Special Ring Research Articles

Laparoscopic appendicectomy using endo-ring applicator and fallope rings.

Background/Aim:Wider adoption of laparoscopic appendicectomy (LA) is limited by problems in securing the appendiceal base as well as the cost and the duration compared with the open procedure. The objective of this study was to assess the feasibility and efficacy of a new method for securing the appendiceal base in LA, so as to make the entire procedure simpler and cheaper, and hence, more popular.Methods:Twenty-five patients who were candidates for appendicectomy (emergency as well as elective) and willing for the laparoscopic procedure were selected for this study. Ports used were 10 mm at the umbilicus, 5 mm at the lower right iliac fossa, and 10 mm at the left iliac fossa. Extremely friable, ruptured, or turgid organs of diameters larger than 8 mm were excluded from the study. The mesoappendix was divided close to the appendix by diathermy. Fallope rings were applied to the appendiceal base using a special ring applicator, and the appendix was divided and extracted through the lumen of the applicator.Results:The procedure was successful in 23 (92%) cases, and the mean duration of the procedure was 20 minutes (15–32 minutes). There were no procedural complications seen during a median follow-up of two weeks. The equipment and rings were cheaper when compared with that of the standard methods of securing the base of the appendix.Conclusion:LA using fallope rings is a safe, simple, easy-to-learn, and economically viable method.

Thermophysical processes in vacuum plasma electric furnaces for heating powdered materials

Vacuum hollow-cathode plasmatrons permit heating, melting, and refining of fine powders in plasma during the flight of particles from the introduction zone to a receiver. A powder in plasma is heated through its interaction with electrons and ions. Such a plasmatron exhibits the following performance characteristics: the total heat flow per particle is 10 6 ‐10 7 W/m 2 , the operation pressure range is 0.1‐100 Pa, the current is 7.5‐10 kA, the voltage is 80‐100 V, and the working gas is argon. As a result of the electrodynamic interaction of every powder particle with the magnetic field of the plasma column, the powder concentrates at the plasma-column axis and moves only within the plasma column. All of the charged powder is treated. The initial content of impurities in the powder can reach 3% [1]. As the probe measurements of the column structure established, the plasma density decreases when going from the cathode cut toward the anode [2]. In this case, the plasma density is maximal in the active zone in the cathode hollow. To intensify the heat flow to a powder particle, we developed a special ring cathode, in which the inner cylinder is shorter than the external cylinder by (0.5‐1) the inner cylinder diameter. The external cylinder has a diaphragm and serves as a guard ring, and it prevents the plasma from sharp decomposition. As a result, the zone of the interaction of the powder with the dense plasma increases. Figure 1 presents a photograph of the ring hollow cathode providing effective heating of powder materials in a plasma column. The new cathode unit design allowed us to increase the temperature of the treated powdered material to 3500 ° C. When producing a compacted tantalum ingot from a powder of sodium-thermic reduction in a commercial plant, we achieved a decrease in the metallicimpurity content by a factor of 10‐40 and in the gaseousimpurity content by a factor of 5‐50. The quality of the ingots fabricated using the vacuum plasmatron is significantly higher than that of similar ingots produced in vacuum arc furnaces and is close to the quality of the metal produced by electron-beam remelting [1].

A ring area formed around the erosion pit on 1Cr18Ni9Ti stainless steel surface in incipient cavitation erosion

After a 1 min cavitation experiment performed in an ultrasonic vibration system, needle-like erosion pits appeared on a polished stainless steel surface, and a special ring area was formed around each pit. The shape of the pit and the plastic deformation of the ring area indicate that the mechanical impaction on the surface is the main reason for the cavitation erosion. On the other hand, the iridescent color, the decreased surface hardness and the appearance of the precipitated carbon ring prove that the ring area has experienced a tempering process with the temperature higher than 300 °C. Also, the lack of oxygen in the ring area proves that it is not a chemical oxygen result.

