CoRoT, the first space-based transit search, provides ultra-high-precision light curves with continuous time-sampling over periods of up to 5 months. This allows the detection of transiting planets ...with relatively long periods, and the simultaneous study of the host star's photometric variability. In this Letter, we report the discovery of the transiting giant planet CoRoT-Exo-4b and use the CoRoT light curve to perform a detailed analysis of the transit and determine the stellar rotation period. The CoRoT light curve was pre-processed to remove outliers and correct for orbital residuals and artefacts due to hot pixels on the detector. After removing stellar variability about each transit, the transit light curve was analysed to determine the transit parameters. A discrete autocorrelation function method was used to derive the rotation period of the star from the out-of-transit light curve. We determine the periods of the planetary orbit and star's rotation of 9.20205 pm 0.00037 and 8.87 pm 1.12 days respectively, which is consistent with this being a synchronised system. We also derive the inclination, i = 90.00_{\rm-0.085} in degrees, the ratio of the orbital distance to the stellar radius, a/R_{\rm s} = 17.36_, and the planet-to-star radius ratio R_{\rm p}/R_{\rm s}=0.1047_. We discuss briefly the coincidence between the orbital period of the planet and the stellar rotation period and its possible implications for the system's migration and star-planet interaction history.
The first super-Earth with measured radius discovered was CoRoT-7b and it has opened the new field of rocky exoplanet characterisation. To better understand this interesting system, new observations ...were taken with the CoRoT satellite. During this run 90 new transits were obtained in the imagette mode. These were analysed together with the previous 151 transits obtained in the discovery run and HARPS radial velocity observations to derive accurate system parameters. A difference is found in the posterior probability distribution of the transit parameters between the previous CoRoT run (LRa01) and the new run (LRa06). We propose that this is due to an extra noise component in the previous CoRoT run suspected of being transit spot occultation events. These lead to the mean transit shape becoming V-shaped. We show that the extra noise component is dominant at low stellar flux levels and reject these transits in the final analysis. We obtained a planetary radius, Rp = 1.585 ± 0.064 R⊕ , in agreement with previous estimates. Combining the planetary radius with the new mass estimates results in a planetary density of 1.19 ± 0.27 ρ⊕ which is consistent with a rocky composition. The CoRoT-7 system remains an excellent test bed for the effects of activity in the derivation of planetary parameters in the shallow transit regime.
Noise properties of the CoRoT data Aigrain, S.; Pont, F.; Fressin, F. ...
Astronomy and astrophysics (Berlin),
10/2009, Letnik:
506, Številka:
1
Journal Article, Web Resource
Recenzirano
Odprti dostop
In this short paper, we study the photometric precision of stellar light curves obtained by the CoRoT satellite in its planet-finding channel, with a particular emphasis on the time scales ...characteristic of planetary transits. Together with other articles in the same issue of this journal, it forms an attempt to provide the building blocks for a statistical interpretation of the CoRoT planet and eclipsing binary catch to date. After pre-processing the light curves so as to minimise long-term variations and outliers, we measure the scatter of the light curves in the first three CoRoT runs lasting more than 1 month, using an iterative non-linear filter to isolate signal on the time scales of interest. The behaviour of the noise on 2 h time scales is described well by a power-law with index 0.25 in R-magnitude, ranging from 0.1 mmag at R=11.5 to 1 mmag at R=16, which is close to the pre-launch specification, though still a factor 2-3 above the photon noise due to residual jitter noise and hot pixel events. There is evidence of slight degradation in the performance over time. We find clear evidence of enhanced variability on hour time scales (at the level of 0.5 mmag) in stars identified as likely giants from their R magnitude and B-V colour, which represent approximately 60 and 20% of the observed population in the directions of Aquila and Monoceros, respectively. On the other hand, median correlated noise levels over 2 h for dwarf stars are extremely low, reaching 0.05 mmag at the bright end.
BACKGROUND/OBJECTIVES: A 29-bed long-term acute care hospital (LTCH) that cares for critically ill, but medically stable patients requiring hospitalization for 25 days or more is located in a large ...tertiary-care hospital. The patient population at LTCH is dominated by those requiring mechanical ventilation and those with debilitating illness requiring a central line for intravenous therapy. Peripherally inserted central catheters (PICC) are the preferred type of intravenous access. For as many as 40%-70% of our patients, their condition is compromised by a previously occurring infection. It is not uncommon for such debilitated patients to carry a combination of two or more resistant organisms necessitating isolation. Most patients arrive with previously inserted central lines. Nearly 75% of the patients arrive with a PICC in place. The other 25% have a PICC inserted near the time of admission. The PICC team is a contracted resource to LTCH. We do not have any control over the insertion procedure, the brand of central lines, the products used for prepping, or the initial dressing used for insertion site. These limitations truly restricted our options and forced us to use our most creative and analytic resources to determine an effective strategy to decrease our bloodstream infection (BSI) rate. After researching the products available on the market for our use, we decided to use a dressing at the insertion site that was impregnated with chlorohexidine gluconate (CHG).
