4,060 research outputs found
Time Dependent Saddle Node Bifurcation: Breaking Time and the Point of No Return in a Non-Autonomous Model of Critical Transitions
There is a growing awareness that catastrophic phenomena in biology and
medicine can be mathematically represented in terms of saddle-node
bifurcations. In particular, the term `tipping', or critical transition has in
recent years entered the discourse of the general public in relation to
ecology, medicine, and public health. The saddle-node bifurcation and its
associated theory of catastrophe as put forth by Thom and Zeeman has seen
applications in a wide range of fields including molecular biophysics,
mesoscopic physics, and climate science. In this paper, we investigate a simple
model of a non-autonomous system with a time-dependent parameter and
its corresponding `dynamic' (time-dependent) saddle-node bifurcation by the
modern theory of non-autonomous dynamical systems. We show that the actual
point of no return for a system undergoing tipping can be significantly delayed
in comparison to the {\em breaking time} at which the
corresponding autonomous system with a time-independent parameter undergoes a bifurcation. A dimensionless parameter
is introduced, in which is the curvature
of the autonomous saddle-node bifurcation according to parameter ,
which has an initial value of and a constant rate of change . We
find that the breaking time is always less than the actual point
of no return after which the critical transition is irreversible;
specifically, the relation is analytically obtained. For a system with a small , there exists a significant window of opportunity
during which rapid reversal of the environment can save the system from
catastrophe
Correlations of BMI-1 expression and telomerase activity in ovarian cancer tissues
Aim: To investigate the correlation between oncoprotein Bmi-1 and telomerase activity in ovarian cancer tissues. Methods: SP immunohistochemistry was adopted to detect the expression of Bmi-1 protein in tissues of 47 ovarian epithelial cancer cases. Modified telomeric repeat amplification protocol (TRAP, silver staining technique) was used to detect the telomerase activity. Results: While in 80.85% (38/47) of ovarian epithelial cancer cases Bmi-1 protein was overexpressed, 46.81% (22/47) had very strong expression level. Bmi-1 expression levels in ovarian carcinoma tissue differ depending on tissue grade (higher for G3 cancer cases — 93.10% than for grade G2 cases — 61.11%) and the stage of the disease (lower for phase II and phase III cases — 66.67% than for phase IV cases — 92.31%). In ovarian epithelial cancer tissues, 87.23% (41/47) demonstrated positive telomerase activity in contrast to zero activity in normal tissues. Majority (90.24%) of specimens with positive telomerase activity possessed high Bmi-1 expression levels. Spearman correlation analysis indicated that expression of Bmi-1 protein was positively correlated with the elevated telomerase activity. Conclusions: Bmi-1 protein is highly expressed in ovarian epithelial cancer tissues, and its expression level correlates with histological grade and clinical phase of the patients. Elevation of Bmi-1 expression is closely correlated to the increased telomerase activity.Цель: изучить корреляцию между экспрессией протеина Bmi-1 и активностью теломеразы при раке яичника. Методы: подобраны
оптимальные условия для SP-иммуногистохимии для выявления экспрессии белка Bmi-1 при эпителиальном раке
яичника (n = 47). Для определения активности теломеразы был использован усовершенствованый протокол амплификации
теломерных повторов (TRAP, методика окрашивания серебром). Результаты: в 80,85% (38/47) случаев рака яичника была
выявлена экспрессия белка Bmi-1, в 46,81% (22/47) случаев – на очень высоком уровне. Уровень экспрессии Bmi-1 зависел от
степени дифференцировки опухоли (при G3 экспрессия Bmi-1 (93,10%) была выше, чем при G2 (61,11%)) и от стадии заболе- G3 экспрессия 3 экспрессия Bmi-1 (93,10%) была выше, чем при G2 (61,11%)) и от стадии заболе- Bmi-1 (93,10%) была выше, чем при G2 (61,11%)) и от стадии заболе- -1 (93,10%) была выше, чем при -1 (93,10%) была выше, чем при G2 (61,11%)) и от стадии заболе- G2 (61,11%)) и от стадии заболе- G2 (61,11%)) и от стадии заболе- 2 (61,11%)) и от стадии заболевания
(уровень экпрессии ниже в стадиях II и III (66,67%), чем в стадии IV (92,31%)). В тканях эпителиального рака яичника
в 87,23% (41/47) случаев выявлена положительная теломеразная активность, в отличие от нулевой активности в нормальных
тканях. В большинстве исследованных случаев рака яичника (90,24%) при положительной активности теломеразы был отмечен
высокий уровень экспрессии Bmi-1. Корреляционный анализ Спирмана показал, что экспрессия белка Bmi-1 положительно
коррелирует с повышенной теломеразной активностью. Выводы: белок Bmi-1 экспрессирован на высоком уровне злокачествен- -1 экспрессирован на высоком уровне злокачествен- -1 экспрессирован на высоком уровне злокачественными
клетками эпителиального рака яичника, и экспрессия этого белка коррелирует с гистологической градацией и клинической
