bluuebunny/crossref_metadata_2025 huggingface dataset:
Der AKTIN-Monatsbericht: Plädoyer für ein standardisiertes Reporting in der Notaufnahme
Authors: Greiner Felix , Erdmann Bernadett , Thiemann Volker S. , Baacke Markus , Grashey Rupert , Habbinga Kirsten , Kombeiz Alexander , Majeed Raphael W. , Otto Ronny , Wedler Katrin , Brammen Dominik , Walcher Felix
Published: June 2021

Hintergrund

Vor dem Hintergrund der steigenden Inanspruchnahme und aktuellen Veränderungen in der Notfallversorgung ist eine standardisierte Erfassung relevanter Kennzahlen in Notaufnahmen zwingend erforderlich.

Ziel der Arbeit

Es werden die Konsentierung von Inhalten und technische Umsetzung eines automatisierten Reportings für Notaufnahmen des AKTIN-Notaufnahmeregisters beschrieben. Ziel war ein aussagefähiger Monatsbericht zur Prozesssteuerung und Qualitätssicherung.

Material und Methoden

Datengrundlage ist der Datensatz Notaufnahme V2015.1 der Deutschen Interdisziplinären Vereinigung für Intensiv- und Notfallmedizin e. V. (DIVI). Die Konsentierung der Inhalte erfolgte auf Basis von externen Referenzen und fachlicher Expertise; die technische Entwicklung erfolgte anhand eines Testdatensatzes. Mit der Software R und Apache Formatting Objects Processor (FOP) wird der finale Bericht im PDF-Format automatisiert erstellt.

Ergebnisse

Der Bericht enthält unter anderem Angaben zu Fallzahlen, Demografie der Patienten, Vorstellungsgründen, Ersteinschätzung, Verbleib und ausgewählten Prozesszeiten in Form von Tabellen und Grafiken. Er wird monatsweise automatisch oder auf Anforderung aus den Routinedaten generiert. Fehlende Werte und Ausreißer werden zur Abschätzung der Datenqualität separat ausgewiesen.

Diskussion

Beim AKTIN-Monatsbericht handelt es sich um ein Instrument, welches das Versorgungsgeschehen aufbereitet und visualisiert. Die konsentierten Kennzahlen sind praxistauglich und bilden auch die Vorgaben des Gemeinsamen Bundesausschusses zur Ersteinschätzung ab. Die Nutzung von Interoperabilitätsstandards erlaubt eine automatische Erfassung im Alltag, gewährleistet eine Unabhängigkeit von einzelnen IT-Systemen und kann als Grundlage für ein klinikübergreifendes Benchmarking dienen.
Long-term outcome and quality of life after CNS cavernoma resection: eloquent vs. non-eloquent areas
Authors: Shoubash Loay , Baldauf Jörg , Matthes Marc , Kirsch Michael , Rath Matthias , Felbor Ute , Schroeder Henry W. S.
Published: June 2021

The aim of this study is to analyze the long-term quality of life after surgery of cavernoma. A monocentric retrospective study was conducted on 69 patients with cavernoma treated microsurgically between 2000 and 2016. The eloquence was adopted from Spetzler-Martin definition. A most recent follow-up was elicited between 2017 and 2019, in which the quality of life (QoL) was evaluated with the Short Form-12 questionnaire (SF12). Forty-one lesions were in eloquent group (EG), 22 in non-eloquent group (NEG), 3 in orbit, and 3 in the spinal cord. Postoperative worsening of the modified Rankin scale (mRS) occurred in 19.5% of cases in EG versus 4.5% in NEG. After a mean follow-up of 6.5 years (SD 4.6), the neurological status was better or unchanged compared to baseline in 85.4% of EG and 100% of NEG. Regarding QoL assessment of 44 patients (EG n = 27, NEG n = 14) attended the last follow-up. Patients after eloquent cavernoma resection reported a non-inferior QoL in most SF12 domains (except for physical role) compared to NEG. However, they reported general health perception inferior to norms, which was affected by the limited physical and emotional roles. At a late follow-up, the surgical morbidity was transient in the NEG and mostly recovered in the EG. The QoL comparison between eloquent and non-eloquent cavernomas created interesting and new data after prolonged follow-up. These results add value for decision-making as well as patient counseling for future encountered cases. Preoperative evaluation of QoL is recommended for future studies to assess QoL dynamics.
Motion correction of free-breathing magnetic resonance renography using model-driven registration
Authors: Flouri Dimitra , Lesnic Daniel , Chrysochou Constantina , Parikh Jehill , Thelwall Peter , Sheerin Neil , Kalra Philip A. , Buckley David L. , Sourbron Steven P.
Published: June 2021

Introduction

Model-driven registration (MDR) is a general approach to remove patient motion in quantitative imaging. In this study, we investigate whether MDR can effectively correct the motion in free-breathing MR renography (MRR).

Materials and methods

MDR was generalised to linear tracer-kinetic models and implemented using 2D or 3D free-form deformations (FFD) with multi-resolution and gradient descent optimization. MDR was evaluated using a kidney-mimicking digital reference object (DRO) and free-breathing patient data acquired at high temporal resolution in multi-slice 2D (5 patients) and 3D acquisitions (8 patients). Registration accuracy was assessed using comparison to ground truth DRO, calculating the Hausdorff distance (HD) between ground truth masks with segmentations and visual evaluation of dynamic images, signal-time courses and parametric maps (all data).

