542 research outputs found

    Resource Allocation for Outdoor-to-Indoor Multicarrier Transmission with Shared UE-side Distributed Antenna Systems

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    In this paper, we study the resource allocation algorithm design for downlink multicarrier transmission with a shared user equipment (UE)-side distributed antenna system (SUDAS) which utilizes both licensed and unlicensed frequency bands for improving the system throughput. The joint UE selection and transceiver processing matrix design is formulated as a non-convex optimization problem for the maximization of the end-to-end system throughput (bits/s). In order to obtain a tractable resource allocation algorithm, we first show that the optimal transmitter precoding and receiver post-processing matrices jointly diagonalize the end-to-end communication channel. Subsequently, the optimization problem is converted to a scalar optimization problem for multiple parallel channels, which is solved by using an asymptotically optimal iterative algorithm. Simulation results illustrate that the proposed resource allocation algorithm for the SUDAS achieves an excellent system performance and provides a spatial multiplexing gain for single-antenna UEs.Comment: accepted for publication at the IEEE Vehicular Technology Conference (VTC) Spring, Glasgow, Scotland, UK, May 201

    Topic Embeddings – A New Approach to Classify Very Short Documents Based on Predefined Topics

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    Traditional unsupervised topic modeling approaches like Latent Dirichlet Allocation (LDA) lack the ability to classify documents into a predefined set of topics. On the other hand, supervised methods require significant amounts of labeled data to perform well on such tasks. We develop a new unsupervised method based on word embeddings to classify documents into predefined topics. We evaluate the predictive performance of this novel approach and compare it to seeded LDA. We use a real-world dataset from online advertising, which is comprised of markedly short documents. Our results indicate the two methods may complement one another well, leading to remarkable sensitivity and precision scores of ensemble learners trained thereupon

    Postpartum Blood Loss in Women Treated for Intrahepatic Cholestasis of Pregnancy

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    OBJECTIVE To evaluate postpartum blood loss in women with treated intrahepatic cholestasis of pregnancy. METHODS In a retrospective case-control study, 15,083 deliveries including 348 women with intrahepatic cholestasis of pregnancy (2.3%) were analyzed from 2004 to 2014. To adjust for differences in baseline characteristics, a propensity analysis was performed and women in the control group were matched to the women in the intrahepatic cholestasis of pregnancy group in a 5:1 ratio. Blood loss was analyzed by estimated blood loss and Δ hemoglobin (Hb, difference between prepartum and postpartum Hb). A subgroup analysis regarding severity of intrahepatic cholestasis of pregnancy based on maximum bile acid level (mild [less than 40 micromoles/L], moderate [40-99 micromoles/L], and severe intrahepatic cholestasis of pregnancy [100 micromoles/L or greater]) was performed. Differences in estimated blood loss, ΔHb, and meconium staining between subgroups were analyzed. A Spearman rank correlation was performed to evaluate the association of bile acid levels and blood loss within subgroups. RESULTS Estimated blood loss (median 400 [300-600] mL compared with 400 [300-600] mL, P=.22), ΔHb (14.0 [5.0-22.0] compared with 12.0 [4.0-21.0] g/L, P=.09), meconium staining (14.5% compared with 11.4%, P=.12), and number of stillbirths after 26 weeks of gestation (0.6% compared with 1.8%, P=.10) were not significantly different in the study compared with the control group. In moderate and severe intrahepatic cholestasis of pregnancy, meconium staining was observed significantly more often compared with that in a control group (23.0% and 32.3% compared with 11.4%, P<.01). There was no correlation between estimated blood loss or ΔHb and severity of intrahepatic cholestasis of pregnancy. CONCLUSIONS In our cohort of women with intrahepatic cholestasis of pregnancy who are treated with ursodeoxycholic acid and have planned delivery (induction of labor or planned cesarean delivery) at 38 weeks of gestation, no differences in postpartum blood loss were seen

    HemoCue®, an Accurate Bedside Method of Hemoglobin Measurement?

