2,518 research outputs found
Case stacking below the surface: On the possessor case alternation in Udmurt
In this paper we investigate the case split on the possessor in Udmurt. Traditionally, the choice between ablative and genitive possessor case is said to be driven by the grammatical function (GF) of the XP containing the possessor. We argue that the case split is not driven by GFs; rather, it is determined by the case value of the XP that contains the possessor. Importantly, there is no evidence
which points to a possessor raising analysis in Udmurt. Instead, we present an analysis according to which the possessor always bears genitive but may be assigned another structural case by an external head. Due to a morphological constraint, stacked case features fuse into a single feature set in the postsyntactic morphological component. If accusative and genitive stack on the possessor, only the default semantic case marker, i.e., the ablative marker, can realize the resulting feature set. In any other context the genitive marker is chosen.
We thus claim that there is no abstract ablative on the possessor; instead, the morphological ablative marker realizes a combination of two abstract structural cases
Neutron-proton scattering at next-to-next-to-leading order in Nuclear Lattice Effective Field Theory
We present a systematic study of neutron-proton scattering in Nuclear Lattice
Effective Field Theory (NLEFT), in terms of the computationally efficient
radial Hamiltonian method. Our leading-order (LO) interaction consists of
smeared, local contact terms and static one-pion exchange. We show results for
a fully non-perturbative analysis up to next-to-next-to-leading order (NNLO),
followed by a perturbative treatment of contributions beyond LO. The latter
analysis anticipates practical Monte Carlo simulations of heavier nuclei. We
explore how our results depend on the lattice spacing a, and estimate sources
of uncertainty in the determination of the low-energy constants of the
next-to-leading-order (NLO) two-nucleon force. We give results for lattice
spacings ranging from a = 1.97 fm down to a = 0.98 fm, and discuss the effects
of lattice artifacts on the scattering observables. At a = 0.98 fm, lattice
artifacts appear small, and our NNLO results agree well with the Nijmegen
partial-wave analysis for S-wave and P-wave channels. We expect the peripheral
partial waves to be equally well described once the lattice momenta in the
pion-nucleon coupling are taken to coincide with the continuum dispersion
relation, and higher-order (N3LO) contributions are included. We stress that
for center-of-mass momenta below 100 MeV, the physics of the two-nucleon system
is independent of the lattice spacing.Comment: 22 pages, 8 figure
Maximum Sum Rate of Non-regenerative Two-way Relaying in Systems with Different Complexities
Abstract-This paper considers the two-hop relaying case with bi-directional communication of two multiple-antenna nodes S1 and S2 via an intermediate multiple-antenna node, namely the relay station (RS). A general framework for the sum rate maximization in linear, non-regenerative two-way relaying with multiple-antenna nodes is proposed assuming all nodes have perfect channel state information (CSI) in order to perform linear beamforming (BF). There may be application cases in which the system cannot provide perfect CSI to all nodes or the nodes cannot be such complex. Hence, three different cases of system complexity are investigated which are shown to be special cases of the introduced framework. Firstly, all nodes can perform BF, secondly only S1 and S2 can perform BF, and thirdly only the RS can perform BF. The optimum performances of all three cases are compared to each other by means of numeric optimizations, and approaches to solve the resulting optimization problems are proposed. It is shown that applying BF exclusively at the RS provides the same performance as applying BF at all nodes
A Threat Model for Vehicular Fog Computing
Vehicular Fog Computing (VFC) facilitates the deployment of distributed, latency-aware services, residing between smart vehicles and cloud services. However, VFC systems are exposed to manifold security threats, putting human life at risk. Knowledge on such threats is scattered and lacks empirical validation. We performed an extensive threat assessment by reviewing literature and conducting expert interviews, leading to a comprehensive threat model with 33 attacks and example security mitigation strategies, among others. We thereby synthesize and extend prior research; provide rich descriptions for threats; and raise awareness of physical attacks that underline importance of the cyber-physical manifestation of VFC
Nuclear binding near a quantum phase transition
How do protons and neutrons bind to form nuclei? This is the central question
of ab initio nuclear structure theory. While the answer may seem as simple as
the fact that nuclear forces are attractive, the full story is more complex and
interesting. In this work we present numerical evidence from ab initio lattice
simulations showing that nature is near a quantum phase transition, a
zero-temperature transition driven by quantum fluctuations. Using lattice
effective field theory, we perform Monte Carlo simulations for systems with up
to twenty nucleons. For even and equal numbers of protons and neutrons, we
discover a first-order transition at zero temperature from a Bose-condensed gas
of alpha particles (4He nuclei) to a nuclear liquid. Whether one has an
alpha-particle gas or nuclear liquid is determined by the strength of the
alpha-alpha interactions, and we show that the alpha-alpha interactions depend
on the strength and locality of the nucleon-nucleon interactions. This insight
should be useful in improving calculations of nuclear structure and important
astrophysical reactions involving alpha capture on nuclei. Our findings also
provide a tool to probe the structure of alpha cluster states such as the Hoyle
