bluuebunny/crossref_metadata_2025 huggingface dataset:
Urbanization is associated with modifications in DNA methylation in a small passerine bird
Authors: Watson Hannah , Powell Daniel , Salmón Pablo , Jacobs Arne , Isaksson Caroline
Published: October 2020

Urbanization represents a fierce driver of phenotypic change, yet the molecular mechanisms underlying observed phenotypic patterns are poorly understood. Epigenetic changes are expected to facilitate more rapid adaption to changing or novel environments, such as our towns and cities, compared with slow changes in gene sequence. A comparison of liver and blood tissue from great tits Parus major originating from an urban and a forest site demonstrated that urbanization is associated with variation in genome‐wide patterns of DNA methylation. Combining reduced representation bisulphite sequencing with transcriptome data, we revealed habitat differences in DNA methylation patterns that suggest a regulated and coordinated response to the urban environment. In the liver, genomic sites that were differentially methylated between urban‐ and forest‐dwelling birds were over‐represented in regulatory regions of the genome and more likely to occur in expressed genes. DNA methylation levels were also inversely correlated with gene expression at transcription start sites. Furthermore, differentially methylated CpG sites, in liver, were over‐represented in pathways involved in (i) steroid biosynthesis, (ii) superoxide metabolism, (iii) secondary alcohol metabolism, (iv) chylomicron remodelling, (v) cholesterol transport, (vi) reactive oxygen species (ROS) metabolic process and (vii) epithelial cell proliferation. This corresponds with earlier studies identifying diet and exposure to ROS as two of the main drivers of divergence between organisms in urban and nonurban environments. Conversely, in blood, sites that were differentially methylated between urban‐ and forest‐dwelling birds were under‐represented in regulatory regions, more likely to occur in nonexpressed genes and not over‐represented in specific biological pathways. It remains to be determined whether diverging patterns of DNA methylation represent adaptive evolutionary responses and whether the conclusions can be more widely attributed to urbanization.
Up in the air: Threats to Afromontane biodiversity from climate change and habitat loss revealed by genetic monitoring of the Ethiopian Highlands bat
Authors: Razgour Orly , Kasso Mohammed , Santos Helena , Juste Javier
Published: October 2020

While climate change is recognized as a major future threat to biodiversity, most species are currently threatened by extensive human‐induced habitat loss, fragmentation and degradation. Tropical high‐altitude alpine and montane forest ecosystems and their biodiversity are particularly sensitive to temperature increases under climate change, but they are also subject to accelerated pressures from land conversion and degradation due to a growing human population. We studied the combined effects of anthropogenic land‐use change, past and future climate changes and mountain range isolation on the endemic Ethiopian Highlands long‐eared bat, Plecotus balensis, an understudied bat that is restricted to the remnant natural high‐altitude Afroalpine and Afromontane habitats. We integrated ecological niche modelling, landscape genetics and model‐based inference to assess the genetic, geographic and demographic impacts of past and recent environmental changes. We show that mountain range isolation and historic climates shaped population structure and patterns of genetic variation, but recent anthropogenic land‐use change and habitat degradation are associated with a severe population decline and loss of genetic diversity. Models predict that the suitable niche of this bat has been progressively shrinking since the last glaciation period. This study highlights threats to Afroalpine and Afromontane biodiversity, squeezed to higher altitudes under climate change while losing genetic diversity and suffering population declines due to anthropogenic land‐use change. We conclude that the conservation of tropical montane biodiversity requires a holistic approach, using genetic, ecological and geographic information to understand the effects of environmental changes across temporal scales and simultaneously addressing the impacts of multiple threats.
A review of oestrus suppression techniques in mares
Authors: Crabtree J. R.
Published: October 2020

Many fillies and mares are accused of behaving badly by their owners or trainers, and their reproductive hormones and ovaries are commonly blamed for this. Overt oestrus behaviour, however natural, is undesirable when a horse is being ridden, trained and competed. More subtle behaviours may be attributed to the reproductive cycle and presented as the cause of poor performance in the elite competition mare. Sometimes behaviours are complex, perhaps at odds with what one expects for normal reproductive behaviour and in many cases may not be associated with the reproductive cycle at all, rather associated with pain of musculoskeletal or soft tissue origin. The situation represents a diagnostic dilemma to positively associate undesirable behaviours with the ovarian hormones or ovarian pain, before an attempt can be made to modify the behaviour through the suppression of oestrus. This article will review the reasons for presentation, the behavioural patterns of the reproductive cycle and the diagnosis of reproductive behavioural problems. The range of techniques for oestrus suppression will be reviewed along with their clinical application and any known current regulatory issues associated with their use.
Fatigue analysis and fracture toughness of graphene reinforced carbon fibre polymer composites
Authors: Tareq Md Sarower , Jony Bodiuzzaman , Zainuddin Shaik , Al Ahsan Mohammad , Hosur Mahesh V.
Published: October 2020