METHODS: The Centers for Disease Control and Prevention (CDC) definitions for primary center venous catheter (CVC)-healthcare-associated infections (HAIs) were used. During April 2003, the staff participated in a mandatory inservice on aseptic dressing technique and proper placement of the CHG dressing within 24 hours of admission.
RESULTS: The BSI rate for January-December 2002 was 4.4/1000 CVC days. The BSI rate for January-December 2003 was 1.21/1000 CVC days, a decrease of 72.5% from previous year. The BSI rate for January-September 2004 was 1.05/100 CVC days, a decrease of 76% since project start and a 16% decrease from the previous year.
CONCLUSIONS: The implementation of CHG-impregnated dressing on the PICC site within 24 hours of admission along with the educational interventions on aseptic technique and policy changes successfully lowered the CVC-associated BSI rate in LTCH.
Noise properties of the CoRoT data Aigrain, S.; Pont, F.; Fressin, F. ...
Astronomy and astrophysics (Berlin),
10/2009, Letnik:
506, Številka:
1
Journal Article
Recenzirano
Odprti dostop
In this short paper, we study the photometric precision of stellar light curves obtained by the CoRoT satellite in its planet-finding channel, with a particular emphasis on the time scales ...characteristic of planetary transits. Together with other articles in the same issue of this journal, it forms an attempt to provide the building blocks for a statistical interpretation of the CoRoT planet and eclipsing binary catch to date. After pre-processing the light curves so as to minimise long-term variations and outliers, we measure the scatter of the light curves in the first three CoRoT runs lasting more than 1 month, using an iterative non-linear filter to isolate signal on the time scales of interest. The behaviour of the noise on 2 h time scales is described well by a power-law with index 0.25 in R-magnitude, ranging from 0.1 mmag at $R=11.5$ to 1 mmag at $R=16$, which is close to the pre-launch specification, though still a factor 2-3 above the photon noise due to residual jitter noise and hot pixel events. There is evidence of slight degradation in the performance over time. We find clear evidence of enhanced variability on hour time scales (at the level of 0.5 mmag) in stars identified as likely giants from their R magnitude and $B-V$ colour, which represent approximately 60 and 20% of the observed population in the directions of Aquila and Monoceros, respectively. On the other hand, median correlated noise levels over 2 h for dwarf stars are extremely low, reaching 0.05 mmag at the bright end.
CoRoT, the first space-based transit search, provides ultra-high-precision light curves with continuous time-sampling over periods of up to 5 months. This allows the detection of transiting planets ...with relatively long periods, and the simultaneous study of the host star's photometric variability. In this Letter, we report the discovery of the transiting giant planet CoRoT-Exo-4b and use the CoRoT light curve to perform a detailed analysis of the transit and determine the stellar rotation period. The CoRoT light curve was pre-processed to remove outliers and correct for orbital residuals and artefacts due to hot pixels on the detector. After removing stellar variability about each transit, the transit light curve was analysed to determine the transit parameters. A discrete autocorrelation function method was used to derive the rotation period of the star from the out-of-transit light curve. We determine the periods of the planetary orbit and star's rotation of 9.20205 ± 0.00037 and 8.87 ± 1.12 days respectively, which is consistent with this being a synchronised system. We also derive the inclination, $i = 90.00_{\rm -0.085}^{+0.000}$ in degrees, the ratio of the orbital distance to the stellar radius, $a/R_{\rm s} = 17.36_{-0.25}^{+0.05}$, and the planet-to-star radius ratio $R_{\rm p}/R_{\rm s}=0.1047_{-0.0022}^{+0.0041}$. We discuss briefly the coincidence between the orbital period of the planet and the stellar rotation period and its possible implications for the system's migration and star-planet interaction history.
CoRoT, the first space-based transit search, provides ultra-high precision light curves with continuous time-sampling over periods, of up to 5 months. This allows the detection of transiting planets ...with relatively long periods, and the simultaneous study of the host star's photometric variability. In this letter, we report on the discovery of the transiting giant planet CoRoT-Exo-4b and use the CoRoT light curve to perform a detailed analysis of the transit and to determine the stellar rotation period. The CoRoT light curve was pre-processed to remove outliers and correct for orbital residuals and artefacts due to hot pixels on the detector. After removing stellar variability around each transit, the transit light curve was analysed to determine the transit parameters. A discrete auto-correlation function method was used to derive the rotation period of the star from the out-of-transit light curve. We derive periods for the planet's orbit and star's rotation of 9.20205 +/- 0.00037 and 8.87 +/- 1.12 days respectively, consistent with a synchronised system. We also derive the inclination, i = 90.00 -0.085 +0.000 in degrees, the ratio of the orbital distance to the stellar radius, a/R_s = 17.36 -0.25 +0.05, and the planet to star radius ratio R_p/R_s = 0.1047 -0.0022 +0.0041. We discuss briefly the coincidence between the orbital period of the planet and the stellar rotation period and its possible implications for the system's migration and star-planet interaction history.
