47 research outputs found
Transport of The Fluorescent Substrate ASP+ by Organic Cation Transporter-3 in Human Corneal Epithelial Cells
ABSTRACT
Organic cation transporter-3 (OCT3) is expressed abundantly throughout the body, but little is known about the presence of these transporters within the eye and, more specifically, the cornea epithelium. An extensive library of compounds interacts with OCT3, including the fluorescent molecule ASP+ and metformin. Metformin is an OCT3 substrate and antidiabetic medication that can lower the risk of eye-related diseases like keratopathy and retinopathy linked to hyperglycemia. Utilizing high throughput microplate assays in a human cornea epithelial cell line (HCE-S), the time-dependent saturation of ASP+ uptake and the competition of ASP+ uptake by corticosterone (CORT), a known selective inhibitor of OCT3 was evaluated. The hypothesis is that OCT3 is present and functional in human corneal epithelial HCE-S cells. The specific aims are to determine the functionality of OCT3 using saturation and competition assays that provide uptake capacity, transporter kinetics, and potency information. Saturation (Bmax and Kd) and competition (IC50) data help to establish the expression and function of OCT3 in HCE-S cells as a model to understand better the transporter’s function in the human cornea epithelial cells. The findings suggest OCT3 is robustly expressed in HCE-S cells and can function to transport ASP+. At baseline (25 mM glucose levels), the HCE-S cell line expresses transporters like OCT3 (and likely other isoforms) that can bind and transport the fluorescent substrate ASP+, which can be blocked by CORT and decynium22 (D22). The ASP+ saturation assay and time trial 30-minute uptake experiments are better for uptake capacity and affinity (Bmax ≅ 1100 RFU; Kd ≅ 272 µM). CORT competition assay using higher glucose levels may potentially decrease the potency of CORT to inhibit ASP+ uptake in HCE-S cells (IC50 ≅ 283 µM (baseline); ≅1717 µM (50 mM glucose, 24 hrs.). Our results also imply that other non-OCT3 transporters are present in this endogenous cell model capable of ASP+ uptake, as evidenced by our non-specific binding measurements using a non-selective inhibitor, D22. The next stage of competition experiments will use metformin to confirm that OCT3 is active in the HCE-S cell line. This work has future implications for establishing corneal cells as a new model to study OCT3 activity, test the pharmacological characteristics of ligands, and develop alternate administration routes for metformin (e.g., as eye drops)
Patient and healthcare professional perspectives on implementing patient-reported outcome measures in gender-affirming care: a qualitative study
Objectives: Patient and healthcare professional perspectives are needed to develop a gender-affirming care patient-reported outcome measure (PROM) implementation plan. We aimed to identify top considerations relevant to gender-affirming care PROM implementation from patient and healthcare professional perspectives.
Design, settings and participants: This qualitative study conducted in the UK between January and April 2023 includes focus groups with a patient sample diverse in age and gender identity, and a healthcare professional sample diverse in age and role. Established methods in implementation science and the Consolidated Framework for Implementation Research were used to create interview guides, and analyse data. Focus groups were audio recorded, transcribed verbatim and analysed by two independent researchers. Patient and healthcare professional focus groups were conducted separately.
Primary outcome measures: Patient and healthcare professional perspectives on PROM implementation were explored through focus groups and until data saturation.
Results: A total of 7 virtual focus groups were conducted with 24 participants (14 patients, mean (SD) age, 43 (14.5); 10 healthcare professionals, mean (SD) age, 46 (11.3)). From patient perspectives, key barriers to PROM implementation were mistrust with PROMs, lack of accessibility, burden, and lack of communication on why PROMs are important and how they will help care. From healthcare professional perspectives, key barriers to PROM implementation were lack of accessibility, burden with PROM administration and scoring, costs of implementation (financial and time), and lack of communication on what PROMs are and how they benefit service provision.
