Cylindrical Neck Research Articles

Dual Helmholtz resonator

Acoustic characteristics of a dual Helmholtz resonator which consists of a pair of cylindrical neck and cavity connected in series (neck–cavity–neck–cavity) are established primarily in terms of a lumped-parameter theory. The results are then compared to (a) a two-dimensional analytical approach by applying a pressure/velocity matching technique for a piston-driven model; (b) a three-dimensional boundary element method for a pipe-mounted model; and (c) experiments on an impedance-tube test setup with one fabricated prototype installed in a sidebranch orientation (pipe-mounted model). Closed-form expressions have been developed in the present study for the resonance frequencies and the transmission loss of this two degree-of-freedom system based on the Newton’s second law of motion for a lumped system. The resonance frequencies and the transmission loss from this theory agree well with the analytical results, while showing a reasonable comparison with both the numerical predictions and the measurements.

Association of Microascus cirrosus (Microascaceae, Ascomycetes) with Brown Leaf Spot of Pistachio in Iran.

Iran is the largest pistachio-producing and exporting country in the world with an annual production of approximately 200,000 t. In July 2009, brown spots were noticed on the leaves of an unknown cultivar of pistachio (Pistacia vera L.) in the Mazhan Region of Birjand, South Khorasan, Iran. Nearly 20% of the trees in the surveyed area (1 ha) showed irregularly shaped leaf spots that were mainly on the abaxial surface, measured 4 to 6 mm in diameter, and were initially pale brown but progressively became dark brown. Lesions were cut from diseased tissues, surface sterilized, and placed on acidified potato dextrose agar (APDA). An anamorphic fungus was consistently isolated from the tissues. The fungus was identified as Microascus cirrosus Curzi (1,4). Colonies on PDA at 25°C reached 9 mm in diameter in 7 days and appeared olivaceous brown and zonate, and perithecia developed in 14 days. Perithecia were black, superficial or partially immersed, spherical, 110 to 200 μm in diameter, with cylindrical necks measuring up to 60 μm long by 25 to 35 μm broad; asci were globose to ovate, eight spored, and 9 to 11 × 8 to 10.5 μm; ascospores were pale reddish brown, variable in shape, ranging from concavo-convex, sometimes plano-convex to oval, and 4.5 to 6 × 3 to 4 μm. The associated anamorph on PDA was a Scopulariopsis sp. with annellophores borne singly or in groups of two or three, 10 to 16 × 2.5 to 3.5 μm, with abruptly narrowed apices; conidia were produced in chains, globose to subglobose, basally truncate, pale olive to fuscous, and 4 to 5 × 3 to 4 μm; chlamydospores were globose to pyriform, terminal or intercalary, and 8.5 to 17.5 μm in long axis. Pathogenicity of two isolates was tested using the filter-paper method of Takahashi et al. (3). Mycelial plugs (5 mm in diameter) as well as filter papers containing conidia were placed on five needle-wounded or nonwounded attached leaves of pistachio cv. Kale-Ghuchi in triplicate. The leaves were covered with a translucent plastic bag for 4 days. Inoculated detached and inoculated wounded attached leaves showed symptoms after 6 and 9 days on 5-month-old and 2-month-old leaves, respectively. Control leaves (five in triplicate) remained symptomless. The pathogen was frequently reisolated from the margins of the lesions. To our knowledge, this is the first record of M. cirrosus occurring on pistachio as well as the first report of a member of this genus from Iran. The same fungus has been reported as the causal agent of stored corn deterioration in the United States (1). M. cirrosus also produced a dimorphic yeast phase on PDA but not on malt extract agar or water agar. Cultures with partial reversion developed chlamydospore-like cells. Higher temperatures (25 to 30°C) and surface-sterilized pistachio leaves placed on PDA accelerated the reversion of the yeast phase to hyphal phase. Although dimorphism has been reported in other plant pathogenic fungi (2), this is the first report of dimorphism in this fungus and of a dimorphic fungus attacking pistachio. Further investigations are needed to determine the relation between dimorphism and pathogenicity. A culture (IRAN 1497 C) of the fungus is preserved by R. Zare.

