The quantized Hall conductance of a single atomic wire: A proposal based on synthetic dimensions

We propose a method by which the quantization of the Hall conductance can be directly measured in the transport of a one-dimensional atomic gas. Our approach builds on two main ingredients: (1) a constriction optical potential, which generates a mesoscopic channel connected to two reservoirs, and (2) a time-periodic modulation of the channel, specifically designed to generate motion along an additional synthetic dimension. This fictitious dimension is spanned by the harmonic-oscillator modes associated with the tightly-confined channel, and hence, the corresponding "lattice sites" are intimately related to the energy of the system. We analyze the quantum transport properties of this hybrid two-dimensional system, highlighting the appealing features offered by the synthetic dimension. In particular, we demonstrate how the energetic nature of the synthetic dimension, combined with the quasi-energy spectrum of the periodically-driven channel, allows for the direct and unambiguous observation of the quantized Hall effect in a two-reservoir geometry. Our work illustrates how topological properties of matter can be accessed in a minimal one-dimensional setup, with direct and practical experimental consequences.

Variations in Arterial Blood Pressure after Kidney Transplantation

The course of hypertension within the first 2 months after kidney transplantation was correlated with renal function, plasma renin activity (PRA), and the daily maintenance dose of prednisone in 18 homograft recipients. During acute rejection blood pressure (BP) closely correlated with PRA. Patients with normal homograft function showed an increase in BP early after transplantation which in most returned to normal 3-8 weeks later. In the latter group no correlation could be found between the level of BP and PRA, however the BP correlated closely with the dose of prednisone. These observations suggest that during acute rejection the increase in BP may at least partly be mediated by a renal pressor mechanism, whereas with normal renal function the high dose of glucocorticoids may play an important role in the development of hypertension.</jats:p

Recovery from Hepatorenal Syndrome after Orthotopic Liver Transplantation

Three patients with progressive renal failure and advanced hepatic insufficiency due to cirrhosis of the liver underwent orthotopic liver transplantation. All three patients had immediate improvement in hepatic function and within two weeks after liver replacement regained nearly normal kidney function. However, the renal recovery was delayed in each case, and its course was not uniform. Plasma renin activity was high, and renin substrate was low before transplantation in one case in which these measurements were obtained; both returned to normal soon after liver replacement. (N Engl J Med 289:1155–1159, 1973). © 1973, Massachusetts Medical Society. All rights reserved

Susceptibility of optimal train schedules to stochastic disturbances of process times

This work focuses on the stochastic evaluation of train schedules computed by a microscopic scheduler of railway operations based on deterministic information. The research question is to assess the degree of sensitivity of various rescheduling algorithms to variations in process times (running and dwell times). In fact, the objective of railway traffic management is to reduce delay propagation and to increase disturbance robustness of train schedules at a network scale. We present a quantitative study of traffic disturbances and their effects on the schedules computed by simple and advanced rescheduling algorithms. Computational results are based on a complex and densely occupied Dutch railway area; train delays are computed based on accepted statistical distributions, and dwell and running times of trains are subject to additional stochastic variations. From the results obtained on a real case study, an advanced branch and bound algorithm, on average, outperforms a First In First Out scheduling rule both in deterministic and stochastic traffic scenarios. However, the characteristic of the stochastic processes and the way a stochastic instance is handled turn out to have a serious impact on the scheduler performance

Breadth of Vaccinated Cancer Patient Humoral Response to SARS-CoV-2 Spike Protein and RBD Variants

SARS-CoV-2, the virus responsible for the COVID-19 of which several variants have emerged, such as the B.1.351 SARS-CoV-2 variant. The Receptor Binding Domain (RBD), located within the Spike protein is an immunogenic epitope for potent neutralizing antibodies. Current mRNA vaccines encode for the Spike protein, allowing the body to build antigen-specific antibodies. Assays measuring protective antibodies are essential to manage the COVID-19 pandemic and can be used as a platform for variant screening. RBD-foldon 2.2 is a novel antigen produced by fusing RBD with the trimerization domain Fibritin from Bacteriophage T4. Its amino acid sequence is based on the original Wuhan strain. (Breckenridge, 2021). B.1.351 RBD-foldon 2.2 antigen is identical to RBD-foldon 2.2, except it uses the B.1.351 variant RBD sequence. Using cancer patient sera samples, the breadth and robustness of response was examined in comparison to patients that indicated “no chronic conditions”. We hypothesized there would be a difference in humoral response to RBD-variant antigens in COVID-19 vaccinated cancer patients undergoing treatment vs patients with no chronic conditions. For sample selection, cancer patients were age/sex matched to individuals with no underlying health conditions, that received the same mRNA vaccine within 2 weeks of each other. To quantify antibody levels, ELISA end-point titers were performed. ELISAs detected levels of IgG and IgA antibodies against Spike, RBD-foldon, RBD-foldon 2.2, and RBD-foldon B.1.351. (Bushau, 2021). The statistical analysis used was a two-tailed student’s t-test to compare mean value of end-point titers between experimental and control groups. No significant difference between experimental and control groups for any antibody-antigen combination. B.1.351 RBD-foldon appears to elicit a lower response than RBD-foldon 2.2. Lower response may be explained by the mRNA sequence used in current vaccines encodes for original Wuhan SARS-CoV-2 spike protein. The platform is predictive of the level of antibody protection for variant screening

