10,051 research outputs found
Inferring DNA sequences from mechanical unzipping: an ideal-case study
We introduce and test a method to predict the sequence of DNA molecules from
in silico unzipping experiments. The method is based on Bayesian inference and
on the Viterbi decoding algorithm. The probability of misprediction decreases
exponentially with the number of unzippings, with a decay rate depending on the
applied force and the sequence content.Comment: Source as TeX file with ps figure
IELTS and an English for academic study programme: points of similarity and areas of divergence
This paper describes an analysis of assessments on a preparatory, English for academic study (EAS) programme at a New Zealand university and of IELTS tests. The university accepts students with the required Band 6 overall in IELTS, and also those who graduate from the EAS programme with Grade B and above for its undergraduate programmes. Other institutions also accept this EAS certificate as evidence of English language proficiency. However, as far as we are aware there has been no formal comparative study of the points of similarities and areas of divergence between IELTS and such programmes. The identification of similarities and differences allows for a detailed profile of the knowledge, skills, and competencies acquired by students who successfully complete such pre-sessional programmes, as compared with students who have completed an IELTS preparation programme. It is anticipated that the information provided, will be of benefit to academic English and literacy practitioners
One-Liners
One-Liners from P.T. Borgia, J. Irelan and E.U. Selker, and B.C. Turner and A. Fairfiel
3D-Printed Hollow Microneedle-Lateral Flow Devices for Rapid Blood-Free Detection of C-Reactive Protein and Procalcitonin
\ua9 2023 The Authors. Advanced Materials Technologies published by Wiley-VCH GmbH.Hollow microneedle devices as a technology for interstitial fluid extraction show promise for the minimally invasive point-of-care detection of analytes. Despite increasing efforts toward on-patch diagnostics, the use of hollow microneedles has been limited due to the complexity caused by integrating hollow microneedles with established point-of-care diagnostic techniques. Herein, a 3D printing method is utilized, to provide low-cost manufacturing of custom-designed hollow microneedle devices, allowing for easy integration with lateral flow assays for rapid and blood-free diagnostics. Microneedle surface modification through PEGylation results in prolonged and enhanced hydrophilicity, enabling passive uptake of small volume samples (≈22.5 \ub5L) and an enhanced shelf life. The hollow microneedle devices are deemed non-cytotoxic to cell types found within the skin following short-term and prolonged exposure in accordance with ISO10993. Furthermore, the devices demonstrate high mechanical strength and successfully penetrate porcine skin grafts without damaging the surrounding skin morphology. This work also demonstrates for the first time the use of hollow microneedles for the simultaneous detection, at clinically relevant concentrations, of C-reactive protein (LoD = 10 \ub5g mL−1) and procalcitonin (LoD = 1 ng mL−1), through porcine skin, ultimately demonstrating the beneficial use of manufactured 3D-printed hollow microneedles towards low-cost blood-free diagnostics of inflammation markers
Conductive Polymer-Coated 3D Printed Microneedles: Biocompatible Platforms for Minimally Invasive Biosensing Interfaces
\ua9 2023 The Authors. Small published by Wiley-VCH GmbH.Conductive polymeric microneedle (MN) arrays as biointerface materials show promise for the minimally invasive monitoring of analytes in biodevices and wearables. There is increasing interest in microneedles as electrodes for biosensing, but efforts have been limited to metallic substrates, which lack biological stability and are associated with high manufacturing costs and laborious fabrication methods, which create translational barriers. In this work, additive manufacturing, which provides the user with design flexibility and upscale manufacturing, is employed to fabricate acrylic-based microneedle devices. These microneedle devices are used as platforms to produce intrinsically-conductive, polymer-based surfaces based on polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS). These entirely polymer-based solid microneedle arrays act as dry conductive electrodes while omitting the requirement of a metallic seed layer. Two distinct coating methods of 3D-printed solid microneedles, in situ polymerization and drop casting, enable conductive functionality. The microneedle arrays penetrate ex vivo porcine skin grafts without compromising conductivity or microneedle morphology and demonstrate coating durability over multiple penetration cycles. The non-cytotoxic nature of the conductive microneedles is evaluated using human fibroblast cells. The proposed fabrication strategy offers a compelling approach to manufacturing polymer-based conductive microneedle surfaces that can be further exploited as platforms for biosensing
Theory of finite-entanglement scaling at one-dimensional quantum critical points
Studies of entanglement in many-particle systems suggest that most quantum
critical ground states have infinitely more entanglement than non-critical
states. Standard algorithms for one-dimensional many-particle systems construct
model states with limited entanglement, which are a worse approximation to
quantum critical states than to others. We give a quantitative theory of
previously observed scaling behavior resulting from finite entanglement at
quantum criticality: the scaling theory of finite entanglement is only
superficially similar to finite-size scaling, and has a different physical
origin. We find that finite-entanglement scaling is governed not by the scaling
dimension of an operator but by the "central charge" of the critical point,
which counts its universal degrees of freedom. An important ingredient is the
recently obtained universal distribution of density-matrix eigenvalues at a
critical point\cite{calabrese1}. The parameter-free theory is checked against
numerical scaling at several quantum critical points.Comment: 4 pages + 2 pages supplementary informatio
The Tensor to Scalar Ratio of Phantom Dark Energy Models
We investigate the anisotropies in the cosmic microwave background in a class
of models which possess a positive cosmic energy density but negative pressure,
with a constant equation of state w = p/rho < -1. We calculate the temperature
and polarization anisotropy spectra for both scalar and tensor perturbations by
modifying the publicly available code CMBfast. For a constant initial curvature
perturbation or tensor normalization, we have calculated the final anisotropy
spectra as a function of the dark energy density and equation of state w and of
the scalar and tensor spectral indices. This allows us to calculate the
dependence of the tensor-to-scalar ratio on w in a model with phantom dark
energy, which may be important for interpreting any future detection of
long-wavelength gravitational waves.Comment: 5 pages, 4 figure
The Cosmological Constant is Back
A diverse set of observations now compellingly suggest that Universe
possesses a nonzero cosmological constant. In the context of quantum-field
theory a cosmological constant corresponds to the energy density of the vacuum,
and the wanted value for the cosmological constant corresponds to a very tiny
vacuum energy density. We discuss future observational tests for a cosmological
constant as well as the fundamental theoretical challenges---and
opportunities---that this poses for particle physics and for extending our
understanding of the evolution of the Universe back to the earliest moments.Comment: latex, 8 pages plus one ps figure available as separate compressed
uuencoded fil
A limit on the detectability of the energy scale of inflation
We show that the polarization of the cosmic microwave background can be used
to detect gravity waves from inflation if the energy scale of inflation is
above 3.2 times 10^15 GeV. These gravity waves generate polarization patterns
with a curl, whereas (to first order in perturbation theory) density
perturbations do not. The limiting ``noise'' arises from the second--order
generation of curl from density perturbations, or rather residuals from its
subtraction. We calculate optimal sky coverage and detectability limits as a
function of detector sensitivity and observing time.Comment: 4 pages, 3 figures, submitted to PR
SU(1,1) symmetry of multimode squeezed states
We show that a class of multimode optical transformations that employ linear
optics plus two-mode squeezing can be expressed as SU(1,1) operators. These
operations are relevant to state-of-the-art continuous variable quantum
information experiments including quantum state sharing, quantum teleportation,
and multipartite entangled states. Using this SU(1,1) description of these
transformations, we obtain a new basis for such transformations that lies in a
useful representation of this group and lies outside the often-used restriction
to Gaussian states. We analyze this basis, show its application to a class of
transformations, and discuss its extension to more general quantum optical
networks
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