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Book ; Conference proceedings: Umbruch in der Landwirtschaft - Chance für die Kulturlandschaft?

Konrad, Christian

[eine Dokumentaton eines Symposiums des Distelvereins, Verein zur Förderung des Lebensraumes östliches Weinviertel/Marchfeld, vom 30. November 1988 im Raiffeisenhaus Wien]

(Club Niederösterreich ; 1989,2)

1989

Author's details	Christian Konrad
Series title	Club Niederösterreich ; 1989,2
Collection
Keywords	Österreich ; Landwirtschaft ; Naturschutz
Subject	Agrarwirtschaft ; Agrarsektor ; Landwirtschaftlicher Sektor
Size	114 S. : Ill.
Publishing place	Wien
Publishing country	Austria
Document type	Book ; Conference proceedings
HBZ-ID	HT003643151
Database	Catalogue ZB MED Nutrition, Environment, Agriculture

In stock of ZB MED Bonn / Germany

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908/543	order for loan	Geschlossenes Magazin (U2)

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Book ; Online: Graph Reconstruction via MIS Queries

Konrad, Christian / O'Sullivan, Conor / Traistaru, Victor

2024

Abstract: We consider the Graph Reconstruction problem given only query access to the input graph via a Maximal Independent Set oracle. In this setting, in each round, the player submits a query consisting of a subset of vertices to the oracle, and the oracle ... ...

Abstract	We consider the Graph Reconstruction problem given only query access to the input graph via a Maximal Independent Set oracle. In this setting, in each round, the player submits a query consisting of a subset of vertices to the oracle, and the oracle returns any maximal independent set in the subgraph induced by the queried vertices. The goal for the player is to learn all the edges of the input graph. In this paper, we give tight (up to a logarithmic factor) upper and lower bounds for this problem: 1. We give a randomized query algorithm that uses $O(\Delta^2 \log n)$ non-adaptive queries and succeeds with high probability to reconstruct an $n$-vertex graph with maximum degree $\Delta$. Using the probabilistic method, we also show that a non-adaptive deterministic algorithm that executes $O(\Delta^3 \log n)$ queries exists. 2. We give two lower bounds that apply to arbitrary adaptive randomized algorithms that succeed with probability greater than $\frac{1}{2}$. We show that, for such algorithms, $\Omega(\Delta^2)$ rounds are necessary in graphs of maximum degree $\Delta$, and that $\Omega(\log n)$ rounds are necessary even when the input graph is an $n$-vertex cycle.
Keywords	Computer Science - Data Structures and Algorithms
Subject code	511 ; 005
Publishing date	2024-01-11
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Lebe Balance im Betrieb

Konrad, Christian

(In: Sauerland, Martin; Braun, Ottmar L.; Raab, Gerhard (Ed.), Gesundheit, Freiheit und Ausgewogenheit. Trends in der Personal- und Organisationsentwicklung (S. 9-18). Hamburg: Windmühle Verlag (Serie: Arbeitshefte Führungspsychologie, Band 80))

2017

Abstract: Vorgestellt wird das betriebliche Präventionsprogramm "Lebe Balance im Betrieb", das im Institut für Wissenschaftliche Psychologische Prävention Freiburg (IWPP) für die AOK Baden-Württemberg entwickelt wurde. Ziel des Programms ist die Prävention von ... ...

