Large Pole Research Articles

Rare earth magnets and impaction

Aberration in the eruption process was found to be a prime etiologic factor in inducing impaction. Thus an ideal treatment approach should attempt to mimic the normal eruption modus. However, conventional traction methods have been found to be associated with gingiva inflammation, bone recession, reduced attached gingiva, periodontal pockets, exposed cementoenamel junction, and root resorption of the impacted and adjacent teeth. These side effects are the result of premature exposure of the impacted tooth to the oral cavity through a nonself-cleansing pathway and an uncontrolled force system. The present study introduces a new, magnetic attraction system, with a magnetic bracket bonded to an impacted tooth and an intraoral magnet linked to a Hawley type retainer. Vertical and horizontal magnetic brackets were designed, with the magnetic axis magnetized parallel and perpendicular to the base of the bracket, respectively. The vertical type is used for impacted incisors and canines, and the horizontal magnetic bracket is applied for impacted premolars and molars. A three-dimensional analysis of the magnetic force system, by means of the OMSS apparatus, found the small magnetic bracket combined with a large pole surface area of the intraoral magnet to exhibit the most efficient convergent guidance. For this report the magnetic eruption device was examined on one animal subject and four patients. The Nd2Fe14B magnets were coated with parylene and/or encapsulated in stainless steel housings. In deep impaction, the magnetic bracket was cold-sterilized before surgery, and the surgical mucoperiosteal flap was then sutured over the bonded magnetic bracket. Attraction was initiated 1 to 2 weeks after healing. Thus tooth emergence into the oral cavity replicated normal eruption conditioning. The system operated at an attractive force level of 0.2 to 0.5 N. Adjustment was accomplished by temporarily interposing a magnetic spacer between the two magnetic units. No side effects were observed in this restricted number of treated cases, and treatment time was reduced. The study recommends the application of magnets in the treatment of impaction on the grounds of less invasive surgical procedure, effective attractive forces at short distances, and controlled spatial guidance.

Configurational dependence of the read-write properties of thin film heads

An experimental study to obtain the optimal configuration for a given frequency range is reported. Heads with pole lengths between 1.6 and 3.5 mu m, gap lengths of 0.5 and 0.3 mu m, 23 or 30 windings, and flying height of 0.2 mu m have been prepared. The heads have been tested on thin-film disks with coercivities, H/sub c/, of 650, 850, and 1100 Oe. The frequency response function and the form of the single pulses have been calculated. The spectral function of the reproduce voltage of a series of pulses with increasing frequency has been determined. The calculated single pulses and peak shift values show reasonable agreement between experiment and theory. Overwrite values show that disks with H/sub c/ up to 1100 Oe can be saturated by fields that can be achieved without significant saturation effects in the poles of the magnetic heads with pole lengths >2 mu m and 0.3- mu m gap length. The resolution increases with increasing pole length and increasing H/sub c/ of the disk. Larger pole lengths result in better peak shift values for densities higher than 12 KFCI. >

Novel parasitic insensitive SC large pole selectivity (Q) bandpass fitter with less capacitor spread and low pole ‘Q’ sensitivity

A new parasitic insensitive switched capacitor (SC) bandpass filter scheme is presented. The selectivity of the bandpass filter can be made very high without large capacitor spread, hence the proposed circuit consumes less chip area in monolithic integration and passive sensitivities of the circuit are found to be low.

Dynamics of the North Sea pole tide reconsidered

The anomalous tide in the North Sea, driven by the Chandler wobble, is here re-examined. A previously published solution in which these 'pole tide' observations were explained as a forced co-oscillation from the deep water tide is shown to be untenable, because it is very unlikely that the deep ocean tide is anything but equilibrium. Using the same physics as in the previous solution (viscous, linear, quasi-geostrophic dynamics), it is now suggested that the only plausible explanation is that there is a coincidental resonance between the long-wavelength branch topographic Rossby wave of the North Sea and the direct driving by the pole tide potential. This resonance is not a basin-resonance, but that of a free wave driven by a travelling forcing function. Simplified models reproduce the observations in qualitative fashion. If this explanation is the correct one, then the Arctic seas north of Asia and North America appear to be likely candidates as other regions where there may be a large pole tide response and, hence, a locus of wobble dissipation. Given the difficulties of observation, the long times required, and the general instability of the dissipation calculation with the simplified analytical model, probably a numerical model will be required for further progress.

