404 research outputs found

    Flight Gate Assignment with a Quantum Annealer

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    Optimal flight gate assignment is a highly relevant optimization problem from airport management. Among others, an important goal is the minimization of the total transit time of the passengers. The corresponding objective function is quadratic in the binary decision variables encoding the flight-to-gate assignment. Hence, it is a quadratic assignment problem being hard to solve in general. In this work we investigate the solvability of this problem with a D-Wave quantum annealer. These machines are optimizers for quadratic unconstrained optimization problems (QUBO). Therefore the flight gate assignment problem seems to be well suited for these machines. We use real world data from a mid-sized German airport as well as simulation based data to extract typical instances small enough to be amenable to the D-Wave machine. In order to mitigate precision problems, we employ bin packing on the passenger numbers to reduce the precision requirements of the extracted instances. We find that, for the instances we investigated, the bin packing has little effect on the solution quality. Hence, we were able to solve small problem instances extracted from real data with the D-Wave 2000Q quantum annealer.Comment: Updated figure

    Lingulodinium machaerophorum expansion over the last centuries in the Caspian Sea reflects global warming

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    This article is made available through the Brunel Open Access Publishing Fund. Copyright @ Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License.We analysed dinoflagellate cyst assemblages in four short sediment cores, two of them dated by radionuclides, taken in the south basin of the Caspian Sea. The interpretation of the four sequences is supported by a collection of 27 lagoonal or marine surface sediment samples. A sharp increase in the biomass of the dinocyst occurs after 1967, especially owing to Lingulodinium machaerophorum. Considering nine other cores covering parts or the whole of Holocene, this species started to develop in the Caspian Sea only during the last three millennia. By analysing instrumental data and collating existing reconstructions of sea level changes over the last few millennia, we show that the main forcing of the increase of L. machaerophorum percentages and of the recent dinocyst abundance is global climate change, especially sea surface temperature increase. Sea level fluctuations likely have a minor impact. We argue that the Caspian Sea has entered the Anthropocene

    Trends of research productivity across author gender and research fields: A multidisciplinary and multi-country observational study

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    Bibliographic properties of more than 75 million scholarly articles, are examined and trends in overall research productivity are analysed as a function of research field (over the period of 1970-2020) and author gender (over the period of 2006-2020). Potential disruptive effects of the Covid-19 pandemic are also investigated. Over the last decade (2010-2020), the annual number of publications have invariably increased every year with the largest relative increase in a single year happening in 2019 (more than 6% relative growth). But this momentum was interrupted in 2020. Trends show that Environmental Sciences and Engineering Environmental have been the fastest growing research fields. The disruption in patterns of scholarly publication due to the Covid-19 pandemic was unevenly distributed across fields, with Computer Science, Engineering and Social Science enduring the most notable declines. The overall trends of male and female productivity indicate that, in terms of absolute number of publications, the gender gap does not seem to be closing in any country. The trends in absolute gap between male and female authors is either parallel (e.g., Canada, Australia, England, USA) or widening (e.g., majority of countries, particularly Middle Eastern countries). In terms of the ratio of female to male productivity, however, the gap is narrowing almost invariably, though at markedly different rates across countries. While some countries are nearing a ratio of .7 and are well on track for a 0.9 female to male productivity ratio, our estimates show that certain countries (particularly across the Middle East) will not reach such targets within the next 100 years. Without interventional policies, a significant gap will continue to exist in such countries. The decrease or increase in research productivity during the first year of the pandemic, in contrast to trends established before 2020, was generally parallel for male and female authors. There has been no substantial gender difference in the disruption due to the pandemic. However, opposite trends were found in a few cases. It was observed that, in some countries (e.g., The Netherlands, The United States and Germany), male productivity has been more negatively affected by the pandemic. Overall, female research productivity seems to have been more resilient to the disruptive effect of Covid-19 pandemic, although the momentum of female researchers has been negatively affected in a comparable manner to that of males

    Forced vibration analysis of laminated composite plates under the action of a moving vehicle

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    This paper provides a finite element analysis of laminated composite plates under the action of a moving vehicle. The vehicle is modeled as a rigid body with four suspension systems, each consisting of a springdashpot. Overall, the vehicle possesses three degrees of freedom: vertical, rolling, and pitching motions. The equations of motion of the plate are deduced based on first-order shear deformation theory. Using the EulerLagrange equations, the system of coupled equations of motion is extracted and solved by using the Newmark time discretization scheme. The algorithm is validated through the comparison of both the free and forced vibration results provided by the present model and exact or numerical results reported in the literature. The effects are investigated of several system parameters on the dynamic response

    Effect of alveolar ridge preservation with PDFDBA on orthodontic tooth movement rate, formation of gingival invagination and root resorption: A randomized, controlled pilot study

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    Tooth extraction results in resorptive remodeling of the alveolar bone, but alveolar ridge preservation procedure maintains the original shape of the extraction socket. This may be beneficial for space closure by orthodontic tooth movement (OTM). In the current pilot study for randomized controlled clinical trial the effect of alveolar ridge preservation with partial demineralized freezedried bone allograft (PDFDBA) on OTM rate, formation of gingival invagination and root resorption was evaluated. Both mandibular first premolars of 6 patients were extracted due to orthodontic treatment. In a split-mouth study design, alveolar ridge preservation was performed on one side, while the other side served as a control and the extraction socket healed naturally. After 6 weeks of healing period, the canines were moved to the extraction site to close the extraction space. Eight weeks later, the amount of OTM was measured. After space closure, the extraction sites were examined for the presence of gingival invagination. Root resorption was evaluated on digital panoramic radiographs. Photographs were taken for documentation. There was no significant difference in OTM rate between the ridge preserved areas and naturally healed sockets. Gingival invagination formed in 5 of 6 naturally healed sockets; none of the ridge preserved areas showed formation of gingival invagination. No root resorption was observed in any of the teeth adjacent to the extraction sites. Alveolar ridge preservation with PDFDBA has no effect on the rate of OTM and root resorption but prevents formation of gingival invagination during orthodontic space closure

