7 research outputs found
Thinking Outside the Euclidean Box: Riemannian Geometry and Inter-Temporal Decision-Making
<div><p>Inter-temporal decisions involves assigning values to various payoffs occurring at different temporal distances. Past research has used different approaches to study these decisions made by humans and animals. For instance, considering that people discount future payoffs at a constant rate (e.g., exponential discounting) or at variable rate (e.g., hyperbolic discounting). In this research, we question the widely assumed, but seldom questioned, notion across many of the existing approaches that the decision space, where the decision-maker perceives time and monetary payoffs, is a Euclidean space. By relaxing the rigid assumption of Euclidean space, we propose that the decision space is a more flexible Riemannian space of Constant Negative Curvature. We test our proposal by deriving a discount function, which uses the distance in the Negative Curvature space instead of Euclidean temporal distance. The distance function includes both perceived values of time as well as money, unlike past work which has considered just time. By doing so we are able to explain many of the empirical findings in inter-temporal decision-making literature. We provide converging evidence for our proposal by estimating the curvature of the decision space utilizing manifold learning algorithm and showing that the characteristics (i.e., metric properties) of the decision space resembles those of the Negative Curvature space rather than the Euclidean space. We conclude by presenting new theoretical predictions derived from our proposal and implications for how non-normative behavior is defined.</p></div
El Diario de Pontevedra : periódico liberal: Ano XXVIII Número 8177 - 1911 agosto 16
Omniphobic
surfaces, that is, which repel all known liquids, have
proven of value in applications ranging from membrane distillation
to underwater drag reduction. A limitation of currently employed omniphobic
surfaces is that they rely on perfluorinated coatings, increasing
cost and environmental impact and preventing applications in harsh
environments. Thus, there is a keen interest in rendering conventional
materials, such as plastics, omniphobic by micro/nanotexturing rather
than via chemical makeup, with notable success having been achieved
for silica surfaces with doubly reentrant micropillars. However, we
found a critical limitation of microtextures comprising pillars that
they undergo catastrophic wetting transitions (apparent contact angles,
θ<sub>r</sub> → 0° from θ<sub>r</sub> >
90°)
in the presence of localized physical damages/defects or on immersion
in wetting liquids. In response, a doubly reentrant cavity microtexture
is introduced, which can prevent catastrophic wetting transitions
in the presence of localized structural damage/defects or on immersion
in wetting liquids. Remarkably, our silica surfaces with doubly reentrant
cavities could exhibit apparent contact angles, θ<sub>r</sub> ≈ 135° for mineral oil, where the intrinsic contact
angle, θ<sub>o</sub> ≈ 20°. Further, when immersed
in mineral oil or water, doubly reentrant microtextures in silica
(θ<sub>o</sub> ≈ 40° for water) were not penetrated
even after several days of investigation. Thus, microtextures comprising
doubly reentrant cavities might enable applications of conventional
materials without chemical modifications, especially in scenarios
that are prone to localized damages or immersion in wetting liquids,
for example, hydrodynamic drag reduction and membrane distillation
Doubly Reentrant Cavities Prevent Catastrophic Wetting Transitions on Intrinsically Wetting Surfaces
Omniphobic
surfaces, that is, which repel all known liquids, have
proven of value in applications ranging from membrane distillation
to underwater drag reduction. A limitation of currently employed omniphobic
surfaces is that they rely on perfluorinated coatings, increasing
cost and environmental impact and preventing applications in harsh
environments. Thus, there is a keen interest in rendering conventional
materials, such as plastics, omniphobic by micro/nanotexturing rather
than via chemical makeup, with notable success having been achieved
for silica surfaces with doubly reentrant micropillars. However, we
found a critical limitation of microtextures comprising pillars that
they undergo catastrophic wetting transitions (apparent contact angles,
θ<sub>r</sub> → 0° from θ<sub>r</sub> >
90°)
in the presence of localized physical damages/defects or on immersion
in wetting liquids. In response, a doubly reentrant cavity microtexture
is introduced, which can prevent catastrophic wetting transitions
in the presence of localized structural damage/defects or on immersion
in wetting liquids. Remarkably, our silica surfaces with doubly reentrant
cavities could exhibit apparent contact angles, θ<sub>r</sub> ≈ 135° for mineral oil, where the intrinsic contact
angle, θ<sub>o</sub> ≈ 20°. Further, when immersed
in mineral oil or water, doubly reentrant microtextures in silica
(θ<sub>o</sub> ≈ 40° for water) were not penetrated
even after several days of investigation. Thus, microtextures comprising
doubly reentrant cavities might enable applications of conventional
materials without chemical modifications, especially in scenarios
that are prone to localized damages or immersion in wetting liquids,
for example, hydrodynamic drag reduction and membrane distillation
Doubly Reentrant Cavities Prevent Catastrophic Wetting Transitions on Intrinsically Wetting Surfaces
Omniphobic
surfaces, that is, which repel all known liquids, have
proven of value in applications ranging from membrane distillation
to underwater drag reduction. A limitation of currently employed omniphobic
surfaces is that they rely on perfluorinated coatings, increasing
cost and environmental impact and preventing applications in harsh
environments. Thus, there is a keen interest in rendering conventional
materials, such as plastics, omniphobic by micro/nanotexturing rather
than via chemical makeup, with notable success having been achieved
for silica surfaces with doubly reentrant micropillars. However, we
found a critical limitation of microtextures comprising pillars that
