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  1. Article ; Online: Distributed Quantization for Partially Cooperating Sensors Using the Information Bottleneck Method

    Steffen Steiner / Abdulrahman Dayo Aminu / Volker Kuehn

    Entropy, Vol 24, Iss 438, p

    2022  Volume 438

    Abstract: This paper addresses the optimization of distributed compression in a sensor network with partial cooperation among sensors. The widely known Chief Executive Officer (CEO) problem, where each sensor has to compress its measurements locally in order to ... ...

    Abstract This paper addresses the optimization of distributed compression in a sensor network with partial cooperation among sensors. The widely known Chief Executive Officer (CEO) problem, where each sensor has to compress its measurements locally in order to forward them over capacity limited links to a common receiver is extended by allowing sensors to mutually communicate. This extension comes along with modified statistical dependencies among involved random variables compared to the original CEO problem, such that well-known outer and inner bounds do not hold anymore. Three different inter-sensor communication protocols are investigated. The successive broadcast approach allows each sensor to exploit instantaneous side-information of all previously transmitting sensors. As this leads to dimensionality problems for larger networks, a sequential point-to-point communication scheme is considered forwarding instantaneous side-information to only one successor. Thirdly, a two-phase transmission protocol separates the information exchange between sensors and the communication with the common receiver. Inspired by algorithmic solutions for the original CEO problem, the sensors are optimized in a greedy manner. It turns out that partial communication among sensors improves the performance significantly. In particular, the two-phase transmission can reach the performance of a fully cooperative CEO scenario, where each sensor has access to all measurements and the knowledge about all channel conditions. Moreover, exchanging instantaneous side-information increases the robustness against bad Wyner–Ziv coding strategies, which can lead to significant performance losses in the original CEO problem.
    Keywords distributed compression ; chief executive officer problem ; cooperating sensors ; distributed source coding ; information bottleneck ; Science ; Q ; Astrophysics ; QB460-466 ; Physics ; QC1-999
    Subject code 003
    Language English
    Publishing date 2022-03-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Correlation of Pulse Wave Transit Time with Pulmonary Artery Pressure in a Porcine Model of Pulmonary Hypertension

    Fabian Mueller-Graf / Jonas Merz / Tim Bandorf / Chiara Felicitas Albus / Maike Henkel / Lisa Krukewitt / Volker Kühn / Susanne Reuter / Brigitte Vollmar / Sven Pulletz / Stephan H. Böhm / Daniel A. Reuter / Amelie Zitzmann

    Biomedicines, Vol 9, Iss 1212, p

    2021  Volume 1212

    Abstract: For the non-invasive assessment of pulmonary artery pressure (PAP), surrogates like pulse wave transit time (PWTT) have been proposed. The aim of this study was to invasively validate for which kind of PAP (systolic, mean, or diastolic) PWTT is the best ... ...

    Abstract For the non-invasive assessment of pulmonary artery pressure (PAP), surrogates like pulse wave transit time (PWTT) have been proposed. The aim of this study was to invasively validate for which kind of PAP (systolic, mean, or diastolic) PWTT is the best surrogate parameter. To assess both PWTT and PAP in six healthy pigs, two pulmonary artery Mikro-Tip™ catheters were inserted into the pulmonary vasculature at a fixed distance: one in the pulmonary artery trunk, and a second one in a distal segment of the pulmonary artery. PAP was raised using the thromboxane A2 analogue U46619 (TXA) and by hypoxic vasoconstriction. There was a negative linear correlation between PWTT and systolic PAP ( r = 0.742), mean PAP ( r = 0.712) and diastolic PAP ( r = 0.609) under TXA. During hypoxic vasoconstriction, the correlation coefficients for systolic, mean, and diastolic PAP were consistently higher than for TXA-induced pulmonary hypertension ( r = 0.809, 0.778 and 0.734, respectively). Estimation of sPAP, mPAP, and dPAP using PWTT is feasible, nevertheless slightly better correlation coefficients were detected for sPAP compared to dPAP. In this study we establish the physiological basis for future methods to obtain PAP by non-invasively measured PWTT.
    Keywords pulmonary artery pressure (PAP) ; pulmonary hypertension (PH) ; pulse wave transit time (PWTT) ; pulse arrival time (PAT) ; pulse wave velocity (PWV) ; Biology (General) ; QH301-705.5
    Subject code 530
    Language English
    Publishing date 2021-09-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article: Environmental risk assessment of antibiotics including synergistic and antagonistic combination effects