4553122 Cored magnet with lightweight large area pole pieces

4553122 Cored magnet with lightweight large area pole pieces

Direct venous extension of renal cell carcinoma to common iliac vein with patent main renal vein

Direct spread of renal cell carcinoma to the renal vein and from there to the inferior vena cava (IVC) is a common occurrence. We present an unusual case of direct spread of a large lower pole tumor to the common iliac vein. New indications for studying the IVC and common iliac vein in renal cell carcinoma are suggested.

Reconstrution of a Presettlement Giant Sequoia‐Mixed Conifer Forest Community Using the Aggregation Approach

The presettlement state of a giant sequoia—mixed conifer forest community in the Redwood Creek watershed, Kings Canyon National Park, is reconstructed using in backward projection in time of plant aggregations. The most conspicuous change in the forest community from the presettlement condition (°1890) was a general increase in the area of aggregations dominated by polesize trees and mature trees, and a corresponding decrease in the area of aggregations dominated by sapling— and seedling—size trees. Aggregations dominated by white fir had both the greatest decline in area for sapling and seedling aggregations and the greatest increase in area for large mature, mature, and pole aggregations of any species in the watershed. The area of aggregations dominated by shrubs also declined, with manzanita aggregations showing the largest loss in area for any shrub species. Hardwoods were also a far more important part of the presettlement forest community than they are today.

Low-energy theorem for electron hyperfine interactions, and the special case of magnetic poles

The $S$-wave scattering length for a Dirac electron passing through a nonsingular magnetic field is shown to be given exactly by lowest-order perturbation theory. (Fermi contact term). In the presence of a pair of Dirac magnetic poles, the result is still correct in the limit of pole separation small compared to the electron Compton wavelength. In the limit of large pole separation, the scattering length takes the form appropriate to the case of a small magnet (whose internal structure is irrelevant) probing the field of the pole pair. In units of the magnetic dipole moment, the effect is half as big and opposite in sign to that in the small-separation limit. The passage from one limit to the other is qualitatively determined, and depends on boundary conditions at the poles. All of these statements depend on the neglect of electric fields, and of higher-order quantum-electrodynamics corrections like the anomalous magnetic moment of the electron.

Development and Cytology of Anixiella endodonta

The homothallic fungus Anixiella endodonta exhibits typical sordariaceous centrum development. The ascocarp begins development as a coiled or looped ascogonium that becomes surrounded by hyphal branches. The surrounding hyphae produce the ascocarp wall and all the nonascogenous elements of the centrum. A cavity forms within the centrum. Paraphyses grow upward into the cavity prior to ascus formation and disappear as the asci enlarge. Crozier formation, ascus production, and cytology within the ascus follow the typical pattern. A diffuse diplotene stage is included. Unusually large spindle pole bodies are striking elements of the interphase II nucleus. The haploid chromosome number is six. The development and cytology of A. endodonia is compared with that of previously studied species of Anixiella and Gelasinospora. Similarities and differences indicate that the two genera are clearly related but are sufficiently distinct to warrant segregation.

Versatile mass read-out system for magnetic sector mass spectrometers

A versatile digital mass read-out system for magnetic sector mass spectrometers is described. The system operates when the mass spectrometer is in the positive- or negative-ion mode and facilitates display of mass spectra on linear mass scales. It is suitable for use with instruments having large or small pole gaps and can be set up and calibrated quickly. With the mass spectrometer for which the system was initially designed reliable mass read-outs were obtained having a maximum error of +or-0.2 u up to a mass of 550 u.

Paleomagnetism of the Jacobsville Formation and the apparent polar path for the interval −1100 to −670 m.y. for North America

Chemical, thermal, and alternating field (af) treatments performed on 257 specimens (37 sites) of the Jacobsville Formation show that the magnetization was acquired gradually over a very long period of time. Three phases of magnetization can be recognized and sequentially separated chemically. Thermal (up to 675°C) and af (up to 290 mT) treatments are unable to distinguish and separate the first two phases. The results are consistent with a three‐phase magnetization model previously proposed and again demonstrate the necessity of performing chemical leaching experiments in red bed studies. The early phase remanence isolated chemically indicates that the Jacobsville is of upper Keweenawan age (≃− 1100 m.y.). Poles obtained from three areas, Sault Ste. Marie (SSM) (175°E, 12°N), Marquette (182°E, 03°S), and the Keweenaw Peninsula (KP) (184°E, 10°S), indicate that the sediments of SSM are older than those of KP. A detailed study (nine sites: mean pole at 190°E, 16°S) of a 5.3‐m stratigraphic section at Jacobsville shows significant apparent polar motion and the occurrence of at least one field reversal. The trend of the pole movement relative to North America was then southward. Vector analyses show that during the acquisition of the intermediate and late phase remanences the apparent pole started to move northward; by the end of the magnetization process it had reached high latitude (307°E, 72°N). Explanation of the Jacobsville results and other high‐latitude poles requires a major revision of the apparent polar path during the Hadrynian. The proposed path executes a loop into the southern hemisphere (−1100 to −950 m.y.) and then roughly follows a great circle path (Hadrynian Track) from 160°E near the equator up to the present north geographic pole and down to the equator at 340°E (−670 m.y.). The controversial Grenville poles could easily be incorporated into that loop, supporting the hypothesis that the Grenville Province has always been an integral part of Laurentia. The Hadrynian Track, with its large pole displacement (180° in 300 m.y.), is an extremely useful stratigraphic tool that can be used to great advantage for global correlations of late Precambrian rock units.

