114612 research outputs found
Sort by
Crystal growth of ternary metal sulfides from an open melt: Ba 2 MnS 3 †
No full textWe present the growth and characterization of sizable single crystals of the transition metal sulfide Ba2MnS3 by the floating-zone technique. Notably, to the best of our knowledge, this method marks the first instance of sulfide melt growth in an open atmosphere, prompting us to detail modifications to our halogen image furnace to eliminate oxygen from the growth atmosphere. This advance is expected to prove valuable for cultivating substantial crystals of other sulfide materials. We present a detailed study of Ba2MnS3. Through single crystal X-ray and neutron diffraction, we confirm Ba2MnS3 adopts the orthorhombic space group Pnma with unit cell parameters of a = 8.88960 (10) Å, b = 4.33630 (10) Å, c = 17.2210 (2) Å, and V = 663.835 (19) Å3 at 300 K. By means of magnetometry and specific heat capacity, we identify an antiferromagnetic ground state, with two transitions at 19.6 and 21.1 K. Finally, we elucidate the magnetic ground state through single crystal neutron diffraction, demonstrating the system is described by the magnetic propagation vector k = (0, 1/2, 0) and belongs to the Pb21/n magnetic space group
Variation in follow-up for children born very preterm in Europe
Get PDFBackground:
Children born very preterm (<32 weeks of gestation) face high risks of neurodevelopmental and health difficulties compared with children born at term. Follow-up after discharge from the neonatal intensive care unit is essential to ensure early detection and intervention, but data on policy approaches are sparse.
Methods:
We investigated the characteristics of follow-up policy and programmes in 11 European countries from 2011 to 2022 using healthcare informant questionnaires and the published/grey literature. We further explored how one aspect of follow-up, its recommended duration, may be reflected in the percent of parents reporting that their children are receiving follow-up services at 5 years of age in these countries using data from an area-based cohort of very preterm births in 2011/12 (N = 3635).
Results:
Between 2011/12 and 22, the number of countries with follow-up policies or programmes increased from 6 to 11. The policies and programmes were heterogeneous in eligibility criteria, duration and content. In countries that recommended longer follow-up, parent-reported follow-up rates at 5 years of age were higher, especially among the highest risk children, born <28 weeks’ gestation or with birthweight <1000 g: between 42.1% and 70.1%, vs. <20% in most countries without recommendations.
Conclusions:
Large variations exist in follow-up policies and programmes for children born very preterm in Europe; differences in recommended duration translate into cross-country disparities in reported follow-up at 5 years of age
Fixed-parameter debordering of Waring rank
Get PDFBorder complexity measures are defined via limits (or topological closures), so that any function which can approximated arbitrarily closely by low complexity functions itself has low border complexity. Debordering is the task of proving an upper bound on some non-border complexity measure in terms of a border complexity measure, thus getting rid of limits.
Debordering is at the heart of understanding the difference between Valiant's determinant vs permanent conjecture, and Mulmuley and Sohoni's variation which uses border determinantal complexity. The debordering of matrix multiplication tensors by Bini played a pivotal role in the development of efficient matrix multiplication algorithms. Consequently, debordering finds applications in both establishing computational complexity lower bounds and facilitating algorithm design. Currently, very few debordering results are known.
In this work, we study the question of debordering the border Waring rank of polynomials. Waring and border Waring rank are very well studied measures in the context of invariant theory, algebraic geometry, and matrix multiplication algorithms. For the first time, we obtain a Waring rank upper bound that is exponential in the border Waring rank and only linear in the degree. All previous known results were exponential in the degree. For polynomials with constant border Waring rank, our results imply an upper bound on the Waring rank linear in degree, which previously was only known for polynomials with border Waring rank at most 5
Study of hot deformation behavior of EN25 steel in the presence of non-metallic inclusions
No full textThe Gleeble® simulator 3800 has been used to study the hot deformation behavior of EN25B steel in the presence of inclusions. The experimental flow stress values are analyzed to generate the processing map, which identified the safe deformation zone at two true strain levels with maximum of 50% deformation. At a comparatively lower true strain of 0.4, the safe zone locates in the high-temperature (1050 to 1150 °C) and high-strain-rate regime (2.5 to10 s−1). At higher strain (0.69), the safe zone moves to further right to a higher-temperature zone (1070-1150 °C) but extends further to lower strain rates (1.25 to 10 s−1). The amount of dynamically recrystallized grains was estimated under various deformation conditions, and it decreased with a decrease in temperature, irrespective of strain rates. The investigation of non-metallic inclusions (NMIs) was conducted via electrolytic extraction, followed by SEM and XCT examination. Inclusion size estimated by XCT analysis of electrolytically extracted inclusions on paper was found to be more accurate and ~ 50% higher than SEM analysis on the surface of the sample. At high strain rates and temperatures, the outcomes demonstrated the existence of harmless finer inclusions, validating the location of the safe zone. Additionally, a constitutive model for flow stress in steel of grade EN25 has been created
Peptidoglycan synthesis drives a single population of septal cell wall synthases during division in Bacillus subtilis
Get PDFBacterial cell division requires septal peptidoglycan (sPG) synthesis by the divisome complex. Treadmilling of the essential tubulin homologue FtsZ has been implicated in septal constriction, though its precise role remains unclear. Here we used live-cell single-molecule imaging of the divisome transpeptidase PBP2B to investigate sPG synthesis dynamics in Bacillus subtilis. In contrast to previous models, we observed a single population of processively moving PBP2B molecules whose motion is driven by peptidoglycan synthesis and is not associated with FtsZ treadmilling. However, despite the asynchronous motions of PBP2B and FtsZ, a partial dependence of PBP2B processivity on FtsZ treadmilling was observed. Additionally, through single-molecule counting experiments we provide evidence that the divisome synthesis complex is multimeric. Our results support a model for B. subtilis division where a multimeric synthesis complex follows a single track dependent on sPG synthesis whose activity and dynamics are asynchronous with FtsZ treadmilling
Trustworthiness assurance assessment for high-risk AI-based systems
Get PDFThis work proposes methodologies for ensuring the trustworthiness of high-risk artificial
intelligence (AI) systems (AIS) to achieve compliance with the European Union’s (EU) AI Act. Highrisk classified AIS must fulfill seven requirements to be considered trustworthy and human-centric, and
subsequently be considered for deployment. These requirements are equally important, mutually supportive,
and should be implemented and evaluated throughout the AI lifecycle. The assurance of trustworthiness is
influenced by ethical considerations, amongst others. Hence, the operational design domain (ODD) and
behavior competency (BC) concepts from the automated driving domain are utilized in risk assessment
strategies to quantify different types of residual risks. The methodology presented is guided by the consistent
application of the ODD and its related BC concept throughout the entire AI lifecycle, focusing on the
trustworthiness assurance framework and its associated process as the main pillars for AIS certification.