стадией рака. Увеличение экспрессии Bmi-1 коррелировало с повышенной теломеразной активностью
Dutch Author Recognition Test
Book reading shows large individual variability and correlates with better language ability and more empathy. This makes reading exposure an interesting variable to study. Research in English suggests that an author recognition test is the most reliable objective assessment of reading frequency. In this article, we describe the efforts we made to build and test a Dutch author recognition test (DART for older participants and DART_R for younger participants). Our data show that the test is reliable and valid, both in the Netherlands and in Belgium (split-half reliability over .9 with university students, significant correlations with language abilities) and can be used with a young, non-university population. The test is free to use for research purposes
Effect of tempering temperature on microstructure and properties of 65Mn steel for metallurgical saw blade
The continuous tempering treatment of 65 Mn steel for metallurgical saw blade was carried out in the temperature range of 200-620 °C by means of metallographic observation and mechanical property test. The results show that with the increase of tempering temperature, the strength and hardness of the pattern decrease continuously, and the impact value, section shrinkage and elongation change significantly. The experimental results provide a technical reference for preventing the failure of the saw blade during operation
Light-Front Quantization and AdS/QCD: An Overview
We give an overview of the light-front holographic approach to strongly
coupled QCD, whereby a confining gauge theory, quantized on the light front, is
mapped to a higher-dimensional anti de Sitter (AdS) space. The framework is
guided by the AdS/CFT correspondence incorporating a gravitational background
asymptotic to AdS space which encodes the salient properties of QCD, such as
the ultraviolet conformal limit at the AdS boundary at , as well as
modifications of the geometry in the large infrared region to describe
confinement and linear Regge behavior. There are two equivalent procedures for
deriving the AdS/QCD equations of motion: one can start from the Hamiltonian
equation of motion in physical space time by studying the off-shell dynamics of
the bound state wavefunctions as a function of the invariant mass of the
constituents. To a first semiclassical approximation, where quantum loops and
quark masses are not included, this leads to a light-front Hamiltonian equation
which describes the bound state dynamics of light hadrons in terms of an
invariant impact variable which measures the separation of the partons
within the hadron at equal light-front time. Alternatively, one can start from
the gravity side by studying the propagation of hadronic modes in a fixed
effective gravitational background. Both approaches are equivalent in the
semiclassical approximation. This allows us to identify the holographic
variable in AdS space with the impact variable . Light-front
holography thus allows a precise mapping of transition amplitudes from AdS to
physical space-time. The internal structure of hadrons is explicitly introduced
and the angular momentum of the constituents plays a key role.Comment: Invited talk presented by GdT at the XIV School of Particles and
Fields, Morelia, Mexico, November 8-12, 201
A novel five-phase fault-tolerant modular in-wheel permanent-magnet synchronous machine for electric vehicles
© 2015 AIP Publishing LLC. This paper describes a five-phase fault-tolerant modular in-wheel permanent-magnet synchronous machine (PMSM) for electric vehicles. By adopting both the analytical and finite-element methods, the magnetic isolation abilities of some typical slot/pole combinations are analyzed, and a new fractional-slot concentrated winding topology that features hybrid single/double-layer concentrated windings and modular stator structure is developed. For the proposed hybrid single/double-layer concentrated windings, feasible slot/pole combinations are studied for three-, four-, and five-phase PMSMs. A five-phase in-wheel PMSM that adopts the proposed winding topology is designed and compared with the conventional PMSM, and the proposed machine shows advantages of large output torque, zero mutual inductances, low short-circuit current, and high magnetic isolation ability. Some of the analysis results are verified by experiments
Innovating Management Control by Dynamic Analysis of Pareto in a Hotel Business