MACROSCOPIC DYNAMICAL DESCRIPTION OF ROTATING Au + Au SYSTEM

Events with more than two heavy fragments have been abundantly observed in heavy-ion semi-peripheral (fission-like) reaction 197 Au +197 Au at 15 MeV/nucleon. This raised interesting questions about their origin and about the time-scale at which they occur. As a possible explanation of this process, the surface instability of the cylindrical neck that is formed along the path from contact to reseparation of the rotating Au + Au system is investigated in the present paper. For this purpose the Los Alamos finite-range macroscopic dynamical model was used. The calculations were performed at relatively high angular momenta, L = 100 to 300 ħ, for two types of dissipation mechanisms: two-body viscosity and one-body dissipation. Various initial nuclear deformations and initial kinetic energies in the fission direction were considered. The resulting dynamical evolution in the multidimensional deformation space always led to multifragment scission configurations suggesting that ternary and quaternary break-up can occur during the heavy-ion reaction studied.

The effect of hair on auditory localization cues

Previous empirical and analytical investigations into human sound localization have illustrated that the head-related transfer function (HRTF) and interaural cues are affected by the acoustic material properties of the head. This study utilizes a recent analytical treatment of the sphere scattering problem (which accounts for a hemispherically divided surface boundary) to investigate the contribution of hair to the auditory cues below 5 kHz. The hair is modeled using a locally reactive equivalent impedance parameter, and cue changes are discussed for several cases of measured hair impedance. The hair is shown to produce asymmetric perturbations to the HRTF and the interaural time and level differences. The changes in the azimuth plane are explicated via analytical examination of the surface pressure variations with source angle. Experimental HRTFs obtained using a sphere with and without a hemispherical covering of synthetic hair show a good agreement with analytical results. Additional experimental and analytical investigations illustrate that the relative contribution of the hair remains robust, regardless of the placement of the pinnas, or inclusion of a cylindrical neck.

SU-FF-T-140: Designing An Optimum IMRT Verification System

Purpose: A verification system must be integrated into the clinical environment for a quality-assurance measurement of each plan. As a Monte Carlo dose kernel is commercially available for IMRT planning, the development of a sophisticated IMRT verification system is absolutely necessary for inhomogeneity corrections which are not possible with a homogeneous phantom. Method and Materials: We designed a cylindrical head and neck phantom to verify the accuracy of the IMRT planning. The head and neck regions include the organs at risk (OARs) such as parotid glands, spinal cord, brainstem, and mandible which are often situated in the vicinity of the target. The cylinder dimension is similar to the human head and neck dimension. OARs and target are designed as slabs for easy insertion in the cylinder. Ionization chamber holders are inserted in OARs and target volume. This heterogeneous phantom was CT scanned, and the PMCEPT, an in-house Monte Carlo code, was applied to calculate the depth dose profiles for the phantom. Results: We manufactured materials similar to a typical patient's critical organs and target, and inserted them into the PMMA cylindrical phantom. For the Monte Carlo calculations, the measured CT numbers for each material were converted into mass densities and chemical compositions. Using the PMCEPT code, we computed dose distributions, and confirmed an electronic nonequilibrium at medium interfaces, in agreement with the measured PDD curves. Conclusion: We developed a heterogeneous phantom for routine IMRT dose verification. We evaluated optimum design parameters for the phantom using experiments and Monte Carlo simulations. We found that the PMCEPT code could accurately predict the dose in the heterogeneous phantom within 2 % error. Thus, our IMRT verification system is suitable for the sophisticated verification of routine individual patient IMRT plan, which will promote the quality of radiotherapy treatment. Supported by Com2Mac-MOST-KOSEF.

