Field data are needed for a better understanding of sea ice decline in the context of climate change. The rapid technological and methodological advances of the last decade have led to a reconsideration of seismic methods in this matter. In particular, passive seismology has filled an important gap by removing the need to use active sources. We present a seismic experiment where an array of 247 geophones was deployed on sea ice, in the Van Mijen fjord near Sveagruva (Svalbard). The array is a mix of 1C and 3C stations with sampling frequencies of 500 and 1000 Hz. They recorded continuously the ambient seismic field in sea ice between 28 February and 26 March 2019. Data also include active acquisitions on 1 and 26 March with a radar antenna, a shaker unit, impulsive sources, and artificial sources of seismic noise. This data set is of unprecedented quality regarding sea ice seismic monitoring, as it also includes thousands of microseismic events recorded each day. By combining passive seismology approaches with specific array processing methods, we demonstrate that the multimodal dispersion curves of sea ice can be calculated without an active source and then used to infer sea ice properties. We calculated an ice thickness, Young's modulus, and Poisson's ratio with values h = 54 ± 3 cm, E = 3.9 ± 0.15 GPa, and = 0.34 ± 0.02 on 1 March, and h = 58 ± 3 cm, E = 4.4 ± 0.15 GPa, and = 0.32 ± 0.02 on 5 March. These values are consistent with in situ field measurements and observations.
Accurate angular phase data are extracted from angle-resolved scattering measurements made with polarized light using a technique developed in the laboratory. This Ellipsometry of Angle-Resolved Scattering (E.A.R.S.) technique makes it possible to distinguish surface scattering from bulk scattering independent of the scattering levels for different types of samples. Phase data are also investigated in the speckle pattern.
An interferential technique is described to eliminate polarized scattering from optical substrates and coatings. Conditions of annulment are respectively given for surface roughness and for bulk heterogeneity, at each direction of space. At low-level scattering, the method offers a complete discrimination of surface and bulk effects, whatever the micro-structural parameters. Arbitrary scattering levels can be treated in a similar way, but require the knowledge of microstructure.
Objectives: In 2015, we evaluated our practices regarding pain after breast-conserving surgery. Thereafter, we have adapted our practices by performing a systematic deep serratus plane block before the surgical incision. In 2019, we assessed the impact of these changes in terms of chronic pain. The main objective of this study was to evaluate the prevalence of chronic pain 3 months after this type of surgery.Materials and Methods: All patients treated with breast-conserving surgery as outpatients were included in this prospective study between April and July 2019. After inducing general anesthesia, 20 mL of ropivacaine 3.75 mg/mL were injected under the serratus muscle. Morphine titration was performed in the recovery room according to pain scores. A pain and quality of life questionnaire was sent 3 months after surgery. A backward logistic regression model was applied to calculate the adjusted odds ratios. Results:The final analysis involved 137 patients. Three months after surgery, 43 patients (31%) reported persistent pain related to the surgery. Maximum pain in the last 24 hours was moderate to severe in 60% of cases, 16 patients (35%) took painkillers. Morphine titration in the recovery room was required in 25 patients (18%). Younger age and the use of lidocaine to prevent after injection of propofol during general anesthesia induction appeared to be protective factors for the risk of pain at 3 months (secondary endpoints).Discussion: No persistent pain at 3 months was reported in 69% of cases. Furthermore, the use of a deep serratus anterior plane block before the surgical incision has limited the need for morphine titration in the recovery room to <1 patient in 5. These evaluations of professional practices should be encouraged.
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