1,216 research outputs found
Synthesis of water-soluble chiral DOTA lanthanide complexes with predominately twisted square antiprism isomers and circularly polarized luminescence emission
One-step cyclization of a tetraazamacrocycle 5 with 70% yield in a 25-g scale was performed. Its chiral DOTA derivatives, L4, has ∼93% of TSAP coordination isomer in its Eu(III) and Yb(III) complexes in aqueous solution. [GdL4]5– exhibits a high relaxivity, making it a promising and efficient MRI contrast agent. High luminescence dissymmetry factor (glum) values of 0.285 (ΔJ = 1) for [TbL3]– and 0.241 (ΔJ = 1) for [TbL4]5– in buffer solutions were recorded
A Search for X-Ray Flashes with XMM-Newton
We searched for X-ray flashes (XRFs) -- which we defined as ~10s duration
transient X-ray events observable in the 0.4-15 keV passband -- in fields
observed using XMM-Newton with the EPIC/pn detector. While we find two
non-Poissonian events, the astrophysical nature of the events is not confirmed
in fully simultaneous observations with the EPIC/MOS detectors, and we conclude
that the events are anomalous to the EPIC/pn detector. We find a 90% upper
limit on the number of flashes per sky per year at two different incoming flash
fluxes: 4.0x10^9 events / sky / year for a flux of 7.1x10^-13 erg / cm^2 / s
and 6.8x10^7 events / sky / year for 1.4x10^-11 erg / cm^2 / s. These limits
are consistent with an extrapolation from the BeppoSAX/WFC XRF rate at much
higher fluxes (about a factor of 10^5), assuming an homogenous population, and
with a previous, more stringent limit derived from ROSAT pointed observations.Comment: Version accepted by MNRAS (minor changes
The Factory and The Beehive I. Rotation Periods For Low-Mass Stars in Praesepe
Stellar rotation periods measured from single-age populations are critical
for investigating how stellar angular momentum content evolves over time, how
that evolution depends on mass, and how rotation influences the stellar dynamo
and the magnetically heated chromosphere and corona. We report rotation periods
for 40 late-K to mid-M stars members of the nearby, rich, intermediate-age
(~600 Myr) open cluster Praesepe. These rotation periods were derived from ~200
observations taken by the Palomar Transient Factory of four cluster fields from
2010 February to May. Our measurements indicate that Praesepe's mass-period
relation transitions from a well-defined singular relation to a more scattered
distribution of both fast and slow rotators at ~0.6 Msun. The location of this
transition is broadly consistent with expectations based on observations of
younger clusters and the assumption that stellar-spin down is the dominant
mechanism influencing angular momentum evolution at 600 Myr. However, a
comparison to data recently published for the Hyades, assumed to be coeval to
Praesepe, indicates that the divergence from a singular mass-period relation
occurs at different characteristic masses, strengthening the finding that
Praesepe is the younger of the two clusters. We also use previously published
relations describing the evolution of rotation periods as a function of color
and mass to evolve the sample of Praesepe periods in time. Comparing the
resulting predictions to periods measured in M35 and NGC 2516 (~150 Myr) and
for kinematically selected young and old field star populations suggests that
stellar spin-down may progress more slowly than described by these relations.Comment: To appear in the ApJ. 18 pages, 12 figures; version with higher
resolution figures available at
http://www.astro.columbia.edu/~marcel/papers/praesepe.pdf. Paper title
inspired by local news; see http://tinyurl.com/redhone
Acceptability of Massage with Skin Barrier-enhancing Emollients in Young Neonates in Bangladesh
Oil massage of newborns has been practised for generations in the Indian sub-continent; however, oils may vary from potentially beneficial, e.g. sunflower seed oil, to potentially toxic, e.g. mustard oil. The study was carried out to gain insights into oil-massage practices and acceptability of skin barrier-enhancing emollients in young, preterm Bangladeshi neonates. Preterm infants of <33 weeks gestational age were randomized to high-linoleate sunflower seed oil, Aquaphor Original Emollient Ointmentâ„¢, or the comparison group (usual care). A survey was administered at admission to assess routine skin-care practices prior to admission and at discharge to assess acceptability of emollient therapy during hospitalization. Oil massage was given to 83 (21%) of 405 babies before hospital admission, 86% (71/83) of whom were delivered at home. Application of oil, most commonly mustard oil (88%, 73/83), was started within one hour of birth in 51 cases (61%) and was applied all over the body (89%, 74/83) one to six (mean 2.2) times before admission. Of infants who received emollient therapy in the hospital, 42% (n=32) of mothers reported that the emollient applied in the hospital was better than that available at home, and only 29% would use the same oil (i.e. mustard oil) in the future as used previously at home. No problems resulted from use of emollient in the hospital. Topical therapy with sunflower seed oil or Aquaphor was perceived by many families to be superior to mustard oil. If caregivers and health professionals can be motivated to use inexpensive, available emollients, such as sunflower seed oil that are beneficial, emollient therapy could have substantial public-health benefit