Conclusion: Gender-affirming care PROM implementation must address: patient mistrust with PROMs, accessibility, communication on what PROMs are and how they can be used, reducing burden, and hybridised implementation. These factors may also be applicable to other clinical areas interested in implementing PROMs
Trends in postpartum hemorrhage in high resource countries: a review and recommendations from the International Postpartum Hemorrhage Collaborative Group
<p>Abstract</p> <p>Background</p> <p>Postpartum hemorrhage (PPH) is a major cause of maternal mortality and morbidity worldwide. Several recent publications have noted an increasing trend in incidence over time. The international PPH collaboration was convened to explore the observed trends and to set out actions to address the factors identified.</p> <p>Methods</p> <p>We reviewed available data sources on the incidence of PPH over time in Australia, Belgium, Canada, France, the United Kingdom and the USA. Where information was available, the incidence of PPH was stratified by cause.</p> <p>Results</p> <p>We observed an increasing trend in PPH, using heterogeneous definitions, in Australia, Canada, the UK and the USA. The observed increase in PPH in Australia, Canada and the USA was limited solely to immediate/atonic PPH. We noted increasing rates of severe adverse outcomes due to hemorrhage in Australia, Canada, the UK and the USA.</p> <p>Conclusion</p> <p><it>Key Recommendations</it></p> <p indent="1">1. Future revisions of the International Classification of Diseases should include separate codes for atonic PPH and PPH immediately following childbirth that is due to other causes. Also, additional codes are required for placenta accreta/percreta/increta.</p> <p indent="1">2. Definitions of PPH should be unified; further research is required to investigate how definitions are applied in practice to the coding of data.</p> <p indent="1">3. Additional improvement in the collection of data concerning PPH is required, specifically including a measure of severity.</p> <p indent="1">4. Further research is required to determine whether an increased rate of reported PPH is also observed in other countries, and to further investigate potential risk factors including increased duration of labor, obesity and changes in second and third stage management practice.</p> <p indent="1">5. Training should be provided to all staff involved in maternity care concerning assessment of blood loss and the monitoring of women after childbirth. This is key to reducing the severity of PPH and preventing any adverse outcomes.</p> <p indent="1">6. Clinicians should be more vigilant given the possibility that the frequency and severity of PPH has in fact increased. This applies particularly to small hospitals with relatively few deliveries where management protocols may not be defined adequately and drugs or equipment may not be on hand to deal with unexpected severe PPH.</p
Global standards of Constitutional law : epistemology and methodology
Just as it led the philosophy of science to gravitate around scientific practice, the abandonment of all foundationalist aspirations has already begun making political philosophy into an attentive observer of the new ways in which constitutional law is practiced. Yet paradoxically, lawyers and legal scholars are not those who understand this the most clearly. Beyond analyzing the jurisprudence that has emerged from the expansion of constitutional justice, and taking into account the development of international and regional law, the ongoing globalization of constitutional law requires comparing the constitutional laws of individual nations. Following Waldron, the product of this new legal science can be considered as ius gentium. This legal science is not as well established as one might like to think. But it can be developed on the grounds of the practice that consists in ascertaining standards. As abstract types of best “practices” (and especially norms) of constitutional law from around the world, these are only a source of law in a substantive, not a formal, sense. They thus belong to what I should like to call a “second order legal positivity.” In this article I will undertake, both at a methodological and an epistemological level, the development of a model for ascertaining global standards of constitutional law
Readout of a quantum processor with high dynamic range Josephson parametric amplifiers
We demonstrate a high dynamic range Josephson parametric amplifier (JPA) in
which the active nonlinear element is implemented using an array of rf-SQUIDs.
The device is matched to the 50 environment with a Klopfenstein-taper
impedance transformer and achieves a bandwidth of 250-300 MHz, with input
saturation powers up to -95 dBm at 20 dB gain. A 54-qubit Sycamore processor
was used to benchmark these devices, providing a calibration for readout power,
an estimate of amplifier added noise, and a platform for comparison against
standard impedance matched parametric amplifiers with a single dc-SQUID. We
find that the high power rf-SQUID array design has no adverse effect on system
noise, readout fidelity, or qubit dephasing, and we estimate an upper bound on
amplifier added noise at 1.6 times the quantum limit. Lastly, amplifiers with
this design show no degradation in readout fidelity due to gain compression,
which can occur in multi-tone multiplexed readout with traditional JPAs.Comment: 9 pages, 8 figure
Measurement-Induced State Transitions in a Superconducting Qubit: Within the Rotating Wave Approximation
Superconducting qubits typically use a dispersive readout scheme, where a
resonator is coupled to a qubit such that its frequency is qubit-state
dependent. Measurement is performed by driving the resonator, where the
transmitted resonator field yields information about the resonator frequency
and thus the qubit state. Ideally, we could use arbitrarily strong resonator
drives to achieve a target signal-to-noise ratio in the shortest possible time.
