Permanent lunar surface magnetism and its deflection of the solar wind.

Magnetic compressions intermittently observed outside the lunar wake in the solar wind may be limb shocks caused by the presence of local regions of permanent magnetism on the lunar limb. Observable compression would be due to regions of length scale (radius) at least as great as several tens of kilometers and field strength greater, similar 10 gammas. Thousands of such regions might exist on the lunar surface. The steady magnetic field measured at the Apollo 12 site probably has length scale less, similar 10 kilometers and probably does not produce an observable limb shock.

Plasma observations near uranus: initial results from voyager 2.

Extensive measurements of low-energy positive ions and electrons in the vicinity of Uranus have revealed a fully developed magnetosphere. The magnetospheric plasma has a warm component with a temperature of 4 to 50 electron volts and a peak density of roughly 2 protons per cubic centimeter, and a hot component, with a temperature of a few kiloelectron volts and a peak density of roughly 0.1 proton per cubic centimeter. The warm component is observed both inside and outside of L = 5, whereas the hot component is excluded from the region inside of that L shell. Possible sources of the plasma in the magnetosphere are the extended hydrogen corona, the solar wind, and the ionosphere. The Uranian moons do not appear to be a significant plasma source. The boundary of the hot plasma component at L = 5 may be associated either with Miranda or with the inner limit of a deeply penetrating, solar wind-driven magnetospheric convection system. The Voyager 2 spacecraft repeatedly encountered the plasma sheet in the magnetotail at locations that are consistent with a geometric model for the plasma sheet similar to that at Earth.

Plasma observations near neptune: initial results from voyager 2.

The plasma science experiment on Voyager 2 made observations of the plasma environment in Neptune's magnetosphere and in the surrounding solar wind. Because of the large tilt of the magnetic dipole and fortuitous timing, Voyager entered Neptune's magnetosphere through the cusp region, the first cusp observations at an outer planet. Thus the transition from the magnetosheath to the magnetosphere observed by Voyager 2 was not sharp but rather appeared as a gradual decrease in plasma density and temperature. The maximum plasma density observed in the magnetosphere is inferred to be 1.4 per cubic centimeter (the exact value depends on the composition), the smallest observed by Voyager in any magnetosphere. The plasma has at least two components; light ions (mass, 1 to 5) and heavy ions (mass, 10 to 40), but more precise species identification is not yet available. Most of the plasma is concentrated in a plasma sheet or plasma torus and near closest approach to the planet. A likely source of the heavy ions is Triton's atmosphere or ionosphere, whereas the light ions probably escape from Neptune. The large tilt of Neptune's magnetic dipole produces a dynamic magnetosphere that changes configuration every 16 hours as the planet rotates.

Plasma observations near saturn: initial results from voyager 1.

Extensive measurements of low-energy plasma electrons and positive ions were made during the Voyager 1 encounter with Saturn and its satellites. The magnetospheric plasma contains light and heavy ions, probably hydrogen and nitrogen or oxygen; at radial distances between 15 and 7 Saturn-radii (Rs) on the inbound trajectory, the plasma appears to corotate with a velocity within 20 percent of that expected for rigid corotation. The general morphology of Saturn's magnetosphere is well represented by a plasma sheet that extends from at least 5 to 17 Rs, is symmetrical with respect to Saturn's equatorial plane and rotation axis, and appears to be well ordered by the magnetic shell parameter L (which represents the equatorial distance of a magnetic field line measured in units of Rs). Within this general configuration, two distinct structures can be identified: a central plasma sheet observed from L = 5 to L = 8 in which the density decreases rapidly away from the equatorial plane, and a more extended structure from L = 7 to beyond 18 Rs in which the density profile is nearly flat for a distance +/- 1.8 Rs off the plane and falls rapidly thereafter. The encounter with Titan took place inside the magnetosphere. The data show a clear signature characteristic of the interaction between a subsonic corotating magnetospheric plasma and the atmospheric or ionospheric exosphere of Titan. Titan appears to be a significant source of ions for the outer magnetosphere. The locations of bow shock crossings observed inbound and outbound indicate that the shape of the Saturnian magnetosphere is similar to that of Earth and that the position of the stagnation point scales approximately as the inverse one-sixth power of the ram pressure.

Plasma observations near saturn: initial results from voyager 2.

Results of measurements of plasma electrons and poitive ions made during the Voyager 2 encounter with Saturn have been combined with measurements from Voyager 1 and Pioneer 11 to define more clearly the configuration of plasma in the Saturnian magnetosphere. The general morphology is well represented by four regions: (i) the shocked solar wind plasma in the magnetosheath, observed between about 30 and 22 Saturn radii (RS) near the noon meridian; (ii) a variable density region between approximately 17 RS and the magnetopause; (iii) an extended thick plasma sheet between approximately 17 and approximately 7 RS symmetrical with respect to Saturn's equatorial plane and rotation axis; and (iv) an inner plasma torus that probably originates from local sources and extends inward from L approximately 7 to less than L approximately 2.7 (L is the magnetic shell parameter). In general, the heavy ions, probably O(+), are more closely confined to the equatorial plane than H(+), so that the ratio of heavy to light ions varies along the trajectory according to the distance of the spacecraft from the equatorial plane. The general configuration of the plasma sheet at Saturn found by Voyager 1 is confirmed, with some notable differences and additions. The "extended plasma sheet," observed between L approximately 7 and L approximately 15 by Voyager 1 is considerably thicker as observed by Voyager 2. Inward of L approximately 4, the plasma sheet collapses to a thin region about the equatorial plane. At the ring plane crossing, L approximately 2.7, the observations are consistent with a density of O(+) of approximately 100 per cubic centimeter, with a temperature of approximately 10 electron volts. The location of the bow shock and magnetopause crossings were consistent with those previously observed. The entire magnetosphere was larger during the outbound passage of Voyager 2 than had been previously observed; however, a magnetosphere of this size or larger is expected approximately 3 percent of the time.

