Vertically Displaced Research Articles

In Vitro Investigation Using a New Biomechanical Force-Torque Analysis System: Comparison of Conventional and CAD/CAM-Fixed Orthodontic Retainers.

(1) Background: After more than a decade since their first description, Inadvertent Tooth Movements (ITMs) remain an adverse effect of orthodontic retainers without a clear etiology. To further investigate the link between ITMs and the mechanical properties of different retainers, the response upon vertical loading was compared in three retainer types (two stainless steel and one nickel-titanium). The influence of different reference teeth was also considered. (2) Methods: Three retainers (R1, R2, R3) were tested in a newly developed biomechanical analysis system (FRANS). They were bonded to 3D-printed models of the lower anterior jaw and vertically displaced up to 0.3 mm. Developing forces and moments were recorded at the center of force. (3) Results: The vertical displacement caused vertical forces (Fz) and labiolingual moments (My) to arise. These were highest in the lateral incisors (up to 2.35 ± 0.59 N and 9.27 ± 5.86 Nmm for R1; 1.69 ± 1.06 N and 7.42 ± 2.65 Nmm for R2; 3.28 ± 1.73 N and 15.91 ± 9.71 Nmm for R3) for all analyzed retainers and with the R3 retainer for all analyzed reference teeth, while the lowest Fz and My values were recorded with the R1 retainer. (4) Conclusions: Displacements of 0.2 mm and larger provided forces and moments which could be sufficient to cause unwanted torque movements, such as ITMs, in all analyzed retainers. Clinicians must be mindful of these risks and perform post-treatment checkups on patients with retainers of all materials.

Effect of Aligning Forces by Two Preadjusted Edgewise Techniques on a Buccally Positioned Maxillary Canine at Varying Vertical Displacements: A Finite Element Study.

To evaluate the effect of continuous arch and piggyback mechanics in a straight wire appliance (SWA) for the alignment of buccal and variably vertically positioned maxillary canines. A three-dimensional finite element model with near-normal occlusion and buccal and vertically displaced maxillary canines was used. Two groups were created to simulate two commonly used SWAs techniques, continuous archwire (Group 1) and piggyback models (Group 2). Each group had three subgroups with varying vertical displacement of the canine from 2 to 6 mm from the occlusal plane. The displacement and stress distribution were noted in each group. As the vertical displacement increased in Group 1, the concentration of von Mises stress increased progressively at the incisal third (0.36, 0.41 and 0.44 MPa) at 2, 4, and 6 mm, respectively, with decreased maximum occlusal movement in the vertical plane with respect to the canine. Group 2 exhibited a similar pattern but greater occlusal movement of the canine compared with Group 1. A vertical displacement of 4 mm is the optimal level at which continuous arch mechanics should be considered. For displacements beyond 4 mm, the piggyback wire technique is a suitable alternative.

Quantification of maize brace root formation after vertical stalk displacement.

Maize brace roots develop from aboveground stem nodes in both upright and vertically displaced stalks. The cues that trigger brace root development after displacement are unknown. Possibilities include disturbance of the belowground roots, gravity, moisture, physical interaction, or node anatomical changes. We show that brace root formation occurs at all growth stages, with more nodes producing brace roots when plants are displaced at later growth stages. This occurs with the underground roots intact, without moisture accumulation and without physical interaction. We propose that the formation of brace roots after vertical stalk displacement is most likely due to gravity or anatomical changes at the node.

Sacral osteotomy combined with triangular osteosynthesis in the treatment of malunion and nonunion of vertically displaced pelvic fractures

