Effects of Extreme Obliquity Variations on the Habitability of Exoplanets

We explore the impact of obliquity variations on planetary habitability in hypothetical systems with high mutual inclination. We show that large amplitude, high frequency obliquity oscillations on Earth-like exoplanets can suppress the ice-albedo feedback, increasing the outer edge of the habitable zone. We restrict our exploration to hypothetical systems consisting of a solar-mass star, an Earth-mass planet at 1 AU, and 1 or 2 larger planets. We verify that these systems are stable for $10^8$ years with N-body simulations, and calculate the obliquity variations induced by the orbital evolution of the Earth-mass planet and a torque from the host star. We run a simplified energy balance model on the terrestrial planet to assess surface temperature and ice coverage on the planet's surface, and we calculate differences in the outer edge of the habitable zone for planets with rapid obliquity variations. For each hypothetical system, we calculate the outer edge of habitability for two conditions: 1) the full evolution of the planetary spin and orbit, and 2) the eccentricity and obliquity fixed at their average values. We recover previous results that higher values of fixed obliquity and eccentricity expand the habitable zone, but also find that obliquity oscillations further expand habitable orbits in all cases. Terrestrial planets near the outer edge of the habitable zone may be more likely to support life in systems that induce rapid obliquity oscillations as opposed to fixed-spin planets. Such planets may be the easiest to directly characterize with space-borne telescopes.Comment: 46 pages, 12 Figures, 5 Table

An Injectable Trace Mineral Supplement in Yearling Bulls Causes a Short-Term Increase in Circulating Trace Mineral Levels But Does Not Improve Sperm Quality

Proper trace mineral supplementation is necessary for reproductive development and function. Supplementation with various trace minerals has been shown to improve overall sperm quality and morphology and increase the percentage of live sperm. When developing beef bulls, it is necessary to meet trace mineral requirements to ensure proper reproductive success. An injectable trace mineral product has been made commercially available for use in cattle as a supplemental form of chelated selenium, copper, zinc, and manganese. Considering the role of trace minerals in bull reproductive function, we posed the question of whether using an injectable trace mineral product beyond dietary supplementation could improve sperm quality and percentage of bulls passing yearling breeding soundness exams. The objectives of our study were to compare serum trace mineral concentrations of bulls before and after administration of an injection of trace minerals or saline and to compare semen trace mineral concentrations after treatment. To determine if an injectable trace mineral product could be of benefit, we compared serum and semen trace mineral concentrations as well as semen quality and percentage passing a yearling breeding soundness examination in treated and untreated bulls

Presynchronizing PGF2α and GnRH injections before timed artificial insemination CO-Synch + CIDR program

Fixed-time artificial insemination is an effective management tool that reduces the labor associated with more conventional artificial insemination programs requiring detection of estrus. The 7-day CO-Synch + controlled internal drug release (CIDR) insert protocol has been shown to effectively initiate estrus and ovulation in cycling and non-cycling suckled beef cows, producing pregnancy rates at or greater than 50% in beef cows. The gonadotropin-releasing hormone (GnRH) injection that begins the CO-Synch + CIDR program initiates ovulation in a large proportion of cows, particularly anestrous cows. The CIDR, which releases progesterone intravaginally, prevents short estrous cycles that usually follow the first postpartum ovulation in beef cows. Our hypothesis was that inducing estrus with a prostaglandin injection followed 3 days later with a GnRH injection, 7 days before applying the 7-day CO-Synch + CIDR protocol, might increase the percentage of cycling cows that would exhibit synchronous follicular waves after the onset of the CO-Synch + CIDR protocol. We also hypothesized that the additional GnRH injection would increase the percentage of anestrous cows that would ovulate, thereby increasing pregnancy outcomes

