Implementation of Time-Delay Interferometry for LISA

We discuss the baseline optical configuration for the Laser Interferometer Space Antenna (LISA) mission, in which the lasers are not free-running, but rather one of them is used as the main frequency reference generator (the {\it master}) and the remaining five as {\it slaves}, these being phase-locked to the master (the {\it master-slave configuration}). Under the condition that the frequency fluctuations due to the optical transponders can be made negligible with respect to the secondary LISA noise sources (mainly proof-mass and shot noises), we show that the entire space of interferometric combinations LISA can generate when operated with six independent lasers (the {\it one-way method}) can also be constructed with the {\it master-slave} system design. The corresponding hardware trade-off analysis for these two optical designs is presented, which indicates that the two sets of systems needed for implementing the {\it one-way method}, and the {\it master-slave configuration}, are essentially identical. Either operational mode could therefore be implemented without major implications on the hardware configuration. We then.......Comment: 39 pages, 6 figures, 2 table

Teaching in the COVID-19 era: Understanding the opportunities and barriers for teacher agency

The school closures necessitated by the COVID-19 pandemic created a rapid shift to alternative modes of educational delivery, primarily online learning and teacher-supported home-schooling. This shift has revealed deep inequities in education systems worldwide, as many children lost access to teachers and schooling. An effective response to these changes has tested teachers’ personal capacities and individual and collective agency intensely. The research lab we report on within this paper aimed to develop a better understanding of teacher agency in meeting the challenges of the pandemic and the physical and relational enablers and constraints of their environment. Drawing on case study reports from six international contexts and a series of online discussions with research lab participants, this study explores teachers’ enactment of agency in the context of various circumstances and environments. The authors argue that it is imperative that education systems support the enhancement of teachers’ personal and collective agency in the face of continued disruption to schooling and ongoing challenges to educational equity

On a diffuse interface model for tumour growth with non-local interactions and degenerate mobilities

We study a non-local variant of a diffuse interface model proposed by Hawkins--Darrud et al. (2012) for tumour growth in the presence of a chemical species acting as nutrient. The system consists of a Cahn--Hilliard equation coupled to a reaction-diffusion equation. For non-degenerate mobilities and smooth potentials, we derive well-posedness results, which are the non-local analogue of those obtained in Frigeri et al. (European J. Appl. Math. 2015). Furthermore, we establish existence of weak solutions for the case of degenerate mobilities and singular potentials, which serves to confine the order parameter to its physically relevant interval. Due to the non-local nature of the equations, under additional assumptions continuous dependence on initial data can also be shown.Comment: 28 page

Long-Term Results After the Glycoprotein IIb/IIIa Inhibitor Abciximab in Unstable Angina

BACKGROUND: This study was designed to investigate long-term effects of the glycoprotein IIb/IIIa inhibitor abciximab in patients with acute coronary syndrome without ST elevation who were not scheduled for coronary intervention. METHODS AND RESULTS: A total of 7800 patients were included with an acute coronary syndrome without ST elevation, documented by either elevated cardiac troponin or transient or persistent ST-segment depression. They were randomized to abciximab bolus and 24-hour infusion, abciximab bolus and 48-hour infusion, or matching placebo. The overall 1-year mortality rate was 8.3% (649 patients). One-year mortality was 7.8% in the placebo group and 8.2% in the 24-hour and 9.0% in the 48-hour abciximab infusion group. Compared with placebo, the hazard ratio for the 24-hour infusion of abciximab was 1.1 (95% CI 0.86 to 1.29), and for the 48-hour infusion, it was 1.2 (95% CI 0.95 to 1.41). The lack of benefit of abciximab was observed in every subgroup studied. Patients with negative troponin or elevated C-reactive protein had a higher mortality rate after treatment with abciximab for 48 hours than with placebo: 8.5% versus 5.8% in those with negative troponin (P=0.02), 16.3% versus 12.1% in those with elevated C-reactive protein (P=0.04). CONCLUSIONS: Compared with placebo, abciximab did not provide any survival benefit at 1 year in patients admitted with an acute coronary syndrome with ST depression and/or elevated troponin who were not scheduled to undergo early coronary revascularization. In subgroups of patients, in particular those with low cardiac troponin or elevated C-reactive protein, abciximab was associated with excess mortality

Transcript of The Dory Derby Accident

This story is an excerpt from a longer interview that was collected as part of the Launching through the Surf: The Dory Fleet of Pacific City project. In this story, Don Grotjohn recounts an accident that occurred during a Dory Derby competition

Classification of a supersolid: Trial wavefunctions, Symmetry breakings and Excitation spectra

A state of matter is characterized by its symmetry breaking and elementary excitations. A supersolid is a state which breaks both translational symmetry and internal $U(1)$ symmetry. Here, we review some past and recent works in phenomenological Ginsburg-Landau theories, ground state trial wavefunctions and microscopic numerical calculations. We also write down a new effective supersolid Hamiltonian on a lattice. The eigenstates of the Hamiltonian contains both the ground state wavefunction and all the excited states (supersolidon) wavefunctions. We contrast various kinds of supersolids in both continuous systems and on lattices, both condensed matter and cold atom systems. We provide additional new insights in studying their order parameters, symmetry breaking patterns, the excitation spectra and detection methods.Comment: REVTEX4, 19 pages, 3 figure

Sustained ventricular arrhythmias among patients with acute coronary syndromes with no ST-segment elevation: incidence, predictors, and outcomes

