Core and stellar mass functions in massive collapsing filaments

Context. The connection between the prestellar core mass function (CMF) and the stellar initial mass function (IMF) lies at the heart of all star formation theories, but it is inherently observationally unreachable. Aims. In this paper we aim to elucidate the earliest phases of star formation with a series of high-resolution numerical simulations that include the formation of sinks from high-density clumps. In particular, we focus on the transition from cores to sink particles within a massive molecular filament, and work towards identifying the factors that determine the shape of the CMF and the IMF. Methods. We have compared the CMF and IMF between magnetized and unmagnetized simulations, and between different resolutions. In order to study the effect of core stability, we applied different selection criteria according to the virial parameter and the mass-to-flux ratio of the cores. Results. We find that, in all models, selecting cores based on their kinematic virial parameter tends to exclude collapsing objects, because they host high velocity dispersions. Selecting only the thermally unstable magnetized cores, we observe that their mass-to-flux ratio spans almost two orders of magnitude for a given mass. We also see that, when magnetic fields are included, the CMF peaks at higher core mass values with respect to a pure hydrodynamical simulation. Nonetheless, all models produce sink mass functions with a high-mass slope consistent with Salpeter. Finally, we examined the effects of resolution and find that, in these isothermal simulations, even models with very high dynamical range fail to converge in the mass function. Conclusions. Our main conclusion is that, although the resulting CMFs and IMFs have similar slopes in all simulations, the cores have slightly different sizes and kinematical properties when a magnetic field is included, and this affects their gravitational stability. Nonetheless, a core selection based on the mass-to-flux ratio is not enough to alter the shape of the CMF, if we do not take thermal stability into account. Finally, we conclude that extreme care should be given to resolution issues when studying sink formation with an isothermal equation of state, since with each increase in resolution, fragmentation continues to smaller scales in a self-similar way.

Preparation and evaluation of 99mTc-labeled porphyrin complexes prepared using PNP and HYNIC cores: studying the effects of core selection on pharmacokinetics and tumor uptake in a mouse model

Demonstration of the effect of using two different 99mTc-cores for radiolabeling of the same ligand: differential in vivo outcome.

A Complexity Approach for Core-Selecting Exchange under Conditionally Lexicographic Preferences

Core-selection is a crucial property of rules in the literature of resource allocation. It is also desirable, from the perspective of mechanism design, to address the incentive of agents to cheat by misreporting their preferences. This paper investigates the exchange problem where (i) each agent is initially endowed with (possibly multiple) indivisible goods, (ii) agents' preferences are assumed to be conditionally lexicographic, and (iii) side payments are prohibited. We propose an exchange rule called augmented top-trading-cycles (ATTC), based on the original TTC procedure. We first show that ATTC is core-selecting and runs in polynomial time with respect to the number of goods. We then show that finding a beneficial misreport under ATTC is NP-hard. We finally clarify relationship of misreporting with splitting and hiding, two different types of manipulations, under ATTC.

Cross-domain variation in the X itself as a grammatical construction

The X itself is a nominal construction that has not received much attention within cognitive linguistics despite it having a quite interesting function, as it serves to select a core part in a partonomy and thus specify lexical relations within a text. Apart from being mentioned in passing in Croft & Cruse (2004), one of the few treatments of this construction in cognitive linguistics is Jensen (2014) who builds on the comments in Croft & Cruse (2004) and proposes a hypothesis pertaining to the cognitive and discursive function of the construction. However, that hypothesis does not take into account an important aspect of the reality of language — namely, variation. This article investigates, within the framework of usage-based construction grammar, the X itself in the Open American National Corpus (OANC) to see whether the construction displays variation across the nine domains that the data in OANC are divided into. Applying quantitative techniques, including lexical diversity measures and multidimensional scaling, this article explores aspects of the discursive behavior of the X itself across these domains and addresses the extent to which the construction interacts with the registers associated with the domains. Focusing on use-based varieties (McArthur 1992, see also Quirk 1989 and Halliday et al. 1964: 77), the present article argues that the X itself is not a constructional monolith, but that it is characterized by register-sensitive functional variation and that its core selection function very likely serves a information-structural discourse-pragmatic purpose.