Three‐point flexural fatigue behaviour and mode I interlaminar fracture toughness of the carbon fibre reinforced polymer composites (CFRPCs) modified by the addition of graphene nanoplatelet (GnP) were investigated. CFRPCs without any addition of nanoparticles were also tested as control samples. Fatigue life was characterized by the two parameter Weibull distribution function and predicted using the combined Weibull and Sigmoidal model. It was found that incorporation of very small amount (0.1%) of GnP in the epoxy polymer matrix improved mean and predicted fatigue life up to 155% and 190% (0.5 failure probability), respectively. The critical mode I interlaminar fracture toughness of the GnP reinforced composites was found up to 40% higher than the control samples. The improvement achieved by incorporating GnP is discussed in terms of crack deflection mechanism by nanoparticles and scanning electron micrograph images of the fracture specimens that revealed strong interfacial bonding in the nanoreinforced specimens.
A nonrandom walk down Hollywood boulevard: Celebrity deaths and investor sentiment
Authors: Lepori Gabriele M.
Published: October 2020

Motivated by psychological evidence that shows the public experiences emotional distress in response to the deaths of popular figures, I employ the deaths of 1,391 Hollywood Walk of Fame celebrities as natural experiments to identify exogenous public mood changes over the period 1926–2009. Consistent with the psychological theories which maintain that sadness encourages individuals to favor high‐risk/high‐reward investments, I find that U.S. stock returns are abnormally high immediately after the death of a major celebrity. This effect is particularly large during periods of high market‐level uncertainty (+0.40%) and for stocks headquartered in the city where the celebrity died (+0.26%).
Much stronger tundra methane emissions during autumn freeze than spring thaw
Authors: Bao Tao , Xu Xiyan , Jia Gensuo , Billesbach David P. , Sullivan Ryan C.
Published: October 2020

Warming in the Arctic has been more apparent in the non‐growing season than in the typical growing season. In this context, methane (CH4) emissions in the non‐growing season, particularly in the shoulder seasons, account for a substantial proportion of the annual budget. However, CH4 emissions in spring and autumn shoulders are often underestimated by land models and measurements due to limited data availability and unknown mechanisms. This study investigates CH4 emissions during spring thaw and autumn freeze using eddy covariance CH4 measurements from three Arctic sites with multi‐year observations. We find that the shoulder seasons contribute to about a quarter (25.6 ± 2.3%, mean ± SD) of annual total CH4 emissions. Our study highlights the three to four times higher contribution of autumn freeze CH4 emission to total annual emission than that of spring thaw. Autumn freeze exhibits significantly higher CH4 flux (0.88 ± 0.03 mg m−2 hr−1) than spring thaw (0.48 ± 0.04 mg m−2 hr−1). The mean duration of autumn freeze (58.94 ± 26.39 days) is significantly longer than that of spring thaw (20.94 ± 7.79 days), which predominates the much higher cumulative CH4 emission during autumn freeze (1,212.31 ± 280.39 mg m−2 year−1) than that during spring thaw (307.39 ± 46.11 mg m−2 year−1). Near‐surface soil temperatures cannot completely reflect the freeze–thaw processes in deeper soil layers and appears to have a hysteresis effect on CH4 emissions from early spring thaw to late autumn freeze. Therefore, it is necessary to consider commonalities and differences in CH4 emissions during spring thaw versus autumn freeze to accurately estimate CH4 source from tundra ecosystems for evaluating carbon‐climate feedback in Arctic.
Method to Estimate Thermal Conductivity of Subsurface Media
Authors: Karimi Askarani Kayvan , Gallo Sam , Kirkman Andrew J. , Sale Tom C.
Published: October 2020

Thermal conductivity is an essential parameter in heat transfer models including soil‐water systems. Herein, an Internet of Things (IoT) tool and a computational method are advanced for vertically resolving in situ thermal conductivity values in soil‐groundwater systems. A demonstrative application of this approach at a former petroleum refinery is presented. A line heat source is co‐located with a vertical string of in situ temperature sensors. Five‐minute multiple level temperature data were collected before, during, and after a 100‐min long heating period. Vertically distributed temperature data are transformed into vertically discretized thermal conductivity values using an analytical solution. Results fall in the range of thermal conductivity values reported in the literature. Specifically, estimated thermal conductivity values from 0.3 to 7.3 m below ground surface range between 0.7 and 5.4 (W/m/C) with the highest values occurring in media with greater water content. Overall, the advanced method in this study provides a pragmatic approach for vertically resolving subsurface thermal conductivity values applicable for many scientific disciplines.
Processing of MAX phases: From synthesis to applications
Authors: Gonzalez‐Julian Jesus
Published: October 2020

MAX phases are a large family of materials with more than 150 different compositions that have been extensively investigated during the last 25 years. They present a layered structure and a unique combination of properties, bridging the gap between metallic and ceramic properties. However, despite their excellent response of some compositions at high temperature—excellent oxidation resistance up to 1400°C under corrosive environment, good damage and radiation tolerance, thermal shock resistance, and self‐crack healing—their transfer to applications has been limited by three main factors: i) complexity of this large family of materials, ii) unavailability of highly pure commercial powders, and iii) extensive time to license products in strategic fields such as nuclear or aviation. In this article, the main properties and synthesis routes are reviewed, including solid state reaction methods, physical vapor deposition (PVD) techniques and molten salt processes. Emphasis is given to processing routes for developing different structures such as dense bulk samples, ceramic matrix composites, foams with different porosity, coatings by PVD and thermal spray technologies, and near net shaping by slip casting, injection molding, and additive manufacturing. Well‐known and novel potential applications are described such as structural materials for high temperature applications, protective coatings and bond‐coats for gas turbines, accident tolerant fuel cladding in nuclear power plants, solar receiver in concentrated solar power systems, electrical contacts, catalyst, and joining material. Finally, high impact investigations and future challenges are listed in order to facilitate the transfer of MAX phases to the market.
Androgen receptor suppresses vasculogenic mimicry in hepatocellular carcinoma via circRNA7/miRNA7‐5p/VE‐cadherin/Notch4 signalling
Authors: Bao Shixiang , Jin Shuai , Wang Chunhua , Tu Peipei , Hu Kongwang , Lu Jingtao
Published: October 2020

