The ventro-lateral pulvinar is reciprocally connected with the visual areas of the ventral stream that are important for object recognition. To understand the mechanisms of attentive stimulus ...processing in this pulvinar-cortex loop, we investigated the interactions between the pulvinar, area V4, and IT cortex in a spatial-attention task. Sensory processing and the influence of attention in the pulvinar appeared to reflect its cortical inputs. However, pulvinar deactivation led to a reduction of attentional effects on firing rates and gamma synchrony in V4, a reduction of sensory-evoked responses and overall gamma coherence within V4, and severe behavioral deficits in the affected portion of the visual field. Conversely, pulvinar deactivation caused an increase in low-frequency cortical oscillations, often associated with inattention or sleep. Thus, cortical interactions with the ventro-lateral pulvinar are necessary for normal attention and sensory processing and for maintaining the cortex in an active state.
•Neuronal properties and attentional modulation are similar in pulvinar and V4•V4 leads pulvinar in gamma synchrony during attentive stimulus processing•Pulvinar deactivation reduces both sensory response and attentional effect in V4•Following pulvinar deactivation, cortex appears to go to an inactive state
The pulvinar is often proposed to modulate cortical processing with attention. Zhou et al. find that beyond any role in attention, the pulvinar input to cortex seems necessary to maintain the cortex in an active state.
For centuries, thinking about the earth's increasing human
population has been tied to environmental ideas and political
action. This highly teachable collection of contextualized primary
sources ...allows students to follow European and North American
discussions about intertwined and evolving concepts of population,
resources, and the natural environment from early contexts in the
sixteenth century right through to the present day.
Edited and introduced by Robert J. Mayhew, a noted biographer of
Thomas Robert Malthus-whose Essay on the Principle of
Population (1798), excerpted here, is an influential and
controversial take on the topic-this volume explores themes
including evolution, eugenics, war, social justice, birth control,
environmental Armageddon, and climate change. Other responses to
the idea of new "population bombs" are represented here by radical
feminist work, by Indigenous views of the population-environment
nexus, and by intersectional race-gender approaches. By learning
the patterns of this discourse, students will be better able to
critically evaluate historical conversations as well as
contemporary debates.
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•The global picture of chemical pollution in the environment is often fragmented.•This perspective highlights global picture of pollution regarding catastrophic risk.•Exposure related ...impact on fertility, cognition and food safety are discussed.•Prioritised strategies for curbing chemical dispersal are recommended.
Anthropogenic chemical pollution has the potential to pose one of the largest environmental threats to humanity, but global understanding of the issue remains fragmented. This article presents a comprehensive perspective of the threat of chemical pollution to humanity, emphasising male fertility, cognitive health and food security. There are serious gaps in our understanding of the scale of the threat and the risks posed by the dispersal, mixture and recombination of chemicals in the wider environment. Although some pollution control measures exist they are often not being adopted at the rate needed to avoid chronic and acute effects on human health now and in coming decades. There is an urgent need for enhanced global awareness and scientific scrutiny of the overall scale of risk posed by chemical usage, dispersal and disposal.
Alpha-cut representation of fuzzy sets has been used as a basis for fuzzy numbers ranking in some applications but rarely used for defuzzification of rule-based systems or fuzzy controllers. ...Moreover, such alpha-cut defuzzification (called ACD here) is not yet formally linked to the membership function (MF) or to the common MF-based defuzzification methods, namely the centroid. The ACD can be considered as a generalisation of the similar algorithms in fuzzy numbers to any fuzzy set. A close-form formula for ACD is developed that involves both MF and its derivative, which shows that ACD reflects both static and dynamic aspects of a fuzzy set. Moreover, formal links between ACD and some MF-based defuzzification methods are shown. Through two groups of experiments, the utility of the new method is compared with centroid defuzzification. Particularly, we examined how the ACD significantly outperforms the centroid for noisy time-series prediction. Finally, the computation complexity of ACD is shown to be about the same as the centroid method, for convex fuzzy sets. Our tests suggest that ACD can be considered as a viable alternative defuzzification method for fuzzy system designers.
On 24 May 1966, eight hundred men of the 5th Battalion, The Royal Australian Regiment, landed at Nui Dat, in Viet Cong territory. For the next 12 months they were faced with the task of restoring ...peace, civil law and regular commerce to the Vietnamese of Phuoc Tuy province. This book is a detailed record of those months in the monsoon jungles—of the problems that were faced and the solutions that were found. Captain O’Neill’s position as battalion intelligence officer enabled him to view the war from the standpoint of the battalion as a whole. However, he does not omit description of personal feelings—towards the Viet Cong, the jungle environment and the Vietnamese people, as well as the other Allied forces involved in the war. Most of the book was written on the spot in Vietnam. On operations or at Battalion Headquarters, Captain O’Neill jotted down details of the war against the Viet Cong, putting the events of each day in order, often in the small hours of the following morning. Thus not only is this a factual account of the 5th Battalion’s activities over the year; it is also a vivid and compelling picture of the war in Vietnam from the soldier’s point of view.