Results

DRO data showed that the bias and precision of parameter maps after MDR are indistinguishable from motion-free data. MDR led to reduction in HD (HDunregistered = 9.98 ± 9.76, HDregistered = 1.63 ± 0.49). Visual inspection showed that MDR effectively removed motion effects in the dynamic data, leading to a clear improvement in anatomical delineation on parametric maps and a reduction in motion-induced oscillations on signal-time courses.

Discussion

MDR provides effective motion correction of MRR in synthetic and patient data. Future work is needed to compare the performance against other more established methods.
Robotic versus laparoscopic splenectomy: a systematic review of perioperative outcomes
Authors: Bhat Anantha Shreepad , Farrugia Alexia , Muhammad Qazi Rahim , Kulikova Viera , Marangoni Gabriele , Ahmad Jawad
Published: June 2021

Background

Elective splenectomy has various indications and can be performed open or minimally invasively. Laparoscopic splenectomy (LS) is popular but has limitations. Some studies suggest potential superiority of robotic splenectomy (RS) over LS. As such, we conducted a systematic review to determine whether RS has greater positive perioperative outcomes in comparison to LS in the adult population.

Methods

We searched for studies that reported perioperative outcomes and compared RS to LS in the adult population. Outcome measures were operative time, conversion to open surgery, postoperative complications, mortality, length of stay, blood loss and cost analysis. A simple, unpaired two-tailed student’s t‑test was used to compare outcomes between the RS and LS patient groups.

Results

After full-text analysis of 47 papers, three studies met the inclusion criteria. The studies involved 72 patients (28 in the RS group, 44 in the LS group). RS demonstrated no significantly reduced blood loss in comparison to LS (p = 0.13). RS had no cases converting to open surgery and no postoperative complications in comparison to LS. No significant difference was found between RS and LS with regards to LOS (p = 0.89) and cost benefit (p = 0.74). RS had a higher operative time in comparison to LS which was not statistically significant (p = 0.45).

Conclusion

The RS approach may be associated with lower blood loss and a lower risk of conversions. There was no statistical difference between RS and LS with regards to length of stay (LOS) and cost. RS takes longer to perform in comparison to LS.
Generalized threshold secret sharing and finite geometry
Authors: Ligeti Peter , Sziklai Peter , Takáts Marcella
Published: June 2021

In the history of secret sharing schemes many constructions are based on geometric objects. In this paper we investigate generalizations of threshold schemes and related finite geometric structures. In particular, we analyse compartmented and hierarchical schemes, and deduce some more general results, especially bounds for special arcs and novel constructions for conjunctive 2-level and 3-level hierarchical schemes.
Safety, pharmacokinetics, and preliminary efficacy of the PARP inhibitor talazoparib in Japanese patients with advanced solid tumors: phase 1 study
Authors: Naito Yoichi , Kuboki Yasutoshi , Ikeda Masafumi , Harano Kenichi , Matsubara Nobuaki , Toyoizumi Shigeyuki , Mori Yuko , Hori Natsuki , Nagasawa Takashi , Kogawa Takahiro
Published: June 2021

Background: Talazoparib is a poly(ADP-ribose) polymerase enzyme inhibitor. This open-label, non-randomized, phase 1 study of talazoparib investigated the safety, pharmacokinetics, and preliminary antitumor activity in Japanese patients with locally advanced or metastatic solid tumors, regardless of mutations in DNA damage repair-related genes, who are resistant to/ineligible for standard therapies. Methods: Patients received talazoparib dosed orally at 0.75 or 1 mg once daily using a modified 3 + 3 dose-escalation scheme. Primary endpoint was dose-limiting toxicities during the first cycle of talazoparib. Results: Nine patients (median age 62.0 years) were included: 3 and 6 patients at the 0.75 and 1.0 mg once-daily dose levels, respectively. No dose-limiting toxicities were reported. The most commonly reported treatment-emergent adverse events (≥2 patients) were anemia, stomatitis, maculopapular rash, platelet count decreased, neutrophil count decreased, and alanine aminotransferase increased. Three patients had grade ≥ 3 treatment-emergent adverse events (anemia, brain metastases [1 patient each], and neutrophil and white blood cell count decreased [same patient]). Two patients temporarily discontinued treatment due to a treatment-emergent adverse event, and 1 patient required a dose reduction for neutrophil count decreased (all at 1 mg once daily). Talazoparib exposure (Cmax and AUC) after single and multiple dosing was slightly higher proportionally with talazoparib 1 mg than talazoparib 0.75 mg. The overall disease control rate was 44.4%, including 2 patients with stable disease. The recommended phase 2 dose of talazoparib was established as 1 mg once daily. Conclusions: Single-agent talazoparib was well tolerated and had preliminary antitumor activity in Japanese patients with advanced solid tumors. ClinicalTrials.gov identifier: NCT03343054 (November 17, 2017).
A review about methods for supporting failure risks analysis in eco-assessment
Authors: Spreafico Christian
Published: June 2021