Ophiostoma arduennense sp. nov. ( Ophiostomatales, Ascomycota) from Fagus sylvatica in southern Belgium

Ophiostoma arduennense sp. nov. is described from several cultures isolated from Fagus sylvatica in southern Belgium. The species is mainly characterized by globose perithecia with small button-like bases ornamented with brown hyphal hairs of variable length and, long cylindrical necks ending in ostiolate hyphae. It is homothallic with small reniform ascospores and no apparent anamorph. It is closely associated with the ambrosia beetles Xyloterus domesticus and X. signatus. Its phylogenetic relationships within Ophiostoma are discussed and the species is compared with other Ophiostoma species associated with European beech or other broad-leaved trees in Europe, especially species of the O. quercus– O. piceae complex. The species is responsible for a dark brown staining of the sapwood and its role in the decline of beech in Southern Belgium is also discussed.

Assessment of the local SAR distortion by major anatomical structures in a cylindrical neck phantom

The objective of this work is to gain insight in the distortions on the local SAR distribution by various major anatomical structures in the neck. High resolution 3D FDTD calculations based on a variable grid are made for a semi-3D generic phantom based on average dimensions obtained from CT-derived human data and in which simplified structures representing trachea, cartilage, spine and spinal cord are inserted. In addition, phantoms with dimensions equal to maximum and minimum values within the CT-derived data are also studied. In all cases, the phantoms are exposed to a circular coherent array of eight dipoles within a water bolus and driven at 433 MHz. Comparisons of the SAR distributions due to individual structures or a combination of structures are made relative to a cylindrical phantom with muscle properties. The calculations predict a centrally located region of high SAR within all neck phantoms. This focal region, expressed as contours at either 50% or 75% of the peak SAR, changes from a circular cross-section in the case of the muscle phantom to a doughnut shaped region when the anatomical structures are present. The presence of the spine causes the greatest change in the SAR distribution, followed closely by the trachea. Global changes in the mean SAR relative to the uniform phantom are <11%, whilst local changes are as high as 2.7-fold. There is little difference in the focal dimensions between the average and smallest phantoms, but a decrease in the focal region is seen in the case of the largest phantom. This study presents a first step towards understanding of the complex influences of the various parameters on the SAR pattern which will facilitate the design of a site-specific head and neck hyperthermia applicator.

Annulusmagnus and Ascitendus, two new genera in the Annulatascaceae

Two pyrenomycetes in the Annulatascaceae described from freshwater, Annulatascus triseptatus and Ascolacicola austriaca, are reported from North and South America for the first time. Both species occur commonly on submerged wood in the U.S.A. The two taxa are similar morphologically in having black coriaceous ascomata, cylindrical necks, septate paraphyses, cylindrical pedicellate asci with prominent apical rings and three-septate ascospores. Molecular data demonstrates that Annulatascus is polyphyletic, with A. triseptatus on a clade widely separated from the type species of the genus, A. velatisporus. Ascolacicola austriaca is on a monophyletic clade within the Annulatascaceae as sister taxon of A. triseptatus. Based on morphological data and phylogenetic analyses of 28S rDNA sequence data, new genera Annulusmagnus and Ascitendus are established for Annulatascus triseptatus and Ascolacicola austriaca, respectively.

Drop pinch-off and filament dynamics of wormlike micellar fluids

Observations are presented of several novel phenomena involved in the dynamics of a pendant drop of viscoelastic micellar fluid falling through air. Generally, when a drop falls a filament forms connecting it to the orifice; the filament eventually breaks due to an instability. The filament dynamics and instabilities reported here are very different from the standard Newtonian and non-Newtonian cases. At low surfactant concentration, the cylindrical filament necks down and pinches off rapidly (∼10 ms) at one location along the filament. After pinch-off, the free filament ends retract and no satellite drops are produced. At higher concentrations, the pinch-off also occurs along the filament, but in a more gradual process (∼1 s). Furthermore, the free filament ends do not fully retract, instead retaining some of their deformation. The falling drop is also observed to slow or even stop (stall) before pinch-off, indicating that sufficient elastic stress has built up to balance its weight. We investigate this stall by generalizing Keiller’s simple model for filament motion [J. Non-Newtonian Fluid Mech. 42 (1992) 37], using instead the FENE-CR constitutive equation. Numerical simulations of this model indicate that stall occurs in the range of low solvent viscosity, high elasticity, and high molecular weight. At the highest concentrations, we observe a surface “blistering” instability along the filament long before pinch-off occurs.

