Abstract
A multiphysics and a stochastic kinetic-energy backscatter scheme are employed to represent model uncertainty in a mesoscale ensemble prediction system using the Weather Research and ...Forecasting model. Both model-error schemes lead to significant improvements over the control ensemble system that is simply a downscaled global ensemble forecast with the same physics for each ensemble member. The improvements are evident in verification against both observations and analyses, but different in some details. Overall the stochastic kinetic-energy backscatter scheme outperforms the multiphysics scheme, except near the surface. Best results are obtained when both schemes are used simultaneously, indicating that the model error can best be captured by a combination of multiple schemes.
Four model-error schemes for probabilistic forecasts over the contiguous United States with the WRF-ARW mesoscale ensemble system are evaluated in regard to performance. Including a model-error ...representation leads to significant increases in forecast skill near the surface as measured by the Brier score. Combining multiple model-error schemes results in the best-performing ensemble systems, indicating that current model error is still too complex to be represented by a single scheme alone. To understand the reasons for the improved performance, it is examined whether model-error representations increase skill merely by increasing the reliability and reducing the bias-which could also be achieved by postprocessing-or if they have additional benefits. Removing the bias results overall in the largest skill improvement. Forecasts with model-error schemes continue to have better skill than without, indicating that their benefit goes beyond bias reduction. Decomposing the Brier score into its components reveals that, in addition to the spread-sensitive reliability, the resolution component is significantly improved. This indicates that the benefits of including a model-error representation go beyond increasing reliability. This is further substantiated when all forecasts are calibrated to have similar spread. The calibrated ensembles with model-error schemes consistently outperform the calibrated control ensemble. Including a model-error representation remains beneficial even if the ensemble systems are calibrated and/or debiased. This suggests that the merits of model-error representations go beyond increasing spread and removing the mean error and can account for certain aspects of structural model uncertainty.
Aims/hypothesis
Obesity and insulin resistance are associated with low-grade chronic inflammation. Glucagon-like peptide-1 (GLP-1) is known to reduce insulin resistance. We investigated whether GLP-1 ...has anti-inflammatory effects on adipose tissue, including adipocytes and adipose tissue macrophages (ATM).
Methods
We administered a recombinant adenovirus (rAd) producing GLP-1 (rAd-GLP-1) to an
ob/ob
mouse model of diabetes. We examined insulin sensitivity, body fat mass, the infiltration of ATM and metabolic profiles. We analysed the mRNA expression of inflammatory cytokines, lipogenic genes, and M1 and M2 macrophage-specific genes in adipose tissue by real-time quantitative PCR. We also examined the activation of nuclear factor κB (NF-κB), extracellular signal-regulated kinase 1/2 and Jun N-terminal kinase (JNK) in vivo and in vitro.
Results
Fat mass, adipocyte size and mRNA expression of lipogenic genes were significantly reduced in adipose tissue of rAd-GLP-1-treated
ob/ob
mice. Macrophage populations (F4/80
+
and F4/80
+
CD11b
+
CD11c
+
cells), as well as the expression and production of IL-6, TNF-α and monocyte chemoattractant protein-1, were significantly reduced in adipose tissue of rAd-GLP-1-treated
ob/ob
mice. Expression of M1-specific mRNAs was significantly reduced, but that of M2-specific mRNAs was unchanged in rAd-GLP-1-treated
ob/ob
mice. NF-κB and JNK activation was significantly reduced in adipose tissue of rAd-GLP-1-treated
ob/ob
mice. Lipopolysaccharide-induced inflammation was reduced by the GLP-1 receptor agonist, exendin-4, in 3T3-L1 adipocytes and ATM.
Conclusions/interpretation
We suggest that GLP-1 reduces macrophage infiltration and directly inhibits inflammatory pathways in adipocytes and ATM, possibly contributing to the improvement of insulin sensitivity.
The ability to manipulate droplets on a substrate using electric signals
-known as digital microfluidics-is used in optical
, biomedical
, thermal
and electronic
applications and has led to ...commercially available liquid lenses
and diagnostics kits
. Such electrical actuation is mainly achieved by electrowetting, with droplets attracted towards and spreading on a conductive substrate in response to an applied voltage. To ensure strong and practical actuation, the substrate is covered with a dielectric layer and a hydrophobic topcoat for electrowetting-on-dielectric (EWOD)
; this increases the actuation voltage (to about 100 volts) and can compromise reliability owing to dielectric breakdown
, electric charging
and biofouling
. Here we demonstrate droplet manipulation that uses electrical signals to induce the liquid to dewet, rather than wet, a hydrophilic conductive substrate without the need for added layers. In this electrodewetting mechanism, which is phenomenologically opposite to electrowetting, the liquid-substrate interaction is not controlled directly by electric field but instead by field-induced attachment and detachment of ionic surfactants to the substrate. We show that this actuation mechanism can perform all the basic fluidic operations of digital microfluidics using water on doped silicon wafers in air, with only ±2.5 volts of driving voltage, a few microamperes of current and about 0.015 times the critical micelle concentration of an ionic surfactant. The system can also handle common buffers and organic solvents, promising a simple and reliable microfluidic platform for a broad range of applications.