This paper critically reviewed 106 scientific papers proposing methods to enrich eco-assessment with failure determination and risk assessment. The provided research perspective is new and significantly different from the reviews in the literature which are mostly limited to analyse the environmental impacts of uncertainties and off-design functioning rather than the failures. The analysis, based on the contributions of the literature over more than 20 years, was carried out manually and allowed to identify and classify the application fields, the types of identifiable failures and the approaches used for their determination, for the analysis of their risk of occurrence and for their eco-assessment. The different classifications have also been intersected with each other and all the proposed approaches have been discussed in detail, highlighting the advantages and disadvantages in relation to eco-assessment. From the study emerged a growing and heterogeneous interest on the subject by the scientific community, and a certain independence of the analysed methods with respect to traditional approaches of both failure risk analysis and eco-assessment. Great attention of the methods about product functioning has been highlighted, in addition to the use of tests, simulations, FMEA (failure mode and effect analysis)-based approaches and knowledge databases to determine the failures, while statistical methods are preferred to support risks analysis and LCA (life cycle assessment) for environmental impact calculation. If, in the coming years, this argument also spreads in industry, the results provided by this review could be exploited as a first framework for practitioners.

Graphical abstract
Spaces of positive intermediate curvature metrics
Authors: Frenck Georg , Kordaß Jan-Bernhard
Published: June 2021

In this paper we study spaces of Riemannian metrics with lower bounds on intermediate curvatures. We show that the spaces of metrics of positive p-curvature and k-positive Ricci curvature on a given high-dimensional $$\mathrm {Spin}$$
Spin
-manifold have many non-trivial homotopy groups provided that the manifold admits such a metric.
Qualitative Comparative Analysis and robust sufficiency
Authors: Baumgartner Michael
Published: June 2021

Some methodologists take the search target of Qualitative Comparative Analysis (QCA) to be causal INUS-conditions, others contend that QCA should instead be used to search for some form of sufficiency that is more substantive than mere Boolean sufficiency. While the notion of an INUS-condition has a long and uncontroversial definitional history, Adrian Dusa, in a recent paper, is the first to explicitly define a notion of substantive sufficiency, which he labels robust sufficiency. Dusa’s definition, however, is vacuous in real-life research contexts. As an alternative, the first part of this paper non-vacuously defines robust sufficiency and supplies a corresponding notion of minimality, which—I argue—captures Dusa’s conceptual intentions. In the second part, I then report and discuss the results of a series of simulation experiments benchmarking the performance of the different QCA solution types in recovering robust sufficiency and minimality.
Evaluation of the productivity of hospital-based researchers: comparative study between the h-index and the h(fa)-index
Authors: Sebo Paul , de Lucia Sylvain
Published: June 2021

The h-index is often used to evaluate researchers and to measure their respective contributions to the scientific community. However, it does not take into account the relative contribution of each author to the articles. We aimed to assess the added value of the h(fa)-index, an index introducing a weighting factor for the first author. This cross-sectional study was conducted in March 2020 in Switzerland. We selected all hospital-based senior physicians practicing internal medicine or family medicine in the six university hospitals. Using Web of Science, we retrieved the h-index and computed the h(fa)-index of all physicians with a non-zero h-index. We used Spearman coefficients to examine the correlation between the two indices and Cohen’s kappa to determine the inter-rater agreement. 244 physicians were included in the study (men: 63%). They had a median h-index of 3 (IQR 11) and a median h(fa) index of 4.5 (IQR 14). The correlation between the two indices was very high (rho 0.98, p-value < 0.001). However, the inter-rater agreement was only moderate (Kappa 0.59 [95% CI 0.56–0.64]). The h(fa)-index was able to correct the categorization of the researchers in about 1/3 of the cases (agreement 63.4%). Although it is very challenging to evaluate researchers with a unique indicator, these data suggest that the h(fa)-index could be a better evaluation tool of researchers’ productivity.
Routine screening for pulmonary embolism in COVID-19 patients at the emergency department: impact of D-dimer testing followed by CTPA
Authors: Korevaar Daniël A. , Aydemir Ilayda , Minnema Maartje W. , Azijli Kaoutar , Beenen Ludo F. , Heijmans Jarom , van Es Nick , al Masoudi Mohanad , Meijboom Lilian J. , Middeldorp Saskia , Nanayakkara Prabath W. , Meijer Rick I. , Bonta Peter I. , van Es Josien
Published: June 2021

COVID-19 patients have increased risk of pulmonary embolism (PE), but symptoms of both conditions overlap. Because screening algorithms for PE in COVID-19 patients are currently lacking, PE might be underdiagnosed. We evaluated a screening algorithm in which all patients presenting to the ED with suspected or confirmed COVID-19 routinely undergo D-dimer testing, followed by CT pulmonary angiography (CTPA) if D-dimer is ≥ 1.00 mg/L. Consecutive adult patients presenting to the ED of two university hospitals in Amsterdam, The Netherlands, between 01-10-2020 and 31-12-2020, who had a final diagnosis of COVID-19, were retrospectively included. D-dimer and CTPA results were obtained. Of 541 patients with a final diagnosis of COVID-19 presenting to the ED, 25 (4.6%) were excluded because D-dimer was missing, and 71 (13.1%) because they used anticoagulation therapy. Of 445 included patients, 185 (41.6%; 95%CI 37.0–46.3) had a D-dimer ≥ 1.00 mg/L. CTPA was performed in 169 of them, which showed PE in 26 (15.4%; 95%CI 10.3–21.7), resulting in an overall detection rate of 5.8% (95%CI 3.9–8.4) in the complete study group. In patients with and without PE at CTPA, median D-dimer was 9.84 (IQR 3.90–29.38) and 1.64 (IQR 1.17–3.01), respectively (p < 0.001). PE prevalence increased with increasing D-dimer, ranging from 1.2% (95%CI 0.0–6.4) if D-dimer was 1.00–1.99 mg/L, to 48.6% (95%CI 31.4–66.0) if D-dimer was ≥ 5.00 mg/L. In conclusion, by applying this screening algorithm, PE was identified in a considerable proportion of COVID-19 patients. Prospective management studies should assess if this algorithm safely rules-out PE if D-dimer is < 1.00 mg/L.
An Ode to ODA against all Odds? A Novel Game-Theoretical and Empirical Reappraisal of the Terrorism-Aid Nexus
Authors: Sadik-Zada Elkhan Richard
Published: June 2021

