1,746 research outputs found
For the Sensing of Viral DNA: An Integrated Polydimethylsiloxane Accurate CRISPR Detection (IMPACT) System
Infectious disease outbreaks have become more frequent and extreme in recent years, and as populations continue to grow and the world becomes more interconnected, they show no signs of stopping. The current COVID-19 pandemic affecting the world and grinding economies to a halt was known about months ago but could not be contained. One of the largest issues facing the containment of infectious disease is a lack of real-time, point-of-care detection devices which can accurately and effectively identify those who are infected so they can be treated and quarantined. Here, an Integrated Micropillar Polydimethylsiloxane Accurate CRISPR Detection (IMPACT) system is developed for detection of viral DNA. Single-stranded DNA reporter probes with fluorescent dyes are immobilized within the system, taking advantage of the increased surface area from the micropillar. A CRISPR-Cas12a and crRNA complex is then injected into the system, and if double-stranded target DNA is present, the CRISPR enzyme is activated and indiscriminately cleaves reporter probes, greatly increasing the fluorescent signal. The system can then be washed and the supernatant collected and measured, revealing accurate detection of the viral DNA target down to 0.1 nM concentration with no fluorescence background
Motivation for Heat Adaption: How Perception and Exposure Affect Individual Behaviors During Hot Weather in Knoxville, Tennessee
Heat is the deadliest meteorological hazard; however, those exposed to heat often do not feel they are in danger of heat-health effects and do not take precautions to avoid heat exposure. Socioeconomic factors, such as the high cost of running air conditioning, might prevent people from taking adaption measures. We assessed via a mixed-methods survey how residents of urban Knoxville, Tennessee, (n = 86) describe and interpret their personal vulnerability during hot weather. Thematic analyses reveal that many respondents describe uncomfortably hot weather based on its consequences, such as health effects and the need to change normal behavior, which misaligns with traditional heat-communication measures using specific weather conditions. Only 55% of those who perceived excessive heat as dangerous cited health as a cause for concern. Respondents who have experienced health issues during hot weather were more likely to perceive heat as dangerous and take actions to reduce heat exposure. Social cohesion was not a chief concern for our respondents, even though it has been connected to reducing time-delayed heat-health effects. Results support using thematic analyses, an underutilized tool in climatology research, to improve understanding of public perception of atmospheric hazards. We recommend a multi-faceted approach to addressing heat vulnerability
Absence of low-temperature dependence of the decay of 7Be and 198Au in metallic hosts
The electron-capture (EC) decay rate of 7Be in metallic Cu host and the
beta-decay rate of 198Au in the host alloy Al-Au have been measured
simultaneously at several temperatures, ranging from 0.350 K to 293 K. No
difference of the half-life of 198Au between 12.5 K and 293 K is observed to a
precision of 0.1%. By utilizing the special characteristics of our
double-source assembly, possible geometrical effects that influence the
individual rates could be eliminated. The ratio of 7Be to 198Au activity thus
obtained also remains constant for this temperatures range to the experimental
precision of 0.15(0.16)%. The resulting null temperature dependence is
discussed in terms of the inadequacy of the often-used Debye-Huckel model for
such measurements.Comment: Four pages, three figures. Accepted for publication in Phys. Rev. C
(Rapd Communications
Devonian Fungi: Interactions with the Green Alga Palaeonitella
This paper describes three new taxa of fossil aquatic fungi preserved in 400-million-year-old Lower Devonian Rhynie Chert. All of the fungal morphotypes are attached to cells of the green alga Palaeonitella cranii. Milleromyces rhyniensis is characterized by a holocarpic, epibiotic ^oosporangium with an elongate discharge tube that penetrates the host cell wall; arising from the base of the sporangium is an extensive rhizoidal system. Stages in infection by presumed zoospores are documented. In Lyonomyces pyriformis the globose-pyriform thallus is embedded in the surface coating of the cell wall. At
the base of each thallus is a single rhizoid. Krispiromyces is extramatrical, holocarpic, and characterized by a short beak-like discharge papilla. The rhizoidal system appears to be apophysate. Some of these fungi were probably saprobes, while others were deemed parasitic because of the extensive hypertrophy of some of the algal cells. Although not all life history stages are represented, the discovery of these Lower Devonian forms greatly expands our knowledge of the biology and diversity of aquatic fungi in an ancient freshwater ecosystem
Field-Tuning of the electron and hole populations in the ruthenate Bi_3Ru_3O_11
Experiments on the Hall coefficient R_H and heat capactity C reveal an
unusual, compensated electronic ground state in the ruthenate Bi_3Ru_3O_11. At
low temperature T, R_H decreases linearly with magnetic field |H| for fields
larger than the field scale set by the Zeeman energy. The results suggest that
the electron and hole populations are tuned by H in opposite directions via
coupling of the spins to the field. As T is decreased below 5 K, the curve
C(T)/T vs. T^2 shows an anomalous flattening consistent with a rapidly growing
Sommerfeld parameter \gamma(T). We discuss shifts of the electron and hole
chemical potentials by H to interpret the observed behavior of R_H.Comment: 5 pages, 6 figures, reference adde
Reducing Aversive Interactions with Troubled Students
This paper is about the impact of staff in-service education on the quality of interactions between staff and students at an educational facility for at-risk youth operated by the Orange County Department of Education. Data on the use of punitive behavior management techniques was gathered before, during, and after staff training in the use of more positive approaches to responding to disruptive behavior. Staff members use of punitive techniques as physical restraint and suspensions was greatly reduced following the training
Andreev reflections on Y1-xCaxBa2Cu3O7-delta evidence for an unusual proximity effect
We have measured Andreev reflections between an Au tip and
Y_{1-x}Ca_{x}Ba_{2}Cu_{3}O_{7 - \delta} thin films in the in-plane orientation.