Vertigo in children: differential diagnosis and treatment.

A study of vertigo in 50 children showed that a careful neurological examination should be performed for all patients. A detailed family and personal history to find possible episodes of loss of consciousness or seizures should be obtained; 13 children with vertiginous seizures had a positive family history for seizures and 5 had febrile seizures in infancy. Electroencephalograms should be obtained in all instances of vertigo occurrence.

Tragal perichondrium and cartilage in reconstructive ear surgery.

Two hundred and fifty-five ear operations using tragal perichondrium and cartilage for reconstruction are presented. Of these, 108 were myringoplasties, 137 were tympanoplasties with ossicular reconstruction performed by nine different methods, and 10 were tympanoplasties with reconstruction of posterior canal wall defects left by radical mastoid surgery. The method presented in this study of using the tragal perichondrial graft is well suited for myringoplasty and can be used where the drum remnant is very small or the anulus is missing. The natural angle of the tragal perichondrium can take the place of the missing anulus anteriorly, inferiorly or posteriorly. Myringoplasty graft survival at one year follow-up was 92%, and 76% had hearing within 10 db of bone conduction. In tympanoplasty, the tragal perichondrium was used en bloc with its cartilage for reconstruction of the ossicular chain where suited. The malleus was used to reconstruct the ossicular chain in different variations. Other methods used are fully described. At one year follow-up the rate of grafting success for tympanoplasties was 91%, and 78% had hearing within 10 db of bone conduction. A method for reconstruction of the posterior canal wall and tympanoplasty after radical mastoidectomy is presented. It uses tragal cartilage and perichondrium en bloc. At one year follow-up, eight of ten cases operated on by this method had an intact drum and posterior canal wall, one had an intact drum but the posterior canal collapsed into the mastoid, and one had an intact canal wall but the eardrum re-perforated. Nine had postoperative hearing within 10 db of bone conduction. A randomly selected group of 100 tympanoplasties was examined for postoperative gain in hearing according to the speech reception threshold, a more practical criterion of surgical success than 10 db air-bone gap. Although the total number showing improvement was similar to the number gaining hearing within 10 db of pure tone bone conduction (76% vs. 78%), when changes of 5 db were discounted, only 56% were improved (and 33% had a significant gain in hearing).

The normal nystagmic response of infants to caloric and perrotatory stimulation.

Infants (276) were tested with perrotatory and caloric vestibular stimulation at 3-month intervals, from birth till 12 months of age and at 6-month intervals from 12 to 24 months. They were grouped by gestational age and weight at birth. Statistical analyses of the various features of the nystagmus obtained at different ages were performed. Premature and low weight infants were found to have the longest latency and smallest frequency, amplitude and speed of slow component during the first 6 months. As they matured, the latency of response became shorter while the other parameters increased. Complete maturation of responses was attained in all infants within 6 to 12 months of age. Standards for normal vestibular responses in infants up to 24 months of age are set in this study.

Post-traumatic facial nerve paralysis: three cases of delayed temporal bone exploration with recovery.

No consensus exists today on the management of immediate-onset post-traumatic facial nerve paralysis. Controversy surrounds the timing of surgical intervention and the role of electrophysiologic testing. Three patients are presented who sustained immediate, complete facial paralysis following closed head trauma. They did not have prompt facial nerve decompression. In each case, electroneurography and electromyography showed complete nerve degeneration and denervated muscle. Despite the results of the electrophysiologic tests, all patients underwent late surgical decompression of the nerve: one at 2 1/2 months, one at 3 months, and one as late as 14 months after injury. They all had good recovery of facial function within 6 months of surgery. Early surgical intervention has been advocated in post-traumatic facial nerve paralysis if any benefit is to be gained. It is thought that late surgical intervention is unlikely to yield further improvement in the facial nerve function. Experience with these cases suggests that surgical exploration of the facial nerve is indicated at anytime, as it may be beneficial even in very old injuries. The prognostic value of electroneurography and electromyography in determining facial nerve recovery and in deciding upon facial nerve surgery is questioned.

Repair of nasal septal perforations with tragal cartilage and perichondrium grafts.

Indications for repair of nasal septum perforations include excessive crusting, recurrent bleeding, whistling, and pain. Large subtotal perforations usually are less symptomatic, but smaller defects (less than 1 cm) may need repair. Tragal cartilage with perichondrium autograft was used to repair these perforations. After the septal defect was debrided, this free graft was harvested and used to fill the defect. This technique was attempted in ten patients with septal perforations, none secondary to systemic illnesses. Nine of these patients had successful closure of their perforations.

Aminoglycoside ototoxicity in the neonatal period: possible etiologic factor delayed postural control.

Forty-three infants, treated with aminoglycosides during the neonatal period, were tested repeatedly over a period of two to five years for neurovestibular responses. Results of testing were compared with those obtained from a group of 276 healthy newborns followed simultaneously. No abnormalities were found in the untreated group. Among the treated infants, three had a sensorineural hearing loss and eight had laboratory evidence of vestibular dysfunction and delay of head and postural control.