scholarly journals The braincase ofMesosuchus browni(Reptilia, Archosauromorpha) with information on the inner ear and description of a pneumatic sinus

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6798 ◽  
Author(s):  
Gabriela Sobral ◽  
Johannes Müller
Keyword(s):  
Low Frequency ◽  
Semicircular Canals ◽  
Terrestrial Ecosystems ◽  
Micro Computed Tomography ◽  
Gaze Stabilization ◽  
New Information ◽  
Computed Tomography Scanning ◽  
The Right ◽  
First Time

Rhynchosauria is a group of archosauromorph reptiles abundant in terrestrial ecosystems of the Middle Triassic.Mesosuchusis one of the earliest and basalmost rhynchosaurs, playing an important role not only for the understanding of the evolution of the group as a whole, but also of archosauromorphs in general. The braincase ofMesosuchushas been previously described, albeit not in detail, and the middle and inner ears were missing. Here, we provide new information based on micro-computed tomography scanning of the best-preserved specimen ofMesosuchus, SAM-PK-6536. Contrary to what has been stated previously, the braincase ofMesosuchusis dorso-ventrally tall. The trigeminal foramen lies in a deep recess on the prootic whose flat ventral rim could indicate the articulation surface to the laterosphenoid, although no such element was found. The middle ear ofMesosuchusshows a small and deeply recessed fenestra ovalis, with the right stapes preserved in situ. It has a rather stout, imperforated and posteriorly directed shaft with a small footplate. These features suggest that the ear ofMesosuchuswas well-suited for the detection of low-frequency sounds. The semicircular canals are slender and elongate and the floccular fossa is well-developed. This is indicative of a refined mechanism for gaze stabilization, which is usually related to non-sprawling postures. The most striking feature of theMesosuchusbraincase is, however, the presence of a pneumatic sinus in the basal tubera. The sinus is identified as originating from the pharyngotympanic system, implying ossified Eustachian tubes. Braincase pneumatization has not yet been a recognized feature of stem-archosaurs, but the potential presence of pneumatic foramina in an array of taxa, recognized here as such for the first time, suggests braincase sinuses could be present in many other archosauromorphs.

scholarly journals New information on the braincase and inner ear of Euparkeria capensis Broom: implications for diapsid and archosaur evolution

2016 ◽  
Vol 3 (7) ◽  
pp. 160072 ◽  
Author(s):  
Gabriela Sobral ◽  
Roland B. Sookias ◽  
Bhart-Anjan S. Bhullar ◽  
Roger Smith ◽  
Richard J. Butler ◽  
...  
Keyword(s):  
Lateral View ◽  
Micro Computed Tomography ◽  
Active Lifestyle ◽  
Pressure Relief ◽  
New Information ◽  
Computed Tomography Scanning ◽  
Anterior Semicircular Canal ◽  
First Time ◽  
Tomography Scanning ◽  
Hearing System

Since its discovery, Euparkeria capensis has been a key taxon for understanding the early evolution of archosaurs. The braincase of Euparkeria was described based on a single specimen, but much uncertainty remained. For the first time, all available braincase material of Euparkeria is re-examined using micro-computed tomography scanning. Contrary to previous work, the parabasisphenoid does not form the posterior border of the fenestra ovalis in lateral view, but it does bear a dorsal projection that forms the anteroventral half of the fenestra. No bone pneumatization was found, but the lateral depression of the parabasisphenoid may have been pneumatic. We propose that the lateral depression likely corresponds to the anterior tympanic recess present in crown archosaurs. The presence of a laterosphenoid is confirmed for Euparkeria . It largely conforms to the crocodilian condition, but shows some features which make it more similar to the avemetatarsalian laterosphenoid. The cochlea of Euparkeria is elongated, forming a deep cochlear recess. In comparison with other basal archosauromorphs, the metotic foramen is much enlarged and regionalized into vagus and recessus scalae tympani areas, indicating an increase in its pressure-relief mechanism. The anterior semicircular canal is extended and corresponds to an enlarged floccular fossa. These aspects of the braincase morphology may be related to the development of a more upright posture and active lifestyle. They also indicate further adaptations of the hearing system of Euparkeria to terrestriality.

scholarly journals A census of the pulsar population observed with the international LOFAR station FR606 at low frequencies (25–80 MHz)