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    Objective. Evaluate the accuracy of this bedside method to determinehemoglobin (Hb) concentration in general surgery over a wide range of Hbvalues and to determine potential sources of error. Methods. Accuracy of Hbmeasurement using HemoCue® (AB Leo Diagnostics, Helsinborg, Sweden) wasassessed in 140 surgical blood samples using 7 HemoCue® devices incomparison with a CO-Oximeter (IL 482, Instrumentation Laboratory,Lexington, MA). To analyze potential sources of error, packed red cells andfresh frozen plasma were reconstituted to randomized Hb levels of 2-18g/dL. Results. In the surgical blood samples, the Hb concentrationdetermined by the CO-Oximeter (HbCOOX) ranged from 5.1 to 16.7 g/dL and theHb concentration measured by HemoCue® (HbHC) from 4.7 to 16.0 g/dL. Bias(HbCOOX - HbHC) between HbCOOX and HbHC was 0.6 ± 0.6 g/dL(mean ± SD) or 5.4 ± 5.0% (p < 0.001). Also in thereconstituted blood, the bias between HbCOOX and HbHC was significant (0.2± 0.3 g/dL or 2.1 ± 3.2%; p < 0.001). Themicrocuvette explained 68% of the variability between HbCOOX andHbHC. HemoCue® thus underestimates the Hb concentration by2-5% and exhibits a 8-10 times higher variability withonly 86.4% of HbHC being within ± 10% of HbCOOX.Conclusion. Although the mean bias between HbCOOX and HbHC was relativelylow, Hb measurement by HemoCue® exhibited a significant variability.Loading multiple microcuvettes and averaging the results may increase theaccuracy of Hb measurement by HemoCue

    DISKNET – A Platform for the Systematic Accumulation of Knowledge in IS Research

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    The accumulation of knowledge is key for any discipline, IS being no exception. With the number of publications, theoretical constructs, and empirical findings growing, surging demand for structuring and meta-analysis is foreseeable. We introduce DISKNET, an online platform that enables the extraction, exploration, and aggregation of construct’s definitions, semantic relations, and analytical relations. While these aspects exhibit a rather standardized structure in theory, their practical documentation is non-uniform, highly dispersed, and tricky to seize technically. This has impeded the efficiency and effectiveness of review and meta-analytical processes, and resulted in a fragmented theoretical superstructure. We suggest that tool support for systematic knowledge accumulation is a central step to counteract these issues and to build to a consistent body of knowledge within the IS discipline. The current prototype of DISKNET draws on a large sample of SEM-based studies to demonstrate relevant design principles for a platform for systematic accumulation of knowledge

    Inklusionsunternehmen: Zukunftsprozesse erfolgreich gestalten - Analyse, Bedarfe, Förderempfehlungen: Eine Projektstudie

