A technique to estimate the body volume of newborns has been developed using the principle of the Helmholtz resonator. The change in the resonance frequency of a small cavity after an infant is placed inside can be used to determine the body volume of the infant. A prototype system, termed an acoustic plethysmograph, was built and used to measure the volume of newborn miniature pigs. Results of the animal body volume measurements compare favorably (within an average of 1.1%) with body volumes measured by hydrostatic weighing.

This paper describes the first phases of development of a drilling system for offshore wells based on the use of lightweight solid additives (LWSA) to reduce the density of drilling fluid within the riser above the seafloor. Equipment and procedures were tested to pump LWSA down to the bottom of the riser without damage, separate them from the mud after the fluid mixture returns to the surface, recycle LWSA for immediate re-use, as well as several other problems. Initial developments and tests are described that successfully addresses many of these issues. In offshore wells, particularly in deep water, the problem of maintaining a safe range of mud weights is compounded by the additional pressure that drilling mud in the riser exerts on the formation. If the effective weight of mud in the riser can be reduced, the range of safe mud weights is effectively widened at the formation, resulting in fewer casing strings and safer operations. Mud with high concentrations of LWSA might be pumped down from the surface through special lines and then injected into the riser at the mud line. The mixture of mud and LWSA flowing up the riser then weighs less than pure mud. LWSA were developed and tested as spheres produced from different materials including glass, composites, and epoxy resins. Tests showed that LWSA could withstand high pressures existing at the bottom of risers. LWSA were able to be separated from oilfield muds using conventional oilfield shale shakers and hydrocyclones. Muds with LWSA could be pumped with conventional mud pumps without excessive pressure losses. LWSA were recirculated many times with minimal breakage, demonstrating that they could survive in commercial operations. Significant cost savings will be possible in drilling offshore wells if remaining problems with LWSA can be addressed. In addition to reducing the number of casing strings required, drilling with LWSA would reduce tension load requirements on the riser and mud storage requirements on the drilling vessel, which will reduce the size of drillships or increase depth capability of existing vessels. Introduction Deep Water Drilling Problems. Problems are often encountered in deepwater wells with lost circulation and fluid influx. These issues increase costs and make deepwater drilling uneconomical in many areas. One major concern that exacerbates these fluid problems is maintaining wellbore annulus pressure above pore pressure so that the well does not "kick", and below fracture pressure so that the well does not hydraulically fracture and lose circulation. In deep water, pore and fracture pressure gradients are typically close together, making drilling very difficult. Figure 1 shows mud hydrostatic pressure gradients for offshore drilling. Because of the seawater column, and the unconsolidated nature of sediments near the seafloor, the pore pressure (A) and fracture pressure (B) curves are often close together, making it difficult to maintain wellbore annulus pressure between these curves.

An acoustic plethysmograph intended to measure the body volume of premature infants has been developed using the principle of the Helmholtz resonator, in which the resonance frequency is dependent on the volume of the resonating cavity. A prototype system was built and used to measure the volume of inanimate objects and newborn miniature pigs. Results for inanimate objects agree within 1 percent with comparable measurements by water displacement. Results of the animal body volume measurements compare favorably (within an average of 1.1 percent) with those obtained using hydrostatic weighing.

No abstract

c r e t e d (~l / u m o l ) , was g r e a t e r (p<.01) i n t h e two youngest groups.10-14 d (80) and 17-22 d (70) compared t o t h e a d u l t (50) and 25-30 d (44) rabb i t s . T h e ch1oride:bile s a l t r a t i o was a l s o higher i n t h e two youngest groups.Bile salt-independent flow a t t h e o r e t i c zero b i l e s a l t s e c r e t i o n was absent i n t h e younger groups, b u t evide n t i n t h e a d u l t and 25-30 d r a b b i t s . Canalicular flow estima t e d by e r y t h r i t o l clearance was l i n e a r l y (pC.01) r e l a t e d t o b i l e s a l t s e c r e t i o n . I n u l i n clearance r e l a t i v e t o e r y t h r i t o l clearance was h i g h e r i n 10-14 d i n f a n t s than adults.Thus, b i l e flow and b i l e s a l t s e c r e t i o n a r e reduced i n young a d u l t s , b u t r i s e t o n e a r a d u l t l e v e l s a t t h e time of weaning,25-30 d. The i n c r e a s e i n flow r e s u l t s from increased b i l e s a l t s e c r e t i o n and t h e appearance of b i l e salt-independent flow.In t h e young, increased b i l i a r y permeability maintains b i l e flow and c h l o r i d e output d e s p i t e increased b i l e s a l t s e c r e t i o n . AGE DEPENDENT DIFFERENCES I N SUPEROXIDE PRODUCTION BY STIMUZATED RAT KUPFFER CELLS IN THE PRESENCE OFUNINHIBITED TRYPSIN. Harvey L. Sharp,Judy Longsdorf i v e r s i t y of Minnesota, Department of P e d i a t r i c s , Minneapolis. The r o l e of o x i d a n t s i n hepatocyte i n j u r y i s c u r r e n t l y being considered. I n f a n t s and c h i l d r e n w i t h alAT deficiency a r e more prone t o hepatocyte i n j u r y than a d u l t s . We have begun i n v i t r o i n v e s t i g a t i o n s of t h e c e l l s c l o s e s t t o hepatocytes (Kupffer c e l l s ) i n regards t o t h e i r e x t r a c e l l u l a r superoxide production i n t h e presence o r absence of an u n i n h i b i t e d protease. Kupffer c e l l s were i s o l a t e d from r a t l i v e r by perfusion and incubation w i t h pronase, c e n t r i f u g a l e l u t r i a t i o n , and c u l t u r i n g f o r 24 hours. Over 95% of t h e c e l l s s t u d i e d were v i a b l e throughout t h e experiments a s determined by trypan blue exclusion and were i d e n t i f i e d a s Kupffer c e l l s by combined giemsa and peroxidase s t a i n i n g . Superoxide was determined i n HBSS by t h e reduction of cytochrome C i n t h e presence o r absence of superoxide d i smutase (SOD). Resting c e l l s produced e s s e n t i a l l y no SO.SO production ( n m o l e s l l . 5~1 0~ c e l l s 1 3 0 min) from t h e same r a t . . 080Trypsin (50 ug incubated f o r 20 minutes b e f o r e s t a r t of experiment). PMA (Phorbol m y r i s t a t e a c e t a t e .002 mg) . OpsonizedZymosan (1.25 mg). These r e s u l t s suggest t h a t Kupffer c e l l s from younger r a t s may respond d i f f e r e n t l y t o zymosan and PMA i n t h e production of o x i d a n t s i n t h e presence of a p r o t e a s e . TISSUE CARNITINE RESERVES O F NEWBORN INFANTS.Ja a n t P...