Effects of husbandry parameters on the life-history traits of the apple snail, Marisa cornuarietis: effects of temperature, photoperiod, and population density

These experiments are part of a larger study designed to investigate the influence of husbandry parameters on the life history of the apple snail, Marisa cornuarietis. The overall objective of the program is to identify suitable husbandry conditions for maintaining multi-generation populations of this species in the laboratory for use in ecotoxicological testing. In this article, we focus on the effects of photoperiod, temperature, and population density on adult fecundity and juvenile growth. Increasing photoperiod from 12 to 16 h of light per day had no effect on adult fecundity or egg hatching and relatively minor effects on juvenile growth and development. Rearing snails at temperatures between 22°C and 28°C did not influence the rates of egg production or egg clutch size. However, the rates of growth and development (of eggs and juveniles) increased with increasing temperature in this range, and when temperatures were reduced to 22°C egg-hatching success was impaired. Juvenile growth and development were more sensitive to rearing density than adult fecundity traits. On the basis of the present results, we conclude that rearing individuals of M. cornuarietis at a temperature of 25°C, a photoperiod of 12L:12D, and a density of <0.8 snails L−1 (with lower densities for juvenile snails) should provide favorable husbandry conditions for maintaining multi-generation populations of this species

Hepatic artery thrombosis after pediatric liver transplantation a medical or surgical event

Hepatic artery thrombosis (HAT) is one of the most serious complications after orthotopic liver transplan¬tation, and is associated with a high morbidity and mor¬tality. This study retrospectively reviewed 66 liver transplants in children under the age of 10 years during1 a year-long period at a single institution.;A, total of 28 perioperative variables were analyzed to identify responsible factors of HAT. Of the 66 children, 18 (26%) developed HAT within 15 days after the transplant (HAT group); 29 (42%) had an uneventful postoperative course (control group). To avoid the possible influence of other complications 19 patients were excluded. Of the variables compared between the 2 study groups, three surgical factors (diameter of the hepatic artery-- greater or less than 3 mm; type of arterial anastomosis—end-to-end versus the use of an iliac graft or aortic conduit; and number of times the anastomosis was redone--one versus more than one), were found to be significantly different (P<.05) between HAT and control groups. Two medical factors also were significantly different: the use of intraoperative transfusion of fresh frozen plasma (FFP) and the administration of postoperative prophylactic anticoagulant treatment. A heparin and dextran-40 protocol appeared to be effective in preventing HAT (P<.02). Moreover, after multivariate analysis, anticoagulation therapy was demonstrated to with poor hepatic artery flow. © 1989 by The Williams and Wilkins Co

The Embedded View, its critics, and a radically non-representational solution

Whether perception involves the manipulation of representations is currently heavily debated. The Embedded View (EV) advanced by Nico Orlandi seeks a middle passage between representationalism and radical enactivism. In this paper I argue for a non-representational take on EV. I argue that this is the best way to resolve the objections EV has received from both representationalists and non-representationalists. I analyze this debate, and distinguish four sorts of objections: 1) the objection of the wrongfully cut middleman, 2) the argument against explanatory exclusionism, 3) the case for scientific benefits of representations, and 4) the charge of inconsistent ascription of representational status in EV. I argue that (1) the middleman was never cut in EV, and is controversial to boot, (2) otherwise equal, non-representational explanations have primacy over representational explanations, due to the lack of naturalistic grounds for representations and the unnecessarily ascribed cognitive load to the system. Further, I show that (3) puts the cart before the horse, and the arguments on offer are viciously circular. However, the final objection, (4) lays bare a deeper issue for EV. At the cost of giving up the middle position, however, the explanatory tools already available to EV can be shown to cover the work initially thought to require representation. I conclude that EV is best altered to be a non-representational theory of perception

Recycled Dark Matter

We outline a new production mechanism for dark matter that we dub "recycling": dark sector particles are kinematically trapped in the false vacuum during a dark phase transition; the false pockets collapse into primordial black holes (PBHs), which ultimately evaporate before Big Bang Nucleosynthesis (BBN) to reproduce the dark sector particles. The requirement that all PBHs evaporate prior to BBN necessitates high scale phase transitions and hence high scale masses for the dark sector particles in the true vacuum. Our mechanism is therefore particularly suited for the production of ultra heavy dark matter (UHDM) with masses above $\sim 10^{12}\,{\rm GeV}$. The correct relic density of UHDM is obtained because of the exponential suppression of the false pocket number density. Recycled UHDM has several novel features: the dark sector today consists of multiple decoupled species that were once in thermal equilibrium and the PBH formation stage has extended mass functions whose shape can be controlled by IR operators coupling the dark and visible sectors.Comment: 23 pages, 7 figures; v2: Lifetime of scalar updated. Conclusions unchange

The Primordial Black Holes that Disappeared: Connections to Dark Matter and MHz-GHz Gravitational Waves

