1,502 research outputs found
KMT-2022-BLG-2397: Brown Dwarf at the Upper Shore of the Einstein Desert
We measure the Einstein radius of the single-lens microlensing event
KMT-2022-BLG-2397 to be theta_E=24.8 +- 3.6 uas, placing it at the upper shore
of the Einstein Desert, 9 < theta_E / uas < 25, between free-floating planets
(FFPs) and bulge brown dwarfs (BDs). In contrast to the six BD (25 < theta_E <
50) events presented by Gould+22, which all had giant-star source stars,
KMT-2022-BLG-2397 has a dwarf-star source, with angular radius theta_* ~ 0.9
uas. This prompts us to study the relative utility of dwarf and giant sources
for characterizing FFPs and BDs from finite-source point-lens (FSPL)
microlensing events. We find `dwarfs' (including main-sequence stars and
subgiants) are likely to yield twice as many theta_E measurements for BDs and a
comparable (but more difficult to quantify) improvement for FFPs. We show that
neither current nor planned experiments will yield complete mass measurements
of isolated bulge BDs, nor will any other planned experiment yield as many
theta_E measurements for these objects as KMT. Thus, the currently anticipated
10-year KMT survey will remain the best way to study bulge BDs for several
decades to come.Comment: 45 pages, 9 Figures, submitted to AAS Journal
KMT-2021-BLG-1122L: The first microlensing triple stellar system
We systematically inspect the microlensing data acquired by the KMTNet survey
during the previous seasons in order to find anomalous lensing events for which
the anomalies in the lensing light curves cannot be explained by the usual
binary-lens or binary-source interpretations. From the inspection, we find that
interpreting the three lensing events OGLE-2018-BLG-0584, KMT-2018-BLG-2119,
and KMT-2021-BLG-1122 requires four-body (lens+source) models, in which either
both the lens and source are binaries (2L2S event) or the lens is a triple
system (3L1S event). Following the analyses of the 2L2S events presented in
\citet{Han2023}, here we present the 3L1S analysis of the KMT-2021-BLG-1122. It
is found that the lens of the event KMT-2021-BLG-1122 is composed of three
masses, in which the projected separations (normalized to the angular Einstein
radius) and mass ratios between the lens companions and the primary are and . By conducting a
Bayesian analysis, we estimate that the masses of the individual lens
components are . The companions are separated in projection from the primary by
~AU. The lens of KMT-2018-BLG-2119
is the first triple stellar system detected via microlensing.Comment: 8 pages, 7 figures, 2 table
Macrolide resistance and genotypic characterization of Streptococcus pneumoniae in Asian countries: a study of the Asian Network for Surveillance of Resistant Pathogens (ANSORP)
Objectives: To characterize mechanisms of macrolide resistance among Streptococcus pneumoniae from 10 Asian countries during 1998-2001. Methods: Phenotypic and genotypic characterization of the isolates and their resistance mechanisms. Results: Of 555 isolates studied, 216 (38.9%) were susceptible, 10 (1.8%) were intermediate and 329 (59.3%) were resistant to erythromycin. Vietnam had the highest prevalence of erythromycin resistance (88.3%), followed by Taiwan (87.2%), Korea (85.1%), Hong Kong (76.5%) and China (75.6%). Ribosomal methylation encoded by erm(B) was the most common mechanism of erythromycin resistance in China, Taiwan, Sri Lanka and Korea. In Hong Kong, Singapore, Thailand and Malaysia, efflux encoded by mef(A) was the more common in erythromycin-resistant isolates. In most Asian countries except Hong Kong, Malaysia and Singapore, erm(B) was found in >50% of pneumococcal isolates either alone or in combination with mef(A). The level of erythromycin resistance among pneumococcal isolates in most Asian countries except Thailand and India was very high with MIC90s of >128 mg/L. Molecular epidemiological studies suggest the horizontal transfer of the erm(B) gene and clonal dissemination of resistant strains in the Asian region. Conclusion: Data confirm that macrolide resistance in pneumococci is a serious problem in many Asian countries
Mass Production of 2021 KMTNet Microlensing Planets II
We continue our program of publishing all planets (and possible planets)
found by eye in 2021 Korea Microlensing Telescope Network (KMTNet) online data.
