YF-12 propulsion research program and results

The objectives and status of the propulsion program, along with the results acquired in the various technology areas, are discussed. The instrumentation requirements for and experience with flight testing the propulsion systems at high supersonic cruise are reported. Propulsion system performance differences between wind tunnel and flight are given. The effects of high frequency flow fluctuations (transients) on the stability of the propulsion system are described, and shock position control is evaluated

Posterior intercostal artery tortuosity and collateral branch points: a cadaveric study

Publications report observing tortuosity in the posterior intercostal arteries of elderly patients.  Studies also describe the size and course of the collateral intercostal arteries. This information is clinically significant when performing thoracentesis and video-assisted thorascopic surgery (VATS). To the best of our knowledge, no studies have examined arterial tortuosity or described collateral artery origins relative to boney landmarks. The purpose of this study was to define a safe surgical zone for thoracic access using palpable external boney landmarks. Three-hundred forty-eight intercostal spaces (3rd – 8th) of 29 male and female embalmed cadavers were dissected from the vertebral body to the mid-axillary line to observe the posterior intercostal artery and its collateral branch. The origins of the collateral intercostal arteries relative to the midline of thoracic spinous processes were measured. Mild to moderate tortuosity (arterial curves covering 25-50% of the intercostal space) was observed in at least one posterior intercostal artery in the majority of cadavers. The origins of the collateral intercostal arteries were variable relative to the midline. Additional collateral intercostal arteries distal to the primary collateral branch were observed, most commonly in the 5th intercostal space, which is used in VATS and thoracentesis. Tortuosity is common in the third through eighth posterior intercostal arteries, especially in individuals over the age of 60. Given the findings of this study, we recommend that any procedure involving placement of a surgical instrument into these intercostal spaces do so at least 120 mm lateral to the midline of the spinous processes. We also recommend pre-procedure ultrasound (intercostals scan) of the posterior and collateral intercostal arteries when performing non-emergent thoracentesis and video-assisted thorascopic surgery, particularly in patients over 60 years of age

Quantification of the distal radial artery for improved vascular access

Background: There is no consensus in the literature as to which point of the radial artery (RA) is the safest to attempt vascular access. The purpose of this study was to measure the diameter, tortuosity and branching patterns of the distal RA. Materials and methods: 140 cadaveric RAs (66 male, 74 female) were dissected and measured. The external diameter of the RA was measured at 2 cm increments starting at the radial styloid process (SP), moving proximally. The location and degree of 2-dimensional arterial tortuosity were recorded if > 35 degrees. Branches of the RA were recorded with respect to their distance from the SP. Results: We observed that the right RA significantly increased in diameter at distances beyond 4 cm proximal from the radial SP, regardless of the sex of the individual. This increase in size was not noted on the left RA’s. Muscular artery branches of the distal RA were noted on average 1.82 cm proximal from the SP. Clinically significant tortuosity was present on average 3.47 cm proximal from the radial SP. The left RA did not significantly change in size along its course, but its statistically similar diameter when compared to the right RA allows us to make a recommendation this is applicable bilaterally. Conclusions: Our data suggests that regardless of gender, vascular access of the RA could be safely performed at distances greater than 4 cm from the SP to yield a vessel with a larger diameter, less tortuosity, and fewer branches

Variability in the anterior extralaryngeal branch of the recurrent laryngeal nerve: clinical implications

Background: This study aimed to identify the anterior and posterior extralaryngeal branches (AELB, PELB) of the recurrent laryngeal nerve (RLN), measure these branches when present, and determine relationships between gender, sidedness and neck length. Materials and methods: Dissection was completed to level of the thyroid on 45 cadavers. The course of the RLN was then traced superiorly from its entry into the neck. Careful reflection of the thyroid and dissection of the lateral thyroid ligament permitted visualisation of the full course of the nerve. If extralaryngeal branching (ELB) was present, measurements were taken from the point of bifurcation of the RLN to the point of laryngeal entry through the cricothyroid membrane. Neck measurements, from the spinous process of C7 to the superior nuchal line, were taken. Gender of the specimen was noted. Data was analysed in SPSS. Results: Extralaryngeal branching was found in 77.78% of our sample, 77.14% on the left and 54.29% on the right. A significant difference was found between AELB length on the left and right, indicating that the left branch will be longer than the right when present. A significant difference in neck length between those with and without ELB was also found, indicating that people with longer necks more often display ELB. Neither neck length and AELB length, nor gender and AELB length were strongly correlated in this sample. Conclusions: Extralaryngeal branching can occur in all populations, but there are definite trends in its incidence and length. Surgeons should be aware of these trends before operating on patients

Examination of the recommended safe and unsafe zone for placement of surgical instruments in thoracentesis and video-assisted thoracic surgery: a cadaveric study

Background: Thoracentesis and video-assisted thoracic surgery procedures can result in haemorrhage as a consequence of severing the collateral branches of the posterior intercostal artery. These branches have been shown to be most common in the 5th intercostal space (ICS). Tortuosity has been shown to be especially prevalent nearer to midline. A group of investigators have recommended the 4th and 7th ICS, 120 mm lateral to midline as a safe zone, least likely to hit branches when cutting into the ICS. The present study aimed to investigate that safe zone as a better entry points for procedures. In addition, investigation of the least safe 5th ICS was also performed. Materials and methods: A total of 56 embalmed human cadavers were selected for the study. With the cadavers laid prone, 2 cm incisions were made at the 4th, 5th and 7th ICS, 120 mm lateral to midline bilaterally. The cadavers were then placed supine and the incisions were dissected. Careful attention was paid to identify if any collateral branches were cut. Results: After thorough dissection of the 4th, 5th and 7th ICS incision sites, it was shown that damage to the 5th intercostal was seen most frequently. Conclusions: Based on this cadaveric study, a 2 cm incision at the 4th, 5th and 7th ICS 120 mm lateral from midline resulted in the most damage at the level of the 5th ICS. The 4th ICS had the least damage seen. Therefore, it is recommended that insertion should be placed at the level of the 4th ICS bilaterally

