46 research outputs found
Infrared absorbance spectroscopy of aqueous proteins : comparison of transmission and ATR data collection and analysis for secondary structure fitting
Attenuated total reflectance (ATR) infrared absorbance spectroscopy of proteins in aqueous solution is much easier to perform than transmission spectroscopy, where short pathâlength cells need to be assembled reproducibly. However, the shape of the resulting ATR infrared spectrum varies with the refractive index of the sample and the instrument configuration. Refractive index in turn depends on the absorbance of the sample. In this work, it is shown that a room temperature triglycine sulfate detector and a ZnSe ATR unit can be used to collect reproducible spectra of proteins. A simple method for transforming the protein ATR spectrum into the shape of the transmission spectrum is also given, which proceeds by approximating a KramersâKrönigâdetermined refractive index of water as a sum of four linear components across the amide I and II regions. The light intensity at the crystal surface (with 45° incidence) and its rate of decay away from the surface is determined as a function of the wave numberâdependent refractive index as well as the decay of the evanescent wave from the surface. The result is a single correction factor at each wave number. The spectra were normalized to a maximum of 1 between 1600 cmâ1 and 1700 cmâ1 and a selfâorganizing map secondary structure fitting algorithm, SOMSpec, applied using the BioTools reference set. The resulting secondary structure estimates are encouraging for the future of ATR spectroscopy for biopharmaceutical characterization and quality control applications
Bibliometric characteristics of the journal Science: Pre-Koshland, Koshland and post-Koshland period
Beyond forcing scenarios: predicting climate change through response operators in a coupled general circulation model
Global Climate Models are key tools for predicting the future response of the climate system to a variety of natural and anthropogenic forcings. Here we show how to use statistical mechanics to construct operators able to flexibly predict climate change for a variety of climatic variables of interest. We perform our study on a fully coupled model - MPI-ESM v.1.2 - and for the first time we prove the effectiveness of response theory in predicting future climate response to CO2 increase on a vast range of temporal scales, from inter-annual to centennial, and for very diverse climatic quantities. We investigate within a unified perspective the transient climate response and the equilibrium climate sensitivity and assess the role of fast and slow processes. The prediction of the ocean heat uptake highlights the very slow relaxation to a newly established steady state. The change in the Atlantic Meridional Overturning Circulation (AMOC) and of the Antarctic Circumpolar Current (ACC) is accurately predicted. The AMOC strength is initially reduced and then undergoes a slow and only partial recovery. The ACC strength initially increases as a result of changes in the wind stress, then undergoes a slowdown, followed by a recovery leading to a overshoot with respect to the initial value. Finally, we are able to predict accurately the temperature change in the Northern Atlantic
The global atmospheric electrical circuit and climate
Evidence is emerging for physical links among clouds, global temperatures, the global atmospheric electrical circuit and cosmic ray ionisation. The global circuit extends throughout the atmosphere from the planetary surface to the lower layers of the ionosphere. Cosmic rays are the principal source of atmospheric ions away from the continental boundary layer: the ions formed permit a vertical conduction current to flow in the fair weather part of the global circuit. Through the (inverse) solar modulation of cosmic rays, the resulting columnar ionisation changes may allow the global circuit to convey a solar influence to meteorological phenomena of the lower atmosphere. Electrical effects on non-thunderstorm clouds have been proposed to occur via the ion-assisted formation of ultra-fine aerosol, which can grow to sizes able to act as cloud condensation nuclei, or through the increased ice nucleation capability of charged aerosols. Even small atmospheric electrical modulations on the aerosol size distribution can affect cloud properties and modify the radiative balance of the atmosphere, through changes communicated globally by the atmospheric electrical circuit. Despite a long history of work in related areas of geophysics, the direct and inverse relationships between the global circuit and global climate remain largely quantitatively unexplored. From reviewing atmospheric electrical measurements made over two centuries and possible paleoclimate proxies, global atmospheric electrical circuit variability should be expected on many timescale
Artigos de periĂłdicos cientĂficos das ĂĄreas de informação no Brasil: evolução da produção e da autoria mĂșltipla
Individual, social, and environmental factors affecting salivary and fecal cortisol levels in captive pied tamarins (Saguinus bicolor)
This is the peer reviewed version of the following article: Price, E., Coleman, R., Ahsmann, J., Glendewar, G., Hunt, J., Smith, T. & Wormell, D. (2019). Individual, social, and environmental factors affecting salivary and fecal cortisol levels in captive pied tamarins (Saguinus bicolor). American Journal of Primatology, 81(8), which has been published in final form at https://doi.org/10.1002/ajp.23033. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingPied tamarins (Saguinus bicolor) are endangered New World primates, and in captivity
appear to be very susceptible to stress. We measured cortisol in 214 saliva samples
from 36 tamarins and in 227 fecal samples from 27 tamarins, and investigated
the effects of age, sex, pregnancy, rearing history, social status, weight, group
composition, and enclosure type using generalized linear mixed models. There was no
effect of age on either fecal or salivary cortisol levels. Female pied tamarins in late
pregnancy had higher fecal cortisol levels than those in early pregnancy, or
nonpregnant females, but there was no effect of pregnancy on salivary cortisol.
Females had higher salivary cortisol levels than males, but there was no effect of
rearing history. However, for fecal cortisol, there was an interaction between sex and
rearing history. Handâreared tamarins overall had higher fecal cortisol levels, but
while male parentâreared tamarins had higher levels than females who were parentâ
reared, the reverse was true for handâreared individuals. There was a trend towards
lower fecal cortisol levels in subordinate individuals, but no effect of status on
salivary cortisol. Fecal but not salivary cortisol levels declined with increasing weight.
We found little effect of group composition on cortisol levels in either saliva or feces,
suggesting that as long as tamarins are housed socially, the nature of the group is of
less importance. However, animals in offâshow enclosures had higher salivary and
fecal cortisol levels than individuals housed onâshow. We suggest that large onâshow
enclosures with permanent access to offâexhibit areas may compensate for the
effects of visitor disturbance, and a larger number of tamarins of the same species
housed close together may explain the higher cortisol levels found in tamarins living
in offâshow accommodation, but further research is needed