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Christoph Lange

Publications and source records attributed to Christoph Lange.

At least 37 records · Page 2Linked to original sources

Explainable AI for Bioinformatics: Methods, Tools, and Applications

Artificial intelligence (AI) systems utilizing deep neural networks (DNNs) and machine learning (ML) algorithms are widely used for solving important problems in bioinformatics, biomedical informatics, and precision medicine. However, complex DNNs or ML models, which are often perceived as opaque and black-box, can make it difficult to understand the reasoning behind their decisions. This lack of transparency can be a challenge for both end-users and decision-makers, as well as AI developers. Additionally, in sensitive areas like healthcare, explainability and accountability are not only desirable but also legally required for AI systems that can have a significant impact on human lives. Fairness is another growing concern, as algorithmic decisions should not show bias or discrimination towards certain groups or individuals based on sensitive attributes. Explainable artificial intelligence (XAI) aims to overcome the opaqueness of black-box models and provide transparency in how AI systems make decisions. Interpretable ML models can explain how they make predictions and the factors that influence their outcomes. However, most state-of-the-art interpretable ML methods are domain-agnostic and evolved from fields like computer vision, automated reasoning, or statistics, making direct application to bioinformatics problems challenging without customization and domain-specific adaptation. In this paper, we discuss the importance of explainability in the context of bioinformatics, provide an overview of model-specific and model-agnostic interpretable ML methods and tools, and outline their potential caveats and drawbacks. Besides, we discuss how to customize existing interpretable ML methods for bioinformatics problems. Nevertheless, we demonstrate how XAI methods can improve transparency through case studies in bioimaging, cancer genomics, and text mining.

q-bio.QM↗

Perspective on real-space nanophotonic field manipulation using non-perturbative light-matter coupling

The achievement of large values of the light-matter coupling in nanoengineered photonic structures can lead to multiple photonic resonances contributing to the final properties of the same hybrid polariton mode. We develop a general theory describing multi-mode light-matter coupling in systems of reduced dimensionality and we explore their novel phenomenology, validating the predictions of our theory against numerical electromagnetic simulations. On the one hand, we characterise the spectral features linked with the multi-mode nature of the polaritons. On the other hand, we show how the interference between different photonic resonances can modify the real-space shape of the electromagnetic field associated with each polariton mode. We argue that the possibility of engineering nanophotonic resonators to maximise the multi-mode mixing, and to alter the polariton modes via applied external fields, could allow for the dynamical real-space tailoring of subwavelength electromagnetic fields.

physics.optics↗

Template-Based Question Answering over Linked Geospatial Data

Large amounts of geospatial data have been made available recently on the linked open data cloud and the portals of many national cartographic agencies (e.g., OpenStreetMap data, administrative geographies of various countries, or land cover/land use data sets). These datasets use various geospatial vocabularies and can be queried using SPARQL or its OGC-standardized extension GeoSPARQL. In this paper, we go beyond these approaches to offer a question-answering engine for natural language questions on top of linked geospatial data sources. Our system has been implemented as re-usable components of the Frankenstein question answering architecture. We give a detailed description of the system's architecture, its underlying algorithms, and its evaluation using a set of 201 natural language questions. The set of questions is offered to the research community as a gold standard dataset for the comparative evaluation of future geospatial question answering engines.

cs.IR↗

OncoNetExplainer: Explainable Predictions of Cancer Types Based on Gene Expression Data

The discovery of important biomarkers is a significant step towards understanding the molecular mechanisms of carcinogenesis; enabling accurate diagnosis for, and prognosis of, a certain cancer type. Before recommending any diagnosis, genomics data such as gene expressions(GE) and clinical outcomes need to be analyzed. However, complex nature, high dimensionality, and heterogeneity in genomics data make the overall analysis challenging. Convolutional neural networks(CNN) have shown tremendous success in solving such problems. However, neural network models are perceived mostly as `black box' methods because of their not well-understood internal functioning. However, interpretability is important to provide insights on why a given cancer case has a certain type. Besides, finding the most important biomarkers can help in recommending more accurate treatments and drug repositioning. In this paper, we propose a new approach called OncoNetExplainer to make explainable predictions of cancer types based on GE data. We used genomics data about 9,074 cancer patients covering 33 different cancer types from the Pan-Cancer Atlas on which we trained CNN and VGG16 networks using guided-gradient class activation maps++(GradCAM++). Further, we generate class-specific heat maps to identify significant biomarkers and computed feature importance in terms of mean absolute impact to rank top genes across all the cancer types. Quantitative and qualitative analyses show that both models exhibit high confidence at predicting the cancer types correctly giving an average precision of 96.25%. To provide comparisons with the baselines, we identified top genes, and cancer-specific driver genes using gradient boosted trees and SHapley Additive exPlanations(SHAP). Finally, our findings were validated with the annotations provided by the TumorPortal.

