bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact cratering record of Sweden—A review
Authors: Holm-Alwmark* Sanna 
Published: June 2021

ABSTRACT
Studies of impact structures in Sweden date back almost 60 years. They have so far resulted in the confirmation and understanding of eight impact structures and one impact-derived breccia layer, including the largest confirmed impact structure in the western part of Europe, the Siljan impact structure. Several additional structures have been proposed as impact derived, but they have to date not been confirmed.
In this contribution, I summarize the current state of knowledge about the impact cratering record of Sweden. This is an up-to-date, comprehensive review of the features of known impact structures (and impact-related deposits) in Sweden. The described impact structures formed over a time period spanning from the Cambrian to the Cretaceous, and the preservation of several small (~1–2 km in diameter) Paleozoic impact structures indicates that the conditions securing their protection were close to optimal, with formation in a shallow epicontinental sea and rapid cover by protective sediments followed by a regional geologic evolution permitting their preservation. The generally well-preserved state of some of these crater structures contradicts the general assumption that such small impact structures can only be preserved for approximately a couple of thousand to a few million years.
The Lockne-Målingen, Tvären, Granby, and Hummeln impact structures all have ages that place their formation in a period of proposed increased cratering rate on Earth following the breakup event of the L-chondrite parent body in the asteroid belt. However, to date, evidence other than a temporal correlation is missing for all of these structures except for Lockne (and Målingen), which has been shown to have formed by the impact of an L-chondritic body.
The Cleanskin impact structure, Northern Territory and Queensland, Australia: A reconnaissance study
Authors: Kenkmann* T. , Haines P.W. , Sweet† I.P. , Mitchell K. 
Published: June 2021

ABSTRACT
We report on the Cleanskin structure (18°10′00″S, 137°56′30″E), situated at the border between the Northern Territory and Queensland, Australia, and present results of preliminary geological fieldwork, microscopic analyses, and remote sensing. The Cleanskin structure is an eroded complex impact structure of ~15 km apparent diameter with a polygonal outline caused by two preexisting regional fault sets. The structure has a central uplift of ~6 km diameter surrounded by a rather shallow ring syncline. Based on stratigraphy, the uplift in the center may not exceed ~1000 m. The documentation of planar deformation features (PDFs), planar fractures (PFs), and feather features (FFs) in quartz grains from sandstone members of the Mesoproterozoic Constance Sandstone confirms the impact origin of the Cleanskin structure, as proposed earlier. The crater was most likely eroded before the Cambrian and later became buried beneath Cretaceous strata. We infer a late Mesoproterozoic to Neoproterozoic age of the impact event. In this chapter, the Cleanskin structure is compared with other midsized crater structures on Earth. Those with sandstone-dominated targets show structural similarities to the Cleanskin structure.
Sedimentation across the Paraburdoo spherule layer: Implications for the Neoarchean Earth system
Authors: Souders* Katrina S. , Davatzes* Alexandra K. , Ziegler* Brady A. , Goderis Steven , Déhais Thomas , Claeys Philippe 
Published: June 2021

