1,006 research outputs found
Sarah Davies, James Harris, Stalinās World, Dictating the Soviet Order
Sarah Davies and James Harris have set themselves the task of trying to understand Stalin. They do this primarily through an examination of the kinds of information that Stalin had at hand, and through which he viewed the world. These two authors have spent years collectively culling and sifting through now available documents from Stalinās personal archivesāthe mass of daily reports prepared for his reading, private correspondence, drafts of speeches, texts, marginal comments on texts, and e..
Sarah Davies, James Harris, Stalinās World, Dictating the Soviet Order
Sarah Davies and James Harris have set themselves the task of trying to understand Stalin. They do this primarily through an examination of the kinds of information that Stalin had at hand, and through which he viewed the world. These two authors have spent years collectively culling and sifting through now available documents from Stalinās personal archivesāthe mass of daily reports prepared for his reading, private correspondence, drafts of speeches, texts, marginal comments on texts, and e..
The effects of membrane and cytoskeletal mechanics on cell adhesiveness
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (leaves 28-29).The cytoskeleton, the internal network of filaments that regulates cell shape and structure, has been implicated in several critical aspects of cell adhesion. Its role, however, has primarily been demonstrated as a component of the numerous intracellular signaling events that regulate cell surface receptors. In this study we sought to gain insight into how the mechanical properties of the cytoskeleton could affect adhesion. Specifically, we addressed how membrane deformability, which we demonstrate is critically dependent upon tethering to the cytoskeleton, could impact a whole cell adhesion assay. To modify membrane deformability, we treated cells with the pharmacological agents phalloidin, Latrinculin B, Cytochalasin D, colchicine, and Paclitaxel, which have varying effects on microfilaments and microtubules, two of the main constituents of the cytoskeleton. We found that dissolution of the actin cytoskeleton could reduce the number of adherent cells to a callogen-coated substrate by over 85%. We theorize that this is due largely to the inhibition of signaling events associated with the cytoskeleton, but it may also be affected by changes in shape and deformability. To truly understand the implications of this experiment, we believe further study using high-resolution force technology such as atomic force microscopy or magnetic bead microrheometry is necessary.by David Shearer.S.B
The Minnesota Multiphasic Personality Inventory-2 and Low Back Pain Surgery Outcome
Chronic back pain is a serious problem in the U.S. for which about 10% of back pain sufferers will undergo elective surgery. Unfortunately, back surgery is not successful in alleviating back pain in a substantial number of surgery patients. Various psychological and psychosocial variables have a demonstrated relationship to back surgery outcome. The most widely used personality test used to predict back surgery outcome is the Minnesota Multiphasic Personality Inventory (MMPJ). Past research has shown that elevations on three MMPI clinical scales (Hs, D, and Hy) are positively correlated with poor back surgery outcome. The current prospective study shows a similar pattern using the MMPI-2 to predict surgery outcome for 60 low back pain patients. It appears that past MMPI research in this area is applicable to the use of MMPI-2. These results also suggest that when MMPI-2 variables are combined with demographic and surgical variables, patients more likely to experience poor surgical outcome can be identified. There is evidence that elevations of the conversion V profile of the MMPI-2 may prospectively differentiate between successful and nonsuccessful surgery outcomes
An investigation of the Eigenvalue Calibration Method (ECM) using GASP for non-imaging and imaging detectors
Polarised light from astronomical targets can yield a wealth of information
about their source radiation mechanisms, and about the geometry of the
scattered light regions. Optical observations, of both the linear and circular
polarisation components, have been impeded due to non-optimised
instrumentation. The need for suitable observing conditions and the
availability of luminous targets are also limiting factors. GASP uses division
of amplitude polarimeter (DOAP) (Compain and Drevillon) to measure the four
components of the Stokes vector simultaneously, which eliminates the
constraints placed upon the need for moving parts during observation, and
offers a real-time complete measurement of polarisation. Results from the GASP
calibration are presented in this work for both a 1D detector system, and a
pixel-by-pixel analysis on a 2D detector system. Following Compain et al. we
use the Eigenvalue Calibration Method (ECM) to measure the polarimetric
limitations of the instrument for each of the two systems. Consequently, the
ECM is able to compensate for systematic errors introduced by the calibration
optics, and it also accounts for all optical elements of the polarimeter in the
output. Initial laboratory results of the ECM are presented, using APD
detectors, where errors of 0.2% and 0.1{\deg} were measured for the degree of
linear polarisation and polarisation angle respectively. Channel-to-channel
image registration is an important aspect of 2-D polarimetry. We present our
calibration results of the measured Mueller matrix of each sample, used by the
ECM. A set of Zenith flat-field images were recorded during an observing
campaign at the Palomar 200 inch telescope in November 2012. From these we show
the polarimetric errors from the spatial polarimetry indicating both the
stability and absolute accuracy of GASP.Comment: Accepted for publication in Experimental Astronom
The relationship between imagery type and collective efficacy in elite and non elite athletes
This study investigated the relationship between imagery function and individual perceptions of collective efficacy as a function of skill level. Elite (n = 70) and non elite (n = 71) athletes from a number of interactive team sports completed the Sport Imagery Questionnaire (SIQ) and the Collective Efficacy Inventory (CEI). Multiple hierarchical regression analysis was then used to examine which SIQ sub-scales predicted individual perceptions of collective efficacy. For the elite sample, Motivational General-Mastery (MG-M) imagery accounted for approximately 17% of the variance in collective efficacy scores. No significant predictions were observed in the non elite sample. The findings suggest MG-M imagery as a potential technique to improve levels of collective efficacy although competitive level may moderate the effectiveness of such intervention
Novel muon imaging techniques
Owing to the high penetrating power of high-energy cosmic ray muons, muon imaging techniques can be used to image large bulky objects, especially objects with heavy shielding. Muon imaging systems work just like CT scanners in the medical imaging fieldāthat is, they can reveal information inside of a target. There are two forms of muon imaging techniques: muon absorption imaging and muon multiple scattering imaging. The former is based on the flux attenuation of muons, and the latter is based on the multiple scattering of muons in matter. The muon absorption imaging technique is capable of imaging very large objects such as volcanoes and large buildings, and also smaller objects like spent fuel casks; the muon multiple scattering imaging technique is best suited to inspect smaller objects such as nuclear waste containers. Muon imaging techniques can be applied in a broad variety of fields, i.e. from measuring the magma thickness of volcanoes to searching for secret cavities in pyramids, and from monitoring the borders of countries checking for special nuclear materials to monitoring the spent fuel casks for nuclear safeguards applications. In this paper, the principles of muon imaging are reviewed. Image reconstruction algorithms such as Filtered Back Projection and Maximum Likelihood Expectation Maximization are discussed. The capability of muon imaging techniques is demonstrated through a Geant4 simulation study for imaging a nuclear spent fuel cask
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