227 research outputs found
Inferring Regulatory Networks by Combining Perturbation Screens and Steady State Gene Expression Profiles
Reconstructing transcriptional regulatory networks is an important task in
functional genomics. Data obtained from experiments that perturb genes by
knockouts or RNA interference contain useful information for addressing this
reconstruction problem. However, such data can be limited in size and/or are
expensive to acquire. On the other hand, observational data of the organism in
steady state (e.g. wild-type) are more readily available, but their
informational content is inadequate for the task at hand. We develop a
computational approach to appropriately utilize both data sources for
estimating a regulatory network. The proposed approach is based on a three-step
algorithm to estimate the underlying directed but cyclic network, that uses as
input both perturbation screens and steady state gene expression data. In the
first step, the algorithm determines causal orderings of the genes that are
consistent with the perturbation data, by combining an exhaustive search method
with a fast heuristic that in turn couples a Monte Carlo technique with a fast
search algorithm. In the second step, for each obtained causal ordering, a
regulatory network is estimated using a penalized likelihood based method,
while in the third step a consensus network is constructed from the highest
scored ones. Extensive computational experiments show that the algorithm
performs well in reconstructing the underlying network and clearly outperforms
competing approaches that rely only on a single data source. Further, it is
established that the algorithm produces a consistent estimate of the regulatory
network.Comment: 24 pages, 4 figures, 6 table
Life cycle assessment of recycling options for automotive Li-ion battery packs
Ramping up automotive lithium-ion battery (LIB) production volumes creates an imperative need for the establishment of end-of-life treatment chains for spent automotive traction battery packs. Life Cycle Assessment (LCA) is an essential tool in evaluating the environmental performance of such chains and options. This work synthesises publicly-available data to expand upon previously reported LCA studies for LIB recycling and holistically model end-of-life treatment chains for spent automotive traction battery packs with lithium nickel cobalt manganese oxide positive electrodes. The study provides an in-depth analysis of unit process contributions to the environmental benefits and burdens of battery recycling options and integrates these with the battery production impacts to estimate the net environmental benefit achieved by the introduction of recycling in the value chain. The attributional LCA model accounts for the whole recycling chain, from the point of end-of-life LIB collection to the provision of secondary materials for battery manufacturing. Pyrometallurgical processing of spent automotive traction battery cells is predicted to have a larger Global Warming Potential (GWP), due to its higher energy intensity, while hydrometallurgical processing is shown to be more environmentally beneficial, due to the additional recovery of lithium as hydroxide. The majority of the environmental benefits arise from the recovery of aluminium and copper fractions of battery packs, with important contributions also arising from the recovery of nickel and cobalt from the battery cells. Overall, the LCA model presented estimates a net benefit in 11 out of 13 environmental impact categories based on the ReCiPe characterisation method, as compared to battery production without recycling. An investigation of the effect of geographic specificity on the combined production and recycling indicates that it is as a key source of GWP impact variability and that the more climate burdening chains offer a significantly higher potential for GWP reductions through battery recycling. The sensitivity analysis carried out shows that impacts related to air quality are higher when recovering lower grade materials. This study provides a quantitative and replicable inventory model which highlights the significance of the environmental benefits achieved through the establishment of circular automotive battery value chains
Cloud Watching: Understanding Attacks Against Cloud-Hosted Services
Cloud computing has dramatically changed service deployment patterns. In this
work, we analyze how attackers identify and target cloud services in contrast
to traditional enterprise networks and network telescopes. Using a diverse set
of cloud honeypots in 5~providers and 23~countries as well as 2~educational
networks and 1~network telescope, we analyze how IP address assignment,
geography, network, and service-port selection, influence what services are
targeted in the cloud. We find that scanners that target cloud compute are
selective: they avoid scanning networks without legitimate services and they
discriminate between geographic regions. Further, attackers mine
Internet-service search engines to find exploitable services and, in some
cases, they avoid targeting IANA-assigned protocols, causing researchers to
misclassify at least 15\% of traffic on select ports. Based on our results, we