Pole cap formation in Escherichia coli following induction of the maltose-binding protein

After induction with maltose, 30--40% of the total protein in the osmotic shock fluid consist of maltose-binding protein while the induction ratio (maltose versus glycerol grown cells) for the amount of binding protein synthesized as well as for maltose transport is in the order of 10. Induction of maltose transport does not occur during all times of the cell cycle, but only shortly before cell division. Electronmicroscopic analysis of cells grown logarithmically on glycerol or maltose revealed in the latter the formation of large pole caps. These pole caps arise from an enlargement of the periplasmic space. Small cells contain one pole cap, large cells contain two. Pulse label studies with strain BUG-6, a mutant that is temperature sensitive for cell division reveal the following: Growth at the non-permissive temperature prevents maltose-binding protein synthesis and formation of new transport capacity. After shifting to the permissive temperature the cells regain both functions. Simultaneously, the newly formed cells exhibit pole caps. We conclude that the induction of maltose-binding protein is responsible for the formation of pole caps. In addition, beside the presence of inducer, cell cycle events occuring during division are necessary for the synthesis of maltose-binding protein.

Focussing for dipole magnets with large pole gap to bending radius ratios

The effect of pole face rotation on the axial focussing of dipole magnets is described for the case of small bending radius large pole gap magnets. An analytical expression is given which describes the focussing properties over the range of pole face rotation from −45° to +45°, and over the range of pole gap to bending radius ratio 0 to 0.5 and for the fringing field integral coefficient k from 0 to 0.4.

Survival and Mortality of Red Oak Borer Larvae1 on Black, Scarlet, and Northern Red Oak2 in Eastern Kentucky

Survival and mortality of 3 generations of the red oak borer, Enaphalodes rufulus (Haldeman), were studied over a 7-year period. The borers showed a preference for black oak over red and scarlet oaks. Larval mortality was about the same on all hosts. Tree vigor and size did not affect larval mortality; however, both factors did influence attack density. Potential brood trees are less than 29 cm dbh, small and large pole size, and are growing slower than 5.1 mm in diameter per year. Larval mortality was 40% in the early instars, primarily because of woodpecker predation. In the mid-instar stages, there was 51% mortality of the surviving larval population. This was due mainly to a sequence of events at the attack site: wound sap—insect invaders—fermenting medium. Lepidopterous wood borer larvae (largely Prionoxystus spp.) invaded wound sites when the red oak borer was in the mid- or late-larval stages and caused mortality by apparent direct killing of 5—10% of the surviving larvae.

Mariner 9 Science Experiments: Preliminary Results

On the basis of data provided by the IR interferometer spectrometer on the Mariner 9 spacecraft, it is suggested that the composition of the Martian dust corresponds approximately to that of rocks of intermediate silicon dioxide content. The large dynamical pole flattening obtained from satellite observations has been confirmed by the Mariner 9 data.

A Study of Pole Shapes for Quadrupole Magnets Having Circular Pole Tips

Harmonic field contents of quadrupole magnets having circular pole tips of various radii Rp's and rectangular coil slots at various distances Lcut's from the centre were numerically calculated by using two dimensional scalar potentials. Optimum radius of circular pole tip varies from 1.0088 to 1.1374 times the gap radius Rg as Lcut from 0.8 to 1.4 times Rg. Designs of optimum pole shapes for drift tube quadrupole magnets are discussed from harmonic field content, available coil space, core saturation and problems in fabrication. Flat poles as a limit of large pole tip radii were also calculated. A few measurements are compared with the calculations.

