962 research outputs found
Concentric differential gearing arrangement
Two input members and two concentric rotatable output members are interconnected by a planetary gear arrangement. The first input drives directly the first output. The second input engages a carrier having the planetary gears affixed thereto. Rotation of the carriage causes rotation of the central sun gear of the planetary gear system. The sun gear is journaled to the carriage and is drivingly connected to the second output through a direction reversing set of bevel gears. The first input drive member includes a ring gear drivingly connected to the planetary gears for driving the second output member in the same direction and by the same amount as the first output member. Motion of the first input results in equal motion of the two outputs while input motion of the second input results in movement of the second output relative to the first output. This device is useful where non-interacting two-axis control of remote gimbaled systems is required
Mechanical planetary compensating drive system
Drive enables two concentric output shafts to be controlled independently or rotated as a unit. Possible uses are pointing and tracking devices, rotary camera shutters with variable light control, gimbal systems with yaw and pitch movement, spectrometer mirror scanning devices, etc
Design of Optical/IR Blocking Filters for the Lynx X-Ray Microcalorimeter
The Lynx mission concept, under development ahead of the 2020 Astrophysics Decadal Review, includes the Lynx X-ray Microcalorimeter (LXM) as one of its primary instruments. The LXM uses a microcalorimeter array at the focus of a high-throughput soft x-ray telescope to enable high-resolution nondispersive spectroscopy in the soft x-ray waveband (0.2 to 15 keV) with exquisite angular resolution. Similar to other x-ray microcalorimeters, the LXM uses a set of blocking filters mounted within the dewar that pass the photons of interest (x-rays) while attenuating the out-of-band long-wavelength radiation. Such filters have been successfully used on previous orbital and suborbital instruments; however, the Lynx science objectives, which emphasize observations in the soft x-ray band (<1keV), pose more challenging requirements on the set of LXM blocking filters. We present an introduction to the design of the LXM optical/IR blocking filters and discuss recent advances in filter capability targeted at LXM. In addition, we briefly describe the external filters and the modulated x-ray sources to be used for onboard detector calibration
Proper Motions of PSRs B1757-24 and B1951+32: Implications for Ages and Associations
Over the last decade, considerable effort has been made to measure the proper
motions of the pulsars B1757-24 and B1951+32 in order to establish or refute
associations with nearby supernova remnants and to understand better the
complicated geometries of their surrounding nebulae. We present proper motion
measurements of both pulsars with the Very Large Array, increasing the time
baselines of the measurements from 3.9 yr to 6.5 yr and from 12.0 yr to 14.5
yr, respectively, compared to previous observations. We confirm the
non-detection of proper motion of PSR B1757-24, and our measurement of (mu_a,
mu_d) = (-11 +/- 9, -1 +/- 15) mas yr^{-1} confirms that the association of PSR
B1757-24 with SNR G5.4-1.2 is unlikely for the pulsar characteristic age of
15.5 kyr, although an association can not be excluded for a significantly
larger age. For PSR B1951+32, we measure a proper motion of (mu_a, mu_d) =
(-28.8 +/- 0.9, -14.7 +/- 0.9) mas yr^{-1}, reducing the uncertainty in the
proper motion by a factor of two compared to previous results. After correcting
to the local standard of rest, the proper motion indicates a kinetic age of ~51
kyr for the pulsar, assuming it was born near the geometric center of the
supernova remnant. The radio-bright arc of emission along the pulsar proper
motion vector shows time-variable structure, but moves with the pulsar at an
approximately constant separation ~2.5", lending weight to its interpretation
as a shock structure driven by the pulsar.Comment: LaTeX file uses emulateapj.cls; 7 pages, 4 figures, to be published
ApJ February 10, 2008, v674 p271-278. Revision reflects journal formatting;
there are no substantial revision
Bactericidal activity of extended 9-glycyl-amido-minocyclines
The need for self-protecting polymer or alloy implants resistant to a broad spectrum of bacterial challenges led us to investigate covalent bonding of minocycline (MIN), a tetracycline derivative, to polystyrene beads and to titanium alloy foils by oligoethylene glycol spacers. 9-Hydrazino-acetyl-amido-MIN, and simpler glycylcycline derivatives, retained minimum inhibitory concentration (MIC) against Staphylococcus aureus comparable to MIN. However, PEG-glycyl-amido-MIN showed very low activity. Hence, we coupled 9-hydrazino-acetyl-amido-MIN to the aldehyde termini of oligoethylene glycol spacers bonded to polystyrene and titanium alloy surfaces to form acid-releasable hydrazone linkages. 9-Hydrazino-acetyl-amido-MIN was released from the monolayers more rapidly at pH 5.0 than at pH 7.4
Pharmacogenomic Considerations in Opioid Therapy
Opioids are among the most common medications used in the treatment of pain, and they carry many serious risks if used inappropriately. Pharmacogenomic considerations can impact a patient’s treatment plan for chronic pain, as CYP polymorphisms may interfere with nonsteroidal anti-inflammatory drugs, tricyclic antidepressants, and opioids. In particular, CYP2D6 polymorphisms may play a considerable part in the safety and efficacy of codeine, hydrocodone, and tramadol, as outlined in the Clinical Pharmacogenetic Implementation Consortium (CPIC) guideline on opioids. Based on current research, the CPIC recently updated its guidance on opioid use and interactions with CYP2D6, OPRM1, and COMT polymorphisms. Greater pharmacist understanding of CYP polymorphisms can lead to safer opioid prescribing and better outcomes for patients receiving pain management
Symptoms in pediatric asthmatics and air pollution: differences in effects by symptom severity, anti-inflammatory medication use and particulate averaging time.