The conductance spectra are best fitted with a pair potential having the
"d_{x^{2}-y^{2}+is" symmetry. We find that the amplitude of the "is" component
is enhanced as the contact transparency is increased. This is an indication for
an unusual proximity effect that modifies the pair potential in the
superconductor near the surface with the normal metal.Comment: 4 pages, 4 figure
Graphene formed on SiC under various environments: Comparison of Si-face and C-face
The morphology of graphene on SiC {0001} surfaces formed in various
environments including ultra-high vacuum, 1 atm of argon, and 10^-6 to 10^-4
Torr of disilane is studied by atomic force microscopy, low-energy electron
microscopy, and Raman spectroscopy. The graphene is formed by heating the
surface to 1100 - 1600 C, which causes preferential sublimation of the Si
atoms. The argon atmosphere or the background of disilane decreases the
sublimation rate so that a higher graphitization temperature is required, thus
improving the morphology of the films. For the (0001) surface, large areas of
monolayer-thick graphene are formed in this way, with the size of these areas
depending on the miscut of the sample. Results on the (000-1) surface are more
complex. This surface graphitizes at a lower temperature than for the (0001)
surface and consequently the growth is more three-dimensional. In an atmosphere
of argon the morphology becomes even worse, with the surface displaying
markedly inhomogeneous nucleation, an effect attributed to unintentional
oxidation of the surface during graphitization. Use of a disilane environment
for the (000-1) surface is found to produce improved morphology, with
relatively large areas of monolayer-thick graphene.Comment: 22 pages, 11 figures, Proceedings of STEG-2 Conference; eliminated
Figs. 4 and 7 from version 1, for brevity, and added Refs. 18, 29, 30, 31
together with associated discussio
Fossil arbuscular mycorrhizae from the Early Devonian
The 400 million-year-old Rhynie chert has
provided a wealth of information not only of early
land plants, but also of the fungi that inhabited this paleoecosystem. In this paper we report the first unequivocal evidence of arbuscules in an endomycorrhizal
symbiosis. A new genus, Glomites, is characterized
by extraradical, aseptate hyphae with a two-parted
wall, and an intraradical, highly branched network of
thin-walled hyphae. Hyphal branches produce terminal,
elongate-globose multilayered spores that lack a
basal septum. Other hyphae penetrate cell walls and
form arbuscules. Arbuscules are morphologically
identical to those of living arbuscular mycorrhizae (AM)
in consisting of a basal trunk and highly dichotomous
distal branches that form a bush-like tuft. Arbuscules
are confined to a narrow band of specialized thinwalled
cells in the outer cortex that continue to be
meristematic. Features of the fossil biotroph are compared
with those of extant arbuscular mycorrhizae.
Although interpretations regarding the evolution of
mycorrhizal mutualisms continue to be speculative,
the demonstration of arbuscules in the Early Devonian
indicates that nutrient transfer is an ancient phenomenon
that may have been in existence when plants
invaded the land
Disorder-induced phonon self-energy of semiconductors with binary isotopic composition
Self-energy effects of Raman phonons in isotopically disordered
semiconductors are deduced by perturbation theory and compared to experimental
data. In contrast to the acoustic frequency region, higher-order terms
contribute significantly to the self-energy at optical phonon frequencies. The
asymmetric dependence of the self-energy of a binary isotope system on the concentration of the heavier isotope mass x can be explained by
taking into account second- and third-order perturbation terms. For elemental
semiconductors, the maximum of the self-energy occurs at concentrations with
, depending on the strength of the third-order term. Reasonable
approximations are imposed that allow us to derive explicit expressions for the
ratio of successive perturbation terms of the real and the imaginary part of
the self-energy. This basic theoretical approach is compatible with Raman
spectroscopic results on diamond and silicon, with calculations based on the
coherent potential approximation, and with theoretical results obtained using
{\it ab initio} electronic theory. The extension of the formalism to binary
compounds, by taking into account the eigenvectors at the individual
sublattices, is straightforward. In this manner, we interpret recent
experimental results on the disorder-induced broadening of the TO (folded)
modes of SiC with a -enriched carbon sublattice.
\cite{Rohmfeld00,Rohmfeld01}Comment: 29 pages, 9 figures, 2 tables, submitted to PR
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