The Mw7.1 September 19th Puebla-Morelos (Mexico) earthquake triggered by brucite and antigorite dewatering

<p>Subduction controls key geological processes at convergent margins including seismicity and resultant seismic hazard. The September 19th 2017 Mw7.1 Mexican earthquake nucleated ~250 km from the trench within the Cocos plate near its Moho, ~57 km below Earth’s surface. The prevailing hypothesis suggests that this earthquake resulted from bending stresses occurring at the flat-to-steep subduction transition. Here, we present an alternative, but not mutually exclusive, hypothesis: the dehydration reaction brucite + antigorite = olivine + H2O in the slab mantle controls intermediate-depth seismicity along the flat portion of the subducted Cocos plate. This reaction releases a substantial amount of H2O, resulting in a large positive volume change, and thus in an increase in pore fluid pressure at the appropriate depth–temperature conditions to cause the Puebla-Morelos and other intraslab earthquakes in Mexico. The amount of H2O released by this reaction depends on the degree of serpentinization of the oceanic mantle prior to subduction. Only oceanic mantle with > 60% serpentinization—as expected along abundant deep extensional faults at the mid-ocean-ridge or where the plate bends at the outer rise—will stabilize brucite, and thus, will experience this reaction at the same depths where the September 19th 2017 earthquake nucleated.</p>

Investigation 0f Beef Brisket Palatability from Three USDA Quality Grades

ObjectivesBarbecuing and smoked meat continues to grow in popularity for food service and consumers at home. However, little research has examined the eating quality differences of point (pectoralis superficialis) and flat (pectoralis profundi) muscles across USDA quality grade. The objective of this study was to investigate differences in smoked beef brisket palatability from three USDA quality grades.Materials and MethodsBeef briskets from the USDA Prime, Average Choice, and Select quality grades (n = 54; 18 per treatment) were collected at a commercial abattoir in Omaha, NE. Briskets were trimmed to 6 mm of external fat, seasoned with a blend of 1:1 coarse kosher salt/coarse black pepper by hand (0.05% of the brisket raw weight), and were held at 2–4° for 12 h prior to cooking. Briskets were cooked in an electric pellet smoker utilizing Gold Blend Hardwood Pellets (red oak, hickory, and maple wood) for ∼4 h to an internal temperature of 63°C; wrapped in aluminum foil, placed back in the smoker for ∼4 h, and cooked to 93°C, then held in an insulated cooler until slicing. Approximately 90 min prior to serving, briskets were separated in point and flat portions, and then sliced (6 mm × 50 mm x cooked depth) perpendicular to the muscle fiber for consumer evaluation and held in warmers at (∼50°C) until serving. Each consumer (n = 360) received six test samples representing all quality grade × muscle combinations to evaluate tenderness, juiciness, flavor liking, overall liking, as well as the acceptability of these traits. Additionally, willingness to pay (WTP) was collected on an individual sample basis.ResultsAn interaction between quality grade and muscle was observed (P ≤ 0.03) for all palatability traits, proportion of acceptable samples, and WTP. Consumers could not distinguish between quality grades of the point portions for tenderness, juiciness, flavor and overall liking (P > 0.05). Point samples, regardless of quality grade were scored greater than Prime flat samples, which were intermediate (P < 0.05). Consumers similarly (P > 0.05) scored Choice and Select flat samples lower for all palatability traits compared to all other treatment combinations. In alignment with palatability traits, consumers were willing to pay the most for point portions, regardless of quality grade (P < 0.05). Consumers WTP of the Prime flat portion was intermediate, and consumers were willing to pay the least for Choice and Select flat portions (P < 0.05).Consumer acceptability followed similar trends as palatability scores. However, a greater proportion of consumers classified Choice and Select point samples as acceptable than that of Prime point samples in all categories of acceptability (P < 0.05). Consumers struggled to distinguish differences in acceptability for Choice and Select flat portions (P > 0.05) in all factors except juiciness acceptability.ConclusionQuality grade had no effect on the eating quality of the point portions of smoked briskets, and point portions received superior palatability scores to flat portions. Briskets from the Prime flat portions had greater eating quality than Choice and Select briskets from the flat portion, and consumers were willing to pay more for what they perceived as superior eating quality. This data suggests that unless consumers prefer the flat portion of the brisket there is no benefit to paying the premium for a prime brisket from a palatability standpoint.

Compound Heat Transfer Enhancement of Wavy Fin-and-Tube Heat Exchangers through Boundary Layer Restarting and Swirled Flow

This study performs a 3D turbulent flow numerical simulation to improve heat transfer characteristics of wavy finandtube heat exchangers. A compound design encompassing louver, flat, and vortex generator onto wavy fins can significantly enhance the heat transfer performance of wavy fin-and-tube heat exchangers. Replacement of wavy fins around tubes with flat fins is not effective as far as the reduction of thermal resistance is concerned, although an appreciable pressure drop reduction can be achieved. Adding two louvers with a width of 8 mm to the flat portion can reduce thermal resistance up to 6% in comparison with the reference wavy fin. Increasing the louver number and width can further decrease the thermal resistance. Also, it is found that the optimum louver angle is equal to the wavy angle for offering the lowest thermal resistance. Therefore, compound geometry with three louvers, a width of 12 mm, and the louver angle being equal to wavy angle with waffle height to be the same as fin pitch of the reference wavy fin has the most reduction in thermal resistance of 16% for a pumping power of 0.001 W. Adding punching longitudinal vortex generators on this compound geometry can further decrease thermal resistance up to 18%.