The present inquiry revisits the influence of the fourth religious wave of modern terrorism on the allocation of official development assistance (ODA). The theoretical framework is predicated first on comprehensive review of the pertinent literature on the nexus between political instability and foreign aid, augmented by the assessment of Central Intelligence Agency declassified documents and Congressional Service Reports. Based on the systematic review of the sources, the study puts forward a novel dynamic differential game theory model, which enables derivation of the scenarios for foreign aid allocation. The study finds that despite dominance of geopolitical and/or commercial interests in the allocation of aid, high incidence of terrorist attacks does not lead to less development aid, but rather catalyzes it. Subsequent empirical analysis of a dataset with 121 developing and transition economies spanning between 1970 and 2016 reveals that terrorism incidents, level of political rights, and the War on Terror had a statistically significant positive long-run and negative short-run effect on the level of foreign aid commitment of the Organisation for Economic Co-Operation and Development member states. The growth rate of foreign aid in the developing countries with a predominantly Muslim population has been systematically 0.1 to 0.85 percent greater than in non-Muslim countries. Subsequent assessment of the security bias in the allocation of aid indicates that re-securitization of aid since 1998 has led to weak diversion of aid commitment from areas with fewer terrorism incidents to jurisdictions with a greater frequency of terrorist attacks.
Decision support framework for the regional facility location and development planning problem
Authors: Kik David , Wichmann Matthias Gerhard , Spengler Thomas Stefan
Published: June 2021

Location choice is a crucial planning task with major influence on a company’s future orientation and competitiveness. It is quite complex, since multiple location factors are usually of decision-relevance, incomparable, and sometimes conflictual. Further, ongoing urbanization is associated with locational dynamics posing major challenges for the regional location management of companies and municipalities. For example, respecting urban space as location factor, a scarcity growing over time leads to different assessment and requirements on a company’s behalf. For both companies and municipalities, there is a need for location development which implies an active change of location factor characteristics. Accordingly, considering locational dynamics is vital, as they may be decisive in the location decision-making. Although certain dynamics are considered within conventional Facility Location Problem (FLP) approaches, a systematic consideration of active location development is missing so far. Consequently, they may propagate long-term unfavorable location decisions, as major potentials associated with company-driven and municipal development measures are neglected. Therefore, this paper introduces a comprehensive decision support framework for the Regional Facility Location and Development planning Problem (RFLDP). It provides an operationalization of development measures, and thus anticipates dynamic adaptations to the environment. An established multi-criteria approach is extended to this new application. A complementary guideline ensures its meaningful applicability by practitioners. Based on a real-life case study, the decision support framework’s strength for practical application is demonstrated. Here, major advantages over conventional FLP approaches are highlighted. It is shown that the proposed methodology results in alternative location decisions which are structurally superior.
On the Cooling Rate-Microstructure Relationship in Molten Metal Gas Atomization
Authors: Gianoglio Dario , Ciftci Nevaf , Armstrong Sarah , Uhlenwinkel Volker , Battezzati Livio
Published: June 2021

Gas atomization is the most used powder production technique since it provides good control on particles shape, surface oxidation and dimension. It is a rapid solidification technique involving fast cooling rates, which are strictly correlated to particle size. This relationship is typically described with a power law function that can be determined experimentally by measuring the microstructural length-scale or through the application of a heat transfer model. Both paths were exploited in the present work focusing on a gas-atomized Al-4.5Cu alloy. Atomized powders were characterized by means of X-ray diffraction, differential scanning calorimetry, light and scanning electron microscopy to investigate the relationship between cooling rate and microstructure length-scale. A recently proposed semi-empirical model was validated and discussed in terms of a physically based heat transfer approach. The change in gas-to-melt mass flow ratio (GMR) was also investigated showing that it does not affect appreciably the relationship between solidification rate and particle size, but does increase the Cu supersaturation in the powders of finer size.
Cognitive Biases in Criminal Case Evaluation: A Review of the Research
Authors: Meterko Vanessa , Cooper Glinda
Published: June 2021