Marmaris Müzesinden Üç Uzun Cam Unguentarium

Son yıllarda, Marmaris Müzesi tarafından, yerel bir satıcıdan üç adet uzun cam unguentarium satın alınmıştır. Bunların buluntu yeri bilinmemekle birlikte, çok benzer ölçülere, form ve cam özelliklerine sahip olmaları bakımından aynı mezar konteksti içinde, bir arada ele geçmiş olmaları gerekmektedir. Unguentarium, (özellikle tüp biçimli ve şamdan biçimli tipler) cam üflemeciliğinin yaklaşık olarak İ.Ö. 25 yılında icat edilmesinden sonra Roma camcılığında en yaygın görülen form haline gelmiştir. Roma günlük yaşamında sıkça kullanılan kokulu yağların, parfümlerin, merhemlerin yani, "unguent"lerin saklanmasına yaradığı için bu isimle tanınmaktadır.

Inverse planning for intensity-modulated arc therapy using direct aperture optimization

Intensity-modulated arc therapy (IMAT) is a radiation therapy delivery technique that combines gantry rotation with dynamic multi-leaf collimation (MLC). With IMAT, the benefits of rotational IMRT can be realized using a conventional linear accelerator and a conventional MLC. Thus far, the advantages of IMAT have gone largely unrealized due to the lack of robust automated planning tools capable of producing efficient IMAT treatment plans. This work describes an inverse treatment planning algorithm, called ‘direct aperture optimization’ (DAO) that can be used to generate inverse treatment plans for IMAT. In contrast to traditional inverse planning techniques where the relative weights of a series of pencil beams are optimized, DAO optimizes the leaf positions and weights of the apertures in the plan. This technique allows any delivery constraints to be enforced during the optimization, eliminating the need for a leaf-sequencing step. It is this feature that enables DAO to easily create inverse plans for IMAT. To illustrate the feasibility of DAO applied to IMAT, several cases are presented, including a cylindrical phantom, a head and neck patient and a prostate patient.

Monte Carlo Simulation Test of Pore Blocking Effects

We present a Monte Carlo (MC) simulation study of capillary condensation and desorption in a spherical cavity connected with the bulk phase by cylindrical necks of smaller diameter. We confirm two mechanisms of spontaneous evaporation from the cavity and, correspondingly, two types of adsorption hysteresis, which depend on the relation between the sizes of the cavity and the connecting pores. When the necks are sufficiently wide, evaporation from the cavity is determined by the conditions of evaporation from the neck. This is a classical ink-bottle or pore blocking effect: desorption from the cavity is controlled by the size of the neck. When the necks are narrow, evaporation from the cavity is determined by the conditions of cavitation in the stretched metastable liquid and thus does not depend on the size of blocking pores. MC simulations were performed for a Lennard-Jones fluid at the normal boiling temperature mimicking sorption of nitrogen at 77.4 K in silica mesopores. The simulation results agree with the density functional theory of capillary condensation hysteresis in spherical cavities and the experimental data reported recently (Ravikovitch, P. I.; Neimark, A. V. Langmuir 2002, 18, 1550 and 9830).

Inhibition of the finite-time singularity during droplet fission of a polymeric fluid.

When a drop of fluid detaches from a capillary, singular behavior ensues. We show that the addition of very small amounts of polymer inhibits this singularity in an abrupt way and gives rise, after a period of self-similar dynamics as for simple liquids, to long-lived cylindrical necks or filaments which thin exponentially in time. This abrupt change occurs when the elongation rate epsilon* becomes comparable to the inverse of the polymer relaxation time leading to a large elongational viscosity eta(E) of the dilute polymer solution.

