Assembly of high-areal-density deuterium-tritium fuel from indirectly driven cryogenic implosions

The National Ignition Facility has been used to compress deuterium-tritium to an average areal density of ~1.0±0.1 g cm(-2), which is 67% of the ignition requirement. These conditions were obtained using 192 laser beams with total energy of 1-1.6 MJ and peak power up to 420 TW to create a hohlraum drive with a shaped power profile, peaking at a soft x-ray radiation temperature of 275-300 eV. This pulse delivered a series of shocks that compressed a capsule containing cryogenic deuterium-tritium to a radius of 25-35 μm. Neutron images of the implosion were used to estimate a fuel density of 500-800 g cm(-3).

Demonstration of ignition radiation temperatures in indirect-drive inertial confinement fusion hohlraums

We demonstrate the hohlraum radiation temperature and symmetry required for ignition-scale inertial confinement fusion capsule implosions. Cryogenic gas-filled hohlraums with 2.2 mm-diameter capsules are heated with unprecedented laser energies of 1.2 MJ delivered by 192 ultraviolet laser beams on the National Ignition Facility. Laser backscatter measurements show that these hohlraums absorb 87% to 91% of the incident laser power resulting in peak radiation temperatures of T(RAD)=300 eV and a symmetric implosion to a 100 μm diameter hot core.

A computer model of the position of the combined component in the prevention of impingement in total hip replacement

Dislocation remains a major concern after total hip replacement, and is often attributed to malposition of the components. The optimum position for placement of the components remains uncertain. We have attempted to identify a relatively safe zone in which movement of the hip will occur without impingement, even if one component is positioned incorrectly. A three-dimensional computer model was designed to simulate impingement and used to examine 125 combinations of positioning of the components in order to allow maximum movement without impingement. Increase in acetabular and/or femoral anteversion allowed greater internal rotation before impingement occurred, but decreases the amount of external rotation. A decrease in abduction of the acetabular components increased internal rotation while decreasing external rotation. Although some correction for malposition was allowable on the opposite side of the joint, extreme degrees could not be corrected because of bony impingement.

We introduce the concept of combined component position, in which anteversion and abduction of the acetabular component, along with femoral anteversion, are all defined as critical elements for stability.

Identification of chromosome inheritance modifiers in Drosophila melanogaster

Faithful chromosome inheritance is a fundamental biological activity and errors contribute to birth defects and cancer progression. We have performed a P-element screen in Drosophila melanogaster with the aim of identifying novel candidate genes involved in inheritance. We used a "sensitized" minichromosome substrate (J21A) to screen approximately 3,000 new P-element lines for dominant effects on chromosome inheritance and recovered 78 Sensitized chromosome inheritance modifiers (Scim). Of these, 69 decreased minichromosome inheritance while 9 increased minichromosome inheritance. Fourteen mutations are lethal or semilethal when homozygous and all exhibit dramatic mitotic defects. Inverse PCR combined with genomic analyses identified P insertions within or close to genes with previously described inheritance functions, including wings apart-like (wapl), centrosomin (cnn), and pavarotti (pav). Further, lethal insertions in replication factor complex 4 (rfc4) and GTPase-activating protein 1 (Gap1) exhibit specific mitotic chromosome defects, discovering previously unknown roles for these proteins in chromosome inheritance. The majority of the lines represent mutations in previously uncharacterized loci, many of which have human homologs, and we anticipate that this collection will provide a rich source of mutations in new genes required for chromosome inheritance in metazoans.

Molecular phylogeny and biogeography of Linanthus (Polemoniaceae)

To better understand the evolutionary history of Linanthus (Polemoniaceae) and its relatives, molecular phylogenies based on DNA sequence data from the internal transcribed spacer (ITS) region of nrDNA and the chloroplast gene matK were estimated using several methods. Our data suggest two separate and well-supported lineages of Linanthus in close association with two other genera-Leptodactylon and Phlox. These results agree with previous molecular systematic work on the Polemoniaceae, but do not support the traditional classification of the genus as a natural group, nor do they support the sectional classification within the genus. With a distribution centered primarily in western North America and a high degree of endemism in the California Floristic Province, it has been suggested by Raven and Axelrod that the origin and diversification of Linanthus and its relatives were tied to the development of a summer-dry climate in western North America, which began around 13-15 million years ago (mya). Increased drying during the Pliocene (1.2-5 mya) has also been hypothesized by Axelrod to have led to an increase in plant speciation in California and adjacent areas. Divergence times within the Linanthus lineages were estimated from the ITS and matK gene trees. A log-likelihood ratio test could not reject clock-like evolution for the matK data; however, the clock was strongly rejected for the ITS data set. Although ITS molecular evolution was not clock-like, the estimated times of divergence were similar to those of the matK data set. Within both lineages of Linanthus there seems to have been considerable diversification that has occurred since the Pliocene.