2020 ◽  
Vol 635 ◽  
pp. A76 ◽  
Author(s):  
L. Bondonneau ◽  
J.-M. Grießmeier ◽  
G. Theureau ◽  
A. V. Bilous ◽  
V. I. Kondratiev ◽  
...  
Keyword(s):  
Low Frequency ◽  
Frequency Range ◽  
Radio Pulsars ◽  
Low Frequencies ◽  
Radio Observatory ◽  
Future Studies ◽  
New Information ◽  
Upper Limits ◽  
Widespread Phenomenon ◽  
First Time

Context. To date, only 69 pulsars have been identified with a detected pulsed radio emission below 100 MHz. A LOFAR-core LBA census and a dedicated campaign with the Nançay LOFAR station in stand-alone mode were carried out in the years 2014–2017 in order to extend the known population in this frequency range. Aims. In this paper, we aim to extend the sample of known radio pulsars at low frequencies and to produce a catalogue in the frequency range of 25–80 MHz. This will allow future studies to probe the local Galactic pulsar population, in addition to helping explain their emission mechanism, better characterising the low-frequency turnover in their spectra, and obtaining new information about the interstellar medium through the study of dispersion, scattering, and scintillation. Methods. We observed 102 pulsars that are known to emit radio pulses below 200 MHz and with declination above −30°. We used the Low Band Antennas (LBA) of the LOw Frequency ARray (LOFAR) international station FR606 at the Nançay Radio Observatory in stand-alone mode, recording data between 25 and 80 MHz. Results. Out of our sample of 102 pulsars, we detected 64. We confirmed the existence of ten pulsars detected below 100 MHz by the LOFAR LBA census for the first time (Bilous et al. 2020, A&A, 635, A75) and we added two more pulsars that had never before been detected in this frequency range. We provided average pulse profiles, DM values, and mean flux densities (or upper limits in the case of non-detections). The comparison with previously published results allows us to identify a hitherto unknown spectral turnover for five pulsars, confirming the expectation that spectral turnovers are a widespread phenomenon.

RF-Magnetron Sputtered Strontium Titanate: Structure, Processing and Property Relationships

1999 ◽  
Vol 603 ◽  
Author(s):  
B.J. Gibbons ◽  
Y. Fan ◽  
A.T. Findikoglu ◽  
D.W. Reagor ◽  
Q.X. Jia
Keyword(s):  
Room Temperature ◽  
Low Frequency ◽  
Ozone Treatment ◽  
X Ray Diffraction ◽  
X Ray ◽  
Treated Sample ◽  
Diffraction Peaks ◽  
Compositional Variations ◽  
First Time

AbstractThe low frequency dielectric properties of epitaxial SrTiO3 thin films deposited on LaAlO3 are presented. The films were deposited using radio-frequency magnetron sputtering from stoichiometric targets in an Ar/O2 atmosphere. For the first time, the effects of in situ ozone annealing during the early stages of deposition were explored. X-ray diffraction results indicated that the ozone treatment resulted in more symmetric and sharper diffraction peaks (2 Θ- FWHM decreased from 0.17° to 0.10°). In addition, the peaks for the ozone treated samples were shifted in 2 Θ towards values approaching the bulk value. Rutherford backscattering measurements showed Sr/Ti ratios of 1:1 for these samples, indicating these peak shifts are not due to compositional variations. The dielectric constant of the ozone treated samples increased from 275 at room temperature to 1175 at 22 K (measured at 100 kHz). The effective loss tangent of the device remained between 1 × 10−4 and 1 × 10−3 down to 100 K, where it began to increase. The tunability was also measured. The ozone treated sample showed tunability of 46%, 43% and 38% at 22 K, 40 K and 60 K, respectively. Finally, similar measurements were completed at 1 MHz, indicating a minimal dependence of these properties on frequencies in this range.

Long-Term Inhibition of Return of Attention

2003 ◽  
Vol 14 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Steven P. Tipper ◽  
Sarah Grison ◽  
Klaus Kessler
Keyword(s):  
Inhibition Of Return ◽  
Right Hemisphere ◽  
New Information ◽  
Memory Representations ◽  
Efficient Processing ◽  
Exogenous Cue ◽  
Face Stimuli ◽  
The Right ◽  
First Time

During search of the environment, the inhibition of the return (IOR) of attention to already-examined information ensures that the target will ultimately be detected. Until now, inhibition was assumed to support search of information during one processing episode. However, in some situations search may have to be completed long after it was begun. We therefore propose that inhibition can be associated with an episode encoded into memory such that later retrieval reinstates inhibitory processing and encourages examination of new information. In two experiments in which attention was drawn to face stimuli with an exogenous cue, we demonstrated for the first time the existence of long-term IOR. Interestingly, this was the case only for faces in the left visual field, perhaps because more efficient processing of faces in the right hemisphere than the left hemisphere results in richer, more retrievable memory representations.