Palatal implant anchorage reinforcement of posterior teeth: A prospective study

A new orthodontic implant anchor system (Orthosystem) has been developed. This 1-piece device made from titanium consists of a screw-type endosseous section (lengths of 4 and 6 mm), a cylindrical transmucosal neck, and an abutment. Clamp caps with slots provide for attachment of square orthodontic wires (transpalatal bars) to the implant. The aim of the present prospective study was to evaluate the anchorage capacity of palatally inserted Orthosystem implants for anchorage reinforcement of posterior teeth. The sample consisted of 9 dental Class II patients (age 15 to 35 years) whose treatment plan included extraction of the maxillary first premolars. Each of the patients received 1 implant inserted into the center of the anterior palate. After a mean unloaded implant healing period of 3 months, transpalatal bars were inserted to connect the posterior teeth to the implant. Retraction of the canines and incisors was accomplished without the use of compliance-dependent headgear or Class II elastics. The degree of anchorage loss as well as the amount of canine and incisor retraction were evaluated by measurements of the casts and lateral cephalograms. The mean anchorage loss was 0.7 mm on the right side and 1.1 mm on the left ( P < .05). The right and left canines were retracted 6.6 and 6.4 mm, respectively, and the mean overjet reduction was 6.2 mm. Because clinical assessment and postremoval histologic assessment both revealed stability of the short implant, the small anchorage loss was most likely from the deformation of the transpalatal bars by the orthodontic forces. Nevertheless, the treatment goal was achieved in all patients without the use of compliance-dependent auxiliaries. The clinical experience during and after implant insertion, active orthodontic treatment, retrieval of the implant, and subsequent wound healing are described. (Am J Orthod Dentofacial Orthop 1999;116:678-86)

Geometry of dendritic spines affects calcium dynamics in hippocampal neurons: theory and experiments.

The role of dendritic spine morphology in the regulation of the spatiotemporal distribution of free intracellular calcium concentration ([Ca2+]i) was examined in a unique axial-symmetrical model that focuses on spine-dendrite interactions, and the simulations of the model were compared with the behavior of real dendritic spines in cultured hippocampal neurons. A set of nonlinear differential equations describes the behavior of a spherical dendritic spine head, linked to a dendrite via a cylindrical spine neck. Mechanisms for handling of calcium (including internal stores, buffers, and efflux pathways) are placed in both the dendrites and spines. In response to a calcium surge, the magnitude and time course of the response in both the spine and the parent dendrite vary as a function of the length of the spine neck such that a short neck increases the magnitude of the response in the dendrite and speeds up the recovery in the spine head. The generality of the model, originally constructed for a case of release of calcium from stores, was tested in simulations of fast calcium influx through membrane channels and verified the impact of spine neck on calcium dynamics. Spatiotemporal distributions of [Ca2+]i, measured in individual dendritic spines of cultured hippocampal neurons injected with Calcium Green-1, were monitored with a confocal laser scanning microscope. Line scans of spines and dendrites at a <1-ms time resolution reveal simultaneous transient rises in [Ca2+]i in spines and their parent dendrites after application of caffeine or during spontaneous calcium transients associated with synaptic or action potential discharges. The magnitude of responses in the individual compartments, spine-dendrite disparity, and the temporal distribution of [Ca2+]i were different for spines with short and long necks, with the latter being more independent of the dendrite, in agreement with prediction of the model.

