bluuebunny/crossref_metadata_2025 huggingface dataset:
Human placenta mesenchymal stem cell-derived exosomes delay H2O2-induced aging in mouse cholangioids
Authors: Chen Wenyi , Zhu Jiaqi , Lin Feiyan , Xu Yanping , Feng Bing , Feng Xudong , Sheng Xinyu , Shi Xiaowei , Pan Qiaoling , Yang Jinfeng , Yu Jiong , Li Lanjuan , Cao Hongcui
Published: March 2021

Background

Cholangiocyte senescence is an important pathological process in diseases such as primary sclerosing cholangitis (PSC) and primary biliary cirrhosis (PBC). Stem cell/induced pluripotent stem cell-derived exosomes have shown anti-senescence effects in various diseases. We applied novel organoid culture technology to establish and characterize cholangiocyte organoids (cholangioids) with oxidative stress-induced senescence and then investigated whether human placenta mesenchymal stem cell (hPMSC)-derived exosomes exerted a protective effect in senescent cholangioids.

Methods

We identified the growth characteristics of cholangioids by light microscopy and confocal microscopy. Exosomes were introduced concurrently with H2O2 into the cholangioids. Using immunohistochemistry and immunofluorescence staining analyses, we assessed the expression patterns of the senescence markers p16INK4a, p21WAF1/Cip1, and senescence-associated β-galactosidase (SA-β-gal) and then characterized the mRNA and protein expression levels of chemokines and senescence-associated secretory phenotype (SASP) components.

Results

Well-established cholangioids expressed cholangiocyte-specific markers. Oxidative stress-induced senescence enhanced the expression of the senescence-associated proteins p16INK4a, p21WAF1/Cip1, and SA-β-gal in senescent cholangioids compared with the control group. Treatment with hPMSC-derived exosomes delayed the cholangioid aging progress and reduced the levels of SASP components (i.e., interleukin-6 and chemokine CC ligand 2).

Conclusions

Senescent organoids are a potential novel model for better understanding senescence progression in cholangiocytes. hPMSC-derived exosomes exert protective effects against senescent cholangioids under oxidative stress-induced injury by delaying aging and reducing SASP components, which might have therapeutic potential for PSC or PBC.
Cell specific quantitative iron mapping on brain slices by immuno-µPIXE in healthy elderly and Parkinson’s disease
Authors: Friedrich I. , Reimann K. , Jankuhn S. , Kirilina E. , Stieler J. , Sonntag M. , Meijer J. , Weiskopf N. , Reinert T. , Arendt T. , Morawski M.
Published: March 2021

Iron is essential for neurons and glial cells, playing key roles in neurotransmitter synthesis, energy production and myelination. In contrast, high concentrations of free iron can be detrimental and contribute to neurodegeneration, through promotion of oxidative stress. Particularly in Parkinson’s disease (PD) changes in iron concentrations in the substantia nigra (SN) was suggested to play a key role in degeneration of dopaminergic neurons in nigrosome 1. However, the cellular iron pathways and the mechanisms of the pathogenic role of iron in PD are not well understood, mainly due to the lack of quantitative analytical techniques for iron quantification with subcellular resolution. Here, we quantified cellular iron concentrations and subcellular iron distributions in dopaminergic neurons and different types of glial cells in the SN both in brains of PD patients and in non-neurodegenerative control brains (Co). To this end, we combined spatially resolved quantitative element mapping usingmicroparticleinducedX-rayemission (µPIXE) with nickel-enhanced immunocytochemical detection of cell type-specific antigens allowing to allocate element-related signals to specific cell types. Distinct patterns of iron accumulation were observed across different cell populations. In the control (Co) SNc, oligodendroglial and astroglial cells hold the highest cellular iron concentration whereas in PD, the iron concentration was increased in most cell types in the substantia nigra except for astroglial cells and ferritin-positive oligodendroglial cells. While iron levels in astroglial cells remain unchanged, ferritin in oligodendroglial cells seems to be depleted by almost half in PD. The highest cellular iron levels in neurons were located in the cytoplasm, which might increase the source of non-chelated Fe3+, implicating a critical increase in the labile iron pool. Indeed, neuromelanin is characterised by a significantly higher loading of iron including most probable the occupancy of low-affinity iron binding sites. Quantitative trace element analysis is essential to characterise iron in oxidative processes in PD. The quantification of iron provides deeper insights into changes of cellular iron levels in PD and may contribute to the research in iron-chelating disease-modifying drugs.
The descriptive epidemiology of brand-specific gun ownership in the US: results from the 2019 National Lawful Use of Guns Survey
Authors: Siegel Michael , Dunn Devon , Shareef Faizah , Neufeld Miriam , Boine Claire
Published: March 2021

Background

No previous study has identified the specific brands of guns owned by gun owners. This study aimed to: (1) ascertain and describe patterns of brand- and model-specific gun ownership among US gun owners; and (2) investigate the relationship between gun owners’ brand and model preferences and their attitudes towards common firearm violence prevention policies.

Methods

Using a national, pre-recruited internet panel of US adults in 2019, we surveyed gun owners (N = 2086) to ascertain their opinions regarding firearm violence prevention policies and to assess the brands and models of guns that they owned.

