8,909 research outputs found
Discovery of Microsecond Soft Lags in the X-Ray Emission of the Atoll Source 4U1636-536
Exploiting the presence of kilohertz quasi-periodic oscillations (QPOs) in
the timing power spectrum, we find that the soft x-ray emission of the
neutron-star X-ray binary and atoll source 4U1636-536 modulated at the QPO
frequency lags behind that of the hard x-ray emission. Emission in the 3.8-6.4
keV band is delayed by 25.0 +/- 3.3 microseconds relative to the 9.3-69 keV
band. The delay increases in magnitude with increasing energy. Our results are
consistent with those of Vaughan et al. (1997), when the sign is corrected
(Vaughan et al. 1998), for the atoll source 4U1608-52. The soft lag could be
produced by Comptonization of hard photons injected into a cooler electron
cloud or by intrinsic spectral softening of the emission during each
oscillation cycle.Comment: Accepted to the Astrophysical Journal Letters, 4 page
Host-pathogen reorganisation during host cell entry by Chlamydia trachomatis
Chlamydia trachomatis is obligate intracellular bacterial pathogen that remains a significant public health burden worldwide. A critical early event during infection is chlamydial entry into non-phagocytic host epithelial cells. Like other Gram-negative bacteria, C. trachomatis uses a type III secretion system (T3SS) to deliver virulence effector proteins into host cells. These effectors trigger bacterial uptake and promote bacterial survival and replication within the host cell. In this review, we highlight recent cryo-electron tomography that has provided striking insights into the initial interactions between Chlamydia and its host. We describe the polarised structure of extracellular C. trachomatis elementary bodies (EBs), and the supramolecular organisation of T3SS complexes on the EB surface, in addition to the changes in host and pathogen architecture that accompany bacterial internalisation and EB encapsulation into early intracellular vacuoles. Finally, we consider the implications for further understanding the mechanism of C. trachomatis entry and how this might relate to those of other bacteria and viruses
New emissive mononuclear copper (I) complex: Structural and photophysical characterization focusing on solvatochromism, rigidochromism and oxygen sensing in mesoporous solid matrix
Transit Timing Observations from Kepler: VII. Confirmation of 27 planets in 13 multiplanet systems via Transit Timing Variations and orbital stability
We confirm 27 planets in 13 planetary systems by showing the existence of
statistically significant anti-correlated transit timing variations (TTVs),
which demonstrates that the planet candidates are in the same system, and
long-term dynamical stability, which places limits on the masses of the
candidates---showing that they are planetary. %This overall method of planet
confirmation was first applied to \kepler systems 23 through 32. All of these
newly confirmed planetary systems have orbital periods that place them near
first-order mean motion resonances (MMRs), including 6 systems near the 2:1
MMR, 5 near 3:2, and one each near 4:3, 5:4, and 6:5. In addition, several
unconfirmed planet candidates exist in some systems (that cannot be confirmed
with this method at this time). A few of these candidates would also be near
first order MMRs with either the confirmed planets or with other candidates.
One system of particular interest, Kepler-56 (KOI-1241), is a pair of planets
orbiting a 12th magnitude, giant star with radius over three times that of the
Sun and effective temperature of 4900 K---among the largest stars known to host
a transiting exoplanetary system.Comment: 12 pages, 13 figures, 5 tables. Submitted to MNRA
Early College, Early Success: Early College High School Initiative Impact Study
In 2002, the Bill & Melinda Gates Foundation launched the ECHSI with the primary goal of increasing the opportunity for underserved students to earn a postsecondary credential. To achieve this goal, Early Colleges provide underserved students with exposure to, and support in, college while they are in high school. Early Colleges partner with colleges and universities to offer all students an opportunity to earn an associate's degree or up to two years of college credits toward a bachelor's degree during high school at no or low cost to the students. The underlying assumption is that engaging underrepresented students in a rigorous high school curriculum tied to the incentive of earning college credit will motivate them and increase their access to additional postsecondary education and credentials after high school. Since 2002, more than 240 Early Colleges have opened nationwideThis study focused on the impact of Early Colleges. It addressed two questions:1. Do Early College students have better outcomes than they would have had at other high schools?2. Does the impact of Early Colleges vary by student background characteristics (e.g., gender and family income)? To answer these questions, we conducted a lottery-based randomized experiment, taking advantage of the fact that some Early Colleges used lotteries in their admissions processes. By comparing the outcomes for students who participated in admissions lotteries and were offered enrollment with the outcomes for students who participated in the lotteries but were not offered enrollment, we can draw causal conclusions about the impact of Early Colleges.The primary student outcomes for this study were high school graduation, college enrollment, and college degree attainment. We also examined students' high school and college experiences. Data on student background characteristics and high school outcomes came from administrative records from schools, districts, and states; data on collegeoutcomes came from the National Student Clearinghouse (NSC); and data on high school and college experiences and intermediate outcomes such as college credit accrual camefrom a student surveyWe assessed the impact of Early Colleges on these outcomes for a sample of 10 Early Colleges that did the following:-Enrolled students in grades 9 -- 12 and had high school graduates in the study years (2005 -- 2011)-Used lotteries as part of the admission processes in at least one of the study cohorts (students who entered ninth grade in 2005 -- 06, 2006 -- 07, or 2007 -- 08)-Retained the lottery recordsEight of the 10 Early Colleges in the study were included in the student survey. The overall study sample included 2,458 students and the survey sample included 1,294 students. The study extended through three years past high school
Running Inflation in the Standard Model
An interacting scalar field with largish coupling to curvature can support a
distinctive inflationary universe scenario. Previously this has been discussed
for the Standard Model Higgs field, treated classically or in a leading log
approximation. Here we investigate the quantum theory using renormalization
group methods. In this model the running of both the effective Planck mass and
the couplings is important. The cosmological predictions are consistent with
existing WMAP5 data, with 0.967 < n_s < 0.98 (for N_e = 60) and negligible
gravity waves. We find a relationship between the spectral index and the Higgs
mass that is sharply varying for m_h ~ 120-135 GeV (depending on the top mass);
in the future, that relationship could be tested against data from PLANCK and
LHC. We also comment briefly on how similar dynamics might arise in more
general settings, and discuss our assumptions from the effective field theory
point of view.Comment: 17 pages in Phys Lett B format, 5 figures; v3: updated to match
published version, includes new Appendix B on EF
Cabazitaxel in platinum pre-treated patients with locally advanced or metastatic transitional cell carcinoma who developed disease progression after platinum based chemotherapy : results of the phase II CAB-B1 trial
There is a paucity of chemotherapy options for patients with urothelial cancers who have relapsed following platinum based chemotherapy (CT).
