865 research outputs found
The toxicity of cadmium and resulting hazards for human health
Cadmium (Cd) has been in industrial use for a long period of time. Its serious toxicity moved into scientific focus during the middle of the last century. In this review, we discuss historic and recent developments of toxicological and epidemiological questions, including exposition sources, resorption pathways and organ damage processes
From scalar fields on quantum spaces to blobbed topological recursion
We review the construction of the -model on noncommutative
geometries via exact solutions of Dyson-Schwinger equations and explain how
this construction relates via (blobbed) topological recursion to problems in
algebraic and enumerative geometry.Comment: 33 pages, 9 figures. Contribution to "Noncommutativity in Physics"
(special volume initiated by CORFU2021
Similarity-based cooperative equilibrium
As machine learning agents act more autonomously in the world, they will
increasingly interact with each other. Unfortunately, in many social dilemmas
like the one-shot Prisoner's Dilemma, standard game theory predicts that ML
agents will fail to cooperate with each other. Prior work has shown that one
way to enable cooperative outcomes in the one-shot Prisoner's Dilemma is to
make the agents mutually transparent to each other, i.e., to allow them to
access one another's source code (Rubinstein 1998, Tennenholtz 2004) -- or
weights in the case of ML agents. However, full transparency is often
unrealistic, whereas partial transparency is commonplace. Moreover, it is
challenging for agents to learn their way to cooperation in the full
transparency setting. In this paper, we introduce a more realistic setting in
which agents only observe a single number indicating how similar they are to
each other. We prove that this allows for the same set of cooperative outcomes
as the full transparency setting. We also demonstrate experimentally that
cooperation can be learned using simple ML methods.Comment: Published at NeurIPS 2023. 32 pages, 9 figure
Geschäftsmodelle der Energiewende im regionalen Umfeld
Die Energiewende beeinflusst maßgeblich die Entwicklung energiewirtschaftlicher Wertschöpfung und Geschäftsmodelle. Diese Entwicklung betrifft auch und insbesondere den ländlichen Raum. Vor diesem Hintergrund wird in diesem Papier für die untersuchte „Modellregion Mecklenburg“ eine Bestandsaufnahme der energiewirtschaftlichen Wertschöpfungskette durchgeführt. Ferner wird eine Übertragbarkeit des Geschäftsmodell-Frameworks Energiewirtschaft zur Identifikation von Geschäftsmodellprototypen, d. h. einer Zusammenfassung gleichartiger Geschäftsmodelle, aus Giehl et al. (2020) aufgezeigt. Basierend hierauf werden regionale Wertschöpfungsnetzwerke entwickelt und analysiert, um hieraus in Verbindung mit dem Ansatz der Wertschöpfungscluster nach Porter (1991) Handlungsempfehlungen für die Untersuchungsregion abzuleiten
Anomaly-matching and Higgs-less effective theories
We reconsider the low-energy effective theory for Higgs-less electroweak
symmetry breaking: we study the anomaly-matching in the situation where all
Goldstone fields disappear from the spectrum as a result of the Higgs
mechanism. We find that the global SU(2)_L x SU(2)_R x U(1)_{B-L} symmetry of
the underlying theory, which is spontaneously broken to SU(2)_{L+R} x
U(1)_{B-L} has to be anomaly-free. For the sake of generality, we include the
possibility of light spin-1/2 bound states resulting from the dynamics of the
strongly-interacting symmetry-breaking sector, in addition to the Goldstone
bosons. Such composite fermions may have non-standard couplings at the leading
order, and an arbitrary total B-L charge. In order to perform the
anomaly-matching in that case, we generalize the construction of the
Wess-Zumino effective lagrangian. Composite fermions beyond the three known
generations are theoretically allowed, and there are no restrictions from the
anomaly-matching on their couplings nor on their U(1)_{B-L} charge. Absence of
global anomalies for the composite sector as a whole does not preclude
anomalous triple gauge boson couplings arising from composite fermion
triangular diagrams. On the other hand, the trace of B-L over elementary
fermions must vanish if all Goldstone modes are to disappear from the spectrum.Comment: Keywords: Anomalies in Field and String Theories, Spontaneous
Symmetry Breaking, Beyond the Standard Model, Chiral Lagrangians. 33 pages, 7
figure
Environmental impact of warehousing: a scenario analysis for the United States
In recent years, there has been observed a continued growth of global carbon dioxide emissions, which are considered as a crucial factor for the greenhouse effect and associated with substantial environmental damages. Amongst others, logistic activities in global supply chains have become a major cause of industrial emissions and the progressing environmental pollution. Although a significant amount of logistic-related carbon dioxide emissions is caused by storage and material handling processes in warehouses, prior research mostly focused on the transport elements. The environmental impact of warehousing has received only little attention by research so far. Operating large and highly technological warehouses, however, causes a significant amount of energy consumption due to lighting, heating, cooling and air condition as well as fixed and mobile material handling equipment which induces considerable carbon dioxide emissions. The aim of this paper is to summarise preliminary studies of warehouse-related emissions and to discuss an integrated classification scheme enabling researchers and practitioners to systematically assess the carbon footprint of warehouse operations. Based on the systematic assessment approach containing emissions determinants and aggregates, overall warehouse emissions as well as several strategies for reducing the carbon footprint will be studied at the country level using empirical data of the United States. In addition, a factorial analysis of the warehouse-related carbon dioxide emissions in the United States enables the estimation of future developments and facilitates valuable insights for identifying effective mitigation strategies