Journalism expands in spite of the crisis: digital-native news media in Spain

Digital-native news organizations have grown steadily in Spain since the mid-1990s and they have become established as a major force in the media market. Paradoxically, their biggest expansion coincided with the Great Recession (2008–2014). In fact, their numbers increased most during 2012–2013, when traditional media were cutting staff in response to the economic crisis, and unemployment rates in the media sector as a whole hit their peak. However, these digital-native news startups have yet to prove their sustainability and stability. This study uses our own database of 3,862 native and non-native digital news outlets in Spain and the Reuters Institute Digital News Report to analyze a number of characteristics of these media, such as the percentage that have gone inactive, the relative popularity of legacy brands vs. digital natives, multi-platform synergies, content subject matter, geographical location, ownership, and funding sources. Based on these quantitative parameters, this study reviews the structural strengths and weaknesses of digital-native media in the Spanish news market. Taking into account these findings, we conclude that the surge in digital-native news media observed in Spain during the Great Recession followed the pattern of creative destruction described by several economists

El ecosistema que viene

En 2011, Iñaki Gabilondo publicaba un libro de título cre- puscular: El fin de una época. Uno de los periodistas más presti- giosos de España entonaba en aquellas páginas una despedida si no a la profesión —en 2018 continúa analizando la actualidad en un videoblog de El País—, sí al menos a cierta forma de ejercerla. «El periodismo —escribía— está viviendo una verda- dera transición de una época a otra, la muerte de un ciclo y el nacimiento de otro. Estamos en pleno proceso de despedida del mundo que habíamos conocido para dirigirnos, aún de manera imprecisa, hacia ese nuevo universo complejísimo de lo digital y las nuevas conectividades» (Gabilondo, 2011: 149-150). En efecto, para cuando se escribían esas líneas, las tecnologías di- gitales no solo habían modificado las herramientas con las que nos informamos, sino que, apenas en un cuarto de siglo, habían transformado el periodismo en su integridad. Con ello, se han abierto tantas incógnitas como oportunidades. Al compás de los cambios tecnológicos, han evolucionado los lenguajes informativos, los procesos de trabajo en las redaccio- nes, los perfiles profesionales de los periodistas, las formas en las que estos se relacionan con la audiencia y, en definitiva, todos y cada uno de los ámbitos en los que se concreta la actividad periodística. Como resultado de esos cambios, tal y como reve- lan los capítulos anteriores, en España ha emergido un nuevo mercado periodístico

Self-Assembly of Supramolecular Triblock Copolymer Complexes

Four different poly(tert-butoxystyrene)-b-polystyrene-b-poly(4-vinylpyridine) (PtBOS-b-PS-b-P4VP) linear triblock copolymers, with the P4VP weight fraction varying from 0.08 to 0.39, were synthesized via sequential anionic polymerization. The values of the unknown interaction parameters between styrene and tert-butoxystyrene and between tert-butoxystyrene and 4-vinylpyridine were determined from random copolymer blend miscibility studies and found to satisfy 0.031<χS,tBOS<0.034 and 0.39<χ4VP,tBOS<0.43, the latter being slightly larger than the known 0.30<χS,4VP≤0.35 value range. All triblock copolymers synthesized adopted a P4VP/PS core/shell cylindrical self-assembled morphology. From these four triblock copolymers supramolecular complexes were prepared by hydrogen bonding a stoichiometric amount of pentadecylphenol (PDP) to the P4VP blocks. Three of these complexes formed a triple lamellar ordered state with additional short length scale ordering inside the P4VP(PDP) layers. The self-assembled state of the supramolecular complex based on the triblock copolymer with the largest fraction of P4VP consisted of alternating layers of PtBOS and P4VP(PDP) layers with PS cylinders inside the latter layers. The difference in morphology between the triblock copolymers and the supramolecular complexes is due to two effects: (i) a change in effective composition and, (ii) a reduction in interfacial tension between the PS and P4VP containing domains. The small angle X-ray scattering patterns of the supramolecules systems are very temperature sensitive. A striking feature is the disappearance of the first order scattering peak of the triple lamellar state in certain temperature intervals, while the higher order peaks (including the third order) remain. This is argued to be due to the thermal sensitivity of the hydrogen bonding and thus directly related to the very nature of these systems.