Comparison of home occult blood tests and interaction of tests with ibuprofen

The interaction of ibuprofen with home tests for occult blood was evaluated, and the accuracy of these tests was determined by validating the results with a specific quantitative assay of stool blood. Three home occult blood tests were evaluated: Early Detector, Fleet Detecatest, and CS-T Coloscreen Self Test. Fourteen men 19 to 35 years of age were instructed on how to use the tests and to record each day their dietary intake and stool consistency, the color of test control areas, the results, and the times of ibuprofen administration. The study consisted of a control period (days 0-5) and short-term (days 6-9) and long-term (days 10-14) ibuprofen periods. Each subject took two 200-mg tablets of ibuprofen three times daily beginning on day 6 and ending on day 14. During each study period, one stool sample was collected on each of three consecutive days. All three tests were performed on each sample, in addition to specific quantitative analysis with HemoQuant. All samples in the control period were negative for occult blood. Three positive results were reported by subject 4 in the short-term ibuprofen period, one with Fleet Detecatest and two with Early Detector. Subject 6 reported two positive Fleet Detecatest results and three positive Early Detector results during the long-term drug period. No positive results were detected with CS-T Coloscreen Self Test. The HemoQuant values showed that Early Detector produced one false-negative and two false-positive results.(ABSTRACT TRUNCATED AT 250 WORDS)

Derivation of VA/Q distribution from blood-gas tensions

Gas exchange was modelled by a Fortran program. Arterial blood-gas tensions have higher resolution than inert gas retentions in terms of distinguishing a single VA/Q compartment from a progressively broadening lognormal distribution. The maximum number of compartments determinable by arterial blood-gas tensions is three; VA/Q distributions containing more compartments are non-unique. Without utilizing 100% inspired oxygen, arterial blood-gas tensions cannot resolve the relative perfusion in shunt and low-VA/Q compartments, but the total perfusion in these compartments is determinable. The way in which the arterial blood-gas tensions vary with the variables of two and three-compartment distributions is described. Two- and three-compartment VA/Q distributions are derivable from either arterial blood-gas tensions or inert gas retentions.

Relationships among ventilation-perfusion distribution, multiple inert gas methodology and metabolic blood-gas tensions

The retention equations upon which the Multiple Inert Gas Method is based are derived from basic principles using elementary algebra. It is shown that widely disparate distributions produce indistinguishable sets of retentions. The limits of resolution of perfused compartments in the VA/Q distribution obtainable by the use of the multiple inert gas method are explored mathematically, and determined to be at most shunt and two alveolar compartments ("tripartite" distribution). Every continuous distribution studied produced retentions indistinguishable from those of its unique "matching" tripartite distribution. When a distribution is minimally specified, it is unique. Any additional specification (increased resolution--more compartments) of the distribution results in the existence of an infinitude of possible distributions characterized by indistinguishable sets of retention values. No further increase in resolution results from the use of more tracers. When sets of retention values were extracted from published multiple inert gas method continuous distributions, and compared with the published "measured" retention sets, substantial differences were found. This illustrates the potential errors incurred in the practical, in vivo application of the multiple inert gas method. In preliminary studies, the tripartite distribution could be determined with at least comparable accuracy by blood-gas (oxygen, carbon dioxide) measurements.

Hypoxemia and pulmonary gas exchange during hemodialysis

With measured values of arterial blood gas tensions, of expired respiratory gas fractions, and volume of the expired ventilation, the determinants of alveolar oxygen tension (PAO2) were used to evaluate their influence on the development of the arterial hypoxemia that occurs in spontaneously breathing patients undergoing hemodialysis using an acetate dialysate. Dialysis produced no significant changes in the alveolar-arterial O2 tension gradient (AaDO2). The extracorporeal dialyzer removed an average of 30 ml.m-2.min-1 of CO2. Accordingly the pulmonary gas exchange ratio (R) dropped from a mean predialysis value of 0.81 to 0.62 (P less than 0.001). The arterial CO2 tension remained constant throughout, whereas the minute ventilation, both total (P less than 0.01) and alveolar (P less than 0.01), decreased during dialysis. This decrease in ventilation accounts for more than 80% of the fall in PAO2. During dialysis there was a decrease (P less than 0.001) in arterial oxygen tension (PaO2), which varied among the individuals from 9 to 23% of control. During the postdialysis hour PaO2 returns to control values concomitant with increase in ventilation. The quantitative gas exchange relationships among R, alveolar ventilation, and AaDO2 predict the PaO2 values actually measured.

Surgical intervention to relieve dystocia in a python

The surgical procedure adopted to remove non-riable eggs from the oviduct of a python, Python anchitae, is described. Recovery was satisfactory, although it was not possible to establish whether reproduction was impaired. Reasons for the type of anaesthesia used and the choice of incision made are given.

