137 research outputs found
Inter-relations of precipitation, aerosols, and clouds over Andalusia, southern Spain, revealed by the Andalusian Global ObseRvatory of the Atmosphere (AGORA)
The south-central interior of Andalusia experiences intricate precipitation patterns as a result of its semi-arid Mediterranean climate and the impact of Saharan dust and human-made pollutants. The primary aim of this study is to monitor the inter-relations between various factors, such as aerosols, clouds, and meteorological variables, and precipitation systems in Granada using ground-based remote sensing and in situ instruments including a microwave radiometer, ceilometer, cloud radar, nephelometer, and weather station. Over an 11-year period, we detected rain events using a physical retrieval method that employed microwave radiometer measurements. A composite analysis was applied to them to construct a climatology of the temporal evolution of precipitation. It was found that convective rain is the dominant precipitation type in Granada, accounting for 68 % of the rain events. The height of the cloud base is mainly distributed at an altitude of 2 to 7 km. Integrated water vapor (IWV) and integrated cloud liquid water (ILW) increase rapidly before the onset of rain. Aerosol scattering at the surface level and hence the aerosol concentration are reduced during rain, and the predominant mean size distribution of aerosol particles before, during, and after rain is almost the same. A meteorological environment favorable for virga formation is observed in Granada. The surface weather station detected rainfall later than the microwave radiometer, indicating virga according to ceilometer and cloud radar data. We used 889 rain-day events identified by weather station data to determine precipitation intensity classes and found that light rain is the main precipitation intensity class in Granada, accounting for 72 % of the rain-day events. This can be a result of the high tropospheric temperature induced by the Andalusian climate and the reduction of cloud droplet size by the high availability of aerosol particles in the urban atmosphere. This study provides evidence that aerosols, clouds, and meteorological variables have a combined impact on precipitation which can be considered for water resource management and improving rain forecasting accuracy.</p
Beyond the Jaynes-Cummings model: circuit QED in the ultrastrong coupling regime
In cavity quantum electrodynamics (QED), light-matter interaction is probed
at its most fundamental level, where individual atoms are coupled to single
photons stored in three-dimensional cavities. This unique possibility to
experimentally explore the foundations of quantum physics has greatly evolved
with the advent of circuit QED, where on-chip superconducting qubits and
oscillators play the roles of two-level atoms and cavities, respectively. In
the strong coupling limit, atom and cavity can exchange a photon frequently
before coherence is lost. This important regime has been reached both in cavity
and circuit QED, but the design flexibility and engineering potential of the
latter allowed for increasing the ratio between the atom-cavity coupling rate
and the cavity transition frequency above the percent level. While these
experiments are well described by the renowned Jaynes-Cummings model, novel
physics is expected in the ultrastrong coupling limit. Here, we report on the
first experimental realization of a superconducting circuit QED system in the
ultrastrong coupling limit and present direct evidence for the breakdown of the
Jaynes-Cummings model.Comment: 5 pages, 3 figure
Long-term evolution of upper stratospheric ozone at selected stations of the Network for the Detection of Stratospheric Change (NDSC)
The long-term evolution of upper stratospheric ozone has been recorded by lidars and
microwave radiometers within the ground-based Network for the Detection of
Stratospheric Change (NDSC), and by the space-borne Solar Backscatter Ultra-Violet
instruments (SBUV), Stratospheric Aerosol and Gas Experiment (SAGE), and Halogen
Occultation Experiment (HALOE). Climatological mean differences between these
instruments are typically smaller than 5% between 25 and 50 km. Ozone anomaly time
series from all instruments, averaged from 35 to 45 km altitude, track each other very
well and typically agree within 3 to 5%. SBUV seems to have a slight positive drift against
the other instruments. The corresponding 1979 to 1999 period from a transient simulation
by the fully coupled MAECHAM4-CHEM chemistry climate model reproduces many
features of the observed anomalies. However, in the upper stratosphere the model shows
too low ozone values and too negative ozone trends, probably due to an underestimation of
methane and a consequent overestimation of ClO. The combination of all observational
data sets provides a very consistent picture, with a long-term stability of 2% or better.
