Black Americans face significant challenges related to sleep health, including insufficient sleep duration (IS), defined as fewer than 7 h per night, and compromised sleep quality, understood as the ...subjective perception of one's sleep experience. These issues not only carry broad health implications but also exacerbate existing health disparities.
This study utilizes the Socio-Ecological Model (SEM) and Life-Course Approach (LCA) to comprehensively examine the multilevel influences on sleep health among Black Americans. The SEM explores how factors from individual biological nuances to overarching public policies impact sleep, while the LCA focuses on the temporal impact of early life experiences, developmental transitions, and the accumulation of advantages and disadvantages.
Our literature review reveals a complex interaction of societal structures, environmental factors, and individual behaviors that influence both the duration and quality of sleep among Black Americans. The nuanced understanding provided by combining the SEM and LCA frameworks highlights critical areas for intervention.
The study identifies potential pathways for public health interventions and strategies that take a holistic and multi-faceted approach. These interventions aim to address both the quantitative aspects of sleep, such as duration, and qualitative aspects, such as sleep quality, to improve sleep health among Black Americans comprehensively.
Effectively addressing the intertwined issues of sleep duration and quality is crucial for enhancing overall sleep health in Black American communities. Our findings underscore the importance of integrated approaches that consider both socio-ecological and life-course factors in tackling sleep health disparities.
Nanometric displacement measurements by Extrinsic Fiber Fabry-Perot interferometers (EFPI) is extremely susceptible to external environmental changes. Temperature, in particular, has a remarkable ...influence on the optical power and wavelength of the laser diode in use, in addition to the thermal expansion of the mechanical structure. In this paper we propose an optimization of the EFPI sensor in order to use it for very long-term (more than one year) and for high-precision displacement measurements. For this purpose, a real time and adaptive estimation procedure based on a homodyne technique and a Kalman filter is established. During a sinusoidal laser diode current modulation, the Kalman filter provides a correction of the amplitude drift caused by the resultant optical power modulation and external perturbations. Besides, stationary temperature transfer operators are estimated via experimental measurements to reduce the additive thermal noise induced in the optical phase and mechanical components.
Based on the agreement between geodetic and geological plate velocities, interplate fault slip rates are usually considered constant over long periods of time. However, measurements made at different ...time scales on intracontinental faults suggest that slip rate evolves with time. We examine the slip evolution of a fault embedded in an elastic lithosphere loaded by plate motion. We first assume that the fault friction varies due to a climatic cause. Then we show that high fault stress and low lithospheric stiffness favour large variations of slip rate. In the case where fault weakening is controlled by slip rate, we find that high loading velocity leads to a low stress, constant slip rate, while low loading velocity drives the fault slip rate to cycle between high and low values. This suggests that paleoseismic slip rate could overpass the loading velocity but also fall to zero for some period of time.
The effect of long term coupling in subduction zones on forearc topography is studied using a 2‐dimensional finite element model. A curved fault, representing the interface between subducting slab ...and overriding plate, has been incorporated into a model with an elastic crustal layer, a viscoelastic upper mantle, an initial topography and an effective coefficient of friction on the fault. We assume that traction arising from friction is one of the stresses acting on topography. For various friction coefficients, the change of topography after some equilibration time is computed with specific geometry and kinematic boundary conditions for three subduction zones: northern Chile, northern Japan and Tonga. While the intrinsic coefficient of friction for small rock samples is high (µ ∼ 0.6–0.8), the observed topography of forearc regions are inconsistent with an effective friction coefficient larger than 0.2.
The availability of GPS survey data spanning 22 years, along with several independent velocity solutions including up to 16 years of permanent GPS data, presents a unique opportunity to search for ...persistent (and thus reliable) deformation patterns in the Western Alps, which in turn allow a reinterpretation of the active tectonics of this region. While GPS velocities are still too uncertain to be interpreted on an individual basis, the analysis of range‐perpendicular GPS velocity profiles clearly highlights zones of extension in the center of the belt (15.3 to 3.1 nanostrain/year from north to south), with shortening in the forelands. The contrasting geodetic deformation pattern is coherent with earthquake focal mechanisms and related strain/stress patterns over the entire Western Alps. The GPS results finally provide a reliable and robust quantification of the regional strain rates. The observed vertical motions of 2.0 to 0.5 mm/year of uplift from north to south in the core of the Western Alps is interpreted to result from buoyancy forces related to postglacial rebound, erosional unloading, and/or viscosity anomalies in the crustal and lithospheric root. Spatial decorrelation between vertical and horizontal (seismicity related) deformation calls for a combination of processes to explain the complex present‐day dynamics of the Western Alps.