derive recommendations for researchers and operators.Comment: Proceedings of the 2023 ACM Internet Measurement Conference (IMC
'23), October 24--26, 2023, Montreal, QC, Canad
Detection of Sparse Anomalies in High-Dimensional Network Telescope Signals
Network operators and system administrators are increasingly overwhelmed with
incessant cyber-security threats ranging from malicious network reconnaissance
to attacks such as distributed denial of service and data breaches. A large
number of these attacks could be prevented if the network operators were better
equipped with threat intelligence information that would allow them to block or
throttle nefarious scanning activities. Network telescopes or "darknets" offer
a unique window into observing Internet-wide scanners and other malicious
entities, and they could offer early warning signals to operators that would be
critical for infrastructure protection and/or attack mitigation. A network
telescope consists of unused or "dark" IP spaces that serve no users, and
solely passively observes any Internet traffic destined to the "telescope
sensor" in an attempt to record ubiquitous network scanners, malware that
forage for vulnerable devices, and other dubious activities. Hence, monitoring
network telescopes for timely detection of coordinated and heavy scanning
activities is an important, albeit challenging, task. The challenges mainly
arise due to the non-stationarity and the dynamic nature of Internet traffic
and, more importantly, the fact that one needs to monitor high-dimensional
signals (e.g., all TCP/UDP ports) to search for "sparse" anomalies. We propose
statistical methods to address both challenges in an efficient and "online"
manner; our work is validated both with synthetic data as well as real-world
data from a large network telescope
(Homo-)Sexuelle Lust jenseits der Metropole
Bereits seit Jahrzehnten beschweren sich queere Aachener_innen darüber, dass ihnen die lebendigere Subkultur der 1980er und 1990er Jahre fehle. Die wenigen queeren Räume in der Innenstadt sind heute institutionalisiert und konzentrieren sich meist auf soziale Arbeit oder ehrenamtliches Engagement – distanziert von Elementen der Lust und sexueller Begegnung. In den vergangenen 50 Jahren lassen sich jedoch zahlreiche Beispiele für Raumproduktionen finden, die auf eine belebte Klappenkultur und eine Sexualisierung von Räumen hinweisen. In Parkanlagen, öffentlichen Toiletten auf Bahnhöfen oder in Hochschulgebäuden sowie über Dating-Apps haben Männer, die Sex mit anderen Männern suchten, trotz – oder gerade wegen des erzkatholischen Glaubens in der Stadt Aachen – immer wieder neue Cruising-Orte für sich kreieren können. Die Schaffung dieser Räume, die Verbreitung des Wissens über sie, ihre Nutzung – der gesamte Prozess um das cruising herum war in Aachen, ebenso wie in vielen anderen (Groß-)Städten, aufgrund gesetzlicher Regelungen und sozialer Normen jahrzehntelang versteckt, tabuisiert, schambehaftet und geächtet. Dieser Beitrag deckt diese (zumindest für die Mehrheitsgesellschaft) verborgene und unbekannte Welt der Aachener Klappen-Kultur auf. Der Artikel stützt sich auf Archivrecherchen und Interviews mit queeren Zeitzeugen verschiedener Generationen. Diese kombinierte Methodik bietet Einblicke in die Vergangenheit, Gegenwart und erwartete Zukunft von Aachens intimen Raumproduktionen. Ziel dieser Untersuchung ist es, queere sexuelle Lust in einer Stadt außerhalb des deutschen LSBTIQ+-Mainstreams zu kartieren, sichtbar zu machen und über seine Entwicklung innerhalb des vergangenen halben Jahrhunderts zu reflektieren
Environmental life cycle assessment of Mediterranean sea bass and sea bream
The aquaculture sector is the fastest growing food production industry, with sea bass and sea bream consisting important exporting goods in the Mediterranean region. This work presents results of a life cycle assessment of Mediterranean sea bass and sea bream, based on primary data collected from a Greek producer. The system boundary included fish feed production and the rearing operation, as well as the packaging and delivery processes, which were neglected in preceding literature studies. The life cycle inventory developed addressed previous data gaps in the production of Mediterranean aquaculture species. Comparison to preceding studies revealed differences on the production inventories and identified methodological choices leading to variability. Packaging and delivery processes were found to contribute approximately 40% towards the global warming score. The production of both sea bass and sea bream was shown to come with high eutrophication impacts occurring from the rearing stage. The feed production was identified as the most environmental impact intensive process throughout the life cycle. Sea bass came with lower environmental impacts per unit live mass, which was reversed when the species were compared on a protein basis. The replicable and transparent model presented here, contributes towards the more accurate quantification of the environmental impacts associated with Mediterranean aquaculture species and supports efforts aiming to promote environmental protection through dietary change
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