Androgen receptor (AR) can suppress hepatocellular carcinoma (HCC) invasion and metastasis at an advanced stage. Vasculogenic mimicry (VM), a new vascularization pattern by which tumour tissues nourish themselves, is correlated with tumour progression and metastasis. Here, we investigated the effect of AR on the formation of VM and its mechanism in HCC. The results suggested that AR could down‐regulate circular RNA (circRNA) 7, up‐regulate micro RNA (miRNA) 7‐5p, and suppress the formation of VM in HCC Small hairpin circR7 (ShcircR7) could reverse the impact on VM and expression of VE‐cadherin and Notch4 increased by small interfering AR (shAR) in HCC, while inhibition of miR‐7‐5p blocked the formation of VM and expression of VE‐cadherin and Notch4 decreased by AR overexpression (oeAR) in HCC. Mechanism dissection demonstrated that AR could directly target the circR7 host gene promoter to suppress circR7, and miR‐7‐5p might directly target the VE‐cadherin and Notch4 3′UTR to suppress their expression in HCC. In addition, knockdown of Notch4 and/or VE‐cadherin revealed that shVE‐cadherin or shNotch4 alone could partially reverse the formation of HCC VM, while shVE‐cadherin and shNotch4 together could completely suppress the formation of HCC VM. Those results indicate that AR could suppress the formation of HCC VM by down‐regulating circRNA7/miRNA7‐5p/VE‐Cadherin/Notch4 signals in HCC, which will help in the design of novel therapies against HCC.
Alterations in the phosphodiesterase type 5 pathway and oxidative stress correlate with erectile function in spontaneously hypertensive rats
Authors: He Weixiang , Liu Jianmin , Liu Daoquan , Hu Jundong , Jiang Ye , Li Mingzhou , Wang Qian , Chen Ping , Zeng Guang , Xu Deqiang , Wang Xinghuan , DiSanto Michael E. , Zhang Xinhua
Published: October 2020

To explore how alterations in the phosphodiesterase type 5 (PDE5) signalling pathway and oxidative stress correlate with changes in the expression of relaxation and contraction molecules and erectile dysfunction (ED) in the corpus cavernosum smooth muscle (CCSM) of spontaneously hypertensive rats (SHR). In this study, SHR and Wistar‐Kyoto (WKY) rats were used. Erectile function was determined by apomorphine test and electrical stimulation (ES) of cavernous nerve. Masson's trichrome staining and confocal microscopy were performed. Nitric oxide synthase (NOS), PDE5, phosphorylated‐PDE5 and α1‐adrenergic receptor (α1AR) were determined by RT‐PCR and Western blotting while oxidative stress in CC was determined by colorimetric analysis. SHR exhibited obvious ED. CC of SHR showed less SM but more collagen fibres. The expression of NOS isoforms in SHR was significantly decreased while all α1AR isoforms were increased. In addition, PDE5 and phosphorylated‐PDE5 were down‐regulated and its activity attenuated in the hypertensive rats. Meanwhile, the SHR group suffered oxidative stress, which may be modulated by endoplasmic reticulum stress and NADPH oxidase up‐regulation. Dysregulation of NOS and α1AR, histological changes and oxidative stress in CC may be associated with the pathophysiology of hypertension‐induced ED. In addition, PDE5 down‐regulation may lead to the decreased efficacy of PDE5 inhibitors in some hypertensive ED patients and treatment of oxidative stress could be used as a new therapeutic target for this type of ED.
Convergence in sympatry: Evolution of blue‐banded wing pattern in Morpho butterflies
Authors: Llaurens Violaine , Le Poul Yann , Puissant Agathe , Blandin Patrick , Debat Vincent
Published: October 2020

Species interactions such as mimicry can promote trait convergence but disentangling this effect from those of shared ecology, evolutionary history, and niche conservatism is often challenging. Here by focusing on wing colour pattern variation within and between three butterfly species living in sympatry in a large proportion of their range, we tested the effect of species interactions on trait diversification. These butterflies display a conspicuous iridescent blue coloration on the dorsal side of their wings and a cryptic brownish colour on the ventral side. Combined with an erratic and fast flight, these colour patterns increase the difficulty of capture by predators and contribute to the high escape abilities of these butterflies. We hypothesize that, beyond their direct contribution to predator escape, these wing patterns can be used as signals of escape abilities by predators, resulting in positive frequency‐dependent selection favouring convergence in wing pattern in sympatry. To test this hypothesis, we quantified dorsal wing pattern variations of 723 butterflies from the three species sampled throughout their distribution, including sympatric and allopatric situations and compared the phenotypic distances between species, sex and localities. We detected a significant effect of localities on colour pattern, and higher inter‐specific resemblance in sympatry as compared to allopatry, consistent with the hypothesis of local convergence of wing patterns. Our results provide support to the existence of escape mimicry in the wild and stress the importance of estimating trait variation within species to understand trait variation between species, and to a larger extent, trait diversification at the macro‐evolutionary scale.
Lysophosphatidic acid induces thrombospondin‐1 production in primary cultured rat cortical astrocytes
Authors: Hisaoka‐Nakashima Kazue , Yokoe Toshiki , Watanabe Shintaro , Nakamura Yoki , Kajitani Naoto , Okada‐Tsuchioka Mami , Takebayashi Minoru , Nakata Yoshihiro , Morioka Norimitsu
Published: October 2020