Psychological heuristics are an adaptive part of human cognition, helping us operate efficiently in a world full of complex stimuli. However, these mental shortcuts also have the potential to undermine the search for truth in a criminal investigation. We reviewed 30 social science research papers on cognitive biases in criminal case evaluations (i.e., integrating and drawing conclusions based on the totality of the evidence in a criminal case), 18 of which were based on police participants or an examination of police documents. Only two of these police participant studies were done in the USA, with the remainder conducted in various European countries. The studies provide supporting evidence that lay people and law enforcement professionals alike are vulnerable to confirmation bias, and there are other environmental, individual, and case-specific factors that may exacerbate this risk. Six studies described or evaluated the efficacy of intervention strategies, with varying evidence of success. Further research, particularly in the USA, is needed to evaluate different approaches to protect criminal investigations from cognitive biases.
Chronic AdipoRon Treatment Mimics the Effects of Physical Exercise on Restoring Hippocampal Neuroplasticity in Diabetic Mice
Authors: Lee Thomas H , Ahadullah  , Christie Brian R , Lin Kangguang , Siu Parco Ming-fai , Zhang Li , Yuan Ti-fei , Komal Pragya , Xu Aimin , So Kwok-fai , Yau Suk-yu
Published: June 2021

Administration of exercise mimetic drugs could be a novel therapeutic approach to combat comorbid neurodegeneration and metabolic syndromes. Adiponectin is an adipocyte-secreted hormone. In addition to its antidiabetic effect, adiponectin mediates the antidepressant effect of physical exercise associated with adult hippocampal neurogenesis. The antidiabetic effect of the adiponectin receptor agonist AdipoRon has been demonstrated, but its potential pro-cognitive and neurotrophic effects in the hippocampus under diabetic condition are still unclear. This study reported that chronic AdipoRon treatment for 2 weeks improved hippocampal-dependent spatial recognition memory in streptozotocin-induced diabetic mice. Besides, AdipoRon treatment increased progenitor cell proliferation and neuronal differentiation in the hippocampal dentate gyrus (DG) of diabetic mice. Furthermore, AdipoRon treatment significantly increased dendritic complexity, spine density, and N-methyl-D-aspartate receptor-dependent long-term potentiation (LTP) in the dentate region, and increased BDNF levels in the DG of diabetic mice. AdipoRon treatment activated AMPK/PGC-1α signalling in the DG, whereas increases in cell proliferation and LTP were not observed when PGC-1α signalling was pharmacologically inhibited. In sum, chronic AdipoRon treatment partially mimics the benefits of physical exercise for learning and memory and hippocampal neuroplasticity in the diabetic brain. The results suggested that AdipoRon could be a potential physical exercise mimetic to improve hippocampal plasticity and hence rescue learning and memory impairment typically associated with diabetes.
Analysis of groundwater table variability and trend using ordinary kriging: the case study of Sylhet, Bangladesh
Authors: Hasan Khairul , Paul Sondipon , Chy Tareq Jamal , Antipova Anzhelika
Published: June 2021

Many developing countries experience widespread groundwater declination. Sustainable management actions include generation of an accurate groundwater distribution based on an extensive groundwater monitoring network which is often cost prohibiting in the context of a developing country such as Bangladesh. Further, such knowledge is lacking for the Sylhet region where groundwater was documented to be under tremendous pressure. Specifically, the gap in the current literature exists regarding groundwater trends and its areal extent for this region. This paper bridges the gap in research by focusing on trends and spatial and temporal variation of groundwater level changes for this area. This study addresses this problem by creating groundwater level predictions at the ungauged areas using geostatistical methods applied to a detailed set of data. In this study, the spatial variability of annual-average depth to the water table at 46 observation wells in the Sylhet division in Bangladesh is analyzed for 2000, 2005, 2010, and 2015. The geostatistical analysis applies the ordinary kriging method with cross-validation to create the water table maps for the study area. The results indicate a substantial increase in groundwater depths during the studied period from 2000 to 2015 in some locations in the study area. Importantly, this work identifies the vulnerable zones in the area due to the groundwater lowering trend. The study adds to the groundwater management research in developing countries and focuses on the spatial and temporal groundwater variation. The findings from the modeling exercise contribute to identification of the vulnerable areas and therefore help policymakers in making informed decisions to manage groundwater resources in this sensitive region sustainably.
Temporal assessment of heavy metal concentration and surface water quality representing the public health evaluation from the Meghna River estuary, Bangladesh
Authors: Safiur Rahman M. , Shafiuddin Ahmed A. S. , Rahman Md. Moshiur , Omar Faruque Babu S. M. , Sultana Sharmin , Sarker Shafiqul Islam , Awual Rabiul , Rahman Mohammad Majibur , Rahman Mostafizur
Published: June 2021

The Meghna River, the largest and the widest river in Bangladesh, is important for navigation, irrigation, fish spawning and shelter, industrial usages, and drinking water sources for millions of people living in nearby areas. The present study illustrated the seasonal variation of some physicochemical parameters and the four heavy metals (Cr, As, Cd, and Pb) distribution in the surface water of Meghna River estuary. It also evaluated the human health risk for adult and children due to directly contact with the surface water through ingestion and dermal pathways. The ranges of metal concentration in the study area were found in the descending order as: Cr (0.036–0.054; mean 0.045 ± 0.005) > As (0.012–0.036; mean 0.024 ± 0.007) > Cd (0.009–0.050; mean 0.018 ± 0.012) > Pb (0.007–0.014; mean 0.009 ± 0.007). In most cases, the concentrations of As, Cr, Pb, and Cd surpassed the guideline limits of human consumption. However, the one-way ANOVA study revealed that the average concentrations of the selected metals in the ten sampling sites were not significantly different at a 95% confidence level. Therefore, it is assumed that the metal contamination in the study area might have been caused due to the anthropogenic sources along with the natural phenomenon. The distribution of the metal contents and the physicochemical parameters in the surface water greatly were significantly different concerning both winter and summer seasons at a 95% confidence level. The evaluated hazard quotient (HQ) and the hazard index (HI) for the investigated metal compounds were in the acceptable limit (< 1). In addition, the attribution of metal contents did not overweigh the carcinogenic risk (CR) range (10–6 to 10–4), and the adults are more susceptible than the children. Although the risk is within the acceptable level, but adequate monitoring aspects should be implemented to control surface water pollution especially for the metal discharge to the river estuary.
How formal institutional antecedents affect Tunisian venture creation decision scripts
Authors: Haj brahim Abdallah , Morched Salim , Boujelbene Younes
Published: June 2021