BackgroundMalunion and nonunion of vertically displaced pelvic fractures result in lower limb length discrepancies, claudication, and pain. There have been few previous reports of this type of corrective surgery for these old pelvic fractures. We present a surgical technique of sacral osteotomy combined with triangular osteosynthesis in the treatment of malunion and nonunion of vertically displaced pelvic fractures and report on its short-term clinical results.MethodsWe retrospectively reviewed nine patients (five males and four females) with malunion or nonunion of vertically displaced pelvic fractures treated with sacral osteotomy and triangular osteosynthesis from April 2015 to January 2020. The age ranged from 14 to 45 years (average, 30.7 years). The time from injury to deformity correction surgery ranged from 3 months to 5 years (average, 12.8 months). The vertical displacement of a unilateral hemipelvis was 3.0–4.5 cm (average, 3.80 cm). According to AO/OTA classification at the initial fracture, there are eight cases in type C1.3 and one case in type C3.3. Sacral osteotomy and triangular osteosynthesis were used in all nine patients. The degree of unilateral hemipelvic reduction was assessed postoperatively based on measurements from the anteroposterior (AP) X-ray. Majeed score and pain visual analog scale (VAS) were used to assess the therapeutic effect of the patients during follow-up.ResultsIn all nine patients, postoperative AP X-ray showed correction displacement of 1.7–3.9 cm (average, 3.20 cm). All the patients were followed up for 6–36 months (average, 12.7 months). At the last follow-up, the Majeed score of pelvic fracture increased from an average of 53.9 points (30–84 points) preoperatively to 87.0 points (72–94 points), and the VAS score for pain decreased from an average of 6.0 points (4–8 points) preoperatively to 1.2 points (0–3 points). None had complications like infection, implant broken, screw loosening, iatrogenic nerve, and blood vessel injury.ConclusionSacral osteotomy combined with triangular osteosynthesis for the treatment of pelvic malunion and nonunion caused by sacral fractures can correct significantly vertical displacement of a unilateral pelvis, prolong limb length, and reconstruct the stability of a pelvic ring, achieving good clinical results.

A new model for the growth of normal faults developed above pre-existing structures

AbstractConstraining the mechanisms of normal fault growth is essential for understanding extensional tectonics. Fault growth kinematics remain debated, mainly because the very earliest phase of deformation through recent syn-kinematic deposits is rarely documented. To understand how underlying structures influence surface faulting, we examined fault growth in a 10 ka magmatically resurfaced region of the Krafla fissure swarm, Iceland. We used a high-resolution (0.5 m) digital elevation model derived from airborne lidar to measure 775 fault profiles with lengths ranging from 0.015 to 2 km. For each fault, we measured the ratio of maximum vertical displacement to length (Dmax/L) and any nondisplaced portions of the fault. We observe that many shorter faults (<200 m) retain fissure-like features, with no vertical displacement for substantial parts of their displacement profiles. Typically, longer faults (>200 m) are vertically displaced along most of their surface length and have Dmax/L at the upper end of the global population for comparable lengths. We hypothesize that faults initiate at the surface as fissure-like fractures in resurfaced material as a result of flexural stresses caused by displacements on underlying faults. Faults then accrue vertical displacement following a constant-length model, and grow by dip and strike linkage or lengthening when they reach a bell-shaped displacement-length profile. This hybrid growth mechanism is repeated with deposition of each subsequent syn-kinematic layer, resulting in a remarkably wide distribution of Dmax/L. Our results capture a specific early period in the fault slip-deposition cycle in a volcanic setting that may be applicable to fault growth in sedimentary basins.

Holocene Paleoseismology of the Steamboat Mountain Site: Evidence for Full-Length Rupture of the Teton Fault, Wyoming