Lysophosphatidic acid (LPA), a brain membrane‐derived lipid mediator, plays important roles including neural development, function, and behavior. In the present study, the effects of LPA on astrocyte‐derived synaptogenesis factor thrombospondins (TSPs) production were examined by real‐time PCR and western blotting, and the mechanism underlying this event was examined by pharmacological approaches in primary cultured rat cortical astrocytes. Treatment of astrocytes with LPA increased TSP‐1 mRNA, and TSP‐2 mRNA, but not TSP‐4 mRNA expression. TSP‐1 protein expression and release were also increased by LPA. LPA‐induced TSP‐1 production were inhibited by AM966 a LPA1 receptor antagonist, and Ki16425, LPA1/3 receptors antagonist, but not by H2L5146303, LPA2 receptor antagonist. Pertussis toxin, Gi/o inhibitor, but not YM‐254890, Gq inhibitor, and NF499, Gs inhibitor, inhibited LPA‐induced TSP‐1 production, indicating that LPA increases TSP‐1 production through Gi/o‐coupled LPA1 and LPA3 receptors. LPA treatment increased phosphorylation of extracellular signal‐regulated kinase (ERK), p38 mitogen‐activated protein kinase (MAPK), and c‐Jun N‐terminal kinase (JNK). LPA‐induced TSP‐1 mRNA expression was inhibited by U0126, MAPK/ERK kinase (MEK) inhibitor, but not SB202190, p38 MAPK inhibitor, or SP600125, JNK inhibitor. However, LPA‐induced TSP‐1 protein expression was diminished with inhibition of all three MAPKs, indicating that these signaling molecules are involved in TSP‐1 protein production. Treatment with antidepressants, which bind to astrocytic LPA1 receptors, increased TSP‐1 mRNA and protein production. The current findings show that LPA/LPA1/3 receptors signaling increases TSP‐1 production in astrocytes, which could be important in the pathogenesis of affective disorders and could potentially be a target for the treatment of affective disorders.

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24S‐hydroxycholesterol: Cellular effects and variations in brain diseases
Authors: Sodero Alejandro O.
Published: October 2020

The adult brain exhibits a characteristic cholesterol homeostasis, with low synthesis rate and active catabolism. Brain cholesterol turnover is possible thanks to the action of the enzyme cytochrome P450 46A1 (CYP46A1) or 24‐cholesterol hydroxylase, that transforms cholesterol into 24S‐hydroxycholesterol (24S‐HC). But before crossing the blood–brain barrier (BBB), this oxysterol, that is the most abundant in the brain, can act locally, affecting the functioning of neurons, astrocytes, oligodendrocytes, and vascular cells. The first part of this review addresses different aspects of 24S‐HC production and elimination from the brain. The second part concentrates in the effects of 24S‐HC at the cellular level, describing how this oxysterol affects cell viability, amyloid β production, neurotransmission, and transcriptional activity. Finally, the role of 24S‐HC in Alzheimer, Huntington and Parkinson diseases, multiple sclerosis and amyotrophic lateral sclerosis, as well as the possibility of using this oxysterol as predictive and/or evolution biomarker in different brain disorders is discussed.

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Infarct Growth despite Endovascular Thrombectomy Recanalization in Large Vessel Occlusive Stroke
Authors: Regenhardt Robert W. , Etherton Mark R. , Das Alvin S. , Schirmer Markus D. , Hirsch Joshua A. , Stapleton Christopher J. , Patel Aman B. , Leslie‐Mazwi Thabele M. , Rost Natalia S.
Published: October 2020

BACKGROUND AND PURPOSE

Endovascular thrombectomy (EVT) has revolutionized large vessel occlusion stroke care. However, not all patients with good endovascular results achieve good outcomes. We sought to understand the clinical significance of magnetic resonance imaging defined infarct growth despite adequate reperfusion and identify associated clinical and radiographic variables.

METHODS

History, presentation, treatments, and outcomes for consecutive EVT patients at a referral center were collected. Adequate reperfusion was defined as thrombolysis in cerebral infarction (TICI) score 2b‐3. Region‐specific infarct volumes in white matter, cortex, and basal ganglia were determined on diffusion‐weighted imaging. Infarct growth was defined as post‐EVT minus pre‐EVT volume. Good outcome was defined as 90‐day modified Rankin Scale ≤2.