BACKGROUND: The prognosis of ventricular arrhythmias among patients with non-ST-elevation acute coronary syndromes is unknown. We studied the incidence, predictors, and outcomes of sustained ventricular arrhythmias in 4 large randomized trials of such patients. METHODS AND RESULTS: We pooled the datasets of the Global Use of Streptokinase and tPA for Occluded Arteries (GUSTO)-IIb, Platelet Glycoprotein IIb/IIIa in Unstable Angina: Receptor Suppression Using Integrilin Therapy (PURSUIT), Platelet IIb/IIIa Antagonism for the Reduction of Acute Coronary Syndrome Events in a Global Organization Network (PARAGON)-A, and PARAGON-B trials (n=26 416). We identified independent predictors of ventricular fibrillation (VF) and ventricular tachycardia (VT) and compared the 30-day and 6-month mortality rates of patients who did (n=552) and did not (n=25 864) develop these arrhythmias during the index hospitalization. Independent predictors of in-hospital VF included prior hypertension, chronic obstructive pulmonary disease, prior myocardial infarction, and ST-segment changes at presentation. Except for hypertension, these variables also independently predicted in-hospital VT. In Cox proportional-hazards modeling, in-hospital VF and VT were independently associated with 30-day mortality (hazard ratio [HR], 23.2 [95% CI, 18.1 to 29.8] for VF and HR, 7.6 [95% CI, 5.5 to 10.4] for VT) and 6-month mortality (HR, 14.8 [95% CI, 12.1 to 18.3] for VF and HR, 5.0 [95% CI, 3.8 to 6.5] for VT). These differences remained significant after excluding patients with heart failure or cardiogenic shock and those who died <24 hours after enrollment. CONCLUSIONS: Despite the use of effective therapies for non-ST-elevation acute coronary syndromes, ventricular arrhythmias in this setting are associated with increased 30-day and 6-month mortality. More effective therapies are needed to improve the survival of patients with these arrhythmias

Cost effectiveness of thrombolytic therapy with tissue plasminogen activator as compared with streptokinase for acute myocardial infarction

BACKGROUND. Patients with acute myocardial infarction who were treated with accelerated tissue plasminogen activator (t-PA) (given over a period of 1 1/2 hours rather than the conventional 3 hours, and with two thirds of the dose given in the first 30 minutes) had a 30-day mortality that was 15 percent lower than that of pati

Active Amplification of the Terrestrial Albedo to Mitigate Climate Change: An Exploratory Study

This study explores the potential to enhance the reflectance of solar insolation by the human settlement and grassland components of the Earth's terrestrial surface as a climate change mitigation measure. Preliminary estimates derived using a static radiative transfer model indicate that such efforts could amplify the planetary albedo enough to offset the current global annual average level of radiative forcing caused by anthropogenic greenhouse gases by as much as 30 percent or 0.76 W/m2. Terrestrial albedo amplification may thus extend, by about 25 years, the time available to advance the development and use of low-emission energy conversion technologies which ultimately remain essential to mitigate long-term climate change. However, additional study is needed to confirm the estimates reported here and to assess the economic and environmental impacts of active land-surface albedo amplification as a climate change mitigation measure.Comment: 21 pages, 3 figures. In press with Mitigation and Adaptation Strategies for Global Change, Springer, N

Association between glycated haemoglobin levels and cardiovascular outcomes in patients with type 2 diabetes and cardiovascular disease: a secondary analysis of the TECOS randomized clinical trial

Aims: Whether glycaemic control is associated with cardiovascular outcomes in patients with type 2 diabetes (T2D) is unclear. Consequently, we assessed the relationship between glycated haemoglobin (HbA1c) and cardiovascular outcomes in a placebo-controlled randomized trial which demonstrated no cardiovascular effect of sitagliptin in patients with T2D and atherosclerotic vascular disease. Methods and results: Secondary analysis of 14 656 TECOS participants with time to event analyses using multivariable Cox proportional hazard models. During a median 3.0 (interquartile range 2.3–3.8) year follow-up, 456 (3.1% of 14 656) patients had first hospitalization for heart failure (HF), 1084 (11.5%) died, 1406 (9.6%) died or were hospitalized for HF, and 1689 (11.5%) had a non-HF cardiovascular event (cardiovascular death, non-fatal stroke, non-fatal myocardial infarction, or hospitalization for unstable angina). Associations between baseline or time-varying HbA1c and cardiovascular outcomes were U-shaped, with the lowest risk when HbA1c was around 7%. Each one-unit increase in the time-varying HbA1c above 7% was associated with an adjusted hazard ratio (HR) of 1.21 [95% confidence interval (CI) 1.11–1.33] for first HF hospitalization, 1.11 (1.03–1.21) for all-cause death, 1.18 (1.09–1.26) for death or HF hospitalization, and 1.10 (1.02–1.17) for non-HF cardiovascular events. Each one-unit decrease in the time-varying HbA1c below 7% was associated with an adjusted HR of 1.35 (95% CI 1.12–1.64) for first HF hospitalization, 1.37 (1.16–1.61) for death, 1.42 (1.23–1.64) for death or HF hospitalization, and 1.22 (1.06–1.41) for non-HF cardiovascular events. Conclusion: Glycated haemogobin exhibits a U-shaped association with cardiovascular outcomes in patients with T2D and atherosclerotic vascular disease, with nadir around 7%. Clinical Trial Registration: ClinicalTrials.gov Identifier: NCT00790205