Results

Brand-specific gun ownership was highly concentrated and was dominated by three pistol brands, two revolver brands, three rifle brands, and three shotgun brands. There was wide variation in policy attitudes among owners of different gun brands, but little variation across owners of different gun types (i.e., pistols, rifles, revolvers, shotguns). We were able to identify the specific gun models owned by 1218 (59.4%) of the gun owners. Based on the classification of these gun models into three types we categorized the gun ownership pattern of the sample as 33.4% recreational, 45.5% self-defense, and 21.1% tactical. There were marked differences in support for firearm-related policies among the three groups, with support generally highest among the Recreation group and lowest among the Tactical group.

Conclusion

We conclude that gun brands and models are strong predictors of a gun owner’s attitudes regarding firearm-related policies. This information could help public health practitioners develop segment-specific communications that will appeal to each group in order to more effectively engage gun owners in firearm violence prevention.
Patterns of alcohol and drug utilization in trauma patients during the COVID-19 pandemic at six trauma centers
Authors: McGraw Constance , Salottolo Kristin , Carrick Matthew , Lieser Mark , Madayag Robert , Berg Gina , Banton Kaysie , Hamilton David , Bar-Or David
Published: March 2021

Background

Since the national stay-at-home order for COVID-19 was implemented, clinicians and public health authorities worldwide have expressed growing concern about the potential repercussions of drug and alcohol use due to social restrictions. We explored the impact of the national stay-at-home orders on alcohol or drug use and screenings among trauma admissions.

Methods

This was a retrospective cohort study at six Level I trauma centers across four states. Patients admitted during the period after the onset of the COVID-19 restrictions (defined as March 16, 2020-May 31, 2020) were compared with those admitted during the same time period in 2019. We compared 1) rate of urine drug screens and blood alcohol screens; 2) rate of positivity for drugs or alcohol (blood alcohol concentration ≥ 10 mg/dL); 3) characteristics of patients who were positive for drug or alcohol, by period using chi-squared tests or Fisher’s exact tests, as appropriate. Two-tailed tests with an alpha of p < 0.05 was used on all tests.

Results

There were 4762 trauma admissions across the study period; 2602 (55%) in 2019 and 2160 (45%) in 2020. From 2019 to 2020, there were statistically significant increases in alcohol screens (34% vs. 37%, p = 0.03) and drug screens (21% vs. 26%, p < 0.001). Overall, the rate of alcohol positive patients significantly increased from 2019 to 2020 (32% vs. 39%, p = 0.007), while the rate of drug positive patients was unchanged (57% vs. 52%, p = 0.13). Of the 1025 (22%) patients who were positive for alcohol or drugs, there were significant increases in a history of alcoholism (41% vs. 26%, p < 0.001), and substance abuse (11% vs. 23%, p < 0.001) in the 2020 period. No other statistically significant differences were identified among alcohol or drug positive patients during COVID-19 compared to the same period in 2019.

Conclusions

Our first wave of COVID-19 data suggests that trauma centers were admitting significantly more patients who were alcohol positive, as well those with substance use disorders, potentially due to the impact of social restrictions and guidelines. Further longitudinal research is warranted to assess the alcohol and drug positive rates of trauma patients over the COVID-19 pandemic.
Two epochal turns of inequality, their significance, and their dynamics
Authors: Therborn Göran
Published: March 2021

At the end of the twentieth century, two historical turns of economic inequality happened. Among the developed countries of the Global North, the secular trend of decreasing intra-national inequality turned into its opposite. At about the same time, the long period of global inequality began to bend down, among households as well as among nations, a turn less noticed but more significant than the reduction of extreme poverty in the South. The foundation of the former turn was the beginning of de-industrialization in the North, and the coming of a post-industrial society, very different from the one predicted. The paper analyzes the trigger of the turn and the central dynamics of the new inequality in the rich North, financialization, and the digital revolution. It then tries to answer two questions about the global turn: Was the decline of global inequality causally connected to the increase of Northern intra-national inequality? Will there be a development of industrial societies in the South? The answer to both is no. What lies ahead is more likely a global convergence of intra-national unequalization, albeit with both different and similar dynamics, as the decline of extreme poverty in the South is leading to inequality increases comparable to those of the North. Post-industrialism has no egalitarian dialectic like that of industrial capitalism, but the dynamics of the twenty-first century inequality are likely to be confronted not only with popular protest movements but also with an emergent scholarly and intellectual Egalitarian Enlightenment.
How do borders influence migration? Insights from open and closed border regimes in the three Guianas
Authors: Vezzoli Simona
Published: March 2021

The ways border regimes affect migration patterns remain ambiguous. Closed borders may constrain migration but also encourage migrants to pursue alternative migration channels and destinations. While open borders may be associated with higher migration, oftentimes they promote circulation and return. To clarify how different border regimes influence migration patterns, this article examines the impact of open and closed border regimes on migration outcomes in Guyana, Suriname and French Guiana in the 1950s–1980s period, when all three gained independence or non-sovereign status and colonial ties were strong. The article proposes a conceptual schematic model that can accommodate varied post-colonial political and border regime transitions and explains changes in the timing, destination and composition of migration. The analysis finds that, counterintuitively, closed borders can lead to high emigration while open borders can encourage people to stay. The proposed model also illustrates the relevance of three dimensions of time: thehistorical juncture, thesequence of changeand thetime span. In sum, rather than preventing migration, border regimes yield important effects that lead to migration diversification.
How migrants manifest their transnational identity through online social networks: comparative findings from a case of Koreans in Germany
Authors: Park Sunyoung , Gerrits Lasse
Published: March 2021

