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 $p(\tau)$ 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} $\hat{\tau}$ at which the corresponding autonomous system with a time-independent parameter $p_{a}= p(\hat{\tau})$ undergoes a bifurcation. A dimensionless parameter $\alpha=\lambda p_0^3V^{-2}$ is introduced, in which $\lambda$ is the curvature of the autonomous saddle-node bifurcation according to parameter $p(\tau)$, which has an initial value of $p_{0}$ and a constant rate of change $V$. We find that the breaking time $\hat{\tau}$ is always less than the actual point of no return $\tau^*$ after which the critical transition is irreversible; specifically, the relation $\tau^*-\hat{\tau}\simeq 2.338(\lambda V)^{-\frac{1}{3}}$ is analytically obtained. For a system with a small $\lambda V$, there exists a significant window of opportunity $(\hat{\tau},\tau^*)$ 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

Untethered Swarm Robots with Independent Crawling and Rolling Motions

We have demonstrated mm-scale untethered robots using a single axis magnetic field control to have swarm operations and independent crawling and rolling motions. There are three distinctive accomplishments as compared with the state-of-art: 1) working prototypes in the mm-scale with a moving speed of ~50 body size/s under the crawling mode operation; (2) an ultra-high moving speed of ~277 body size/s under the rolling mode operation; and 3) demonstrations of several complex swarming behaviors including chain-shape formation, crawling, and separation As such, the proposed operation schemes provides a new class of strategies to control mm-scale swarm robots for potential environmental and medical applications, such as minimally invasive surgeries

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 $z \to 0$, as well as modifications of the geometry in the large $z$ 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 $\zeta$ 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 $z$ in AdS space with the impact variable $\zeta$. 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

Asymmetrical pMUTs for Focused Acoustic Pressure by Reinforcement Learning

To increase the energy utilization of a pMUT array, an advanced design scheme for asymmetrical piezoelectric micromachined ultrasonic transducers (pMUTs) has been developed with focused acoustic pressure via the deep deterministic policy gradient (DDPG) algorithm. Three distinctive accomplishments have been achieved in: 1) a highly-efficient interface platform between Python and COMSOL for asymmetry factor (AF) simulations; 2) fast freeform pMUT designs without the initial dataset; and 3) superior designs with increased 34% pressure outputs for potential applications such as contact-less haptics. As such, the proposed design scheme could be applied to other MEMS devices to improve system efficiency