1,532 research outputs found
Telegram from Hilda B. Weinert to Minnie Meacham Carter
No full textTelegram from Hilda B. Weinert to Minnie Meacham Carter upon the death of Amon Giles Carter. The telegram expresses condolences about his death.https://mavmatrix.uta.edu/specialcollections_meachamcarterpapers/1346/thumbnail.jp
Expertise zur Erfassung von psychologischen Personmerkmalen bei Kindern im Alter von fünf Jahren im Rahmen des SOEP
No full textSabine Weinert (Koord.) ; Jens B. Asendorpf ; Andreas Beelmann ; Hildegard Doil ; Sabine Frevert ; Arnold Lohaus ; Marcus Hasselhor
PSYNDEX Tests Review für CPI - CALIFORNIA PSYCHOLOGICAL INVENTORY - DEUTSCHE FASSUNG
No full textThis is a PSYNDEX Tests Review of CPI - CALIFORNIA PSYCHOLOGICAL INVENTORY - DEUTSCHE FASSUNG. PSYNDEX Tests Reviews are written in German and describe and evaluate psychological and educational tests used in the German-speaking countries. PSYNDEX Tests is offered by the Leibniz Institute for Psychology as open access documentation.Das ist ein PSYNDEX Tests Review zu CPI - CALIFORNIA PSYCHOLOGICAL INVENTORY - DEUTSCHE FASSUNG. PSYNDEX Tests Reviews beschreiben und bewerten zentrale psychologische und pädagogische Testverfahren, die in den deutschsprachigen Ländern eingesetzt werden, nach einem standardisierten Raster. PSYNDEX Tests wird durch das Leibniz-Institut für Psychologie als Open Access Dokumentation angeboten.publishedVersio
Optical fluid and biomolecule transport with thermal fields
No full textA long standing goal is the direct optical control of biomolecules and water for applications ranging from microfluidics over biomolecule detection to non-equilibrium biophysics. Thermal forces originating from optically applied, dynamic microscale temperature gradients have shown to possess great potential to reach this goal. It was demonstrated that laser heating by a few Kelvin can generate and guide water flow on the micrometre scale in bulk fluid, gel matrices or ice without requiring any lithographic structuring. Biomolecules on the other hand can be transported by thermal gradients, a mechanism termed thermophoresis, thermal diffusion or Soret effect. This molecule transport is the subject of current research, however it can be used to both characterize biomolecules and to record binding curves of important biological binding reactions, even in their native matrix of blood serum. Interestingly, thermophoresis can be easily combined with the optothermal fluid control. As a result, molecule traps can be created in a variety of geometries, enabling the trapping of small biomolecules, like for example very short DNA molecules. The combination with DNA replication from thermal convection allows us to approach molecular evolution with concurrent replication and selection processes inside a single chamber: replication is driven by thermal convection and selection by the concurrent accumulation of the DNA molecules. From the short but intense history of applying thermal fields to control fluid flow and biological molecules, we infer that many unexpected and highly synergistic effects and applications are likely to be explored in the future
Parity games with weights
No full textQuantitative extensions of parity games have recently attracted significant interest. These extensions include parity games with energy and payoff conditions as well as finitary parity games and their generalization to parity games with costs. Finitary parity games enjoy a special status among these extensions, as they offer a native combination of the qualitative and quantitative aspects in infinite games: The quantitative aspect of finitary parity games is a quality measure for the qualitative aspect, as it measures the limit superior of the time it takes to answer an odd color by a larger even one. Finitary parity games have been extended to parity games with costs, where each transition is labeled with a nonnegative weight that reacts the costs incurred by taking it. We lift this restriction and consider parity games with costs with arbitrary integer weights. We show that solving such games is in NP ∩ co-NP, the signature complexity for games of this type. We also show that the protagonist has finite-state winning strategies, and provide tight pseudo-polynomial bounds for the memory he needs to win the game. Naturally, the antagonist may need infinite memory to win. Moreover, we present tight bounds on the quality of winning strategies for the protagonist. Furthermore, we investigate the problem of determining, for a given threshold b, whether the protagonist has a strategy of quality at most b and show this problem to be ExpTime complete. The protagonist inherits the necessity of exponential memory for implementing such strategies from the special case of finitary parity games
The Past-Future Asymmetry
No full textAs the past-future asymmetry – that fact that we have records of the past but not the future – is still a puzzle the aim of this paper is twofold: a) to explain the asymmetry and its status in philosophy and physics and to critically review the proposed solutions to this puzzle; b) to advance a dynamic solution to the puzzle (which is lacking in alternative proposals) in terms of the ‘universality’ of the entropy relation in statistical mechanics
Temporal Arrows in Space-Time
No full textThe prevailing current of thought in both physics and philosophy is that
relativistic space-time provides no means for the objective measurement of the passage of time. Kurt Gödel, for instance, denied the possibility of an objective lapse of time, both in the Special and the General theory of
relativity. From this failure many writers have inferred that a static block universe is the only acceptable conceptual consequence of a four-dimensional world. The aim of this paper is to investigate how arrows of time
could be measured objectively in space-time. In order to carry out this investigation it is proposed to consider both local and global arrows of time. In particular the investigation will focus on a) in variant thermodynamic
parameters in both the Special and the General theory for local regions of space-time (passage of time); b) the evolution of the universe under appropriate boundary conditions for the whole of space-time (arrow of time,as envisaged in modern quantum cosmology. The upshot of this
investigation is that a number of invariant physical indicators in space-time can be found, which would allow observers to measure the lapse of time and to infer both the existence of an objective passage and an arrow of time
Practical Private Set Intersection Protocols for Privacy-Preserving Applications
No full textPrivate set intersection (PSI) protocols are cryptographic protocols that allow two parties to securely compute the intersection of their private input sets without disclosing elements outside of the intersection. While this simple functionality turns out to be instrumental for many real-world applications, existing protocol designs and implementations unfortunately incur an impractical computation and/or communication overhead. As a consequence, service providers currently deploy insecure alternatives that threaten users' privacy at a large scale.