The aim of this paper is to reveal the impact of three Tunisian formal institutional systems on their venture creation decision through the study of entrepreneurial scripts of Tunisians nascent entrepreneur post-revolution phase. The method adopted in this study is the cognitive map. This research enriches entrepreneurial process literature by examining a finer-grained linkage between the degree of the development of Tunisian formal institutional systems and the level of expertise in the decision stage as an early process of venture creation. To do this, the cognitive approach is adopted by using the structural analysis method as a tool for structuring ideas and collective reflections. In the field of entrepreneurship, the mentioned approach has been the subject of few empirical studies. This leads to a better understanding of individual’s cognitive universe (actors, coaches, managers, entrepreneurs, etc.). It is important in the context of this study to identify and analyze the influence of formal institutional antecedents on the cognition of Tunisian nascent entrepreneurs and consequently on their decision. Experiments done on 120 born entrepreneurs incubating in the nurseries allowed to present, in the form of a collective map, the formal institutional antecedents that seem to affect their decisions to become entrepreneurs through their NVCD scripts.
Meta-study on the relationship between profitability and liquidity of enterprises in macroeconomic and institutional environment
Authors: Jaworski Jacek , Czerwonka Leszek
Published: June 2021

The main aim of the paper is to determine the relationship between profitability and financial liquidity of a company using meta-analysis. This method is based on a synthesis of many previous studies with the application of econometric tools. The results of the study show that, taking into account 16 economies, it is not possible to identify a common effect describing the relationship between the profitability of enterprises and their financial liquidity measured by the current liquidity ratio. The results of individual empirical studies that underlie the meta-analysis are diverse. This means that there are moderators of the strength and direction of this dependence associated with macroeconomic and institutional conditions. We attempted to separate them by means of meta-regression. This method involves the use of a regression model, where data are derived from both meta-analysis and external sources. We diagnosed two statistically significant moderators of the strength and direction of the relationship between profitability and liquidity. These are two factors: (i) private sector crediting and (ii) capital market development. Our paper contributes to the development of the existing knowledge by summarizing and binding previous individual empirical studies on the relationship between profitability and liquidity of enterprises and identifying factors affecting this relationship. This knowledge can assist financial managers in making more efficient decisions related to liquidity and working capital management.
Stochastic orderings of multivariate elliptical distributions
Authors: Yin Chuancun
Published: June 2021

For two n-dimensional elliptical random vectors X and Y, we establish an identity for $\mathbb{E}[f({\bf Y})]- \mathbb{E}[f({\bf X})]$, where $f\,{:}\, \mathbb{R}^n \rightarrow \mathbb{R}$ satisfies some regularity conditions. Using this identity we provide a unified method to derive sufficient and necessary conditions for classifying multivariate elliptical random vectors according to several main integral stochastic orders. As a consequence we obtain new inequalities by applying the method to multivariate elliptical distributions. The results generalize the corresponding ones for multivariate normal random vectors in the literature.
CAN MACHINE LEARNING CATCH THE COVID-19 RECESSION?
Authors: Goulet Coulombe Philippe , Marcellino Massimiliano , Stevanović Dalibor
Published: June 2021

Based on evidence gathered from a newly built large macroeconomic dataset (MD) for the UK, labelled UK-MD and comparable to similar datasets for the United States and Canada, it seems the most promising avenue for forecasting during the pandemic is to allow for general forms of nonlinearity by using machine learning (ML) methods. But not all nonlinear ML methods are alike. For instance, some do not allow to extrapolate (like regular trees and forests) and some do (when complemented with linear dynamic components). This and other crucial aspects of ML-based forecasting in unprecedented times are studied in an extensive pseudo-out-of-sample exercise.
Water cycle algorithm: an approach for improvement of navigational strategy of multiple humanoid robots
Authors: Muni Manoj Kumar , Kumar Saroj , Parhi Dayal R. , Pandey Krishna Kant
Published: June 2021

This paper presents an efficient water cycle algorithm based on the processes of water cycle with movement of streams and rivers in to the sea. This optimization algorithm is applied to obtain the optimal feasible path with minimum travel duration during motion planning of both single and multiple humanoid robots in both static and dynamic cluttered environments. This technique discards the rainfall process considering falling water droplets forming streams during raining and the process of flowing. The flowing process searches the solution space and finds the more accurate solution and represents the local search. Motion planning of humanoids is carried out in V-REP software. The performance of proposed algorithm is tested in experimental scenario under laboratory conditions and shows the developed algorithm performs well in terms of obtaining optimal path length and minimum time span of travel. Here, navigational analysis has been performed on both single as well as multiple humanoid robots. Statistical analysis of results obtained from both simulation and experimental environments is carried out for both single and multiple humanoids, along with the comparison with another existing optimization technique that indicate the strength and effectiveness of the proposed water cycle algorithm.
Black Holes in the Universe
Authors: Novikov I.D.
Published: June 2021

Some 30 years ago very few scientists thought that black holes may really exist. Attention focussed on the black hole hypothesis after neutron stars had been discovered. It was rather surprising that astrophysicists immediately ‘welcomed’ black holes. They found their place not only in the remnants of supernova explosions but also in the nuclei of galaxies and quasars.
Automated Search for LSB Galaxies in the Nearby Universe
Authors: Morshidi Z. , Davies J.I. , Smith R.M.
Published: June 2021

We have carried out a large area survey for nearby LSB galaxies to try and answer the following questions:

1.

