5,456 research outputs found
Homogenization Model for Aberrant Crypt Foci
Several explanations can be found in the literature about the origin of
colorectal cancer. There is however some agreement on the fact that the
carcinogenic process is a result of several genetic mutations of normal cells.
The colon epithelium is characterized by millions of invaginations, very small
cavities, called crypts, where most of the cellular activity occurs. It is
consensual in the medical community, that a potential first manifestation of
the carcinogenic process, observed in conventional colonoscopy images, is the
appearance of Aberrant Crypt Foci (ACF). These are clusters of abnormal crypts,
morphologically characterized by an atypical behavior of the cells that
populate the crypts. In this work an homogenization model is proposed, for
representing the cellular dynamics in the colon epithelium. The goal is to
simulate and predict, in silico, the spread and evolution of ACF, as it can be
observed in colonoscopy images. By assuming that the colon is an heterogeneous
media, exhibiting a periodic distribution of crypts, we start this work by
describing a periodic model, that represents the ACF cell-dynamics in a
two-dimensional setting. Then, homogenization techniques are applied to this
periodic model, to find a simpler model, whose solution symbolizes the averaged
behavior of ACF at the tissue level. Some theoretical results concerning the
existence of solution of the homogenized model are proven, applying a fixed
point theorem. Numerical results showing the convergence of the periodic model
to the homogenized model are presented.Comment: 26 pages, 4 figure
Magnetic fields around evolved stars: further observations of HO maser polarization
We aim to detect the magnetic field and infer its properties around four AGB
stars using HO maser observations. The sample we observed consists of the
following sources: the semi-regular variable RT Vir and the Mira variables AP
Lyn, IK Tau, and IRC+60370. We observed the 6 HO maser
rotational transition, in full-polarization mode, to determine its linear and
circular polarization. Based on the Zeeman effect, one can infer the properties
of the magnetic field from the maser polarization analysis. We detected a total
of 238 maser features, in three of the four observed sources. No masers were
found toward AP Lyn. The observed masers are all located between 2.4 and 53.0
AU from the stars. Linear and circular polarization was found in 18 and 11
maser features, respectively. We more than doubled the number of AGB stars in
which magnetic field has been detected from HO maser polarization, as our
results confirm the presence of fields around IK Tau, RT Vir and IRC+60370. The
strength of the field along the line of sight is found to be between 47 and 331
mG in the HO maser region. Extrapolating this result to the surface of the
stars, assuming a toroidal field ( r), we find magnetic fields
of 0.3-6.9 G on the stellar surfaces. If, instead of a toroidal field, we
assume a poloidal field ( r), then the extrapolated magnetic
field strength on the stellar surfaces are in the range between 2.2 and
115 G. Finally, if a dipole field ( r) is assumed, the
field strength on the surface of the star is found to be between 15.8 and
1945 G. The magnetic energy of our sources is higher than the thermal and
kinetic energy in the HO maser region of this class of objects. This leads
us to conclude that, indeed, magnetic fields probably play an important role in
shaping the outflows of evolved stars. (abridged)Comment: 15 pages, 5 figures, 7 tables. Accepted for publication in A&
Safeguarding Health at the Workplace: A Study of Work Engagement, Authenticity and Subjective Wellbeing among Religious Workers
: Research in work and organizational psychology has paid little attention to religious workers, something certainly surprising as faith-based organizations play a key role in the welfare state of many countries. This research shows that religious workers in a Catholic order present a high degree of subjective wellbeing, both in terms of flourishing and satisfaction with life in general,
and a positive balance of positive and negative feelings. More specifically, this study examines the relationship between authenticity and wellbeing amongst religious workers. Survey responses from 142 religious workers in Spain were analyzed using partial least squares path modelling. The results reveal that subjective wellbeing at work is positively related to authenticity. In addition, this relationship is mediated by their level of work engagement
Improved shape hardening function for bounding surface model for cohesive soils
AbstractA shape hardening function is developed that improves the predictive capabilities of the generalized bounding surface model for cohesive soils, especially when applied to overconsolidated specimens. This improvement is realized without any changes to the simple elliptical shape of the bounding surface, and actually reduces the number of parameters associated with the model by one
A Geometric Representation for the Proca Model
The Proca model is quantized in an open-path dependent representation that
generalizes the Loop Representation of gauge theories. The starting point is a
gauge invariant Lagrangian that reduces to the Proca Lagrangian when certain
gauge is selected.Comment: 10 pages, Late
Aurora at the pole and equator: overlapping functions of Aurora kinases in the mitotic spindle
The correct assembly and timely disassembly of the mitotic spindle is crucial for the propagation of the genome during cell division. Aurora kinases play a central role in orchestrating bipolar spindle establishment, chromosome alignment and segregation. In most eukaryotes, ranging from amoebas to humans, Aurora activity appears to be required both at the spindle pole and the kinetochore, and these activities are often split between two different Aurora paralogues, termed Aurora A and B. Polar and equatorial functions of Aurora kinases have generally been considered separately, with Aurora A being mostly involved in centrosome dynamics, whereas Aurora B coordinates kinetochore attachment and cytokinesis. However, double inactivation of both Aurora A and B results in a dramatic synergy that abolishes chromosome segregation. This suggests that these two activities jointly coordinate mitotic progression. Accordingly, recent evidence suggests that Aurora A and B work together in both spindle assembly in metaphase and disassembly in anaphase. Here, we provide an outlook on these shared functions of the Auroras, discuss the evolution of this family of mitotic kinases and speculate why Aurora kinase activity may be required at both ends of the spindle microtubules
Using Critical Thinking Styles to Inform Food Safety Behavior Communication Campaigns
Consumers have struggled with maintaining consistent food safety behaviors over the years, which has been affected partly by their limited food safety knowledge. Researchers in this study set to determine Florida residents’ food safety behaviors while also assessing their critical thinking styles. The social cognitive theory and the University of Florida critical thinking styles (UFCTI) inventory served as the guiding framework. The UFCTI has emerged as an effective tool in measuring how an individual’s critical thinking is expressed, performed, or done. Online survey responses were collected from 510 Florida residents and data were analyzed using non-probability and weighting measures. The majority of respondents washed their fresh fruits and vegetables before eating and washed their hands before food preparation. However, respondents were not as likely to disinfect their countertops before food preparation. Respondents exhibited infrequent food label reading behaviors, as well. When receiving food related information, seekers of information preferred printed fact sheets, bulletins or brochures, and demonstration or displays. Whereas, engagers preferred websites. Recommendations included developing communication efforts focused on personalized messages and targeted mediums centered around each critical thinking style. Food safety communication should emphasize the importance and risks of not reading food labels and cleaning countertops. Future research should determine how each critical thinking style uses the mediums where no significant difference was established. Research efforts should focus on expanding the UFCTI and assessing the contributions the social cognitive theory can add
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