TEM Characterization of Solar Wind Effects on Genesis Mission Silicon Collectors

The Genesis Discovery Mission passively allowed solar wind (SW) to implant into substrates during exposure times up to ~853 days from 2001 to 2004. The spacecraft then returned the SW to Earth for analysis. Substrates included semiconductor wafers (silicon, sapphire, and germanium), as well as a number of thin films supported by either silicon or sapphire wafers. During flight, subsets of the SW collectors were exposed to one of 4 SW regimes: bulk solar wind, coronal hole solar wind (CH, high speed), interstream solar wind (IS, low speed) or coronal mass ejections (CMEs). Each SW regime had a different composition and range of ion speeds and, during their collection, uniquely changed their host SW collector. This study focuses on bulk vs IS SW effects on CZ silicon

Diverse viral glycoproteins as well as CD4 co-package into the same human immunodeficiency virus (HIV-1) particles

BACKGROUND: Retroviruses can acquire not only their own glycoproteins as they bud from the cellular membrane, but also some cellular and foreign viral glycoproteins. Many of these non-native glycoproteins are actively recruited to budding virions, particularly other viral glycoproteins. This observation suggests that there may be a conserved mechanism underlying the recruitment of glycoproteins into viruses. If a conserved mechanism is used, diverse glycoproteins should localize to a single budding retroviral particle. On the other hand, if viral glycoproteins have divergent mechanisms for recruitment, the different glycoproteins could segregate into different particles. RESULTS: To determine if co-packaging occurs among different glycoproteins, we designed an assay that combines virion antibody capture and a determination of infectivity based on a luciferase reporter. Virions were bound to a plate with an antibody against one glycoprotein, and then the infectivity was measured with cells that allow entry only with a second glycoprotein. We tested pairings of glycoproteins from HIV, murine leukemia virus (MLV), Rous sarcoma virus (RSV), vesicular stomatitis virus (VSV), and Ebola virus. The results showed that glycoproteins that were actively recruited into virions were co-packaged efficiently with each other. We also tested cellular proteins and found CD4 also had a similar correlation between active recruitment and efficient co-packaging, but other cellular proteins did not. CONCLUSION: Glycoproteins that are actively incorporated into HIV-1 virions are efficiently co-packaged into the same virus particles, suggesting that the same general mechanism for recruitment may act in many viruses

Tidal and thermal stresses drive seismicity along a major Ross Ice Shelf rift

Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters, 46(12), (2019): 6644-6652, doi:10.1029/2019GL082842.Understanding deformation in ice shelves is necessary to evaluate the response of ice shelves to thinning. We study microseismicity associated with ice shelf deformation using nine broadband seismographs deployed near a rift on the Ross Ice Shelf. From December 2014 to November 2016, we detect 5,948 icequakes generated by rift deformation. Locations were determined for 2,515 events using a least squares grid‐search and double‐difference algorithms. Ocean swell, infragravity waves, and a significant tsunami arrival do not affect seismicity. Instead, seismicity correlates with tidal phase on diurnal time scales and inversely correlates with air temperature on multiday and seasonal time scales. Spatial variability in tidal elevation tilts the ice shelf, and seismicity is concentrated while the shelf slopes downward toward the ice front. During especially cold periods, thermal stress and embrittlement enhance fracture along the rift. We propose that thermal stress and tidally driven gravitational stress produce rift seismicity with peak activity in the winter.NSF grants PLR‐1142518, 1141916, and 1142126 supported S. D. Olinger and D. A. Wiens, R. C. Aster, and A. A. Nyblade respectively. NSF grant PLR‐1246151 supported P. D. Bromirski, P. Gerstoft, and Z. Chen. NSF grant OPP‐1744856 and CAL‐DPR‐C1670002 also supported P. D. Bromirski. NSF grant PLR‐1246416 supported R. A. Stephen. The Incorporated Research Institutions for Seismology (IRIS) and the PASSCAL Instrument Center at New Mexico Tech provided seismic instruments and deployment support. The RIS seismic data (network code XH) are archived at the IRIS Data Management Center (http://ds.iris.edu/ds/nodes/dmc/). S. D. Olinger catalogued and located icequakes, analyzed seismicity and environmental forcing, and drafted the manuscript. D. A. Wiens and B. P. Lipovsky provided significant contributions to the analysis and interpretation of results and to the manuscript text. D. A. Wiens, R. C. Aster, A. A. Nyblade, R. A. Stephen, P. Gerstoft, and P. D. Bromirski collaborated to design and obtain funding for the deployment. D. A. Wiens, R. C. Aster, R. A. Stephen, P. Gerstoft, P. D. Bromirski, and Z. Chen deployed and serviced seismographs in Antarctica. All authors provided valuable feedback, comments, and edits to the manuscript text. Special thanks to Patrick Shore for guidance throughout the research process.2019-11-2

Universal criterion for the breakup of invariant tori in dissipative systems

The transition from quasiperiodicity to chaos is studied in a two-dimensional dissipative map with the inverse golden mean rotation number. On the basis of a decimation scheme, it is argued that the (minimal) slope of the critical iterated circle map is proportional to the effective Jacobian determinant. Approaching the zero-Jacobian-determinant limit, the factor of proportion becomes a universal constant. Numerical investigation on the dissipative standard map suggests that this universal number could become observable in experiments. The decimation technique introduced in this paper is readily applicable also to the discrete quasiperiodic Schrodinger equation.Comment: 13 page