Title translation	Live balance at worksite
Series title	In: Sauerland, Martin; Braun, Ottmar L.; Raab, Gerhard (Ed.), Gesundheit, Freiheit und Ausgewogenheit. Trends in der Personal- und Organisationsentwicklung (S. 9-18). Hamburg: Windmühle Verlag (Serie: Arbeitshefte Führungspsychologie, Band 80)
Abstract	Vorgestellt wird das betriebliche Präventionsprogramm "Lebe Balance im Betrieb", das im Institut für Wissenschaftliche Psychologische Prävention Freiburg (IWPP) für die AOK Baden-Württemberg entwickelt wurde. Ziel des Programms ist die Prävention von arbeitsbedingten psychischen Störungen und Erkrankungen in Betrieben. "Lebe Balance im Betrieb" basiert auf den Erkenntnissen der Resilienzforschung und setzt diese in Form eines erfahrungsbasierten Kurssystems um. "Lebe Balance im Betrieb" ist eine Erweiterung des Präventionsprogramms "Lebe Balance", das seit 2013 von der AOK Baden-Württemberg flächendeckend für die Allgemeinbevölkerung angeboten und vom Zentralinstitut für Seelische Gesundheit Mannheim der Universität Heidelberg wissenschaftlich evaluiert wird. Zunächst wird der wissenschaftliche Hintergrund des Programms erläutert (Anstieg stressbedingter psychischer Erkrankungen; Resilienz- und Risikoprofile). Zentrales Ziel ist die Verbesserung der Flexibilität in der Anpassung an moderne Arbeitsstrukturen durch die Stärkung allgemeiner personaler Schutzfaktoren unter Berücksichtigung des individuellen Risikoprofils. Das Programm setzt sich aus folgenden Modulen zusammen: (1) Achtsam dem Leben und sich selbst begegnen. (2) Der wohlwollende innere Coach. (3) Werte bewusst machen. (4) Soziale Netze und wertschätzende Kommunikation. (5) Veränderungen wagen und Probleme lösen. (6) Balance am Arbeitsplatz.
Keywords	Achtsamkeit ; Beruflicher Stress ; Gesundheit am Arbeitsplatz ; Mental Disorders ; Mindfulness ; Occupational Health ; Occupational Stress ; Preventive Mental Health Services ; Protective Factors ; Protektive Faktoren ; Präventive psychosoziale Dienste ; Psychische Störungen ; Resilience (Psychological) ; Resilienz ; Risikofaktoren ; Risk Factors ; Social Networks ; Soziale Netzwerke
Language	German
Document type	Article
Database	PSYNDEX

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Book ; Online: On Two-Pass Streaming Algorithms for Maximum Bipartite Matching

Konrad, Christian / Naidu, Kheeran K.

2021

Abstract: We study two-pass streaming algorithms for Maximum Bipartite Matching (MBM). All known two-pass streaming algorithms for MBM operate in a similar fashion: They compute a maximal matching in the first pass and find 3-augmenting paths in the second in ... ...

Abstract	We study two-pass streaming algorithms for Maximum Bipartite Matching (MBM). All known two-pass streaming algorithms for MBM operate in a similar fashion: They compute a maximal matching in the first pass and find 3-augmenting paths in the second in order to augment the matching found in the first pass. Our aim is to explore the limitations of this approach and to determine whether current techniques can be used to further improve the state-of-the-art algorithms. We give the following results: We show that every two-pass streaming algorithm that solely computes a maximal matching in the first pass and outputs a $(2/3+\epsilon)$-approximation requires $n^{1+\Omega(\frac{1}{\log \log n})}$ space, for every $\epsilon > 0$, where $n$ is the number of vertices of the input graph. This result is obtained by extending the Ruzsa-Szemer\'{e}di graph construction of [GKK, SODA'12] so as to ensure that the resulting graph has a close to perfect matching, the key property needed in our construction. This result may be of independent interest. Furthermore, we combine the two main techniques, i.e., subsampling followed by the Greedy matching algorithm [Konrad, MFCS'18] which gives a $2-\sqrt{2} \approx 0.5857$-approximation, and the computation of \emph{degree-bounded semi-matchings} [EHM, ICDMW'16][KT, APPROX'17] which gives a $\frac{1}{2} + \frac{1}{12} \approx 0.5833$-approximation, and obtain a meta-algorithm that yields Konrad's and Esfandiari et al.'s algorithms as special cases. This unifies two strands of research. By optimizing parameters, we discover that Konrad's algorithm is optimal for the implied class of algorithms and, perhaps surprisingly, that there is a second optimal algorithm. We show that the analysis of our meta-algorithm is best possible. Our results imply that further improvements, if possible, require new techniques.
Keywords	Computer Science - Data Structures and Algorithms ; F.2.2 ; G.2.2
Subject code	005
Publishing date	2021-07-16
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: The diagnostic and prognostic value of IgG and IgA anti-citrullinated protein antibodies in patients with early rheumatoid arthritis.