The achievement of the overall objective of trustworthy and human-centric AIS is divided into seven
interconnected sub-goals: the formulation of use restrictions, the trustworthiness assurance/argument itself,
the identification of dysfunctional cases, the utilization of scenario This work proposes methodologies for ensuring the trustworthiness of high-risk artificial intelligence (AI) systems (AIS) to achieve compliance with the European Union’s (EU) AI Act. High-risk classified AIS must fulfill seven requirements to be considered trustworthy and human-centric, and subsequently be considered for deployment. These requirements are equally important, mutually supportive, and should be implemented and evaluated throughout the AI lifecycle. The assurance of trustworthiness is influenced by ethical considerations, amongst others. Hence, the operational design domain (ODD) and behavior competency (BC) concepts from the automated driving domain are utilized in risk assessment strategies to quantify different types of residual risks. The methodology presented is guided by the consistent application of the ODD and its related BC concept throughout the entire AI lifecycle, focusing on the trustworthiness assurance framework and its associated process as the main pillars for AIS certification. The achievement of the overall objective of trustworthy and human-centric AIS is divided into seven interconnected sub-goals: the formulation of use restrictions, the trustworthiness assurance/argument itself, the identification of dysfunctional cases, the utilization of scenario databases and datasets, the application of metrics for evaluation, the implementation of the proposed concept across the AI lifecycle, and sufficient consideration of human factors. The role of standards in the assurance process is discussed, considering any existing gaps and areas for improvement. The work concludes with a summary of the developed approach, highlighting key takeaways and action points. Finally, a roadmap to ensure trustworthy and human-centric behavior of future AIS is outlined
Persistence of spectral projections for stochastic operators on large tensor products
No full textIt is proved that for families of stochastic operators on a countable tensor product, depending smoothly on parameters, any spectral projection persists smoothly, where smoothness is defined using norms based on ideas of Dobrushin. A rigorous perturbation theory for families of stochastic operators with spectral gap is thereby created. It is illustrated by deriving an effective slow two-state dynamics for a three-state probabilistic cellular automaton
Hierarchical neural simulation-based inference over event ensembles
Get PDFWhen analyzing real-world data it is common to work with event ensembles, which comprise sets of observations that collectively constrain the parameters of an underlying model of interest. Such models often have a hierarchical structure, where ``local'' parameters impact individual events and ``global'' parameters influence the entire dataset. We introduce practical approaches for frequentist and Bayesian dataset-wide probabilistic inference in cases where the likelihood is intractable, but simulations can be realized via a hierarchical forward model. We construct neural estimators for the likelihood(-ratio) or posterior and show that explicitly accounting for the model's hierarchical structure can lead to significantly tighter parameter constraints. We ground our discussion using case studies from the physical sciences, focusing on examples from particle physics and cosmology
The aesthetics of sovereignty
No full textSovereignty is commonly understood to involve the co-ordination of two forms of power: auctoritas (the power of legitimate authority) and potestas (the power of effective rule). In this chapter I argue that this conception of sovereignty – understood, put crudely, as the interweaving of right and might – misses a third, and essentially important, aspect of the concept: its aesthetics. Whilst we commonly associate aesthetics with theories of the beautiful or with studies of artistic practices, aesthetics also refers to the nature of our sense perception, in the widest terms. In this way, aesthetics refers to material, socio-cultural dimensions that are seen, sensed, felt and experienced. The aesthetics of sovereignty, then, refers to the processes through which the concepts, institutions, beliefs and practices which constitute sovereignty render subjects sensitive or insensitive to material and social relations. Through the introduction of three related modalities of sovereignty’s aesthetics: representation, appearance, and imaginary, the chapter argues that an analytic priority should be afforded to the aesthetic dimensions of sovereignty because it is within the aesthetic, affective and imaginative registers that social and material relations are first visualised, represented, felt and given sense before they are expressed in legal and political terms