The Orphan Adhesion-GPCR GPR126 Is Required for Embryonic Development in the Mouse
Adhesion-GPCRs provide essential cell-cell and cell-matrix interactions in development, and have been implicated in inherited human diseases like Usher Syndrome and bilateral frontoparietal polymicrogyria. They are the second largest subfamily of seven-transmembrane spanning proteins in vertebrates, but the function of most of these receptors is still not understood. The orphan Adhesion-GPCR GPR126 has recently been shown to play an essential role in the myelination of peripheral nerves in zebrafish. In parallel, whole-genome association studies have implicated variation at the GPR126 locus as a determinant of body height in the human population. The physiological function of GPR126 in mammals is still unknown. We describe a targeted mutation of GPR126 in the mouse, and show that GPR126 is required for embryonic viability and cardiovascular development
Neuroevolution of Self-Interpretable Agents
Inattentional blindness is the psychological phenomenon that causes one to
miss things in plain sight. It is a consequence of the selective attention in
perception that lets us remain focused on important parts of our world without
distraction from irrelevant details. Motivated by selective attention, we study
the properties of artificial agents that perceive the world through the lens of
a self-attention bottleneck. By constraining access to only a small fraction of
the visual input, we show that their policies are directly interpretable in
pixel space. We find neuroevolution ideal for training self-attention
architectures for vision-based reinforcement learning (RL) tasks, allowing us
to incorporate modules that can include discrete, non-differentiable operations
which are useful for our agent. We argue that self-attention has similar
properties as indirect encoding, in the sense that large implicit weight
matrices are generated from a small number of key-query parameters, thus
enabling our agent to solve challenging vision based tasks with at least 1000x
fewer parameters than existing methods. Since our agent attends to only task
critical visual hints, they are able to generalize to environments where task
irrelevant elements are modified while conventional methods fail. Videos of our
results and source code available at https://attentionagent.github.io/Comment: To appear at the Genetic and Evolutionary Computation Conference
(GECCO 2020) as a full pape
Earthquake forecasting in Italy, before and after Umbria-Marche seismic sequence 1997. A review of the earthquake occurrence modeling at different spatio-temporal-magnitude scales.
The main goal of this work is to review the scientific researches carried out before and after the Umbria-Marche sequence related to the earthquake forecasting/prediction in Italy. In particular, I focus the attention on models that aim addressing three main practical questions: was (is) Umbria-Marche a region with high probability of occurrence of a destructive earthquake? Was a precursory activity recorded before the mainshock(s)? What was our capability to model the spatio-temporal-magnitude evolution of that seismic sequence? The models are reviewed pointing out what we have learned after the Umbria-Marche earthquakes, in terms of physical understanding of earthquake occurrence process, and of improving our capability to forecast earthquakes and to track in real-time seismic sequences
Causes and Consequences of A Glutamine Induced Normoxic HIF1 Activity for the Tumor Metabolism
The transcription factor hypoxia-inducible factor 1 (HIF1) is the crucial regulator of
genes that are involved in metabolism under hypoxic conditions, but information regarding the
transcriptional activity of HIF1 in normoxic metabolism is limited. Different tumor cells were treated
under normoxic and hypoxic conditions with various drugs that affect cellular metabolism. HIF1ff
was silenced by siRNA in normoxic/hypoxic tumor cells, before RNA sequencing and bioinformatics
analyses were performed while using the breast cancer cell line MDA-MB-231 as a model. Differentially
expressed genes were further analyzed and validated by qPCR, while the activity of the metabolites
was determined by enzyme assays. Under normoxic conditions, HIF1 activity was significantly
increased by (i) glutamine metabolism, which was associated with the release of ammonium, and
it was decreased by (ii) acetylation via acetyl CoA synthetase (ACSS2) or ATP citrate lyase (ACLY), respectively, and (iii) the presence of L-ascorbic acid, citrate, or acetyl-CoA. Interestingly, acetylsalicylic
acid, ibuprofen, L-ascorbic acid, and citrate each significantly destabilized HIF1ff only under normoxia.
The results from the deep sequence analyses indicated that, in HIF1-siRNA silenced MDA-MB-231
cells, 231 genes under normoxia and 1384 genes under hypoxia were transcriptionally significant
deregulated in a HIF1-dependent manner. Focusing on glycolysis genes, it was confirmed that HIF1
significantly regulated six normoxic and 16 hypoxic glycolysis-associated gene transcripts. However,
the results from the targeted metabolome analyses revealed that HIF1 activity affected neither the
consumption of glucose nor the release of ammonium or lactate; however, it significantly inhibited
the release of the amino acid alanine. This study comprehensively investigated, for the first time,
how normoxic HIF1 is stabilized, and it analyzed the possible function of normoxic HIF1 in the
transcriptome and metabolic processes of tumor cells in a breast cancer cell model. Furthermore, these
data imply that HIF1 compensates for the metabolic outcomes of glutaminolysis and, subsequently,
theWarburg effect might be a direct consequence of the altered amino acid metabolism in tumor cells
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