SN2010jp (PTF10aaxi): A Jet-Driven Type II Supernova
We present photometry and spectroscopy of the peculiar TypeII supernova (SN)
2010jp, also named PTF10aaxi. The light curve exhibits a linear decline with a
relatively low peak absolute magnitude of only -15.9, and a low radioactive
decay luminosity at late times that suggests a nickel mass below 0.003
. Spectra of SN2010jp display an unprecedented triple-peaked
H line profile, showing: (1) a narrow (800 km/s) central component that
suggests shock interaction with dense CSM; (2) high-velocity blue and red
emission features centered at -12600 and +15400 km/s; and (3) broad wings
extending from -22000 to +25000 km/s. These features persist during 100 days
after explosion. We propose that this line profile indicates a bipolar
jet-driven explosion, with the central component produced by normal SN ejecta
and CSM interaction at mid latitudes, while the high-velocity bumps and broad
line wings arise in a nonrelativistic bipolar jet. Two variations of the jet
interpretation seem plausible: (1) A fast jet mixes 56Ni to high velocities in
polar zones of the H-rich envelope, or (2) the reverse shock in the jet
produces blue and red bumps in Balmer lines when a jet interacts with dense
CSM. Jet-driven SNeII are predicted for collapsars resulting from a wide range
of initial masses above 25 at sub-solar metallicity. This seems
consistent with the SN host environment, which is either an extremely
low-luminosity dwarf galaxy or very remote parts of an interacting pair of
star-forming galaxies. It also seems consistent with the low 56Ni mass that may
accompany black hole formation. We speculate that the jet survives to produce
observable signatures because the star's H envelope was mostly stripped away by
previous eruptive mass loss.Comment: 11 pages, 9 figures, submitted to MNRA
High-Dose Carmustine, Etoposide, and Cyclophosphamide Followed by Allogeneic Hematopoietic Cell Transplantation for Non-Hodgkin Lymphoma
AbstractAllogeneic hematopoietic cell transplantation (HCT) has been shown to be curative in a group of patients with aggressive non-Hodgkin lymphoma (NHL). A previous study has demonstrated equivalent outcomes with a conditioning regimen based on total body irradiation and another not based on total body irradiation with preparative therapy using cyclophosphamide, carmustine, and etoposide (CBV) in autologous HCT. We investigated the safety and efficacy of using CBV in an allogeneic setting. Patients were required to have relapsed or be at high risk for subsequent relapse of NHL. All patients had a fully HLA-matched sibling donor. Patients received carmustine (15 mg/kg), etoposide (60 mg/kg), and cyclophosphamide (100 mg/kg) on days −6, −4, and −2, respectively, followed by allogeneic HCT. All patients were treated with cyclosporine and methylprednisolone as prophylaxis for graft-versus-host disease (GVHD). Thirty-one patients (median age, 46 years) who were felt to be inappropriate candidates for autologous transplantation were enrolled. Each subject had a median of 3 previous chemotherapy regimens. All patients engrafted. Fifteen of 31 patients are alive. Median follow-up time was 11.5 months (range, .4-126). There were 8 deaths due to relapse. Nonrelapse mortality (n = 8) included infection (n = 3), GVHD (n = 2), diffuse alveolar hemorrhage (n = 1), veno-occlusive disease in the setting of concurrent acute GVHD of the liver (n = 1), and leukoencephalopathy (n = 1). Probabilities of event-free survival and overall survival were, respectively, 44% (95% confidence interval, 26%-62%) and 51% (33%-69%) at 1 year and 44% (26%-62%) and 47% (29%-65%) at 5 years. Probability of relapse was 33% (15%-51%) at 1 year and 5 years. Probability of nonrelapse mortality was 31% (13%-49%) at 1 year and 5 years. Incidences were 29% for acute GVHD and 39% for chronic GVHD. None of the 12 patients who developed chronic GVHD has disease recurrence. Patients who had required >3 previous chemotherapy regimens before HCT had an increased probability of relapse. CBV is an effective preparative regimen for patients with aggressive NHL who undergo allogeneic HCT
Seminar on Evidence and Trial Practice
Outlines of speaker presentations offered during a series of one day seminars on evidence and trial practice offered by UK/CLE in late 1987-early 1988
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