ABSTRACT The 72-km-long Teton fault in northwestern Wyoming is an ideal candidate for reconstructing the lateral extent of surface-rupturing earthquakes and testing models of normal-fault segmentation. To explore the history of earthquakes on the northern Teton fault, we hand-excavated two trenches at the Steamboat Mountain site, where the east-dipping Teton fault has vertically displaced west-sloping alluvial-fan surfaces. The trenches exposed glaciofluvial, alluvial-fan, and scarp-derived colluvial sediments and stratigraphic and structural evidence of two surface-rupturing earthquakes (SM1 and SM2). A Bayesian geochronologic model for the site includes three optically stimulated luminescence ages (∼12–17 ka) for the glaciofluvial units and 16 radiocarbon ages (∼1.2–8.6 ka) for the alluvial-fan and colluvial units and constrains SM1 and SM2 to 5.5±0.2 ka, 1σ (5.2–5.9 ka, 95%) and 9.7±0.9 ka, 1σ (8.5–11.5 ka, 95%), respectively. Structural, stratigraphic, and geomorphic relations yield vertical displacements for SM1 (2.0±0.6 m, 1σ) and SM2 (2.0±1.0 m, 1σ). The Steamboat Mountain paleoseismic chronology overlaps temporally with earthquakes interpreted from previous terrestrial and lacustrine paleoseismic data along the fault. Integrating these data, we infer that the youngest Teton fault rupture occurred at ∼5.3 ka, generated 1.7±1.0 m, 1σ of vertical displacement along 51–70 km of the fault, and had a moment magnitude (Mw) of ∼7.0–7.2. This rupture was apparently unimpeded by structural complexities along the Teton fault. The integrated chronology permits a previous full-length rupture at ∼10 ka and possible partial ruptures of the fault at ∼8–9 ka. To reconcile conflicting terrestrial and lacustrine paleoseismic data, we propose a hypothesis of alternating full- and partial-length ruptures of the Teton fault, including Mw∼6.5–7.2 earthquakes every ∼1.2 ky. Additional paleoseismic data for the northern and central sections of the fault would serve to test this bimodal rupture hypothesis.

Using 14C-Dated Peat Beds for Reconstructing Subsidence by Compression in the Holland Coastal Plain of the Netherlands

ABSTRACT Koster, K.; Cohen, K.M.; Stafleu, J., and Stouthamer, E., 2018. Using 14C-dated peat beds for reconstructing subsidence by compression in the Holland coastal plain of the Netherlands. Subsidence in the Holland coastal plain of the Netherlands was reconstructed from the vertical displacement of Holocene peat layers below their reference groundwater levels at the time of peat formation. This quantifies the part of subsidence that is due to compression processes and allows specification of the current state of peat compression in a map. 14C-dating of peat layers found intercalated in the Holocene sequence were used in the reconstruction. This dataset was combined with results from a recent coastal-deltaic plain wide three-dimensional (3D) interpolation of reference palaeo-groundwater levels, at which the intercalated peats are thought to have formed before they were buried, compressed, and vertically displaced. Empiric relations between reconstructed displacement and the thickness of overburden were...

Coupling cosmogenic nuclides and luminescence dating into a unified accumulation model of aeolian landforms age and dynamics: The case study of the Kalahari Erg

Abstract Sand deposits cover extensive areas both in the northern and southern hemispheres and the timing and chronology and processes that govern their dynamics are of major interest. Luminescence-based dating methods, are used to date episodic aeolian events but are restricted to late Quaternary deposits, and only reveal the last cycle of sediment burial and not the time of sand existence in the landscape. Burial ages modelled from cosmogenic nuclides reach further back in time, but are usually inferred as minimal deposition ages. It is apparent that standard dating methods, when applied individually, have limited applicability for determining both the age and the processes that form aeolian deposits. This study presents an approach that integrates luminescence dating and cosmogenic burial dating into a stochastic model developed to reproduce sand formation and migration. The model is based on a process in which quartz grains are vertically displaced through a sand column simulating dune migration across the landscape. A range of vertical displacement rates is compiled from published luminescence ages of dated dune fields of varied settings throughout the world. Using these vertical movement rates, sand is recycled up and down a depth profile coupled with a step-wise calculations of cosmogenic nuclides accumulation and decay, alongside OSL signal accumulation. When the modelled sand grains are buried, their luminescence signal grows while 26Al and 10Be decay or accumulate as a function of their respective radioactive decay and production rate, which is governed by cosmic rays attenuation. When sand is exposed at the surface, the luminescence signal is reset and cosmogenic nuclide production is maximized. Each simulation is terminated when the modelled concentrations of 26Al and 10Be reach measured concentrations in actual sand samples. Luminescence data therefore provide the time since last exposure at the surface (i.e. the last depositional cycle), whereas the cosmogenic nuclides provide a long-term estimate of sand residence in the landscape reflecting also weathering and erosion of the source bedrock. The southern Kalahari dune field at Mamatwan, South Africa, is used as a case study to test the presented approach. Model results show that optically stimulated luminescence ages which range between 1 and 10 Ka, only reflect the last cycle of sand migration, while cosmogenic nuclides minimal burial ages are greater than 1 Ma. Furthermore, the simulation results indicate two peaks at 1.5–2.2 Ma and at 4.2–5.2 Ma, suggesting two main phases of sand introduction to the Kalahari during the Pliocene and Pleistocene. Finally, the modelled ages are concurrent with regional environmental and climatic events. The model presented in this study provides a powerful tool for estimating the emergence of sand in a given landscape, and also for understanding the dynamic evolution of any dune field and the mechanisms behind dune migration.