ABSTRACT
Large bolide impacts in the Phanerozoic produced global change identifiable in the postimpact sediments. Aside from a few isolated examples, however, evidence of postimpact change associated with Precambrian impacts is sparse. This study used the Neoarchean Paraburdoo spherule layer as a case study to search for impact-induced change in the sediments above the spherule layer. We found possible minor sedimentary changes that may have been due to either a disturbance by bottom currents or changing diagenetic conditions. Contrary to the trends found with several post–Great Oxidation Event large bolide impacts, we found no evidence of shifts in tectonic regime, sediment weathering and deposition, or paleoenvironment induced by the Paraburdoo spherule layer impact, for which the impactor is estimated to have been approximately three times larger than the Cretaceous–Paleogene bolide. This lack of a clear signal of climatic shift may be due to one or more mechanisms. Either the Paraburdoo spherule layer’s deposition in several-hundred-meter-deep water within the Hamersley Basin of Western Australia was too deep to accumulate and record observable changes, or the Neoarchean’s high-CO2 atmospheric composition acted as a threshold below which the introduction of more impact-produced gases would not have produced the expected climatic and weathering changes. We also report minor traces of elevated iron and arsenic concentrations in the sediments immediately above the Paraburdoo spherule layer, consistent with trends observed above other distal impact deposits, as well as distinctive layers of hematite nodules bracketing the spherule layer. These geochemical changes may record ocean overturn of the Neoarchean stratified water column, which brought slightly oxygenated waters to depth, consistent with the observation of tsunami deposits in shallower impact deposits and/or heating of the global oceans by tens to hundreds of degrees Celsius in the wake of the Paraburdoo spherule layer impact. Either or both of these mechanisms in addition to impact-induced shallow-water ocean evaporation may also have caused a massive die-off of microbes, which also would have produced a postimpact increase in iron and arsenic concentrations.
Prospective oversight and approval of assisted dying cases in Victoria, Australia: a qualitative study of doctors’ perspectives
Authors: White Ben P , Willmott Lindy , Sellars Marcus , Yates Patsy 
Published: June 2021

BackgroundAssisted dying (AD) is increasingly becoming lawful internationally. While all AD models have oversight mechanisms, Victoria, Australia is rare in requiring formal approval before AD is permitted. Other jurisdictions are now enacting or implementing prospective approval models yet little is known about their operation. This paper reports the first empirical research internationally analysing the operation of a prospective approval model.MethodsThis qualitative study recruited doctors involved in providing lawful AD during the first year of the Victorian AD system. Recruitment occurred through the mandatory training doctors providing AD must undertake. Semistructured interviews were undertaken predominantly through Zoom conferencing, transcribed and thematically analysed.Results32 doctors from diverse specialties (including general practice) and diverse AD experiences were interviewed. Six themes were identified: (1) The primary gatekeeping to AD in practice was by the administrative Secretariat of the oversight body, the Voluntary Assisted Dying Review Board, and not the government department who issues the final ‘permit’; this may not have been intended by parliament. (2) The prospective oversight and approval process was bureaucratic and (3) the mandatory online system to manage AD was a barrier. (4) These factors caused unnecessary delays which (5) impeded AD for very sick patients. (6) However, this prospective process protected doctors and ensured system safety.ConclusionsPotential barriers to accessing AD posed by prospective approval should be evaluated carefully by jurisdictions implementing or considering such a model. Attention is needed not only to law but to system design and how AD is implemented in practice.
Artificial light improves size selection for northern shrimp (Pandalus borealis) in trawls
Authors: Ingólfsson Ólafur Arnar , Jørgensen Terje , Sistiaga Manu , Kvalvik Liz 
Published: June 2021

Size selection in the northern shrimp (Pandalus borealis) trawl fisheries is a widely studied topic. While the focus has largely been on codend and grid selectivity, studies have shown the importance of other design changes and the application of artificial light to evoke behavioural responses. LED lights of three different colours — green (∼470–580 nm), white (∼425–750 nm) and red (∼580–670 nm) — were mounted in the belly section of a shrimp trawl to investigate their influence on the overall selectivity of the trawl. The study was conducted using a twin-trawl setup, one with light and the other without light. For catch-comparison analysis, a polynomial regression with random effects was applied. The number of valid hauls with green, white and red lights were eleven, eight, and nine, respectively. All lights tested significantly affected the length-dependent retention of shrimp. Green light had the greatest effect, red the least. Significant loss was observed for shrimp below 17.5 mm carapace length (CL) for green light, 19.5 mm CL for white and 20.8 mm CL for red light.
The generation of matter–antimatter asymmetries and hypermagnetic fields by the chiral vortical effect of transient fluctuations
Authors: Abbaslu S. , Rostam Zadeh S. , Mehraeen M. , Gousheh S. S. 
Published: June 2021

AbstractWe study the contribution of the temperature-dependent chiral vortical effect to the generation and evolution of hypermagnetic fields and matter-antimatter asymmetries, in the symmetric phase of the early Universe, in the temperature range 100 GeV $$\le T \le $$

