Driven activation versus thermal activation

Activated dynamics in a glassy system undergoing steady shear deformation is studied by numerical simulations. Our results show that the external driving force has a strong influence on the barrier crossing rate, even though the reaction coordinate is only weakly coupled to the nonequilibrium system. This "driven activation" can be quantified by introducing in the Arrhenius expression an effective temperature, which is close to the one determined from the fluctuation-dissipation relation. This conclusion is supported by analytical results for a simplified model system.Comment: 5 pages, 3 figure

Students' Schemata Activation in Extensive Reading at Stain Ponorogo

This study was aimed at investigating the extent to which the lecturer employed strategy and occupied effective classroom language to assist students' schemata activation on Extensive Reading class at English Department­STAIN Ponorogo. To meet with the objectives, qualita­tive case study formed the methodological basis of this present research involving an extensive reading lecturer as the research subject with one of her respective classes consisted of 32 students of fourth semester. The data were derived from lecturer's utterances (verbal) and body lan­guage (nonverbal). Those data were obtained from the transcripts of the recorded lecturer's utterances during two periods of meeting, and note­taking taken from observations and interviews. The results revealed that the lecturer used to employ questioning technique to activate students' schemata. Various strategies were predominantly occupied in lecturer's questioning behaviors to engage students in question­answer activities, such as probing, redirecting and reinforcement. Generally, those strate­gies were observed not only to provide motivation and focus students' at­tention towards the topic being discussed, but also to give a wide chance of opportunity for them to recall their prior knowledge and ease them to predict the content of reading texts they were going to read. Besides, the language the lecturer used under this investigation was fairly fulfilled the requirements to be communicative as some communicative features of talks were utilized properly, such as referential questions, content feed­back, and speech modification to optimize students' participation and performance in the process of reading

Integrin activation.

Integrin-mediated cell adhesion is important for development, immune responses, hemostasis and wound healing. Integrins also function as signal transducing receptors that can control intracellular pathways that regulate cell survival, proliferation, and cell fate. Conversely, cells can modulate the affinity of integrins for their ligands a process operationally defined as integrin activation. Analysis of activation of integrins has now provided a detailed molecular understanding of this unique form of "inside-out" signal transduction and revealed new paradigms of how transmembrane domains (TMD) can transmit long range allosteric changes in transmembrane proteins. Here, we will review how talin and mediates integrin activation and how the integrin TMD can transmit these inside out signals

Selective disruption of high sensitivity heat activation but not capsaicin activation of TRPV1 channels by pore turret mutations.

The capsaicin receptor transient receptor potential vanilloid (TRPV)1 is a highly heat-sensitive ion channel. Although chemical activation and heat activation of TRPV1 elicit similar pungent, painful sensation, the molecular mechanism underlying synergistic activation remains mysterious. In particular, where the temperature sensor is located and whether heat and capsaicin share a common activation pathway are debated. To address these fundamental issues, we searched for channel mutations that selectively affected one form of activation. We found that deletion of the first 10 amino acids of the pore turret significantly reduced the heat response amplitude and shifted the heat activation threshold, whereas capsaicin activation remained unchanged. Removing larger portions of the turret disrupted channel function. Introducing an artificial sequence to replace the deleted region restored sensitive capsaicin activation in these nonfunctional channels. The heat activation, however, remained significantly impaired, with the current exhibiting diminishing heat sensitivity to a level indistinguishable from that of a voltage-gated potassium channel, Kv7.4. Our results demonstrate that heat and capsaicin activation of TRPV1 are structurally and mechanistically distinct processes, and the pore turret is an indispensible channel structure involved in the heat activation process but is not part of the capsaicin activation pathway. Synergistic effect of heat and capsaicin on TRPV1 activation may originate from convergence of the two pathways on a common activation gate

Quantum resonant activation

Quantum resonant activation is investigated for the archetype setup of an externally driven two-state (spin-boson) system subjected to strong dissipation by means of both analytical and extensive numerical calculations. The phenomenon of resonant activation emerges in the presence of either randomly fluctuating or deterministic periodically varying driving fields. Addressing the incoherent regime, a characteristic minimum emerges in the mean first passage time to reach an absorbing neighboring state whenever the intrinsic time scale of the modulation matches the characteristic time scale of the system dynamics. For the case of deterministic periodic driving, the first passage time probability density function (pdf) displays a complex, multi-peaked behavior, which depends crucially on the details of initial phase, frequency, and strength of the driving. As an interesting feature we find that the mean first passage time enters the resonant activation regime at a critical frequency $\nu^*$ which depends very weakly on the strength of the driving. Moreover, we provide the relation between the first passage time pdf and the statistics of residence times.Comment: 14 pages, 13 figure

From Patient to Student Activation: Development of the Student Activation Measure

The Patient Activation Measure (PAM) was constructed to measure a person’s knowledge, skill, and confidence for self-managing one’s healthcare, or “activation” (Hibbard, Stockard, Mahoney, & Tusler, 2004). The Student Activation Measure (SAM) extends this definition to secondary education. The SAM is a short, positively worded measure that is intended to guide intervention planning. Six hundred three students from two disparate high schools located in the Pacific Northwest completed the measure and an accompanying demographic questionnaire. The respective schools provided the students’ GPAs and attendance records. Using Rasch modeling, the SAM evidenced excellent reliability and construct validity. One-way ANOVAs with post hoc Scheffe’s tests showed that higher SAM scores had significantly higher GPAs, fewer absences, increased time spent on homework, and less time spent on social media or playing video games. Overall, the SAM showed promise as both a research and intervention tool. In addition, the concept of activation has the added benefits of ease of measurement and bridges the gap between evidence-based practices in medicine and secondary education. Further research is needed to understand the properties of the SAM when used with students diagnosed with learning impairing disorders such as ADHD

TLR signaling in human antigen-presenting cells regulates MR1-dependent activation of MAIT cells

Mucosal-associated invariant T (MAIT) cells are an abundant innate-like T lymphocyte population that are enriched in liver and mucosal tissues. They are restricted by MR1, which presents antigens derived from a metabolic precursor of riboflavin synthesis, a pathway present in many microbial species, including commensals. Therefore, MR1-mediated MAIT cell activation must be tightly regulated to prevent inappropriate activation and immunopathology. Using an in vitro model of MR1-mediated activation of primary human MAIT cells, we investigated the mechanisms by which it is regulated. Uptake of intact bacteria by antigen presenting cells (APCs) into acidified endolysosomal compartments was required for efficient MR1-mediated MAIT cell activation, while stimulation with soluble ligand was inefficient. Consistent with this, little MR1 was seen at the surface of human monocytic (THP1) and B-cell lines. Activation with a TLR ligand increased the amount of MR1 at the surface of THP1 but not B-cell lines, suggesting differential regulation in different cell types. APC activation and NF-κB signaling were critical for MR1-mediated MAIT cell activation. In primary cells, however, prolonged TLR signaling led to downregulation of MR1-mediated MAIT cell activation. Overall, MR1-mediated MAIT cell activation is a tightly regulated process, dependent on integration of innate signals by APCs