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Thermodynamic stability of niobium-doped ceria surfaces
No full textCeria (CeO2) displays a profound catalytic capacity even when utilized as a stand-alone material. Catalyzed reactions by ceria could be enhanced when it is decorated with a trace content of d or f-metals. This study addresses the stability and properties of niobium incorporated ceria surfaces. Doping a trace amount of metals often alter catalytic properties of the host metal oxide. Herein, we investigate mixed Ce-Nb-O oxides with a prime focus on the surface free energy, lattice constant, as well as atomic charges and density of states. It was found that the most stable Ce-Nb-O configuration is obtained when Nb atoms supersede top-layer O atoms at highest niobium occupancy where the surface energy decreases by 0.3 eV/Å2 compared to neat ceria surface. It was also shown that the changes in lattice constants in this configuration is in accord with data obtained from X-Ray Diffraction patterns. Results from this study could be useful in fine-tuning catalytic attributes of ceria-based materials
Parameter estimation for robotic manipulator systems
Get PDFIn this paper, a novel methodology for estimating the parameters of robotic manipulator systems is proposed. It can be seen that, for the purpose of parameter estimation, the input torque to each joint motor is designed as a linear combination of sinusoids. After the transient responses of joint angles exponentially converge to zero, the steady states of joint angle outputs can be extracted. Since the steady states of joint angles are the equivalent finite Fourier series, the coefficients of the steady state components of joint angles can be further extracted in a fundamental period. With the amazing finding that the steady states contain all dynamic information of manipulator systems, all unknown parameters of the system model can be accurately estimated with the extracted coefficients in finite frequency bands. The simulation results for a two-link manipulator are carried out to illustrate the effectiveness and robustness against measurement noise of the proposed method
Success of post-fire plant recovery strategies varies with shifting fire seasonality
Get PDFWildfires are increasing in size and severity and fire seasons are lengthening, largely driven by climate and land-use change. Many plant species from fire-prone ecosystems are adapted to specific fire regimes corresponding to historical conditions and shifts beyond these bounds may have severe impacts on vegetation recovery and long-term species persistence. Here, we conduct a meta-analysis of field-based studies across different vegetation types and climate regions to investigate how post-fire plant recruitment, reproduction and survival are affected by fires that occur outside of the historical fire season. We find that fires outside of the historical fire season may lead to decreased post-fire recruitment, particularly in obligate seeding species. Conversely, we find a general increase in post-fire survival in resprouting species. Our results highlight the trade-offs that exist when considering the effects of changes in the seasonal timing of fire, an already present aspect of climate-related fire regime change
A prospective ex vivo biomechanical analysis of retrievable inferior vena cava filters
No full textObjective
In the present study, we investigated the structural integrity of inferior vena cava (IVC) filters after their retrieval.
Methods
A prospective ex vivo biomechanical analysis was performed of the structural integrity of 100 IVC filters used in a randomized controlled trial to evaluate the effectiveness of prophylactic IVC filters in preventing mortality or symptomatic pulmonary embolism in major trauma patients.
Results
Of the 100 included patients, 7 (7%) had required more than one attempt to remove the filter. The median duration of the filter left in situ was 54 days (interquartile range, 17-101 days). During the initial attempt to remove six filters (6%), thrombi were found entrapped and required 4 weeks of systemic anticoagulation therapy before the filters could be removed in a second attempt. A positive correlation was found between the duration of the filter left in situ and the loss in metallic elasticity of the nitinol alloy of the filter struts (Pearson correlation coefficient, 0.232; P = .008). One filter was adherent to the IVC wall and required open surgical removal 227 days after its initial placement. One of the six long struts of the filter had been fractured during the removal process, with evidence of hardening to bending stress in the remaining five struts of the fractured filter compared with the struts of the 25 intact filters. Fibrous endothelial tissue (73%) and thrombi (33%) adherent to the retrieved filters were frequently observed. The presence of adherent fibrous tissue was not significantly related statistically to the duration of the filter left in situ (P = .353) but was more common among the patients who had had a delay in receiving prophylactic anticoagulation therapy (mean difference, 2 days; 95% confidence interval, 0.6-3.3; P = .039).