Historical coseismic surface deformation of fluvial gravel deposits, Schafberg fault, Lower Rhine Graben, Germany

Intraplate earthquakes pose a significant seismic hazard in densely populated rift systems like the Lower Rhine Graben in Central Europe. While the locations of most faults in this region are well known, constraints on their seismogenic potential and earthquake recurrence are limited. In particular, the Holocene deformation history of active faults remains enigmatic. In an exposure excavated across the Schafberg fault in the southwestern Lower Rhine Graben, south of Untermaubach, in the epicentral region of the 1756 Duren earthquake (M L 6.2), we mapped a complex deformation zone in Holocene fluvial sediments. We document evidence for at least one paleoearthquake that resulted in vertical surface displacement of 1.2 ± 0.2 m. The most recent earthquake is constrained to have occurred after 815 AD, and we have modeled three possible earthquake scenarios constraining the timing of the latest event. Coseismic deformation is characterized by vertical offset of sedimentary contacts distributed over a 10-m-wide central damage zone. Faults were identified where they fracture and offset pebbles in the vertically displaced gravel layers and fracture orientation is consistent with the orientation of the Schafberg fault. This study provides the first constraint on the most recent surface-rupturing earthquake on the Schafberg fault. We cannot rule out that this fault acted as the source of the 1756 Duren earthquake. Our study emphasizes the importance of, and the need for, paleoseismic studies in this and other intracontinental regions, in particular on faults with subtle geomorphic expression that would not typically be recognized as being potentially seismically active. Our study documents textural features in unconsolidated sediment that formed in response to coseismic rupturing of the underlying bedrock fault. We suggest that these features, e.g., abundant oriented transgranular fractures in their context, should be added to the list of criteria used to identify a fault as potentially active. Such information would result in an increase of the number of potentially active faults that contribute to seismic hazards of intracontinental regions.

Radiological and functional outcomes 2.7 years following conservatively treated completely displaced midshaft clavicle fractures.

It is unclear whether all completely displaced midshaft clavicle fractures require primary surgical intervention. The aim of this study was to elucidate the radiological and clinical outcomes after conservative treatment, and to identify subgroups at risk of an inferior outcome. Retrospective case series. Level II trauma center. Between 2005 and 2008, 122 patients were conservatively treated for a completely displaced midshaft clavicle fracture of whom 92 were eligible for inclusion in this study. Of these, 59 completed the study after a median of 2.7 years after the fracture (min-max, 1.1-4.9). The patients received the standard treatment administered at our institution at the time: nonsurgically with a sling without physiotherapy. Patients with painful nonunions were subsequently offered surgery. At follow-up, the patients' Disabilities of Arm, Shoulder, and Hand (DASH) and the Constant scores were evaluated. Radiographs were taken at follow-up and compared to those taken acutely. Nonunion was found in 9 of the 59 (15.3%) patients. Twenty-four (24%) patients reported a fair-to-poor DASH score (i.e. >20). Patients with fractures that were vertically displaced by more than 100% (one bone width) were significantly less satisfied than those with fractures vertically displaced at 100% (p = 0.04). Initial shortening of more than 15 mm was not associated with a worse outcome or nonunion. The odds ratio of developing a nonunion increased with age (p = 0.04). By treating completely displaced midshaft clavicle fractures conservatively with a sling and offering plate fixation for eventual painful nonunions, we found a 24% risk of a fair or poor clinical result with a DASH score over 20. A vertical displacement of more than 100 % between the main fragments on the initial radiograph was associated with an inferior clinical outcome in this study. IV.