≤
T
≤

10 TeV. Our most important result is that, due to the chiral vortical effect, small overlapping transient fluctuations in the vorticity field in the plasma and temperature of matter degrees of freedom can lead to the generation of strong hypermagnetic fields and matter-antimatter asymmetries, all starting from zero initial values. We show that, either an increase in the amplitudes of the fluctuations of vorticity or temperature, or a decrease in their widths, leads to the production of stronger hypermagnetic fields, and therefore, larger matter-antimatter asymmetries. We have the interesting result that fluctuating vorticity fields are more productive, by many orders of magnitude, as compared to vorticities that are constant in time.
Adiabatic analysis of the rotating BTZ black hole
Authors: Fathi Mohsen , Lepe Samuel , Villanueva J. R. 
Published: June 2021

AbstractIn this paper we analyze some interesting features of the thermodynamics of the rotating BTZ black hole from the Carathéodory axiomatic postulate, for which, we exploit the appropriate Pfaffian form. The allowed adiabatic transformations are then obtained by solving the corresponding Cauchy problem, and are studied accordingly. Furthermore, we discuss the implications of our approach, regarding the second and third laws of black hole thermodynamics. In particular, the merging of two extremal black holes is studied in detail.
Preliminary evaluations of the environmental impact for the production of 99Mo by fusion neutrons
Authors: Contessa G. M. , D’Arienzo M. , Frisoni M. , Ferrari P. , Panichi R. , Moro F. , Pietropaolo A. 
Published: June 2021

AbstractENEA is developing an accelerator-driven 14 MeV neutron source exploiting the deuterium–tritium fusion reaction to produce 99Mo medical radioisotope as an alternative production route not based on fission reactors. It is expected that, during normal operation, a number of radionuclides, generated by means of neutron irradiation on the raw material (natural Molybdenum), will be produced and managed. The present manuscript, as foreseen by national law, discusses a hypothetical scenario to test the environmental screening models, in turn evaluating the mechanisms and parameters which affect and control the path of liquid effluents potentially released during normal operation of the facility. The aim is to estimate the amount of radioactivity to be operated and the fraction potentially discharged in this hypothetical scenario, so as to ensure that the radioactive material can be managed without any risk for the population and the environment, according to national regulations and thoroughly fulfilling the international guidelines.
Node-weighted Network Design in Planar and Minor-closed Families of Graphs
Authors: Chekuri Chandra , Ene Alina , Vakilian Ali 
Published: June 2021

We consider
node-weighted
survivable network design (SNDP) in planar graphs and minor-closed families of graphs. The input consists of a node-weighted undirected graph
G
= (
V
,
E
) and integer connectivity requirements
r
(
uv
) for each unordered pair of nodes
uv
. The goal is to find a minimum weighted subgraph
H
of
G
such that
H
contains
r
(
uv
) disjoint paths between
u
and
v
for each node pair
uv
. Three versions of the problem are edge-connectivity SNDP (EC-SNDP), element-connectivity SNDP (Elem-SNDP), and vertex-connectivity SNDP (VC-SNDP), depending on whether the paths are required to be edge, element, or vertex disjoint, respectively. Our main result is an
O
(
k
)-approximation algorithm for EC-SNDP and Elem-SNDP when the input graph is planar or more generally if it belongs to a proper minor-closed family of graphs; here,
k
= max

uv

r
(
uv
) is the maximum connectivity requirement. This improves upon the
O
(
k
log
n
)-approximation known for node-weighted EC-SNDP and Elem-SNDP in general graphs [31]. We also obtain an
O
(1) approximation for node-weighted VC-SNDP when the connectivity requirements are in {0, 1, 2}; for higher connectivity our result for Elem-SNDP can be used in a black-box fashion to obtain a logarithmic factor improvement over currently known general graph results. Our results are inspired by, and generalize, the work of Demaine, Hajiaghayi, and Klein [13], who obtained constant factor approximations for node-weighted Steiner tree and Steiner forest problems in planar graphs and proper minor-closed families of graphs via a primal-dual algorithm.
Navigating in Trees with Permanently Noisy Advice
Authors: Boczkowski Lucas , Feige Uriel , Korman Amos , Rodeh Yoav 
Published: June 2021

