Mathematic modeling of the Earth's surface and the process of remote sensing

It is shown that real data from remote sensing of the Earth from outer space are not best suited to the search for optimal procedures with which to process such data. To work out the procedures, it was proposed that data synthesized with the help of mathematical modeling be used. A criterion for simularity to reality was formulated. The basic principles for constructing methods for modeling the data from remote sensing are recommended. A concrete method is formulated for modeling a complete cycle of radiation transformations in remote sensing. A computer program is described which realizes the proposed method. Some results from calculations are presented which show that the method satisfies the requirements imposed on it

A performance comparison of the contiguous allocation strategies in 3D mesh connected multicomputers

The performance of contiguous allocation strategies can be significantly affected by the distribution of job execution times. In this paper, the performance of the existing contiguous allocation strategies for 3D mesh multicomputers is re-visited in the context of heavy-tailed distributions (e.g., a Bounded Pareto distribution). The strategies are evaluated and compared using simulation experiments for both First-Come-First-Served (FCFS) and Shortest-Service-Demand (SSD) scheduling strategies under a variety of system loads and system sizes. The results show that the performance of the allocation strategies degrades considerably when job execution times follow a heavy-tailed distribution. Moreover, SSD copes much better than FCFS scheduling strategy in the presence of heavy-tailed job execution times. The results also show that the strategies that depend on a list of allocated sub-meshes for both allocation and deallocation have lower allocation overhead and deliver good system performance in terms of average turnaround time and mean system utilization

Altered perception of facially expressed tiredness in insomnia

The present study compared normal sleepers and individuals displaying insomnia symptoms in their ratings for the expression intensity of tiredness and alertness whilst observing tired and neutral faces. Fifty-six normal sleepers and 58 individuals with insomnia symptoms observed 98 facial photographs (49 neutral, 49 tired). Using a visual analogue scale, participants were required to rate the extent to which each face appeared as tired and alert. Tired faces were created by manipulating neutral photographs to include previously identified facial tiredness cues. All participants rated sleep-related faces as more tired and less alert relative to neutral photographs. A significant Group × Face × Rating interaction demonstrated that, compared with normal sleepers, the insomnia symptoms group showed lower ratings for the expression of tiredness, but not alertness, whilst observing the tired faces. The findings suggest that the presence of insomnia symptoms is associated with reduced ratings of expression intensity for sleep-related facial photographs displaying tiredness. These outcomes add to the body of literature on how facial cues of tiredness are perceived by those with insomnia symptoms. Further work is required to elucidate the mechanisms underlying the relationship between insomnia symptoms and reduced perceptions of facially expressed tiredness

Report of IRPA task group on the impact of the eye lens dose limits

In 2012 IRPA established a task group (TG) to identify key issues in the implementation of the revised eye lens dose limit. The TG reported its conclusions in 2013. In January 2015, IRPA asked the TG to review progress with the implementation of the recommendations from the early report and to collate current practitioner experience. This report presents the results of a survey on the view of the IRPA professionals on the new limit to the lens of the eye and on the wider issue of tissue reactions. Recommendations derived from the survey are presented. This report was approved by IRPA Executive Council on 31 January 2017

A Glacial History of Roberts Massif, Central Transantarctic Mountains, Antarctica, Using Cosmogenic 3He, 10Be, and 21Ne Surface Exposure Ages

Ice-free areas at high elevation in the central Transantarctic Mountains preserve moraines and drift deposits that delineate the former thickness and extent of the East Antarctic Ice Sheet (EAIS); cosmogenic exposure ages on these features indicate when the ice sheet was as or more extensive than today. Approximately 30 existing cosmogenic-nuclide exposure ages from scattered locations within these deposits suggest that some moraines and drift sheets are at least 5 Ma old. Those ages imply that the age range of these deposits may span warm periods during the Miocene and Pliocene, during which the EAIS is hypothesized to have been much smaller than present and which constitute potentially important geologic analogues for future warm climates. Therefore, to evaluate the long-term stability of the ice sheet, I have obtained 3He, 10Be, and 21Ne exposure ages from 150 glacially-transported clasts on distinct ice-marginal landforms at Roberts Massif at the head of Shackleton Glacier. The majority of these data comprise 3He measurements on pyroxene extracted from Ferrar dolerite clasts and prepared using a refined HF etching method that improves both measurement throughput and reproducibility. I address the common problem of scatter in exposure ages due to cosmogenic-nuclide inheritance by (i) measuring large numbers of exposure ages, including ~7 from each landform, and (ii) resampling and averaging approaches based on both statistical criteria and field observations of boulder characteristics and geomorphic context. Moraines at Roberts Massif are openwork boulder belts characteristic of deposition by cold-based ice, which is consistent with present climate and glaciological conditions. Additionally, the lack of glaciofluvial deposits at Roberts Massif suggests that temperatures have not been sufficiently warm to induce surface melting of the ice at this location since at least the beginning of my glacial record. Apparent exposure ages at this site range from ~400 ka to 13 Ma, with individual moraine ages as old as ~8 Ma, which shows that these landforms record glacial events in the central Transantarctic Mountains since the mid-Miocene. I also use the 10Be/21Ne nuclide pair to constrain erosion rates of Beacon Sandstone boulders t