state responsible for the production of carbon in red giant stars and point to
a connection between nuclear states and the universal physics of bosons at
large scattering length.Comment: Published version to appear in Physical Review Letters. Main: 5
pages, 3 figures. Supplemental material: 13 pages, 6 figure
Impact investments: a call for (re)orientation
Practitioners and academics have been using different terms to describe investments in the sustainability context. The latest inflationary term is impact investments—investments that focus on real-world changes in terms of solving social challenges and/or mitigating ecological degradation. At the core of this definition is an emphasis on transformational changes. However, the term impact investment is often used interchangeably for any investment that incorporates environmental, social, and governance (ESG) aspects. In the latter instance, achieving transformational change is not the main purpose of such investments, which therefore carries the risk of impact washing (akin to “green washing”). To offer (re-)orientation from an academic perspective, we derive a new typology of sustainable investments. This typology delivers a precise definition of what impact investments are and what they should cover. As one central contribution, we propose distinguishing between impact-aligned investments and impact-generating investments. Based on these insights, we hope to lay the foundation for future research and debates in the field of impact investing by practitioners, policymakers, and academics alike
Subarctic catchment water storage and carbon cycling – Leading the way for future studies using integrated datasets at Pallas, Finland
Subarctic ecohydrological processes are changing rapidly, but detailed and integrated ecohydrological investigations are not as widespread as necessary. We introduce an integrated research catchment site (Pallas) for atmosphere, ecosystems, and ecohydrology studies in subarctic conditions in Finland that can be used for a new set of comparative catchment investigations. The Pallas site provides unique observational data and high-intensity field measurement datasets over long periods. The infrastructure for atmosphere- to landscape-scale research in ecosystem processes in a subarctic landscape has recently been complemented with detailed ecohydrological measurements. We identify three dominant processes in subarctic ecohydrology: (a) strong seasonality drives ecohydrological regimes, (b) limited dynamic storage causes rapid stream response to water inputs (snowmelt and intensive storms), and (c) hydrological state of the system regulates catchment-scale dissolved carbon dynamics and greenhouse (GHG) fluxes. Surface water and groundwater interactions play an important role in regulating catchment-scale carbon balances and ecosystem respiration within subarctic peatlands, particularly their spatial variability in the landscape. Based on our observations from Pallas, we highlight key research gaps in subarctic ecohydrology and propose several ways forward. We also demonstrate that the Pallas catchment meets the need for sustaining and pushing the boundaries of critical long-term integrated ecohydrological research in high-latitude environments.Peer reviewe
Ab initio alpha-alpha scattering
Processes involving alpha particles and alpha-like nuclei comprise a major
part of stellar nucleosynthesis and hypothesized mechanisms for thermonuclear
supernovae. In an effort towards understanding alpha processes from first
principles, we describe in this letter the first ab initio calculation of
alpha-alpha scattering. We use lattice effective field theory to describe the
low-energy interactions of nucleons and apply a technique called the adiabatic
projection method to reduce the eight-body system to an effective two-cluster
system. We find good agreement between lattice results and experimental phase
shifts for S-wave and D-wave scattering. The computational scaling with
particle number suggests that alpha processes involving heavier nuclei are also
within reach in the near future.Comment: 6 pages, 6 figure
Study Protocol PROMETHEUS:Prospective Multicenter Study to Evaluate the Correlation Between Safety Margin and Local Recurrence After Thermal Ablation Using Image Co-registration in Patients with Hepatocellular Carcinoma
Purpose: The primary objective is to determine the minimal ablation margin required to achieve a local recurrence rate of 18 years with Barcelona Clinic Liver Cancer stage 0/A hepatocellular carcinoma (or B with a maximum of two lesions < 5 cm each) are eligible. Patients will undergo dual-phase contrast-enhanced computed tomography directly before and after ablation. Ablation margins will be quantitatively assessed using co-registration software, blinding assessors (i.e. two experienced radiologists) for outcome. Presence and location of recurrence are evaluated independently on follow-up scans by two other experienced radiologists, blinded for the quantitative margin analysis. A sample size of 189 tumors (~ 145 patients) is required to show with 80% power that the risk of local recurrence is confidently below 10%. A two-sided binomial z-test will be used to test the null hypothesis that the local recurrence rate is ≥ 10% for patients with a minimal ablation margin ≥ 2 mm. Logistic regression will be used to find the relationship between minimal ablation margins and local recurrence. Kaplan–Meier estimates are used to assess local and overall recurrence, disease-free and overall survival. Discussion: It is expected that this study will result in a clear understanding of the correlation between ablation margins and local recurrence. Using co-registration software in future patients undergoing ablation for hepatocellular carcinoma may improve intraprocedural evaluation of technical success. Trial registration The Netherlands Trial Register (NL9713), https://www.trialregister.nl/trial/9713
- …