Deformation induced topographic effects in inversion of temporal gravity changes: First look at Free Air and Bouguer terms

Abstract We review here the gravitational effects on the temporal (time-lapse) gravity changes induced by the surface deformation (vertical displacements). We focus on two terms, one induced by the displacement of the benchmark (gravity station) in the ambient gravity field, and the other imposed by the attraction of the masses within the topographic deformation rind. The first term, coined often the Free Air Effect (FAE), is the product of the vertical gradient of gravity (VGG) and the vertical displacement of the benchmark. We examine the use of the vertical gradient of normal gravity, typically called the theoretical or normal Free Air Gradient (normal FAG), as a replacement for the true VGG in the FAE, as well as the contribution of the topography to the VGG. We compute a topographic correction to the normal FAG, to offer a better approximation of the VGG, and evaluate its size and shape (spatial behavior) for a volcanic study area selected as the Central Volcanic Complex (CVC) on Tenerife, where this correction reaches 77% of the normal FAG and varies rapidly with terrain. The second term, imposed by the attraction of the vertically displaced topo-masses, referred to here as the Topographic Deformation Effect (TDE) must be computed by numerical evaluation of the Newton volumetric integral. As the effect wanes off quickly with distance, a high resolution DEM is required for its evaluation. In practice this effect is often approximated by the planar or spherical Bouguer deformation effect (BDE). By a synthetic simulation at the CVC of Tenerife we show the difference between the rigorously evaluated TDE and its approximation by the planar BDE. The complete effect, coined here the Deformation Induced Topographic Effect (DITE) is the sum of FAE and TDE. Next we compare by means of synthetic simulations the DITE with two approximations of DITE typically used in practice: one amounting only to the first term in which the VGG is approximated by normal FAG, the other adopting a Bouguer corrected normal FAG (BCFAG).

Analysis of the characteristics of slot design affecting resistance to sliding during active archwire configurations

BackgroundDuring orthodontic treatment, a low resistance to slide (RS) is desirable when sliding mechanics are used. Many studies showed that several variables affect the RS at the bracket-wire interface; among these, the design of the bracket slot has not been deeply investigated yet. This study aimed to clarify the effect of different slot designs on the RS expressed by five types of low-friction brackets in vertical and horizontal active configurations of the wire.MethodsFive low-friction brackets (Damon SL II, Ormco, Orange, CA, USA; In-Ovation, GAC International, Bohemia, NY, USA; Quick, Forestadent, Pforzheim, Germany; Time 2, AO, Sheboygan, WI, USA; Synergy, RMO, Denver, CO, USA) coupled with an 0.014-in NiTi thermal wire (Therma-Lite, AO) were tested in two three-bracket experimental models simulating vertical and horizontal bracket displacements. A custom-made machine was used to measure frictional resistance with tests repeated on ten occasions for each bracket-wire combination. Design characteristics such as the mesio-distal slot width, slot depth, and presence of chamfered edges at the extremities of the slot were evaluated on SEM images (SUPRA, Carl Zeiss, Oberkochen, Germany) and analyzed in relation to the data of RS recorded.ResultsTime 2 was found to show the higher frictional forces (1.50 and 1.35 N) in both experimental models (p < 0.05), while Quick and Synergy brackets showed the lower frictional values in the vertical (0.66 N) and in the horizontal (0.68 N) bracket displacements, respectively. With vertically displaced brackets, the increased mesio-distal slot width and the presence of clear angle at mesial and distal slot edges increase the values of RS. With brackets horizontally displaced, the RS expressed by the wire is influenced simultaneously by the depth of the slot, the mesio-distal slot width, and the presence of clear angle at the extremities of the slot base, the clip, or the slide.ConclusionIn order to select the proper low-friction bracket system, clinicians should consider specific characteristics of slot design apart from the wire engaging method.

