Microscopic formulation of the Zimm-Bragg model for the helix-coil transition

A microscopic spin model is proposed for the phenomenological Zimm-Bragg model for the helix-coil transition in biopolymers. This model is shown to provide the same thermophysical properties of the original Zimm-Bragg model and it allows a very convenient framework to compute statistical quantities. Physical origins of this spin model are made transparent by an exact mapping into a one-dimensional Ising model with an external field. However, the dependence on temperature of the reduced external field turns out to differ from the standard one-dimensional Ising model and hence it gives rise to different thermophysical properties, despite the exact mapping connecting them. We discuss how this point has been frequently overlooked in the recent literature.Comment: 11 pages, 2 figure

Design of engineered elastomeric substrate for stretchable active devices and sensors

In the field of flexible electronics, emerging applications require biocompatible and unobtrusive devices, which can withstand different modes of mechanical deformation and achieve low complexity in the fabrication process. Here, the fabrication of a mesa‐shaped elastomeric substrate, supporting thin‐film transistors (TFTs) and logic circuits (inverters), is reported. High‐relief structures are designed to minimize the strain experienced by the electronics, which are fabricated directly on the pillars' surface. In this design configuration, devices based on amorphous indium‐gallium‐zinc‐oxide can withstand different modes of deformation. Bending, stretching, and twisting experiments up to 6 mm radius, 20% uniaxial strain, and 180° global twisting, respectively, are performed to show stable electrical performance of the TFTs. Similarly, a fully integrated digital inverter is tested while stretched up to 20% elongation. As a proof of the versatility of mesa‐shaped geometry, a biocompatible and stretchable sensor for temperature mapping is also realized. Using pectin, which is a temperature‐sensitive material present in plant cells, the response of the sensor shows current modulation from 13 to 28 °C and functionality up to 15% strain. These results demonstrate the performance of highly flexible electronics for a broad variety of applications, including smart skin and health monitoring

Experiences and perceptions of natural hazards among international migrants living in Valparaiso, Chile

International migrants are a socially vulnerable group within the context of disasters. However, disasters research focusing on this group is limited. This problem is the primary focus of the present study. Aim: To explore responses, behaviors and experiences concerning natural hazards among migrants living in Valparaíso, Chile. Methods: Following a constructivist paradigm, we conducted a case study. We interviewed twenty migrants. The interviews were analyzed using thematic analysis. The study was peer-reviewed by Universidad del Desarrollo Ethics Committee. Results: Participants described intense emotional reactions when facing disasters that reduced their coping ability. Their limited knowledge about natural hazards and how to react, explain in part their responses and the difficulties they face. Participants compared their reactions with the behaviors exhibited by the local Chilean population who displayed very little fear and seemed to be used to these events. Finally, despite sharing the same native language, Spanish, preparation activities and warnings appear not to be reaching them. Conclusions: There is an urgent need to implement culturally sensitive preparation strategies, through migrants´ existing social networks, to address their needs and concerns and to enable them to cope with natural hazards. Emotional reactions appear to play an essential role in their response to natural disasters and should also be recognized and validated

Bullying behaviors and victimization experiences among adolescent students: the role of resilience

The role of resilience in the relationship between bullying behaviours, victimisation experiences, and self-efficacy was examined. Three hundred and 93 (191 male, 202 female) adolescents (mean age = 15.88, SD = .64) from schools in Coimbatore, India completed scales to assess bullying behaviours and victimisation experiences, resilience, and self-efficacy. Multigroup SEM, with separate groups created according to participant sex, revealed that resilience mediated the relationship between bullying behaviours and self-efficacy in males. Males engaged in bullying behaviours and experienced victimisation more frequently than females. The findings of the study have implication for designing intervention programs to enhance resilience among adolescents and young adults to enable them to manage bullying behaviours

Differential Effects of Exposure to Social Violence and Natural Disaster on Children's Mental Health

Disaster mental health, particularly postdisaster child mental health, is neglected in India. This study compares the impact of a natural disaster versus a spate of communal riots that occurred in Gujarat, India on January 26, 2001, and February 2002 to June 2002, respectively. Children aged 8-15 years from highly exposed earthquake sites (n = 128) and riot sites (n = 171) were approached for participation. A matching control sample of 351 nontrauma-exposed children was sought to compare with the trauma groups. Trauma and postdisaster adversities were studied using the UCLA disaster trauma tool; Goodman's Strengths and Difficulties Questionnaire was used to assess adjustment difficulties. Spearman's correlations were calculated to find associations between trauma items on UCLA's brief trauma scale and Strengths and Difficulties Questionnaire items. Results suggest that 7.6% of the earthquake sample and 38.7% from the riots sample manifested clinically significant mental health problems. The earthquake sample had 24.8% of those above clinical cutoff for probable posttraumatic stress disorder and the riots sample had 27.3% children who displayed posttraumatic stress symptoms. Children exposed to violence were psychologically more affected and in the presence of postdisaster adversities, posttraumatic stress symptoms persisted long term. This finding should enable development of differential psychotherapeutic interventions for children exposed to extreme events

