Mechanisms of the negative shortwave cloud feedback in mid to high latitudes

Increases in cloud optical depth and liquid water path (LWP) are robust features of global warming model simulations in high latitudes, yielding a negative shortwave cloud feedback, but the mechanisms are still uncertain. We assess the importance of microphysical processes for the negative optical depth feedback by perturbing temperature in the microphysics schemes of two aquaplanet models, both of which have separate prognostic equations for liquid water and ice. We find that most of the LWP increase with warming is caused by a suppression of ice microphysical processes in mixed-phase clouds, resulting in reduced conversion efficiencies of liquid water to ice and precipitation. Perturbing the temperature-dependent phase partitioning of convective condensate also yields a small LWP increase. Together, the perturbations in large-scale microphysics and convective condensate partitioning explain more than two-thirds of the LWP response relative to a reference case with increased SSTs, and capture all of the vertical structure of the liquid water response. In support of these findings, we show the existence of a very robust positive relationship between monthly-mean LWP and temperature in CMIP5 models and observations in mixed-phase cloud regions only. In models, the historical LWP sensitivity to temperature is a good predictor of the forced global warming response poleward of about 45°, although models appear to overestimate the LWP response to warming compared to observations. We conclude that in climate models, the suppression of ice-phase microphysical processes that deplete cloud liquid water is a key driver of the LWP increase with warming and of the associated negative shortwave cloud feedback.

Interação em sala de aula de língua inglesa: o feedback como estratégia do desempenho assistido

This dissertation aims at characterizing the practices as well as the effects of a teacher s feedback in oral conversation interaction with students in an English Language classroom at a Primary School, 6th Grade in Açu/RN, Brazil. Therefore, this study is based on Vygotsky s (1975) and Bruner´s (1976) researches, which state that the learning process is constructed through interaction between a more experienced individual (teacher, parents and friends) and a learner who plays an active role, a re-constructor of knowledge. It is also based on Ur´s (2006) and Brookhart s (2008) studies (among other authors in Applied Linguistic) who defend that the feedback process needs to be evaluative and formative since it sets interfaces with both students autonomy and learning improvement. Our study is based on qualitative, quantitative and interpretive researches, whose natural environment (the classroom) is a direct source of data generated in this research through field observations/note-taking as well as through the transcriptions of five English classes audio taped. This study shows the following results: the teacher still seems to accept the patterns of interaction in the classroom that correspond to the IRE process (Initiation, Response, Evaluation) in behaviorist patterns: (1) he speaks and determines the turns of speech; (2) the teacher asks more questions and directs the activities most of the time; (3) the teacher´s feedback presents the following types: questioning, modeling, repeated response, praise, depreciation, positive/negative and sarcasm feedback, whose functions are to assess students' performance based on the rightness and wrongness of their responses. Thus, this implies to state that the feedback does not seem to help students improvement in terms of acquiring knowledge because of its normative effects/roles. Therefore, it is the teacher´s role to give evaluative and formative feedback to a student so that he/she should advance in the learning of the language and in the construction of knowledge

Mitigation of symmetry condition in positive realness for adaptive control

Feasibility of nonlinear and adaptive control methodologies in multivariable linear time-invariant systems with state-space realization (A, B, C) is apparently limited by the standard strictly positive realness conditions that imply that the product CB must be positive definite symmetric. This paper expands the applicability of the strictly positive realness conditions used for the proofs of stability of adaptive control or control with uncertainty by showing that the not necessarily symmetric CB is only required to have a diagonal Jordan form and positive eigenvalues. The paper also shows that under the new condition any minimum-phase systems can be made strictly positive real via constant output feedback. The paper illustrates the usefulness of these extended properties with an adaptive control example. (C) 2006 Elsevier Ltd. All rights reserved.