q-bio.QM↗

Ultrafast two-dimensional field spectroscopy of terahertz intersubband saturable absorbers

Intersubband (ISB) transitions in semiconductor multi-quantum well (MQW) structures are promising candidates for the development of saturable absorbers at terahertz (THz) frequencies. Here, we exploit amplitude and phase-resolved two-dimensional (2D) THz spectroscopy on the sub-cycle time scale to observe directly the saturation dynamics and coherent control of ISB transitions in a metal-insulator MQW structure. Clear signatures of incoherent pump-probe and coherent four-wave mixing signals are recorded as a function of the peak electric field of the single-cycle THz pulses. All nonlinear signals reach a pronounced maximum for a THz electric field amplitude of 11 kV/cm and decrease for higher fields. We demonstrate that this behavior is a fingerprint of THz-driven carrier-wave Rabi flopping. A numerical solution of the Maxwell-Bloch equations reproduces our experimental findings quantitatively and traces the trajectory of the Bloch vector. This microscopic model allows us to design tailored MQW structures with optimized dynamical properties for saturable absorbers that could be used in future compact semiconductor-based single-cycle THz sources.

physics.optics↗

Automatically Annotating Articles Towards Opening and Reusing Transparent Peer Reviews

An increasing number of scientific publications are created in open and transparent peer review models: a submission is published first, and then reviewers are invited, or a submission is reviewed in a closed environment but then these reviews are published with the final article, or combinations of these. Reasons for open peer review include giving better credit to reviewers and enabling readers to better appraise the quality of a publication. In most cases, the full, unstructured text of an open review is published next to the full, unstructured text of the article reviewed. This approach prevents human readers from getting a quick impression of the quality of parts of an article, and it does not easily support secondary exploitation, e.g., for scientometrics on reviews. While document formats have been proposed for publishing structured articles including reviews, integrated tool support for entire open peer review workflows resulting in such documents is still scarce. We present AR-Annotator, the Automatic Article and Review Annotator which employs a semantic information model of an article and its reviews, using semantic markup and unique identifiers for all entities of interest. The fine-grained article structure is not only exposed to authors and reviewers but also preserved in the published version. We publish articles and their reviews in a Linked Data representation and thus maximize their reusability by third-party applications. We demonstrate this reusability by running quality-related queries against the structured representation of articles and their reviews.

cs.IR↗

Unveiling Scholarly Communities over Knowledge Graphs

Knowledge graphs represent the meaning of properties of real-world entities and relationships among them in a natural way. Exploiting semantics encoded in knowledge graphs enables the implementation of knowledge-driven tasks such as semantic retrieval, query processing, and question answering, as well as solutions to knowledge discovery tasks including pattern discovery and link prediction. In this paper, we tackle the problem of knowledge discovery in scholarly knowledge graphs, i.e., graphs that integrate scholarly data, and present Korona, a knowledge-driven framework able to unveil scholarly communities for the prediction of scholarly networks. Korona implements a graph partition approach and relies on semantic similarity measures to determine relatedness between scholarly entities. As a proof of concept, we built a scholarly knowledge graph with data from researchers, conferences, and papers of the Semantic Web area, and apply Korona to uncover co-authorship networks. Results observed from our empirical evaluation suggest that exploiting semantics in scholarly knowledge graphs enables the identification of previously unknown relations between researchers. By extending the ontology, these observations can be generalized to other scholarly entities, e.g., articles or institutions, for the prediction of other scholarly patterns, e.g., co-citations or academic collaboration.