Although migration has long been an imperative topic in social sciences, there are still needs of study on migrants’ unique and dynamic transnational identity, which heavily influences the social integration in the host society. In Online Social Network (OSN), where the contemporary migrants actively communicate and share their stories the most, different challenges against migrants’ belonging and identity and how they cope or reconcile may evidently exist. This paper aims to scrutinise how migrants are manifesting their belonging and identity via different technological types of online social networks, to understand the relations between online social networks and migrants’ multi-faceted transnational identity. The research introduces a comparative case study on an online social movement led by Koreans in Germany via their online communities, triggered by a German TV advertisement considered as stereotyping East Asians given by white supremacy’s point of view. Starting with virtual ethnography on three OSNs representing each of internet generations (Web 1.0 ~ Web 3.0), two-step Qualitative Data Analysis is carried out to examine how Korean migrants manifest their belonging and identity via their views on “who we are” and “who are others”. The analysis reveals how Korean migrants’ transnational identities differ by their expectation on the audience and the members in each online social network, which indicates that the distinctive features of the online platform may encourage or discourage them in shaping transnational identity as a group identity. The paper concludes with the two main emphases: first, current OSNs comprising different generational technologies play a significant role in understanding the migrants’ dynamic social values, and particularly, transnational identities. Second, the dynamics of migrants’ transnational identity engages diverse social and situational contexts. (keywords: transnational identity, migrants’ online social networks, stereotyping migrants, technological evolution of online social network).
Tracheoinnominate fistula: acute bleeding and hypovolemic shock due to a trachea-innominate artery fistula after long-term tracheostomy, treated with a stent-graft
Authors: Khanafer Ali , Hellstern Victoria , Meißner Helfried , Harmening Christoph , Schneider Klaus , Henkes Hans
Published: March 2021

Background

A tracheo-innominate fistula is a rare but life-threatening complication of tracheostomy and has a mortality rate of 100% without therapy. The underlying cause is an acquired fistula between the brachiocephalic trunk and the trachea, induced by a tracheostomy cannula’s mechanical impact.

Case presentation

A 25-year-old female was admitted with pulsatile bleeding from a tracheostomy. The cause of the bleeding was a tracheo-innominate artery fistula, which was difficult to recognize. Said fistula was treated with implantation of a self-expanding stent-graft. The bleeding stopped immediately after the implantation of the stent-graft. Dual antiplatelet medication with aspirin IV and ticagrelor PO, bridged with a bolus of eptifibatide IV, was started right after the stent deployment.

Conclusions

Endovascular self-expanding stent-graft implantation is a viable treatment option for tracheo-innominate artery fistulae, especially in hemorrhagic emergencies.
A narrative review of the ethnomedicinal usage of Cannabis sativa Linnaeus as traditional phytomedicine by folk medicine practitioners of Bangladesh
Authors: Shakil Shahriar S. M. , Gowan Matt , Hughes Kerry , Azam Md. Nur Kabidul , Ahmed Md. Nasir
Published: March 2021

Background

There is a worldwide interest in the use of Cannabis sativa for biomedicine purposes. Cannabis has ethnomedicinal usage as a natural medicine in Bangladesh and cultivated during the British Empire period for revenues.

Objective

Folk medicine practitioners (FMPs) from different districts of Bangladesh have been using Cannabis sativa, but until now there have not been any compiled studies particularly regarding this practice. Hence, this review is an effort to retrieve the traditional usage of Cannabis sativa as a phytomedicine from published ethnomedicinal studies.

Methods and materials

Information was searched by using the search terms “ethnomedicinal Cannabis sativa and Bangladesh”; “Bangladesh cannabaceae and ethnomedicinal survey”; “ganja, bhang and folk medicine Bangladesh”; “tetrahydrocannabinol (THC), cannabinoid and therapeutic, clinical trial”; and “cannabis and pharmacological/biological” and retrieved from ethnobotanical articles available on PubMed, Scopus, Science Direct, and Google Scholar databases. A search of the relevant scientific literature also was conducted to assess the efficacy of the ethnomedicinal usage of Cannabis sativa.

Results

While reviewing over 200 ethnomedicinal plants’ survey articles, we found that FMPs of Bangladesh from 12 different districts used Cannabis sativa to treat cited ailments like sleep-associated problems (n=5), neuropsychiatric and CNS problems (n=5), and infections and respiratory problems (n=5) followed by rheumatism, gastrointestinal, gynecological (n=4 each), cancer, sexual, and other ailments including hypertension, headache, itch, increases bile secretion, abortifacient, dandruff, fever, and urinary problems (n=1 each). There are a total of 15 formulations identified from the 11 out of 18 ethnomedicinal plant survey reports. The leaf was the main plant part used (53.8%), followed by root (23%), seed (7.7%) and flower, inflorescence, resin, and all parts 3.8% respectively.

Conclusions

Sales and cultivation of Cannabis are illegal at present in Bangladesh, but the use of Cannabis sativa as a natural phytomedicine has been practiced traditionally by folk medicine practitioners of Bangladesh for many years and validated through relevant pharmacological justification. Although Cannabis sativa possesses ethnomedicinal properties in the folk medicine of Bangladesh, it is, furthermore, needed to conduct biological research to consolidate pharmacological justification about the prospects and challenges of Cannabis and cannabinoids’ use in Bangladesh as safer biomedicine in the future.
Risk assessment and the adsorptive removal of some pesticides from synthetic wastewater: a review
Authors: Garba Zaharaddeen N. , Abdullahi Amina K. , Haruna Abdurrashid , Gana Sa’adatu A.
Published: March 2021

Background

The need for environmental protection and remediation processes has been an increasing global concern. Pesticides are used as biological agents, disinfectants, antimicrobials, and also in a mixture of some chemical substances. Their modes of application are through selective dispensing and attenuation processes which act upon any pest that compete with the production, processing, and storage of foods and also in agricultural commodes. The pests might comprise weeds, insects, birds, fish, and microbes.