Episodes of sea-floor spreading recorded by the North Atlantic basement

A fresh compilation of available bathymetric, magnetic and seismic data in the central North Atlantic (west of the Mid-Atlantic Ridge) and north of the Azores (east of the Mid-Atlantic Ridge) reveals a complex episodic history of sea-floor spreading. JOIDES deep drilling results allow approximate dating of these episodes. By the end of the Jurassic, which was characterized by fast but decelerating spreading and few fracture zones, the central North Atlantic had reached about one third of its present width. Even before the end of this episode, close-spaced fracture zones and rough basement began to be formed, and this basement change appeared systematically later from north to south, consistent with the hypothesis that a threshold spreading rate was involved. As the spreading pole lay to the north, a decelerating spreading rate would necessarily bring a northern location through a given threshold rate before a southern one. Near the Jurassic-Cretaceous boundary, the Mid-Atlantic Ridge rapidly grew up to 0.5 km higher in some areas; this is known from basement topography and supported by a band of high-amplitude magnetic anomalies that suggest a thickened pillow lava layer about 50 km wide. This unusual band called the Bermuda Discontinuity, generally separates the rather densely fractured Cretaceous sea floor (about one fracture zone per 50–100 km) on the east flank of the Bermuda Rise from the Jurassic province to the west. Comparison of basement character with crustal structure suggests that, at least at the latitude of Bermuda, the “fast” Jurassic crust is “Pacific” (oceanic layer, normal mantle) whereas the Cretaceous sea floor is “Atlantic” (no oceanic layer, low velocity mantle). Sometime after the start of the Cretaceous, basement south of about 26° N again became “Pacific” (smooth, normal crust) whereas to the north it remained “Atlantic”. Cretaceous fractures yield a good azimuth to the virtual spreading pole, which is considerably southeast of the late Tertiary pole. The Cretaceous ended with the formation of basement elevations such as the Corner Rise. Major changes in spreading pattern probably occurred both at 76 and 60 m.y.B.P., the later date marking the separation of Greenland from Europe. Between about 60 and 40 m.y.B.P. fracture zones trend east-west or even WSW, suggesting the spreading pole moved west at the Cretaceous-Cenozoic boundary. After 40 m.y.B.P. large pole changes are not evident; a slight eastward movement may have occurred about 9 m.y.B.P. concomitant with the disappearance of numerous minor fracture zones. A preliminary comparison between spreading history on Reykjanes Ridge and deep drilling in Rockall-Hatton Basin suggests rapid subsidence following, by a few million years, each of three changes of spreading pattern. It is noteworthy that the three major events in the history of the North Atlantic all fall close to period boundaries, which therefore are not merely stratigraphic boundaries whose significance is restricted to Europe. Noting also the coincidence of the three major events with flood basalt episodes, we propose that discharge from mantle plumes, varying with crude 60 m.y. periodicity, has been the prime cause for the observed North Atlantic evolution.

Linear motors with transverse flux

The paper describes a new family of linear machines which may have advantage in applications where the pole pitch is very much greater than the machine width. Compared with the more usual kind of linear motor, in which the magnetic flux lies largely in planes which are parallel to the direction of motion, the new machines, have flux paths lying transversely to this direction. This shortens the magnetic circuit and reduces the weight of steel core needed in narrow machines of large pole pitch. Two experimental machines are described which illustrate the techniques needed in construction, and some initial calculations on possible weight gains are included.

Relationship between applied force, deformation of egg shells and fracture force

When an egg is compressed between flat parallel surfaces so that the compression surfaces contact the poles, the egg fractures most frequently at the large pole. However, the location of the moving surface may affect this frequency. In compression at the equator the moving surface has no effect. For machine design an eggshell can be considered as a Hookean element with a limited energy absorbing capacity. In predicting the force to fracture the shell, from a nondestructive compression test, greater accuracy is achieved as the force applied approaches the force at failure.

Ruptured Spleen

We attempted to clarify the details of incidental splenectomy complicating left nephrectomy.We reviewed the literature and operations involving splenectomy performed during left nephrectomy between 1984 and 1994 at our university. Factors reviewed included patient characteristics, renal pathology, mechanisms of injury, blood transfusions and postoperative complications.Of the 418 left nephrectomies 18 (4.3 percent) resulted in splenectomy via a transperitoneal approach. Patients with a large or upper pole renal lesion, malignancy or advanced age are increasingly likely to undergo unanticipated splenectomy.Our results, combined with recommendations from the Centers for Disease Control and Prevention, suggest that all patients older than 65 years undergoing left transperitoneal nephrectomy or those at increased risk for splenic injury should receive preoperative pneumococcal vaccination.