Throat Structure Research Articles

Rostral and caudal pharyngeal arches share a common neural crest ground pattern.

In vertebrates, face and throat structures, such as jaw, hyoid and thyroid cartilages develop from a rostrocaudal metameric series of pharyngeal arches, colonized by cranial neural crest cells (NCCs). Colinear Hox gene expression patterns underlie arch specific morphologies, with the exception of the first (mandibular) arch, which is devoid of any Hox gene activity. We have previously shown that the first and second (hyoid) arches share a common, Hox-free, patterning program. However, whether or not more posterior pharyngeal arch neural crest derivatives are also patterned on the top of the same ground-state remained an unanswered question. Here, we show that the simultaneous inactivation of all Hoxa cluster genes in NCCs leads to multiple jaw and first arch-like structures, partially replacing second, third and fourth arch derivatives, suggesting that rostral and caudal arches share the same mandibular arch-like ground patterning program. The additional inactivation of the Hoxd cluster did not significantly enhance such a homeotic phenotype, thus indicating a preponderant role of Hoxa genes in patterning skeletogenic NCCs. Moreover, we found that Hoxa2 and Hoxa3 act synergistically to pattern third and fourth arch derivatives. These results provide insights into how facial and throat structures are assembled during development, and have implications for the evolution of the pharyngeal region of the vertebrate head.

3D image-based characterization of fluid displacement in a Berea core

Improved network flow models require the incorporation of increasingly accurate geometrical characterization of the microscale pore structure as well as greater information on fluid–fluid interaction (interfaces) at pore scales. We report on three dimensional (3D) pore scale medium characterization, absolute permeability computations for throat structures, and pore scale residual fluid distribution in a Berea core. X-ray computed microtomography combined with X-ray attenuating dopants is used to obtain 3D images of the pore network and to resolve phase distributions in the pore space. We present results on pore characterization, including distributions for pore volume, pore surface area, throat surface area, and principal direction diameters for pores and throats. Lattice Boltzmann computations are used to predict absolute permeabilities for individual throats reconstructed from the images. We present results on oil and water distribution in the pore space at residual conditions. We also consider the effects on residual fluid distribution due to the injection and gelation of a water-based gel. In extensive studies of Berea cores it has been observed that introducing water-based gels in the displacement process reduces permeability to water more than to oil. Our results provide supporting evidence for the involvement of gel compaction (dehydration) and oil trapping, while discounting gel blockage in throats, as mechanisms contributing to this effect.

An Improved Method of Using NMR T2Distribution to Evaluate Pore Size Distribution

Both NMR T2 distribution of core and capillary pressure can be used to characterize pore throat structures of rock to a certain degree. Theoretical analysis gives the correlation between these two sets of data. In order to utilize NMR spectra to study rock pore throat structure, the key step is to determine the transferring coefficient between T2 and pc since they are correlated. In the previous methods, the capillary pressure curve obtained by using T2 distribution has a poor match relationship with the real capillary pressure curves. In fact, due to the existence of membrane bound-water, the core space determined by T2 distribution is different from that determined by capillary pressure curves. This work proposes an improved method which uses free-water T2 distribution to construct capillary pressure curves after eliminating membrane bound-water's contribution to T2 distribution. Applying this method to some core data we make some analyses and comparisons. The result shows an improved precision and indicates that this method can provide reliable principle and methodological support to evaluation of pore structure by using T2 distribution.

Special report: Reassessment of the ORL–HNS workforce: Perceptions and realities

Objective This Workforce Study re-examined the current scope and geographic distribution of Otolaryngology practice and assessed the otolaryngologists' role in relation to other specialists in the diagnosis and treatment of disorders of the ear, nose, throat, and related structures of the head and neck. Study design A national survey and review of federal, corporate and administrative databases, coupled wih a focus group of otolaryngologists, were analyzed to compile physician manpower figures, state and regional demographic data, and prediction modeling of Managed Care and FFS environments. Results The current and predicted workforce supply and demographic data support a geographic and proportionate increase in the number of otolaryngologists practicing and entering the workforce. Additional findings involving the role of the specialty specifically identified an increase in the treatment of allergic disease within the Managed Care sector and a diminution of the gatekeeper concept. Demographic findings represent a stable age distribution of 40 to 49 and 50 to 59 year old otolaryngologists, with a noted increase in the number of women entering the field. Empiric data reflects the continuous, diverse and dominant role otolaryngologists maintain in the treatment and care of patients with otolaryngic and head and neck disease. Conclusions This study continues the effort to identify otolaryngology workforce demographic profiles and make recommendations for a future national practice model. Continuous reassessment of the specialty is required.