A preliminary pharmacophylogenetic investigation in Schisandraceae

The family Schisandraceae (Magnoliiadae) contains approximately sixty species which are disjunctly distributed in the southeast of Asia and North America. It was divided into two genera, Schisandra and Kadsura, represented by 29 species in China, 19 in Schisandra and 10 in Kadsura. This paper reviews current knowledge about the chemistry, ethnopharmacology and pharmacology of the family in an attempt to present a preliminary study into the pharmacophylogenetics of the family as a whole. Dibenzocyclooctadiene lignans (I) are considered to be the main chemical components of the family. Despite their traditionally recognized hepatoprotective function, they also exhibit anti-oxidant, anti-cancer and anti-HIV potential. Those dibenzocyclooctadiene lignans (I) possessing hydroxyl or angeloyloxy groups at C-6 or C-9 in the ethylidene-cyclooctane ring tend to exhibit a higher anti-cancer activity. Spirobenzofuranoid dibenzocyclooctadienes (II), mostly present in Kadsura, contain a special tetrahydrofuran ring spanning the biphenyl linkage and these demonstrate particular anti-PAF activities. This supports the traditional use of Kadsura to improve blood circulation and "remove dampness". Spirobenzofuranoid dibenzocyclooctadienes (II) could be considered as the bioactive marker compounds in Kadsura and hence markers for assessing quality. The distribution of all known lignans in the family showed that Kadsura is relatively advanced in evolution. Cycloartanone triterpenes occur in both Schisandra and Kadsura. Those with the A-ring open (II) tend to exhibit greater anti-cancer and anti-HIV activity. 7/7/5/6 triterpene lactones (IV), showing strong cytotoxicity, have only recently been discovered in Kadsura longipedunculata and as such have potential as anticancer agents. Recently, novel nortriterpenoids possessing a unique skeleton were found in S. lancifolia and S. micrantha; some exhibited clear anti-cancer or anti-HIV activity and are the subject of separate studies.

Detection and characterization of the disturbed rock zone in claystone with the complex resistivity method

Underground excavations provoke in their vicinity a region, where the rock is disturbed, i.e., loosened due to micro as well as macro fractures. Shape, dimension and properties of this so-called ‘excavation damaged zone (EDZ)’ are of increasing importance for the planning and construction of geotechnical barriers in underground repositories for toxic and problematic wastes. One way of assessing the EDZ around a drift is the investigation of the geoelectrical complex resistivity. In addition to resistivity, the phase measurements yield information about the pore spaces and not only about the water content. Measurements of resistivity and phase are conducted in a newly built tunnel in the opalinus claystone of the Mont Terri underground rock laboratory. Special ring profiles, as well as a geometry-adapted inversion scheme, are used. Significant local and temporal changes are found in the resistivity as well in the phase, which are directly associated with the disturbed rock zone. Laboratory measurements allow the correlation and quantification of resistivity and water saturation of the rock. A geotechnical modelling and an analysis of the stress pattern around the drift show that the geoelectrical properties agree remarkable with the mechanical state of the rock.

SONET/SDH ring assignment with capacity constraints

We consider the problem of interconnecting a set of customer sites using bidirectional SONET rings of equal capacity. Each site is assigned to exactly one ring and a special ring, called the federal ring, interconnects the other rings together. The objective is to minimize the total cost of the network subject to a ring capacity limit where the capacity of a ring is determined by the total bandwidth required between sites assigned to the same ring plus the total bandwidth request between these sites and sites assigned to other rings. We present exact, integer-programming based solution techniques and fast heuristic algorithms for this problem. We compare the results from applying the heuristic algorithms with those produced by the exact methods for real-world as well as randomly generated problem instances. We show that two of the heuristics find solutions that cost at most twice that of an optimal solution. Empirical evidence indicates that in practice the algorithms perform much better than their theoretical bound and often find optimal solutions.

On the expected number of generators of a submodule of a free module over a finite special principal ideal ring

On the expected number of generators of a submodule of a free module over a finite special principal ideal ring

Systems on intuitionistic fuzzy special sets and intuitionistic fuzzy special measures

In this study, we introduce some systems of subsets of intuitionistic fuzzy special sets (IFSS); namely, intuitionistic fuzzy special σ-algebra (IFSσ-A), intuitionistic fuzzy special algebra, intuitionistic fuzzy special ring and intuitionistic fuzzy special Dynkin system. We also introduce the concepts of intuitionistic fuzzy special measurability of IFSS, intuitionistic fuzzy special measures and intuitionistic fuzzy special measurable functions. Finally, consequences of these concepts and some basic results are given.

Conductance oscillations through an aharonov-bohm ring with a quantum gate

Based on a one-dimensional quantum wave guide theory, we investigate the ballistic conductance through an Aharonov-Bohm ring with a quantum gate. The analytical expression of the conductance is exactly obtained as the function of magnetic flux penetrating the ring and Fermi energy of indcident electrons. When Fermi energy equals that of bound states in the isolated stub, the conductance is fixed at a constant value which is only determined by the geometric structure of the ring system. We have found that there are a new kind of conductance oscillations for some special mesoscopic ring systems. As Fermi energy of incident electrons crosses that of bound state in the isolated stub, the conductance oscillations have no abrupt change of phase by π and are in phase. This striking feature is not in ageement with that of previous experiments and theories. The mechanism causing this new feature is discussed.