Key Points
Twenty‐two years of survey and 16 years of permanent GPS data analyzed in several independent solutions highlight persistent deformation patterns in the Western Alps
GPS data show extension in the center of the belt and compression along the eastern and western forelands, coherent with earthquake focal mechanisms
Spatial decorrelation between uplift and co‐located extension and seismicity calls for a complex process driving the present‐day dynamics of the Western Alps
The Western Alps are among the best studied collisional belts with both detailed structural mapping and also crustal geophysical investigations such as the ECORS and EGT seismic profile. By contrast, ...the present-day kinematics of the belt is still largely unknown due to small relative motions and the insufficient accuracy of the triangulation data. As a consequence, several tectonic problems still remain to be solved, such as the amount of N-S convergence in the Occidental Alps, the repartition of the deformation between the Alpine tectonic units, and the relation between deformation and rotation across the Alpine arc. In order to address these problems, the GPS ALPES group, made up of French, Swiss and Italian research organizations, has achieved the first large-scale GPS surveys of the Western Alps. More than 60 sites were surveyed in 1993 and 1998 with a minimum observation of 3 days at each site. GPS data processing has been done by three independent teams using different software. The different solutions have horizontal repeatabilities (N-E) of 4-7 mm in 1993 and 2-3 mm in 1998 and compare at the 3-5-mm level in position and 2-mm/ yr level in velocity. A comparison of 1993 and 1998 coordinates shows that residual velocities of the GPS marks are generally smaller than 2 mm/yr, precluding a detailed tectonic interpretation of the differential motions. However, these data seem to suggest that the N-S compression of the Western Alps is quite mild (less than 2 mm/yr) compared to the global convergence between the African and Eurasian plate (6 mm/yr). This implies that the shortening must be accomodated elsewhere by the deformation of the Maghrebids and/ or by rotations of Mediterranean microplates. Also, E-W velocity components analysis supports the idea that E-W extension exists, as already suggested by recent structural and seismotectonic data interpretation.
We model the recent deformation along a lithospheric‐scale cross section perpendicular to the northern part of the Baikal rift zone (BRZ) with two‐dimensional finite element models. Using realistic ...lithospheric structure and rheological properties and imposing extension as a far‐field boundary condition, we find a model that matches reasonably well the topography, observed deformation pattern, gravity anomalies, and age of formation of the northern BRZ. Our results suggest that (1) extensional strain can occur away from the main rift basin in the Sayan Baikal range and create, depending on the rheological properties of the lithosphere, a large “off‐rift” basin analogous to the Barguzin basin, or a series of basins and ranges, as observed in the southern part of the Sayan Baikal range, (2) anelasticity plays a major role by participating in the uplift of rift shoulders and hanging wall deformation, and allowing the subsidence and tilting of the hanging wall along high‐angle planar normal faults, (3) the lower crust accommodates differential strain between the brittle upper crust and upper mantle by horizontal shear and lateral flow towards the regions of crustal and mantle thinning, (4) far‐field extensional stress and a lithospheric discontinuity inherited from Paleozoic tectonic events are sufficient to initiate rifting and basin subsidence, and (5) there is no, or very little, dynamic contribution of a hypothetic asthenospheric plume under the BRZ, at least in the recent phase of its evolution (“fast rifting stage”, 3.5 Myr).
The seismic activity of the Ligurian Basin, the northeastern termination of the western Mediterranean basin, is larger than in surrounding regions, even though recent geodetic studies attest that ...this area is subject to very low levels of deformation. This basin is an example of a type of passive margins that cannot be considered solely as inert sites of sedimentation and of progressive subsidence and that are reactivated in a compressive pattern; other examples include the Kwanza basin (Angola) and the Brazil margin. We investigated, by means of 2‐D thermomechanical modeling, the structural and rheological heterogeneities that can lead to concentration of strain in this marginal basin. We deduced that the deformation of the basin is due to its particular geometric features, narrow and with a thick surrounding continental crust, related to its position at the southern termination of the Alps. This sharp transition, in terms of both geometry and rheological contrast, is a main factor in explaining the weakness of the margin. We discuss the importance of buoyancy forces versus tectonic forces, as well as thermal effects, on the observed reactivation. Influence of contrast in rheology between an oceanic‐type crust and continental crust is also studied. Geodynamical implications are proposed for the region. The good agreement between the predicted localized deformation and the observed seismicity distribution should help improve seismic hazard assessment in the region.
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