Breeding and nesting behaviour of d'orbigny‘s slider turtle Trachemys dorbignyi at Sao Paulo Zoo

From 1985 to 1994 the reproductive biology and nesting behaviour of d'orbigny's slider turtle Trachemys clorbignyi were studied at Sao Paulo Zoo. The mating season was from April to July and the egglaying season was from mid‐August to mid‐January. Nesting activity, which was similar to that reported for other species in the Chrysemys complex, was more frequent in the morning and could be divided into five distinct stages: nest‐site selection, nest excavation, egg laying, nest covering and return to water. Nests comprised a cylindrical neck and an oval incubation chamber, the dimensions of which were related to the type of substrate being excavated. Mean clutch size was 8.86 eggs (range = 1–18; n = 530 clutches). Eggs were ellipsoidal and were a mean 3.90 cm long, 2.54 cm wide and 14.07 g. Some ♀♀ laid at least two clutches in a season. The eggs were artificially incubated and mean incubation time was between 55.2 days at 31.5°C and 104.2 days at 25°C. Hatchlings had a mean carapace length of 3.55 cm, maximum carapace width of 3.34 cm and weight of 10.73 g.

The Description of Paralongicollum nemacheili n. gen., n. sp. (Acanthocephala: Pomphorhynchidae) from Freshwater Fishes in Kazakh S.S.R.

Paralongicollum nemacheili n. gen., n. sp. is described from Salmo gairdneri Richardson and Nemacheilus stoliczkai Steindacher in Lake Kul'say in the basin of Lake Balkhash, Kazakh S.S.R. Its long uniformly cylindrical neck and nonfiliform proboscis distinguish it from the other 3 genera of the family. Tenuiproboscis Yamaguti, 1935, has a filiform proboscis. The neck of Pomphorhynchus Monticelli, 1905, has a bulb anteriorly, and that of Longicollum Yamaguti, 1935, is spirally twisted with expansions. A key to the genera of Pomphorhynchidae is provided. The relatively longer necks in juveniles than in larger worms probably enhance the establishment of new infections. A large proportion of worms had extensive body wall deformities. Longicollum sergenti (Choquette and Gayot, 1952) Golvan, 1969, is relegated to the new genus Paralongicollum.

Mucobasispora, a new dematiaceous Hyphomycete genus from Egyptian soil

Mucobasispora, a new genus of the Hyphomycetes with M. tarikii sp. nov. is described and illustrated from cultivated soil in Egypt. Conidiogenous cells are flask-shaped with markedly swollen venters and long, narrow, cylindrical necks. Conidia are obovate, pigmented and develop retrogressively in long chains. Each conidium is ensheathed by a thick, sub-hyaline, mucoid membrane which collapses gradually giving rise to a reticulate conidial surface.

Discussion of Capabilities of Microwave Phased Arrays for Hyperthermia Treatment of Neck Tumors

The power deposition capabilities of phased arrays are investigated by means of numericaf modeling. Integral formulation and gradient conjugate techniques have been used to calculate the power deposited by complete or limited annular arrays in cylindrical neck cross sections. Comparisons with the power deposition patterns obtained by means of other heating modalities (RF capacitive electrodes, single microwave applicator or nonphased arrays) show that, even with a moderate number of elements, phased arrays are expected to provide better uniformity and larger penetration depths although improvements offered by phased arrays largely depend on the possibility to conveniently check the initial amplitude/phase adjustment of the array elements. Some existing and potential control procedures are addressed.

A Roman Glass Flask in Gaziantep Museum

Early Roman mould-blown glass vessels are widespread and well-known in the museums, private collections and sale rooms of Europe and America. However, one encounters such items less frequently in the regions where a great many of them were made. Although much work has been done on the origins and early practitioners of the craft of mould-blowing, few actual vessels have been recorded in the eastern Mediterranean and Middle East. So it is pleasing that I am able to add to the list a fine example in the Gaziantep Museum.Hexagonal flask. 1st century A.D. Translucent cobalt blue glass. Blown in a three-part mould. Flat bottom. Cylindrical neck with everted rim, lip folded inward. (Fig. 1 and Pl. XIX/a–c).Exact find-spot not recorded; acquired by purchase in the Gaziantep region. No registration number by October 1984.Height 7·8 cm. Diameter of bottom 2·4 cm.