cs.DL↗

Terahertz light-matter interaction beyond unity coupling strength

Achieving control over light-matter interaction in custom-tailored nanostructures is at the core of modern quantum electrodynamics [1-15]. In ultrastrongly coupled systems [5-15], excitation is repeatedly exchanged between a resonator and an electronic transition at a rate known as the vacuum Rabi frequency $Ω_R$. For $Ω_R$ approaching the resonance frequency $ω_c$, novel quantum phenomena including squeezed states [16], Dicke superradiant phase transitions [17,18], the collapse of the Purcell effect [19], and a population of the ground state with virtual photon pairs [16,20] are predicted. Yet, the experimental realization of optical systems with $Ω_R$/$ω_c$ has remained elusive. Here, we introduce a paradigm change in the design of light-matter coupling by treating the electronic and the photonic components of the system as an entity instead of optimizing them separately. Using the electronic excitation to not only boost the oscillator strength but furthermore tailor the shape of the vacuum mode, we push $Ω_R$/$ω_c$ of cyclotron resonances ultrastrongly coupled to metamaterials far beyond unity. As one prominent illustration of the unfolding possibilities, we calculate a ground state population of 0.37 virtual photons for our best structure with $Ω_R$/$ω_c$ = 1.43, and suggest a realistic experimental scenario for measuring vacuum radiation by cutting-edge terahertz quantum detection [21,22].

cond-mat.mes-hall↗

A Survey of User Expectations and Tool Limitations in Collaborative Scientific Authoring and Reviewing

Collaborative scientific authoring is increasingly being supported by software tools. Traditionally, desktop-based authoring tools had the most advanced editing features, allowed for more formatting options, and included more import/export filters. Web-based tools have excelled in their collaboration support. Recently, developers on both sides have been trying to close this gap by extending desktop-based tools to better support collaboration and by making web-based tools richer in functionality. To verify to what extent these developments actually meet the needs of researchers, we gathered precise requirements towards better tool support for scientific authoring and reviewing workflows by interviewing 213 users and studying a corpus of 27 documents. We present the design of the survey and interpret its results. The conclusion is that WYSIWYG and offline desktop authoring tools continue to be more popular among academics than text-based and online editors.

cs.DL↗

Phase-locked multi-terahertz electric fields exceeding 13 MV/cm at 190 kHz repetition rate

We demonstrate a compact source of energetic and phase-locked multi-terahertz pulses at a repetition rate of 190 kHz. Difference frequency mixing of the fundamental output of an Yb:KGW amplifier with the idler of an optical parametric amplifier in GaSe and LiGaS2 crystals yields a passively phase-locked train of waveforms tunable between 12 and 42 THz. The shortest multi-terahertz pulses contain 1.8 oscillation cycles within the intensity FWHM. Pulse energies of up to 0.16 μJ and peak electric fields of 13 MV/cm are achieved. Electro-optic sampling reveals a phase stability better than 0.1 $π$ over multiple hours combined with free CEP tunability. The scalable scheme opens the door to strong-field terahertz optics at unprecedented repetition rates.

physics.optics↗

Towards a Cloud-Based Service for Maintaining and Analyzing Data About Scientific Events

We propose the new cloud-based service OpenResearch for managing and analyzing data about scientific events such as conferences and workshops in a persistent and reliable way. This includes data about scientific articles, participants, acceptance rates, submission numbers, impact values as well as organizational details such as program committees, chairs, fees and sponsors. OpenResearch is a centralized repository for scientific events and supports researchers in collecting, organizing, sharing and disseminating information about scientific events in a structured way. An additional feature currently under development is the possibility to archive web pages along with the extracted semantic data in order to lift the burden of maintaining new and old conference web sites from public research institutions. However, the main advantage is that this cloud-based repository enables a comprehensive analysis of conference data. Based on extracted semantic data, it is possible to determine quality estimations, scientific communities, research trends as well the development of acceptance rates, fees, and number of participants in a continuous way complemented by projections into the future. Furthermore, data about research articles can be systematically explored using a content-based analysis as well as citation linkage. All data maintained in this crowd-sourcing platform is made freely available through an open SPARQL endpoint, which allows for analytical queries in a flexible and user-defined way.

cs.DL↗

The Opening Scholarly Communication in Social Sciences project OSCOSS

The OSCOSS project (Opening Scholarly Communication in Social Sciences), which will be outlined, aims at providing integrated support for all steps of the scholarly communication process. Incl. collaborative writing of a scientific paper, collecting data related to existing publications, interpreting and including data in a paper, submitting the paper for peer review, reviewing the paper, publishing an article, and, finally, facilitating its consumption by readers. The OSCOSS project will support this process considering in particular the perspective of three main actors detailed in the use case descriptions below: readers, authors and reviewers.