Main body

Pesticides are commonly found in water surface, landfill leachate, ground water, and wastewater as pollutant. An overview of recently studied adsorption processes for the pesticide elimination from polluted water has been reported in this study utilizing activated carbon, clay materials, biomass materials, metal organic frame work, graphene, and carbon-based materials as well as agricultural wastes as adsorbents. The risk assessment and cost analysis of adsorbents were also provided.

Conclusion

Evidences from literature recommend modified adsorbent and composite materials to have a prospective use in pesticide removal from wastewater. The adsorption data obtained fitted into different isotherm and kinetic models and also the thermodynamic aspect have been discussed.

Graphical abstract
High flow nasal cannula oxygen and non-invasive mechanical ventilation in management of COVID-19 patients with acute respiratory failure: a retrospective observational study
Authors: Shoukri Amr Mounir
Published: March 2021

Background

High flow nasal cannula oxygen (HFNCO) is a relatively new technique used to deliver oxygen in respiratory failure patients. This retrospective study is aiming to assess the role and benefits of using HFNCO compared to non-invasive ventilation (NIV) in management of patients with acute hypoxemic respiratory failure associated with coronavirus disease 2019 (COVID-19).

Results

A retrospective analysis of the files of 63 patients with COVID-19 and acute hypoxemic respiratory failure admitted to the intensive care unit (ICU), 37 patients received HFNCO as initial therapy, and 26 patients were primarily treated with NIV. There was no significant difference between the 2 groups in terms of baseline characteristics, laboratory tests, arterial blood gases, PaO2/FiO2 values, and vital signs. Re-assessment after 24 h of starting treatment with either HFNCO or NIV showed significant improvement (P<0.01) in the respiratory rate, heart rate, and oxygenation parameters. The magnitude of improvement of the vital signs and oxygenation was not significantly different between patients using HFNCO or NIV. Success rate of HFNCO was 86.4%, endotracheal intubation with invasive mechanical ventilation was required in 10.81% of patients, and mortality rate was 2.7%. Success rate of NIV was 84.6%, endotracheal intubation rate was 11.53%, and mortality rate was 3.8%. No significant difference (P>0.05) between the 2 groups as regards the duration of treatment, rate of endotracheal intubation with invasive mechanical ventilation, and mortality rate.

Conclusion

High flow nasal cannula oxygen (HFNCO) is effective in the management of acute hypoxemic respiratory failure associated with COVID-19. Its efficacy is similar to NIV, with no difference in the duration of treatment, endotracheal intubation rate, or mortality rate.
Settler Colonial Studies and/as the Transnational Western
Authors: Young Alex Trimble
Published: March 2021

The article explores contemporary debates regarding the representation of Indigenous resistance in the field of settler colonial studies by putting the work of Australian theorist Patrick Wolfe into conversation with the political allegories articulated in two contemporary Western films. Its first section, tracing what Wolfe called his “pharmacological indebtedness” to Gayatri Spivak, considers the methodological problems for settler colonial studies that have emerged from Wolfe’s critique of the settler intellectual’s representation of Indigenous resistance. The second section suggests an alternative direction for transnational settler colonial studies by undertaking a comparative reading of two films—Hell or High Water (2016) written by US settler filmmaker Taylor Sheridan, and Goldstone (2016) written and directed by Indigenous Australian (Gamilaroi) director Ivan Sen. Both films collapse the detective genre with settler colonialism’s most recognizable representational genre: the Western. In so doing, they articulate narratives about the ongoing crimes of settler colonialism that offer novel perspectives on the question of what is knowable—and by whom—under settler colonialism’s structure of violence.
From Violence as Anti-Politics to Politics as Anti-Violence
Authors: Balibar Étienne
Published: March 2021

This article discusses violence in its intrinsic relationship to politics. This conjunction of politics and violence is not just a special feature of our historical experience; rather it can never be separated from it, albeit with distinct forms and to different degrees. Starting from situations embodying extreme violence, or cruelty, and contrasting them with a politics of civility, this article argues that if we want to define the conditions and the goals of politics, it is not enough to just be mindful of violence, or to see it as a central problem for politics. What we need is a new foundation for politics, arising from the consideration of extreme violence. Extreme violence, therefore, is not one question among others for politics; it is the question where the possibility or impossibility of politics is at stake.
Ηγεσία και διοίκηση της εκπαίδευσης, το παράδειγμα των διευθυντών σχολικών μονάδων πρωτοβάθμιας εκπαίδευσης, από το 1974 έως και το 2016
Authors: Παπαθανασίου Ευαγγελία
Published: March 2021