Understanding endothelin-1 function during craniofacial development in the mouse and zebrafish.

Morphogenesis of the face and neck is driven by an intricate relay of signaling molecules and transcription factors organized into hierarchical pathways. The coordinated action of these pathways regulates the development of neural crest cells within the pharyngeal arches, resulting in proper spatiotemporal formation of bone, cartilage, and connective tissue. While the functions of many genes involved in these processes were initially elucidated through the use of knockout technology in the mouse, increasing numbers of zebrafish craniofacial mutants have led to a rapid expansion in the identification of genes involved in craniofacial development. A comparative analysis of signaling pathways involved in these processes between mouse and zebrafish holds the potential not only to pinpoint conserved and therefore crucial gene functions in craniofacial development, but also to rapidly identify and study downstream effectors. These complementary approaches will also allow rapid identification of candidate genes and gene functions disrupted in human craniofacial dysmorphologies. In this brief review, we present a comparative analysis of one molecule involved in craniofacial development, endothelin-1, a small, secreted protein that is crucial for patterning the neural crest cells that give rise to lower jaw and throat structures.

Design considerations for single-pole-type write heads

We investigated the single-pole-type write head for perpendicular recording by using a commercial three-dimensional finite-element magnetostatic solver in conjunction with micromagnetic simulation. We studied head parameters such as throat height and structure, return pole air-bearing surface dimensions, yoke dimensions, and coil type (solenoid or planar), and we varied the anisotropy variance of the media. Finite-element method simulations show that a tradeoff between maximum field and gradients must be made because of the structure of the pole-tip region. Micromagnetic simulations show tribit patterns and the detrimental effect of anisotropy value variations in the media.

Impairment Tutorial: Impairment Evaluation of Ear, Nose, Throat, and Related Structures: Fifth Edition Revisions

Abstract Chapter 11, Ear, Nose, Throat, and Related Structures of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fifth Edition, includes a new section on voice impairment, a new table on vestibular disorders, and information regarding combined facial disorders and disfigurements. Impairments are based on anatomic, physiological, and functional approaches and involve the assessment of subjective information (eg, statements provided by the patient) and objective factors determined by clinical examination or functional tests. The rating of hearing loss is unchanged from the Fourth Edition in the AMA Guides, Fifth Edition, and tables guide the conversion of monoauricular and binaural hearing impairments into whole person impairments. A tinnitus rating can be combined with the binaural hearing impairment loss before conversion to a whole person permanent impairment. Total disfigurement of the face can be graded between 16% and 50%; a table guides evaluators in rating facial disorders or disfigurement. Impairments of the nose, throat, and related structures include respiration, mastication, deglutition, olfaction and taste, speech, and voice. Although hearing loss is measured using anatomic, physiological, and functional approaches, many other assessments in Chapter 11 are based on interference in the activities of daily living, and the examiner must perform a careful assessment and apply the criteria in the AMA Guides.

Impairment Tutorial: Rating Cranial Nerve and Spinal Cord Disorders

Abstract The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fourth Edition, discusses rating cranial nerve and spinal cord impairments. Evaluation of impairment of the cranial nerves is based on clinical neurological assessment, and many cranial nerves also are addressed in other chapters of the AMA Guides (eg, the visual system or the ear, nose, and throat). With respect to cranial nerve I, an impairment estimate associated with anosmia or parosmia should be given only if this significantly interferes with daily activities. For cranial nerve II, the AMA Guides recommends ophthalmologic testing of visual fields and best correction. For cranial nerves III, IV, and VI, the reader is referred to section 8.3, and, for cranial nerve V, the AMA Guides provides a method of determining impairment associated with trigeminal neuralgia. A table provides data regarding impairment for conditions that affect the seventh cranial (facial) nerve; sensory loss related to the facial nerve does not interfere with activities of daily living. Auditory impairment (cranial nerve VIII) is rated according to criteria in the ear, nose, throat, and related structures chapter, including tinnitus. Cranial nerves IX, X, XI, and XII are involved in breathing, swallowing, speaking, and some visceral functions, and ratings criteria are presented. In terms of spinal cord impairments, the AMA Guides divides pathology into six categories: station and gait; use of the upper extremities; respiration; urinary bladder function; anorectal function; and sexual function.

