Spatial representation in blindness

The role of previous visual experience in relation to spatial representation is investigated by comparing the performance of the congenitally blind, the late-blinded and the sighted blindfolded on a number, of near-space tasks involving mental rotation, mental manipulation and scale transformation, and a far-space task involving the representation of two routes by means of pointing, drawing and the making of spatial inferences. In relation to the former, the role of visual imagery in assisting performance is seriously questioned as accounting for the inferiority of the congenitally blind compared to the late-blinded and the sighted, since scores on a visual imagery test administered to the latter group failed to correlate positively with task performance. However . the poor tactual exploratory strategies observed in the congenitally blind would account for their poor performance on a variety of spatial recognition tasks. In relation to the latter, the congenitally blind tended to perform in a qualitatively different manner to the late-blinded and the sighted blindfolded in all aspects of the task, in addition to performing at a much poorer level than the other groups. Gross errors were found to be due to varying degrees of "egocentric' or 1%se lf-referent' spatial coding strategies inappropriate to such a task. A validation and reliability methodology successfully developed for analysing drawings in the sighted could only be applied to one congenitally blind subject's drawings, the remainder being highly idiosyncratic. The role of previous visual experience in drawing attention to simultaneously existent spatial locations is discussed, and the importance of training the congenitally blind to explore tactual stimuli in a systematic and exhaustive manner, and also to pay attention to external spatial cues is emphasised as being essential for successful mobility and the use of tactual maps

Spatial representation in blindness

The role of previous visual experience in relation to spatial representation is investigated by comparing the performance of the congenitally blind, the late-blinded and the sighted blindfolded on a number, of near-space tasks involving mental rotation, mental manipulation and scale transformation, and a far-space task involving the representation of two routes by means of pointing, drawing and the making of spatial inferences. In relation to the former, the role of visual imagery in assisting performance is seriously questioned as accounting for the inferiority of the congenitally blind compared to the late-blinded and the sighted, since scores on a visual imagery test administered to the latter group failed to correlate positively with task performance. However . the poor tactual exploratory strategies observed in the congenitally blind would account for their poor performance on a variety of spatial recognition tasks. In relation to the latter, the congenitally blind tended to perform in a qualitatively different manner to the late-blinded and the sighted blindfolded in all aspects of the task, in addition to performing at a much poorer level than the other groups. Gross errors were found to be due to varying degrees of "egocentric' or 1%se lf-referent' spatial coding strategies inappropriate to such a task. A validation and reliability methodology successfully developed for analysing drawings in the sighted could only be applied to one congenitally blind subject's drawings, the remainder being highly idiosyncratic. The role of previous visual experience in drawing attention to simultaneously existent spatial locations is discussed, and the importance of training the congenitally blind to explore tactual stimuli in a systematic and exhaustive manner, and also to pay attention to external spatial cues is emphasised as being essential for successful mobility and the use of tactual maps

Numerical investigation of 3-D constraint effects on brittle fracture in SE(B) and C(T) specimens

This investigation employs 3-D nonlinear finite element analyses to conduct an extensive parametric evaluation of crack front stress triaxiality for deep notch SE(B) and C(T) specimens and shallow notch SE(B) specimens, with and without side grooves. Crack front conditions are characterized in terms of J-Q trajectories and the constraint scaling model for cleavage fracture toughness proposed previously by Dodds and Anderson. The 3-D computational results imply that a significantly less strict size/deformation limit, relative to the limits indicated by previous plane-strain computations, is needed to maintain small-scale yielding conditions at fracture by a stress- controlled, cleavage mechanism in deep notch SE(B) and C(T) specimens. Additional new results made available from the 3-D analyses also include revised {eta}-plastic factors for use in experimental studies to convert measured work quantities to thickness average and maximum (local) J-values over the crack front

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease