213 research outputs found
The Not-So Dramatic Effect of Advective Flows on Gas Accretion
Super-Earths and mini-Neptunes are the most common types of exoplanets
discovered, yet the physical scenarios behind their formation are still
debated. Standard core accretion models in gas-rich environment find that
typical mini-Neptune mass planets would blow up into Jupiters before the
underlying disk gas dissipates away. The injection of entropy from the
protoplanetary disk into forming gaseous envelopes has recently been put
forward as a mechanism to delay this runaway accretion, specifically at short
orbital distances. Here, we reevaluate this line of reasoning by incorporating
recycling flows of gas into a numerical one-dimensional thermodynamic model
with more realistic equation of state and opacities and the thermal state of
the advective flow. At 0.1 AU, unless these advective flows can penetrate below
0.2 of the planet's gravitational sphere of influence, the gas-to-core
mass ratio (GCR) stays above 10% before the nebular disk dissipates which
is still too large to explain the measured properties of mini-Neptunes,
necessitating other gas-limiting processes such as late-time core assembly. The
effect of entropy advection on gas accretion weakens even further at wider
orbital separations. We present an updated scaling relation between GCR and the
penetration depth of the advective flows which varies non-trivially with
orbital distances, core masses and dusty vs.~dust-free opacity. We further
demonstrate how measurements of planet mass distribution beyond 1 AU can
be used to disambiguate between different formation conditions of gas-poor
planets.Comment: 16 pages, 9 figures. Submitted to ApJ. Comments welcome
Transitions/relaxations in polyester adhesive/PET system
The correlations between the transitions and the dielectric relaxation processes of the oriented poly(ethylene terephthalate) (PET) pre-impregnated of the polyester thermoplastic adhesive have been investigated by differential scanning calorimetry (DSC) and dynamic dielectric spectroscopy (DDS). The thermoplastic polyester adhesive and the oriented PET films have been studied as reference samples. This study evidences that the adhesive chain segments is responsible for the physical structure evolution in the PET-oriented film. The transitions and dielectric relaxation modes’ evolutions in the glass transition region appear characteristic of the interphase between adhesive and PET film, which is discussed in terms of molecular mobility. The storage at room temperature of the adhesive tape involves the heterogeneity of the physical structure, characterized by glass transition dissociation. Thus, the correlation between the transitions and the dielectric relaxation processes evidences a segregation of the amorphous phases. Therefore, the physical structure and the properties of the material have been linked to the chemical characteristics
Androgen signaling negatively controls group 2 innate lymphoid cells
Prevalence of asthma is higher in women than in men, but the mechanisms underlying this sex bias are unknown. Group 2 innate lymphoid cells (ILC2s) are key regulators of type 2 inflammatory responses. Here, we show that ILC2 development is greatly influenced by male sex hormones. Male mice have reduced numbers of ILC2 progenitors (ILC2Ps) and mature ILC2s in peripheral tissues compared with females. In consequence, males exhibit reduced susceptibility to allergic airway inflammation in response to environmental allergens and less severe IL-33-driven lung inflammation, correlating with an impaired expansion of lung ILC2s. Importantly, orchiectomy, but not ovariectomy, abolishes the sex differences in ILC2 development and restores IL-33-mediated lung inflammation. ILC2Ps express the androgen receptor (AR), and AR signaling inhibits their differentiation into mature ILC2s. Finally, we show that hematopoietic AR expression limits IL-33-driven lung inflammation through a cell-intrinsic inhibition of ILC2 expansion. Thus, androgens play a crucial protective role in type 2 airway inflammation by negatively regulating ILC2 homeostasis, thereby limiting their capacity to expand locally in response to IL-33.PMC546100
Complementarities between Barriers to Innovation: Data Evidence from Poland
This paper investigates the barriers to innovation perceived by Polish manufacturing firms. It refers to the heterogeneity of innovation active firms. We introduce a taxonomy of innovative firms based on the frequency with which they introduce commercialised innovations using data from both CIS4 (for 2002-2004) and CIS5 (2004-2006). Two groups of innovation-active firms are distinguished: those which introduced innovation in both periods covered by both CIS (which we call persistent innovators) and those which introduced innovation either in CIS4 or CIS5 (which we call occasional innovators). We use a four step analysis covering binary correlations, Principal Component Analysis, probit model and correlations of disturbances. Two types of explanatory variables describing firms' characteristics and innovation inputs used are considered. The paper shows that there are considerable differences in sensitivities to the perception of innovation barriers and in complementarities among barriers between persistent and occasional innovators. In the case of occasional innovators, a kind of innovation barrier chain is observed. This has an impact on differences in the frequency of innovation activities between the two groups of innovators and results in a diversification of innovators
Pain shared, pain halved? Cooperation as a coping strategy for innovation barriers
The paper analyses the relationship between the perception of barriers to innovation and the firm’s propensity to cooperate to mitigate their effect. First, we look at whether cooperation with research organizations or private firms is associated with experiencing different types of barriers, for example, financial constraints, lack of human capital or uncertain market demand. Second, we test whether experiencing several types of barriers simultaneously has a super-modular effect on the propensity to cooperate tout court, and the choice of cooperation partner. We find that having to face a single, specific constraint leads to firms ‘sharing the pain’ with cooperation partners—both research organization and other firms. However, the results of a super-modularity test show that having to cope with different barriers is a deterrent to establishing cooperation agreements, especially when firms lack finance, adequate skills and information on technology or markets. The paper adds to the innovation literature by identifying the factors associated with firms’ coping with different barriers by applying a selective cooperation strategy
Long-Lasting Consequences of Neonatal Maternal Separation on Social Behaviors in Ovariectomized Female Mice
Maternal separation (MS) stress is known to induce long-lasting alterations in emotional and anxiety-related behaviors, but effects on social behaviors are not well defined. The present study examined MS effects on female social behaviors in the social investigation (SIT) and social preference (SPT) tests, in addition to non-social behaviors in the open-field (OFT) and light-dark transition (LDT) tests in C57BL/6J mice. All females were tested as ovariectomized to eliminate confounding effects of endogenous estrogen during behavioral testing. Daily MS (3 hr) from postnatal day 1 to 14 did not affect anxiety levels in LDT, but were elevated in OFT with modified behavioral responses to the novel environment. Furthermore, MS altered social investigative behaviors and preference patterns toward unfamiliar stimulus mice in SIT and short- and long-term SPT paradigms. In SIT, MS reduced social investigation duration and increased number of stretched approaches towards both female and male unfamiliar stimulus mice, suggesting increased social anxiety levels in MS females. Similarly, MS heightened levels of social anxiety during short-term SPT but no MS effect on social preference was found. On the other hand, MS females displayed a distinctive preference for female stimuli, unlike control females, when tested for long-term SPT over a prolonged period of 5 days. Evaluation of FosB expression in the paraventricular nucleus, medial and central amygdala following stimulus exposure demonstrated greater number of FosB immunopositive cells in all three brain regions in MS females compared to control females. These results suggest that MS females might differ in neuroendocrine responses toward unfamiliar female and male opponents, which may be associated with modifications in social behaviors found in the present study. Taken together, this study provides new evidence that early life stress modifies female social behaviors by highlighting alterations in behavioral responses to situations involving social as well as non-social novelty
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