Experimental research in humans and animals points to the importance of adverse respiratory effects from short-term particle exposures and to the importance of proinflammatory effects of air pollutants, particularly O(subscript)3. However, particle averaging time has not been subjected to direct scientific evaluation, and there is a lack of epidemiological research examining both this issue and whether modification of air pollutant effects occurs with differences in asthma severity and anti-inflammatory medication use. The present study examined the relationship of adverse asthma symptoms (bothersome or interfered with daily activities or sleep) to O(3) and particles (less than or equal to)10 micrometer (PM10) in a Southern California community in the air inversion zone (1200-2100 ft) with high O(3) and low PM (R = 0.3). A panel of 25 asthmatics 9-17 years of age were followed daily, August through October 1995 (n = 1,759 person-days excluding one subject without symptoms). Exposures included stationary outdoor hourly PM10 (highest 24-hr mean, 54 microgram/m(3), versus median of 1-hr maximums, 56 microgram/m(3) and O(3) (mean of 1-hr maximums, 90 ppb, 5 days (greater than or equal to)120 ppb). Longitudinal regression analyses utilized the generalized estimating equations (GEE) model controlling for autocorrelation, day of week, outdoor fungi, and weather. Asthma symptoms were significantly associated with both outdoor O(3) and PM(10) in single pollutant- and co-regressions, with 1-hr and 8-hr maximum PM(10) having larger effects than the 24-hr mean. Subgroup analyses showed effects of current day PM(10) maximums were strongest in 10 more frequently symptomatic (MS) children: the odds ratios (ORs) for adverse symptoms from 90th percentile increases were 2.24 [95% confidence interval (CI), 1.46-3.46] for 1-hr PM10 (47 microgram/m(3); 1.82 (CI, 1.18-2.81) for 8-hr PM10 (36 microgram/m(3); and 1.50 (CI, 0.80-2.80) for 24-hr PM10 (25 microgram/m(3). Subgroup analyses also showed the effect of current day O(subscript)3 was strongest in 14 less frequently symptomatic (LS) children: the ORs were 2.15 (CI, 1.04-4.44) for 1-hr O(3) (58 ppb) and 1.92 (CI, 0.97-3.80) for 8-hr O(3) (46 ppb). Effects of 24-hr PM10 were seen in both groups, particularly with 5-day moving averages (ORs were 1.95 for MS and 4. 03 for LS; p(less than or equal to)0.05). The largest effects were in 7 LS children not on anti-inflammatory medications [5-day, 8-hr PM10, 9.66 (CI, 2.80-33.21); current day, 1-hr O(3), 4.14 (CI, 1.71-11.85)]. Results suggest that examination of short-term particle excursions, medication use, and symptom severity in longitudinal studies of asthma yields sensitive measures of adverse respiratory effects of air pollution
Processing and Transmission of Information
Contains reports on four research projects.Lincoln Laboratory, Purchase Order DDL-B222U.S. Air Force under Air Force Contract AF19(604)-520
Giant lasing effect in magnetic nanoconductors
We propose a new principle for a compact solid-state laser in the 1-100 THz
regime. This is a frequency range where attempts to fabricate small size lasers
up till now have met severe technical problems. The proposed laser is based on
a new mechanism for creating spin-flip processes in ferromagnetic conductors.
The mechanism is due to the interaction of light with conduction electrons; the
interaction strength, being proportional to the large exchange energy, exceeds
the Zeeman interaction by orders of magnitude. On the basis of this
interaction, a giant lasing effect is predicted in a system where a population
inversion has been created by tunneling injection of spin-polarized electrons
from one ferromagnetic conductor to another -- the magnetization of the two
ferromagnets having different orientations. Using experimental data for
ferromagnetic manganese perovskites with nearly 100% spin polarization we show
the laser frequency to be in the range 1-100 THz. The optical gain is estimated
to be of order 10^7 cm^{-1}, which exceeds the gain of conventional
semiconductor lasers by 3 or 4 orders of magnitude. A relevant experimental
study is proposed and discussed.Comment: 4 pages, 3 figure
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