Η διατριβή πραγματεύεται μέσα από τη θεωρητική, ιστορική - ερμηνευτική έρευνα με τη βοήθεια της σχετικής νομοθεσίας και αντίστοιχης βιβλιογραφίας, την ανάδειξη διοικητικών στελεχών της εκπαίδευσης και συγκεκριμένα των διευθυντών σχολικών μονάδων από το 1974 έως και το 2016, η οποία χαρακτηρίστηκε από την εντονότερη παραγωγή εκπαιδευτικής νομοθεσίας έως τότε. Οι μεταρρυθμίσεις που έκανε η εκάστοτε κυβέρνηση της χώρας με συγκεκριμένα κάθε φορά ταυτοτικά χαρακτηριστικά στο χώρο της παιδείας αποτελούσαν το μέσο εφαρμογής της πολιτικής της και συνακόλουθα τη συντήρηση και αναπαραγωγή ή την αλλαγή του κοινωνικού συστήματος. Τα εκπαιδευτικά μοντέλα που προέκυψαν ως αποτέλεσμα αυτών των μεταρρυθμίσεων ανέδειξαν τη σημασία και την αξία του ρόλου και των καθηκόντων των διευθυντών στην πρωτοβάθμια εκπαίδευση, καθώς και την ανάγκη προσαρμογής στα δεδομένα κάθε περιόδου και στα πλαίσια της Ευρωπαϊκής Ένωσης. Η διερεύνηση και η ερμηνεία των μοντέλων ηγεσίας σε συνάρτηση με τη διοίκηση και την οργάνωση της δημόσιας εκπαίδευσης μας απασχολούν ιδιαίτερα καθώς αποτελούν αναγκαία συνθήκη για την οργανωτική αποτελεσματικότητα, μιας και η καταλληλότητα ενός διευθυντή - ηγέτη και οι πρακτικές εφαρμογής του επηρεάζουν καταλυτικά την καθημερινή λειτουργία του σχολείου. H σύνδεση των νόμων και των μοντέλων ηγεσίας, διοίκησης και οργάνωσης μέσω της ποιοτικής ανάλυσης και συγκριτικής αποτίμησης των αλλαγών και των μεταρρυθμίσεων στη χώρα μας βρίσκεται σε απόλυτη συνάρτηση και συσχέτιση με την επιλογή και τις κρίσεις, το ρόλο και τα καθήκοντα των διευθυντών των σχολικών μονάδων στην πρωτοβάθμια εκπαίδευση. Εντοπίζουμε μεταξύ άλλων τις δυσκολίες και τα προβλήματα που προκύπτουν από το παραδοσιακό, συγκεντρωτικό διοικητικό μοντέλο στο ελληνικό σχολείο ακόμα και σήμερα, με αποτέλεσμα την ενίσχυση της γραφειοκρατίας και το περιορισμένο μέτριο έργο της διοίκησης. Σε μια σχολική πραγματικότητα που η ανάγκη για εμφάνιση νέων προτύπων διαχείρισης, οργάνωσης και διοίκησης είναι επιτακτικότερη από ποτέ, αναζητάμε σύγχρονα πρότυπα στα οποία ο διευθυντής θα μπορούσε να λειτουργεί ως δημοκρατικός, μετασχηματιστικός, συμμετοχικός ηγέτης της σχολικής πραγματικότητας και ως το πρόσωπο εκείνο που θα καθοδηγεί και θα ενεργοποιεί τους συναδέλφους του, θα τους εμπνέει σε νέους ρόλους και θα συμβάλει σε ένα δημοκρατικότερο περιβάλλον και σε μια διοίκηση ολικής ποιότητας.
Pulsed laser induced doping of two-dimensional crystals
Authors: Δεμερίδου Ιωάννα
Published: March 2021