Conclusions
Metallic fatigue might account for IVC filter strut fractures. Fibrous endothelial tissue adherent to the filters was common, especially for those with a delay in receiving prophylactic anticoagulation therapy
Expression profile of CYP402C1 and its role in resistance to imidacloprid in the whitefly, Bemisia tabaci
No full textBemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a cosmopolitan insect pest causing serious damage to crop production. Cytochromes P450 (CYPs) of B. tabaci are widely known to be involved in the metabolic resistance to a variety of insecticides, continuously increasing the difficulty in controlling this pest. In this study, four P450 genes (CYP6CM1, CYP6CX1, CYP6CX3, and CYP402C1) in B. tabaci exhibited correlations with the resistance to imidacloprid. We have focused on trying to understand the function and metabolism capacity of CYP402C1. The expression profiles of CYP402C1 were examined by reverse transcription quantitative real-time PCR and fluorescence in situ hybridizations. Its role in resistance to imidacloprid was investigated by RNA interference, transgenic Drosophila melanogaster, and heterologous expression. The results showed that CYP402C1 was highly expressed in the active feeding stages of B. tabaci, such as nymphs and female adults. CYP402C1 was mainly expressed in midguts of nymphs and adults, especially in the filter chamber. Knockdown of CYP402C1 significantly decreased the resistance of B. tabaci to imidacloprid by 3.96-fold (50% lethal concentration: 186.46 versus 47.08 mg/L). Overexpression of CYP402C1 in a transgenic D. melanogaster line (Gal4 > UAS-CYP402C1) significantly increased the resistance to imidacloprid from 12.68- to 14.92-fold (129.01 and 151.80 mg/L versus 1925.14 mg/L). The heterologous expression of CYP402C1 showed a metabolism ability of imidacloprid (imidacloprid decreased by 12.51% within 2 h). This study provides new insights for CYP402C1 function in B. tabaci and will help develop new strategies in B. tabaci control and its insecticide resistance
Globalising the ‘war on terror’? An analysis of 36 countries
No full textThe war on terror as a discourse assumes that terrorism is an essential threat of global proportions, is mostly perpetuated by Islamist networks, and requires a strong international response. This discourse had tremendous impacts on both domestic and international politics. Consequentially, a large number of studies analyse the assumptions underlying and the policies legitimised by the war on terror discourse. However, existing work mostly focusses on one or a few cases, predominantly in the global north. This article introduces a novel dataset containing information on the war on terror discourse in the school textbooks of 36 countries, representing around 64% of the world’s population, for the period 2003–2014. Based on this dataset, I present the first comprehensive analysis of the global diffusion of the war on terror discourse. The study finds that the discourse has by no means globalised but is mostly limited to wealthy countries in Europe and North America. There are hence clear limits to the USA’s soft power and the hyper-globalisation of terrorism discourses. Factors like terrorism intensity, armed conflict and authoritarian regime have little predictive power. This is despite clear incentives for challenged (authoritarian) regimes to adapt the war on terror discourse. Contrary to common assumptions in critical security and terrorism studies, the war on terror discourse is hardly associated with an emphasis on terrorists’ irrationality and hatred or with the marginalisation of socio-political grievances
Positive selection of mutations in the Helicobacter pylori katA 5′ untranslated region in a Mongolian Gerbil Model of gastric disease
No full textTo evaluate potential effects of gastric inflammation on Helicobacter pylori diversification and evolution within the stomach, we experimentally infected Mongolian gerbils with an H. pylori strain in which Cag type IV secretion system (T4SS) activity is controlled by a TetR/tetO system. Gerbils infected with H. pylori under conditions in which Cag T4SS activity was derepressed had significantly higher levels of gastric inflammation than gerbils infected under conditions with repressed Cag T4SS activity. Mutations in the 5′ untranslated region (UTR) of katA (encoding catalase) were detected in strains cultured from 8 of the 17 gerbils infected with Cag T4SS-active H. pylori and none of the strains from 17 gerbils infected with Cag T4SS-inactive H. pylori. Catalase enzymatic activity, steady-state katA transcript levels, and katA transcript stability were increased in strains with these single nucleotide polymorphisms (SNPs) compared to strains in which these SNPs were absent. Moreover, strains harboring these SNPs exhibited increased resistance to bactericidal effects of hydrogen peroxide, compared to control strains. Experimental introduction of the SNPs into the wild-type katA 5′ UTR resulted in increased katA transcript stability, increased katA steady-state levels, and increased catalase enzymatic activity. Based on site-directed mutagenesis and modeling of RNA structure, increased katA transcript levels were correlated with higher predicted thermal stability of the katA 5′ UTR secondary structure. These data suggest that high levels of gastric inflammation positively select for H. pylori strains producing increased levels of catalase, which may confer survival advantages to the bacteria in an inflammatory gastric environment