However, experiments have shown that when the average resonator photon number
exceeds a certain threshold, the qubit is excited out of its computational
subspace, which we refer to as a measurement-induced state transition. These
transitions degrade readout fidelity, and constitute leakage which precludes
further operation of the qubit in, for example, error correction. Here we study
these transitions using a transmon qubit by experimentally measuring their
dependence on qubit frequency, average photon number, and qubit state, in the
regime where the resonator frequency is lower than the qubit frequency. We
observe signatures of resonant transitions between levels in the coupled
qubit-resonator system that exhibit noisy behavior when measured repeatedly in
time. We provide a semi-classical model of these transitions based on the
rotating wave approximation and use it to predict the onset of state
transitions in our experiments. Our results suggest the transmon is excited to
levels near the top of its cosine potential following a state transition, where
the charge dispersion of higher transmon levels explains the observed noisy
behavior of state transitions. Moreover, occupation in these higher energy
levels poses a major challenge for fast qubit reset
Overcoming leakage in scalable quantum error correction
Leakage of quantum information out of computational states into higher energy
states represents a major challenge in the pursuit of quantum error correction
(QEC). In a QEC circuit, leakage builds over time and spreads through
multi-qubit interactions. This leads to correlated errors that degrade the
exponential suppression of logical error with scale, challenging the
feasibility of QEC as a path towards fault-tolerant quantum computation. Here,
we demonstrate the execution of a distance-3 surface code and distance-21
bit-flip code on a Sycamore quantum processor where leakage is removed from all
qubits in each cycle. This shortens the lifetime of leakage and curtails its
ability to spread and induce correlated errors. We report a ten-fold reduction
in steady-state leakage population on the data qubits encoding the logical
state and an average leakage population of less than
throughout the entire device. The leakage removal process itself efficiently
returns leakage population back to the computational basis, and adding it to a
code circuit prevents leakage from inducing correlated error across cycles,
restoring a fundamental assumption of QEC. With this demonstration that leakage
can be contained, we resolve a key challenge for practical QEC at scale.Comment: Main text: 7 pages, 5 figure
Dynamics of magnetization at infinite temperature in a Heisenberg spin chain
Understanding universal aspects of quantum dynamics is an unresolved problem
in statistical mechanics. In particular, the spin dynamics of the 1D Heisenberg
model were conjectured to belong to the Kardar-Parisi-Zhang (KPZ) universality
class based on the scaling of the infinite-temperature spin-spin correlation
function. In a chain of 46 superconducting qubits, we study the probability
distribution, , of the magnetization transferred across the
chain's center. The first two moments of show superdiffusive
behavior, a hallmark of KPZ universality. However, the third and fourth moments
rule out the KPZ conjecture and allow for evaluating other theories. Our
results highlight the importance of studying higher moments in determining
dynamic universality classes and provide key insights into universal behavior
in quantum systems
Suppressing quantum errors by scaling a surface code logical qubit
Practical quantum computing will require error rates that are well below what
is achievable with physical qubits. Quantum error correction offers a path to
algorithmically-relevant error rates by encoding logical qubits within many
physical qubits, where increasing the number of physical qubits enhances
protection against physical errors. However, introducing more qubits also
increases the number of error sources, so the density of errors must be
sufficiently low in order for logical performance to improve with increasing
code size. Here, we report the measurement of logical qubit performance scaling
across multiple code sizes, and demonstrate that our system of superconducting
qubits has sufficient performance to overcome the additional errors from
increasing qubit number. We find our distance-5 surface code logical qubit
modestly outperforms an ensemble of distance-3 logical qubits on average, both
in terms of logical error probability over 25 cycles and logical error per
cycle ( compared to ). To investigate
damaging, low-probability error sources, we run a distance-25 repetition code
and observe a logical error per round floor set by a single
high-energy event ( when excluding this event). We are able
to accurately model our experiment, and from this model we can extract error
budgets that highlight the biggest challenges for future systems. These results
mark the first experimental demonstration where quantum error correction begins
to improve performance with increasing qubit number, illuminating the path to
reaching the logical error rates required for computation.Comment: Main text: 6 pages, 4 figures. v2: Update author list, references,
Fig. S12, Table I
Measurement-induced entanglement and teleportation on a noisy quantum processor
Measurement has a special role in quantum theory: by collapsing the
wavefunction it can enable phenomena such as teleportation and thereby alter
the "arrow of time" that constrains unitary evolution. When integrated in
many-body dynamics, measurements can lead to emergent patterns of quantum
information in space-time that go beyond established paradigms for
characterizing phases, either in or out of equilibrium. On present-day NISQ
processors, the experimental realization of this physics is challenging due to
noise, hardware limitations, and the stochastic nature of quantum measurement.
Here we address each of these experimental challenges and investigate
measurement-induced quantum information phases on up to 70 superconducting
qubits. By leveraging the interchangeability of space and time, we use a
duality mapping, to avoid mid-circuit measurement and access different
manifestations of the underlying phases -- from entanglement scaling to
measurement-induced teleportation -- in a unified way. We obtain finite-size
signatures of a phase transition with a decoding protocol that correlates the
experimental measurement record with classical simulation data. The phases
display sharply different sensitivity to noise, which we exploit to turn an
inherent hardware limitation into a useful diagnostic. Our work demonstrates an
approach to realize measurement-induced physics at scales that are at the
limits of current NISQ processors