Τα διδιάστατα διχαλκογενή μέταλλα μετάπτωσης έχουν προσελκύσει παγκόσμιο ενδιαφέρον τις τελευταίες δεκαετίες ύστερα από την επιτυχημένη απομόνωση του γραφενίου. Τα διχαλκογενή μέταλλα μετάπτωσης είναι ημιαγωγοί και διαθέτουν μοναδικές οπτοηλεκτρονικές ιδιότητες λόγω της υπέρλεπτης φύσης τους. Καθώς ο αριθμός των στρωμάτων τους μειώνεται, μετατρέπονται από ημιαγωγό έμμεσου ενεργειακού χάσματος σε ημιαγωγό άμεσου ενεργειακού χάσματος. Στην παρούσα διδακτορική διατριβή μελετώνται οι οπτικές ιδιότητες του μονοστρωματικού κρυστάλλου δισουλφίδιο βολφραμίου, μέλος της οικογένειας των διχαλκογενών μετάλλων μετάπτωσης, και την επίδραση του φωτοχημικού εμπλουτισμού με τη χρήση υπεριώδους παλμικού λέιζερ. Προτείνεται μια καινοτόμα μέθοδος εμπλουτισμού, η οποία μπορεί να ελέγξει την πυκνότητα ηλεκτρονίων στο μονοστρωματικό κρύσταλλο δισουλφίδιου βολφραμίου (1L-WS2). Ο φωτοχημικός εμπλουτισμός σε περιβάλλον χλωρίου με τη χρήση υπεριώδους παλμικού λέιζερ αποδείχθηκε πως είναι μια μέθοδος που παρέχει έλεγχο της συγκέντρωσης φορέων στο μονοστρωματικό κρύσταλλο WS2. Η συστηματική μετατόπιση κορυφής του ουδέτερου εξιτονίου προς μικρότερες τιμές ενέργειας στα φάσματα φωτοφωτάγειας είναι ένδειξη της μείωσης της συγκέντρωσης των ηλεκτρονίων στον κρύσταλλο και η ικανότητα του σταδιακού ελέγχου της πυκνότητας των φορέων με το χρόνο έκθεσης σε περιβάλλον χλωρίου. Η μετατόπιση του επιπέδου ενέργειας Fermi συνδέεται με τον έλεγχο της πυκνότητας ηλεκτρονίων λόγω του χλωρίου. Το φαινόμενο του φωτοχημικού εμπλουτισμού μπορεί να αντιστραφεί ύστερα από σάρωση της επιφάνειας του μονοστρωματικού κρυστάλλου με συνεχές λέιζερ σε περιβάλλον ατμόσφαιρας. Ο αμφίδρομος έλεγχος του επιπέδου Fermi σε συνδυασμό με την ικανότητα προεπιλεγμένης περιοχής του κρυστάλλου με τη χρήση του λέιζερ προσφέρει χωρικά ελεγχόμενο εμπλουτισμό σε κλίμακα μικρομέτρων. Αυτή η διαδικασία ενίσχυσε το ενδιαφέρον για τον έλεγχο της εκπομπής κυκλικά πολωμένου φωτός στις ζώνες του φωτοχημικά εμπλουτισμένου κρυστάλλου. Τα διχαλκογενή μέταλλα μετάπτωσης έχουν ενδιαφέρουσες ιδιότητες που αφορούν τη ζώνη και το σπιν των φορέων του υλικού λόγω της ισχυρής αλληλεπίδρασης τους. Αποδεικνύουμε τον έλεγχο της πόλωσης σπιν/ζώνης κατά 40% σε μονοστρωματικό κρύσταλλο WS2 ύστερα από το φωτοχημικό εμπλουτισμό. Η μείωση της κυκλικής πόλωσης μετά από το φωτοχημικό εμπλουτισμό σε περιβάλλον χλωρίου αποδίδεται στη μείωση των ελαττωμάτων του κρυσταλλικού πλέγματος καθώς επίσης και την αύξηση του χρόνου ζωής των εξιτονίων που δεν εκπέμπουν φωτόνια. Οι θεωρητικές προβλέψεις και οι μετρήσεις φασματοσκοπίας μεταβατικής απορρόφησης επιβεβαιώνουν τα αποτελέσματα μας. Επιπλέον αποδείξαμε πως ο βαθμός της κυκλικής πόλωσης εξαρτάται από τον τύπο υποστρώματος στον οποίο εναποτίθεται ο μονοστρωματικός κρύσταλλος αλλά και από τον φωτοχημικό εμπλουτισμό. Αυτά τα συμπεράσματα καθιστούν τα διχαλκογενή μέταλλα μετάπτωσης κατάλληλα υλικά για μελλοντικές εφαρμογές και αρχιτεκτονικές υπολογιστών.
Stress Management Interventions at the Organizational Level in Customs
Authors: Trubicyn K. , Kalmykova O.
Published: March 2021

It is urgent to develop a complex of primary, secondary and tertiary interventions for stress management, taking into account the specifics of both the models of labor and organiza-tional culture and regulatory recommendations for the implementation of personnel and educa-tional activities in the customs authority. The subject of this study is the methods of stress man-agement interventions at the organizational level in the customs authorities. The work implements diagnostic tools: the McLean Organizational Stress Scale test, the “Coping behavior in stressful situations CISS” technique.
La heterogeneidad sintagmática de los adverbios en español
Authors: Jiménez Juliá Tomás
Published: March 2021

La heterogeneidad sintagmática de los adverbios en español

El adverbio ha sido desde las primeras descripciones gramaticales por parte de los estoicos una clase heterogénea, que recogía todo lo que no era nombre, verbo o partícula. Ello ha hecho que dentro de esta clase de palabra se encuentren unidades sintagmáticamente muy diferentes, tanto unidades léxicamente plenas y expandibles como otras sin posibilidad de expansión y con contextos fijados. La presente contribución propone posibles criterios sintagmáticos con el fin de ordenar el campo de esta clase de palabra de manera similar a como se ordenan otras clases de palabras léxicas.
Optimization: From Its Inception
Authors: Magnanti Thomas L.
Published: March 2021

Optimization has been one of the most fundamental and extensive contributions of management science/operations research, with an enormous number of contributions and subfields developed by many researchers and practitioners. When the journal Management Science launched in 1954, little was known about optimization, including some results in nonlinear optimization and the simplex method and duality developed for linear programming. However, linear programming computations were limited to problems with at most 101 linear constraints. Then some early contributions by seminal researchers began to develop foundations for the field. I will review a few of these early contributions, focusing on the traveling sales problem and integer programming, decomposition, and column generation. I will summarize some research and applied contributions since then, including the enormous development of computations. I will focus on linear and integer programs with some material on combinatorial optimization.

This paper was accepted by David Simchi-Levi, Special Section of Management Science: 65th Anniversary.
Optimal Control of Partially Observable Semi-Markovian Failing Systems: An Analysis Using a Phase Methodology
Authors: Khaleghei Akram , Kim Michael Jong
Published: March 2021

In “Optimal Control of Partially Observable Semi-Markovian Failing Systems: An Analysis using a Phase Methodology,” Khaleghei and Kim study a maintenance control problem a as partially observable semi-Markov decision process (POSMDP), a problem class that is typically computationally intractable and not amenable to structural analysis. The authors develop a new approach based on a phase methodology where the idea is to view the intractable POSMDP as the limiting problem of a sequence of tractable POMDPs. They show that the optimal control policy can be represented as a control limit policy which monitors the estimated conditional reliability at each decision epoch, and, by exploiting this structure, an efficient computational approach to solve for the optimal control limit and corresponding optimal value is developed.
Agricultural Roots and Subnational Cultural Heterogeneity in Domestic Acquisitions
Authors: Wang Hao , Zeng Yuping , Shenkar Oded
Published: March 2021

