Reconciling aerosol light extinction measurements from spaceborne lidar observations and in situ measurements in the Arctic

© Author(s) 2014. This work is distributed under the Creative Commons Attribution 3.0 License.In this study we investigate to what degree it is possible to reconcile continuously recorded particle light extinction coefficients derived from dry in situ measurements at Zeppelin station (78.92° N, 11.85° E; 475 m above sea level), Ny-Ålesund, Svalbard, that are recalculated to ambient relative humidity, as well as simultaneous ambient observations with the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. To our knowledge, this represents the first study that compares spaceborne lidar measurements to optical aerosol properties from short-term in situ observations (averaged over 5 h) on a case-by-case basis. Finding suitable comparison cases requires an elaborate screening and matching of the CALIOP data with respect to the location of Zeppelin station as well as the selection of temporal and spatial averaging intervals for both the ground-based and spaceborne observations. Reliable reconciliation of these data cannot be achieved with the closest-approach method, which is often used in matching CALIOP observations to those taken at ground sites. This is due to the transport pathways of the air parcels that were sampled. The use of trajectories allowed us to establish a connection between spaceborne and ground-based observations for 57 individual overpasses out of a total of 2018 that occurred in our region of interest around Svalbard (0 to 25° E, 75 to 82° N) in the considered year of 2008. Matches could only be established during winter and spring, since the low aerosol load during summer in connection with the strong solar background and the high occurrence rate of clouds strongly influences the performance and reliability of CALIOP observations. Extinction coefficients in the range of 2 to 130 Mmg-1 at 532 nm were found for successful matches with a difference of a factor of 1.47 (median value for a range from 0.26 to 11.2) between the findings of in situ and spaceborne observations (the latter being generally larger than the former). The remaining difference is likely to be due to the natural variability in aerosol concentration and ambient relative humidity, an insufficient representation of aerosol particle growth, or a misclassification of aerosol type (i.e., choice of lidar ratio) in the CALIPSO retrieval.Peer reviewe

Newspaper Coverage of the 2008 General Election Presidential Campaigns

News coverage of political campaigns is very important to the political campaign process. Some voters pay little attention to debates or other sources of information about the candidates and their policies. The news is one important source of this information. Newspapers can also supplement and reinforce the information possessed by voters who do attend to campaign messages. This study content analyzed news coverage of the 2008 general election presidential campaign (New York Times, Washington Post, USA Today). Horse race coverage was most common topic (45%), followed by themes about character (32%), and policy (23%). The tone of newspaper coverage was more positive (51%) than negative (39%; 9% of themes reported the candidates‘ defenses)

Detection of cancer cells in the cerebrospinal fluid: current methods and future directions

The spread of cancer into the central nervous system is a serious problem leading to neurological symptoms and rapid mortality. The current tools available for detecting the spread of cancer into the cerebrospinal fluid (CSF) are cytology, neurologic examination, and neuroimaging. All three of these methods can be applied in concert to reach a diagnosis, but they all suffer from a lack of sensitivity, leading to delays in treatment in many cases. An overview of research tools in the field of CSF cancer detection reveals a variety of promising technologies that can be used to answer questions about the biology of metastatic cancer and to develop more powerful clinical detection methods. Methods currently under investigation include new immunocytochemistry methods and flow cytometry for the in vitro detection of cells. Additionally, polymerase chain reaction, fluorescence in situ hybridization, capillary electrophoresis with laser-induced fluorescence, and mass spectrometry using matrix-assisted laser absorption-deionization time-of-flight and surface-enhanced laser desorption/ionization time-of-flight techniques are being tested for in vitro assessment of the non-cellular biomarkers in CSF. For in vivo detection of cancer in the CSF, research techniques include certain quantum dot platforms as well as magnetic iron oxide nanoparticles. As systemic therapies for cancer improve, the CNS is becoming a more common site of disease recurrence. This increases the importance of effective detection methods in the CSF, since early intervention can maximize therapeutic benefit. Furthermore, many cell-based detection methods can be combined with therapeutic agents to serve multiple medical functions through a common targeting system

Single particle analysis of ice crystal residuals observed in orographic wave clouds over Scandinavia during INTACC experiment