    Marx, Conrad / Viktoria Mühlbauer / Peter Krebs / Volker Kuehn

    Science of the total environment. 2015 Aug. 15, v. 524-525

    2015  

    Abstract: The interaction-based hazard index (HIint) allows a prediction of mixture effects different from linear additivity by including information on binary mixtures between the chemicals. The aim of this study is to make a solid estimate on the possible ... ...

    Abstract The interaction-based hazard index (HIint) allows a prediction of mixture effects different from linear additivity by including information on binary mixtures between the chemicals. The aim of this study is to make a solid estimate on the possible synergistic potential of combined antibiotics and to quantify the subsequent effect for the case of the receiving river Elbe, Germany. Pieces of information on binary interactions between antibiotic groups were used from literature and from knowledge on human antibiotic combination therapy. Applying a moderate and a worst-case scenario, in terms of the interaction magnitude, resulted in 50 to 200% higher environmental risks, compared to the classical assessment approach applying simple concentration addition. A subsequent sensitivity analysis revealed that the data strength for some binary antibiotic combinations is too low to be considered for a solid estimate of synergistic effects. This led to the definition of certain preconditions in order to decide whether or not to include certain interaction information (e.g. the necessary number of interaction studies). The exclusion of information with low data strength resulted in an attenuated risk increase of 20 to 50%, based on the currently available scientific information on binary antibiotic mixtures. In order to include antibiotics with the highest share in the overall risk (macrolides, quinolones, and cephalosporins) as well as their corresponding metabolites, investigations should focus on binary interactions between them.
    Keywords cephalosporins ; environmental assessment ; humans ; macrolides ; metabolites ; prediction ; quinolones ; risk ; risk assessment ; rivers ; synergism ; therapeutics ; Germany
    Language English
    Dates of publication 2015-0815
    Size p. 269-279.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2015.04.051
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 949: Show issues Location:
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    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
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  4. Article: Representative input load of antibiotics to WWTPs: Predictive accuracy and determination of a required sampling quantity

    Marx, Conrad / Markus Ahnert / Peter Krebs / Reinhard Oertel / Sara Schubert / Viktoria Mühlbauer / Volker Kuehn

    Water research. 2015 June 01, v. 76

    2015  

    Abstract: Predicting the input loads of antibiotics to wastewater treatment plants (WWTP) using certain input data (e.g. prescriptions) is a reasonable method if no analytical data is available. Besides the spatiotemporal uncertainties of the projection itself, ... ...

