743 research outputs found
After Many a Summer Dies the Swan
For a brilliant satire on humanity, I can think of no better author to turn to than Aldous Huxley. His rhetoric is flawless, his characters unbelievably typical, and his satire tinged with just the right amount of reality to render it plausible. Born in England, Mr. Huxley has no more mercy on his own countrymen than he has on those of other nationalities. His satire is universal and completely nonpartisan
Synthesis of some acridine derivatives of possible pharmacological value
The German chemist Ehrlich may be regarded as
the father of chemotherapy for, as early as 1904, he
said, with true vision, "What we seek is 'specific
chemotherapy.' That is, we are in search of a drug
capable of destroying certain parasites without, at
the same time, causing too much damage to the host"
and his words still hold good to -day. His aim and
that of all subsequent workers in this field has been
expressed in other words by saying that "we seek a
hidden key which can alone open a certain door."
Although a considerable amount of work was
accomplished in the field of chemotherapeutic agents
during the intervening years modern research was
given a great impetus following the publication in
1935 of the work of Domagk dealing with the clinical
use of prontosil against diseases caused by haemolytic
streptococci. The investigation of this branch of
chemistry is, however, still in its infancy.
At the present time, in spite. of the recent most
intensive research, there are no general rules to
guide the research work in chemotherapy and it is
recognised that much experimental work has yet to be
accomplished before any attempt can be made to
formulate a satisfactory theory which would give a
general correlation between chemical structure and
chemotherapeutic action. "Meantime, it is possible
to argue as to whether, in the search for new drugs,
intuition is still of more value for guidance than
the collected fruits of experience. One thing,
however, is not arguable and that is that in either
case one must still apply a great deal of patience to
the search."
In the course of these synthetical studies it
became apparent that methoxy groups and methylenedioxy
groups substituted in the 4:5 positions to a 2- carboxyl
group in a diphenylamine -2- carboxylic acid in many
cases led to inefficient ring closure with sulphuric
acid or phosphorus oxychloride. On the other hand a
chlorine substituted in the 5- position appears to lead
to successful ring closure.
A possible theoretical explanation is advanced
for this effect and a suggestion made that further
information on the influence of substituents on such
ring closures is highly desirable
Reactive attachment disorder in the general population: a hidden ESSENCE disorder
Reactive attachment disorder (RAD) is a severe disorder of social functioning. Previous research has shown that children with RAD may have poor cognitive and language abilities; however, findings mainly come from biased, institutionalised samples. This paper describes the characteristics of all children who were given a suspected or likely diagnosis of reactive attachment disorder in an epidemiological study of approximately 1,600 children investigating the prevalence of RAD in the general population. We found that children with RAD are more likely to have multiple comorbidities with other disorders, lower IQs than population norms, more disorganised attachment, more problem behaviours, and poorer social skills than would be found in the general population and therefore have a complex presentation than can be described as ESSENCE. We discuss the clinical and educational implications
Perceived Decision-Making Pressures on Community Bank Chief Executives
The community-banking environment has experienced high levels of stress from increasing regulation, poor loan performance, investment devaluation, lower bank revenues, and public scrutiny during the period since 2008. The CEO decision-making process as a result, receives influence from several stakeholder groups with interests in differing outcomes. The objectives of this research were to identify and rank by importance the most pressing issues that develop decision-making stress among community banking executives. The examination of priorities and concerns facing a selected group of community bank CEOs utilizing an online Delphi method to determine the types of contextual cues (situational variables) that created the greatest levels of perceived pressure among the executives polled
Interpretation of cirrus cloud properties using coincident satellite and lidar data during the FIRE cirrus IFO
The First ISCCP Regional Experiment (FIRE) Cirrus Intensive Field Observations (IFO) provide an opportunity to examine the relationships between the satellite observed radiances and various parameters which describe the bulk properties of clouds, such as cloud amount and cloud top height. Lidar derived cloud altitude data, radiosonde data, and satellite observed radiances are used to examine the relationships between visible reflectance, infrared emittance, and cloud top temperatures for cirrus clouds
The 27-28 October 1986 FIRE IFO cirrus case study: Cirrus parameter relationships derived from satellite and lidar data