Spin transport in a one-dimensional quantum wire

We analyze the spin transport through a finite-size one-dimensional interacting wire connected to noninteracting leads. By combining renormalization-group arguments with other analytic considerations such as the memory function technique and instanton tunneling, we find the temperature dependence of the spin conductance in different parameter regimes in terms of interactions and the wire length. The temperature dependence is found to be nonmonotonic. In particular, the system approaches perfect spin conductance at zero temperature for both attractive and repulsive interactions, in contrast with the static spin conductivity. We discuss the connection of our results to recent experiments with ultracold atoms and compare the theoretical prediction to experimental data in the parameter regime where temperature is the largest energy scale.Comment: 16 pages, 10 figure

The structure and function of complex networks

Inspired by empirical studies of networked systems such as the Internet, social networks, and biological networks, researchers have in recent years developed a variety of techniques and models to help us understand or predict the behavior of these systems. Here we review developments in this field, including such concepts as the small-world effect, degree distributions, clustering, network correlations, random graph models, models of network growth and preferential attachment, and dynamical processes taking place on networks.Comment: Review article, 58 pages, 16 figures, 3 tables, 429 references, published in SIAM Review (2003

Simulations of Aerodynamic Damping for MEMS Resonators

Aerodynamic damping for MEMS resonators is studied based on the numerical solution of Boltzmann-ESBGK equation. A compact model is then developed based on numerical simulations for a wide range of Knudsen numbers. The damping predictions are compared with both Reynold equation based models and several sets of experimental data. It has been found that the structural damping is dominant at low pressures (high Knudsen numbers). For cases with small length-to-width ratios and large vibration amplitudes, the threedimensionality effects must be taken into account. Finally, an uncertainty quantification approach based on the probability transformation method has been applied to assess the influence of pressure and geometric uncertainties. The output probability density functions (PDF) of the damping ratio has been studied for various input PDF of beam geometry and ambient pressure

Real‐world treatment patterns and outcomes using terlipressin in 203 patients with the hepatorenal syndrome

Background: Hepatorenal syndrome and acute kidney injury are common complications of decompensated cirrhosis, and terlipressin is recommended as first‐line vasoconstrictor therapy. However, data on its use outside of clinical trials are lacking. / Aims: To assess practice patterns and outcomes around vasoconstrictor use for hepatorenal syndrome in UK hospitals. / Methods: This was a multicentre chart review study. Data were extracted from medical records of patients diagnosed with hepatorenal syndrome and treated by vasoconstrictor drugs between January 2013 and December 2017 at 26 hospitals in the United Kingdom. The primary outcome was improvement of kidney function, defined as complete response (serum creatinine improved to ≤1.5 mg/dL), partial response (serum creatinine reduction of ≥20% but >1.5 mg/dL) and overall response (complete or partial response). Other outcomes included need for dialysis, mortality, liver transplantation and adverse events. / Results: Of the 225 patients included in the analysis, 203 (90%) were treated with terlipressin (median duration, 6 days; range: 2‐24 days). Mean (±standard deviation) serum creatinine at vasopressor initiation was 3.25 ± 1.64 mg/dL. Terlipressin overall response rate was 73%. Overall response was higher in patients with mild acute kidney injury (baseline serum creatinine <2.25 mg/dL), compared to those with moderate (serum creatinine ≥2.25 mg/dL and <3.5 mg/dL) or severe (serum creatinine ≥3.5 mg/dL). Ninety‐day survival was 86% for all patients (93% for overall responders vs 66% for treatment nonresponders, P < 0.0001). / Conclusion: Terlipressin is the most commonly prescribed vasoconstrictor for patients with hepatorenal syndrome in the United Kingdom. Treatment with terlipressin in patients with less severe acute kidney injury (serum creatinine <2.25 mg/dL) was associated with higher treatment responses, and 90‐day survival