    Effect of Attachment Behaviors Training on Maternal Competence attainment in Nulliparous Adolescent Women

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    BACKGROUND AND OBJECTIVE: Adolescent pregnancy is a public health issue that requires knowledge, motivation, and skills, and the lack of it leads to a deficiency in mother competence. The aim of this study was to determine the effect of attachment behaviors training on maternal role competence in nulliparous adolescent women. METHODS: This clinical trial study, was conducted on 73 nulliparous Adolescent women at 28-32 gestational age attending the Educational centers dependent on Iran University of Medical Sciences. They were randomly divided into intervention and control groups. Three sessions of group training were held for mothers of interventional groups regarding Fetal Attachment Behaviors (Including counting the movements of the fetus and registration it, imagining the appearance of the fetus, talking with the fetus, and etc.). The control group received usual care. The Parenting Sense of Competence Scale questionnaire (score range: 17-102) was completed and assessed before the intervention and 10 days after delivery. FINDINGS: There was no statistically significant difference between the groups before the intervention in terms of the total score of Parenting Sense of Competence. 10 days after delivery, the mean score of maternal competence was 60.86 ±9.75 and 44.44±12.99 which was significantly higher compared to the control group (p<0.001). CONCLUSION: The results of this study showed that attachment behaviors training is effective in obtaining the competence of adolescent mothers

    MR defecography: A diagnostic test for the evaluation of pelvic floor motion in patients with dyssynergic defecation after biofeedback therapy

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    Background: Dyssynergic defecation is a major cause of chronic functional constipation as a common digestive complaint. We clinically evaluated the effects of biofeedback therapy on the pelvic floor motion indices through magnetic resonance (MR) defecography, quality of life and depression in patients with dyssynergic defecation. Methods: In this clinical trial study, among patients referring to the Colorectal Clinic of Hazrat Rasoul Hospital, 22 subjects were randomly assigned into two equal groups (n= 11) to receive either standard only or biofeedback and standard therapy. Dynamic changes of the pelvic floor were measured by MR defecography. During the simulated defecation, two MR defecography dynamic indices including abnormal anorectal angle change and perineal descent were measured before and after treatment. The effects of biofeedback therapy on patients' symptoms, quality of life and severity of depression were assessed and compared with the standard therapy. Statistical analysis was carried out using independent t-test and Mann-Whitney test. Results: Paradox index (p< 0.001), perineal descent index (p< 0.001), depression (p< 0.1), physical function (p< 0.001), vitality (p< 0.001) and role emotion (p< 0.001) significantly improved in the biofeedback therapy group in contrast to the standard therapy SDT group. Conclusion: Biofeedback therapy appears to be effective in improving symptoms of functional constipation and dysfunction of pelvic floor motion as well as patient's quality of life and depression state. MR defecography is able to show the changes in dynamic indices of the pelvic floor through biofeedback therapy

    Brane-f(R)f(R) gravity and dark matter

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    The collision-free Boltzmann equation is used in the context of brane-f(R)f(R) gravity to derive the virial theorem. It is shown that the virial mass is proportional to certain geometrical terms appearing in the Einstein field equations and contributes to gravitational energy and that such a geometric mass can be attributed to the virial mass discrepancy in a cluster of galaxies. In addition, the galaxy rotation curves are studied by utilizing the concept of conformal symmetry and notion of conformal Killing symmetry. The field equations may then be obtained in an exact parametric form in terms of the parameter representing the conformal factor. This provides the possibility of studying the behavior of the angular velocity of a test particle moving in a stable circular orbit. The tangential velocity can be derived as a function of the conformal factor and integration constants, resulting in a constant value at large radial distances. Relevant phenomenon such as the deflection of light passing through a region where the rotation curves are flat and the radar echo delay are also studied.Comment: 12 pages, 2 figures, to appear in PR

    Slow recognition of seminal papers and fast growth of author connectivity in economics

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    A bird’s-eye view of the economics literature and its temporal evolution during the last three decades is provided by analysing titles, abstracts, keywords, reference lists and author affiliations of nearly 204,000 economics papers. Major divisions of the literature are objectively identified through exploring patterns of term co-mention in their titles and abstracts. Temporal research trends are also quantified, and influential references are determined through patterns of co-citation of references in the reference lists of these papers. Analyses show that the literature of economics tends to lag in the adoption of emerging research and is reliant on a traditional knowledge base. Of more than 1,250 references that have had a local burst of citation, the average and maximum gap between their publication year and the onset of recognition has been respectively 10 and 47 years. Influential economics papers typically have to wait for a decade before their recognition comes along, and this phenomenon has intensified over the last three decades. Another observation is the sharp rise in author connectivity and globalisation in economics research. International collaboration in the field of economics shows a distinct acceleration since 2013. If current trend continues, in few years, the number of internationally collaborated economics papers published each year will surpass that of domestically produced papers. Economists may be traditionalists, in that, they are hesitant in giving recognition to new research or creating new research trends, but they cannot be considered insular, as they have become notably well-connected and collaborative
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