•Part I explores the projectile impact response and damage of titanium-based fiber metal laminates (FMLs) using air gun set up.•The damage pattern, energy absorption, and opening of delamination ...between different layers are affected by distributing titanium layers through the thickness.•The ballistic resistance of FMLs is found to be independent of the dispersion of metallic layers within FMLs.•The lateral delamination spread, interlayer opening, and global bending deformation of titanium-based FMLs seem lower than aluminium-based FMLs.
This two-part article examines the distribution of metallic layers through the thickness of fiber metal laminates (FMLs) on their response and damage when subjected to high-velocity projectile impact. Glass fiber/epoxy and Ti-6Al-4V titanium alloy sheets are used to obtain four different layups of FMLs fabricating by the hand layup process and exhibiting the same thickness of the total metal layer. Part I deals with experimental investigations of fully clamped square FMLs normally impacting at the center by hemispherical steel projectile using compressed air gun set up. Different parameters are considered to evaluate the FMLs’ performance, which includes damage degree, first cracking energy, crack length, deformation profile, and damage developed on the surface and inside the laminate. The results indicate that the highest permanent deformation and cracking are exhibited by FML 4/3-0.3, exhibiting separation of composite layers with different orientations by the metallic layer. The other FMLs exhibit lower and approximately similar permanent deformations. However, lower cracking and a relatively higher lateral delamination spread and opening of the interlayer are exhibited by FML 2/1-0.6 in which composite layers are arranged together than FML 4/3-0.3, signifying that the damage spreading laterally can be reduced by dispensing titanium layers. The ballistic resistance is found to be similar for FMLs. The levels of permanent deformation, cracking, and delamination with their opening and spreading are lesser for titanium-based FMLs than aluminium-based FMLs. The ballistic response of FMLs will be evaluated using analytical modeling in an accompanying study (Part II).
Abstract
This paper presents the application of machine learning algorithms to identify pigs’ behaviors from data collected using the wireless sensor nodes mounted on pigs. The sensor node attached ...to a pig’s back senses the acceleration and angular velocity in three axes, and the sensed data are transmitted to a host computer wirelessly. Two video cameras, one attached to the ceiling of the pigpen and the other one to a fence, provided ground truth for data annotations. The data were collected from pigs for 131 h over 2 mo. As the typical behavior period depends on the behavior type, we segmented the acceleration data with different window sizes (WS) and step sizes (SS), and tested how the classification performance of different activities varied with different WS and SS. After exploring the possible combinations, we selected the optimum WS and SS. To compare performance, we used five machine learning algorithms, specifically support vector machine, k-nearest neighbors, decision trees, naive Bayes, and random forest (RF). Among the five algorithms, RF achieved the highest F1 score for four major behaviors consisting of 92.36% in total. The F1 scores of the algorithm were 0.98 for “eating,” 0.99 for “lying,” 0.93 for “walking,” and 0.91 for “standing” behaviors. The optimal WS was 7 s for “eating” and “lying,” and 3 s for “walking” and “standing.” The proposed work demonstrates that, based on the length of behavior, the adaptive window and step sizes increase the classification performance.
•Part II deals with the dynamic response of titanium-based FMLs undergoing ballistic impact using analytical modeling.•The leading part of the total energy absorption of FMLs is by bending and ...membrane energy absorption associated with the deformation of FML constituents (68 % - 72 %).•Varying placements of the titanium layers affect the partition of the energy absorption of FMLs.•The predicted ballistic resistance parameters of FMLs are found to be in good agreement with experiments.
This two-part article scrutinizes the influence of metal layer distribution through the thickness of titanium-based fiber metal laminates (FMLs) on their high-velocity projectile impact response and damage. The four different layups of FMLs consist of layers of glass fiber/epoxy and Ti-6Al-4V titanium alloy sheets, exhibiting the thickness of the total metal layer the same. Part I presents the experimental investigations of fully clamped FMLs demonstrating performance parameters, damage mechanisms, and ballistic resistance. Part II concerns the ballistic impact behavior of FMLs using analytical modeling, which is based on test results obtained in an accompanying study. An equivalent mass-spring system is used to obtain the transient deformation, ballistic limit, and absorbed energy of the laminate by various mechanisms. Good agreement is obtained between experimental and analytical ballistic limit velocity. The foremost part of the total energy absorption is by bending and membrane energy absorption (68 % - 72 %), with FML 4/3-0.3 absorbing a higher percentage of aforementioned energies followed by that of both FMLs 3/2 and FML 2/1-0.6. The predicted total energy absorption by several damage mechanisms of FMLs at the ballistic limit displays a reasonable matching with experiments.
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