How are LSB galaxies distributed relative to the normal HSB galaxies? Do they have the same clustering properties suggesting that they trace the same mass distribution?

2.

What are the implications of the clustering properties on galaxy formation scenarios?

3.

Can they account for faint blue galaxies at higher redshifts?

4.

Is there any difference between the field and cluster LSB galaxies?

2. The Survey

We have devised an automated technique to pick out local LSB galaxies using 65 UKSTU photographic plates corresponding to 2187 sq.°. We have imposed stringent selection criteria in order to minimise the background contamination. Our galaxies have μ0 ≥ 22.5 B mag arcsec-2 α ≥ 3.0 arcseconds and BT ≤ 20.0. Our survey areas are confined to the Fornax Cluster, the NGC1400, Sculptor and Dorado Groups and the fields between them. The survey, which was carried out in three stages over a period of 2 years, has produced detections of 2435 LSB galaxies (32 galaxies per field). We have estimated the background contamination in three ways: first, by a limited redshift sample, secondly, by Ferguson’s (1989) classification on the Fornax plate and finally, by a numerical simulation of background galaxies. The first method produced an estimate of 14 galaxies per field, while the second and the third methods produced the same estimate of 19 galaxies.
HI Distribution in Extreme Dwarf Irregulars and Dwarf Spheroidals
Authors: Carignan Claude
Published: June 2021

Recent studies (Puche & Westpfahl 1994, Young & Lo 1996) have shown that the distribution of HI in some extreme low luminosity dwarf irregular galaxies (e.g. M81dwA, Holmberg I, Leo A) tends to have a ring-like (or shell-like) distribution which suggests that a single burst of star formation could expell most of the remaining ISM (or at least a large fraction of it) from the system. In view of this, Puche & Westpfahl (1994) suggested that in dwarf spheroidal galaxies, the HI should be found at large radii since no young stellar population is observed in most of them.
Star Formation Activity in High MH/LB Galaxies
Authors: Van Zee L.
Published: June 2021

The results of an investigation of the evolutionary status of fifteen gas-rich, low surface brightness dwarf galaxies (LSBDGs) are presented. LSBDGs are defined by unusually high values of MH/LB and the presence of extended HI envelopes. At both the present epoch and the past, the star formation process appears to be inefficient: the LSBDGs are underluminous for their HI mass and very little active star formation is currently observed. Analysis of global optical colors and elemental enrichments indicate that these objects are not “young” systems; rather, star formation has been occurring for several Gyr. One clue to the star formation history of these objects is that the global gas density is significantly lower than the Toomre instability criterion throughout the gas disk. Local peaks in the HI surface density, however, approach the instability criterion and are correlated with sites of active star formation. Thus, while star formation appears to be inhibited globally, the local gas distribution plays a crucial role in regulating the star formation activity in these low mass galaxies.
Dwarf Elliptical Galaxies in the M81 Group: The Structure and Stellar Populations of BK5N and F8D1
Authors: Armandroff Taft E. , Caldwell Nelson , Da Costa G.S. , Seitzer Patrick
Published: June 2021

The M81 group is one of the nearest groups of galaxies, but its properties are quite different from those of the Local Group. It has therefore provided a different environment for the evolution of its member galaxies. We have carried out a CCD survey of the M81 group to search for analogs to Local Group dwarf elliptical (dE) galaxies. All the M81 dwarfs previously identified in photographic surveys were recovered and we also discovered several new systems whose surface brightnesses fall within the range found for Local Group dE’s.

We have obtained HST WFPC2 images through the F555W and F814W filters of two M81 group dE’s: BK5N and a new system, designated F8D1. The resulting color-magnitude diagrams show the upper two magnitudes of the red giant branch. The I magnitudes of the red giant branch tip in both galaxies yield distances that are consistent with membership in the M81 group. Surface brightness and total magnitude measurements indicate that BK5N and F8D1 have similar central surface brightness (24.5 and 25.4 mag arcsec-2 in V, respectively), but F8D1 is larger length scale results in it being 3 magnitudes more luminous than BK5N. BK5N lies on the relation between central surface brightness and absolute magnitude defined by Local Group dwarf ellipticals, but F8D1 does not. F8D1 is more luminous for its central surface brightness than the relation predicts, similar to the large low surface brightness dwarf galaxies found in, for example, Virgo. The mean color of the giant branch is used to establish the mean abundance of each galaxy. F8D1, the more luminous galaxy, is significantly more metal rich ([Fe/H] ≈ -1.0) than BK5N ([Fe/H] ≈ -1.7). Both BK5N and F8D1 lie on the relation between absolute magnitude and metal abundance defined by Local Group dwarf ellipticals. However, as regards the relation between central surface brightness and metal abundance, BK5N again follows the Local Group dwarfs, while F8D1 deviates significantly from this relation. This suggests that the total amount of luminous matter is more fundamental in controlling metal enrichment than the surface density of luminous matter. We have also used the color width of the giant branch compared with the photometric errors to establish abundance ranges in both galaxies, the sizes of which are comparable to those in Local Group dE’s.
New Light on the Origin of Nebular He II Emission in Young Starbursts
Authors: Schaerer Daniel
Published: June 2021

