Cardiac output and regional blood flow in conscious rats exposed to acute hypoxia

Cardiac output and regional blood flow in conscious rats exposed to acute hypoxi

Fundamental results from microgravity cell experiments with possible commericial applications

Some of the major milestones are presented for studies in cell biology that were conducted by the Soviet Union and the United States in the upper layers of the atmosphere and in outer space for more than thirty-five years. The goals have changed as new knowledge is acquired and the priorities for the use of microgravity have shifted toward basic research and commercial applications. Certain details concerning the impact of microgravity on cell systems is presented. However, it needs to be emphasized that in planning and conducting microgravity experiments, there are some important prerequisites not normally taken into account. Apart from the required background knowledge of previous microgravity and ground-based experiments, the investigator should have the understanding of the hardware as a physical unit, the complete knowledge of its operation, the range of its capabilities and the anticipation of problems that may occur. Moreover, if the production of commercial products in space is to be manifested, data obtained from previous microgravity experiments must be used to optimize the design of flight hardware

Precision spectra of A\, ^2\Sigma^+,v'=0 \leftarrow X\, ^2\Pi_{3/2},v''=0,J''=3/2 transitions in 16^{16}OH and 16^{16}OD

We report absolute optical frequencies of electronic transitions from the X\, ^2\Pi_{3/2},v''=0,J''=3/2 rovibronic ground state to the 12 lowest levels of the A\, ^2\Sigma^+,v'=0 vibronic state in $^{16}$OH, as well as to the 16 lowest levels of the same vibronic state in $^{16}$OD. The absolute frequencies of these transitions have been determined with a relative uncertainty of a few parts in $10^{11}$, representing a $\sim$1000-fold improvement over previous measurements. To reach this level of precision, an optical frequency comb has been used to transfer the stability of a narrow-linewidth I$_2$-stabilized reference laser onto the 308-nm spectroscopy laser. The comb is also used to compare the optical frequency of the spectroscopy laser to an atomic clock reference, providing absolute accuracy. Measurements have been carried out on OH/OD molecules in a highly-collimated molecular beam, reducing possible pressure shifts and minimizing Doppler broadening. Systematic shifts due to retroreflection quality, the Zeeman effect, and the ac Stark effect have been considered during the analysis of the measured spectra; particularly in the case of the OD isotopologue, these effects can result in shifts of the fitted line positions of as much as 300 kHz. The transition frequencies extracted in the analysis were also used to determine spectroscopic constants for the A\, ^2\Sigma^+,v'=0 vibronic state. The constants fitted in this work differ significantly from those reported in previous works that measured the $A - X$ transitions, resulting in typical deviations of the predicted optical transition frequencies of $\sim$150 MHz, but they generally agree quite well with the constants determined using hyperfine-resolved measurements of splittings within the $A$ state.Comment: 13 pages, 4 figure

Improving Follow Up Compliance for Patients with Sleep Disordered Breathing at Jefferson Sleep Center

Despite the high effectiveness of CPAP therapy, patient adherence remains variable and a hurdle towards appropriate treatment of their sleep-disordered breathing. Patients often stop using their CPAP and are then lost to follow-up, which increases their risk of previously mentioned complications that are associated with OSA. Goals for Improvement To increase the follow-up rate for patients with OSA

Einstein-de Haas torque as a discrete spectroscopic probe allows nanomechanical measurement of a magnetic resonance

The Einstein-de Haas (EdH) effect is a fundamental, mechanical consequence of any temporal change of magnetism in an object. EdH torque results from conserving the object's total angular momentum: the angular momenta of all the specimen's magnetic moments, together with its mechanical angular momentum. Although the EdH effect is usually small and difficult to observe, it increases in magnitude with detection frequency. We explore the frequency-dependence of EdH torque for a thin film permalloy microstructure by employing a ladder of flexural beam modes (with five distinct resonance frequencies spanning from 3 to 208 MHz) within a nanocavity optomechanical torque sensor via magnetic hysteresis curves measured at mechanical resonances. At low DC fields the gyrotropic resonance of a magnetic vortex spin texture overlaps the 208 MHz mechanical mode. The massive EdH mechanical torques arising from this co-resonance yield a fingerprint of vortex core pinning and depinning in the sample. The experimental results are discussed in relation to mechanical torques predicted from both macrospin (at high DC magnetic field) and finite-difference solutions to the Landau-Lifshitz-Gilbert (LLG) equation. A global fit of the LLG solutions to the frequency-dependent data reveals a statistically significant discrepancy between the experimentally observed and simulated torque phase behaviours at spin texture transitions that can be reduced through the addition of a time constant to the conversion between magnetic cross-product torque and mechanical torque, constrained by experiment to be in the range of 0.5 - 4 ns.Comment: 39 pages, 17 figures total (Main: 22 pages, 8 figures; Supplement: 17 pages, 9 figures