Stroke Volume Recruitability during the Third Trimester of Pregnancy

Objective It is unknown whether the heart operates in the ascending or flat portion of the Starling curve during normal pregnancy. Pregnant women do not respond to the passive leg-raising maneuver secondary to mechanical obstruction of the inferior vena cava by the gravid uterus. Our objective was to evaluate if administration of a fluid bolus increases baseline stroke volume (SV) among healthy pregnant patients during the third trimester. Study Design Healthy pregnant women who underwent elective term cesarean sections were included. A noninvasive cardiac output monitor was used to measure hemodynamic variables at baseline and after administration of a 500-mL crystalloid bolus. Results Forty-five women were included in the study. Fluid administration was associated with a statistically significant increase in SV from a baseline value of 71 ± 11 to 90 ± 19 mL (95% confidence interval [CI]: 13.67–21.49; p < 0.01) and a significant decrease in maternal heart rate from a baseline of 87 ± 9 beats per minute to 83 ± 8 after the fluid bolus (95% CI: −6.81 to −2.78; p = 0.03). No changes in peripheral vascular resistances or any other measured hemodynamic parameters were noted with volume expansion. Conclusion In healthy term pregnancy, the heart operates in the ascending portion of the Starling's curve, rendering it fluid responsive.

Permissible Parameter Ranges of Access Hole Geometries for WUF-W Connections

The welded unreinforced flange-welded web (WUF-W) connection is one of seven prequalified connections for special moment frames (SMF) specified in AISC 358-10 (2010). Previous studies reported that the cyclic behavior of WUF-W connections was strongly affected by weld access hole geometry, and some WUF-W connections did not satisfy the requirements for SMF connections. For investigating in detail the effect of access hole configurations on the cyclic behavior of WUF-W connections, this study conducts three-dimensional nonlinear finite element analyses. This study shows that the seismic behavior of WUF-W connections are strongly affected by two configuration parameters, access hole slope and length of flat portion. To satisfy the requirement for SMF connections, this study proposes a range of the access hole slope and length of flat portion for WUF-W connections considering different span-to-depth ratios, beam depths, and material types.

Bilateral Serous Retinal Detachment Associated with Inferior Posterior Staphyloma Treated with Scleral Shortening and Vitrectomy

Purpose: We report a case of bilateral serous retinal detachment (SRD) associated with inferior posterior staphyloma (IPS) treated successfully with scleral shortening. Patient and Methods: A 63-year-old woman presented with bilateral visual loss due to an SRD with IPS. The best-corrected visual acuity levels were 0.6 (20/30) and 0.5 (20/40) in the right and left eye, respectively. The patient underwent vitrectomy and scleral shortening in the right eye. The lamellar scleral crescent was resected 4 mm in width from the 5- to 8-o'clock positions. Seven interrupted 5-0 polyester sutures were placed at the edge of the lamellar scleral crescent. After 25-gauge three-port vitrectomy, the sutures were tightened. Optical coherence tomography showed decreased curvature at the staphyloma border. The choroidal thickness decreased in the superior flat portion of the fundus and increased slightly in the staphyloma. The SRD resolved 3 months postoperatively. The best-corrected visual acuity in the right eye improved to 0.8 (20/25) 6 months postoperatively. Angiography 6 months postoperatively showed decreased diffuse dye leakage at the fovea in the right eye; indocyanine green angiography did not show marked changes. Discussion: Scleral shortening with vitrectomy changes the eye wall shape, may improve the retinal pigment epithelial integrity, and may be a treatment option for SRD with IPS.

Deformation Characteristic of Thin Stainless Gasket Material

Previous studies on corrugated metal gaskets have established that the contact width, contact stress, and surface roughness are important design parameters for optimizing gasket performance. However, the metal gaskets studied previously required a high axial force for the tightening process; in addition that metal gaskets tend to corrode easily. In this study, we examined the deformation mode of a thin stainless gasket using a finite element method (FEM) analysis. A final evaluation was made using a compression examination. The analysis based on the dimension of flat and convex portion. The load, deformation mode, and contact stress were obtained through a simulation. Based on the deformation of the flat and convex portions, the deformation modes were divided into three types. The deformation mode of the thin stainless gasket material has a higher probability of deformation in mode I when the aspect ratio of the length of the flat portion to the length of the convex portion, L/D, increases.

Shape Characterization of a Simply Supported Beam in Morphing

Rather than address morphing in the conventional way of applying forces to a fixed-compliance structure, this work addresses morphing in a structure that can exhibit variable compliance. Specifically, this work addresses the shape morphing of a simply-supported elastic beam from a forward approach perspective, that is, determining beam shape due to applied forces. The focus on this study is on the spatial distribution of the structure due to local/total modulus change in its steady state condition. The resulting morphed shapes are quantified in terms of the characteristic parameters, such as spatial distribution of the peaks of the shapes, deviation from the axis of the symmetry and, in case of flat-top shapes, the width of the flat portion.