International audienceIndividual ice crystal residual particles collected over Scandinavia during the INTACC (INTeraction of Aerosol and Cold Clouds) experiment in October 1999 were analyzed by Scanning Electron Microscopy (SEM) equipped with Energy-Dispersive X-ray Analysis (EDX). Samples were collected onboard the British Met Office Hercules C-130 aircraft using a Counterflow Virtual Impactor (CVI). This study is based on six samples collected in orographic clouds. The main aim of this study is to characterize cloud residual elemental composition in conditions affected by different airmasses. In total 609 particles larger than 0.1 ?m diameter were analyzed and their elemental composition and morphology were determined. Thereafter a hierarchical cluster analysis was performed on the signal detected with SEM-EDX in order to identify the major particle classes and their abundance. A cluster containing mineral dust, represented by aluminosilicates, Fe-rich and Si-rich particles, was the dominating class of particles, accounting for about 57.5% of the particles analyzed, followed by low-Z particles, 23.3% (presumably organic material) and sea salt (6.7%). Sulfur was detected often across all groups, indicating ageing and in-cloud processing of particles. A detailed inspection of samples individually unveiled a relationship between ice crystal residual composition and airmass origin. Cloud residual samples from clean airmasses (that is, trajectories confined to the Atlantic and Arctic Oceans and/or with source altitude in the free troposphere) were dominated primarily by low-Z and sea salt particles, while continentally-influenced airmasses (with trajectories that originated or traveled over continental areas and with source altitude in the continental boundary layer) contained mainly mineral dust residuals. Comparison of residual composition for similar cloud ambient temperatures around ?27°C revealed that supercooled clouds are more likely to persist in conditions where low-Z particles represent significant part of the analyzed cloud residual particles. This indicates that organic material may be poor ice nuclei, in contrast to polluted cases when ice crystal formation was observed at the same environmental conditions and when the cloud residual composition was dominated by mineral dust. The presented results suggest that the chemical composition of cloud nuclei and airmass origin have a strong impact on the ice formation through heterogeneous nucleation in supercooled clouds

Exposure to smoking in movies among British adolescents 2001–2006

ObjectiveTo estimate youth exposure to smoking in movies in the UK and compare the likely effect with the USA.MethodsWe collected tobacco occurrences data for 572 top-grossing films in the UK screened from 2001 to 2006 and estimated the number of on-screen tobacco impressions delivered to British youths in this time period.Results91% of films in our sample that contained smoking were youth-rated films (British Board of Film Classification rating '15' and lower), delivering at least 1.10 billion tobacco impressions to British youths during theatrical release. British youths were exposed to 28% more smoking impressions in UK youth-rated movies than American youth-rated movies, because 79% of movies rated for adults in the USA ('R') are classified as suitable for youths in the UK ('15' or '12A').ConclusionBecause there is a dose-response relation between the amount of on-screen exposure to smoking and the likelihood that adolescents will begin smoking, the fact that there is substantially higher exposure to smoking in youth-rated films in the UK than in the USA suggests that the fraction of all youth smoking because of films in the UK is probably larger than in the USA. Other countries with ratings systems that are less conservative (in terms of language and sexuality) than the USA will also be likely to deliver more on-screen tobacco impressions to youths. Assigning an '18' classification to movies that contain smoking would substantially reduce youth exposure to on-screen smoking and, hence, smoking initiation among British youths

News Coverage of the 2008 Presidential Primaries

President George W. Bush was completing his second (and final) term in office and Vice President Dick Cheney decided not to run for president. Thus, the 2008 American presidential primary is the first “open” campaign (with no sitting president or vice president competing) since 1952 with highly competitive primaries for both major political parties. This study uses content analysis to investigate news coverage (national newspapers, network television news, and local newspapers) of the 2008 American presidential primary campaign. Most themes in the news concerned the horse race (66%) with somewhat more emphasis on the candidates’ character (18%) than their policy proposals (15%). The most common topics of horse race comments were campaign strategy (24%), campaign events (19%), polls (17%), and predictions (12%). More news comments were positive (62%) than negative (32%) with few comments about the candidate’s defenses (7%). Most comments were unattributed (statements by journalists: 66%); candidates were quoted or paraphrased in about one in five comments; the remaining comments were from supporters (8%) or others (7%)