cs.DL↗

Decentralized creation of academic documents using a Network Attached Storage (NAS) server

Scholarly document creation continues to face various obstacles. Scholarly text production requires more complex word processors than other forms of texts because of the complex structures of citations, formulas and figures. The need for peer review, often single-blind or double-blind, creates needs for document management that other texts do not require. Additionally, the need for collaborative editing, security and strict document access rules means that many existing word processors are imperfect solutions for academics. Nevertheless, most papers continue to be written using Microsoft Word (Sadeghi et al. 2017). We here analyze some of the problems with existing academic solutions and then present an argument why we believe that running an open source academic writing solution for academic purposes, such as Fidus Writer, on a Network Attached Storage (NAS) server could be a viable alternative.

cs.DL↗

Polarized SERS of individual suspended carbon nanotubes by Pt-Re nanoantennas

We present optical nanoantennas designed for applications that require processing temperatures larger than 800°C. The antennas consist of arrays of Re/Pt bilayer strips fabricated with a lift-off-free technique on top of etched trenches. Reflectance measurements show a clear plasmonic resonance at approximately 670 nm for light polarized orthogonal to the strip axis. The functionality of the antennas is demonstrated by growing single-walled carbon nanotubes (CNTs) on top of the antenna arrays and measuring the corresponding Raman signal enhancement of individual CNTs. The results of the measurements are quantitatively discussed in light of numerical simulations which highlight the impact of the substrate.

cond-mat.mes-hall↗

Opening Scholarly Communication in Social Sciences by Connecting Collaborative Authoring to Peer Review

The objective of the OSCOSS research project on "Opening Scholarly Communication in the Social Sciences" is to build a coherent collaboration environment that facilitates scholarly communication workflows of social scientists in the roles of authors, reviewers, editors and readers. This paper presents the implementation of the core of this environment: the integration of the Fidus Writer academic word processor with the Open Journal Systems (OJS) submission and review management system.

cs.DL↗

A Semi-Automatic Approach for Detecting Dataset References in Social Science Texts

Today, full-texts of scientific articles are often stored in different locations than the used datasets. Dataset registries aim at a closer integration by making datasets citable but authors typically refer to datasets using inconsistent abbreviations and heterogeneous metadata (e.g. title, publication year). It is thus hard to reproduce research results, to access datasets for further analysis, and to determine the impact of a dataset. Manually detecting references to datasets in scientific articles is time-consuming and requires expert knowledge in the underlying research domain.We propose and evaluate a semi-automatic three-step approach for finding explicit references to datasets in social sciences articles.We first extract pre-defined special features from dataset titles in the da|ra registry, then detect references to datasets using the extracted features, and finally match the references found with corresponding dataset titles. The approach does not require a corpus of articles (avoiding the cold start problem) and performs well on a test corpus. We achieved an F-measure of 0.84 for detecting references in full-texts and an F-measure of 0.83 for finding correct matches of detected references in the da|ra dataset registry.

cs.DL↗

An Introduction to Mechanized Reasoning

Mechanized reasoning uses computers to verify proofs and to help discover new theorems. Computer scientists have applied mechanized reasoning to economic problems but -- to date -- this work has not yet been properly presented in economics journals. We introduce mechanized reasoning to economists in three ways. First, we introduce mechanized reasoning in general, describing both the techniques and their successful applications. Second, we explain how mechanized reasoning has been applied to economic problems, concentrating on the two domains that have attracted the most attention: social choice theory and auction theory. Finally, we present a detailed example of mechanized reasoning in practice by means of a proof of Vickrey's familiar theorem on second-price auctions.

cs.LO↗

LITMUS: An Open Extensible Framework for Benchmarking RDF Data Management Solutions

Developments in the context of Open, Big, and Linked Data have led to an enormous growth of structured data on the Web. To keep up with the pace of efficient consumption and management of the data at this rate, many data Management solutions have been developed for specific tasks and applications. We present LITMUS, a framework for benchmarking data management solutions. LITMUS goes beyond classical storage benchmarking frameworks by allowing for analysing the performance of frameworks across query languages. In this position paper we present the conceptual architecture of LITMUS as well as the considerations that led to this architecture.

cs.PF↗