Experimental Device to Electromechanically Characterize 3-Strand $\hbox{Nb}_{3}\hbox{Sn}$ Samples Under Transverse Load

Triplet cables are the basic cable element of CICC cables, and understanding their electromechanical behaviors under transverse loads is of critical importance to evaluate the electromagnetic behaviors of large cables. This paper describes a new compact experimental device to characterize electromechanically single strand and triplet cable samples as well as HTS tapes under transverse loads. The device has been built and tested with significant reduction of the cost of the experiment compared to a previously used hairpin sample device. Critical current measurements as a function of transverse mechanical load at 12 T were successfully performed on triplets using ITER Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn wire. The transversely loaded section of the samples is 110 mm in length, longer than the typical twist pitch lengths of first-stage triplets of CICC. The load is applied by using a gear system driven by a 1/2 HP motor. A wedge, vertically displaced by the motor, moves other pressing components transversely. Those parts ultimately apply transverse compression on the cable. A load cell and an extensometer are used to measure the absolute vertical load and displacement, respectively. Limitations and challenges of this compact transverse load device design are discussed together with some experimental results.

Thin layers of Pseudo‐nitzschia spp. and the fate of Dinophysis acuminata during an upwelling‐downwelling cycle in a Galician RÃa

Fine‐resolution measurements of phytoplankton and physical parameters were made from 31 May to 14 June 2005 in the Ría de Pontevedra (Spain), which is subject to seasonal upwelling. The main objective of this work was to elucidate physical‐biological interactions leading to subsurface aggregations of toxin‐producing microalgae (Pseudo‐nitzschia spp. and Dinophysis spp.). A sequence of upwelling‐relaxation‐upwelling‐downwelling events was recorded with a moored Acoustic Doppler Current Profiler (ADCP). Thin layers (TLs) of Pseudo‐nitzschia spp. and other diatoms (up to 30 µg chlorophyll a L−1) developed and persisted in the pycnocline above cooler (12.5ºC) upwelled water but were vertically displaced and even dispersed during downwelling. The establishment of steep pycnoclines after upwelling pulses and the formation of TLs of Pseudo‐nitzschia spp. and other diatoms suggest that pycnoclines may act as retention areas for these populations. Their vertical displacement during downwelling would explain different patterns observed in the contamination of benthic resources and raft‐mussels. A decimeter‐scale segregation of Pseudo‐nitzschia micans and Dinophysis acuminata populations was observed. The population of D. acuminata, present since March 2005 in Ría de Pontevedra, was never found within the pycnocline, did not perform any significant vertical migration, and was not dispersed during upwelling. Instead, it formed patches (up to 8 × 103 cell L−1) in the warmer (15‐18ºC) surface (0‐4 m) waters associated with a diurnal thermocline, and it spread throughout the ría into a near‐surface layer during relaxation and downwelling. These results demonstrate the importance of considering species‐specific behavior to predict the location of cell maxima.

The contrast of inclusions compared with that of micropipes in back-reflection synchrotron white-beam topographs of SiC

Images of inclusions in synchrotron white-beam back-reflection X-ray topographs appear as spots of light contrast surrounded by darker rings, resembling images of micropipes, which appear as distinct white circles surrounded by dark rings. Section topographs taken across the centers of micropipes gave vertically displaced two-tailed images, arising from the helical tilt of the reflecting planes about the micropipes' screw dislocation axes. Section topographs taken across the inclusions showed no vertical displacement, only dark bars bracketing a region of depleted contrast, arising from the convex bulge of the reflecting planes lying above the inclusion. The features of the inclusion images could be reproduced in computer simulations based on the elastic displacement function of a spherical inclusion in a semi-infinite solid, and compared with others based on the displacement function of a screw dislocation in an infinite solid.

