Precision Measurement of Trident Production in Strong Electromagnetic Fields

We demonstrate experimentally that the trident process $e^-\rightarrow e^-e^+e^-$ in a strong external field, with a spatial extension comparable to the effective radiation length, is well understood theoretically. The experiment, conducted at CERN, probes values for the strong field parameter $\chi$ up to 2.4. Experimental data and theoretical expectations using the Local Constant Field Approximation show remarkable agreement over almost 3 orders of magnitude in yield.Comment: 4 pages, 2 figure

Online wave estimation using vessel motion measurements

In this paper, a computationally efficient online sea state estimation algorithm is proposed for estimation of the onsite sea state. The algorithm finds the wave spectrum estimate from motion measurements in heave, roll and pitch by iteratively solving a set of linear equations. The main vessel parameters and motion transfer functions are required as input. Apart from this the method is signal-based, with no assumptions on the wave spectrum shape, and as a result it is computationally efficient. The algorithm is implemented in a dynamic positioning (DP) control system, and tested through simulations in different sea states, with heading changes. Discrete stability analysis is performed to find iteration gains in the algorithm

Correlation Measurement of Squeezed Light

We study the implementation of a correlation measurement technique for the characterization of squeezed light which is nearly free of electronic noise. With two different sources of squeezed light, we show that the sign of the covariance coefficient, revealed from the time resolved correlation data, is witnessing the presence of squeezing in the system. Furthermore, we estimate the degree of squeezing using the correlation method and compare it to the standard homodyne measurement scheme. We show that the role of electronic detector noise is minimized using the correlation approach as opposed to homodyning where it often becomes a crucial issue

Differential Measurement of Trident Production in Strong Electromagnetic Fields

In this paper, we present experimental results and numerical simulations of trident production, $e^-\rightarrow e^-e^+e^-$, in a strong electromagnetic field. The experiment was conducted at CERN for the purpose of probing the strong-field parameter $\chi$ up to 2.4, using a 200 GeV electron beam penetrating a 400 $\mu$m thick germanium crystal oriented along the $\langle 110\rangle$ axis. For the current experimental parameters we found that the trident process is primarily a two-step process, and show remarkable agreement between theoretical predictions and experimental data. This paper is an extension of the previously published paper (Phys. Rev. Lett. 130, 071601 (2023)) and features new analysis differential in the energy of the produced positron and electron in the trident process. Even for the more demanding differential analysis, we find good agreement between theoretical predictions and experimental data, while a slight discrepancy is found in the high energy tail of the trident spectrum. This discrepancy could be an indication of the direct process, but further investigation is needed due to the large uncertainties in this part of the spectrum. Finally we present a suggestion for a future experiment, aiming to probe the direct process using thin crystals

Breathing Exercises for Patients with Asthma in Specialist Care:A Multicenter Randomized Clinical Trial

RATIONALE: Moderate to severe asthma is associated with impaired asthma control and quality of life (QoL) despite access to specialist care and modern pharmacotherapy. Breathing exercises (BrEX) improve QoL in incompletely controlled mild asthma, but impact in moderate to severe asthma is unknown. OBJECTIVES: To investigate the effectiveness of BrEX as adjuvant treatment on QoL in patients with uncontrolled moderate to severe asthma. METHODS: Adult patients with incompletely controlled asthma attending respiratory specialist clinics were randomized to usual specialist care (UC) or UC and BrEX (UC + BrEX) with three individual physiotherapist-delivered sessions and home exercises. Primary outcome was asthma-related QoL (Mini-Asthma Quality of Life Questionnaire [Mini-AQLQ]) at 6 months on the basis of intention-to-treat analysis. Secondary outcomes: Mini-AQLQ at 12 months, lung function, 6-minute-walk test, physical activity level, Nijmegen Questionnaire, Hospital Anxiety and Depression Scale, and adverse events. Repeated-measures mixed-effects models were used to analyze data. Poisson regression models were used to analyze adverse event incidence rate ratio. RESULTS: A total of 193 participants were allocated to UC + BrEX (n = 94) or UC (n = 99). UC + BrEX was superior in the primary outcome (adjusted mean change difference, 0.35; 95% confidence interval [CI], 0.07 to 0.62). Superiority in Mini-AQLQ was sustained at 12 months (0.38; 95% CI, 0.12 to 0.65). A minor improvement in Hospital Anxiety and Depression Scale depression score at 6 months favoring UC + BrEX (−0.90; 95% CI, −1.67 to −0.14) was observed. Asthma-related adverse events occurred similarly in UC + BrEX and UC participants: 14.9% versus 18.1% (P = 0.38). CONCLUSIONS: BrEX as add-on to usual care improve asthma-related QoL in incompletely controlled asthma regardless of severity and with no evidence of harm. Clinical trial registered with www.clinicaltrials.gov (NCT 03127059)