Calorimetric Analysis Using DNA Thermal Stability to determine protein concentration

It was recently reported for two globular proteins and a short DNA hairpin in NaCl buffer that values of the transition heat capacities, Cp,DNA and Cp,PRO for equal concentrations (mg/mL) of DNA and proteins, are essentially equivalent (differ by less than 1%). Additional evidence for this equivalence is presented that reveals this phenomenon does not depend on DNA sequence, buffer salt, or Tm. Sequences of two DNA hairpins were designed to confer a near 20°C difference in their Tm’s. For the molecules, in NaCl and CsCl buffer the evaluated Cp,PRO and Cp,DNA were equivalent. Based on the equivalence of transition heat capacities, a calorimetric method was devised to determine protein concentrations in pure and complex solutions. The scheme uses direct comparisons between the thermodynamic stability of a short DNA hairpin standard of known concentration, and thermodynamic stability of protein solutions of unknown concentrations. In all cases, evaluated protein concentrations determined from the DNA standard curve agreed with the UV-Vis concentration for monomeric proteins. For samples of multimeric proteins, streptavidin (tetramer), Herpes Simplex Virus glycoprotein D (trimer/dimer), and a 16 base pair DNA duplex (dimer), evaluated concentrations were greater than determined by UV-Vis by factors of 3.94, 2.65, and 2.15, respectively

DNA-based Assay for Calorimetric determination of protein concentrations in pure or mixed solutions

It was recently reported that values of the transition heat capacities, as measured by differential scanning calorimetry, for two globular proteins and a short DNA hairpin in NaCl buffer are essentially equivalent, at equal concentrations (mg/mL). To validate the broad applicability of this phenomenon, additional evidence for this equivalence is presented that reveals it does not depend on DNA sequence, buffer salt, or transition temperature (Tm). Based on the equivalence of transition heat capacities, a calorimetric method was devised to determine protein concentrations in pure and complex solutions. The scheme uses direct comparisons between the thermodynamic stability of a short DNA hairpin standard of known concentration, and thermodynamic stability of protein solutions of unknown concentrations. Sequences of two DNA hairpins were designed to confer a near 20˚C difference in their Tm values. In all cases, evaluated protein concentrations determined from the DNA standard curves agreed with the UV-Vis concentration for monomeric proteins. For multimeric proteins evaluated concentrations were greater than determined by UV-Vis suggesting the calorimetric approach can also be an indicator of molecular stoichiometry

Origins of Fine Structure in DNA Melting Curves

With the help of one-dimensional random Potts-like model we study the origins of fine structure observed on differential melting profiles of double-stranded DNA. We assess the effects of sequence arrangement on DNA melting curves through the comparison of results for random, correlated, and block sequences. Our results re-confirm the smearing out the fine structure with the increase of chain length for all types of sequence arrangements and suggest fine structure to be a finite-size effect. We have found, that the fine structure in chains comprised of blocks with the correlation in sequence is more persistent, probably, because of increased sequence disorder the blocks introduce. Many natural DNAs show a well-expressed fine structure of melting profiles. In view of our results it might mean the existence of blocks in such DNAs. The very observation of fine structure may also mean, that there exists an optimal length for natural DNAs \emph{in vivo}.Comment: 15 pages, 9 figures, JCP submissio

Self-Regulation Shift Theory: A Dynamic Personal Agency Approach to Recovery Capital and Methodological Suggestions

Recovery capital highlights person and environmental resources associated with overcoming significant life challenges. This paper utilizes social cognitive theory as a framework for understanding how recovery capital functions in trauma adaptation. This theory outlines the bidirectional, dynamic interactions among person (e.g., cognitive and affective), behavioral (e.g., problem focused coping), and environmental variables (i.e., triadic reciprocal determinism). The value of this approach to understanding human adaptation to trauma is that it targets the self-regulatory processes that unfold for trauma survivors as they attempt to put their lives back together. Self-regulation shift theory (SRST), as an extension to social cognitive theory, is offered to explain how self-regulation is involved in both positive and negative adjustment. The theory uses a dynamical systems approach and highlights the mechanisms related to non-linear shifts in both positive and negative trauma recovery. According to SRST, trauma recovery may not be linear with threshold shifts (i.e., bifurcations) from one organized state (broken self) to another (empowered self). Coping self-efficacy perceptions are a critical factor influencing these threshold shifts. This paper concludes with a brief review of study designs and analytic procedures that can facilitate the application of non-linear dynamic research in this area