Three electrodes touch-mode capacitive pressure sensor

A three-electrode capacitive pressure sensor for touch-mode operation with sensitivity of 0.030 pF/kPa (or 10.4 mV/kPa using CP-10 C/V converter circuit) in the pressure range of 170–280 kPa is presented with theoretical explanation of experimental results. A special ring structure is designed to integrate a sensing capacitor and a reference capacitor into the same cavity to partially cancel out the temperature effect. A third electrode is included to eliminate two-level connections without reducing its pressure sensitivity. The sensor offers the advantages of simple fabrication processes, planar connections, as well as high sensitivity, near-linear output, and large over-range pressure.

High throughput VLSI DSP using replicated finite rings

This paper discusses strategies for implementing DSP systems using residue replication. The theory, recently introduced by two of the authors, uses formal polynomial ring mappings, from binary representations, to direct product ring implementation of integer processing arrays. The mapping produces completely independent computational arrays each computing over the same ring. This paper describes an architecture and processing array to implement, and take advantage of, the special computational ring structures that result from the mapping. A brief review of the theory and mapping techniques, is followed by the discussion of the architecture and VLSI design of an efficient inner product processing array using Fermat Primes.

Irradiation tests of double-sided silicon strip detectors with a special guard ring structure

The results of the first irradiation tests of newly designed silicon microstrip detectors performed with 21 MeV protons at the Max-Planck-Institut in Heidelberg are presented. The detectors were developed and produced by the semiconductor laboratory of the Max-Planck-Institut in Munich. Novel guard ring structures allow operation of the detectors at voltages exceeding 300 V.

High-efficiency, high-density MHz magnetic components for low profile converters

A highly efficient (99.5%) transformer and resonant inductor with very high power density (1500 W/in/sup 3/) and low profile (height <0.4 in) are described. These may be the highest numbers for power density for 99.5% efficient magnetic components. The design of these components is based on a trade-off study which establishes the optimum operating frequency to be around 1 MHz. The results of this trade-off study which established the baseline designs including the sizes are described. The transformer utilizes highly efficient thin flex circuit windings. The windings are novel folded copper patterns which eliminate the need for vias and results in very low DC resistance. The windings' arrangements have a high degree of interleaving between the primary and the secondary windings, resulting in very low AC conductor losses due to skin and proximity effect. The core is a low profile design with very low core losses. The resonant inductor, instead of using low permeability material, uses highly efficient high permeability material. The desired low permeability is then achieved by putting a large number (>40) of small gaps to reduce the effect of fringing fields. The high-frequency loss measurements for such highly efficient inductors requires a special ring down measurement set-up which is also described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Characterization of sulfobetaine monomers by nuclear magnetic resonance spectroscopy: a note

A set of zwitterionic monomers bearing the 3-ammoniopropanesulfonate moiety is analysed in CDCl 3, CD 3OD and D 2O by one- and two-dimensional 1H n.m.r. and 13C n.m.r. spectroscopy. Absolute and relative positions of the n.m.r. signals are determined depending on the solvent used; the refined assignments of the signals in the vicinity of the ammonium group deviate from previously proposed assignments based on standard n.m.r. shift tables. Still, there is no convincing evidence for a special ring current effect due to a six-membered ring conformation of the betaine moiety.

Analysis of residual stresses and cracking of γ-TiAl castings

A coupled thermo-mechanical model has been developed to calculate the residual stresses upon cooling, the resulting distortions and cracking sensitivity as a function of the casting conditions. The developed programmed module was used to carry out investigations on thermal stresses and cracking behaviour of γ-TiAl investment castings. Special ring geometries with various casting moduli were chosen for the determination of the cracking sensitivity of TiAl castings. A criterion function that describes the cracking sensitivity has been derived from the temperature and stress history. The calculated results were compared to the real TiAl castings.