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    Vor dem Hintergrund digitaler und ökologischer Transformationsprozesse sowie der Globalisierung und des demografischen Wandels war es Ziel der von Juni bis September 2021 durchgeführten Projektstudie, die kurz- und mittelfristigen Herausforderungen zu beschreiben, vor denen Inklusions- und Zuverdienstbetriebe stehen, entsprechende Bedarfe zu identifizieren und daraus resultierende Förderempfehlungen zu formulieren. Insbesondere sollte überprüft werden, ob und in welcher Weise Inklusions- und Zuverdienstbetriebe, vor dem Hintergrund des inklusiven Auftrages, bei der Bewältigung der Strukturveränderungen mit Förderungen unterstützt werden könnten. Es wird belegt, dass Inklusions- und Zuverdienstbetriebe aufgrund ihrer erforderlichen Markt- und Wettbewerbsfähigkeit bei der gleichzeitigen Ausübung des sozialpolitischen Auftrages zur Inklusion in einem außergewöhnlichen Spannungsfeld stehen. Das führt dazu, dass sie mehr noch als andere kleine und mittlere Unternehmen von den Auswirkungen der Marktveränderung betroffen sind, weil es für sie schwieriger ist flexibel darauf zu reagieren. Gleichzeitig sind öffentliche Wirtschafts- oder Strukturförderungsprogramme für einen Großteil der gemeinnützigen, sozialen Unternehmen nicht zugänglich. Dies betrifft auch einige Hilfen während der Corona-Pandemie. Die vielfach bei Inklusions- und Zuverdienstbetrieben vorherrschende Rechtsform „gemeinnützig“ versperrt den Zugang zu bereitgestellten Wirtschaftshilfen, zum Beispiel im Bereich Digitalisierung. Die Studie "Inklusionsunternehmen - Zukunftsprozesse erfolgreich gestalten", arbeitet die aktuellen Herausforderungen und vielfältigen strukturellen Anpassungsbedarfe heraus, denen sich Inklusionsfirmen stellen müssen, wenn sie als Akteure des allgemeinen Arbeitsmarktes konkurrenzfähig bleiben wollen. Daraus abgeleitet gibt der Bericht konkrete Empfehlungen, wie öffentliche und private Förderer die annähernd 1.000 Inklusionsbetriebe Deutschlands bei der Strukturanpassung unterstützen können

    Flow evaluation software for four-dimensional flow MRI: a reliability and validation study

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    PURPOSE Four-dimensional time-resolved phase-contrast cardiovascular magnetic resonance imaging (4D flow MRI) enables blood flow quantification in multiple vessels, which is crucial for patients with congenital heart disease (CHD). We investigated net flow volumes in the ascending aorta and pulmonary arteries by four different postprocessing software packages for 4D flow MRI in comparison with 2D cine phase-contrast measurements (2D PC). MATERIAL AND METHODS 4D flow and 2D PC datasets of 47 patients with biventricular CHD (median age 16, range 0.6-52 years) were acquired at 1.5 T. Net flow volumes in the ascending aorta, the main, right, and left pulmonary arteries were measured using four different postprocessing software applications and compared to offset-corrected 2D PC data. Reliability of 4D flow postprocessing software was assessed by Bland-Altman analysis and intraclass correlation coefficient (ICC). Linear regression of internal flow controls was calculated. Interobserver reproducibility was evaluated in 25 patients. RESULTS Correlation and agreement of flow volumes were very good for all software compared to 2D PC (ICC ≥ 0.94; bias ≤ 5%). Internal controls were excellent for 2D PC (r ≥ 0.95, p < 0.001) and 4D flow (r ≥ 0.94, p < 0.001) without significant difference of correlation coefficients between methods. Interobserver reliability was good for all vendors (ICC ≥ 0.94, agreement bias < 8%). CONCLUSION Haemodynamic information from 4D flow in the large thoracic arteries assessed by four commercially available postprocessing applications matches routinely performed 2D PC values. Therefore, we consider 4D flow MRI-derived data ready for clinical use in patients with CHD

    Genetic association of objective sleep phenotypes with a functional polymorphism in the neuropeptide S receptor gene