they undergo catastrophic wetting transitions (apparent contact angles,
θ<sub>r</sub> → 0° from θ<sub>r</sub> >
90°)
in the presence of localized physical damages/defects or on immersion
in wetting liquids. In response, a doubly reentrant cavity microtexture
is introduced, which can prevent catastrophic wetting transitions
in the presence of localized structural damage/defects or on immersion
in wetting liquids. Remarkably, our silica surfaces with doubly reentrant
cavities could exhibit apparent contact angles, θ<sub>r</sub> ≈ 135° for mineral oil, where the intrinsic contact
angle, θ<sub>o</sub> ≈ 20°. Further, when immersed
in mineral oil or water, doubly reentrant microtextures in silica
(θ<sub>o</sub> ≈ 40° for water) were not penetrated
even after several days of investigation. Thus, microtextures comprising
doubly reentrant cavities might enable applications of conventional
materials without chemical modifications, especially in scenarios
that are prone to localized damages or immersion in wetting liquids,
for example, hydrodynamic drag reduction and membrane distillation
Doubly Reentrant Cavities Prevent Catastrophic Wetting Transitions on Intrinsically Wetting Surfaces
Omniphobic
surfaces, that is, which repel all known liquids, have
proven of value in applications ranging from membrane distillation
to underwater drag reduction. A limitation of currently employed omniphobic
surfaces is that they rely on perfluorinated coatings, increasing
cost and environmental impact and preventing applications in harsh
environments. Thus, there is a keen interest in rendering conventional
materials, such as plastics, omniphobic by micro/nanotexturing rather
than via chemical makeup, with notable success having been achieved
for silica surfaces with doubly reentrant micropillars. However, we
found a critical limitation of microtextures comprising pillars that
they undergo catastrophic wetting transitions (apparent contact angles,
θ<sub>r</sub> → 0° from θ<sub>r</sub> >
90°)
in the presence of localized physical damages/defects or on immersion
in wetting liquids. In response, a doubly reentrant cavity microtexture
is introduced, which can prevent catastrophic wetting transitions
in the presence of localized structural damage/defects or on immersion
in wetting liquids. Remarkably, our silica surfaces with doubly reentrant
cavities could exhibit apparent contact angles, θ<sub>r</sub> ≈ 135° for mineral oil, where the intrinsic contact
angle, θ<sub>o</sub> ≈ 20°. Further, when immersed
in mineral oil or water, doubly reentrant microtextures in silica
(θ<sub>o</sub> ≈ 40° for water) were not penetrated
even after several days of investigation. Thus, microtextures comprising
doubly reentrant cavities might enable applications of conventional
materials without chemical modifications, especially in scenarios
that are prone to localized damages or immersion in wetting liquids,
for example, hydrodynamic drag reduction and membrane distillation
Doubly Reentrant Cavities Prevent Catastrophic Wetting Transitions on Intrinsically Wetting Surfaces
Omniphobic
surfaces, that is, which repel all known liquids, have
proven of value in applications ranging from membrane distillation
to underwater drag reduction. A limitation of currently employed omniphobic
surfaces is that they rely on perfluorinated coatings, increasing
cost and environmental impact and preventing applications in harsh
environments. Thus, there is a keen interest in rendering conventional
materials, such as plastics, omniphobic by micro/nanotexturing rather
than via chemical makeup, with notable success having been achieved
for silica surfaces with doubly reentrant micropillars. However, we
found a critical limitation of microtextures comprising pillars that
they undergo catastrophic wetting transitions (apparent contact angles,
θ<sub>r</sub> → 0° from θ<sub>r</sub> >
90°)
in the presence of localized physical damages/defects or on immersion
in wetting liquids. In response, a doubly reentrant cavity microtexture
is introduced, which can prevent catastrophic wetting transitions
in the presence of localized structural damage/defects or on immersion
in wetting liquids. Remarkably, our silica surfaces with doubly reentrant
cavities could exhibit apparent contact angles, θ<sub>r</sub> ≈ 135° for mineral oil, where the intrinsic contact
angle, θ<sub>o</sub> ≈ 20°. Further, when immersed
in mineral oil or water, doubly reentrant microtextures in silica
(θ<sub>o</sub> ≈ 40° for water) were not penetrated
even after several days of investigation. Thus, microtextures comprising
doubly reentrant cavities might enable applications of conventional
materials without chemical modifications, especially in scenarios
that are prone to localized damages or immersion in wetting liquids,
for example, hydrodynamic drag reduction and membrane distillation
Protonation and Oligomerization of Gaseous Isoprene on Mildly Acidic Surfaces: Implications for Atmospheric Chemistry
In a global process linking the Earth’s climate with
its ecosystems,
massive photosynthetic isoprene (ISOP) emissions are converted to
light-scattering haze. This phenomenon is imperfectly captured
by atmospheric chemistry models: predicted ISOP emissions atop forest
canopies would deplete the oxidizing capacity of the overhead atmosphere,
at variance with field observations. Here we address this key issue
in novel laboratory experiments where we apply electrospray mass spectrometry
to detect online the products of the reactive uptake of gaseous ISOP
on the surface of aqueous jets as a function of acidity. We found
that ISOP is already protonated to ISOPH<sup>+</sup> and undergoes
cationic oligomerization to (ISOP)<sub>2</sub>H<sup>+</sup> and (ISOP)<sub>3</sub>H<sup>+</sup> on the surface of pH < 4 water jets. We estimate
uptake coefficients, γ<sub>ISOP</sub> = (0.5 – 2.0) ×
10<sup>–6</sup> on pH = 3 water, which translate into the significant
reuptake
of leaf-level ISOP emissions in typical (surface-to-volume ∼5
m<sup>–1</sup>) forests during realistic (a few minutes) in-canopy
residence
times. Our findings may also account for the rapid decay of ISOP in
forests after sunset and help bring the global budget of volatile
organic compounds closer to balance