Sieghart, Daniela / Konrad, Christian / Swiniarski, Sascha / Haslacher, Helmuth / Aletaha, Daniel / Steiner, Günter

Frontiers in immunology

2023 Volume 13, Page(s) 1096866

Abstract: Objectives: Anti-citrullinated peptide antibodies (ACPA) are specific markers for rheumatoid arthritis (RA) and typically measured by assays employing a cyclic citrullinated peptide (CCP) as antigen. This study was aimed at investigating the diagnostic ... ...

Abstract	Objectives: Anti-citrullinated peptide antibodies (ACPA) are specific markers for rheumatoid arthritis (RA) and typically measured by assays employing a cyclic citrullinated peptide (CCP) as antigen. This study was aimed at investigating the diagnostic performance of anti-CCP2 and anti-CCP3 IgG and IgA assays in patients with early RA with a particular focus on the potential prognostic value of IgA ACPA. Methods: The anti-CCP3.1 assay (Inova Diagnostics) measuring IgG and IgA antibodies simultaneously was compared to anti-CCP2 IgG and IgA assays (Thermo Fisher Scientific) employing sera of 184 early RA patients, 360 disease controls and 98 healthy subjects. Results: Anti-CCP2 IgG and IgA assays showed high specificity versus disease controls (98.9%; 99.4%). Sensitivity was 52.2% (IgG) and 28.8% (IgA), resulting in positive likelihood ratios (LR+) of 47.5 (IgG) and 48.0 (IgA). The anti-CCP3.1 assay proved slightly more sensitive than the anti-CCP2 IgG assay (56%) but specificity was markedly lower (90.8% versus disease controls). However, when using a threefold higher cut-off specificity of the anti-CCP3.1 assay increased (97.5%) while sensitivity (52.7%) became comparable to the anti-CCP2 IgG assay resulting in a LR+ of 21.5. Anti-CCP2 IgA antibodies did not increase the diagnostic sensitivity of ACPA testing, but IgA positive patients showed diminished responses to treatment with anti-TNF biologicals compared to patients who had only IgG antibodies. Conclusion: Specificity of ACPA assays should be adjusted to reduce the risk of misclassification and a false positive diagnosis. Determination of ACPA IgA might provide important prognostic information concerning therapeutic responses.
MeSH term(s)	Humans ; Anti-Citrullinated Protein Antibodies ; Prognosis ; Tumor Necrosis Factor Inhibitors ; Sensitivity and Specificity ; Arthritis, Rheumatoid/diagnosis ; Arthritis, Rheumatoid/drug therapy ; Immunoglobulin G ; Immunoglobulin A
Chemical Substances	Anti-Citrullinated Protein Antibodies ; Tumor Necrosis Factor Inhibitors ; Immunoglobulin G ; Immunoglobulin A
Language	English
Publishing date	2023-01-05
Publishing country	Switzerland
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2606827-8
ISSN	1664-3224 ; 1664-3224
ISSN (online)	1664-3224
ISSN	1664-3224
DOI	10.3389/fimmu.2022.1096866
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Book ; Online: $\mathcal{O}(\log\log{n})$ Passes is Optimal for Semi-Streaming Maximal Independent Set

Assadi, Sepehr / Konrad, Christian / Naidu, Kheeran K. / Sundaresan, Janani

2023

Abstract: In the semi-streaming model for processing massive graphs, an algorithm makes multiple passes over the edges of a given $n$-vertex graph and is tasked with computing the solution to a problem using $O(n \cdot \text{polylog}(n))$ space. Semi-streaming ... ...

Abstract	In the semi-streaming model for processing massive graphs, an algorithm makes multiple passes over the edges of a given $n$-vertex graph and is tasked with computing the solution to a problem using $O(n \cdot \text{polylog}(n))$ space. Semi-streaming algorithms for Maximal Independent Set (MIS) that run in $O(\log\log{n})$ passes have been known for almost a decade, however, the best lower bounds can only rule out single-pass algorithms. We close this large gap by proving that the current algorithms are optimal: Any semi-streaming algorithm for finding an MIS with constant probability of success requires $\Omega(\log\log{n})$ passes. This settles the complexity of this fundamental problem in the semi-streaming model, and constitutes one of the first optimal multi-pass lower bounds in this model. We establish our result by proving an optimal round vs communication tradeoff for the (multi-party) communication complexity of MIS. The key ingredient of this result is a new technique, called hierarchical embedding, for performing round elimination: we show how to pack many but small hard $(r-1)$-round instances of the problem into a single $r$-round instance, in a way that enforces any $r$-round protocol to effectively solve all these $(r-1)$-round instances also. These embeddings are obtained via a novel application of results from extremal graph theory -- in particular dense graphs with many disjoint unique shortest paths -- together with a newly designed graph product, and are analyzed via information-theoretic tools such as direct-sum and message compression arguments. Comment: 60 pages, 14 figures
Keywords	Computer Science - Data Structures and Algorithms ; Computer Science - Computational Complexity ; Computer Science - Distributed ; Parallel ; and Cluster Computing
Subject code	005
Publishing date	2023-12-20
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Constructing Large Matchings via Query Access to a Maximal Matching Oracle

Khalil, Lidiya Khalidah binti / Konrad, Christian

2020

Abstract: Multi-pass streaming algorithm for Maximum Matching have been studied since more than 15 years and various algorithmic results are known today, including $2$-pass streaming algorithms that break the $1/2$-approximation barrier, and $(1-\epsilon)$- ... ...

Abstract	Multi-pass streaming algorithm for Maximum Matching have been studied since more than 15 years and various algorithmic results are known today, including $2$-pass streaming algorithms that break the $1/2$-approximation barrier, and $(1-\epsilon)$-approximation streaming algorithms that run in $O(\text{poly} \frac{1}{\epsilon})$ passes in bipartite graphs and in $O( (\frac{1}{\epsilon})^{\frac{1}{\epsilon}})$ or $O(\text{poly} (\frac{1}{\epsilon}) \cdot \log n)$ passes in general graphs, where $n$ is the number of vertices of the input graph. However, proving impossibility results for such algorithms has so far been elusive, and, for example, even the existence of $2$-pass small space streaming algorithms with approximation factor $0.999$ has not yet been ruled out. The key building block of all multi-pass streaming algorithms for Maximum Matching is the Greedy matching algorithm. Our aim is to understand the limitations of this approach: How many passes are required if the algorithm solely relies on the invocation of the Greedy algorithm? In this paper, we initiate the study of lower bounds for restricted families of multi-pass streaming algorithms for Maximum Matching. We focus on the simple yet powerful class of algorithms that in each pass run Greedy on a vertex-induced subgraph of the input graph. In bipartite graphs, we show that $3$ passes are necessary and sufficient to improve on the trivial approximation factor of $1/2$: We give a lower bound of $0.6$ on the approximation ratio of such algorithms, which is optimal. We further show that $\Omega( \frac{1}{\epsilon})$ passes are required for computing a $(1-\epsilon)$-approximation, even in bipartite graphs. Last, the considered class of algorithms is not well-suited to general graphs: We show that $\Omega(n)$ passes are required in order to improve on the trivial approximation factor of $1/2$. Comment: To appear at FSTTCS 2020, fixed some typos
Keywords	Computer Science - Data Structures and Algorithms
Subject code	005
Publishing date	2020-09-28
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Improved Weighted Matching in the Sliding Window Model

Alexandru, Cezar-Mihail / Dvořák, Pavel / Konrad, Christian / Naidu, Kheeran K.