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    Background: The neuropeptide S receptor (NPSR1) and its ligand neuropeptide S (NPS) have received increased attention in the last few years, as both establish a previously unknown system of neuromodulation. Animal research studies have suggested that NPS may be involved in arousal/wakefulness and may also have a crucial role in sleep regulation. The single nucleotide polymorphism (SNP) rs324981 in NPSR1 has begun to shed light on a function of the NPS-system in human sleep regulation. Due to an amino acid exchange, the T-allele leads to an increased sensitivity of the NPSR1. In the only genomewide association study to date on circadian sleep parameters in humans, an association was found between rs324981 and regular bedtime. However, the sleep parameters in this study were only measured by self-rating. Therefore, our study aimed to replicate these findings using an objective measure of sleep. Methods: The study included n = 393 white subjects (62–79 years) who participated in an actigraphic assessment for determining sleep duration, rest duration, sleep onset, rest onset and sleep onset latency. Genotyping of the SNP rs324981 was performed using the TaqMan OpenArray System. Results: The genotype at rs324981 was not significantly associated with rest onset (bedtime) or sleep onset (p = .146 and p = .199, respectively). However, the SNP showed a significant effect on sleep- and rest duration (p = .007 and p = .003, respectively). Subjects that were homozygous for the minor T-allele had a significantly decreased sleep- and rest duration compared to A-allele carriers. Conclusion: The results of this study indicate that the sleep pattern in humans is influenced by the NPS-system. However, the previously reported association between bedtime and rs324981 could not be confirmed. The current finding of decreased sleep duration in T/T allele carriers is in accordance with studies in rodents reporting similar results after NPS application.:Background; Methods; Results; Conclusion

    Quantitative evaluation of aortic valve regurgitation in 4D flow cardiac magnetic resonance: at which level should we measure?

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    PURPOSE To find the best level to measure aortic flow for quantification of aortic regurgitation (AR) in 4D flow CMR. METHODS In 27 congenital heart disease patients with AR (67% male, 31 ± 16 years) two blinded observers measured antegrade, retrograde, net aortic flow volumes and regurgitant fractions at 6 levels in 4D flow: (1) below the aortic valve (AV), (2) at the AV, (3) at the aortic sinus, (4) at the sinotubular junction, (5) at the level of the pulmonary arteries (PA) and (6) below the brachiocephalic trunk. 2D phase contrast (2DPC) sequences were acquired at the level of PA. All patients received prior transthoracic echocardiography (TTE) with AR severity grading according to a recommended multiparametric approach. RESULTS After assigning 2DPC measurements into AR grading, agreement between TTE AR grading and 2DPC was good (κ = 0.88). In 4D flow, antegrade flow was similar between the six levels (p = 0.87). Net flow was higher at level 1-2 than at levels 3-6 (p < 0.05). Retrograde flow and regurgitant fraction at level 1-2 were lower compared to levels 3-6 (p < 0.05). Reproducibility (inter-reader agreement: ICC 0.993, 95% CI 0.986-0.99; intra-reader agreement: ICC 0.982, 95%CI 0.943-0.994) as well as measurement agreement between 4D flow and 2DPC (ICC 0.994; 95%CI 0.989 - 0.998) was best at the level of PA. CONCLUSION For estimating severity of AR in 4D flow, best reproducibility along with best agreement with 2DPC measurements can be expected at the level of PA. Measurements at AV or below AV might underestimate AR

    Signal Thresholding Segmentation of Ventricular Volumes in Young Patients with Various Diseases—Can We Trust the Numbers?

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    In many cardiac diseases, right and left ventricular volumes in systole and diastole are diagnostically and prognostically relevant. Measurements are made by segmentation of the myocardial borders on cardiac magnetic resonance (CMR) images. Automatic detection of myocardial contours is possible by signal thresholding techniques, but must be validated before use in clinical settings. Biventricular volumes were measured in end-diastole (EDVi) and in end-systole (ESVi) both manually and with the MassK application, with signal thresholds at 30%, 50%, and 70%. Stroke volumes (SV) and cardiac indices (CI) were calculated from volumetric measurements and from flow measured in the ascending aorta and the main pulmonary artery, and both methods were compared. Reproducibility of volumetric measurements was tested in 20 patients. Measurements were acquired in 94 patients aged 15 ± 9 years referred for various conditions. EDVi and ESVi of both ventricles were largest with manual segmentation and inversely proportional to the MassK threshold. Manual and k30 SV and CI corresponded best to flow measurements. Interobserver variability was low for all volumes manually and with MassK. In conclusion, manual and 30% threshold-based biventricular volume segmentation agree best with two-dimensional, phantom-corrected phase contrast flow measurements in a young cardiac referral population and are well reproducible
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