CONTROL OF UNCERTAIN DYNAMIC-SYSTEMS USING STRICTLY POSITIVE REAL SYSTEMS

This paper presents necessary and sufficient conditions to turn a linear time-invariant system with p outputs, m inputs, p greater-than-or-equal-to m and using only inputs and outputs measurements into a Strictly Positive Real (SPR).Two results are presented. In the first, the system compensation is made by two static compensators, one of which forward feeds the outputs and the second back feeds the outputs of the nominal system.The second result presents conditions for the Walcott and Zak variable structure observer-controller synthesis. In this problem, if the nominal system is given by {A,B,C}, then the compensated system is given by {A+GC,B,FC} where F and G are the constant compensation matrices. These results are useful in the control system with uncertainties.

Comparative study of LMI-based output feedback spr synthesis for plants with different numbers of inputs and outputs

New Linear Matrix Inequalities (LMI) conditions are proposed for the following problem, called Strictly Positive Real (SPR) synthesis: given a linear time-invariant plant, find a constant output feedback matrix Ko and a constant output tandem matrix F for the controlled system to be SPR. It is assumed that the plant has the number of outputs greater than the number of inputs. Some sufficient conditions for the solution of the problem are presented and compared. These results can be directly applied in the LMI-based design of Variable Structure Control (VSC) of uncertain plants. ©2008 IEEE.

Robust controller design of a wheelchair mobile via LMI approach to SPR systems with feedback output

This article discusses the design of robust controller applied to Wheelchair Furniture via Linear Matrix Inequalities (LMI), to obtain Strictly Positive Real (SPR) systems. The contributions of this work were the choice of a mathematical model for wheelchair: mobile with uncertainty about the position of the center of gravity (CG), the decoupling of the kinematic and dynamical systems, linearization of the models, the headquarters building of parametric uncertainties, the proposal of the control loop and control law with a specified decay rate.

HPV clearance in postpartum period of HIV-positive and negative women: a prospective follow-up study

Abstract Background HPV persistence is a key determinant of cervical carcinogenesis. The influence of postpartum on HPV clearance has been debated. This study aimed to assess HPV clearance in later pregnancy and postpartum among HIV-positive and negative women. Methods We conducted a follow-up study with 151 HPV-positive women coinfected with HIV, in 2007–2010. After baseline assessment, all women were retested for HPV infection using PCR in later pregnancy and after delivery. Multivariable logistic regressions assessed the putative association of covariates with HPV status in between each one of the successive visits. Results Seventy-one women (47%) have eliminated HPV between the baseline visit and their second or third visits. HIV-positive women took a significantly longer time (7.0 ± 3.8 months) to clear HPV, compared to those not infected by HIV (5.9 ± 3.0 months). HPV clearance was significantly more likely to take place after delivery than during pregnancy (84.5% x 15.5%). Conclusions Both HIV-positive and negative women presented a significant reduction in HPV infection during the postpartum period. HIV-positive status was found to be associated with a longer period of time to clear HPV infection in pregnant women.

Functional lateralization of the anterior insula during feedback processing

Effective adaptive behavior rests on an appropriate understanding of how much responsibility we have over outcomes in the environment. This attribution of agency to ourselves or to an external event influences our behavioral and affective response to the outcomes. Despite its special importance to understanding human motivation and affect, the neural mechanisms involved in self-attributed rewards and punishments remain unclear. Previous evidence implicates the anterior insula (AI) in evaluating the consequences of our own actions. However, it is unclear if the AI has a general role in feedback evaluation (positive and negative) or plays a specific role during error processing. Using functional magnetic resonance imaging and a motion prediction task, we investigate neural responses to self- and externally attributed monetary gains and losses. We found that attribution effects vary according to the valence of feedback: significant valence × attribution interactions in the right AI, the anterior cingulate cortex (ACC), the midbrain, and the right ventral putamen. Self-attributed losses were associated with increased activity in the midbrain, the ACC and the right AI, and negative BOLD response in the ventral putamen. However, higher BOLD activity to self-attributed feedback (losses and gains) was observed in the left AI, the thalamus, and the cerebellar vermis. These results suggest a functional lateralization of the AI. The right AI, together with the midbrain and the ACC, is mainly involved in processing the salience of the outcome, whereas the left is part of a cerebello-thalamic-cortical pathway involved in cognitive control processes important for subsequent behavioral adaptations.

