In-situ regolith seismic velocity measurement at the InSight landing site on Mars

InSight's seismometer package SEIS was placed on the surface of Mars at about 1.2 m distance from the thermal properties instrument HP3 that includes a self-hammering probe. Recording the hammering noise with SEIS provided a unique opportunity to estimate the seismic wave velocities of the shallow regolith at the landing site. However, the value of studying the seismic signals of the hammering was only realised after critical hardware decisions were already taken. Furthermore, the design and nominal operation of both SEIS and HP3 are non-ideal for such high-resolution seismic measurements. Therefore, a series of adaptations had to be implemented to operate the self-hammering probe as a controlled seismic source and SEIS as a high-frequency seismic receiver including the design of a high-precision timing and an innovative high-frequency sampling workflow. By interpreting the first-arriving seismic waves as a P-wave and identifying first-arriving S-waves by polarisation analysis, we determined effective P- and S-wave velocities of vP = 114+43-20 m/s and vS = 60+11-7 m/s, respectively, from around 2,000 hammer stroke recordings. These velocities likely represent bulk estimates for the uppermost several 10's of cm of regolith. An analysis of the P-wave incidence angles provided an independent vP/vS ratio estimate of 1.84+0.89-0.35 that compares well with the traveltime based estimate of 1.92+0.52-0.28. The low seismic velocities are consistent with those observed for low-density unconsolidated sands and are in agreement with estimates obtained by other methods

Quelle vie après le Locked-In syndrome?

The Locked-In Syndrome (LIS) is classically caused by an anterior pontine vascular lesion and characterized by quadriplegia and anarthria with preserved consciousness and intellectual functioning. We here review the definition, etiologies, diagnosis and prognosis of LIS patients and briefly discuss the few studies on their quality of life and the challenging end-of-life decisions that can be encountered. Some clinicians may consider that LIS is worse than being in a vegetative or in a minimally conscious state. However, preliminary data from chronic LIS survivors show a surprisingly preserved self-scored quality of life and requests of treatment withdrawal or euthanasia, though not absent, are infrequent.English AbstractJournal ArticleResearch Support, Non-U.S. Gov'tReviewinfo:eu-repo/semantics/publishe

Life with Locked-In syndrome

peer reviewedThe Locked-In Syndrome (LIS) is classically caused by an anterior pontine vascular lesion and characterized by quadriplegia and anarthria with preserved consciousness and intellectual functioning. We here review the definition, etiologies, diagnosis and prognosis of LIS patients and briefly discuss the few studies on their quality of life and the challenging end-of-life decisions that can be encountered. Some clinicians may consider that LIS is worse than being in a vegetative or in a minimally conscious state. However, preliminary data from chronic LIS survivors show a surprisingly preserved self-scored quality of life and requests of treatment withdrawal or euthanasia, though not absent, are infrequent