Homotopical decompositions of simplicial and Vietoris Rips complexes

Motivated by applications in Topological Data Analysis, we consider decompositions of a simplicial complex induced by a cover of its vertices. We study how the homotopy type of such decompositions approximates the homotopy of the simplicial complex itself. The difference between the simplicial complex and such an approximation is quantitatively measured by means of the so called obstruction complexes. Our general machinery is then specialized to clique complexes, Vietoris-Rips complexes and Vietoris-Rips complexes of metric gluings. For the latter we give metric conditions which allow to recover the first and zero-th homology of the gluing from the respective homologies of the components

Shift: A Zero FLOP, Zero Parameter Alternative to Spatial Convolutions

Neural networks rely on convolutions to aggregate spatial information. However, spatial convolutions are expensive in terms of model size and computation, both of which grow quadratically with respect to kernel size. In this paper, we present a parameter-free, FLOP-free "shift" operation as an alternative to spatial convolutions. We fuse shifts and point-wise convolutions to construct end-to-end trainable shift-based modules, with a hyperparameter characterizing the tradeoff between accuracy and efficiency. To demonstrate the operation's efficacy, we replace ResNet's 3x3 convolutions with shift-based modules for improved CIFAR10 and CIFAR100 accuracy using 60% fewer parameters; we additionally demonstrate the operation's resilience to parameter reduction on ImageNet, outperforming ResNet family members. We finally show the shift operation's applicability across domains, achieving strong performance with fewer parameters on classification, face verification and style transfer.Comment: Source code will be released afterward

The effects of owning a pet on self-esteem and self-efficacy of Malaysian per owners

In this research, 200 pet owners and non-pet owners were studied to ascertain the effects of owning a pet on the self-esteem and self-efficacy of the pet owners. All the respondents completed self-reported questionnaires. While the results showed no significant differences, it was noted that there was a tendency for people with pets to generally have slightly higher self-esteem and self-efficacy as compared to people without pets. The study also showed that higher self-esteem contributed towards predicting higher self-efficacy

Concealment of Potential Exposure to COVID-19 and Its Impact on Outbreak Control: Lessons from the HIV Response.

Globally, more than 4 million people have been infected with COVID-19, and more than 300,000 deaths have been reported across 188 countries. Concealment of one's potential exposure to the virus has negative implications for the spread of COVID-19 across the socio-ecological spectrum, including the futility of contact-tracing efforts, exposure of frontline staff, and the spread of COVID-19 in the community. We draw lessons learned from HIV to discuss stigma and the attribution of blame surrounding the phenomenon of concealment of one's potential exposure to COVID-19 using a socio-ecological perspective. This article also illustrates the psychosocial aspect of the disease, and the negative repercussions of concealment of potential exposure on transmission in the community and to front-liners, healthcare resources, and outbreak containment

Atomic-scale characterization of mature HIV-1 capsid stabilization by inositol hexakisphosphate (IP₆)

Inositol hexakisphosphates (IP6) are cellular cofactors that promote the assembly of mature capsids of HIV. These negatively charged molecules coordinate an electropositive ring of arginines at the center of pores distributed throughout the capsid surface. Kinetic studies indicate that the binding of IP6 increases the stable lifetimes of the capsid by several orders of magnitude from minutes to hours. Using all-atom molecular dynamics simulations, we uncover the mechanisms that underlie the unusually high stability of mature capsids in complex with IP6. We find that capsid hexamers and pentamers have differential binding modes for IP6. Ligand density calculations show three sites of interaction with IP6 including at a known capsid inhibitor binding pocket. Free energy calculations demonstrate that IP6 preferentially stabilizes pentamers over hexamers to enhance fullerene modes of assembly. These results elucidate the molecular role of IP6 in stabilizing and assembling the retroviral capsid

Differential effect of clomipramine on habituation and prepulse inhibition in dominant versus subordinate rats.

Many patients with depression have comorbidities associated with an impairment of sensorimotor gating, such as e.g. schizophrenia, Parkinson Disease, or Alzheimer disease. Anti-depressants like clomipramine that modulate serotonergic or norepinephrinergic neurotransmission have been shown to impact sensorimotor gating, it is therefore important to study potential effects of clomipramine in order to rule out an exacerbation of sensorimotor gating impairment. Prior studies in animals and humans have been inconclusive. Since serotonin and norepinephrine levels are closely related to anxiety and stress levels and therefore to the social status of an animal, we tested the hypothesis that acute and chronic effects of clomipramine on sensorimotor gating are different in dominant versus subordinate rats, which might be responsible for conflicting results in past animal studies. We used habituation and prepulse inhibition (PPI) of the acoustic startle response as operational measures of sensorimotor gating. After establishing the dominant animal in pair-housed male rats, we injected clomipramine for two weeks and measured acute effects on baseline startle, habituation and PPI after the first injection and chronic effects at the end of the two weeks. Chronic treatment with clomipramine significantly increased habituation in subordinate rats, but had no effect on habituation in dominant animals. Furthermore, PPI was slightly enhanced in subordinate rats upon chronic treatment while no changes occurred in dominant animals. We conclude that the social status of an animal, and therefore the basic anxiety/stress level determines whether or not clomipramine has a beneficial effect on sensorimotor gating and discuss possible underlying mechanisms