We consider a search problem on trees in which an agent starts at the root of a tree and aims to locate an adversarially placed treasure, by moving along the edges, while relying on local, partial information. Specifically, each node in the tree holds a pointer to one of its neighbors, termedadvice. A node is faulty with probabilityq. The advice at a non-faulty node points to the neighbor that is closer to the treasure, and the advice at a faulty node points to a uniformly random neighbor. Crucially, the advice ispermanent, in the sense that querying the same node again would yield the same answer. Let Δ denote the maximum degree. For the expected number of moves (edge traversals) until finding the treasure, we show that a phase transition occurs when thenoise parameterqis roughly 1 √Δ. Below the threshold, there exists an algorithm with expected number of movesO(D√Δ), whereDis the depth of the treasure, whereas above the threshold, every search algorithm has an expected number of moves, which is both exponential inDand polynomial in the number of nodes n. In contrast, if we require to find the treasure with probability at least 1 − δ, then for every fixed ɛ > 0, ifq< 1/Δɛ, then there exists a search strategy that with probability 1 − δ finds the treasure using (Δ−1D)O(1/ε)moves. Moreover, we show that (Δ−1D)Ω(1/ε)moves are necessary.
Graph Sparsification for Derandomizing Massively Parallel Computation with Low Space
Authors: Czumaj Artur , Davies Peter , Parter Merav 
Published: June 2021

The Massively Parallel Computation (MPC) model is an emerging model that distills core aspects of distributed and parallel computation, developed as a tool to solve combinatorial (typically graph) problems in systems of many machines with limited space.

Recent work has focused on the regime in which machines have sublinear (in
n
, the number of nodes in the input graph) space, with randomized algorithms presented for the fundamental problems of Maximal Matching and Maximal Independent Set. However, there have been no prior corresponding
deterministic
algorithms.

A major challenge underlying the sublinear space setting is that the local space of each machine might be too small to store all edges incident to a single node. This poses a considerable obstacle compared to classical models in which each node is assumed to know and have easy access to its incident edges. To overcome this barrier, we introduce a new
graph sparsification
technique that
deterministically
computes a low-degree subgraph, with the additional property that solving the problem on this subgraph provides significant progress towards solving the problem for the original input graph.

Using this framework to derandomize the well-known algorithm of Luby [SICOMP’86], we obtain
O
(log Δ + log log
n
)-round
deterministic
MPC algorithms for solving the problems of
Maximal Matching
and
Maximal Independent Set
with
O
(
n
ɛ
) space on each machine for any constant ɛ > 0. These algorithms also run in
O
(log Δ) rounds in the closely related model of CONGESTED CLIQUE, improving upon the state-of-the-art bound of
O
(log
2
Δ) rounds by Censor-Hillel et al. [DISC’17].
A Deeper Dive into Pattern-Aware Subgraph Exploration with PEREGRINE
Authors: Jamshidi Kasra , Vora Keval 
Published: June 2021

Graph mining workloads aim to extract structural properties of a graph by exploring its subgraph structures. PEREGRINE is a general-purpose graph mining system that provides a generic runtime to efficiently explore subgraph structures of interest and perform various graph mining analyses. It takes a 'pattern-aware' approach by incorporating a pattern-based programming model along with efficient pattern matching strategies. The programming model enables easier expression of complex graph mining use cases and enables PEREGRINE to extract the semantics of patterns. By analyzing the patterns, PEREGRINE generates efficient exploration plans which it uses to guide its subgraph exploration.
In this paper, we present an in-depth view of the patternanalysis techniques powering the matching engine of PEREGRINE. Beyond the theoretical foundations from prior research, we expose opportunities based on how the exploration plans are evaluated, and develop key techniques for computation reuse, enumeration depth reduction, and branch elimination. Our experiments show the importance of patternawareness for scalable and performant graph mining where the presented new techniques speed up the performance by up to two orders of magnitude on top of the benefits achieved from the prior theoretical foundations that generate the initial exploration plans.
GraphZero
Authors: Mawhirter Daniel , Reinehr Sam , Holmes Connor , Liu Tongping , Wu Bo 
Published: June 2021

