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Unitized regenerative fuel cell systems
Energy storage systems with extremely high specific energy (>400 Wh/kg) have been designed that use lightweight pressure vessels to contain the gases generated by reversible (unitized) regenerative fuel cells (URFCs).[1] URFC systems are being designed and developed for a variety of applications, including high altitude long endurance (HALE) solar rechargeable aircraft (SRA), zero emission vehicles (ZEVs), hybrid energy storage/propulsion systems for spacecraft, energy storage for remote (off-grid) power sources, and peak shaving for on-grid applications.[1-10] Energy storage for HALE SRA was the original application for this set of innovations, and a prototype solar powered aircraft (Pathfinder-Plus) recently set another altitude record for all propeller-driven aircraft on August 6, 1998, when it flew to 80,285 feet (24.47 km).[11
Management of imatinib-resistant CML patients
Imatinib has had marked impact on outcomes in chronic myelogenous leukemia (CML) patients for all stages of the disease and is endorsed by international treatment guidelines as the first line option. Although imatinib is highly effective and well tolerated, the development of resistance represents a clinical challenge. Since the most frequently identified mechanism of acquired imatinib resistance is bcr-abl kinase domain point mutations, periodic hematologic, cytogenetic, and molecular monitoring is critical throughout imatinib therapy. Once cytogenetic remission is achieved, residual disease can be monitored by bcr-abl transcript levels as assayed by reverse transcription polymerase chain reaction (RT-PCR). Detection of bcr-abl mutants prior to and during imatinib therapy can aid in risk stratification as well as in determining therapeutic strategies. Thus, mutation screening is indicated in patients lacking or losing hematologic response. Moreover, search for mutations should also be performed when a 3-log reduction of bcr-abl transcripts is not achieved or there is a reproducible increase of transcript levels. In patients harboring mutations which confer imatinib resistance, novel second line tyrosine kinase inhibitors have demonstrated encouraging efficacy with low toxicity. Only the T315I bcr-abl mutant has proved totally resistant to all clinically available bcr-abl inhibitors. Strategies to further increase the rates of complete molecular remissions represent the next frontier in the targeted therapy of CML patients
International Federation of Clinical Chemistry (IFCC): Scientific Division, Committee on pH, Blood Gases and Electrolytes: Guidelines for Transcutaneouspo2andpco2 Measurement
This document provides guidelines for the terminology, methodology,
and for the interpretation of data obtained from the use of skin
(transcutaneous) po2 and pco2 electrodes. The transcutaneous
technique has found special application in newborn infants. The
causes of analytical bias with respect to arterial blood gas values,
and imprecision obtained with transcutaneous pco2 electrodes, are reviewed. Electrode temperatures above 44°C should not be used
routinely, and, at a measuring temperature of 44°C, the measuring
site should be changed at least every 4 h to avoid skin burns
The Strange Prospects for Astrophysics
The implications of the formation of strange quark matter in neutron stars
and in core-collapse supernovae is discussed with special emphasis on the
possibility of having a strong first order QCD phase transition at high baryon
densities. If strange quark matter is formed in core-collapse supernovae
shortly after the bounce, it causes the launch of a second outgoing shock which
is energetic enough to lead to a explosion. A signal for the formation of
strange quark matter can be read off from the neutrino spectrum, as a second
peak in antineutrinos is released when the second shock runs over the
neutrinosphere.Comment: 10 pages, 8 figures, invited talk given at the international
conference on strangeness in quark matter (SQM2008), Beijing, October 6-10,
Beijing, China, version to appear in J. Phys.