NON-ABELIAN TOPOLOGICAL SOLUTIONS IN STRINGY GRAVITY

Non-Abelian solutions of the low-energy heterotic string effective action are discussed. Three types of solutions are shown to exist: regular uncharged shaleron-like solutions, uncharged non-Abelian black holes and charged black holes with non-Abelian hair. In the extremal limit charged non-Abelian black holes generate regular throat structure in the string frame similar to that of the Gibbons-Maeda-Horowitz-Strominger solution.

A model for multiple throat structures in the polar cap flow entry region

A two‐dimensional ionospheric convection model has been developed to produce convection patterns for southward interplanetary magnetic field (IMF) and a positive or negative IMF y component. The model consists of a movable, shear convection reversal boundary with a gap in it where flux enters the polar cap. The sign of IMF By determines the dayside gap geometry. We use this simple model to simulate measured ionospheric flows from the DE 2 satellite. Roughly 35% of DE 2 passes that cross the dayside between 0800 and 1400 hours MLT cannot be modeled with a single narrow flow entry region. By comparing model calculations and the measured ion flows, we show that the dayside flow entry region to the polar cap typically spans several hours in local time. The electric field can concentrate along portions of the polar cap entrance and weaken between the concentrated regions, thus forming multiple “throats.”

Tokamak pump limiters

Experiments with pump limiters on several operating tokamaks have established them as efficient collectors of particles. The gas pressure rise within the chamber behind the limiters has been as high as 50 mTorr when there is no internal chamber pumping. Observations of the plasma power distribution over the front face of these limiter modules yield estimates for the scale length of radial power decay consistent with predictions of relatively simple theory. Interaction of the in-flowing plasma with recycling neutral gas near the limiter deflector plate is predicted to become important when the effective ionization mean free path is comparable to or less than the neutral atom mean path length within the throat structure of the limiter.Recent experiments with a scoop limiter without active internal pumping have been carried out in the PDX tokamak with up to 6 MW of auxiliary neutral beam heating. Experiments have also been performed with a rotating head pump limiter in the PLT tokamak in conjunction with RF plasma heating. Extensive experiments have been done in the ISX-B tokamak and first experiments have been completed with the ALT-I limiter in TEXTOR. The pump limiter modules in these latter two machines have internal getter pumping. Experiments in ISX-B are with ohmic and auxiliary neutral beam heating. The results in ISX-B and TEXTOR show that active density control and particle removal is achieved with pump limiters. In ISX-B, the boundary layer (or scape-off layer) plasma partially screens the core plasma from gas injection. In both ISX-B and TEXTOR, the pressure internal to the module scales linearly with plasma density but in ISX-B, with neutral beam injection, a nonlinear increase is observed at the highest densities studied. Plasma plugging is the suspected cause. Results from PDX suggest that a regime may exist in which core plasma energy confinement improves using a pump limiter during neutral beam injection. Asymmetric radial profiles and an increased edge electron temperature are observed in discharges with improved confinement. The injection of small amounts of neon into ISX-B has more clearly shown an improved electron core energy confinement during neutral beam injection. While carried out with a regular limiter, this “Z-mode” of operation is ideal for use with pump limiters and should be a way to achieve energy confinement times similar to values for H-mode tokamak plasmas. The implication of all these results for the design of a reactor pump limiter is described.

SCARLATINA AND THE STREPTOCOCCUS INFECTION.

clinical history and symptomatology of scarlatina point to a virulent infection. Streptococci are found in the throat, cervical glands and other lymphoid structures, as well as in the blood, pleural, pericardial and peritoneal secretions, internal organs and skin of patients succumbing to this dread disease. Mr. Berge, in a paper read at a recent meeting of the Biological Society of Paris, maintains that scarlet fever is the result of a local infection by the streptococcus. In an article upon The Local Lesion of Scarlet Fever, Dowson speaks of the accidental inoculation of the tonsil by minute scratches while taking food. No one questions the common etiology of idiopathic and surgical scarlatina. Their relation to puerperal fever and pelvic suppuration is admitted. Consequently their affinity to any local abscess formation, septicemia or pyemia must be conceded. No clinician has failed to observe the likeness of the course and progress of