RESULTS

Forty‐four patients with adequate reperfusion were identified with median age 72 years; 64% were women. Each region showed infarct growth: white matter (median pre‐EVT 7 cubic centimeters [cc], post‐EVT 16 cc), cortex (4 cc, 15 cc), basal ganglia (2 cc, 4 cc), total (20 cc, 39 cc). In multivariable regression, total infarct growth independently decreased the odds of good outcome (odds ratio = .946, 95% CI = .897, .998). Further multivariable analyses for determinants of infarct growth identified female sex was associated with less total growth (β = −.294, P = .042), TICI 3 was associated with less white matter growth (β = −.277, P = .048) and cortical growth (β = −.335, P = .017), and both female sex (β = −.332, P = .015) and coronary disease (β = −.337, P = .015) were associated with less cortical growth.

CONCLUSIONS

Infarct growth occurred despite adequate reperfusion, disproportionately in the cortex, and independently decreased the odds of good outcome. Infarct growth occurred while patients were hospitalized and may represent a therapeutic target. Potential determinants of region‐specific infarct growth were identified that require confirmation in larger studies.
To live with a Schizoaffective disorder
Authors: Arndtzén Mats , Sandlund Mikael
Published: October 2020

This article tells about how it is to live with severe mental illness, but primarily it is a story about how to recover with the help of mental health professionals, friends and medication. The overarching aim is to convey a message of hope. Even great difficulties may be left behind. As a summary, four key points for staff members to reflect on are mentioned: Nurses should often encourage their patients and acknowledge their progress; Nurses should remember that there is hope, for everybody; Nurses should be encouraged to use their creativity when working with patients; If the alliance between nurse and patient is working well in a bilateral sense, nurses should have the opportunity to keep in touch with the patient as long as the patient needs and benefits from it.
Comparison of child self‐report and parent proxy‐report of symptoms: Results from a longitudinal symptom assessment study of children with advanced cancer
Authors: Montgomery Kathleen E. , Vos Kaylee , Raybin Jennifer L. , Ward Jessica , Balian Chelsea , Gilger Elizabeth A. , Li Zhanhai
Published: October 2020

Purpose

This report represents a subanalysis of data from a primary study and addresses a gap in understanding the similarities and differences of symptom reporting between children with advanced cancer and their parents. The objectives of this subanalysis were to (1) compare reports of symptom prevalence, symptom burden, and symptom frequency, severity, and distress between groups of children and adolescents and their parents, and (2) describe concordance of symptom reports within individual child–parent dyads.

Design and Methods

Forty‐six children with relapsed, refractory, or progressive cancer and their parents from five pediatric cancer centers prospectively reported symptoms every 2 weeks for up to 61 weeks. The abbreviated Pediatric Quality of Life and Evaluation of Symptoms Technology—Memorial Symptom Assessment Scales were used to measure symptom prevalence, frequency, severity, and distress.

Results

Children and parents reported pain, fatigue, nausea, and sleeping difficulties as the most frequently occurring symptoms. With the exception of shortness of breath, parents reported symptom prevalence more often than children. The differences in parent reports were statistically significant for fatigue, nausea, lack of appetite, feeling nervous, and sadness. Parents reported higher symptom burden scores compared to children for all individual symptoms except shortness of breath. Children reported higher scores for 19 of 32 possible symptom frequency, severity, and distress ratings. Children's scores were higher for frequency and severity, while parents’ scores were higher for distress. Sleeping difficulties, pain, nausea, and diarrhea demonstrated the highest concordance, while feeling nervous, sadness, irritability, and fatigue yielded the lowest concordance between children's and parents’ symptom reports.

Practice Implications

Eliciting the symptom experience from the child, when appropriate, rather than a parent proxy is best practice given evidence supporting the overestimation of symptom prevalence by parents and underestimation of symptom frequency and severity for some symptoms. When proxy raters must be used, pediatric nurses should educate proxy raters regarding symptom assessment, and assess and tend to symptoms that may not exhibit visual cues. Pediatric nurses should conduct a comprehensive symptom assessment and evaluate beyond the presence of symptoms and include an assessment of frequency, severity, and distress for physical and psychological symptoms to optimize symptom management strategies.
Cognitive and Institutional Determinants of Public Policy Changes: A Comparative Analysis of Brazil and Chile
Authors: Muñoz del Campo Norma , de Souza Rocha Lukic Melina
Published: October 2020

Esta investigación tiene como objetivo conectar las teorías cognitivas e institucionales para explicar cómo evolucionan las políticas públicas. Partiendo de los límites identificados en el modelo propuesto por los enfoques cognitivos, el artículo muestra que este marco puede complementarse con el modelo de cambio institucional propuesto por las teorías del institucionalismo histórico. Este estudio se centra de esta manera en la dinámica del cambio y propone ir más allá de las teorías fundamentadas en coyunturas críticas o choques exógenos que se basan más en las continuidades que en los cambios. Se abordan aquí dos estudios de caso sobre el cambio de políticas públicas—la política fiscal en Brasil y las políticas medioambientales en Chile. Sugerimos un modelo que puede explicar los cambios cognitivos graduales al proponer dos formas diferentes de cambio de política—anclaje ideacional y estratificación cognitiva.
An agent‐based model determining a successful reintroduction of the extinct passenger pigeon
Authors: Elzinga David C. , Boggess Erin , Collignon Jordan , Riederer Alanna , Capaldi Alex
Published: October 2020

The passenger pigeon (Ectopistes migratorius) was an iconic species in eastern North America that was one of the most numerous birds in the world at the time of European colonization. Passenger pigeons went extinct in 1914 due to excessive hunting. Current research aims to de‐extinct the passenger pigeon and someday release the species into its historic range. To determine under which conditions a passenger pigeon colony could survive a reintroduction into a natural habitat, we developed an agent‐based model to simulate the population dynamics of the passenger pigeon in a number of present‐day forest environments. The model incorporates the following stochastic processes: resource distribution, reproduction, and natural death. Bioenergetics, forest composition, and other ecological values were obtained from literature. Our simulation results suggest that passenger pigeons could survive a reintroduction into a modern natural environment, but their survival can be optimized with certain release dates, sex ratios, and forest composition.