Subgraph matching is a fundamental task in many applications which identifies all the embeddings of a query pattern in an input graph. Compilation-based subgraph matching systems generate specialized implementations for the provided patterns and often substantially outperform other systems. However, the generated code causes significant computation redundancy and the compilation process incurs too much overhead to be used online, both due to the inherent symmetry in the structure of the query pattern.
In this paper, we propose an optimizing query compiler, named GraphZero, to completely address these limitations through symmetry breaking based on group theory. GraphZero implements three novel techniques. First, its schedule explorer efficiently prunes the schedule space without missing any high-performance schedule. Second, it automatically generates and enforces a set of restrictions to eliminate computation redundancy. Third, it generalizes orientation, a surprisingly effective optimization that was only used for clique patterns, to apply to arbitrary patterns. Evaluation on multiple query patterns shows that GraphZero outperforms two state-of-the-art compilation and non-compilation based systems by up to 40X and 2654X, respectively.
GeoGraph
Authors: Wang Yiqiu , Yu Shangdi , Dhulipala Laxman , Gu Yan , Shun Julian 
Published: June 2021

In many applications of graph processing, the input data is often generated from an underlying geometric point data set. However, existing high-performance graph processing frameworks assume that the input data is given as a graph. Therefore, to use these frameworks, the user must write or use external programs based on computational geometry algorithms to convert their point data set to a graph, which requires more programming effort and can also lead to performance degradation.
In this paper, we present our ongoing work on the Geo- Graph framework for shared-memory multicore machines, which seamlessly supports routines for parallel geometric graph construction and parallel graph processing within the same environment. GeoGraph supports graph construction based on k-nearest neighbors, Delaunay triangulation, and b-skeleton graphs. It can then pass these generated graphs to over 25 graph algorithms. GeoGraph contains highperformance parallel primitives and algorithms implemented in C++, and includes a Python interface. We present four examples of using GeoGraph, and some experimental results showing good parallel speedups and improvements over the Higra library. We conclude with a vision of future directions for research in bridging graph and geometric data processing.
CuSP
Authors: Hoang Loc , Dathathri Roshan , Gill Gurbinder , Pingali Keshav 
Published: June 2021

Graph analytics systems must analyze graphs with billions of vertices and edges which require several terabytes of storage. Distributed-memory clusters are often used for analyzing such large graphs since the main memory of a single machine is usually restricted to a few hundreds of gigabytes. This requires partitioning the graph among the machines in the cluster. Existing graph analytics systems use a built-in partitioner that incorporates a particular partitioning policy, but the best policy is dependent on the algorithm, input graph, and platform. Therefore, built-in partitioners are not sufficiently flexible. Stand-alone graph partitioners are available, but they too implement only a few policies.
CuSP is a fast streaming edge partitioning framework which permits users to specify the desired partitioning policy at a high level of abstraction and quickly generates highquality graph partitions. For example, it can partition wdc12, the largest publicly available web-crawl graph with 4 billion vertices and 129 billion edges, in under 2 minutes for clusters with 128 machines. Our experiments show that it can produce quality partitions 6× faster on average than the state-of-theart stand-alone partitioner in the literature while supporting a wider range of partitioning policies.
Scalable Graph Neural Network Training
Authors: Serafini Marco , Guan Hui 
Published: June 2021

Graph Neural Networks (GNNs) are a new and increasingly popular family of deep neural network architectures to perform learning on graphs. Training them efficiently is challenging due to the irregular nature of graph data. The problem becomes even more challenging when scaling to large graphs that exceed the capacity of single devices. Standard approaches to distributed DNN training, like data and model parallelism, do not directly apply to GNNs. Instead, two different approaches have emerged in the literature: whole-graph and sample-based training.
In this paper, we review and compare the two approaches. Scalability is challenging with both approaches, but we make a case that research should focus on sample-based training since it is a more promising approach. Finally, we review recent systems supporting sample-based training.