638 research outputs found
Science is perception: what can our sense of smell tell us about ourselves and the world around us?
Human sensory processes are well understood: hearing, seeing, perhaps even tasting and touch—but we do not understand smell—the elusive sense. That is, for the others we know what stimuli causes what response, and why and how. These fundamental questions are not answered within the sphere of smell science; we do not know what it is about a molecule that … smells. I report, here, the status quo theories for olfaction, highlighting what we do not know, and explaining why dismissing the perception of the input as ‘too subjective’ acts as a roadblock not conducive to scientific inquiry. I outline the current and new theory that conjectures a mechanism for signal transduction based on quantum mechanical phenomena, dubbed the ‘swipe card’, which is perhaps controversial but feasible. I show that such lines of thinking may answer some questions, or at least pose the right questions. Most importantly, I draw links and comparisons as to how better understanding of how small (10’s of atoms) molecules can interact so specially with large (10 000’s of atoms) proteins in a way that is so integral to healthy living. Repercussions of this work are not just important in understanding a basic scientific tool used by us all, but often taken for granted, it is also a step closer to understanding generic mechanisms between drug and receptor, for example
Immunology of the canine eye in health and disease: A concise review
The canine eye is an immune-privileged organ that is provided with systems to prevent and control
the local immune response, which could have a detrimental impact. The entry of blood-derived antigens is hindered
by the blood-ocular barriers and potential invading pathogens are tackled by local antimicrobial molecules.
Despite the existence of numerous immune-competent cells, the anterior chamber of the eye is characterised by
low responsiveness. This review is focused on the innate and adaptive immunity employed to control health and
disease in the canine eye
Current and noise expressions for radio-frequency single-electron transistors
We derive self-consistent expressions of current and noise for
single-electron transistors driven by time-dependent perturbations. We take
into account effects of the electrical environment, higher-order co-tunneling,
and time-dependent perturbations under the two-charged state approximation
using the Schwinger-Kedysh approach combined with the generating functional
technique. For a given generating functional, we derive exact expressions for
tunneling currents and noises and present the forms in terms of transport
coefficients. It is also shown that in the adiabatic limit our results
encompass previous formulas. In order to reveal effects missing in static
cases, we apply the derived results to simulate realized radio-frequency
single-electron transistor. It is found that photon-assisted tunneling affects
largely the performance of the single-electron transistor by enhancing both
responses to gate charges and current noises. On various tunneling resistances
and frequencies of microwaves, the dependence of the charge sensitivity is also
discussed.Comment: 18 pages, 9 figure
Could humans recognize odor by phonon assisted tunneling?
Our sense of smell relies on sensitive, selective atomic-scale processes that
are initiated when a scent molecule meets specific receptors in the nose.
However, the physical mechanisms of detection are not clear. While odorant
shape and size are important, experiment indicates these are insufficient. One
novel proposal suggests inelastic electron tunneling from a donor to an
acceptor mediated by the odorant actuates a receptor, and provides critical
discrimination. We test the physical viability of this mechanism using a simple
but general model. Using values of key parameters in line with those for other
biomolecular systems, we find the proposed mechanism is consistent both with
the underlying physics and with observed features of smell, provided the
receptor has certain general properties. This mechanism suggests a distinct
paradigm for selective molecular interactions at receptors (the swipe card
model): recognition and actuation involve size and shape, but also exploit
other processes.Comment: 10 pages, 1 figur
Correlation between bicuspid aortic valve fusion phenotype and aortic arch morphology using MRI
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