Recommendations for Resource Managers

Genome engineering advancements suggest that the de‐extinction of passenger pigeons is feasible; however, the ability for passenger pigeons to live in the modern forest composition of their old habitat remains unexplored. Our model suggests the following regarding reintroduction strategies:

A successful reintroduction of passenger pigeons is plausible, but sensitive to the strategy selected. Moderate deviations from optimal reintroduction strategies can greatly diminish the probability of a successful reintroduction.

The optimal successful reintroduction strategy has an equal number of male and female passenger pigeons released in a dense oak‐hickory forest at the peak of the forest's masting cycle.

Beyond persistence, the population growth of passenger pigeons within 10 years is at best, limited. Efforts to monitor and protect passenger pigeons during the transient phase of their reintroduction is critical.
Safety of electronic massagers in patients with cardiac implantable electronic devices
Authors: Chia Pow‐Li , Mok Kwang‐How , Wong Shiun Woei , Foo David
Published: October 2020

Background

Current recommendations by cardiac implantable electronic devices (CIEDs) manufacturers on electromagnetic interference (EMI) are based on extrapolations of studies exposing CIEDs to electromagnetic fields produced by Helmholtz coils and industrial equipment. There are currently little data whether commercially available electronic massagers can cause EMI in CIEDs in vivo. This is of interest as the use of electronic massagers is common in Asia.

Methods

The study evaluated CIED patients before, during and after a 10‐minute exposure to a commercially available electronic backrest upper body massager. Post‐exposure sensing, pacing threshold, and lead impedance were compared to baseline values. The presence of artefacts, EMI, and adverse clinical events during exposure was recorded.

Results

Eighty‐six patients (59 pacemakers and 27 implantable cardioverter‐defibrillators) with a total of 151 leads (60 atrial, 86 right ventricular, and 5 left ventricular) were evaluated. There was no incidence of EMI causing inappropriate inhibition of pacing or inappropriate defibrillation. There was no significant difference in the pacing threshold, sensing, and lead impedance post‐exposure compared to baseline values.

Conclusion

Our study, though limited by small numbers and exposure to only 1 type of electronic massager, shows that it is potentially safe for patients with CIEDs to use commercially available electronic massagers with similar characteristics as the one tested in this study.
Restoration of rapids habitat in a Great Lakes connecting channel, the St. Marys River, Michigan
Authors: Molina‐Moctezuma Alejandro , Ellis Eric , Kapuscinski Kevin L. , Roseman Edward F. , Heatlie Terry , Moerke Ashley
Published: October 2020

Aquatic habitat has been extensively altered throughout the Laurentian Great Lakes to increase navigation connectivity. In particular, the St. Marys River, a Great Lakes connecting channel, lost >50% of its historic rapids habitat over the past century. In 2016, the natural flow was restored to the Little Rapids area of the St. Marys River. The goal of our study was to evaluate physical and ecological responses to the restoration of the Little Rapids area. Extensive habitat and biological data were collected prior to restoration (2013 and 2014), and after restoration (2017 and 2018). Measured parameters included total suspended solids, current velocity, benthic macroinvertebrates, and larval, juvenile, and adult fishes. Total suspended solids stayed low (<4 mg/L) following restoration, with the exception of a single construction‐related event. Pre‐restoration data indicated that all measured velocities were below the target flow rate of 0.24 m/s, whereas 70% of the measured habitat was above the target flow post‐restoration. Abundance and richness of benthic macroinvertebrates were reduced following restoration (>90% reduction). We observed a 45% increase in richness of larval fish 2 years after restoration and a 131% increase in catch per unit effort. For adult fishes, the proportion of individuals with a preference for fast‐moving waters increased from 1.5 to 45% in the restored area, and from 7 to 15% upstream of the restored area; a similar response was observed for lithophilic spawners. The physical and biological conditions of the Little Rapids improved and resembled conditions typical of rapids habitat extent in other areas of the river and other systems.
Sharp estimate of electric field from a conductive rod and application
Authors: Fang Xiaoping , Deng Youjun , Liu Hongyu
Published: October 2020

We are concerned with the quantitative study of the electric field perturbation due to the presence of an inhomogeneous conductive rod embedded in a homogenous conductivity. We sharply quantify the dependence of the perturbed electric field on the geometry of the conductive rod. In particular, we accurately characterize the localization of the gradient field (i.e., the electric current) near the boundary of the rod where the curvature is sufficiently large. We develop layer‐potential techniques in deriving the quantitative estimates and the major difficulty comes from the anisotropic geometry of the rod. The result complements and sharpens several existing studies in the literature. It also generates an interesting application in EIT (electrical impedance tomography) in determining the conductive rod by a single measurement, which is also known as the Calderón's inverse inclusion problem in the literature.
Mechanism of fibrosis and stricture formation in Crohn's disease
Authors: Alfredsson Johannes , Wick Mary Jo
Published: October 2020