Laminar distribution of ballooned neurons and tau positive neurons with inclusions in patients with corticobasal degeneration

The laminar distribution of ballooned neurons (BN) and tau positive neurons with inclusions (tau+ neurons) was studied in the frontal and temporal cortex in twelve patients with corticobasal degeneration (CBD). In the majority of brain areas, the density of BN and tau+ neurons was maximal in the lower and upper cortical laminae respectively. The densities of tau+ neurons in the upper and lower cortex were positively correlated. In the majority of brain areas, however, no correlations were observed between the densities of BN and tau+ neurons. The laminar distribution of the BN may reflect the degeneration of the feedback cortico-cortical and/or the efferent cortical pathways. By contrast, the distribution of the tau+ neurons may reflect the degeneration of the feed-forward cortico-cortical pathways. In addition, BN and tau+ neurons may arise as a result of distinct pathological processes.

The construction and negotiation of identity and face in post observation feedback

Identity influences the practice of English language teachers and supervisors, their professional development and their ability to incorporate innovation and change. Talk during post observation feedback meetings provides participants with opportunities to articulate, construct, verify, contest and negotiate identities, processes which often engender issues of face. This study examines the construction and negotiation of identity and face in post observation feedback meetings between in-service English language teachers and supervisors at a tertiary institution in the United Arab Emirates. Within a linguistic ethnography framework, this study combined linguistic microanalysis of audio recorded feedback meetings with ethnographic data gathered from participant researcher knowledge, pre-analysis interviews and post-analysis participant interpretation interviews. Through a detailed, empirical description of situated ‘real life’ institutional talk, this study shows that supervisors construct identities involving authority, power, expertise, knowledge and experience while teachers index identities involving experience, knowledge and reflection. As well as these positive valued identities, other negative, disvalued identities are constructed. Identities are shown to be discursively claimed, verified, contested and negotiated through linguistic actions. This study also shows a link between identity and face. Analysis demonstrates that identity claims verified by an interactional partner can lead to face maintenance or support. However, a contested identity claim can lead to face threat which is usually managed by facework. Face, like identity, is found to be interactionally achieved and endogenous to situated discourse. Teachers and supervisors frequently risk face threat to protect their own identities, to contest their interactional partner’s identities or to achieve the feedback meeting goal i.e. improved teaching. Both identity and face are found to be consequential to feedback talk and therefore influence teacher development, teacher/supervisor relationships and the acceptance of feedback. Analysis highlights the evaluative and conforming nature of feedback in this context which may be hindering opportunities for teacher development.

Searching for the Holy Grail of International Education: Feedback from Hospitality Management Study Abroad Participants

This article reports on a study done among hospitality management students who participated in study abroad programs between January 2001 and May 2003. The participants in the study were both incoming students to the US and outgoing students from the US. The study investigates, among other things, why they had decided to study abroad, why they had selected a particular institution, how their home institution compared to the partner institution abroad, and what they perceived to be the benefits and relevance of their international experiences. It was found that respondents were generally very positive about the study abroad experience. Some interesting differences of opinion were found when the perceptions of the incoming students were compared to those of the outgoing students. The results of this study may be of particular interest to hospitality management administrators and faculty who create and administer international exchange programs.

Screening for Sexual Trauma, Intimate Partner Violence and Mental Health Symptoms among HIV Positive South African Women

Background: The psychological sequelae of sexual trauma and physical intimate partner violence (IPV) exposure can lead to poor HIV care outcomes, including poor treatment adherence. This study aimed to estimate the prevalence of and factors associated with mental health symptoms and trauma among HIV positive women. Additionally, the study aimed to assess the feasibility and acceptability of screening for trauma and mental health symptoms among HIV positive South African women. Finally, the study aimed to elicit healthcare workers’ perceptions related to sexual trauma and the provision of care and services for HIV positive women with trauma histories.

Methods: The study utilized a mixed-methods approach that included a cross-sectional survey of 70 HIV positive women recruited through referral sampling and key informant interviews with seven healthcare workers (HCWs). A study-screening instrument consisting of 24 items from standard measures was used to screen women for sexual trauma, physical intimate partner violence (IPV), depression and PTSD. Sexual trauma and IPV were assessed across the lifetime, while depression and PTSD were current assessments. Logistic regression models were used to explore the relationship between trauma exposure and mental health symptoms, while controlling for age and education. Interview transcripts were coded and analyzed for emergent themes on HCWs perceptions on sexual trauma and HIV care.

Results: Among participants, 51% had sexual trauma experience and 75% had intimate partner violence (IPV) experience. Among participants, 36% met screening criteria for major depression; among those with traumatic experiences (n=57), 70% met screening criteria for post-traumatic stress disorder (PTSD). Compared to having no sexual trauma or IPV exposure, having both sexual trauma and IPV was significantly associated with higher odds of depression (OR = 8.11; 95% CI 1.48-44.34), while having either IPV or sexual trauma individually was not significantly associated with increased odds of depression. Compared to having either IPV or sexual trauma, having both sexual trauma and IPV was not significantly associated with PTSD. Responses from participants’ feedback on screening process suggest that screening was feasible and acceptable to participants. Some of the health care workers (HCWs) did not perceive dealing with trauma to be part of their duties, but instead viewed social workers or psychologists as the appropriate health cadre to provide care related to trauma and mental health.

Conclusions: High levels of sexual trauma, IPV and mental health distress were reported among HIV positive women in this setting. Screening for trauma and mental health symptoms was acceptable to the participants, but several challenges were encountered in implementing screening. Given the potential impact of trauma and mental health on HIV care engagement, interventions to address trauma and its psychological sequelae are needed.

Does video feedback analysis improve CPR performance in phase 5 medical students?

Background The use of simulation in medical education is increasing, with students taught and assessed using simulated patients and manikins. Medical students at Queen’s University of Belfast are taught advanced life support cardiopulmonary resuscitation as part of the undergraduate curriculum. Teaching and feedback in these skills have been developed in Queen’s University with high-fidelity manikins. This study aimed to evaluate the effectiveness of video compared to verbal feedback in assessment of student cardiopulmonary resuscitation performance Methods Final year students participated in this study using a high-fidelity manikin, in the Clinical Skills Centre, Queen’s University Belfast. Cohort A received verbal feedback only on their performance and cohort B received video feedback only. Video analysis using ‘StudioCode’ software was distributed to students. Each group returned for a second scenario and evaluation 4 weeks later. An assessment tool was created for performance assessment, which included individual skill and global score evaluation. Results One hundred thirty eight final year medical students completed the study. 62 % were female and the mean age was 23.9 years. Students having video feedback had significantly greater improvement in overall scores compared to those receiving verbal feedback (p = 0.006, 95 % CI: 2.8–15.8). Individual skills, including ventilation quality and global score were significantly better with video feedback (p = 0.002 and p < 0.001, respectively) when compared with cohort A. There was a positive change in overall score for cohort B from session one to session two (p < 0.001, 95 % CI: 6.3–15.8) indicating video feedback significantly benefited skill retention. In addition, using video feedback showed a significant improvement in the global score (p < 0.001, 95 % CI: 3.3–7.2) and drug administration timing (p = 0.004, 95 % CI: 0.7–3.8) of cohort B participants, from session one to session two. Conclusions There is increased use of simulation in medicine but a paucity of published data comparing feedback methods in cardiopulmonary resuscitation training. Our study shows the use of video feedback when teaching cardiopulmonary resuscitation is more effective than verbal feedback, and enhances skill retention. This is one of the first studies to demonstrate the benefit of video feedback in cardiopulmonary resuscitation teaching.

Discrete-time positive periodic systems with state and control constraints

The aim of this paper is to provide an efficient control design technique for discrete-time positive periodic systems. In particular, stability, positivity and periodic invariance of such systems are studied. Moreover, the concept of periodic invariance with respect to a collection of boxes is introduced and investigated with connection to stability. It is shown how such concept can be used for deriving a stabilizing state-feedback control that maintains the positivity of the closed-loop system and respects states and control signals constraints. In addition, all the proposed results can be efficiently solved in terms of linear programming.

The Effects of Systematic Self-Monitoring, Feedback, and Collaborative Assessment on Stress Reduction

Thesis (Ph.D.)--University of Washington, 2016-08