Farmers’ fertilizer use gaps relative to government recommendations in the saline coastal zone of the Ganges Delta
No full textOveruse or underuse of nutrients relative to recommendations is a likely cause of crop yield gaps and an impediment to the achievement of food security. Government-endorsed recommendations are developed to deliver the best evidence-based advice on balanced fertilizer; however, deviations of farmers’ nutrient use from the recommendations are rarely examined. This study chose the salt-affected coastal zone of the Ganges Delta, where low crop productivity and cropping intensity by smallholders limit their income, to determine current nutrient use gaps for the first time of three cropping patterns in two representative districts of Bangladesh. A total of 246 farms were surveyed from three farm sizes. Farmers’ nutrient use gaps were compared with Fertilizer Recommendation Guides published in 2012 (FRG-2012) and 2018 (FRG-2018). Relative to FRG-2012 recommendations, farmers used 12%, 70%, and 11% overdoses of N, P, and K, respectively, under two fully rice-based cropping patterns, but the level of overdoses increased with farm size. Rates of K (14%), S (28%), and Zn use were below the FRG-2012 recommendations, especially for the smallest category of farms. However, the FRG-2018, increased recommended N (5%), K (62%), S (12%), and Zn rates but reduced P (25%) rates for fully rice-based cropping patterns. In contrast with rice, regardless of farm size, farmers applied overdose nutrients to watermelon but compensated with underdoses in the subsequent monsoon rice implying that farmers prioritized fertilizer expenditure on the most profitable crop. For the cropping pattern with watermelon, farmers could reduce the use of N (69%) and P (46%) and increase the use of K (48%), S (5%), and B. Reducing NPK use gaps can save treasury for both the farmers and the governments by 39.1 and 73.8 USD ha-1, respectively, under fully rice-based cropping patterns. Finally, our findings suggest there is scope to promote crop yields and sustainable intensification through balanced fertilizer use in a vulnerable saline region
Extraction of density-layered fluid from a porous medium
Get PDFWe consider axisymmetric flow towards a point sink from a stratified fluid in a vertically confined aquifer. We present two approaches to solve the equations of flow for the linear density gradient case. Firstly, a series method results in an eigenfunction expansion in Whittaker functions. The second method is a finite difference method. Comparison of the two methods verifies the finite difference method is accurate, so that more complicated nonlinear, density stratification can be considered. Interesting results for the case where the density stratification changes from linear to almost two-layer are presented, showing that in the nonlinear stratification case, there are certain values of flow rate for which a steady solution does not occur. A spectral method is then implemented to consider cases in which there is a stagnant region beneath a sharp interface between two layers of different, but constant, density. In this situation, flows also exist only for flow rates beneath a critical flux value, consistent with the results for the continuous density stratification
Valued living among veterans in breath-based meditation treatment or cognitive processing therapy for posttraumatic stress disorder: Exploratory outcome of a randomized controlled trial
Get PDFBackground
Valued living is the extent to which an individual’s behavior is consistent with what they believe is important or good. It is unknown whether many complementary and integrative treatments and psychotherapies for posttraumatic stress disorder enhance valued living, and for whom.
Objectives
Measure within- and between-group changes in valued living in Veterans who completed cognitive processing therapy (CPT) and sudarshan kriya yoga (SKY) for posttraumatic stress disorder (PTSD); evaluate moderators of improvement.
Methods
Participants with clinically significant symptoms of PTSD were assigned to CPT, a first line, evidence-based psychotherapy for PTSD or SKY, an emerging breath-based meditation with strong preliminary empirical support in a parallel-groups randomized controlled trial at a single Veterans Affairs healthcare center. The Valuing Questionnaire subscales for progress in valued living (VQ-P) and obstruction in valued living (VQ-O) were exploratory outcome measures. Assessors were blind to treatment assignment.
Results
59 participants completed treatment (29 CPT, 30 SKY). Participants in the CPT group improved from baseline to end of treatment in both VQ-Progress (d=0.55, p=0.02) and VQ–Obstruction (d=-0.51, p=0.03), while the SKY group did not improve on either subscale (d=0.08, p=0.69; d=0.00, p=1.00). However, differences between treatments were not statistically significant (p=0.16, 0.11, respectively). Participants reporting less valued living and more depression symptoms at baseline reported greater improvements in valued living following treatment.
Conclusion
CPT may have a positive effect on valued living. Individuals lower in valued living and with more depression may derive relatively more benefit