Crohn's disease (CD) is a chronic inflammatory disease of the gastrointestinal tract that leads to substantial suffering for millions of patients. In some patients, the chronic inflammation leads to remodelling of the extracellular matrix and fibrosis. Fibrosis, in combination with expansion of smooth muscle layers, leaves the bowel segment narrowed and stiff resulting in strictures, which often require urgent medical intervention. Although stricture development is associated with inflammation in the affected segment, anti‐inflammatory therapies fall far short of treating strictures. At best, current therapies might allow some patients to avoid surgery in a shorter perspective and no anti‐fibrotic therapy is yet available. This likely relates to our poor understanding of the mechanism underlying stricture development. Chronic inflammation is a prerequisite, but progression to strictures involves changes in fibroblasts, myofibroblasts and smooth muscle cells in a poorly understood interplay with immune cells and environmental cues. Much of the experimental evidence available is from animal models, cell lines or non‐strictured patient tissue. Accordingly, these limitations create the basis for many previously published reviews covering the topic. Although this information has contributed to the understanding of fibrotic mechanisms in general, in the end, data must be validated in strictured tissue from patients. As stricture formation is a serious complication of CD, we endeavoured to summarize findings exclusively performed using strictured tissue from patients. Here, we give an update of the mechanism driving this serious complication in patients, and how the strictured tissue differs from adjacent unaffected tissue and controls.
Refractory thrombotic thrombocytopenic purpura related to checkpoint inhibitor immunotherapy
Authors: Lancelot Moira , Miller Maureen J. , Roback John , Stowell Sean R.
Published: October 2020

Background

Checkpoint inhibitors enhance T‐lymphocyte–mediated antitumor responses, resulting in increased survival for patients with neoplastic disease. However, a subset of patients receiving checkpoint inhibitor therapy may experience adverse complications that include the development of autoimmune conditions, such as thrombotic thrombocytopenic purpura (TTP). Given the potential etiologic differences of checkpoint inhibitor–related autoimmunity, TTP that develops in the presence of checkpoint inhibitors may be refractory to current treatment methods and therefore may require additional treatment and prognostic consideration.

Case Report

Herein, we describe the unique clinical course of a patient who was treated with the combined checkpoint inhibitors nivolumab and ipilimumab for Stage IV malignant melanoma, who subsequently developed TTP. Unlike many patients with TTP, this patient failed to develop a sustained response to therapeutic plasma exchange. Additional use of steroids, anti‐CD20, and plasma cell–targeting therapy (bortezomib) also failed to substantially reverse thrombocytopenia in a sustainable fashion. During this time, her melanoma progressed, and she ultimately succumbed.

Conclusion

This case illustrates not only that TTP may be a potential complication of checkpoint inhibitor therapy, but also that TTP developing in this setting may result in an unpredictable response to commonly employed TTP treatment modalities. Ultimately, checkpoint inhibitor–related TTP may require distinct management approaches and prognostic considerations.
Oxygen transport and utilisation during exercise in cystic fibrosis: contributors to exercise intolerance
Authors: Saynor Zoe L. , Gruet Mathieu , Rodriguez‐Miguelez Paula , Harris Ryan A.
Published: October 2020

New Findings

What is the topic of this review?

This review highlights the central and peripheral mechanisms that alter oxygen transport and utilisation and thereby contribute to exercise limitation in people with cystic fibrosis, considering also viable therapeutic targets for intervention.

What advances does it highlight?

Although traditionally considered a respiratory condition, pathological intramuscular and cardiovascular changes in people with cystic fibrosis appear to be key determinants of exercise intolerance up until the later stages of respiratory disease. Even young, habitually active patients with normal lung function experience multisystemic abnormalities, which play a role in exercise intolerance.

Cystic fibrosis (CF) is a complex condition, commonly associated with exercise limitation. The mechanisms responsible for this in CF are of interest, given that lower aerobic fitness is associated with an increased risk of being hospitalised with pulmonary exacerbation, a poorer quality of life and a poorer prognosis. Pathophysiological changes in lung function are considered central to CF, and may contribute to exercise limitation. However, it is now clear that the pathogenesis of exercise limitation in this population is multifactorial, with alterations in cardiovascular, muscle and pulmonary function contributing. Whilst some of these changes are attributable to respiratory disease per se, the CF transmembrane conductance regulator protein is also found in skeletal muscle and the vascular endothelium and can directly alter central and localised oxygen delivery, as well as the ability to effectively extract and utilise oxygen at the myocyte level. Since intense exercise poses considerable challenges to arterial oxygen content and/or blood flow and its supply to the working skeletal muscle, evaluating the exercise physiology of people with CF has helped us understand the mechanisms underlying exercise intolerance. Through several investigations over recent years, we have collectively demonstrated that people with CF exhibit reduced skeletal muscle oxygen extraction and utilisation during exercise, with a lesser contribution from haemodynamic or chronotropic mechanisms. Taken together, our findings highlight the importance of targeting mechanisms of skeletal muscle oxygen utilisation in CF to improve exercise tolerance and we offer potential therapeutic interventional strategies.
Passive Aligning of Ribbon Cable in Sliding Surface Gripper for Assembly Task
Authors: Yi June-Sup , Yumbla Francisco , Auh Eugene , Abayebas Meseret , Luong Tuan Anh , Moon Hyungpil
Published: October 2020