This paper deals with the Pareto Analysis of problems observed and criticized by clients in a hotel establishment in the municipality of Porto Velho, capital of the State of Rondocirc;nia. The general objective of the research is to study the use of Pareto Analysis in these problems that annoy the clients; (1), to group the data in descending order of frequency and to calculate the cumulative values (2), and indicating innovation for managerial control through a tool for Pareto Analysis in a dynamical way (3). The methodology of the qualitative-quantitative approach, of an exploratory nature, is adopted; the bibliographic survey and the field research are applied in support of the case study. Through the database system that the company under study possesses, the data necessary to be used in the Pareto Analysis are obtained, completing the first specific objective; the grouping of these data in descending order of absolute frequency, the calculation of the cumulative values, the preparation of the Pareto Diagram and the analysis carried out successfully completed the second specific objective; and finally the study is finished with the creation of a tool that allows a more dynamic analysis of the scenario in which the company is inserted, as a proposal of innovation for the institution to perform its practical and dynamic analyzes, useful in decision making. This study is a contribution of the academy to managers who work with complex decisions in hotel or related establishments interested in customer satisfaction
Stakeholder Perception in the Organizational Environment Focusing on Behavior
Behavior has meaning for the organizational climate, leading to studies such as this related to stakeholder perception in the institutional environment. This task is based on the Behavioral Management Theory and the additional concepts required. It was sought to know the relation of the intervening factors, from the method of case study of qualitative-quantitative nature, in order to establish comparisons and to produce the results. The general objective is to study the stakeholder perception process in the organizational environment focused on the behavioral effect and it has as specific objectives to treat and identify the relationship of the intervening factors with the organizational climate in the face of data collected among the consulted, to perform the SWOT on the positioning of individuals in the organizational environment and how this perception is characterized in the face of the organizational climate present in the consulted organ. The research indicates that the majority of respondents stated that the organizational climate present in the organ consulted satisfactory, propitiates the good organizational environment in the organ. Confrontation between the theoretical indicatives and the reality identified in the institutional environment allows to affirm that in fact there is internal influence, such as the motivation and external organization, as the possibility of losing the employee attracted by other opportunities outside the institution. Analysis allows to identify the need for physical improvement of the professional space, and in the interaction between stakeholders; redistribution of work that avoids overload; but the motivation and good internal relation between the individuals surpass the expectation. This work interests the managers in public organs and other interested in the subject here treated
Auto-tracking system for human lumbar motion analysis
Previous lumbar motion analyses suggest the usefulness of quantitatively characterizing spine motion. However, the application of such measurements is still limited by the lack of user-friendly automatic spine motion analysis systems. This paper describes an automatic analysis system to measure lumbar spine disorders that consists of a spine motion guidance device, an X-ray imaging modality to acquire digitized video fluoroscopy (DVF) sequences and an automated tracking module with a graphical user interface (GUI). DVF sequences of the lumbar spine are recorded during flexion-extension under a guidance device. The automatic tracking software utilizing a particle filter locates the vertebra-of-interest in every frame of the sequence, and the tracking result is displayed on the GUI. Kinematic parameters are also extracted from the tracking results for motion analysis. We observed that, in a bone model test, the maximum fiducial error was 3.7%, and the maximum repeatability error in translation and rotation was 1.2% and 2.6%, respectively. In our simulated DVF sequence study, the automatic tracking was not successful when the noise intensity was greater than 0.50. In a noisy situation, the maximal difference was 1.3 mm in translation and 1° in the rotation angle. The errors were calculated in translation (fiducial error: 2.4%, repeatability error: 0.5%) and in the rotation angle (fiducial error: 1.0%, repeatability error: 0.7%). However, the automatic tracking software could successfully track simulated sequences contaminated by noise at a density ≤ 0.5 with very high accuracy, providing good reliability and robustness. A clinical trial with 10 healthy subjects and 2 lumbar spondylolisthesis patients were enrolled in this study. The measurement with auto-tacking of DVF provided some information not seen in the conventional X-ray. The results proposed the potential use of the proposed system for clinical applications. © 2011 - IOS Press and the authors. All rights reserved.postprin
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