Upper stratospheric ozone shows three main features: (1) a decline by 10 to 15% since
1980, due to chemical destruction by chlorine; (2) two to three year fluctuations by 5 to
10%, due to the Quasi-Biennial Oscillation (QBO); (3) an 11-year oscillation by about
5%, due to the 11-year solar cycle. The 1979 to 1997 ozone trends are larger at the southern
mid-latitude station Lauder (45 S), reaching 8%/decade, compared to only about
6%/decade at Table Mountain (35 N), Haute Provence/Bordeaux ( 45 N), and
Hohenpeissenberg/Bern( 47 N). At Lauder, Hawaii (20 N), Table Mountain, and Haute
Provence, ozone residuals after subtraction of QBO- and solar cycle effects have levelled
off in recent years, or are even increasing. Assuming a turning point in January 1997,
the change of trend is largest at southern mid-latitude Lauder, +11%/decade, compared to
+7%/decade at northern mid-latitudes. This points to a beginning recovery of upper
stratospheric ozone. However, chlorine levels are still very high and ozone will remain
vulnerable. At this point the most northerly mid-latitude station, Hohenpeissenberg/Bern
differs from the other stations, and shows much less clear evidence for a beginning
recovery, with a change of trend in 1997 by only +3%/decade. In fact, record low upper
stratospheric ozone values were observed at Hohenpeissenberg/Bern, and to a lesser degree
at Table Mountain and Haute Provence, in the winters 2003/2004 and 2004/2005
Power spectrum analysis of ionospheric fluctuations with the Murchison Widefield Array
Low-frequency, wide field-of-view (FOV) radio telescopes such as the Murchison Widefield Array (MWA) enable the ionosphere to be sampled at high spatial completeness. We present the results of the first power spectrum analysis of ionospheric fluctuations in MWA data, where we examined the position offsets of radio sources appearing in two data sets. The refractive shifts in the positions of celestial sources are proportional to spatial gradients in the electron column density transverse to the line of sight. These can be used to probe plasma structures and waves in the ionosphere. The regional (10–100 km) scales probed by the MWA, determined by the size of its FOV and the spatial density of radio sources (typically thousands in a single FOV), complement the global (100–1000 km) scales of GPS studies and local (0.01–1 km) scales of radar scattering measurements. Our data exhibit a range of complex structures and waves. Some fluctuations have the characteristics of traveling ionospheric disturbances, while others take the form of narrow, slowly drifting bands aligned along the Earth's magnetic field
Anastrozole versus tamoxifen for the prevention of locoregional and contralateral breast cancer in postmenopausal women with locally excised ductal carcinoma in situ (IBIS-II DCIS): a double-blind, randomised controlled trial
Background
Third-generation aromatase inhibitors are more effective than tamoxifen for preventing recurrence in postmenopausal women with hormone-receptor-positive invasive breast cancer. However, it is not known whether anastrozole is more effective than tamoxifen for women with hormone-receptor-positive ductal carcinoma in situ (DCIS). Here, we compare the efficacy of anastrozole with that of tamoxifen in postmenopausal women with hormone-receptor-positive DCIS.
Methods
In a double-blind, multicentre, randomised placebo-controlled trial, we recruited women who had been diagnosed with locally excised, hormone-receptor-positive DCIS. Eligible women were randomly assigned in a 1:1 ratio by central computer allocation to receive 1 mg oral anastrozole or 20 mg oral tamoxifen every day for 5 years. Randomisation was stratified by major centre or hub and was done in blocks (six, eight, or ten). All trial personnel, participants, and clinicians were masked to treatment allocation and only the trial statistician had access to treatment allocation. The primary endpoint was all recurrence, including recurrent DCIS and new contralateral tumours. All analyses were done on a modified intention-to-treat basis (in all women who were randomised and did not revoke consent for their data to be included) and proportional hazard models were used to compute hazard ratios and corresponding confidence intervals. This trial is registered at the ISRCTN registry, number ISRCTN37546358.