Cirrus cloud radiative and physical characteristics are determined using a combination of ground-based, aircraft, and satellite measurements taken as part of the First ISCCP Regional Experiment (FIRE) Cirrus Intensive Field Observations (IFO) during October and November 1986. Lidar backscatter data are used to define cloud base, center, and top heights and the corresponding temperatures. Coincident GOES 4 km visible (0.65 microns) and 8 km infrared window (11.5 microns) radiances are analyzed to determine cloud emittances and reflectances. Infrared optical depth is computed from the emittance results. Visible optical depth is derived from reflectance using a theoretical ice crystal scattering model and an empirical bidirectional reflectance mode. No clouds with visible optical depths greater than 5 or infrared optical depths less than 0.1 were used in the analysis. Average cloud thickness ranged from 0.5 km to 8 km for the 71 scenes. An average visible scattering efficiency of 2.1 was found for this data set. The results reveal a significant dependence of scattering efficiency on cloud temperature
Estimation of Asian dust aerosol effect on cloud radiation forcing using Fu-Liou radiative model and CERES measurements
International audienceThe impact of Asian dust on cloud radiative forcing during 2003?2006 is studied by using the Clouds and Earth's Radiant Energy Budget Scanner (CERES) data and the Fu-Liou radiative transfer model. Analysis of satellite data shows that the dust aerosol significantly reduced the cloud cooling effect at TOA. In dust contaminated cloudy regions, the 4-year mean values of the instantaneous shortwave, longwave and net cloud radiative forcing are ?138.9, 69.1, and ?69.7 Wm?2, which are 57.0, 74.2, and 46.3%, respectively, of the corresponding values in pristine cloudy regions. The satellite-retrieved cloud properties are significantly different in the dusty regions and can influence the radiative forcing indirectly. The contributions to the cloud radiation forcing by the dust direct, indirect and semi-direct effects are estimated using combined satellite observations and Fu-Liou model simulation. The 4-year mean value of combination of indirect and semi-direct shortwave radiative forcing (SWRF) is 82.2 Wm?2, which is 78.4% of the total dust effect. The direct effect is only 22.7 Wm?2, which is 21.6% of the total effect. Because both first and second indirect effects enhance cloud cooling, the aerosol-induced cloud warming is mainly the result of the semi-direct effect of dust
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Retrievals of thick cloud optical depth from the Geoscience Laser Altimeter System (GLAS) by calibration of solar background signal
Laser beams emitted from the Geoscience Laser Altimeter System (GLAS), as well as other spaceborne laser instruments, can only penetrate clouds to a limit of a few optical depths. As a result, only optical depths of thinner clouds (< about 3 for GLAS) are retrieved from the reflected lidar signal. This paper presents a comprehensive study of possible retrievals of optical depth of thick clouds using solar background light and treating GLAS as a solar radiometer. To do so one must first calibrate the reflected solar radiation received by the photon-counting detectors of the GLAS 532-nm channel, the primary channel for atmospheric products. Solar background radiation is regarded as a noise to be subtracted in the retrieval process of the lidar products. However, once calibrated, it becomes a signal that can be used in studying the properties of optically thick clouds. In this paper, three calibration methods are presented: (i) calibration with coincident airborne and GLAS observations, (ii) calibration with coincident Geostationary Opera- tional Environmental Satellite (GOES) and GLAS observations of deep convective clouds, and (iii) cali- bration from first principles using optical depth of thin water clouds over ocean retrieved by GLAS active remote sensing. Results from the three methods agree well with each other. Cloud optical depth (COD) is retrieved from the calibrated solar background signal using a one-channel retrieval. Comparison with COD retrieved from GOES during GLAS overpasses shows that the average difference between the two retriev- als is 24%. As an example, the COD values retrieved from GLAS solar background are illustrated for a marine stratocumulus cloud field that is too thick to be penetrated by the GLAS laser. Based on this study, optical depths for thick clouds will be provided as a supplementary product to the existing operational GLAS cloud products in future GLAS data releases
Surface-Based Observations of Contrail Occurrence Over the US, Apr. 1993 to Apr. 1994
Surface observers stationed at 19 U.S. Air Force Bases and Army Air Stations recorded the daytime occurrence of contrails and cloud fraction on an hourly basis for the period April 1993 through April 1994. Each observation uses one of four main categories to report contrails as unobserved, non-persistent, persistent, and indeterminate. Additional classification includes the co-occurrence of cirrus with each report. The data cover much of the continental U.S. including locations near major commercial air routes. The mean annual frequency of occurrence in unobstructed viewing conditions is 13 percent for these sites. Contrail occurrence varied substantially with location and season. Most contrails occurred during the winter months and least during the summer with a pronounced minimum during July. Although nocturnal observations are not available, it appears that the contrails have a diurnal variation that peaks during mid morning over most areas. Contrails were most often observed in areas near major commercial air corridors and least often over areas far removed from the heaviest air traffic. A significant correlation exists between mean contrail frequency and aircraft fuel usage above 7 km suggesting predictive potential for assessing future contrail effects on climate
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