Drawing on the novel-to-the-field rice theory, we study how subnational cultural heterogeneity impacts target performance improvement following an acquisition. Data from domestic acquisitions in the Chinese beer industry show performance is significantly impacted by cultural characteristics formulated through agricultural subsistence activities. We find that both cultural similarity and dissimilarity influence performance: (1) in transactions in which both the acquirer and target are located in rice culture regions, targets achieve greater performance improvement than in those in which both firms are located in a wheat culture region, and (2) targets located in wheat culture areas bought by acquirers from a rice culture area gain greater performance improvement than rice culture targets acquired by firms from a wheat culture area. We also find that acquirers’ experience with rice targets is less beneficial than their experience with wheat targets.
Targeted vs opportunistic screening for viral hepatitis among UK migrant communities: a cost-effectiveness analysis
Authors: Salmon Harold A , Briscoe Simon , Foster Graham R , Pitt Martin A
Published: March 2021

Worldwide eradication of chronic hepatitis B and C viruses by 2030 is a stated goal of the World Health Organization, UK government and the European Union. This study investigated the cost-effectiveness of targeted screening vs opportunistic screening for hepatitis B and C among migrant populations in the UK. Results of a previous clinical trial (HepFREE) carried out in London and Bradford were used to develop a combined decision tree and Markov simulation model. Despite a low response to invitations for vaccination, and a heterogeneous level of response between communities of different ethnic composition, this analysis shows that incentivised targeted screening is cost-effective at willingness-to-pay thresholds over £8540 per incremental quality-adjusted life year over a lifetime. Furthermore, probabilistic analysis of input parameter uncertainty suggests that the intervention has a greater than 95% probability of being cost-effective at willingness-to-pay thresholds under £30 000 per incremental quality-adjusted life year. These results strongly suggest that targeted screening should play a key part in the eradication of the hepatitis B and C viruses.
Optimising referral pathways for patients with non-alcoholic fatty liver disease in the UK
Authors: Boyd Alexander , Srivastava Ankur , Rosenberg William , Newsome Philip N , Armstrong Matthew J
Published: March 2021

The increasing burden of non-alcoholic fatty liver disease means that robust clinical pathways need to be established in primary care to identify patients with advanced fibrosis who may benefit from specialist management. This article summarises the current landscape of non-invasive liver fibrosis tests and discusses the outcomes and lessons learned from non-alcoholic fatty liver disease pathways that have been instigated around the UK. The inherent challenges of implementing such pathways are explored, along with developing technologies, such as artificial intelligence blood testing, which will likely play an important role in helping to identify and risk-stratify more patients with non-alcoholic fatty liver disease in primary care in the future.
Stable evanescent wave mode-locked laser based on a photonic-crystal-fiber-induced Mach–Zehnder filter as a gain-tilt equalizer
Authors: Ridha Fay F. , Salman Ansam M. , Al-Janabi Abdulhadi
Published: March 2021

In this paper, a switchable multichannel ytterbium-doped fiber laser based on a Mach–Zehnder interferometer (MZI) has been experimentally demonstrated. The MZI is fabricated by splicing a short piece of nonlinear photonic-crystal fiber (NLPCF) between two segments of a single-mode fiber. MZI-based NLPCF gathering with the intracavity birefringence polarization controller offers functions as both the selective comb filter and the mode locker. The laser can emit a single, dual, triple, or quadruple channel that can be varied in the spectral span around1030–1050 nm by only adjusting the pump power or polarization state. A stable evanescent wave, picosecond mode-locking generation with variable repetition rate (24.5 to 18.23 MHz and 34.64 MHz) has been realized via only inserting the polarization controller and adjusting its state inside the cavity. To the best of the authors’ knowledge, this the first demonstration of a passive filter based on a NLPCF-MZ interferometer to generate switchable mode-locked pulses delivered from a single laser oscillator.
High-accuracy longitudinal position measurement using self-accelerating light
Authors: Prabhakar Shashi , Plachta Stephen Z. D. , Ornigotti Marco , Fickler Robert
Published: March 2021

Radially self-accelerating light exhibits an intensity pattern that describes a spiraling trajectory around the optical axis as the beam propagates. In this article, we show in simulation and experiment how such beams can be used to perform a high-accuracy distance measurement with respect to a reference using simple off-axis intensity detection. We demonstrate that generating beams whose intensity pattern simultaneously spirals with fast and slow rotation components enables a distance measurement with high accuracy over a broad range, using the high and low rotation frequency, respectively. In our experiment, we achieve an accuracy of around 2 µm over a longitudinal range of more than 2 mm using a single beam and only two quadrant detectors. Because our method relies on single-beam interference and only requires a static generation and simple intensity measurements, it is intrinsically stable and could find applications in high-speed measurements of longitudinal position.
Laser-assisted etching of borosilicate glass in potassium hydroxide
Authors: Bischof David , Kahl Michael , Michler Markus
Published: March 2021

We present a method for the selective etching of borosilicate glass (SCHOTT Borofloat 33), in which we modify the glass with an ultrashort pulse laser and subsequent wet chemical etching. The BF33 glass is often used in microtechnology to produce sensors, actors, and fluidic chips as it can be bonded to silicon wafers by anodic bonding. The glass is irradiated and modified by circular polarized laser light with a wavelength of 1030 nm. By etching the glass with potassium hydroxide, the modified material can be removed. In this study, the selectivity was analyzed dependent on the laser parameters pulse repetition rate, pulse duration, writing speeds, and pulse energy. A selectivity up to 540 could be observed in this study. Finally, the manufacturing capabilities for three-dimensional free form shapes in BF33 are demonstrated and compared with fused silica.
Theoretical study on residual infrared absorption of Ti:sapphire laser crystals
Authors: Gong Qiaorui , Zhao Chengchun , Yang Yilun , Fang Qiannan , Li Shanming , Xu Min , Hang Yin
Published: March 2021