Results
Between March 3, 2003, and Feb 8, 2012, we enrolled 2980 postmenopausal women from 236 centres in 14 countries and randomly assigned them to receive anastrozole (1449 analysed) or tamoxifen (1489 analysed). Median follow-up was 7·2 years (IQR 5·6–8·9), and 144 breast cancer recurrences were recorded. We noted no statistically significant difference in overall recurrence (67 recurrences for anastrozole vs 77 for tamoxifen; HR 0·89 [95% CI 0·64–1·23]). The non-inferiority of anastrozole was established (upper 95% CI <1·25), but its superiority to tamoxifen was not (p=0·49). A total of 69 deaths were recorded (33 for anastrozole vs 36 for tamoxifen; HR 0·93 [95% CI 0·58–1·50], p=0·78), and no specific cause was more common in one group than the other. The number of women reporting any adverse event was similar between anastrozole (1323 women, 91%) and tamoxifen (1379 women, 93%); the side-effect profiles of the two drugs differed, with more fractures, musculoskeletal events, hypercholesterolaemia, and strokes with anastrozole and more muscle spasm, gynaecological cancers and symptoms, vasomotor symptoms, and deep vein thromboses with tamoxifen.
Conclusions
No clear efficacy differences were seen between the two treatments. Anastrozole offers another treatment option for postmenopausal women with hormone-receptor-positive DCIS, which may be be more appropriate for some women with contraindications for tamoxifen. Longer follow-up will be necessary to fully evaluate treatment differences
Electron density in the F region derived from GPS/MET radio occultation data and comparison with IRI
Rac1 Regulates the NLRP3 Inflammasome Which Mediates IL-1beta Production in Chlamydophila pneumoniae Infected Human Mononuclear Cells
Chlamydophila pneumoniae causes acute respiratory tract infections and has been associated with development of asthma and atherosclerosis. The production of IL-1β, a key mediator of acute and chronic inflammation, is regulated on a transcriptional level and additionally on a posttranslational level by inflammasomes. In the present study we show that C. pneumoniae-infected human mononuclear cells produce IL-1β protein depending on an inflammasome consisting of NLRP3, the adapter protein ASC and caspase-1. We further found that the small GTPase Rac1 is activated in C. pneumoniae-infected cells. Importantly, studies with specific inhibitors as well as siRNA show that Rac1 regulates inflammasome activation in C. pneumoniae-infected cells. In conclusion, C. pneumoniae infection of mononuclear cells stimulates IL-1β production dependent on a NLRP3 inflammasome-mediated processing of proIL-1β which is controlled by Rac1
An update on ozone profile trends for the period 2000 to 2016
Ozone profile trends over the period 2000 to 2016 from several merged
satellite ozone data sets and from ground-based data measured by four
techniques at stations of the Network for the Detection of Atmospheric
Composition Change indicate significant ozone increases in the upper
stratosphere, between 35 and 48 km altitude (5 and 1 hPa).
Near 2 hPa (42 km), ozone has been increasing by about
1.5 % per decade in the tropics (20° S to 20° N),
and by 2 to 2.5 % per decade in the 35 to 60°
latitude bands of both hemispheres. At levels below 35 km
(5 hPa), 2000 to 2016 ozone trends are smaller and not statistically
significant. The observed trend profiles are consistent with expectations
from chemistry climate model simulations. This study confirms positive trends
of upper stratospheric ozone already reported, e.g., in the WMO/UNEP Ozone
Assessment 2014 or by Harris et al. (2015). Compared to those studies, three
to four additional years of observations, updated and improved data sets with
reduced drift, and the fact that nearly all individual data sets indicate
ozone increase in the upper stratosphere, all give enhanced confidence.
Uncertainties have been reduced, for example for the trend near 2 hPa
in the 35 to 60° latitude bands from about ±5 %
(2σ) in Harris et al. (2015) to less than ±2 %
(2σ). Nevertheless, a thorough analysis of possible drifts and
differences between various data sources is still required, as is a detailed
attribution of the observed increases to declining ozone-depleting substances
and to stratospheric cooling. Ongoing quality observations from multiple
independent platforms are key for verifying that recovery of the ozone layer
continues as expected
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