885 research outputs found
\u3ci\u3eLevisunguis subaequalis\u3c/i\u3e n. g., n. sp., a Tongue Worm (Pentastomida: Porocephalida: Sebekidae) Infecting Softshell Turtles, \u3ci\u3eApalone\u3c/i\u3e spp. (Testudines: Trionychidae), in the Southeastern United States
A new tongue worm (Pentastomida) belonging to the Sebekidae Sambon, 1922 (Porocephaloidea Sambon, 1922) is described based on exemplars collected from softshell terrapins Apalone spinifera aspera (Agassiz) and Apalone ferox (Schneider) in the southeastern United States; a new genus is erected to accommodate the new species. The new species belongs in the Sebekidae because adults possess four simple hooks arranged in a trapezoid pattern on the ventral surface of the cephalothorax, a mouth opening between the anterior and posterior pairs of hooks, a terminal anus, an elongated uterus with preanal uterine pore, and a Y-shaped seminal vesicle. Nymphs possess geminate hooks, and the new species has an aquatic life cycle in which nymphs become encapsulated in the body cavity of a freshwater fish and mature in the lungs of a terrapin. The new genus is distinct from other genera in the Sebekidae primarily by differences in hook morphology and the fact that representatives use a terrapin as a definitive host. Nymphs infecting fish and presumed to be the new species matured as postlarval juveniles conspecific with the new species when they were fed to the eastern mud turtle, Kinosternon subrubrum (LacépÚde). Nymphs of the new species are anatomically similar to but larger than nymphs of Sebekia mississippiensis Overstreet, Self & Vliet, 1985 found in the mesentery of fishes captured in Florida, USA. Adults of the new species differ from those of S. mississippiensis based on hook features, chloride cell pore pattern on annuli, body size, and use of a turtle rather than crocodilian definitive host. The new species is the third North American member of the Sebekidae
A Cu2+ (S = 1/2) Kagom\'e Antiferromagnet: MgxCu4-x(OH)6Cl2
Spin-frustrated systems are one avenue for inducing macroscopic quantum
states in materials. However, experimental realization of this goal has been
difficult because of the lack of simple materials and, if available, the
separation of the unusual magnetic properties arising from exotic magnetic
states from behavior associated with chemical disorder, such as site mixing.
Here we report the synthesis and magnetic properties of a new series of
magnetically frustrated materials, MgxCu4-x(OH)6Cl2. Because of the
substantially different ligand-field chemistry of Mg2+ and Cu2+, site disorder
within the kagom\'e layers is minimized, as directly measured by X-ray
diffraction. Our results reveal that many of the properties of these materials
and related systems are not due to disorder of the magnetic lattice but rather
reflect an unusual ground state.Comment: Accepted for publication in J. Am. Chem. Soc
The heart of Rett syndrome: A quantitative analysis of cardiac repolarization
BACKGROUND: Rett syndrome (RTT) is a developmental encephalopathy disorder that is associated with a high incidence of sudden death presumably from cardiorespiratory etiologies. Electrocardiogram (ECG) abnormalities, such as prolonged heart-rate corrected QT (QTc) interval, are markers of cardiac repolarization and are associated with potentially lethal ventricular arrhythmias. This study investigates the cardiac repolarization characteristics of RTT patients, including QTc and T-wave morphology characteristics.
METHODS: A retrospective quantitative analysis on 110 RTT patients and 124 age and sex-matched healthy controls was conducted.
RESULTS: RTT patients had longer QTc, more abnormal T-wave morphology, and greater heterogeneity of cardiac repolarization parameters compared to controls. Even RTT patients without prolonged QTc had more abnormal ECG and T-wave characteristics than controls. Among RTT patients,
CONCLUSIONS: Cardiac repolarization abnormalities are present in RTT patients, even without long QTc. T-wave morphology is related to RTT genotype and may be predictive of mortality. These findings could be used to help the management and monitoring of RTT patients
The kinematic identification of a thick stellar disc in M31
We present the first characterization of a thick disc component in the
Andromeda galaxy (M31) using kinematic data from the DEIMOS multi-object
spectrograph instrument on Keck II. Using 21 fields in the South West of the
galaxy, we measure the lag of this component with respect to the thin disc, as
well as the dispersion, metallicity and scale length of the component. We find
an average lag between the two components of =46.0+/-3.9km/s. The velocity
dispersion of the thick disc is sigma_{thick}=50.8+/-1.9km/s, greater than the
value of dispersion we determine for the thin disc,
sigma_{thin}=35.7+/-1.0km/s. The thick disc is more metal poor than the thin
disc, with [Fe/H]_{spec}=-1.0+/-0.1 compared to [Fe/H]_{spec}=-0.7+/-0.05 for
the thin disc. We measure a radial scale length of the thin and thick discs of
h_r=7.3+/-1.0 kpc and h_r=8.0+/-1.2 kpc. From this, we infer scale heights for
both discs of 1.1+/-0.2 kpc and 2.8+/-0.6 kpc, both of which are ~2--3 times
larger than those observed in the Milky Way. We estimate a mass range for the
thick disc component of 2.4x10^{10}Msun< M_{*,thick} <4.1x10^{10}Msun. This
value provides a useful constraint on possible formation mechanisms, as any
proposed method for forming a thick disc must be able to heat (or deposit) at
least this amount of material.Comment: 22 pages, 17 figures. Minor revisions made to text following referee
report. Accepted for publication in MNRA
Approaching public perceptions of datafication through the lens of inequality: a case study in public service media
In the emerging field of critical data studies, there is increasing acknowledgement that the negative effects of datafication are not experienced equally by all. Research on data and discrimination in particular has highlighted how already socially unequal populations are discriminated against in data-driven systems. Elsewhere, there is growing interest in public perceptions of datafication, amongst academic researchers interested in producing âbottom upâ understandings of the new roles of data in society and non-academic stakeholders keen to
establish positive perceptions of data-driven systems. However, research into public perceptions rarely engages with the issue of inequality which is so central in data and discrimination
scholarship. Bringing these two issues together, this paper explores public perceptions of datafication through the lens of inequality, focusing on the relationship between understandings
and feelings within these perceptions. The paper draws on empirical focus group research into how audiences perceive the data practices that signing in to access BBC digital services enable. The paper shows how inequalities relating to age, dis/ability, poverty and their intersections played a role in shaping perceptions and that these social inequalities informed understandings of and feelings about data practices in complex and diverse ways. It concludes with reflections on the significance of these findings for future research and for data-related policy
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