9,158 research outputs found
A new deep-sea pennatulacean (Anthozoa: Octocorallia: Chunellidae) from the Porcupine Abyssal Plain (NE Atlantic)
During the BENGAL cruises, an important
collection of deep-sea benthic organisms was sampled.
Among the pennatulacean colonies, a previously undescribed species of chunellid was collected. That material
is here described as the type species of a new genus,
Porcupinella gen. nov. The new genus and species are
described based on material collected in the Porcupine
Abyssal Plain (NE Atlantic), 4,839–4,847 m in depth. This
is the first time that a chunellid is reported from the
Atlantic Ocean. The new genus is compared with the other
genera in the family, and some phylogenetic remarks about
the families Chunellidae and Umbellulidae are also
provided
PROTECTING THE RIGHT TO BE LET ALONE POST DOBBS: A STATE CONSTITUTIONAL STRATEGY
In Dobbs v. Jackson Women’s Health Organization, the United States Supreme Court held that the federal constitution allows states to interfere with, or even deny, the right of women to choose whether to carry a pregnancy to term.1 This essay argues that state constitutional guarantees of the right to privacy protect that right. It further argues that advocates in states that do not have a constitutional right to privacy should utilize direct democracy provisions, where available, to add a right to privacy to their constitutions
Returns to Soybean Producers from Investments in Promotion and Research
U.S. soybean producers have been cooperatively investing in both production research and demand promotion for nearly four decades to enhance the profitability and international competitiveness of their industry. Have producers benefitted from their contributions to soybean checkoff program activities over the years? How has the return to investments in soybean production research compared to that of soybean demand promotion investments? The overall positive returns to producers over the study period resulted primarily from promotion activities. Production research contributed negatively to overall producer returns from soybean checkoff investments.Agribusiness,
Vortex Fluctuations in the Critical Casimir Effect of Superfluid and Superconducting Films
Vortex-loop renormalization techniques are used to calculate the magnitude of
the critical Casimir forces in superfluid films. The force is found to become
appreciable when size of the thermal vortex loops is comparable to the film
thickness, and the results for T < Tc are found to match very well with
perturbative renormalization theories that have only been carried out for T >
Tc. When applied to a high-Tc superconducting film connected to a bulk sample,
the Casimir force causes a voltage difference to appear between the film and
bulk, and estimates show that this may be readily measurable.Comment: 4 pages, 5 figures, Revtex 4, typo correctio
Neuroendocrine Pathways Mediating Nutritional Acceleration of Puberty: Insights from Ruminant Models
The pubertal process is characterized by an activation of physiological events within the hypothalamic-adenohypophyseal–gonadal axis which culminate in reproductive competence. Excessive weight gain and adiposity during the juvenile period is associated with accelerated onset of puberty in females. The mechanisms and pathways by which excess energy balance advances puberty are unclear, but appear to involve an early escape from estradiol negative feedback and early initiation of high-frequency episodic gonadotropin-releasing hormone (GnRH) secretion. Hypothalamic neurons, particularly neuropeptide Y and proopiomelanocortin neurons are likely important components of the pathway sensing and transmitting metabolic information to the control of GnRH secretion. Kisspeptin neurons may also have a role as effector neurons integrating metabolic and gonadal steroid feedback effects on GnRH secretion at the time of puberty. Recent studies indicate that leptin-responsive neurons within the ventral premammillary nucleus play a critical role in pubertal progression and challenge the relevance of kisspeptin neurons in this process. Nevertheless, the nutritional control of puberty is likely to involve an integration of major sensor and effector pathways that interact with modulatory circuitries for a fine control of GnRH neuron function. In this review, observations made in ruminant species are emphasized for a comparative perspective
Crystallization of dense binary hard-sphere mixtures with marginal size ratio
Molecular dynamics simulations are performed for binary hard-sphere mixtures with a size ratio of γ=0.9 and a volume fraction of ϕ=0.58 over a range of compositions. We show how, at this high volume fraction, crystallization depends sensitively on the composition. Evidence is presented that crystallization in these mixtures does not proceed by the standard nucleation and growth paradigm. Rather, some crystallite forms almost immediately and then an interplay between compositional fluctuations and crystal growth is able to dramatically extend the time scale on which further crystallization occurs. This can be seen as a form of geometric frustration
Merged ionization/dissociation fronts in planetary nebulae
The hydrogen ionization and dissociation front around an ultraviolet
radiation source should merge when the ratio of ionizing photon flux to gas
density is sufficiently low and the spectrum is sufficiently hard. This regime
is particularly relevant to the molecular knots that are commonly found in
evolved planetary nebulae, such as the Helix Nebula, where traditional models
of photodissociation regions have proved unable to explain the high observed
luminosity in H_2 lines. In this paper we present results for the structure and
steady-state dynamics of such advection-dominated merged fronts, calculated
using the Cloudy plasma/molecular physics code. We find that the principal
destruction processes for H_2 are photoionization by extreme ultraviolet
radiation and charge exchange reactions with protons, both of which form H_2^+,
which rapidly combines with free electrons to undergo dissociative
recombination. Advection moves the dissociation front to lower column densities
than in the static case, which vastly increases the heating in the partially
molecular gas due to photoionization of He^0, H_2, and H^0. This causes a
significant fraction of the incident bolometric flux to be re-radiated as
thermally excited infrared H_2 lines, with the lower excitation pure rotational
lines arising in 1000 K gas and higher excitation H_2 lines arising in 2000 K
gas, as is required to explain the H_2 spectrum of the Helix cometary knots.Comment: 4 pages, accepted by ApJL, scheduled December 20 issu
Octocorals in the Galapagos Islands
The Galapagos octocorals were almost unknown until recent years. Of the three orders within the subclass Octocorallia (Anthozoa, Cnidaria), the Pennatulacea (sea pens) and Alcyonacea (soft corals and gorgonians) occur in the Galapagos. Recent collections and research bring the total known octocorallian fauna to three sea pens (Virgularia galapagensis, Ptilosarcus undulatus and Cavernulina darwini) and 15 gorgonians. Of the 13 gorgonians that we have collected, several are new species. Pacifigorgia is widely distributed in the archipelago, with four named species (P. dampieri, P. symbiotica, P. rubripunctata, and P. darwinii), three of them recently described, and two others yet to be described. The genus Muricea contains three widely distributed undescribed species, one of which appears in three chromotypes, and one deepwater species that has not been collected recently. Two species of Heterogorgia occur in the central archipelago, H. verrucosa and the recently described and widely distributed H. hickmani. The remaining gorgonians are Eugorgia daniana, Leptogorgia alba and Adelogorgia telones
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