Congenital cholesteatoma of mastoid origin

2007 ◽  
Vol 121 (11) ◽  
Author(s):  
J H Lee ◽  
S J Hong ◽  
C H Park ◽  
S H Jung
Keyword(s):  
Posterior Fossa ◽  
External Auditory Canal ◽  
Semicircular Canals ◽  
Posterior Wall ◽  
Sigmoid Sinus ◽  
Mastoid Cavity ◽  
Congenital Cholesteatoma ◽  
Computed Tomography Scanning ◽  
History Of ◽  
The Right

AbstractObjective:We report an extremely rare case of congenital cholesteatoma of mastoid origin.Case report:A male patient was admitted with a one-month history of dizziness and headache, plus tinnitus in the right ear. Computed tomography scanning of the temporal bone showed destruction of the posterior wall of the external auditory canal by a lesion of soft tissue density in the right mastoid cavity, and also destruction of the bony plates of the posterior fossa and the sigmoid sinus, and of the mastoid tegmen. During surgery, a huge cholesteatoma sac was observed in the mastoid cavity, containing a large amount of keratinous material. The tegmen mastoideum and the bony plates of the posterior fossa and the sigmoid sinus were also observed to be destroyed. The skin and the tympanic membrane of the external auditory canal were intact, and the middle ear and aditus ad antrum mucosa were normal. The huge cholesteatoma sac was completely excised via a partial translabyrinthine approach, eradicating the superior and posterior semicircular canals.Conclusion:This case of congenital cholesteatoma of mastoid origin was diagnosed by clinical examination, radiological evaluation and surgical findings.

Molecular relaxation in Chitosan films in GHz frequency range

2014 ◽  
Vol 1613 ◽  
pp. 83-88
Author(s):  
Siva Kumar-Krishnan ◽  
Evgen Prokhorov ◽  
Gabriel Luna-Barcenas
Keyword(s):  
Activation Energy ◽  
Low Frequency ◽  
Bound Water ◽  
Wide Frequency Range ◽  
Frequency Range ◽  
Temperature Range ◽  
A Value ◽  
Chitosan Films ◽  
First Time

ABSTRACTThe molecular relaxations behavior of chitosan (CS) films in the wide frequency range of 0.1-3x109 Hz (by using three different impedance analyzers) have been investigated in the temperature range of -100C to 120°C using Dielectric Spectroscopy (DS). Additionally to the low frequency molecular relaxations such as α and β relaxations, for the first time, high frequency (1-3 GHz) relaxation process has been observed in the chitosan films. This relaxation exhibits Arrhenius-type dependence in the temperature range of -100 C to 54°C with negative activation energy -2.7 kJ/mol. At temperatures above 54°C, the activation energy changes from -2.7 kJ/mol to +4.4 kJ/mol. Upon cooling, the activation energy becomes negative again with a value of -1.2 kJ/mol. The bound water between chitosan molecules strongly modifies molecular motion and the relaxation spectrum, giving rise to a new relaxation at the frequency at ca. 1 GHz. In situ FTIR analysis has shown that this relaxation related to the changes in vibration of the –OH, NH and –CO functional groups.

scholarly journals Penetrative and non-penetrative interaction between Laboulbeniales fungi and their arthropod hosts

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ana Sofia P. S. Reboleira ◽  
Leif Moritz ◽  
Sergi Santamaria ◽  
Henrik Enghoff
Keyword(s):  
Insect Host ◽  
Micro Computed Tomography ◽  
Key Factors ◽  
Complete Structure ◽  
Entire Life ◽  
Entire Life Cycle ◽  
Visible Part ◽  
Animal Interaction ◽  
First Time

AbstractLaboulbeniales are a highly specialized group of fungi living only on arthropods. They have high host specificity and spend their entire life-cycle on an arthropod host. Taxonomic characters of Laboulbeniales are based on the architecture of the cells of the parenchymal thallus, i.e. the visible part of the fungus outside the host. The extent of the fungus spreading inside the host—the haustorium—remains largely unknown. The attachment to the arthropod host is fundamental to understand the fungus-animal interaction, but how this truly occurs is unclear. Recent evidences question the strictly parasitic life-style of Laboulbeniales. We used micro-computed tomography (µCT) and 3D reconstructions to visualize, for the first time, the complete structure of Laboulbeniales species in situ on their hosts. We compared the haustoriate species, Arthrorhynchus nycteribiae on an insect host to the non-haustoriate species, Rickia gigas on a millipede host. Our results confirm that some Laboulbeniales species are ectoparasitic and have a haustorial structure that penetrates the host’s cuticle, while others are ectobionts and are only firmly attached to the host’s cuticle without penetrating it. The presence and the morphology of the haustorium are important traits for Laboulbeniales evolution, and key factors for future understanding of host dependence and specificity.