2022

Abstract: We consider the Maximum-weight Matching (MWM) problem in the streaming sliding window model of computation. In this model, the input consists of a sequence of weighted edges on a given vertex set $V$ of size $n$. The objective is to maintain an ... ...

Abstract	We consider the Maximum-weight Matching (MWM) problem in the streaming sliding window model of computation. In this model, the input consists of a sequence of weighted edges on a given vertex set $V$ of size $n$. The objective is to maintain an approximation of a maximum-weight matching in the graph spanned by the $L$ most recent edges, for some integer $L$, using as little space as possible. Prior to our work, the state-of-the-art results were a $(3.5+\varepsilon)$-approximation algorithm for MWM by Biabani et al. [ISAAC'21] and a $(3+\varepsilon)$-approximation for (unweighted) Maximum Matching (MM) by Crouch et al. [ESA'13]. Both algorithms use space $\tilde{O}(n)$. We give the following results: 1. We give a $(2+\varepsilon)$-approximation algorithm for MWM with space $\tilde{O}(\sqrt{nL})$. Under the reasonable assumption that the graphs spanned by the edges in each sliding window are simple, our algorithm uses space $\tilde{O}(n \sqrt{n})$. 2. In the $\tilde{O}(n)$ space regime, we give a $(3+\varepsilon)$-approximation algorithm for MWM, thereby closing the gap between the best-known approximation ratio for MWM and MM. Similar to Biabani et al.'s MWM algorithm, both our algorithms execute multiple instances of the $(2+\varepsilon)$-approximation $\tilde{O}(n)$-space streaming algorithm for MWM by Paz and Schwartzman [SODA'17] on different portions of the stream. Our improvements are obtained by selecting these substreams differently. Furthermore, our $(2+\varepsilon)$-approximation algorithm runs the Paz-Schwartzman algorithm in reverse direction over some parts of the stream, and in forward direction over other parts, which allows for an improved approximation guarantee at the cost of increased space requirements.
Keywords	Computer Science - Data Structures and Algorithms
Subject code	005
Publishing date	2022-04-10
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Robust Lower Bounds for Graph Problems in the Blackboard Model of Communication

Konrad, Christian / Robinson, Peter / Zamaraev, Viktor

2021

Abstract: We give lower bounds on the communication complexity of graph problems in the multi-party blackboard model. In this model, the edges of an $n$-vertex input graph are partitioned among $k$ parties, who communicate solely by writing messages on a shared ... ...

Abstract	We give lower bounds on the communication complexity of graph problems in the multi-party blackboard model. In this model, the edges of an $n$-vertex input graph are partitioned among $k$ parties, who communicate solely by writing messages on a shared blackboard that is visible to every party. We show that any non-trivial graph problem on $n$-vertex graphs has blackboard communication complexity $\Omega(n)$ bits, even if the edges of the input graph are randomly assigned to the $k$ parties. We say that a graph problem is non-trivial if the output cannot be computed in a model where every party holds at most one edge and no communication is allowed. Our lower bound thus holds for essentially all key graph problems relevant to distributed computing, including Maximal Independent Set (MIS), Maximal Matching, ($\Delta+1$)-coloring, and Dominating Set. In many cases, e.g., MIS, Maximal Matching, and $(\Delta+1)$-coloring, our lower bounds are optimal, up to poly-logarithmic factors.
Keywords	Computer Science - Data Structures and Algorithms ; Computer Science - Distributed ; Parallel ; and Cluster Computing
Publishing date	2021-03-11
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online ; Thesis: Molecular analysis of insulin signaling mechanisms in Echinococcus multilocularis and their role in the host parasite interaction in the alveolar echinococcosis

Konrad, Christian

2007

Author's details	vorgelegt von: Christian Konrad
Language	English
Size	Online-Ressource
Document type	Book ; Online ; Thesis
Thesis / German Habilitation thesis	Univ., Diss--Würzburg, 2007
Database	Former special subject collection: coastal and deep sea fishing

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