We present 4 planets, (KMT-2021-BLG-0712Lb, KMT-2021-BLG-0909Lb,
KMT-2021-BLG-2478Lb, and KMT-2021-BLG-1105Lb), with planet-host mass ratios in
the range -3.3 < log q < -2.2. This brings the total of secure, by-eye, 2021
KMTNet planets to 16, including 8 in this series. The by-eye sample is an
important check of the completeness of semi-automated detections, which are the
basis for statistical analyses. One of the planets, KMT-2021-BLG-1105Lb, is
blended with a relatively bright star that may be the
host. This could be verified immediately by high-resolution imaging. If so, the
host is an early G dwarf, and the planet could be characterized by
radial-velocity observations on 30m class telescopes
Discriminating lymphomas and reactive lymphadenopathy in lymph node biopsies by gene expression profiling
<p>Abstract</p> <p>Background</p> <p>Diagnostic accuracy of lymphoma, a heterogeneous cancer, is essential for patient management. Several ancillary tests including immunophenotyping, and sometimes cytogenetics and PCR are required to aid histological diagnosis. In this proof of principle study, gene expression microarray was evaluated as a single platform test in the differential diagnosis of common lymphoma subtypes and reactive lymphadenopathy (RL) in lymph node biopsies.</p> <p>Methods</p> <p>116 lymph node biopsies diagnosed as RL, classical Hodgkin lymphoma (cHL), diffuse large B cell lymphoma (DLBCL) or follicular lymphoma (FL) were assayed by mRNA microarray. Three supervised classification strategies (global multi-class, local binary-class and global binary-class classifications) using diagonal linear discriminant analysis was performed on training sets of array data and the classification error rates calculated by leave one out cross-validation. The independent error rate was then evaluated by testing the identified gene classifiers on an independent (test) set of array data.</p> <p>Results</p> <p>The binary classifications provided prediction accuracies, between a subtype of interest and the remaining samples, of 88.5%, 82.8%, 82.8% and 80.0% for FL, cHL, DLBCL, and RL respectively. Identified gene classifiers include LIM domain only-2 (<it>LMO2</it>), Chemokine (C-C motif) ligand 22 (<it>CCL22</it>) and Cyclin-dependent kinase inhibitor-3 (<it>CDK3</it>) specifically for FL, cHL and DLBCL subtypes respectively.</p> <p>Conclusions</p> <p>This study highlights the ability of gene expression profiling to distinguish lymphoma from reactive conditions and classify the major subtypes of lymphoma in a diagnostic setting. A cost-effective single platform "mini-chip" assay could, in principle, be developed to aid the quick diagnosis of lymph node biopsies with the potential to incorporate other pathological entities into such an assay.</p
KMT-2021-BLG-2010Lb, KMT-2022-BLG-0371Lb, and KMT-2022-BLG-1013Lb: Three microlensing planets detected via partially covered signals
We inspect 4 microlensing events KMT-2021-BLG-1968, KMT-2021-BLG-2010,
KMT-2022-BLG-0371, and KMT-2022-BLG-1013, for which the light curves exhibit
partially covered short-term central anomalies. We conduct detailed analyses of
the events with the aim of revealing the nature of the anomalies. We test
various models that can give rise to the anomalies of the individual events
including the binary-lens (2L1S) and binary-source (1L2S) interpretations.
Under the 2L1S interpretation, we thoroughly inspect the parameter space to
check the existence of degenerate solutions, and if they exist, we test the
feasibility of resolving the degeneracy. We find that the anomalies in
KMT-2021-BLG-2010 and KMT-2022-BLG-1013 are uniquely defined by planetary-lens
interpretations with the planet-to-host mass ratios of and , respectively. For KMT-2022-BLG-0371, a
planetary solution with a mass ratio is strongly
favored over the other three degenerate 2L1S solutions with different mass
ratios based on the and relative proper motion arguments, and a 1L2S
solution is clearly ruled out. For KMT-2021-BLG-1968, on the other hand, we
find that the anomaly can be explained either by a planetary or a binary-source
interpretation, making it difficult to firmly identify the nature of the
anomaly. From the Bayesian analyses of the identified planetary events, we
estimate that the masses of the planet and host are ,
, and for KMT-2021-BLG-2010L, KMT-2022-BLG-0371L, and
KMT-2022-BLG-1013L, respectively.Comment: 12 pages, 17 figure
Systematic KMTNet Planetary Anomaly Search. IV. Complete Statistical Sample of 2019 Prime-Field Microlensing Planets
We report the complete statistical planetary sample from the prime fields
() of the 2019 Korea Microlensing Telescope
Network (KMTNet) microlensing survey. We develop the optimized KMTNet
AnomalyFinder algorithm and apply it to the 2019 KMTNet prime fields. We find a
total of 14 homogeneously selected planets and report the analysis of three
planetary events, KMT-2019-BLG-(1042,1552,2974). The planet-host mass ratios,
, for the three planetary events are and , respectively. A Bayesian analysis indicates
the three planets are all cold giant planets beyond the snow line of their host
stars. The 14 planets are basically uniform in over the range . This result suggests that the planets below proposed by the MOA-II survey may be more common than
previously believed. This work is an early component of a large project to
determine the KMTNet mass-ratio function, and the whole sample of 2016--2019
KMTNet events should contain about 120 planets.Comment: 7 figures and 7 tables; submitte
Systematic KMTNet Planetary Anomaly Search. X. Complete Sample of 2017 Prime-Field Planets
We complete the analysis of planetary candidates found by the KMT
AnomalyFinder for the 2017 prime fields that cover . We
report 3 unambiguous planets: OGLE-2017-BLG-0640, OGLE-2017-BLG-1275, and
OGLE-2017-BLG-1237. The first two of these were not previously identified,
while the last was not previously published due to technical complications
induced by a nearby variable. We further report that a fourth anomalous event,
the previously recognized OGLE-2017-BLG-1777, is very likely to be planetary,
although its light curve requires unusually complex modeling because the lens
and source both have orbiting companions. One of the 3 unambiguous planets,
OGLE-2017-BLG-1275 is the first AnomalyFinder discovery that has a {\it
Spitzer} microlens parallax measurement, , implying
that this planetary system almost certainly lies in the Galactic bulge. In the
order listed, the four planetary events have planet-host mass ratios , and
normalized projected separations , of = ,
, , and . Combined with
previously published events, the 2017 AnomalyFinder prime fields contain 11
unambiguous planets with well-measured and one very likely candidate, of
which 3 are AnomalyFinder discoveries. In addition to these 12, there are three
other unambiguous planets with large uncertainties in .Comment: 67 pages, 13 figures, 16 table
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