scholarly journals Coordinated observation of field line resonance in the mid-tail

2006 ◽  
Vol 24 (2) ◽  
pp. 707-723 ◽  
Author(s):  
Y. Zheng ◽  
A. T. Y. Lui ◽  
I. R. Mann ◽  
K. Takahashi ◽  
J. Watermann ◽  
...  
Keyword(s):  
Field Line ◽  
Low Frequency ◽  
Field Measurements ◽  
Early Morning ◽  
Field Line Resonance ◽  
Cluster Data ◽  
Line Resonance ◽  
Field Lines ◽  
First Time

Abstract. Standing Alfvén waves of 1.1 mHz (~15 min in period) were observed by the Cluster satellites in the mid-tail during 06:00-07:00 UT on 8 August 2003. Pulsations with the same frequency were also observed at several ground stations near Cluster's footpoint. The standing wave properties were determined from the electric and magnetic field measurements of Cluster. Data from the ground magnetometers indicated a latitudinal amplitude and phase structure consistent with the driven field line resonance (FLR) at 1.1 mHz. Simultaneously, quasi-periodic oscillations at different frequencies were observed in the post-midnight/early morning sector by GOES 12 (l0≈8.7), Polar (l0≈11-14) and Geotail (l0≈9.8). The 8 August 2003 event yields rare and interesting datasets. It provides, for the first time, coordinated in situ and ground-based observations of a very low frequency FLR in the mid-tail on stretched field lines.

The Occlusion Effect in Unilateral Functional Hearing Loss

1970 ◽  
Vol 13 (1) ◽  
pp. 37-40
Author(s):  
Gary Thompson ◽  
Marie Denman
Keyword(s):  
Hearing Loss ◽  
Bone Conduction ◽  
Low Frequency ◽  
Clinical Implications ◽  
The Right ◽  
Occlusion Effect

Bone-conduction tests were administered to subjects who feigned a hearing loss in the right ear. The tests were conducted under two conditions: With and without occlusion of the non-test ear. It was anticipated that the occlusion effect, a well-known audiological principle, would operate to draw low frequency bone-conducted signals to the occluded side in a predictable manner. Results supported this expectation and are discussed in terms of their clinical implications.

Why Has There Been No People’s Power Rebellion in North Korea?

2018 ◽  
pp. 1-34
Author(s):  
Andrew Jackson
Keyword(s):  
Rural Areas ◽  
North Korea ◽  
Large Scale ◽  
Political Elite ◽  
Information Control ◽  
Al Jazeera ◽  
The North ◽  
New Information ◽  
Effective System ◽  
The Right

One scenario put forward by researchers, political commentators and journalists for the collapse of North Korea has been a People’s Power (or popular) rebellion. This paper analyses why no popular rebellion has occurred in the DPRK under Kim Jong Un. It challenges the assumption that popular rebellion would happen because of widespread anger caused by a greater awareness of superior economic conditions outside the DPRK. Using Jack Goldstone’s theoretical expla-nations for the outbreak of popular rebellion, and comparisons with the 1989 Romanian and 2010–11 Tunisian transitions, this paper argues that marketi-zation has led to a loosening of state ideological control and to an influx of infor-mation about conditions in the outside world. However, unlike the Tunisian transitions—in which a new information context shaped by social media, the Al-Jazeera network and an experience of protest helped create a sense of pan-Arab solidarity amongst Tunisians resisting their government—there has been no similar ideology unifying North Koreans against their regime. There is evidence of discontent in market unrest in the DPRK, although protests between 2011 and the present have mostly been in defense of the right of people to support themselves through private trade. North Koreans believe this right has been guaranteed, or at least tacitly condoned, by the Kim Jong Un government. There has not been any large-scale explosion of popular anger because the state has not attempted to crush market activities outright under Kim Jong Un. There are other reasons why no popular rebellion has occurred in the North. Unlike Tunisia, the DPRK lacks a dissident political elite capable of leading an opposition movement, and unlike Romania, the DPRK authorities have shown some flexibility in their anti-dissent strategies, taking a more tolerant approach to protests against economic issues. Reduced levels of violence during periods of unrest and an effective system of information control may have helped restrict the expansion of unrest beyond rural areas.

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