Autologous haematopoietic SCT with PBSCs is regularly used to restore BM function in patients with multiple myeloma or lymphoma after myeloablative chemotherapy. Twenty-eight experts from the ...European Group for Blood and Marrow Transplantation developed a position statement on the best approaches to mobilising PBSCs and on possibilities of optimising graft yields in patients who mobilise poorly. Choosing the appropriate mobilisation regimen, based on patients' disease stage and condition, and optimising the apheresis protocol can improve mobilisation outcomes. Several factors may influence mobilisation outcomes, including older age, a more advanced disease stage, the type of prior chemotherapy (e.g., fludarabine or melphalan), prior irradiation or a higher number of prior treatment lines. The most robust predictive factor for poor PBSC collection is the CD34(+) cell count in PB before apheresis. Determination of the CD34(+) cell count in PB before apheresis helps to identify patients at risk of poor PBSC collection and allows pre-emptive intervention to rescue mobilisation in these patients. Such a proactive approach might help to overcome deficiencies in stem cell mobilisation and offers a rationale for the use of novel mobilisation agents.
Mesenchymal stromal cells (MSCs) are promising cell therapy candidates. Clinical application is considered safe. However, minor side effects have included thromboembolism and instant blood-mediated ...inflammatory reactions suggesting an effect of MSC infusion on hemostasis. Previous studies focusing on plasmatic coagulation as a secondary hemostasis step detected both procoagulatory and anticoagulatory activities of MSCs. We now focus on primary hemostasis and analyzed whether MSCs can promote or inhibit platelet activation.
Effects of MSCs and MSC supernatant on platelet activation and function were studied using flow cytometry and further platelet function analyses. MSCs from bone marrow (BM), lipoaspirate (LA) and cord blood (CB) were compared to human umbilical vein endothelial cells or HeLa tumor cells as inhibitory or activating cells, respectively.
BM-MSCs and LA-MSCs inhibited activation and aggregation of stimulated platelets independent of the agonist used. This inhibitory effect was confirmed in diagnostic point-of-care platelet function analyses in platelet-rich plasma and whole blood. Using inhibitors of the CD39-CD73-adenosine axis, we showed that adenosine produced by CD73 ectonucleotidase activity was largely responsible for the LA-MSC and BM-MSC platelet inhibitory action. With CB-MSCs, batch-dependent responses were obvious, with some batches exerting inhibition and others lacking this effect.
Studies focusing on plasmatic coagulation suggested both procoagulatory and anticoagulatory activities of MSCs. We now show that MSCs can, dependent on their tissue origin, inhibit platelet activation involving adenosine converted from adenosine monophosphate by CD73 ectonucleotidase activity. These data may have strong implications for safety and risk/benefit assessment regarding MSCs from different tissue sources and may help to explain the tissue protective mode of action of MSCs. The adenosinergic pathway emerges as a key mechanism by which MSCs exert hemostatic and immunomodulatory functions.
Climate exerted constraints on the growth and decline of past human societies but our knowledge of temporal and spatial climatic patterns is often too restricted to address causal connections. At a ...global scale, the inter-hemispheric thermal balance provides an emergent framework for understanding regional Holocene climate variability. As the thermal balance adjusted to gradual changes in the seasonality of insolation, the Intertropical Convergence Zone migrated southward accompanied by a weakening of the Indian summer monsoon. Superimposed on this trend, anomalies such as the Little Ice Age point to asymmetric changes in the extratropics of either hemisphere. Here we present a reconstruction of the Indian winter monsoon in the Arabian Sea for the last 6000 years based on paleobiological records in sediments from the continental margin of Pakistan at two levels of ecological complexity: sedimentary ancient DNA reflecting water column environmental states and planktonic foraminifers sensitive to winter conditions. We show that strong winter monsoons between ca. 4500 and 3000 years ago occurred during a period characterized by a series of weak interhemispheric temperature contrast intervals, which we identify as the early neoglacial anomalies (ENA). The strong winter monsoons during ENA were accompanied by changes in wind and precipitation patterns that are particularly evident across the eastern Northern Hemisphere and tropics. This coordinated climate reorganization may have helped trigger the metamorphosis of the urban Harappan civilization into a rural society through a push–pull migration from summer flood-deficient river valleys to the Himalayan piedmont plains with augmented winter rains. The decline in the winter monsoon between 3300 and 3000 years ago at the end of ENA could have played a role in the demise of the rural late Harappans during that time as the first Iron Age culture established itself on the Ghaggar-Hakra interfluve. Finally, we speculate that time-transgressive land cover changes due to aridification of the tropics may have led to a generalized instability of the global climate during ENA at the transition from the warmer Holocene thermal maximum to the cooler Neoglacial.
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