A new approach to in situ left ventricular volume clamping in dogs

Major contributing factors modulating left ventricular (LV) diastolic behavior are active relaxation of myocardium and volume change during filling, the interaction of which complicates analysis of diastolic pressure-volume relationship, especially in early diastole. To separate the effect of active relaxation and filling, a method was introduced [E. L. Yellin, M. Hori, C. Yoran, E. H. Sonnenblick, S. Gabbay, R. W. M. Frater, Am. J. Physiol. 250 (Heart Circ. Physiol. 19): H620-H629, 1986] to interrupt mitral inflow and keep LV volume constant throughout diastole. Their preparation requires replacing the mitral valve with an artificial valve using cardiopulmonary bypass, which might cause significant change in cardiac performance or produce detrimental systemic effects. We developed a new volume-clamping method that preserves the native mitral valve and apparatus intact and avoids cardiopulmonary bypass. A modified Bjork-Shiley prosthetic valve (20 mm orifice diam) in a special mounting ring was placed above the native mitral valve through the left atrium and secured from outside the heart. This prosthetic valve was controlled by a cable connected to solenoids outside the dog, triggered by the electrocardiogram or other physiological signal. We compared our method (n = 7) with that of Yellin et al. (n = 2) in nine random source dogs. In our method, no end-diastolic pressure gradient or regurgitant pressure wave was observed, and the prosthetic valve did not disturb movement of the native mitral valve. When the prosthetic valve was forced to a closed position at end systole, LV volume, measured with a conductance catheter, was maintained at or near end-systolic volume throughout diastole.(ABSTRACT TRUNCATED AT 250 WORDS)

Special Principal Ideal Rings and Absolute Subretracts

AbstractA ringRis said to be an absolute subretract if for any ringSin the variety generated byRand for any ring monomorphismffromRintoS, there exists a ring morphismgfromStoRsuch that gf is the identity mapping. This concept, introduced by Gardner and Stewart, is a ring theoretic version of an injective notion in certain varieties investigated by Davey and Kovacs.Also recall that a special principal ideal ring is a local principal ring with nonzero nilpotent maximal ideal. In this paper (finite) special principal ideal rings that are absolute subretracts are studied.

The calculation of the stress intensity factor KI for a special open ring compact tension specimen

The calculation of the stress intensity factor KI for a special open ring compact tension specimen

Charge measurement of dust particles in motion

The charging of dusts or powders formed in a discontinuous flux in air is measured with a novel non-contactive method. A special ring probe was designed to measure the resultant electric charge of dust particles passing through the probe without disturbing the flow. The scope of the investigations was to verify the method proposed and to examine the influence of mass, equilibrium moisture content and velocity of motion on the electrification of PVC dusts. Experiments were carried out to study the generation of charge in the initial stage of flux formation. A mathematical model was derived to describe the response of the measuring system to the flowing resultant charge and its velocity. After the measuring system had been calibrated the empirical equation was obtained. The resultant charge (qr) and the initial rate of charge accumulation in the flux are found to be strongly dependent on the velocity of the air carrier, which causes that the dust particles are torn off from the metal surface of the feeder. The validity of the adopted measuring procedure is proved by experiments. The results obtained in terms of the mathematical model are consistent with the experimental data.

Central polynomials for special Jordan rings without nilpotent elements, and an analog of Kaplansky's theorem

In [7], a theory of nonassociative algebras with central polynomial was given, with several applications to Jordan algebras. The main theorem of this paper is that every special Jordan PI-ring J without nilpotent elements satisfies a class of central polynomials (related to the Formanek-Amitsur class of central polynomials for associative rings). This yields a “generic” Hamilton-Cayley equation for J. I f J is a torsion-free module over its center, then we can apply a result of Shirshov [9] (cf. [IS]) to [8], t o see that the “ring of central quotients” of J is simple and is either the Jordan algebra of a symmetric bilinear form or is finite dimensional (over its center), with a bound on the dimension computed in terms of the PI degree. In particular, every special Jordan PI-division ring is finite dimensional. This generalizes part of a result of Smith [ll], that every special algebraic simple Jordan PI-ring is finite dimensional. After this paper was distributed in preprint form, Bokut [17] announced the determination by Zelmanov of all Jordan division algebras of characteristic f2, thereby completing the Jacobson-Osborn structure theory of Jordan algebras with $ satisfying the descending chain condition on inner ideals; a generalization of Theorem 7 would follow immediately from Zelmanov’s results. To prove the main theorem we obtain a criterion for an element a of a special Jordan algebra without nilpotent elements to be central, namely, that [a, a, x] = 0 for all elements x. ([a, b, c] denotes the associator (ab)c a(&).) This is proved by verifying a fact about generalized identities of associative rings with involution. Other notational conventions are: [a, b] denotes ub bu, Z(R) denotes the center (of a ring R) = (a E R 1 [z, R, R] = [R, z, R] = [R, R, z] = [R, z] = 0). Nil ( ) denotes “the” maximal ideal of nilpotent elements, where an element Y is nilpotent if we can take some product of r, under suitable placement of paren-