Acute aortic dissection during vertical displacement of the heart in off-pump coronary artery bypass grafting (OPCAB)

respectively, by which we judged that the patient would tolerate the operation. A coronary angiogram revealed stenoses in segments 1, 2, 5, and 13. An OPCAB was planned to include grafting the left internal thoracic artery (LITA) to segment 8, the right internal thoracic artery (RITA) to segment 2, and the radial artery (RA) to segment 14. After induction of general anesthesia with tracheal intubation, we established vital monitoring, including direct arterial pressure (with a catheter placed in the right RA), pulmonary arterial pressure, central venous pressure, and continuous cardiac output (with a pulmonary artery catheter through the right internal jugular vein). After median sternotomy, designated grafts were obtained from the LITA, the RITA, and the left RA. Because significant decreases in cardiac output and blood pressure were expected during the procedure, due to the age of the patient, we employed percutaneous/partial cardiopulmonary support (PCPS). The PCPS was operated with cannulations into the right femoral artery and the right atrium. During grafting of the RA graft to segment 14, when the heart was vertically displaced with a Star-fish stabilizer (Medtronic, Minneapolis, MN, USA) (Fig. 1), the monitored pressure waveform from the right RA abruptly disappeared. Simultaneously, an operator noticed a change in the color of the surface of the ascending aorta. The operator examined the aorta by direct ultrasonography, which revealed acute dissection of the ascending aorta. The surgeons decided to perform a graft replacement of the ascending aorta, and started to establish CPB with an arterial cannula placed into the right femoral artery, as well as venous cannulae placed into the superior and inferior cavenous veins through the right atrium. During the preparation for CPB, we intravenously administered thiamylal (5mg·kg 1), a continuous infusion of which was started simultaneously at a rate of 4mg·kg 1·h 1, and we began to chill the patient’s head with ice bags so as to protect his brain from hypoxic

Paleoseismicity of the northern Horohoro Fault, Taupo Volcanic Zone, New Zealand

Trench excavations have provided constraints on the recent paleoseismic history of the northern Horohoro Fault, one of the faults of the Taupo Fault Belt (TFB), a belt of northeast‐striking normal faults that run along the axis of the Taupo Volcanic Zone (TVZ). We excavated two trenches across the northernmost part of the fault where it displaces two Quaternary terraces of different ages. The trench exposures reveal a series of alluvial and volcanic fall deposits, ranging in age from c. 25 to 1.75 ka, that are vertically displaced across the steeply southeast‐dipping fault. The trench data confirm that the fault is active and indicate that it has ruptured at least three times within the last c. 26 000 yr and twice within the last c. 15 700 yr, with an average vertical component of displacement of c. 1.1 m per rupture. The most recent surface rupture occurred between 1750 and 8050 yr ago. Because the fault has ruptured within the last 20 000 yr, we consider it to be part of the modern TFB, the region that accommodates most of the modern extension in the TVZ. The post‐c. 25 ka vertical displacement rate on the northern Horohoro Fault, which runs along the northwest boundary of the TFB, is 0.14–0.2 mm/yr at the trench site, lower than that of many of the faults within the modern TFB. It is unclear if the whole Horohoro Fault or just the northern section is active. If the latter, then the fault may only be accommodating strain associated with a bend or step in the TFB near Rotorua.

Vertical displacement rates on Quaternary faults, Wanganui Basin

Abstract Wave-cut platforms of late Quaternary marine terraces between Hawera and Marton in Wanganui Basin are vertically displaced by several faults. The faults are probably high-angle normal, and strike generally northeast. Of the four faults that are known to displace surfaces of different age, two show increasing displacements with increasing age, and two show no change with age. Fault traces typically consist of discontinuous, subparallel scarps, up to 1.5 km long and up to several metres high. Some scarps display a left stepping, en echelon pattern, consistent with a component of dextral horizontal movement, though horizontal displacement of terrace risers isnotevident. Average rates of vertical movement on the faults vary between 0.02 and 0.2 mm/yr, much less than rates of vertical and horizontal movement documented for many other faults in New Zealand. One fault, the Nukumaru Fault, shows a constant rate of vertical movement averaging 0.07 mm/yr for the last 2.2 million years. The faults are tentatively interpreted as bending-moment faults, associated with folding.