Therefore, in this thesis, we design, implement, and evaluate practical PSI protocols to provide viable privacy-preserving alternatives for three specific application scenarios: mobile contact discovery, mutual authentication for Apple AirDrop, and database intersection analytics.
Mobile Contact Discovery. Mobile messengers commonly offer a feature that allows users to discover their existing contacts on the platform based on the phone numbers stored in their address book. Unfortunately, we find that popular messengers implement contact discovery either by uploading the users' entire address books in the clear or by using simple hashing-based protocols. As we show that such hashing-based protocols are vulnerable to brute-force attacks, the users' entire social graphs are exposed to anyone with access to the service providers' infrastructure. To instead perform the matching procedure between address books and user databases in a privacy-preserving manner, we develop and optimize two PSI protocols that are significantly more efficient than the state-of-the-art protocols of Kiss et al. (PoPETs'17) while also providing security against malicious clients.
By closely investigating the contact discovery implementation of three popular messengers (WhatsApp, Telegram, and Signal), we also find that due to insufficient rate limits, attackers can crawl the global user databases simply by enumerating phone numbers. For this problem, we propose multiple mitigation techniques, including a novel PSI-compatible rate-limiting scheme that strictly improves over the approach currently deployed by Signal.
This part of the thesis is based on the following two publications:
[KRS+19] D. KALES, C. RECHBERGER, T. SCHNEIDER, M. SENKER, C. WEINERT. "Mobile Private Contact Discovery at Scale". In: 28. USENIX Security Symposium (USENIX Security'19). Website: https://contact-discovery.github.io. Full version: https://ia.cr/2019/517. USENIX Association, 2019, pp. 1447–1464. CORE Rank A*. Appendix B.
[HWS+21] C. HAGEN, C. WEINERT, C. SENDNER, A. DMITRIENKO, T. SCHNEIDER. "All the Numbers are US: Large-scale Abuse of Contact Discovery in Mobile Messengers". In: 28. Network and Distributed System Security Symposium (NDSS'21). Website: https://contact-discovery.github.io. Full version: https://ia.cr/2020/1119. Internet Society, 2021. CORE Rank A*. Appendix A.
Mutual Authentication for Apple AirDrop. Based on the reverse-engineering efforts of Stute et al. (USENIX Security'19), we identify two privacy vulnerabilities in Apple's proprietary offline file sharing service AirDrop. They are rooted in the exchange of vulnerable hash values of contact identifiers during the authentication handshake that determines whether two device owners are mutual contacts. We demonstrate both attacks with a proof-of-concept implementation called "AirCollect" that can almost instantly recover the mobile phone numbers of nearby Apple users who open the sharing pane on their devices.
As a privacy-preserving alternative, we develop "PrivateDrop". Our solution is based on two consecutive executions of optimized PSI protocols that provide security against malicious parties and additionally enforce authentic inputs. We implement PrivateDrop in Apple's native programming language Swift and show in an empirical performance evaluation on real Apple devices that the overall authentication delay of below one second preserves the user experience of the original insecure AirDrop protocol.
This part of the thesis is based on the following two publications:
[HHS+21a] A. HEINRICH, M. HOLLICK, T. SCHNEIDER, M. STUTE, C. WEINERT. "DEMO: AirCollect: Efficiently Recovering Hashed Phone Numbers Leaked via Apple AirDrop". In: 14. ACM Conference on Security and Privacy in Wireless and Mobile Networks (WiSec'21). Website: https://privatedrop.github.io. Full version: https://ia.cr/2021/893. ACM, 2021, pp. 371–373. Appendix C.
[HHS+21b] A. HEINRICH, M. HOLLICK, T. SCHNEIDER, M. STUTE, C. WEINERT. "PrivateDrop: Practical Privacy-Preserving Authentication for Apple AirDrop". In: 30. USENIX Security Symposium (USENIX Security'21). Website: https://privatedrop.github.io. Full version: https://ia.cr/2021/481. USENIX Association, 2021, pp. 3577–3594. CORE Rank A*. Appendix D.
Database Intersection Analytics. Scenarios where two companies or governmental agencies want to conduct analyses on data subjects they have in common without revealing their entire database are usually addressed with generic circuit-based PSI protocols that can compute arbitrary functions of the database intersection. The best prior circuit-based PSI protocols of Pinkas et al. (USENIX Security'15 and ACM TOPS'18) have a complexity of O(n log n/ log log n), where n is the number of database entries. In our work, we create the first circuit-based PSI protocol with almost linear ω(n) complexity that also significantly outperforms prior works in terms of concrete performance. Our construction is based on a novel hashing scheme called "2D Cuckoo hashing", which we analyze experimentally by spending millions of core hours on a high-performance computer.
This part of the thesis is based on the following publication:
[PSWW18] B. PINKAS, T. SCHNEIDER, C. WEINERT, U. WIEDER. "Efficient Circuit-Based PSI via Cuckoo Hashing". In: 37. Advances in Cryptology – EUROCRYPT'18. Vol. 10822. LNCS. Code: https://encrypto.de/code/2DCH. Full version: https://ia.cr/2018/120. Springer, 2018, pp. 125–157. CORE Rank A*. Appendix E.
Overall, this thesis contributes to make private set intersection protocols sufficiently practical to provide privacy-preserving solutions for three widely-used real-world applications
Metabolomanalysen von Tomaten mittels GCxGC/MS: Ein Werkzeug für Qualitätssicherung und Züchtung
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