Study of cryogenic fluid mixing techniques. Volume 1 - Large-scale experimental mixing investigations and liquid-oxygen mixer design Final report

Large-scale experimental liquid hydrogen mixing and liquid oxygen mixer desig

Study of cryogenic fluid mixing techniques. Volume 2 - Large-scale mixing data Final report, Jul. 1969 - Jul. 1970

Basic mixing data and dimensionless correlations for 52 tests in large-scale stratified mixing tank for cryogenic rocket propellant

A study of cryogenic propellant mixing techniques. Volume 1 - Mixer design and experimental investigations Final report, Jul. 1967 - Sep. 1968

Mixer design and experimental tank study for cryogenic propellants, with applications for manned Mars missio

Influence of Normal Daytime Fat Deposition on Laboratory Measurements of Torpor Use in Territorial versus Nonterritorial Hummingbirds

Fat deposition and torpor use in hummingbirds exhibiting distinct foraging styles should vary. We predicted that dominant territorial hummingbirds will use torpor less than subordinate nonterritorial species because unrestricted access to energy by territory owners allows for fat storage. Entry into torpor was monitored using open-flow respirometry on hummingbirds allowed to accumulate fat normally during the day. Fat accumulation was measured by solvent fat extraction. Territorial blue-throated hummingbirds (Lampornis clemenciae) had the highest fat accumulation and used torpor only 17% of the time. Fat storage by L. clemenciae averaged 26% of lean dry mass (LDM) in 1995 and 18% in 1996, similar to that measured for other nonmigratory birds. Fat storage by magnificent hummingbirds (Eugenes fulgens; trapliner) and black-chinned hummingbirds (Archilochus alexandri; nectar robber) averaged 19% and 16% of LDM, respectively, and they used torpor frequently (64% and 92% of the time, respectively). All species initiated torpor if total body fat dropped below 10% of LDM, indicating the existence of a torpor threshold. The ability of L. clemenciae to store enough fat to support nighttime metabolism is likely an important benefit of territoriality. Likewise, frequent torpor use by subordinates suggests that natural restrictions to energy intake can impact their energy budget, necessitating energy conservation by use of torpor

Magnetodielectric coupling in Mn3O4

We have investigated the dielectric anomalies associated with spin ordering transitions in the tetragonal spinel Mn$_3$O$_4$, using thermodynamic, magnetic, and dielectric measurements. We find that two of the three magnetic ordering transitions in Mn$_3$O$_4$ lead to decreases in the temperature dependent dielectric constant at zero applied field. Applying a magnetic field to the polycrystalline sample leaves these two dielectric anomalies practically unchanged, but leads to an increase in the dielectric constant at the intermediate spin-ordering transition. We discuss possible origins for this magnetodielectric behavior in terms of spin-phonon coupling. Band structure calculations suggest that in its ferrimagnetic state, Mn$_3$O$_4$ corresponds to a semiconductor with no orbital degeneracy due to strong Jahn-Teller distortion.Comment: 6 pages, 7 figure

Breaking the Disk/Halo Degeneracy with Gravitational Lensing

The degeneracy between the disk and the dark matter contribution to galaxy rotation curves remains an important uncertainty in our understanding of disk galaxies. Here we discuss a new method for breaking this degeneracy using gravitational lensing by spiral galaxies, and apply this method to the spiral lens B1600+434 as an example. The combined image and lens photometry constraints allow models for B1600+434 with either a nearly singular dark matter halo, or a halo with a sizable core. A maximum disk model is ruled out with high confidence. Further information, such as the circular velocity of this galaxy, will help break the degeneracies. Future studies of spiral galaxy lenses will be able to determine the relative contribution of disk, bulge, and halo to the mass in the inner parts of galaxies.Comment: Replaced with minor revisions, a typo fixed, and reference added; 21 pages, 8 figures, ApJ accepte

Meatal Swabs Contain Less Cellular Material and Are Associated with a Decrease in Gram Stain Smear Quality Compared to Urethral Swabs in Men

Urethral swabs are the samples of choice for point-of-care Gram stain testing to diagnose Neisseria gonorrhoeae infection and nongonococcal urethritis (NGU) in men. As an alternative to urethral swabs, meatal swabs have been recommended for the collection of urethral discharge to diagnose N. gonorrhoeae and Chlamydia trachomatis infection in certain populations by nucleic acid amplification testing (NAAT), as they involve a less invasive collection method. However, as meatal swabs could be sampling a reduced surface area and result in fewer collected epithelial cells compared to urethral swabs, the adequacy of meatal swab specimens to collect sufficient cellular material for Gram stain testing remains unknown. We enrolled 66 men who underwent either urethral or meatal swabbing and compared the cellular content and Gram stain failure rate. We measured the difference in swab cellular content using the Cepheid Xpert CT/NG sample adequacy control crossing threshold (SACCT) and determined the failure rate of Gram stain smears (GSS) due to insufficient cellular material. In the absence of discharge, meatal smears were associated with a significant reduction in cellular content (P = 0.0118), which corresponded with a GSS failure rate significantly higher than that for urethral swabs (45% versus 3%, respectively; P < 0.0001). When discharge was present, there was no difference among results from urethral and meatal swabs. Therefore, if GSS testing is being considered for point-of-care diagnosis of N. gonorrhoeae infection or NGU in men, meatal swabs should be avoided in the absence of a visible discharge

Delay in Seeking Healthcare Services Following Onset of Urethritis Symptoms in Men

Background: Symptom awareness, behavioral factors, and other barriers associated with timely sexually transmitted infection (STI) health care provision in men is not well studied. Methods: Men attending an STI clinic answered a questionnaire regarding their symptoms, sexual behavior, and sociodemographic and behavioral characteristics. Characteristics of symptomatic men were compared between those who did and did not delay seeking health care services. Delayed care seeking was defined as clinic attendance longer than 7 days after symptoms, whereas early care seeking was defined as clinic attendance of 7 days or less. Results: Over a quarter (n = 43 [27.7%]) of men with urethritis symptoms (urethral discharge or dysuria) delayed seeking care for more than 7 days. Compared with men who sought treatment within 7 days, those that delayed care worried for longer periods that their symptoms were STI-related, were more likely to attempt self-treatment of STI symptoms, were more likely to continue engaging in sexual activity, and were less likely to use a condom during their last sexual encounter. Conversely, men that delayed care seeking were less likely to have urethral discharge on physical examination, to have 5 or more polymorphonuclear leukocytes, and to test positive for Neisseria gonorrhoeae. When compared with men that sought care earlier, men that delayed care seeking had fewer overall and new partners in the past 30 days. Conclusions: Our data suggest that over a quarter of men aware of STI symptoms delay seeking health services. Interventions that promote better patient understanding of the importance of symptom recognition and that facilitate timely access to care may provide new opportunities to reduce STI transmission