Late Quaternary Vertical Displacement Rate Across the Fish Springs Fault, Owens Valley Fault Zone, California

AbstractA cinder cone located 11 km south of Big Pine, California, is vertically displaced 78 ± 6 m by the Fish Springs fault of the Owens Valley fault zone. The surfaces of Tahoe-age and Tioga-age alluvial fans that overlie the cone are vertically displaced 31 ± 3 and 3.3 ± 0.3 m, respectively. Neither the cinder cone nor the Tioga-age fan appears to have been laterally offset. The cone is dated by the39Ar/40Ar method at 314,000 ± 36,000 yr B.P. (2σ), indicating an average late Quaternary vertical displacement rate of 0.25 ± 0.03 mm/yr (2σ). The age of the Tahoe glaciation is uncertain, but probably corresponds to the age of marine oxygen isotope stage 4 and/or 6 (65,000–75,000 and 128,000–195,000 yr, respectively). If the older fan were deposited during stage 4, then the average post-Tahoe vertical displacement rate probably was at least twice the pre-Tahoe late Quaternary rate. If the displacement rate has been constant during the last 314,000 yr, then the surface of the Tahoe-age fan is dated at 124,000 ± 19,000 yr B.P., and the bulk of the fan most likely would have been deposited during stage 6. Based on the displacement of the surface of the Tioga-age (10,600 – 26,000 yr) fan, the average Holocene displacement rate appears to have been slightly less than the average late Quaternary rate.

Tidally generated high-frequency internal wave packets and their effects on plankton in Massachusetts Bay

Tidally generated internal wave packets occur twice a day during late summer in Massachusetts Bay, U.S.A. The packets are formed at Stellwagen Bank and propagate into the Bay at about 60 cm sec-; they dissipate in shallow water at the western side of the Bay. The dominant waves in packets have lengths of about 300 m, periods of between 8 and 10 min, and amplitudes of up to 30 m. Overturning of the waves has been observed acoustically over Stellwagen Bank, in the deep (80 m) waters in the center of the Bay, and during dissipation in shallow water. The effects of the internal waves on the distribution of plankton were investigated in August 1977 using an instrument package (Longhurst-Hardy Plankton Recorder, in situ fluorometer, CTD) towed either at a constant depth or following an isotherm through wave packets. Phytoplankton and zooplankton appear to be carried passively up and down by the internal waves; the data were insufficient to resolve any active response by zooplankton to vertical displacements by the waves. Vertical distributions of the plankton were altered by overturning of waves and subsequent mixing. Patterns of horizontal distributions of plankton determined by constant-depth tows were dominated by the effects of internal wave vertical displacements. Isotherm-following tows removed much of the variability due to wave displacement, but problems of following rapidly moving isotherms introduced considerable smallerscale variability. Changes in zooplankton abundance on tow length scales (600-1200 m) were not correlated with temperature, salinity, or density; some significant correlations with chlorophyll fluorescence occurred when internal wave activity was present. Twice a day for several hours or more, phytoplankton were vertically displaced by as much as 30 m, with a period of about 10 min. The light level plant cells experienced varied from 0.1 to 26% of the ambient surface illumination. This rapid change in light should alter fluorescence yields of plant cells and affect continuous in situ measurements of chlorophyll fluorescence. The timing of internal wave packets varies with the semidiurnal tidal cycle and therefore interacts with the day-night cycle to significantly alter the light regime experienced by plant cells over a two-week period. This could affect the primary productivity of the Bay in the area affected by internal wave packets. The sporadic occurrence of internal wave overturning and mixing events in the deep waters of the Bay could enhance primary production by increasing nutrient input to the mixed layer. This effect should be greatly enhanced in the shallow waters where the internal waves 1. Scripps Institution of Oceanography, La Jolla, California, 92093, U.S.A. 2. Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, 02543, U.S.A. 3. Gulf Research and Development Company, P.O. Box 2038, Pittsburgh, Pennsylvania, 15230, U.S.A.