A passive aligning strategy for the assembly task of a ribbon cable is presented using a sliding surface gripper. Once the gripper grasps the ribbon cable, the sliding surface of the gripper pulls the cable in one direction, and at the end of the pulling process, the box-shaped structure of the fingertip of the gripper passively aligns the cable to a predictable pose. The relationship between the alignment speed of the cable on the sliding surface and the grasping force was modeled and verified by experiments. The maximum position error of the ribbon cable connector aligned by the proposed method was 0.7 mm, which was smaller than the mating tolerance between typical male and female connectors. The mating of the connectors was successfully conducted with an industrial robot whose repeatability is less than a millimeter. The entire assembly process of ribbon cable connectors, including visual recognition of the ribbon cable pose, grasping and aligning of the ribbon cable, and mating a pair of cable connectors, was successfully implemented.
REEF3D Wave Generation Interface for Commercial Computational Fluid Dynamics Codes
Authors: Pakozdi Csaba , Bihs Hans , Kamath Arun
Published: October 2020

In recent years, computational fluid dynamics (CFD) developments have shown a trend to combine Reynolds-averaged Navier–Stokes (RANS) CFD simulation with other methods such as wave theories or velocity potential-based numerical wave tanks, in order to reduce to computation costs. This is however not a new approach, and there exists a large amount of literature about domain decomposition techniques describing a two way coupling between the RANS CFD models and other methods. One can also observe an increasing popularity in the use of a less sophisticated technique where different fluid solvers are combined with one-way coupling. In these methods, a predefined solution is provided in the far-field, while a three-dimensional (3D) CFD simulation is applied in a limited zone near the structure. The predefined solution is used to specify the background far-field solution. The published solutions use wave theory or a numerical wave tank where the predefined solution is calculated parallel to the RANS solver. In this way, it is possible to reduce the interpolation inaccuracy and the amount of transferred data to the CFD simulation. The disadvantage of this technique is that the far field solver has to be prepared in order to run in parallel with the CFD solver. Due to the one way coupling, it is possible to predefine this information in tables before the CFD simulation. This technique makes it possible to define a general interface between difference solvers without modifying existing codes. This paper presents such a technique where the predefined solution is stored into files.
Thermosolutal Marangoni Impact on Bioconvection in Suspension of Gyrotactic Microorganisms Over an Inclined Stretching Sheet
Authors: Kairi Rishi Raj , Shaw Sachin , Roy Subrata , Raut Santanu
Published: October 2020

Microorganism cells movement in the fluid is universal and affects many ecological and biological processes, including infection, reproduction, and marine life ecosystem. There are many biological and medical applications that require an understanding of the transport process in nanofluids containing a suspension of microorganism. The present problem deals with the bioconvection of Casson nanofluid containing a suspension of motile gyrotactic microorganisms over an inclined stretching sheet in the presence of thermal radiation, viscous dissipation, and chemical reaction and magnetic field. At the surface, the influence of the thermosolutal Marangoni convection and suction/injection impact are considered. The governing equations are solved numerically by using fourth-order Runge–Kutta–Fehlberg method with shooting technique. The impact of the major pertinent parameters on the velocity, temperature, nanoparticles concentration, and density of the motile microorganism is illustrated graphically. Finally, the correlations of various crucial parameters on skin friction, local Nusselt number, Sherwood number, and local motile microorganism density number are displayed through the graphs and tables.
A Data-Driven Machining Error Analysis Method for Finish Machining of Assembly Interfaces of Large-Scale Components
Authors: Fan Wei , Zheng Lianyu , Ji Wei , Xu Xun , Wang Lihui , Zhao Xiong
Published: October 2020

To guarantee the final assembly quality of the large-scale components, the assembly interfaces of large components need to be finish-machined on site. Such assembly interfaces are often in low-stiffness structure and made of difficult-to-cut materials, which makes it hard to fulfill machining tolerance. To solve this issue, a data-driven adaptive machining error analysis and compensation method is proposed based on on-machine measurement. Within this context, an initial definite plane is fitted via an improved robust iterating least-squares plane-fitting method based on the spatial statistical analysis result of machining errors of the key measurement points. Then, the parameters of the definite plane are solved by a simulated annealing-particle swarm optimization (SA-PSO) algorithm to determine the optimal definite plane; it effectively decomposes the machining error into systematic error and process error. To reduce these errors, compensation methods, tool-path adjustment method, and an optimized group of cutting parameters are proposed. The proposed method is validated by a set of cutting tests of an assembly interface of a large-scale aircraft vertical tail. The results indicate that the machining errors are successfully separated, and each type of error has been reduced by the proposed method. A 0.017 mm machining accuracy of the wall-thickness of the assembly interface has been achieved, well fulfilling the requirement of 0.05 mm tolerance.