•Bond of deformed steel bars in NAC and RAC is investigated.•Pullout tests were carried out on 12, 16, 20 and 25mm bars.•Bond failure mode in NAC and RAC has been compared.•Measured bond strength has ...been calibrated with codal predictions.•Empirical bond–slip relationship has been proposed for the RAC and the NAC.
The results of sixty pullout tests carried out using 12mm, 16mm, 20mm and 25mm diameter deformed steel bars concentrically embedded in recycled aggregate concrete designed using equivalent mix proportions with coarse recycled concrete aggregate (RCA) replacement levels of 0%, 25%, 50%, 75% and 100% are reported towards investigation of bond behaviour of RCA concrete. It is postulated that due to internal curing action of the RCA particles, the relative bond strengths, obtained by normalising the measured bond stress with the respective compressive strength of concrete, across all the RCA replacement levels were higher for the RCA concrete compared to the NCA concrete. Further, the relative bond strengths increased with RCA replacement levels and the highest values were obtained for 100% replacement of natural coarse aggregate with RCA. On the basis of a regression analysis of the experimental data, an empirical bond stress-versus-slip relationship between RCA concrete and deformed steel bars has been proposed and it has been conservatively suggested that anchorage lengths of 12mm, 16mm, 20mm and 25mm diameter deformed steel bars embedded in RCA concrete may be taken to be the same as that in natural aggregate concrete.
Attention can be “covertly” directed without eye movements; yet, even during fixation, there are continuous microsaccades (MSs). In areas V4 and IT of macaques, we found that firing rates and ...stimulus representations were enhanced by attention but only following a MS toward the attended stimulus. The onset of neural attentional modulations was tightly coupled to the MS onset. The results reveal a major link between the effects of covert attention on cortical visual processing and the overt movement of the eyes.
•Attentional modulation in V4 emerges only after microsaccades toward the stimulus•Onset of attention modulations is coupled to microsaccade onset•Object decoding is enhanced in V4 and IT after microsaccades toward the cued stimulus•Linkage between attention modulation and microsaccades is extra-retinal
Attention can be “covertly” directed without eye movements; yet, even during fixation, there are microsaccades. We found that neural activity was enhanced by attention, but only following a microsaccade toward the stimulus, revealing a major link between covert attention and the oculomotor system.
Over the past half a century many countries have witnessed a rapid fall in total fertility rates, particularly in the world's most advanced economies including the industrial powerhouses of Eastern ...Asia and Europe. Such nations have now passed through the first and second demographic transitions and are currently exhibiting fertility rates well below the replacement threshold of 2.1, with no sign of recovery. This paper examines the factors responsible for driving these demographic transitions and considers their impact on both fertility and fecundity (our fundamental capacity to reproduce). I argue that because the first demographic transition was extremely rapid and largely driven by socioeconomic factors, it has had no lasting impact on the genetic/epigenetic underpinnings of human fecundity. However, the second demographic transition will be different. A series of conditions associated with low fertility societies, including relaxed selection pressure for high-fertility genotypes, the indiscriminate use of assisted reproductive technologies to treat human infertility, and environmental contamination with reproductive toxicants, may impact our genetic constitution in ways that compromise the future fecundity of our species. Since any fundamental change in the genetic foundations of human reproduction will be difficult to reverse, we should actively pursue methods to monitor human fecundity, as sub-replacement fertility levels become established across the globe.
Hyperphosphorylated tau has a critical role in tauopathies such as Alzheimer’s disease and frontotemporal dementia, impairing neuronal function and eventually leading to neurodegeneration. A critical ...role for tau is supported by studies in transgenic mouse models that express the P301L tau mutation found in cases of familial frontotemporal dementia, with the accumulation of hyperphosphorylated tau in the hippocampus causing reductions in hippocampal long-term potentiation and impairments in spatial learning and memory. However, what has remained unexplored is the role of hyperphosphorylated tau in reducing neuronal excitability. Here, we show in two complementary P301L tau transgenic mouse models that hyperphosphorylated tau induces a more depolarized threshold for action potential initiation and reduces firing in hippocampal CA1 neurons, which was rescued by the suppression of transgenic tau. Furthermore, using mutagenesis and primary hippocampal neuronal cultures, we reveal that this reduction in neuronal excitability results from the relocation of the axon initial segment (AIS) down the axon in a tau phosphorylation-dependent manner. We also demonstrate that this effect is microtubule-dependent. In addition, pharmacological stabilization was found to prevent both the structural and functional deficits caused by tau hyperphosphorylation. Finally, we demonstrate that the AIS of neurons from tau transgenic mice is further down the axon, which correlates with a reduction in excitability. We therefore propose that a reduction in hippocampal excitability due to a tau-mediated distal relocalization of the AIS contributes to the hippocampal dysfunction observed in tauopathies.
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