Structural Evaluation of the Spike Glycoprotein Variants on SARS-CoV-2 Transmission and Immune Evasion

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) presents significant social, economic and political challenges worldwide. SARS-CoV-2 has caused over 3.5 million deaths since late 2019. Mutations in the spike (S) glycoprotein are of particular concern because it harbours the domain which recognises the angiotensin-converting enzyme 2 (ACE2) receptor and is the target for neutralising antibodies. Mutations in the S protein may induce alterations in the surface spike structures, changing the conformational B-cell epitopes and leading to a potential reduction in vaccine efficacy. Here, we summarise how the more important variants of SARS-CoV-2, which include cluster 5, lineages B.1.1.7 (Alpha variant), B.1.351 (Beta), P.1 (B.1.1.28/Gamma), B.1.427/B.1.429 (Epsilon), B.1.526 (Iota) and B.1.617.2 (Delta) confer mutations in their respective spike proteins which enhance viral fitness by improving binding affinity to the ACE2 receptor and lead to an increase in infectivity and transmission. We further discuss how these spike protein mutations provide resistance against immune responses, either acquired naturally or induced by vaccination. This information will be valuable in guiding the development of vaccines and other therapeutics for protection against the ongoing coronavirus disease 2019 (COVID-19) pandemic.     

Implicit theories, attributions, and coping: A meaning system approach.

This research sought to integrate C. S. Dweck and E. L. Leggett's (1988) model with attribution theory. Three studies tested the hypothesis that theories of intelligence—the belief that intelligence is malleable (incremental theory) versus fixed (entity theory)—would predict (and create) effort versus ability attributions, which would then mediate mastery-oriented coping. Study 1 revealed that, when given negative feedback, incremental theorists were more likely than entity theorists to attribute to effort. Studies 2 and 3 showed that incremental theorists were more likely than entity theorists to take remedial action if performance was unsatisfactory. Study 3, in which an entity or incremental theory was induced, showed that incremental theorists' remedial action was mediated by their effort attributions. These results suggest that implicit theories create the meaning framework in which attributions occur and are important for understanding motivation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A self-tuning ultrasonic sensor based powder injection molding process

Ultrasonic sensors show great promise in defect detection and classification when monitoring the powder injection molding (PIM) manufacturing process. To date, however, these sensors are not used in a closed-loop control system. A simplex method is developed that automatically tunes a manufacturing system operating conditions on the basis of in situ ultrasonic sensor readings. Potential applications for this system include the initial set-up of optimal manufacturing conditions and also tracking of the optimum conditions in situ during long-term operation.     

Effect of gastrostomy on growth in children with neurodevelopmental disabilities.

Chronic malnutrition and growth failure are frequent consequences of feeding difficulties in neurodevelopmentally disabled children. Gastrostomy feeding has been used successfully to alleviate chronic malnutrition as well as distress and frustration associated with feeding. Unfortunately, caregivers are often resistant to gastrostomy placement. In order to determine the impact of gastrostomies in 20 children with neurodevelopmental disability (NDD), a questionnaire was used to collect caregivers' perceptions both before and after gastrostomy. The questionnaire assessed caregivers' retrospective perceptions of quality of life, feeding difficulties, and the burdens and benefits of gastrostomies. To determine impact on growth, height and weight were measured once before and three times after gastrostomy (at six, 12, and 24 months). The number of times a child was fed and the amount of time spent feeding decreased significantly following gastrostomy (p<0.001 and p<0.05, respectively). Growth for all children improved following gastrostomy (p<0.001). Pre-gastrostomy problems improved significantly following gastrostomy, as did caregivers' perceptions of quality of life for both themselves and their child (p<0.001). These results indicate that gastrostomy has a positive impact on growth for neurodevelopmentally disabled children, and on quality of life for both children and caregivers. Caregivers may find these results encouraging if they are faced with a decision about gastrostomy placement for their child.     

When a reappearance is old news: Visual marking survives occlusion.

Performance in a visual search task becomes more efficient if half of the distractors are presented before the rest of the stimuli. This "preview benefit" may partly be due to inhibition of the old (previewed) items. The preview effect is abolished, however, if the old items offset briefly before reappearing (D. G. Watson & G. W. Humphreys, 1997). The authors examined whether this offset effect still occurred if the old item undergo occlusion. Results show that a preview benefit was found when the old items were occluded but not otherwise, consistent with the idea of top-down attentional inhibition being applied to the old items. The preview benefit is attenuated, however, by movement of the irrelevant stimuli in the displays. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual marking: Prioritizing selection for new objects by top-down attentional inhibition of old objects.

The authors propose a new mechanism for prioritizing the selection of new events: visual marking. In a modified conjunction search task the authors presented one set of distractors before the remaining items, which contained the target if present. Search was as efficient as if only the second items were presented. This held when eye movements were prevented and required a gap of 400 ms between the old and new items. The effect was abolished by luminance changes at old distractor locations when the new items appeared, and it was reduced by the addition of an attention demanding load task. The authors propose that old items can be ignored by spatially parallel, top-down attentional inhibition applied to the locations of static stimuli. The authors discuss the relations between marking and other accounts of visual selection and potential neurophysiological mechanisms. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Verifying data refinements using a model checker

In this paper, we consider how refinements between state-based specifications (e.g., written in Z) can be checked by use of a model checker. Specifically, we are interested in the verification of downward and upward simulations which are the standard approach to verifying refinements in state-based notations. We show how downward and upward simulations can be checked using existing temporal logic model checkers.In particular, we show how the branching time temporal logic CTL can be used to encode the standard simulation conditions. We do this for both a blocking, or guarded, interpretation of operations (often used when specifying reactive systems) as well as the more common non-blocking interpretation of operations used in many state-based specification languages (for modelling sequential systems). The approach is general enough to use with any state-based specification language, and we illustrate how refinements between Z specifications can be checked using the SAL CTL model checker using a small example.