Residual infrared absorption is a key problem affecting the laser emission efficiency of Ti:sapphire crystal. In this paper, the origin of residual infrared absorption of Ti:sapphire crystal is systematically studied by using the first principles method. According to the contact conditions of O octahedron in the crystal structure of

Al

2

O

3

, four

Ti

3
+

−

Ti

3
+

ion pair models and three

Ti

4
+

−

Ti

3
+

ion pair models were defined and constructed. For what we believe is the first time, the near-infrared absorption spectra consistent with the experimental results were obtained in specific theoretical models. The electronic structures, absorption spectra, and charge distributions calculated show that the line-contact

Ti

3
+

−

Ti

3
+

ion pair with antiferromagnetic coupling and the face-contact

Ti

4
+

−

Ti

3
+

ion pair are two main contributors to the residual infrared absorption of Ti:sapphire, while some other ion pair models provide a basis to explain more complex residual infrared absorption.
Demonstrating the utility of flexible sequence queries against indexed short reads with FlexTyper
Authors: Richmond Phillip Andrew , Kaye Alice Mary , Kounkou Godfrain Jacques , Av-Shalom Tamar Vered , Wasserman Wyeth W.
Published: March 2021

Across the life sciences, processing next generation sequencing data commonly relies upon a computationally expensive process where reads are mapped onto a reference sequence. Prior to such processing, however, there is a vast amount of information that can be ascertained from the reads, potentially obviating the need for processing, or allowing optimized mapping approaches to be deployed. Here, we present a method termed FlexTyper which facilitates a “reverse mapping” approach in which high throughput sequence queries, in the form of k-mer searches, are run against indexed short-read datasets in order to extract useful information. This reverse mapping approach enables the rapid counting of target sequences of interest. We demonstrate FlexTyper’s utility for recovering depth of coverage, and accurate genotyping of SNP sites across the human genome. We show that genotyping unmapped reads can correctly inform a sample’s population, sex, and relatedness in a family setting. Detection of pathogen sequences within RNA-seq data was sensitive and accurate, performing comparably to existing methods, but with increased flexibility. We present two examples of ways in which this flexibility allows the analysis of genome features not well-represented in a linear reference. First, we analyze contigs from African genome sequencing studies, showing how they distribute across families from three distinct populations. Second, we show how gene-marking k-mers for the killer immune receptor locus allow allele detection in a region that is challenging for standard read mapping pipelines. The future adoption of the reverse mapping approach represented by FlexTyper will be enabled by more efficient methods for FM-index generation and biology-informed collections of reference queries. In the long-term, selection of population-specific references or weighting of edges in pan-population reference genome graphs will be possible using the FlexTyper approach. FlexTyper is available at https://github.com/wassermanlab/OpenFlexTyper.
Discovery of novel dual adenosine A1/A2A receptor antagonists using deep learning, pharmacophore modeling and molecular docking
Authors: Wang Mukuo , Hou Shujing , Wei Yu , Li Dongmei , Lin Jianping
Published: March 2021

Adenosine receptors (ARs) have been demonstrated to be potential therapeutic targets against Parkinson’s disease (PD). In the present study, we describe a multistage virtual screening approach that identifies dual adenosine A1 and A2A receptor antagonists using deep learning, pharmacophore models, and molecular docking methods. Nineteen hits from the ChemDiv library containing 1,178,506 compounds were selected and further tested by in vitro assays (cAMP functional assay and radioligand binding assay); of these hits, two compounds (C8 and C9) with 1,2,4-triazole scaffolds possessing the most potent binding affinity and antagonistic activity for A1/A2A ARs at the nanomolar level (pKi of 7.16–7.49 and pIC50 of 6.31–6.78) were identified. Further molecular dynamics (MD) simulations suggested similarly strong binding interactions of the complexes between the A1/A2A ARs and two compounds (C8 and C9). Notably, the 1,2,4-triazole derivatives (compounds C8 and C9) were identified as the most potent dual A1/A2A AR antagonists in our study and could serve as a basis for further development. The effective multistage screening approach developed in this study can be utilized to identify potent ligands for other drug targets.
A stacked ensemble method for forecasting influenza-like illness visit volumes at emergency departments
Authors: Novaes de Amorim Arthur , Deardon Rob , Saini Vineet
Published: March 2021

Accurate and reliable short-term forecasts of influenza-like illness (ILI) visit volumes at emergency departments can improve staffing and resource allocation decisions within hospitals. In this paper, we developed a stacked ensemble model that averages the predictions from various competing methodologies in the current frontier for ILI-related forecasts. We also constructed a back-of-the-envelope prediction interval for the stacked ensemble, which provides a conservative characterization of the uncertainty in the stacked ensemble predictions. We assessed the accuracy and reliability of our model with 1 to 4 weeks ahead forecast targets using real-time hospital-level data on weekly ILI visit volumes during the 2012-2018 flu seasons in the Alberta Children’s Hospital, located in Calgary, Alberta, Canada. Our results suggest the forecasting performance of the stacked ensemble meets or exceeds the performance of the individual models over all forecast targets.