Electrolysis Propulsion for Spacecraft Applications
Electrolysis propulsion has been recognized over the last several decades as a viable option to meet many satellite and spacecraft propulsion requirements. This technology, however, was never used for in-space missions. In the same time frame, water based fuel cells have flown in a number of missions. These systems have many components similar to electrolysis propulsion systems. Recent advances in component technology include: lightweight tankage, water vapor feed electrolysis, fuel cell technology, and thrust chamber materials for propulsion. Taken together, these developments make propulsion and/or power using electrolysis/fuel cell technology very attractive as separate or integrated systems. A water electrolysis propulsion testbed was constructed and tested in a joint NASA/Hamilton Standard/Lawrence Livermore National Laboratories program to demonstrate these technology developments for propulsion. The results from these testbed experiments using a I-N thruster are presented. A concept to integrate a propulsion system and a fuel cell system into a unitized spacecraft propulsion and power system is outlined
The Relationship Between Belief and Credence
Sometimes epistemologists theorize about belief, a tripartite attitude on which one can believe, withhold belief, or disbelieve a proposition. In other cases, epistemologists theorize about credence, a fine-grained attitude that represents one’s subjective probability or confidence level toward a proposition. How do these two attitudes relate to each other? This article explores the relationship between belief and credence in two categories: descriptive and normative. It then explains the broader significance of the belief-credence connection and concludes with general lessons from the debate thus far
The Evolution of PSR J0737-3039B and a Model for Relativistic Spin Precession
We present the evolution of the radio emission from the 2.8-s pulsar of the
double pulsar system PSR J0737-3039A/B. We provide an update on the Burgay et
al. (2005) analysis by describing the changes in the pulse profile and flux
density over five years of observations, culminating in the B pulsar's radio
disappearance in 2008 March. Over this time, the flux density decreases by
0.177 mJy/yr at the brightest orbital phases and the pulse profile evolves from
a single to a double peak, with a separation rate of 2.6 deg/yr. The pulse
profile changes are most likely caused by relativistic spin precession, but can
not be easily explained with a circular hollow-cone beam as in the model of
Clifton & Weisberg (2008). Relativistic spin precession, coupled with an
elliptical beam, can model the pulse profile evolution well. This particular
beam shape predicts geometrical parameters for the two bright orbital phases
which are consistent and similar to those derived by Breton et al. (2008).
However, the observed decrease in flux over time and B's eventual disappearance
cannot be easily explained by the model and may be due to the changing
influence of A on B.Comment: 20 pages, 18 figures, Accepted by ApJ on 2 August 201
The Wisconsin Plasma Astrophysics Laboratory
The Wisconsin Plasma Astrophysics Laboratory (WiPAL) is a flexible user
facility designed to study a range of astrophysically relevant plasma processes
as well as novel geometries that mimic astrophysical systems. A multi-cusp
magnetic bucket constructed from strong samarium cobalt permanent magnets now
confines a 10 m, fully ionized, magnetic-field free plasma in a spherical
geometry. Plasma parameters of to eV and
to cm provide an ideal testbed
for a range of astrophysical experiments including self-exciting dynamos,
collisionless magnetic reconnection, jet stability, stellar winds, and more.
This article describes the capabilities of WiPAL along with several
experiments, in both operating and planning stages, that illustrate the range
of possibilities for future users.Comment: 21 pages, 12 figures, 2 table
Circular Polarization in Pulsar Integrated Profiles: Updates
We update the systematic studies of circular polarization in integrated pulse
profiles by Han et al (1998). Data of circular polarization profiles are
compiled. Sense reversals can occur in core or cone components, or near the
intersection between components. The correlation between the sense of circular
polarization and the sense of position angle variation for conal-double pulsars
is confirmed with a much large database. Circular polarization of some pulsars
has clear changes with frequency. Circular polarization of millisecond pulsars
is marginally different from that of normal pulsars.Comment: 10 pages, 6 figures, accepted and will be published soon by Chinese
Journal of Astronomy and Astrophysics (ChJAA
Observations and Modelling of Relativistic Spin Precession in PSR J1141-6545
Observations of the binary pulsar PSR J1141-6545 using the Parkes radio
telescope over 9.3 years show clear time-variations in pulse width, shape and
polarization. We interpret these variations in terms of relativistic precession
of the pulsar spin axis about the total angular momentum vector of the system.
Over the nine years, the pulse width at the 50% level has changed by more than
a factor of three. Large variations have also been observed in the 1400-MHz
mean flux density. The pulse polarization has been monitored since 2004 April
using digital filterbank systems and also shows large and systematic variations
in both linear and circular polarization. Position angle variations, both
across the pulse profile and over the data span, are complex, with major
differences between the central and outer parts of the pulse profile. Modelling
of the observed position angle variations by relativistic precession of the
pulsar spin axis shows that the spin-orbit misalignment angle is about 110 deg
and that the precessional phase has passed through 180 deg during the course of
our observations. At the start of our observations, the line-of-sight impact
parameter was about 4 deg in magnitude and it reached a minimum very close to 0
deg around early 2007, consistent with the observed pulse width variations. We
have therefore mapped approximately one half of the emission beam, showing that
it is very asymmetric with respect to the magnetic axis. The derived
precessional parameters imply that the pre-supernova star had a mass of about 2
Msun and that the supernova recoil kick velocity was relatively small. With the
reversal in the rate of change of the impact parameter, we predict that over
the next decade we will see a reversed "replay" of the variations observed in
the past decade.Comment: 45 pages, 19 figures, 6 tables, accepted by Astrophysical Journa
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