anesthetized rodents' brains in supine, prone, or lateral positions. To validate the MRI data and to assess specifically the influence of body posture on clearance of Aβ, we used fluorescence microscopy and radioactive tracers, respectively. The analysis showed that glymphatic transport was most efficient in the lateral position compared with the supine or prone positions. In the prone position, in which the rat's head was in the most upright position (mimicking posture during the awake state), transport was characterized by "retention" of the tracer, slower clearance, and more CSF efflux along larger caliber cervical vessels. The optical imaging and radiotracer studies confirmed that glymphatic transport and Aβ clearance were superior in the lateral and supine positions. We propose that the most popular sleep posture (lateral) has evolved to optimize waste removal during sleep and that posture must be considered in diagnostic imaging procedures developed in the future to assess CSF-ISF transport in humans.
The rodent brain removes waste better during sleep or anesthesia compared with the awake state. Animals exhibit different body posture during the awake and sleep states, which might affect the brain's waste removal efficiency. We investigated the influence of body posture on brainwide transport of inert tracers of anesthetized rodents. The major finding of our study was that waste, including Aβ, removal was most efficient in the lateral position (compared with the prone position), which mimics the natural resting/sleeping position of rodents. Although our finding awaits testing in humans, we speculate that the lateral position during sleep has advantage with regard to the removal of waste products including Aβ, because clinical studies have shown that sleep drives Aβ clearance from the brain.
The mean wake of a three-bladed horizontal axis tidal stream turbine operating at maximum power coefficient has been investigated experimentally in a wide flume with width 11 times the depth, ...providing minimal restriction to transverse wake development and behaviour of large-scale horizontal turbulence structures. This is an important first stage for understanding wake interaction in turbine arrays and hence large-scale power generation. The rotor diameter has a typical value of 60% of the depth and the thrust coefficient is representative of a full-scale turbine. The shear layers originating from the rotor tip circumference show classic linear expansion downstream, with the rate of a plane shear layer vertically and 1.5 times that horizontally. These shear layers merge by around 2.5 diameters downstream forming a self-similar two-dimensional wake beyond eight diameters downstream with a virtual origin at two diameters downstream of the rotor plane. The spreading rate is somewhat less than that for solid bodies. The detailed velocity measurements made in the near wake show rotation and vorticity similar to that measured previously for wind and marine turbines although with asymmetry associated with bed and surface proximity. The longitudinal circulation in a transverse plane is conserved at about 1% of the swept circulation from the blade tip within two diameters downstream, the extent of detailed measurement. Turbines are usually designed using blade element momentum theory in which velocities at the rotor plane are characterised by axial and tangential induction factors and it is now possible to see how this idealisation relates to actual velocities. The axial induction factor corresponds to velocity deficits at 0.4–0.8 radii from the rotor axis across the near wake while the tangential induction factor at the rotor plane corresponds to velocities at 0.4–0.6 radii between 1–2 diameters downstream, indicating some general correspondence. For the two-dimensional self-similar far wake the two parameters defining the centreline velocity deficit and the transverse velocity profiles are likely to be insensitive to Reynolds number in turbulent conditions.
In this work, a Minkowski difference‐based advancing front approach is proposed to generate convex and non‐circular particles in a predefined computational domain. Two specific algorithms are ...developed to handle the contact conformity of generated particles with the boundaries of the computational domain. The first, called the open form, is used to handle the smooth contact of generated particles with (external) boundaries, while the other, called the closed form, is proposed to handle the internal boundaries of a computational domain with a complex cavity. The Gilbert‐Johnson‐Keerthi (GJK) method is used to efficiently solve the contact detection between the newly generated particle at the front and existing particles. Furthermore, the problem of one‐sided particle lifting, which can cause some defects in the packing structure in existing advancing front methods during packing generation, is highlighted and an effective solution is developed. Several examples of increasing complexity are used to demonstrate the efficiency and applicability of the proposed packing generation approach. The numerical results show that the generated packing is not only more uniform, but also achieves a higher packing density than existing advancing front methods.
The strength of the association between diabetes and risk of heart failure has differed between previous studies and the available studies have not been summarized in a meta-analysis. We therefore ...quantified the association between diabetes and blood glucose and heart failure in a systematic review and meta-analysis.
PubMed and Embase databases were searched up to May 3rd 2018. Prospective studies on diabetes mellitus or blood glucose and heart failure risk were included. A random effects model was used to calculate summary relative risks (RRs) and 95% confidence intervals (CIs). Seventy seven studies were included. Among the population-based prospective studies, the summary RR for individuals with diabetes vs. no diabetes was 2.06 (95% CIs: 1.73−2.46, I2 = 99.8%, n = 30 studies, 401495 cases, 21416780 participants). The summary RR was 1.23 (95% CI: 1.15–1.32, I2 = 78.2%, n = 10, 5344 cases, 91758 participants) per 20 mg/dl increase in blood glucose and there was evidence of a J-shaped association with nadir around 90 mg/dl and increased risk even within the pre-diabetic blood glucose range. Among the patient-based studies the summary RR was 1.69 (95% CI: 1.57–1.81, I2 = 85.5%, pheterogeneity<0.0001) for diabetes vs. no diabetes (n = 41, 100284 cases and >613925 participants) and 1.25 (95% CI: 0.89–1.75, I2 = 95.6%, pheterogeneity<0.0001) per 20 mg/dl increase in blood glucose (1016 cases, 34309 participants, n = 2). In the analyses of diabetes and heart failure there was low or no heterogeneity among the population-based studies that adjusted for alcohol intake and physical activity and among the patient-based studies there was no heterogeneity among studies with ≥10 years follow-up.
These results suggest that individuals with diabetes are at an increased risk of developing heart failure and there is evidence of increased risk even within the pre-diabetic range of blood glucose.
•Data regarding diabetes mellitus and heart failure have not been summarized.•A meta-analysis of 77 prospective studies was conducted.•Diabetes was associated with a 2-fold increase in heart failure risk in the general population.•Diabetes was associated with a 69% increase in heart failure risk in patient populations.•Elevated blood glucose even in the pre-diabetic range also increased heart failure risk.
A model has been devised to derive the intermetallic structure from the bcc- Fe unit cell. The fundamental finding is of special interest because the recent investigation clarifies that there is ...substantial evidence that atomic arrangements of transition metal-rich amorphous alloys are made of distorted bcc structure. The disordered bcc structure is thermodynamically in a metastable state, the heat treatment leads by crystallization of amorphous alloys to a stable state. In the past, a great deal has been made to describe the process of crystallization of amorphous alloys, but unfortunately, the disordered bcc-Fe regions of amorphous alloys have been neglected. Since the crystallization process takes place from the disordered bcc-regions of amorphous state, it is advisable to reexamine, discuss, and, where necessary to modify the product of the crystallization by the experimental achievements. It is therefore the objective of the present investigation to devise a model based on experimental facts. The atomic size of metalloid atoms determines the crystallization and crystal growth of amorphous alloy. Regardless of their structure, Mössbauer investigation on Fe-rich Metal-Metalloid alloys indicates that the metalloid atoms such as B, P, C, and Ge tend to act with iron by spending their electrons into the Fe 3d-band.
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