In the post-LIGO era, there has been a lot of focus on primordial black holes (PBHs) heavier than $\sim 10^{15}$g as potential dark matter (DM) candidates. We point out that the branch of the PBH family that disappeared - PBHs lighter than $\sim 10^9$g that ostensibly Hawking evaporated away in the early Universe - also constitute an interesting frontier for DM physics. Hawking evaporation itself serves as a portal through which such PBHs can illuminate new physics, for example by emitting dark sector particles. Taking a simple DM scalar singlet model as a template, we compute the abundance and mass of PBHs that could have provided, by Hawking evaporation, the correct DM relic density. We consider two classes of such PBHs: those originating from curvature perturbations generated by inflation, and those originating from false vacuum collapse during a first-order phase transition. For PBHs of both origins we compute the gravitational wave (GW) signals emanating from their formation stage: from second-order effects in the case of curvature perturbations, and from sound waves in the case of phase transitions. The GW signals have peak frequencies in the MHz-GHz range typical of such light PBHs. We compute the strength of such GWs compatible with the observed DM relic density, and find that the GW signal morphology can in principle allow one to distinguish between the two PBH formation histories.Comment: 23 pages + references, 8 figure

Baryogenesis, Primordial Black Holes and MHz-GHz Gravitational Waves

Gravitational waves (GWs) in the MHz - GHz frequency range are motivated by a host of early Universe phenomena such as oscillons, preheating, and cosmic strings. We point out that baryogenesis too serves as a motivation to probe GWs in this frequency range. The connection is through primordial black holes (PBHs): on the one hand, PBHs induce baryogenesis by Hawking evaporating into a species that has baryon number and $CP$ violating decays; on the other, PBHs induce GWs through second order effects when the scalar fluctuations responsible for their formation re-enter the horizon. We describe the interplay of the parameters responsible for successful baryogenesis on the plane of the strain and frequency of the induced GWs, being careful to delineate regimes where PBH domination or washout effects occur. We provide semi-analytic scalings of the GW strain with the baryon number to entropy ratio and other parameters important for baryogenesis. Along the way, we sketch a solution to the dark matter-baryogenesis coincidence problem with two populations of PBHs, which leads to a double-peaked GW signal. Our results underscore the importance of probing the ultra high frequency GW frontier.Comment: 35 pages, 9 figures. v2: added references, corrected a typo in Eq. (3.12), version published in JCA

Satisfiability of ECTL* with tree constraints

Recently, we have shown that satisfiability for $\mathsf{ECTL}^*$ with constraints over $\mathbb{Z}$ is decidable using a new technique. This approach reduces the satisfiability problem of $\mathsf{ECTL}^*$ with constraints over some structure A (or class of structures) to the problem whether A has a certain model theoretic property that we called EHD (for "existence of homomorphisms is decidable"). Here we apply this approach to concrete domains that are tree-like and obtain several results. We show that satisfiability of $\mathsf{ECTL}^*$ with constraints is decidable over (i) semi-linear orders (i.e., tree-like structures where branches form arbitrary linear orders), (ii) ordinal trees (semi-linear orders where the branches form ordinals), and (iii) infinitely branching trees of height h for each fixed $h\in \mathbb{N}$. We prove that all these classes of structures have the property EHD. In contrast, we introduce Ehrenfeucht-Fraisse-games for $\mathsf{WMSO}+\mathsf{B}$ (weak $\mathsf{MSO}$ with the bounding quantifier) and use them to show that the infinite (order) tree does not have property EHD. As a consequence, a different approach has to be taken in order to settle the question whether satisfiability of $\mathsf{ECTL}^*$ (or even $\mathsf{LTL}$) with constraints over the infinite (order) tree is decidable

Enactive-Dynamic Social Cognition and Active Inference

The aim of this paper is twofold: it critically analyses and rejects accounts blending active inference as theory of mind and enactivism; and it advances an enactivist-dynamic account of social cognition that is compatible with active inference. While some inference models of social cognition seemingly take an enactive perspective on social cognition, they explain it as the attribution of mental states to other people, via representational machinery, in line with Theory of Mind (ToM). Holding both enactivism and ToM, we argue, entails contradiction and confusion due to two ToM assumptions rejected by enactivism: (1) that social cognition reduces to mental representation and (2) cognition must be hardwired with a social cognition contentful “toolkit” or “starter pack” for fueling the model-like theorising supposed in (1). The paper offers a positive alternative, one that avoids contradictions or confusions. After clarifying the profile of social cognition under enactivism, i.e. without assumptions (1) and (2), the last section advances an enactivist-dynamic model of cognition as dynamic, real time, fluid, dynamic, contextual social action, where we use the formalisms of dynamical systems theory to explain the origins of sociocognitive novelty in developmental change and active inference as a tool to explain social understanding as generalised synchronisation

Enactive-Dynamic Social Cognition and Active Inference

The aim of this paper is twofold: it critically analyses and rejects accounts blending active inference as theory of mind and enactivism; and it advances an enactivist-dynamic account of social cognition that is compatible with active inference. While some inference models of social cognition seemingly take an enactive perspective on social cognition, they explain it as the attribution of mental states to other people, via representational machinery, in line with Theory of Mind (ToM). Holding both enactivism and ToM, we argue, entails contradiction and confusion due to two ToM assumptions rejected by enactivism: (1) that social cognition reduces to mental representation and (2) cognition must be hardwired with a social cognition contentful “toolkit” or “starter pack” for fueling the model-like theorising supposed in (1). The paper offers a positive alternative, one that avoids contradictions or confusions. After clarifying the profile of social cognition under enactivism, i.e. without assumptions (1) and (2), the last section advances an enactivist-dynamic model of cognition as dynamic, real time, fluid, dynamic, contextual social action, where we use the formalisms of dynamical systems theory to explain the origins of sociocognitive novelty in developmental change and active inference as a tool to explain social understanding as generalised synchronisation