Determinants of oxygen uptake during sodium bicarbonate infusion

Steady-state passive hyperventilation alkalosis produces a predictable increase in oxygen uptake (VO2) proportional to the change in arterial pH (pHa) while variable changes in VO2 have been reported during alkali infusion. To compare metabolic with respiratory alkalosis 17 dogs were anesthetized with halothane and their VO2 response to respiratory alkalosis evaluated by hyperventilation. The pHa measured during this phase was duplicated during the later continuous infusion of NaHCO3 at which time either 1) ventilation was held constant at the control level, allowing arterial carbon dioxide tension (PaCO2) to rise as a consequence of the bicarbonate dissociation, or 2) PaCO2 was held constant by servo control of ventilation. Hyperventilation (pHa 7.6, PaCO2 13 Torr) produced an average increase in VO2 of 24%. During the bicarbonate infusion at constant ventilation (pHa 7.6, PaCO2 45 Torr) VO2 increased only 7%; however, when PACO2 was held constant by servo ventilation VO2 increased 21% above control. We conclude that respiratory and metabolic alkalosis produce similar increases in VO2 when steady-state acid-base conditions are achieved.

Pulmonary shunting and lung volume during hypotension induced with trimetaphan

In 10 dogs anaesthetized with pentobarbitone mean Pa02 decreased from the control value of 13.5 kPa to 10.2 kPa, cardiac output decreased by 33%, and right-to-left shunt doubled during hypotension induced with trimetaphan. There was no signficant change in functional residual capacity during the period of hypotension or recovery. The hypoxaemia resulted from an increase in ventilation/perfusion inequality, with a decrease in arterial saturation consequent upon a decrease in cardiac output with a constant shunt. During the recovery period, right-to-left shunting remained greater than the values obtained before induction of hypotension.

Acute clinical hypocalcemic myocardial depression during rapid blood transfusion and postoperative hemodialysis: a preventable complication

Despite experimental evidence that myocardial depression resulting from rapid transfusion of ACD blood (citrate binds ionic calcium) is avoidable by simultaneous calcium administration, most hypovolemic patients receive calcium either after transfusion or not at all. Similar iatrogenic hypocalcemic myocardial depression occurs in normovolemic patients with known myocardial damage who are dialyzed for acute uremia when ACD blood prime is used at high initial flow rates (350 c.c. per minute) and when dialysis is performed against low calcium dialysate (2.5 mEq. per liter or less). This study tests the hypotheses that (1) rapid transfusion of as little as one unit of CPD blood causes a significant reduction in ionized calcium, (2) the depressive effect of CPD blood is significant and similar to that of ACD blood, (3) rapid blood transfusion (ACD or CPD) is safe if calcium is given simultaneously, (4) addition of calcium to the extracorporeal heparinized blood prime used in dialysis prevents initial depression, and (5) hemodynamic instability during dialysis is prevented when the dialysate is normocalcemic. From the results of our study, we made the following conclusions: (1) Ionized calcium is reduced significantly by rapid transfusion of CPD blood; (2) acute myocardial depression noted with CPD blood is similar to that previously observed with ACD blood and is prevented during transfusion of either type of blood by simultaneous calcium administration; and (3) hemodialysis in patients who have had cardiac surgery is safe if calcium is added to blood prime and dialysate is made normocalcemic.

Effect of PaCO2 on O2 consumption during cardiopulmonary bypass in man

Under conditions of anesthesia with controlled respiration, the changes in the state of the circulation due to altered PaCO2 are often overlooked or attributed to the anesthetic agent. During cardiopulmonary bypass when cardiac output is kept constant, change in fluid level of the extracorporeal reservoir reflects overall change in the circulatory beds. Following an hour on total bypass for stabilization of all parameters, a change in the oxygenator ventilating-gas mixture was induced to increase or decrease the PaCO2 an average of 11 torr in 40 patients. A reduction in PaCO2 from 37 to 25 torr increased mean arterial blood pressure (MAP), central venous pressure (CVP), and the volume of blood stored in the extracorporeal circuit, signifying an overall reduction in the intravascular capacity. This was associated with a decrease in total O2 consumption (VO2). An abrupt increase of PaCO2 from 26 to 37 torr produced a decrease in MAP,in CVP, and in the reservoir blood level, signifying blood "take up" by the patient. There was also an associated increase in VO2.

Effect of airway hypocapnia on mechanics of breathing during cardiopulmonary bypass

Total cardiopulmonary bypass separates the lungs from the pulmonary arterial circulation. Continued ventilation with non CO 2 -containing mixtures during bypass will result in airway hypocapnia. Airway hypocapnia results in decreased compliance, increased work of breathing, and increased resistance to air flow. Reversal of airway hypocapnia increased compliance one-third, decreased work of breathing 20%, and decreased air flow resistance approximately 40% when compared to the values obtained during the period of low airway CO 2 . These changes in airway mechanics must be considered for pulmonary management during cardiac bypass.