    Abstract Predicting the input loads of antibiotics to wastewater treatment plants (WWTP) using certain input data (e.g. prescriptions) is a reasonable method if no analytical data is available. Besides the spatiotemporal uncertainties of the projection itself, only a few studies exist to confirm the suitability of required excretion data from literature. Prescription data with a comparatively high resolution and a sampling campaign covering 15 months were used to answer the question of applicability of the prediction approach. As a result, macrolides, sulfamethoxazole and trimethoprim were almost fully recovered close to 100% of the expected input loads. Nearly all substances of the beta-lactam family exhibit high elimination rates during the wastewater transport in the sewer system with a low recovery rate at the WWTP. The measured input loads of cefuroxime, ciprofloxacin and levofloxacin fluctuated greatly through the year which was not obvious from relatively constant prescribed amounts. The latter substances are an example that available data are not per se sufficient to monitor the actual release into the environment. Furthermore, the extensive data pool of this study was used to calculate the necessary number of samples to determine a representative annual mean load to the WWTP. For antibiotics with low seasonality and low input scattering a minimum of about 10 samples is required. In the case of antibiotics exhibiting fluctuating input loads 30 to 40 evenly distributed samples are necessary for a representative input determination. As a high level estimate, a minimum number of 20–40 samples per year is proposed to reasonably estimate a representative annual input load of antibiotics and other micropollutants.
    Keywords cefuroxime ; ciprofloxacin ; excretion ; levofloxacin ; macrolides ; pollutants ; prediction ; sulfamethoxazole ; trimethoprim ; uncertainty ; wastewater ; wastewater treatment
    Language English
    Dates of publication 2015-0601
    Size p. 19-32.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 202613-2
    ISSN 1879-2448 ; 0043-1354
    ISSN (online) 1879-2448
    ISSN 0043-1354
    DOI 10.1016/j.watres.2015.02.049
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Bonn / Germany

    Z 78/260: Show issues
    Z 3381: Show issues

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  5. Article: Mass flow of antibiotics in a wastewater treatment plant focusing on removal variations due to operational parameters

    Marx, Conrad / Norbert Günther / Sara Schubert / Reinhard Oertel / Markus Ahnert / Peter Krebs / Volker Kuehn

    Science of the total environment. 2015 Dec. 15, v. 538

    2015  

    Abstract: Wastewater treatment plants (WWTPs) are not designed to purposefully eliminate antibiotics and therefore many previous investigations have been carried out to assess their fate in biological wastewater treatment processes. In order to consolidate ... ...

    Abstract Wastewater treatment plants (WWTPs) are not designed to purposefully eliminate antibiotics and therefore many previous investigations have been carried out to assess their fate in biological wastewater treatment processes. In order to consolidate previous findings regarding influencing factors like the solid and hydraulic retention time an intensive monitoring was carried out in a municipal WWTP in Germany. Over a period of 12months daily samples were taken from the in- and effluent as well as diverse sludge streams. The 14 selected antibiotics and one metabolite cover the following classes: cephalosporins, diaminopyrimidines, fluoroquinolones, lincosamide, macrolides, penicillins, sulfonamides and tetracyclines.Out of the 15 investigated substances, the removal of only clindamycin and ciprofloxacin show significant correlations to SRT, temperature, HRT and nitrogen removal. The dependency of clindamycin's removal could be related to the significant negative removal (i.e. production) of clindamycin in the treatment process and was corrected using the human metabolite clindamycin-sulfoxide. The average elimination was adjusted from −225% to 3% which suggests that clindamycin can be considered as an inert substance during the wastewater treatment process. Based on the presented data, the mass flow analysis revealed that macrolides, clindamycin/clindamycin-sulfoxide and trimethoprim were mainly released with the effluent, while penicillins, cephalosporins as well as sulfamethoxazole were partly degraded in the studied WWTP. Furthermore, levofloxacin and ciprofloxacin are the only antibiotics under investigation with a significant mass fraction bound to primary, excess and digested sludge. Nevertheless, the sludge concentrations are highly inconsistent which leads to questionable results. It remains unclear whether the inconsistencies are due to insufficiencies in sampling and/or analytical determination or if the fluctuations can be considered reasonable for digesters. Hence, future investigations have to address antibiotic's temporal dynamics during the sludge treatment to decide whether or not the widely reported standard deviations of sludge concentrations reflect realistic fluctuations.
    Keywords cephalosporins ; ciprofloxacin ; clindamycin ; humans ; levofloxacin ; macrolides ; mass flow ; metabolites ; monitoring ; nitrogen ; penicillins ; sludge ; statistical analysis ; streams ; sulfamethoxazole ; temperature ; temporal variation ; trimethoprim ; wastewater treatment ; Germany
    Language English
    Dates of publication 2015-1215
    Size p. 779-788.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2015.08.112
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 949: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)

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