In the Local Group few Hɪɪ regions exhibit nebular Heɪɪ λ4686 emission, indicative of unusually high excitation. Approximately eight such nebulae are known, all located in low metallicity environments (IC 1613, SMC, LMC) except the Galactic ring nebula G2.4+1.4 (Esteban et al. 1992). The best studied case is the nebula S 3 surrounding the WO3 star DR 1 (Garnett et al. 1991, Kingsburgh &: Barlow 1995). Except for two cases (N 44C, N159 F; Stasińska et al. 1986, Pakull & Angebault 1986) the nebulae are asociated with early WN (cf. Niemela et al. 1991) and WO stars.

So far approximately 50 to 60 extragalactic Hɪɪ regions showing nebular Heɪɪ λ4686 are known (Campbell et al. 1986, Izotov et al. 1994, 1997a). Most of them are found in H II galaxies, BCDs and related objects from low metallicity samples used for determinations of the primordial helium abundance. The most prominent case is the low metallicity (Z) record holder I Zw 18. He II emission is typically on the order of 1-5 % of Hβ.

Different ionization mechanisms (photoionization by hot stars, shock excitation, photoionization by X-rays) have been put forward to explain the required hard spectrum (Garnett et al. 1991).

The first quantitative approach to address this problem are the evolutionary synthesis models of Schaerer (1996) and Schaerer & Vacca (1997), which include well tested evolutionary tracks and recent spherically expanding non-LTE atmosphere models appropriate for WR and O stars.
Overview, Formulation and Current Situation for Precession-Nutation
Authors: Capitaine N.
Published: June 2021

This paper describes the conventional models for precession and nutation, the current procedure for taking them into account in the reduction of highly accurate observations, the recent IAU recommendations on this topic, as well as the current situation for theory and observations. This emphasizes the imperfections in the conventional models and in the current procedure which are not in consistency either with the adoption of the new International Conventional Celestial Reference System (ICRS) or with the high accuracy and resolution of the current observations of Earth rotation. This addresses the question of the adoption of a new formulation and of an improved model combining precession and nutation of the equator with respect to the ICRS as well as the adoption of a revised definition of the Celestial Ephemeris Pole.
Sofa: Standards of Fundamental Astronomy: Progress and Plans
Authors: Wallace P.T.
Published: June 2021

At its 1994 General Assembly, the International Astronomical Union resolved to introduce new arrangements to establish and maintain an accessible and authoritative set of constants, algorithms and procedures that implement standard models used in fundamental astronomy. The initiative was the responsibility of the Working Group on Astronomical Standards (WGAS), part of Division 1 of the IAU, and the set of procedures and constants was named SOFA, for “Standards Of Fundamental Astronomy”. The background to the IAU Resolution is given by Fukushima (1995) and Wallace (1996).
Interactions between Planets and Small Bodies: Introduction
Authors: Marov M. , Rickman H.
Published: June 2021

The exploration of our Solar System is rapidly growing in importance as a scientific discipline. During the last decades, great progress has been achieved as the result of space missions to planets and small bodies and improved remote-sensing methods, as well as due to refined techniques of laboratory measurements and a rapid progress in theoretical studies, involving the development of various astrophysical and geophysical evolutionary models, based in particular on the approach of comparative planetology. In the crossroads of astronomy and geophysics, recent years have seen a growing understanding of the importance of impact phenomena throughout the history of the Solar System and, therefore, the necessity to get more insight into the problem of interactions of planets and small bodies. This importance is clearly manifested by the observed cratering records of planetary surfaces and such dramatic events as the explosions of the comet P/Shoemaker-Levy 9 fragments in Jupiter’s atmosphere in 1994, that of the Tunguska object over Siberia in 1908, and the Chicxulub event dating back to the end of the Cretaceous.
Tidal Splitting of Comets in Earth’s Vicinity
Authors: Rickman H. , Greenberg J.M.
Published: June 2021

We present a study of the influence of tidal splitting In order to clarify the role of comets as Earth impactors and bringers of organics to the young planet. Based on low values for the density and material strength, as indicated by Comet Shoemaker-Levy 9, we have modeled the evolution of a comet in an orbit leading to Earth impact. We find that cometary nuclei impacting the Earth with radii ≥ 0.1 - 0.3 km will split just before doing so. Nuclei of several km radius will split when passing within a distance ≤, 5 - 8 Earth radii. Cometary nuclei with radii ≥ 1km stand a much larger chance of being tidally split than of hitting the Earth. Consequently, streams of fragments and debris form in Earth-crossing orbits more often than large nuclei cause impacts. The mass distribution of impacting material is shifted toward sub-km objects, whereby the survivability of organics may be significantly increased. If the cometary impactors move in orbits where ≥ 5 passages within Earth’s Roche zone are expected, we estimate that most of the material reaching Earth’s surface will appear in the form of split fragments.