CAB-B1 was a single centre phase II randomised controlled trial of Cabazitaxel (CAB; 25mg/m2 q3 week for 6 cycles) versus
best supportive care (BSC) in patients with histologically proven transitional cell carcinoma (TCC), locally advanced or
metastatic, who had recurred after receiving platinum based treatment. Primary outcome was overall response rate (ORR)
using RESIST. Secondary outcomes included Progression Free Survival (PFS) and Overall Survival (OS).
Between January 2013 and October 2016, 20 patients were randomised (10 on each arm). BSC included paclitaxel CT for 9
patients and radiotherapy for 1 patient. 8 patients completed 6 cycles of CT (3 on CAB; 5 on BSC). 2 patients had an ORR
on CAB and 1 patient on BSC. Median OS was 5.8 months (95% confidence interval (CI) 0.7-14.6) for CAB patients and
7.5 months (95% CI 1.0-10.8) for BSC patients. Median PFS was 4.8 months (95% CI 0.7-8.3) for CAB patients and 3.7
months (95% CI 1.0-7.0) for BSC patients.
CAB-B1 successfully reached the efficacy target for 1st stage, showing that there could be a role for CAB in these patients
CLASH: Weak-Lensing Shear-and-Magnification Analysis of 20 Galaxy Clusters
We present a joint shear-and-magnification weak-lensing analysis of a sample
of 16 X-ray-regular and 4 high-magnification galaxy clusters at 0.19<z<0.69
selected from the Cluster Lensing And Supernova survey with Hubble (CLASH). Our
analysis uses wide-field multi-color imaging, taken primarily with Suprime-Cam
on the Subaru Telescope. From a stacked shear-only analysis of the
X-ray-selected subsample, we detect the ensemble-averaged lensing signal with a
total signal-to-noise ratio of ~25 in the radial range of 200 to 3500kpc/h. The
stacked tangential-shear signal is well described by a family of standard
density profiles predicted for dark-matter-dominated halos in gravitational
equilibrium, namely the Navarro-Frenk-White (NFW), truncated variants of NFW,
and Einasto models. For the NFW model, we measure a mean concentration of
at . We show this is in excellent agreement with Lambda
cold-dark-matter (LCDM) predictions when the CLASH X-ray selection function and
projection effects are taken into account. The best-fit Einasto shape parameter
is , which is consistent with the
NFW-equivalent Einasto parameter of . We reconstruct projected mass
density profiles of all CLASH clusters from a joint likelihood analysis of
shear-and-magnification data, and measure cluster masses at several
characteristic radii. We also derive an ensemble-averaged total projected mass
profile of the X-ray-selected subsample by stacking their individual mass
profiles. The stacked total mass profile, constrained by the
shear+magnification data, is shown to be consistent with our shear-based
halo-model predictions including the effects of surrounding large-scale
structure as a two-halo term, establishing further consistency in the context
of the LCDM model.Comment: Accepted by ApJ on 11 August 2014. Textual changes to improve clarity
(e.g., Sec.3.2.2 "Number-count Depletion", Sec.4.3 "Shape Measurement",
Sec.4.4 "Background Galaxy Selection"). Results and conclusions remain
unchanged. For the public release of Subaru data, see
http://archive.stsci.edu/prepds/clash
Does the revised cardiac risk index predict cardiac complications following elective lung resection?
Background:
Revised Cardiac Risk Index (RCRI) score and Thoracic Revised Cardiac Risk Index (ThRCRI) score were developed to predict the risks of postoperative major cardiac complications in generic surgical population and thoracic surgery respectively. This study aims to determine the accuracy of these scores in predicting the risk of developing cardiac complications including atrial arrhythmias after lung resection surgery in adults.
Methods:
We studied 703 patients undergoing lung resection surgery in a tertiary thoracic surgery centre. Observed outcome measures of postoperative cardiac morbidity and mortality were compared against those predicted by risk.
Results:
Postoperative major cardiac complications and supraventricular arrhythmias occurred in 4.8% of patients. Both index scores had poor discriminative ability for predicting postoperative cardiac complications with an area under receiver operating characteristic (ROC) curve of 0.59 (95% CI 0.51-0.67) for the RCRI score and 0.57 (95% CI 0.49-0.66) for the ThRCRI score.
Conclusions:
In our cohort, RCRI and ThRCRI scores failed to accurately predict the risk of cardiac complications in patients undergoing elective resection of lung cancer. The British Thoracic Society (BTS) recommendation to seek a cardiology referral for all asymptomatic pre-operative lung resection patients with > 3 RCRI risk factors is thus unlikely to be of clinical benefit
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