A multiscale hybrid model for pro-angiogenic calcium signals in a vascular endothelial cell

Cytosolic calcium machinery is one of the principal signaling mechanisms by which endothelial cells (ECs) respond to external stimuli during several biological processes, including vascular progression in both physiological and pathological conditions. Low concentrations of angiogenic factors (such as VEGF) activate in fact complex pathways involving, among others, second messengers arachidonic acid (AA) and nitric oxide (NO), which in turn control the activity of plasma membrane calcium channels. The subsequent increase in the intracellular level of the ion regulates fundamental biophysical properties of ECs (such as elasticity, intrinsic motility, and chemical strength), enhancing their migratory capacity. Previously, a number of continuous models have represented cytosolic calcium dynamics, while EC migration in angiogenesis has been separately approached with discrete, lattice-based techniques. These two components are here integrated and interfaced to provide a multiscale and hybrid Cellular Potts Model (CPM), where the phenomenology of a motile EC is realistically mediated by its calcium-dependent subcellular events. The model, based on a realistic 3-D cell morphology with a nuclear and a cytosolic region, is set with known biochemical and electrophysiological data. In particular, the resulting simulations are able to reproduce and describe the polarization process, typical of stimulated vascular cells, in various experimental conditions.Moreover, by analyzing the mutual interactions between multilevel biochemical and biomechanical aspects, our study investigates ways to inhibit cell migration: such strategies have in fact the potential to result in pharmacological interventions useful to disrupt malignant vascular progressio

Iterative Sorting for 4DCT Images Based ON Internal Anatomy Motion

Geometric uncertainties caused by respiratory motion complicate radiotherapy treatment planning. Therefore 4D CT imaging is important in characterizing anatomy motion during breathing. Current 4D CT imaging techniques using multislice CT scanners involve multiple scans at several axial positions and retrospective sorting processes. Most sorting methods are based on externally monitored signals recorded by external monitoring instruments, which may not always accurately catch the actual breathing status and may lead to severe discontinuity artifacts in the sorted CT volumes. We propose a method to reconstruct time-resolved CT volumes based on internal motion to avoid the inaccuracies caused by external breathing signals. In our method, we iteratively sort the 4D CT slices using internal motion based breathing indices. In each iteration, respiratory motion is estimated by updating a motion model to best match a deformed reference volume to each moving multi-slice sub-volumes. The breathing indices as well as the reference volumes are refined for each iteration based on the currently estimated respiratory motion. An example is presented to illustrate the feasibility of our 4D CT sorting method without using any external motion monitoring systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85803/1/Fessler229.pd

Abdominal DCE‐MRI reconstruction with deformable motion correction for liver perfusion quantification

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146361/1/mp13118_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146361/2/mp13118.pd

The Effect of Nonlinearity in Hybrid KMC-Continuum models

Recently there has been interest in developing efficient ways to model heterogeneous surface reactions with hybrid computational models that couple a KMC model for a surface to a finite difference model for bulk diffusion in a continuous domain. We consider two representative problems that validate a hybrid method and also show that this method captures the combined effects of nonlinearity and stochasticity. We first validate a simple deposition/dissolution model with a linear rate showing that the KMC-continuum hybrid agrees with both a fully deterministic model and its analytical solution. We then study a deposition/dissolution model including competitive adsorption, which leads to a nonlinear rate, and show that, in this case, the KMC-continuum hybrid and fully deterministic simulations do not agree. However, we are able to identify the difference as a natural result of the stochasticity coming from the KMC surface process. Because KMC captures inherent fluctuations, we consider it to be more realistic than a purely deterministic model. Therefore, we consider the KMC-continuum hybrid to be more representative of a real system