Pattern formation in 2-frequency forced parametric waves

We present an experimental investigation of superlattice patterns generated on the surface of a fluid via parametric forcing with 2 commensurate frequencies. The spatio-temporal behavior of 4 qualitatively different types of superlattice patterns is described in detail. These states are generated via a number of different 3--wave resonant interactions. They occur either as symmetry--breaking bifurcations of hexagonal patterns composed of a single unstable mode or via nonlinear interactions between the two primary unstable modes generated by the two forcing frequencies. A coherent picture of these states together with the phase space in which they appear is presented. In addition, we describe a number of new superlattice states generated by 4--wave interactions that arise when symmetry constraints rule out 3--wave resonances.Comment: The paper contains 34 pages and 53 figures and provides an extensive review of both the theoretical and experimental work peformed in this syste

Weak Segregation Theory and Non-Conventional Morphologies in the Ternary ABC Triblock Copolymers

The Leibler weak segregation theory in molten diblock copolymers is generalized with due regard for the 2nd shell harmonics contributions defined in the paper and the phase diagrams are built for the linear and miktoarm ternary ABC triblock copolymers. The symmetric linear copolymers with the middle block non-selective with respect to the side ones are shown to undergo the continuous ODT not only into the lamellar phase but also into various non-conventional cubic phases (depending on the middle block composition it could be the simple cubic, face-centered cubic or non-centrosymmetric phase revealing the symmetry of space group No.214 first predicted to appear in molten block copolymers). For asymmetric linear ABC copolymers a region of compositions is found where the weakly segregated gyroid (double gyroid) phase exists between the planar hexagonal and lamellar or one of the non-conventional cubic phases up to the very critical point. In contrast, the miktoarm ABC block copolymers with one of its arm non-selective with respect to the two others are shown to reveal a pronounced tendency towards strong segregation, which is preceded by increase of stability of the conventional BCC phase and a peculiar weakly segregated BCC phase (BCC3), where the dominant harmonics belong to the 3rd co-ordination sphere of the reciprocal lattice. The validity region of the developed theory is discussed and outlined in the composition triangles both for linear and miktoarm copolymers.Comment: 61 pages, 12 figure

Predicting richness and composition in mountain insect communities at high resolution: a new test of the SESAM framework

Aim The aim of this study was to test different modelling approaches, including a new framework, for predicting the spatial distribution of richness and composition of two insect groups. Location The western Swiss Alps. Methods We compared two community modelling approaches: the classical method of stacking binary prediction obtained fromindividual species distribution models (binary stacked species distribution models, bS-SDMs), and various implementations of a recent framework (spatially explicit species assemblage modelling, SESAM) based on four steps that integrate the different drivers of the assembly process in a unique modelling procedure. We used: (1) five methods to create bS-SDM predictions; (2) two approaches for predicting species richness, by summing individual SDM probabilities or by modelling the number of species (i.e. richness) directly; and (3) five different biotic rules based either on ranking probabilities from SDMs or on community co-occurrence patterns. Combining these various options resulted in 47 implementations for each taxon. Results Species richness of the two taxonomic groups was predicted with good accuracy overall, and in most cases bS-SDM did not produce a biased prediction exceeding the actual number of species in each unit. In the prediction of community composition bS-SDM often also yielded the best evaluation score. In the case of poor performance of bS-SDM (i.e. when bS-SDM overestimated the prediction of richness) the SESAM framework improved predictions of species composition. Main conclusions Our results differed from previous findings using community-level models. First, we show that overprediction of richness by bS-SDM is not a general rule, thus highlighting the relevance of producing good individual SDMs to capture the ecological filters that are important for the assembly process. Second, we confirm the potential of SESAM when richness is overpredicted by bS-SDM; limiting the number of species for each unit and applying biotic rules (here using the ranking of SDM probabilities) can improve predictions of species compositio

Rats use memory confidence to guide decisions.

Memory enables access to past experiences to guide future behavior. Humans can determine which memories to trust (high confidence) and which to doubt (low confidence). How memory retrieval, memory confidence, and memory-guided decisions are related, however, is not understood. In particular, how confidence in memories is used in decision making is unknown. We developed a spatial memory task in which rats were incentivized to gamble their time: betting more following a correct choice yielded greater reward. Rat behavior reflected memory confidence, with higher temporal bets following correct choices. We applied machine learning to identify a memory decision variable and built a generative model of memories evolving over time that accurately predicted both choices and confidence reports. Our results reveal in rats an ability thought to exist exclusively in primates and introduce a unified model of memory dynamics, retrieval, choice, and confidence